历史笔记 3

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历史笔记 3

原载于 https://github.com/district10/blog/blob/master/_pages/notes.md。

舌尖上的忘词&背单词的秘诀 @

TOT State (tip of the tongue)

一外国朋友见到蝌蚪惊呼 look, nigga sperms!
忘记老鼠怎么说，只好说是 Tom and Jerry 的 Jerry。
给留学生指路，指着面包车说 “a car like bread”，对方小哥机智的 get 到 “A van car?”
把拉肚子说成 shit like soup…
想不起来脚趾怎么说，说成了 foot finger，结果对方笑趴下了
一个哥们在国外旅游时忘了吸管的英文叫啥，结果说成了sucker…

refs and see also

舌尖上的忘词&背单词的秘诀

dpkg @

sudo dpkg -i DEB_PACKAGE # install
sudo dpkg -r DEB_PACKAGE # remove

DPKG commands

There are two actions, they are dpkg-query and dpkg-deb.
Install a package

# sudo dpkg -i {package_name}
# sudo dpkg -i skype-ubuntu-precise_4.2.0.11-1_i386.deb

Remove a package

# sudo dpkg -r {package_name}
# sudo dpkg -r vlc

Remove a package and its configuration files

# sudo dpkg -P {package_name}
# sudo dpkg -P vlc

List all installed packages.

You can pipe the command to less (a pager) so you can more easily scroll the content:

# dpkg -l | less

Check if the package is installed or not

# dpkg -l {package_name}
# dpkg -l vlc

Check if the package is installed or not, and if it is, launch it:

# dpkg -l | vlc

See whether a package is installed or not

And this will show the location where the package will be installed. Here -S (capital S) to search whether the package was installed or not.

# sudo dpkg -S {package_name}
# sudo dpkg -S skype

Install a *.deb package from a specified location

Here -R is recursive. (Recursively handle all regular files matching the pattern *.deb found at specified directories and all of its subdirectories).

# sudo dpkg -R --install {package_location}
# sudo dpkg -R --install /home/sysadmin/soft

Show package details

Here -p (lowercase p) will show the package info:

# dpkg -p {package_name}
# dpkg -p apache2

View the content of a package

Use -c (lowercase c) to show the content:

# sudo dpkg -c {package_name}
# sudo dpkg -c skype-ubuntu-precise_4.2.0.11-1_i386.deb

Extract the *.deb package file

Use -x (lowercase x) to extract:

# dpkg -x {package_name} {location_were_to_extract}
# dpkg -x libqt4-phonon_4.6.3-4+squeeze1_i386.deb /home/sysadmin/

Extract and display the filenames contained in a package

Use -X (uppercase X) to display the content with extraction.

# dpkg -X {package_name} {location_were_to_extract}
# dpkg -X libqt4-phonon_4.6.3-4+squeeze1_i386.deb /home/sysadmin/

Display information about a package

Here -I stands for information:

# dpkg -I {package_name}
# dpkg -I libqt4-phonon_4.6.3-4+squeeze1_i386.deb

Reconfigure an already installed package

dpkg-reconfigure reconfigures packages after they already have been installed. Pass it the name(s) of a package or packages to reconfigure. It will ask configuration questions, much like when the package was first installed.

# dpkg-reconfigure postfix

This will reconfigure postfix the same way as when you installed it for the first time.

Need to know more about dpkg commands? Have a look at the manual page:

# man dpkg

If you use an RPM-based distro, you may be able to install this deb using alien, or try

ar p $DEB data.tar.gz | sudo tar xvz --strip-components 2 -C /usr/local

where $DEB is the path to the downloaded deb.

travis @

sed -i "s/AccessKey/$QAK/g" qiniu_sync
sed -i "s/SecretKey/$QSK/g" qiniu_sync

持续集成（ Continuous Integration）或者CI，是一个已经在软件开发中已经流行好一阵子的东西了，但是最近逐渐在运维界中获得了越来越多的拥趸。CI提出来是为了解决多个开发者在同一个代码库开发的时候造成的集成问题。基本上，两个开发者在同一样的代码上进行开发就会产生冲突，并且只有在之后很久才会发现这些冲突。

The complete build lifecycle, including three optional deployment steps and after checking out the git repository and changing to the repository directory, is:

before_install
install
before_script
script
after_success or after_failure
OPTIONAL before_deploy
OPTIONAL deploy
OPTIONAL after_deploy
after_script

Configs 32-bit x86 @

Deps

visual studio 2010
qt4.x
boost
liblas

ENV Variables

LIBLAS_ROOT ==> D:\Liblas (bin, include, lib)
BOOST_INCLUDEDIR ==> include
BOOST_LIBDIR ==> lib

You then need to set the following two environment variables to point respectively to the path of the libraries and the headers

BOOST_LIBRARYDIR=C:\dev\libboost_1_54_0\lib32-msvc-10.0
BOOST_INCLUDEDIR=C:\dev\libboost_1_54_0

You also need to add in your PATH environment variable, the path to the Boost dll’s:

C:\dev\libboost_1_54_0\lib32-msvc-10.0

With other versions of Tom installers, the path to libraries may end with lib32 instead of lib32-msvc-10.0.

I selected C:\Qt\4.8.2 so QTDIR is set to C:\Qt\4.8.2

I add C:\Qt\4.8.2\bin to my PATH

C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\bin: cvtres.exe ==> cvtres1.exe

PDB what for? For Debugging. @

How to in Visual Studio

Tools->Options->Debugging->Symbols
and select checkbox “Microsoft Symbol Servers”

Load PDB, F5 ==> Control + F5

link err, failure to convert to COFF Incremental Linking: Yes ==> No

refs and see also

SVN @

# 1
svn update
svn status
svn diff
svn commit -m 'commit message'

# 2
svn merge ?
svn revert ?
svn resolve ?
# 3
svn log

VS Extensions @

VsVim
tssts

OpenGL: http://www.opengl.org/resources/libraries/glut/glutdlls37beta.zip @

glut.h ==> C:\Program Files (x86)\Microsoft SDKs\Windows\v7.0A\Include\gl
glut.lib glut32.lib ==> C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\lib
glut.dll glut32.dll ==> C:\Windows\System32

CMakeLists.txt Snippets @

set_target_properties( ${PROJECT_NAME} PROPERTIES VS_KEYWORD Qt4VSv1.0 )

set( CMAKE_COLOR_MAKEFILE ON )
set_property( GLOBAL PROPERTY USE_FOLDERS ON )

# Set the include directories
include_directories( ${CMAKE_SOURCE_DIR} )
include_directories( ${CMAKE_SOURCE_DIR}/src )
include_directories( ${CMAKE_CURRENT_BINARY_DIR} )

link_directories( ${CMAKE_BINARY_DIR} )

# Setup output directories
set( LIBRARY_OUTPUT_PATH
    ${PROJECT_BINARY_DIR}/bin
    CACHE
    PATH
    "Single directory for all libraries" )

set( EXECUTABLE_OUTPUT_PATH
    ${PROJECT_BINARY_DIR}/bin
    CACHE
    PATH
    "Single directory for all executables" )

add_definitions( -DUNICODE )
add_definitions( -D_CRT_SECURE_NO_WARNINGS )
add_definitions( -Wall )

# large address aware option setting
if( ${MINGW} )
    set( LARGEADDRESSAWARE "--large-address-aware" )
else(${MINGW})
    if( WIN32 )
        set( LARGEADDRESSAWARE "/LARGEADDRESSAWARE" )
    else( WIN32 )
        set( LARGEADDRESSAWARE " " )
    endif( WIN32 )
endif( ${MINGW} )

# this command finds Qt4 libraries and sets all required variables
# note that it's Qt4, not QT4 or qt4
find_package( Qt4 REQUIRED )

set( QT_USE_QTMAIN TRUE )
set( QT_USE_QTOPENGL TRUE )
set( QT_USE_QTXML TRUE )

# (QT_USE_FILE is a variable defined by FIND_PACKAGE( Qt4 ) that contains a
# path to CMake script)
include( ${QT_USE_FILE} )

set( RSCS img.qrc )

qt4_wrap_cpp( MOC_SRCS ${HDRS_FILES} )
qt4_add_resources( RSC_SRCS ${RSCS} )
qt4_wrap_ui( UI_HDRS ${UI_FILES} )

set( FILES_TO_TRANSLATE ${FILES_TO_TRANSLATE}
     ${SRCS_FILES} ${UI_FILES} ${HDRS_FILES} PARENT_SCOPE )

source_group( "UI Files" FILES ${UI_FILES} )
source_group( "Generated Files" FILES ${MOC_SRCS} ${UI_HDRS} ${RSC_SRCS} )
source_group( "Class Diagrams" FILES ${CD_FILES} )
source_group( "Resources" FILES ${RSCS} )

add_executable( ${PROJECT_NAME}
    ${SRCS_FILES} ${UI_FILES} ${HDRS_FILES}
    ${MOC_SRCS} ${UI_HDRS} ${RSC_SRCS} ${CD_FILES} )
set_source_files_properties( ${CD_FILES} PROPERTIES HEADER_FILE_ONLY TRUE )
target_link_libraries( ${PROJECT_NAME}
    ${QT_LIBRARIES} ${OPENGL_LIBRARY} ${GLUT_LIBRARIES} ${OpenCV_LIBS} )
set_target_properties( ${PROJECT_NAME} PROPERTIES
                       LINK_FLAGS ${LARGEADDRESSAWARE} )
set_target_properties( ${PROJECT_NAME} PROPERTIES
                       VS_KEYWORD Qt4VSv1.0 )

add_executable( example WIN32
                main.cpp mainwindow.cpp ${example_MOCS} ) # WIN32 needed

install( TARGETS ${PROJECT_NAME} DESTINATION bin )

# this command finds OpenCV libraries and sets all required variables
find_package( OpenCV REQUIRED )
include_directories( ${OPENCV_INCLUDE_DIR} )
include_directories( ${CMAKE_BINARY_DIR} )

find_package( OpenGL REQUIRED )
file( GLOB_RECURSE HDRS_FILES *.h *.hpp )
file( GLOB_RECURSE SRCS_FILES *.cpp )
file( GLOB_RECURSE UI_FILES *.ui )
file( GLOB CD_FILES *.cd )

add_subdirectory( src )

set (CMAKE_BUILD_TYPE Release) # cmake -DCMAKE_BUILD_TYPE=Debug .

uic ==> mainwindow.ui –> mainwindow.h
moc ==> mainwindow.h –> mainwindow.cpp
g++ ==>

some bash

uic mainwindow.ui  -o  ui_mainwindow.h
moc mainwindow.h   -o moc_mainwindow.cpp  ==> Q_OBJECT
rcc main.qrc       -o qrc_main.cpp
g++ main.cpp mainwindow.cpp  moc_mainwindow.cpp \
-IC:\Qt\4.8.4\include \
-LC:\Qt\4.8.4\lib \
-lQtCore4 \
-lQtGui4 \
-o main

# IF-ELSE-ENDIF
if (exp)
...
else (exp)
...
endif (exp)

# FOREACH
foreach (list)
...
endforeach (list)

# WHILE
while (cond)
...
endwhile (cond)

Headers & Libs

headers ==> include_directories –> PATH & LD_LIBRARY_PATH
libraries ==> find_library(good) or link_directories(bad)
include: *.h ==> -I in gcc
link dir: {*.so/*.dll/*.lib/*.dylib/...} ==> -L in gcc
link file: *.so/*.dll/*.lib/*.dylib/... ==> -l in gcc

Use FindXXXX.cmake & set ${CMAKE_MODULE_PATH} to

find_package( Qt4 REQUIRED ) # think of it as an #include

Or create your own finders

get_filename_component( ... )

# lib files
find_library( ... ) # CMAKE_LIBRARY_PATH

# header files
find_file( ... )    # CMAKE_INCLUDE_PATH

# MISC
find_program( ... )
try_compile( ... )
try_run( ... )

PkgConfig

UsePkgConfig.cmake
FindPkgConfig.cmake

Qt with CMake

project( pfrac )
find_package( QT4 REQUIRED )
include( ${QT_USE_FILE} )
SET( pfrac_SRCS main.cpp client.h client.cpp )
SET( pfrac_MOC_HEADERS client.h )
qt4_add_resoURCES( pfrac_SRCS
     ${PROJECT_SOURCE_DIR}/pfrac.qrc )
qt4_wrap_cpp( pfrac_MOC_SRCS
     ${pfrac_MOC_HEADERS} )
add_executable( pfrac ${pfrac_SRCS} ${pfrac_MOC_SRCS} )
target_link_libraries( pfrac ${QT_LIBRARIES} )

Congfigure file

set( VALUE 23 )
configure_file( conf.h.in conf.h )
check_include_file( unistd.h HAVE_UNISTD )

conf.h.in:

#cmakedefine VAL
#define KEY @VALUE@

conf.h:

#define VAL
#define KEY 23

*.h:

#ifdef VAL
    int keys[KEY];
#endif

#include "conf.h"
#ifdef HAVE_UNISTD
    // ...
#else
    // ...
#endif

MISC

# MESSAGE
message( [SEND_ERROR | STATUS | FATAL_ERROR] "message to display" ... )

# LINK
target_link_libraries( wakeup RELEASE ${SRC} )
target_link_libraries( wakeupd DEBUG ${SRC} )

# INSTALL
install( TARGETS ... RUNTIME DESTINATION bin LIBRARY DESTINATION lib )

# MACRO (text substitution)
macro (INSERT_INTO_MAP _KEY _VALUE)
  set ("MyMap_${_KEY}" "${_VALUE}")
endmacro (INSERT_INTO_MAP)

set( MyKey "foo" )
set( MyValue "bar" )
insert_into_map( "${MyKey}" "${MyValue}" )

# FUNCTION
...

# EXECUTE_PROCESS
execute_process( )

# TARGET
add_custom_targets

# CACHE
set( num 23 CACHE ) # use cached 'num' if possible, and save to it
set( num 23 CACHE FORCE ) # force overwrite Cache.

# POLICY (for Back/Forward?compatibility)
...

# Properties
cmake_minimum_required( ... )
option( ... )
get_cmake_property( ... )
get_target_property( ... )
set_target_property( ... )
set_source_files_properties( ... )

# Useful Varibles
cmake_binary_dir( build  dir )    CMAKE_CURRENT_BINARY_DIR
cmake_source_dir( source dir )    CMAKE_CURRENT_SOURCE_DIR

PROJECT_BINARY_DIR   EXECUTABLE_OUTPUT_PATH
PROJECT_SOURCE_DIR   LIBRARY_OUTPUT_PATH

$ENV{name}

MISC

*.ilk => incremental linker file
LD_LIBRARY_PATH ==> Link Dynamically Lib Path

CPack (for installer packaging)
CTest & CDash (for code testing & testing result displaying)

pdf2img @

PDF=$1
IMG=${PDF%.*}

convert              \
    -verbose         \
    -density 150     \
    -trim            \
    $PDF             \
    -quality 100     \
    -sharpen 0x1.0   \
    ${IMG}.jpg

see also:

# ppt -> pdf
libreoffice --headless --invisible --convert-to pdf *.ppt

# file -> pdf
unoconv -f pdf file

# crop pdf
pdfcrop file.pdf cropped.pdf

refs and see also

A.pdf -> A-{0,1}.jpg

后来，我建了一个 repo：district10/pdf2img: Convert PDF file to Images, via ImageMagick.。

再后来，我用 xpdf 处理 PDF · Issue #10 · district10/blog。

image magick @

raw2img

#!/bin/bash

echo start time: `date`

for i in *.raw;
do
    convert -size 5120x3840 -depth 8 gray:$i jpg/`basename $i .raw`.jpg
    mv $i raw/
done

echo end time: `date`

imagemagick:

!/bin/bash

for i in rotate shear roll hue saturation brightness gamma spiff dull \
         grayscale quantize despeckle reduceNoise addNoise sharpen blur \
         threshold edgedetect spread shade raise segment solarize swirl \
         implode wave oilpaint charcoal jpeg;
do
    convert main.jpg -preview ${i} -gravity south -box "#00000020" \
        -pointsize 36 -fill "#887ddd" -draw "text 0,0 '${i}'" out.${i}.jpg
done

montage out.*.jpg -tile 1x$(ls out.*.jpg | wc -l) -geometry 766x936 out.main.jpg

var fs = require('fs');
var gm = require('gm');

// resize and remove EXIF profile data
gm('img/600x300.jpg')
.resize(240, 240)
.noProfile()
.write('resized.png', function (err) {
  if (!err) { console.log('done'); }
});

curl @

$ curl -X POST -F file=@./package.json localhost:8090/gridfs
{
  "method": "POST",
  "url": "/gridfs",
  "header": {
    "user-agent": "curl/7.35.0",
    "host": "localhost:8090",
    "accept": "*/*",
    "content-length": "1022",
    "expect": "100-continue",
    "content-type": "multipart/form-data; boundary=------------------------72fd612aa595d9d6"
  }
}

$ curl -X POST -d @./package.json localhost:8090/gridfs
{
  "method": "POST",
  "url": "/gridfs",
  "header": {
    "user-agent": "curl/7.35.0",
    "host": "localhost:8090",
    "accept": "*/*",
    "content-length": "783",
    "content-type": "application/x-www-form-urlencoded"
  }
}

$ curl -X POST \
    -F file=@./package.json \
    -F file=@./upload.js localhost:8000/upload

awk, word frequency counter @

# wordfreq.awk --- print list of word frequencies

{
    $0 = tolower($0)    # remove case distinctions
    # remove punctuation
    gsub(/[^[:alnum:][:blank:]]/, " ", $0)
    for (i = 1; i <= NF; i++)
        freq[$i]++
}

END {
    for (word in freq)
        printf "%s\t%d\n", word, freq[word]
}

#!/bin/bash

FILE=$1

sed -e 's/\([A-Z]\)/ \L\1/g' $FILE | \
gawk -f wcf.awk | sort -k 2nr

read @

#/bin/bash

ADDTO="2015.md"
DATE=`date +%Y-%m-%d`

echo adding $1
echo \* \[ \] \[$DATE\] $1 >> $ADDTO
echo ===================================
echo Please read, and read with pleasure.

git add -A && git commit -m `date +%s` && git pull && git push

i3 window manager @

By pressing $mod+Enter, a new terminal will be opened. It will fill the whole space available on your screen.

Therefore, $mod+j is left, $mod+k is down, $mod+l is up and $mod+; is right. So, to switch between the terminals, use $mod+k or $mod+l. Of course, you can also use the arrow keys.

To split a window vertically, press $mod+v before you create the new window. To split it horizontally, press $mod+h.

To switch modes, press $mod+e for splith/splitv (it toggles), $mod+s for stacking and $mod+w for tabbed.

To display a window in fullscreen mode or to go out of fullscreen mode again, press $mod+f.

If an application does not provide a mechanism for closing (most applications provide a menu, the escape key or a shortcut like Control+w to close), you can press $mod+Shift+q to kill a window. For applications which support the WM_DELETE protocol, this will correctly close the application (saving any modifications or doing other cleanup). If the application doesn’t support the WM_DELETE protocol your X server will kill the window and the behaviour depends on the application.

$mod+num, goto workspace,

$mod+shift+num, move window to workspace.

To restart i3 in place (and thus get into a clean state if there is a bug, or to upgrade to a newer version of i3) you can use $mod+Shift+r.

To cleanly exit i3 without killing your X server, you can use $mod+Shift+e. By default, a dialog will ask you to confirm if you really want to quit.

You can toggle floating mode for a window by pressing $mod+Shift+Space. By dragging the window’s titlebar with your mouse you can move the window around. By grabbing the borders and moving them you can resize the window. You can also do that by using the [floating_modifier]. Another way to resize floating windows using the mouse is to right-click on the titlebar and drag.

/character-classes @

…	…	…	…
`/\i`	`\i`	`\i`	identifier character (see ‘isident’ option)
`/\I`	`\I`	`\I`	like `\i`, but excluding digits
`/\k`	`\k`	`\k`	keyword character (see ‘iskeyword’ option)
`/\K`	`\K`	`\K`	like `\k`, but excluding digits
`/\f`	`\f`	`\f`	file name character (see ‘isfname’ option)
`/\F`	`\F`	`\F`	like `\f`, but excluding digits
`/\p`	`\p`	`\p`	printable character (see ‘isprint’ option)
`/\P`	`\P`	`\P`	like `\p`, but excluding digits
`/\s`	`\s`	`\s`	whitespace character: and
`/\S`	`\S`	`\S`	non-whitespace character; opposite of
`/\d`	`\d`	`\d`	digit: `[0-9]`
`/\D`	`\D`	`\D`	non-digit: `[^0-9]`
`/\x`	`\x`	`\x`	hex digit: `[0-9A-Fa-f]`
`/\X`	`\X`	`\X`	non-hex digit: `[^0-9A-Fa-f]`
`/\o`	`\o`	`\o`	octal digit: `[0-7]`
`/\O`	`\O`	`\O`	non-octal digit: `[^0-7]`
`/\w`	`\w`	`\w`	word character: `[0-9A-Za-z_]`
`/\W`	`\W`	`\W`	non-word character: `[^0-9A-Za-z_]`
`/\h`	`\h`	`\h`	head of word character: `[A-Za-z_]`
`/\H`	`\H`	`\H`	non-head of word character: `[^A-Za-z_]`
`/\a`	`\a`	`\a`	alphabetic character: `[A-Za-z]`
`/\A`	`\A`	`\A`	non-alphabetic character: `[^A-Za-z]`
`/\l`	`\l`	`\l`	lowercase character: `[a-z]`
`/\L`	`\L`	`\L`	non-lowercase character: `[^a-z]`
`/\u`	`\u`	`\u`	uppercase character: `[A-Z]`
`/\U`	`\U`	`\U`	non-uppercase character `[^A-Z]`
`/\_`	`\_x`	`\_x`	where x is any of the characters above: character

see more at :h regexp

%s/pattern//gn, count of matches
%s/pattern//n, count of lines with matches
%s///n, count of current word
:10,50s/pattern//gn, line 10 to line 50
:s/\[\d\{,3\}\]//g, delete ``-like ref links in wikipedia
:%s/^$.*$(/\L\1/, cmake, lowercase commands

opetators @

bool operator == (const ref_ptr& rp) const { return (_ptr==rp._ptr); }
bool operator == (const T* ptr) const { return (_ptr==ptr); }
friend bool operator == (const T* ptr, const ref_ptr& rp) { return (ptr==rp._ptr); }

bool operator != (const ref_ptr& rp) const { return (_ptr!=rp._ptr); }
bool operator != (const T* ptr) const { return (_ptr!=ptr); }
friend bool operator != (const T* ptr, const ref_ptr& rp) { return (ptr!=rp._ptr); }

bool operator < (const ref_ptr& rp) const { return (_ptr<rp._ptr); }

// follows is an implmentation of the "safe bool idiom", details can be found at:
//   http://en.wikibooks.org/wiki/More_C%2B%2B_Idioms/Safe_bool
//   http://lists.boost.org/Archives/boost/2003/09/52856.php

private:
typedef T* ref_ptr::*unspecified_bool_type;

public:
// safe bool conversion
operator unspecified_bool_type() const { return valid()? &ref_ptr::_ptr : 0; }
#endif

T& operator*() const { return *_ptr; }
T* operator->() const { return _ptr; }
T* get() const { return _ptr; }

bool operator!() const   { return _ptr==0; } // not required
bool valid() const       { return _ptr!=0; }

/** release the pointer from ownership by this ref_ptr<>, decrementing the
 * objects refencedCount() via unref_nodelete() to prevent the Object
 * object from being deleted even if the reference count goes to zero.  Use
 * when using a local ref_ptr<> to an Object that you want to return from a
 * function/method via a C pointer, whilst preventing the normal ref_ptr<>
 * destructor from cleaning up the object. When using release() you are
 * implicitly expecting other code to take over management of the object,
 * otherwise a memory leak will result. */
T* release() { T* tmp=_ptr; if (_ptr) _ptr->unref_nodelete(); _ptr=0; return tmp; }

void swap(ref_ptr& rp) { T* tmp=_ptr; _ptr=rp._ptr; rp._ptr=tmp; }

If ... Else ... Paradigm @

Cognitive Bias

Name	Description
Ambiguity effect	The tendency to avoid options for which missing information makes the probability seem “unknown”.
Anchoring or focalism	The tendency to rely too heavily, or “anchor”, on one trait or piece of information when making decisions (usually the first piece of information that we acquire on that subject)
Anthropomorphism	The tendency to characterize animals, objects, and abstract concepts as possessing human-like traits, emotions, and intentions.
Attentional bias	The tendency of our perception to be affected by our recurring thoughts.
Automation bias	The tendency to excessively depend on automated systems which can lead to erroneous automated information overriding correct decisions.
Availability heuristic	The tendency to overestimate the likelihood of events with greater “availability” in memory, which can be influenced by how recent the memories are or how unusual or emotionally charged they may be.
Availability cascade	A self-reinforcing process in which a collective belief gains more and more plausibility through its increasing repetition in public discourse (or “repeat something long enough and it will become true”).
Backfire effect	When people react to disconfirming evidence by strengthening their beliefs.
Bandwagon effect	The tendency to do (or believe) things because many other people do (or believe) the same. Related to groupthink and herd behavior.
Base rate fallacy or Base rate neglect	The tendency to ignore base rate information (generic, general information) and focus on specific information (information only pertaining to a certain case).
Belief bias	An effect where someone’s evaluation of the logical strength of an argument is biased by the believability of the conclusion.
Bias blind spot	The tendency to see oneself as less biased than other people, or to be able to identify more cognitive biases in others than in oneself.
Cheerleader effect	The tendency for people to appear more attractive in a group than in isolation.
Choice-supportive bias	The tendency to remember one’s choices as better than they actually were.
Clustering illusion	The tendency to overestimate the importance of small runs, streaks, or clusters in large samples of random data (that is, seeing phantom patterns).
Confirmation bias	The tendency to search for, interpret, focus on and remember information in a way that confirms one’s preconceptions.
Congruence bias	The tendency to test hypotheses exclusively through direct testing, instead of testing possible alternative hypotheses.
Conjunction fallacy	The tendency to assume that specific conditions are more probable than general ones.
Conservatism (Bayesian)	The tendency to revise one’s belief insufficiently when presented with new evidence.
Contrast effect	The enhancement or reduction of a certain perception’s stimuli when compared with a recently observed, contrasting object.
Curse of knowledge	When better-informed people find it extremely difficult to think about problems from the perspective of lesser-informed people.
Declinism	The belief that a society or institution is tending towards decline. Particularly, it is the predisposition to view the past favourably and future negatively.
Decoy effect	Preferences for either option A or B changes in favor of option B when option C is presented, which is similar to option B but in no way better.
Denomination effect	The tendency to spend more money when it is denominated in small amounts (e.g., coins) rather than large amounts (e.g., bills).
Disposition effect	The tendency to sell an asset that has accumulated in value and resist selling an asset that has declined in value.
Distinction bias	The tendency to view two options as more dissimilar when evaluating them simultaneously than when evaluating them separately.
Dunning-Kruger effect	The tendency for unskilled individuals to overestimate their own ability and the tendency for experts to underestimate their own ability.
Duration neglect	The neglect of the duration of an episode in determining its value
Empathy gap	The tendency to underestimate the influence or strength of feelings, in either oneself or others.
Endowment effect	The tendency for people to demand much more to give up an object than they would be willing to pay to acquire it.
Essentialism	Categorizing people and things according to their essential nature, in spite of variations.[dubious – discuss]
Exaggerated expectation	Based on the estimates, real-world evidence turns out to be less extreme than our expectations (conditionally inverse of the conservatism bias).
Experimenter’s or expectation bias	The tendency for experimenters to believe, certify, and publish data that agree with their expectations for the outcome of an experiment, and to disbelieve, discard, or downgrade the corresponding weightings for data that appear to conflict with those expectations.
Focusing effect	The tendency to place too much importance on one aspect of an event.
Forer effect or Barnum effect	The observation that individuals will give high accuracy ratings to descriptions of their personality that supposedly are tailored specifically for them, but are in fact vague and general enough to apply to a wide range of people. This effect can provide a partial explanation for the widespread acceptance of some beliefs and practices, such as astrology, fortune telling, graphology, and some types of personality tests.
Framing effect	Drawing different conclusions from the same information, depending on how that information is presented
Frequency illusion	The illusion in which a word, a name, or other thing that has recently come to one’s attention suddenly seems to appear with improbable frequency shortly afterwards (not to be confused with the recency illusion or selection bias). Colloquially, this illusion is known as the Baader-Meinhof Phenomenon.
Functional fixedness	Limits a person to using an object only in the way it is traditionally used.
Gambler’s fallacy	The tendency to think that future probabilities are altered by past events, when in reality they are unchanged. The fallacy arises from an erroneous conceptualization of the law of large numbers. For example, “I’ve flipped heads with this coin five times consecutively, so the chance of tails coming out on the sixth flip is much greater than heads.”
Hard–easy effect	Based on a specific level of task difficulty, the confidence in judgments is too conservative and not extreme enough
Hindsight bias	Sometimes called the “I-knew-it-all-along” effect, the tendency to see past events as being predictable at the time those events happened.
Hot-hand fallacy	The “hot-hand fallacy” (also known as the “hot hand phenomenon” or “hot hand”) is the fallacious belief that a person who has experienced success with a random event has a greater chance of further success in additional attempts.
Hyperbolic discounting	Discounting is the tendency for people to have a stronger preference for more immediate payoffs relative to later payoffs. Hyperbolic discounting leads to choices that are inconsistent over time –people make choices today that their future selves would prefer not to have made, despite using the same reasoning. Also known as current moment bias, present-bias, and related to Dynamic inconsistency.
Identifiable victim effect	The tendency to respond more strongly to a single identified person at risk than to a large group of people at risk.
Illusion of control	The tendency to overestimate one’s degree of influence over other external events.
Illusion of validity	Belief that furtherly acquired information generates additional relevant data for predictions, even when it evidently does not.
Illusory correlation	Inaccurately perceiving a relationship between two unrelated events.
Impact bias	The tendency to overestimate the length or the intensity of the impact of future feeling states.
Information bias	The tendency to seek information even when it cannot affect action.
Insensitivity to sample size	The tendency to under-expect variation in small samples.
Irrational escalation	The phenomenon where people justify increased investment in a decision, based on the cumulative prior investment, despite new evidence suggesting that the decision was probably wrong. Also known as the sunk cost fallacy.
Less-is-better effect	The tendency to prefer a smaller set to a larger set judged separately, but not jointly.
Loss aversion	The disutility of giving up an object is greater than the utility associated with acquiring it. (see also Sunk cost effects and endowment effect).
Mere exposure effect	The tendency to express undue liking for things merely because of familiarity with them.
Money illusion	The tendency to concentrate on the nominal value (face value) of money rather than its value in terms of purchasing power.
Moral credential effect	The tendency of a track record of non-prejudice to increase subsequent prejudice.
Negativity effect	The tendency of people, when evaluating the causes of the behaviors of a person they dislike, to attribute their positive behaviors to the environment and their negative behaviors to the person’s inherent nature.
Negativity bias	Psychological phenomenon by which humans have a greater recall of unpleasant memories compared with positive memories.
Neglect of probability	The tendency to completely disregard probability when making a decision under uncertainty.
Normalcy bias	The refusal to plan for, or react to, a disaster which has never happened before.
Not invented here	Aversion to contact with or use of products, research, standards, or knowledge developed outside a group. Related to IKEA effect.
Observer-expectancy effect	When a researcher expects a given result and therefore unconsciously manipulates an experiment or misinterprets data in order to find it (see also subject-expectancy effect).
Omission bias	The tendency to judge harmful actions as worse, or less moral, than equally harmful omissions (inactions).
Optimism bias	The tendency to be over-optimistic, overestimating favorable and pleasing outcomes (see also wishful thinking, valence effect, positive outcome bias).
Ostrich effect	Ignoring an obvious (negative) situation.
Outcome bias	The tendency to judge a decision by its eventual outcome instead of based on the quality of the decision at the time it was made.
Overconfidence effect	Excessive confidence in one’s own answers to questions. For example, for certain types of questions, answers that people rate as “99% certain” turn out to be wrong 40% of the time.
Pareidolia	A vague and random stimulus (often an image or sound) is perceived as significant, e.g., seeing images of animals or faces in clouds, the man in the moon, and hearing non-existent hidden messages on records played in reverse.
Pessimism bias	The tendency for some people, especially those suffering from depression, to overestimate the likelihood of negative things happening to them.
Planning fallacy	The tendency to underestimate task-completion times.
Post-purchase rationalization	The tendency to persuade oneself through rational argument that a purchase was good value.
Pro-innovation bias	The tendency to have an excessive optimism towards an invention or innovation’s usefulness throughout society, while often failing to identify its limitations and weaknesses.
Pseudocertainty effect	The tendency to make risk-averse choices if the expected outcome is positive, but make risk-seeking choices to avoid negative outcomes.
Reactance	The urge to do the opposite of what someone wants you to do out of a need to resist a perceived attempt to constrain your freedom of choice (see also Reverse psychology).
Reactive devaluation	Devaluing proposals only because they purportedly originated with an adversary.
Recency illusion	The illusion that a word or language usage is a recent innovation when it is in fact long-established (see also frequency illusion).
Regressive bias	A certain state of mind wherein high values and high likelihoods are overestimated while low values and low likelihoods are underestimated.
Restraint bias	The tendency to overestimate one’s ability to show restraint in the face of temptation. Rhyme as reason effect \| Rhyming statements are perceived as more truthful. A famous example being used in the O.J Simpson trial with the defense’s use of the phrase “If the gloves don’t fit, then you must acquit.”
Risk compensation / Peltzman effect	The tendency to take greater risks when perceived safety increases.
Selective perception	The tendency for expectations to affect perception.
Semmelweis reflex	The tendency to reject new evidence that contradicts a paradigm.
Social comparison bias	The tendency, when making hiring decisions, to favour potential candidates who don’t compete with one’s own particular strengths.
Social desirability bias	The tendency to over-report socially desirable characteristics or behaviours in oneself and under-report socially undesirable characteristics or behaviours.
Status quo bias	The tendency to like things to stay relatively the same (see also loss aversion, endowment effect, and system justification).
Stereotyping	Expecting a member of a group to have certain characteristics without having actual information about that individual.
Subadditivity effect	The tendency to judge probability of the whole to be less than the probabilities of the parts.
Subjective validation	Perception that something is true if a subject’s belief demands it to be true. Also assigns perceived connections between coincidences.
Survivorship bias	Concentrating on the people or things that “survived” some process and inadvertently overlooking those that didn’t because of their lack of visibility.
Time-saving bias	Underestimations of the time that could be saved (or lost) when increasing (or decreasing) from a relatively low speed and overestimations of the time that could be saved (or lost) when increasing (or decreasing) from a relatively high speed.
Third-person effect	Belief that that mass communicated media messages have a greater effect on others than on themselves.
Triviality / Parkinson’s Law of	The tendency to give disproportionate weight to trivial issues. Also known as bikeshedding, this bias explains why an organization may avoid specialized or complex subjects, such as the design of a nuclear reactor, and instead focus on something easy to grasp or rewarding to the average participant, such as the design of an adjacent bike shed.
Unit bias	The tendency to want to finish a given unit of a task or an item. Strong effects on the consumption of food in particular.
Weber–Fechner law	Difficulty in comparing small differences in large quantities.
Well travelled road effect	Underestimation of the duration taken to traverse oft-traveled routes and overestimation of the duration taken to traverse less familiar routes.
Zero-risk bias	Preference for reducing a small risk to zero over a greater reduction in a larger risk.
Zero-sum heuristic	Intuitively judging a situation to be zero-sum (i.e., that gains and losses are correlated). Derives from the zero-sum game in game theory, where wins and losses sum to zero. The frequency with which this bias occurs may be related to the social dominance orientation personality factor

refs and see also

Language Tags in HTML and XML | W3C

vim @

:b <TAB>, list buffers.
:b PATTERN<TAB>, list buffers.
:set readonly
:set nomodifable
:setlocal textwidth=70
:ls, or :buffers, :files, :b 5
:bdelete
:help ctrl-w
:ball, open all buffers in current window
ctrl-w o, leave only one window
:help 'switchbuf'
:rew[ind], :E, :e .
ctrl-o, older position
in dir listing:
- o, v: open, open vertically
- t: tab open
- p: preview window
ctrl-o, ctrl-i, back and forth
``, last position, `., last edit, read more :help jumplist
:Sex .

我不是为她出发，却为她到达。 @

绝大部分 20 左右的小伙子，心里想的都是付出、责任。他们可能没那么多花招，但是
愿意做一切喜欢的女孩希望的事情。

20 左右的小姑娘，心里只想着享受，每天纠结于霸道总裁还是知性暖男，韩国偶吧还
是欧美猛男。总说再不疯狂就老了，总想着轰轰烈烈的恋爱。

这时的小伙子想的都是奋斗、闯荡，他们会为自己不如其他小伙子而羞愧，渴望着有
个公主等着自己呵护，认为通向城堡的路布满荆棘，还有可怕的巨龙。

他还没有把剑擦亮，却看到公主坐着小马车寻欢作乐去了。

“你能像吟游诗人一样天天为我讲故事么？”

“你能像杂技演员一样天天逗我笑么？”

“当我孤独的时候你却不在我身边，但是侍卫长却能温暖我”

“我和花花公子在一起真的很开心，他带我四处旅游、喝红酒、吃大餐”

我能理解，真的。可能你并不是我想象中的公主，但我还是会踏上这条荆棘之路。

因为我们，是英雄啊

有一天，在路边的田地里会有一个发髻上插着野花的姑娘，粗糙的手，小麦色的肌肤。

她不美丽，却愿意对我笑。

我不是为她出发，却为她到达。

两条有意思的回复：

公主不是夜总会里的么，600 一个，包夜 1000 多。

20 岁左右的姑娘遇到一个穷小伙。
她觉得自己喜欢一个人，养他都行。
然后姑娘读博去了。
小伙子回家乡了工作了。
小伙子很快结婚了。
姑娘成了大龄单身女博士。
同龄的男博士们都去找 20 的小姑娘了。
并不是所有 20 岁的小姑娘都在寻欢作乐，有的搞学习，做实验去了。
然后就浪费了青春，成了被人嫌弃的女博士。
为什么你一开始目光都在小公主身上，到最后才发现小村姑呢。
其实小村姑很多，长得不好看，在这个看脸的社会，你根本看不到。

scientific-python-lectures @

To create an 800x400 pixel, 100 dots-per-inch figure, we can do:

fig = plt.figure(figsize=(8,4), dpi=100)

# code
fig.savefig("filename.png") # fig.savefig("filename.png", dpi=200)

# code
fig, axes = plt.subplots(figsize=(12,3))

axes.plot(x, y, 'r')
axes.set_xlabel('x')
axes.set_ylabel('y')
axes.set_title('title');

axes.legend(["curve1", "curve2", "curve3"]);

ax.legend(loc=0) # let matplotlib decide the optimal location
ax.legend(loc=1) # upper right corner
ax.legend(loc=2) # upper left corner
ax.legend(loc=3) # lower left corner
ax.legend(loc=4) # lower right corner
# .. many more options are available

# MATLAB style line color and style
ax.plot(x, x**2, 'b.-') # blue line with dots
ax.plot(x, x**3, 'g--') # green dashed line


# Python style
fig, ax = plt.subplots()

ax.plot(x, x+1, color="red", alpha=0.5) # half-transparant red
ax.plot(x, x+2, color="#1155dd")        # RGB hex code for a bluish color
ax.plot(x, x+3, color="#15cc55")        # RGB hex code for a greenish color

# plot range
axes.axis('tight')
axes.set_yscale("log")

axes.set_ylim([0, 60])
axes.set_xlim([2, 5])

ax.set_xticks([1, 2, 3, 4, 5])
ax.set_xticklabels([r'$\alpha$', r'$\beta$', r'$\gamma$', r'$\delta$', r'$\epsilon$'],
                   fontsize=18)

# scientific notation
fig, ax = plt.subplots(1, 1)

ax.plot(x, x**2, x, np.exp(x))
ax.set_title("scientific notation")

ax.set_yticks([0, 50, 100, 150])

from matplotlib import ticker
formatter = ticker.ScalarFormatter(useMathText=True)
formatter.set_scientific(True)
formatter.set_powerlimits((-1,1))
ax.yaxis.set_major_formatter(formatter)

# distance between x and y axis and the numbers on the axes
matplotlib.rcParams['xtick.major.pad'] = 5
matplotlib.rcParams['ytick.major.pad'] = 5

fig, ax = plt.subplots(1, 1)

ax.plot(x, x**2, x, np.exp(x))
ax.set_yticks([0, 50, 100, 150])

ax.set_title("label and axis spacing")

# padding between axis label and axis numbers
ax.xaxis.labelpad = 5
ax.yaxis.labelpad = 5

ax.set_xlabel("x")
ax.set_ylabel("y");

pd.read_clipboard()

Python Regex @

> import re
> str = 'Zhouy a Python learner and i am now learning Regular Expression'
> m = re.match('(\w+)\s',str)
> print m
> print m.group(0)
<MatchObject object>
Zhouy

re.match, re.search, re.split, re.findAll, re.replace,

> s = '100 NORTH BROAD ROAD'
> s_new = s[:-4] + s[-4:].replace('ROAD', 'RD.')
> print s_new
100 NORTH BROAD RD.

> import re
> s = '100 NORTH BROAD ROAD'
> s_new = re.sub('ROAD$', 'RD.', s)
> print s_new
Out: 100 NORTH BROAD RD.

import re
pattern = '^M{0,3}$'
print re.search(pattern, 'M')

带有内联注释 (Inline Comments) 的正则表达式

pattern = """
^ # beginning of string
M{0,3} # thousands - 0 to 3 M's
(CM|CD|D?C{0,3}) # hundreds - 900 (CM), 400 (CD), 0-300 (0 to 3 C's),
# or 500-800 (D, followed by 0 to 3 C's)
(XC|XL|L?X{0,3}) # tens - 90 (XC), 40 (XL), 0-30 (0 to 3 X's),
# or 50-80 (L, followed by 0 to 3 X's)
(IX|IV|V?I{0,3}) # ones - 9 (IX), 4 (IV), 0-3 (0 to 3 I's),
# or 5-8 (V, followed by 0 to 3 I's)
$ # end of string
"""
print re.search(pattern, 'M', re.VERBOSE)

> import re
> print re.search(r'^(\d{3})-(\d{3})-(\d{4})$','800-555-1212').groups()
800 555 1212

import re
print re.search(r'^(\d{3})-(\d{3})-(\d{4})-(\d+)$','800-555-1212-1234').groups()
print re.search(r'^(\d{3})-(\d{3})-(\d{4})-(\d+)$','800 555 1212 1234')

\D 匹配任意字符，除了数字位，+ 表示“1 个或者多个”

import re
def plural(noun):
    if re.search('[sxz]$', noun):
        return re.sub('$', 'es', noun)
    elif re.search('[^aeioudgkprt]h$', noun):
        return re.sub('$', 'es', noun)
    elif re.search('[^aeiou]y$', noun):
        return re.sub('y$', 'ies', noun)
    else:
        return noun + 's'

Python正则表达式指南 - AstralWind - 博客园 @: 与大多数编程语言相同，正则表达式里使用 \ 作为转义字符，这就可能造成反斜杠困扰。假如你需要匹配文本中的字符 \，那么使用编程语言表示的正则表达式里将需要4个反斜杠 \\\\：前两个和后两个分别用于在编程语言里转义成反斜杠，转换成两个反斜杠后再在正则表达式里转义成一个反斜杠。Python 里的原生字符串很好地解决了这个问题，这个例子中的正则表达式可以使用 r"\\" 表示。同样，匹配一个数字的"\\d" 可以写成 r"\d"。有了原生字符串，你再也不用担心是不是漏写了反斜杠，写出来的表达式也更直观。

Python2 & Python3 on Windows: python3.bat @

@ echo off
C:\Python34\python.exe %*

附 In My Secret Life 的歌词： @

I saw you this morning.
You were moving so fast.
Can't seem to loosen my grip
On the past.
And I miss you so much.
There's no one in sight.
And we're still making love
In My Secret Life.

I smile when I'm angry.
I cheat and I lie.
I do what I have to do
To get by.
But I know what is wrong,
And I know what is right.
And I'd die for the truth
In My Secret Life.

Hold on, hold on, my brother.
My sister, hold on tight.
I finally got my orders.
I'll be marching through the morning,
Marching through the night,
Moving cross the borders
Of My Secret Life.

Looked through the paper.
Makes you want to cry.
Nobody cares if the people
Live or die.
And the dealer wants you thinking
That it's either black or white.
Thank G-d it's not that simple
In My Secret Life.

I bite my lip.
I buy what I'm told:
From the latest hit,
To the wisdom of old.
But I'm always alone.
And my heart is like ice.
And it's crowded and cold
In My Secret Life.

True Table @

0            (F F F F)(p, q)            ⊥            false, Opq            Contradiction
1            (F F F T)(p, q)            NOR            p ↓ q, Xpq            Logical NOR
2            (F F T F)(p, q)            \nleftarrow            p \nleftarrow q, Mpq            Converse nonimplication
3            (F F T T)(p, q)            ¬p, ~p            ¬p, Np, Fpq            Negation
4            (F T F F)(p, q)            \nrightarrow            p \nrightarrow q, Lpq            Material nonimplication
5            (F T F T)(p, q)            ¬q, ~q            ¬q, Nq, Gpq            Negation
6            (F T T F)(p, q)            XOR            p ⊕ q, Jpq            Exclusive disjunction
7            (F T T T)(p, q)            NAND            p ↑ q, Dpq            Logical NAND
8            (T F F F)(p, q)            AND            p ∧ q, Kpq            Logical conjunction
9            (T F F T)(p, q)            XNOR            p If and only if q, Epq            Logical biconditional
10            (T F T F)(p, q)            q            q, Hpq            Projection function
11            (T F T T)(p, q)            p \rightarrow q            if p then q, Cpq            Material implication
12            (T T F F)(p, q)            p            p, Ipq            Projection function
13            (T T F T)(p, q)            p \leftarrow q            p if q, Bpq            Converse implication
14            (T T T F)(p, q)            OR            p ∨ q, Apq            Logical disjunction
15            (T T T T)(p, q)            ⊤            true, Vpq            Tautology

Eye exercise for speed reading: @

Close your eyes. Do this sitting up to prevent you from falling asleep.

Relax your body. This can help relax your eyes.

Rub your eyes. Rub your eyes very gently, as if almost tickling them.

Relax your face. move your jaw side to side. Make sure you are not pressing your eyebrows together. Relax your cheeks and forehead.

Try To keep your eyes closed during this process.

Gently open your eyes when you are done. try to barely open them and focus on your eyelids. Follow them up and as you look at your eyelids your eyes will open up.

Wash eyes with cold water frequently.

Try “pushing” your nose down, this will pull your eyes down with the rest of the face

refs and see also

UrbanDictionary 是一个用户定义的单词本网站。 @

Roza

Roza means simply beautiful. A girl who has beautiful hair, gorgeous, big eyes and a smile that could brighten the ocean.

She looks gorgeous even in the morning or without any makeup on. Everytime you look at her, she stuns you with her looks n by the way she looks at you.

She is like a rose, closed in the beginning but if you give her time n nurture her, she will blossom into a mesmerizing beauty, who u feel blessed to have by your side.

She is smart n amazing just the way she is. The girl of your dreams, she is wanted n appreciated by everyone. She is all you could wish for.

Guy 1: she is so pretty !!!
Guy 2: yeah that she is..cuz she is Roza …guys usually drool over her but she is not just like any other pretty girl …she is different yet amazing.
Guy 1: yeah, thats cuz she is Roza i guess Just as beautiful as her name :)

Vagina

a tasty treat

my vagina smells like sugarcane but taste like flowers

Pierre de Fermat @

Pierre de Fermat

Pierre de Fermat (French: [pjɛːʁ dəfɛʁma]; 17 August 1601 – 12 January 1665) was a French lawyer at the Parlement of Toulouse, France, and a mathematician who is given credit for early developments that led to infinitesimal calculus, including his technique of adequality. In particular, he is recognized for his discovery of an original method of finding the greatest and the smallest ordinates of curved lines, which is analogous to that of the differential calculus, then unknown, and his research into number theory. He made notable contributions to analytic geometry, probability, and optics. He is best known for Fermat’s Last Theorem, which he described in a note at the margin of a copy of Diophantus’ Arithmetica.

Johannes Kepler @

A 1610 portrait of Johannes Kepler by an unknown artist

Johannes Kepler (German: [ˈkɛplɐ]; December 27, 1571 – November 15, 1630) was a German mathematician, astronomer, and astrologer. A key figure in the 17th century scientific revolution, he is best known for his laws of planetary motion, based on his works Astronomia nova, Harmonices Mundi, and Epitome of Copernican Astronomy. These works also provided one of the foundations for Isaac Newton’s theory of universal gravitation.

During his career, Kepler was a mathematics teacher at a seminary school in Graz, Austria, where he became an associate of Prince Hans Ulrich von Eggenberg. Later he became an assistant to astronomer Tycho Brahe, and eventually the imperial mathematician to Emperor Rudolf II and his two successors Matthias and Ferdinand II. He was also a mathematics teacher in Linz, Austria, and an adviser to General Wallenstein. Additionally, he did fundamental work in the field of optics, invented an improved version of the refracting telescope (the Keplerian Telescope), and mentioned the telescopic discoveries of his contemporary Galileo Galilei.

Kepler lived in an era when there was no clear distinction between astronomy and astrology, but there was a strong division between astronomy (a branch of mathematics within the liberal arts) and physics (a branch of natural philosophy). Kepler also incorporated religious arguments and reasoning into his work, motivated by the religious conviction and belief that God had created the world according to an intelligible plan that is accessible through the natural light of reason. Kepler described his new astronomy as “celestial physics”, as “an excursion into Aristotle’s Metaphysics”, transforming the ancient tradition of physical cosmology by treating astronomy as part of a universal mathematical physics.

Richard Dedekind @

East German stamp from 1981, commemorating Richard Dedekind.

Julius Wilhelm Richard Dedekind (6 October 1831 – 12 February 1916) was a German mathematician who made important contributions to abstract algebra (particularly ring theory), algebraic number theory and the definition of the real numbers.

Dedekind’s theorem states that if there existed a one-to-one correspondence between two sets, then Dedekind said that the two sets were “similar”. He invoked similarity to give the first precise definition of an infinite set: a set is infinite when it is “similar to a proper part of itself,” in modern terminology, is equinumerous to one of its proper subsets. Thus the set N of natural numbers can be shown to be similar to the subset of N whose members are the squares of every member of N, (N →N2):

N    1  2  3  4  5  6  7  8  9  10 ...
         ↓
N2   1  4  9  16 25 36 49 64 81 100 ...

Sir George Stokes, 1st Baronet @

Sir George Gabriel Stokes, 1st Baronet, PRS (/stoʊks/; 13 August 1819 – 1 February 1903), was a mathematician, physicist, politician and theologian. Born in Ireland, Stokes spent all of his career at University of Cambridge, where he served as the Lucasian Professor of Mathematics from 1849 until his death in 1903. Stokes made seminal contributions to fluid dynamics (including the Navier–Stokes equations), optics, and mathematical physics (including the first version of what is now known as Stokes’ theorem). He was secretary, then president, of the Royal Society.

René Descartes @

René Descartes (/ˈdeɪˌkɑrt/, French: [ʁəne dekaʁt], 31 March 1596 – 11 February 1650) was a French philosopher, mathematician and writer who spent most of his life in the Dutch Republic. He has been dubbed the father of modern philosophy, and much subsequent Western philosophy is a response to his writings, which are studied closely to this day. In particular, his Meditations on First Philosophy continues to be a standard text at most university philosophy departments. Descartes’ influence in mathematics is equally apparent; the Cartesian coordinate system — allowing reference to a point in space as a set of numbers, and allowing algebraic equations to be expressed as geometric shapes in a two-dimensional coordinate system (and conversely, shapes to be described as equations) — was named after him. He is credited as the father of analytical geometry, the bridge between algebra and geometry, crucial to the discovery of infinitesimal calculus and analysis. Descartes was also one of the key figures in the scientific revolution and has been described as an example of genius. He refused to accept the authority of previous philosophers and also refused to accept the obviousness of his own senses.

William Thomson, 1st Baron Kelvin @ @

Lord Kelvin by Hubert von Herkomer

William Thomson, 1st Baron Kelvin (/ˈkɛlvɪn/; 26 June 1824 – 17 December 1907) was an Irish mathematical physicist and engineer who was born in Belfast in 1824. At the University of Glasgow he did important work in the mathematical analysis of electricity and formulation of the first and second laws of thermodynamics, and did much to unify the emerging discipline of physics in its modern form. He worked closely with mathematics professor Hugh Blackburn in his work. He also had a career as an electric telegraph engineer and inventor, which propelled him into the public eye and ensured his wealth, fame and honour. For his work on the transatlantic telegraph project he was knighted by Queen Victoria, becoming Sir William Thomson. He had extensive maritime interests and was most noted for his work on the mariner’s compass, which had previously been limited in reliability.

Absolute temperatures are stated in units of kelvin in his honour. While the existence of a lower limit to temperature (absolute zero) was known prior to his work, Lord Kelvin is widely known for determining its correct value as approximately −273.15 degree Celsius or −459.67 degree Fahrenheit.

AFI’s 100 Years… 100 Movie Quotes (AFI: American Film Institute) @

“Frankly, my dear, I don’t give a damn.” Gone with the Wind
“I’m going to make him an offer he can’t refuse.” The Godfather
“You don’t understand! I coulda had class. I coulda been a contender. I could’ve been somebody, instead of a bum, which is what I am.” On the Waterfront
“Toto, I’ve got a feeling we’re not in Kansas anymore.” The Wizard of Oz
“Here’s looking at you, kid.” Casablanca
“Go ahead, make my day.” Sudden Impact
“All right, Mr. DeMille, I’m ready for my close-up.” Sunset Boulevard
“Fasten your seatbelts. It’s going to be a bumpy night.” All About Eve
“You talkin’ to me?” Texi Driver
“What we’ve got here is failure to communicate” Cool Hand Luke
“I love the smell of napalm (凝固汽油弹) in the morning.” * Apocalypse Now*
“Love means never having to say you’re sorry.” Love Story
“The stuff that dreams are made of.” The Maltese Falcon
“E.T. phone home.” E.T. the Extra-Terrestrial
“They call me Mister Tibbs!” In the Heat of the Night
“Rosebud.” Citizen Kane
“Made it, Ma! Top of the world!” White Heat
“I’m as mad as hell, and I’m not going to take this anymore!” Network
“Louis, I think this is the beginning of a beautiful friendship.” Casablanca
“A census taker once tried to test me. I ate his liver with some fava beans (['fa:və] 蚕豆) and a nice Chianti ([ki'ænti] 基安蒂红葡萄酒).” The Silence of the Lambs
“Bond. James Bond.” Dr. No
“There’s no place like home.” Sunset Boulevard
“I am big! It’s the pictures that got small.” Sunset Boulevard
“Show me the money!” Jerry Maguire
“Why don’t you come up sometime and see me?” She Done Him Wrong
“I’m walking here! I’m walking here!” Midnight Cowboy
“Play it, Sam. Play ‘As Time Goes By.’” Casablanca
“You can’t handle the truth!” A Few Good Men
“I want to be alone.” Grand Hotel
“After all, tomorrow is another day!” Gone with the Wind
“Round up the usual suspects.” Casablanca
“I’ll have what she’s having.” When Harry Met Sally…
“You know how to whistle, don’t you, Steve? You just put your lips together and blow.” To Have and Have Not
“You’re gonna need a bigger boat.” Jaws
“Badges? We ain’t got no badges! We don’t need no badges! I don’t have to show you any stinking badges!” The Treasure of the Sierra Madre
“I’ll be back.” The Terminator
“Today, I consider myself the luckiest man on the face of the Earth.” The Pride of Yankees
“If you build it, he will come.” Field of Dreams
“Mama always said life was like a box of chocolates. You never know what you’re gonna get.” Forrest Gump
“We rob banks.” Bonnie and Clyde
“Plastics.” The Graduate
“We’ll always have Paris.” Casablanca
“I see dead people.” The Sixth Sense
“Stella! Hey, Stella!” A Streetcar Named Desire
“Oh, Jerry, don’t let’s ask for the moon. We have the stars.” Now, Voyager
“Shane. Shane. Come back!” Shane
“Well, nobody’s perfect.” Some Like It Hot
“It’s alive! It’s alive!” Frankenstein
“Houston, we have a problem.” Apollo 13
“You’ve got to ask yourself one question: ‘Do I feel lucky?’ Well, do ya, punk?” Dirty Harry
“You had me at ‘hello.’” Jerry Maguire
“One morning I shot an elephant in my pajamas. How he got in my pajamas, I don’t know.” Animal Crackers
“There’s no crying in baseball!” A League of Their Own
“La-dee-da, la-dee-da.” Annie Hall
“A boy’s best friend is his mother.” Psycho
“Greed, for lack of a better word, is good.” Wall Street
“Keep your friends close, but your enemies closer.” The Godfather Part II
“As God is my witness, I’ll never be hungry again.” Gone with the Wind
“Well, here’s another nice mess you’ve gotten me into!” Sons of the Desert
“Say ‘hello’ to my little friend!” Scarface
“What a dump.” Beyond the Forest
“Mrs. Robinson, you’re trying to seduce me. Aren’t you?” The Graduate
“Gentlemen, you can’t fight in here! This is the War Room!” Dr. Strangelove or: How I Learned to Stop Worrying and Love the Bomb
“Elementary, my dear Watson.” The Adventures of Sherlock Holmes
“Get your stinking paws off me, you damned dirty ape.” Planet of the Apes
“Of all the gin joints in all the towns in all the world, she walks into mine.” Casablanca
“Here’s Johnny!” The Shining
“They’re here!” Poltergeist
“Is it safe?” Marathon Man
“Wait a minute, wait a minute. You ain’t heard nothin’ yet!” The Jazz Singer
“No wire hangers, ever!” Mommie Dearest
“Mother of mercy, is this the end of Rico?” Little Caesar
“Forget it, Jake, it’s Chinatown.” Chinatown
“I have always depended on the kindness of strangers.” A Streetcar Named Desire
“Hasta la vista, baby.” Terminator 2: Judgment Day
“Soylent Green is people!” Soylent Green
“Open the pod bay doors please, HAL.” 2001: A Space Odyssey
Striker: “Surely you can’t be serious.” Rumack: “I am serious…and don’t call me Shirley.” Airplane!
“Yo, Adrian!” Rocky
“Hello, gorgeous.” Funny Girl
“Toga! Toga!” National Lampoon’s Animal House
“Listen to them. Children of the night. What music they make.” Dracula
“Oh, no, it wasn’t the airplanes. It was Beauty killed the Beast.” King Kong
“My precious.” The Lord of the Rings: The Two Towers
“Attica! Attica!” Dog Day Afternoon
“Sawyer, you’re going out a youngster, but you’ve got to come back a star!” 42nd Street
“Listen to me, mister. You’re my knight in shining armor. Don’t you forget it. You’re going to get back on that horse, and I’m going to be right behind you, holding on tight, and away we’re gonna go, go, go!” On Golden Pond
“Tell ’em to go out there with all they got and win just one for the Gipper.” Knute Rockne, All American
“A martini. Shaken, not stirred.” Godfather
“Who’s on first?” The Naughty Nineties
“Cinderella story. Outta nowhere. A former greenskeeper, now, about to become the Masters champion. It looks like a mirac…It’s in the hole! It’s in the hole! It’s in the hole!” Caddyshack
“Life is a banquet, and most poor suckers are starving to death!” Auntie Mame
“I feel the need—the need for speed!” Top Gun
“Carpe diem. Seize the day, boys. Make your lives extraordinary.” Dead Poets Society
“Snap out of it!” Moonstruck
“My mother thanks you. My father thanks you. My sister thanks you. And I thank you.” Yankee Doodle Dandy
“Nobody puts Baby in a corner.” Dirty Dancing
“I’ll get you, my pretty, and your little dog too!” The Wizard Oz
“I’m the king of the world!” Titanic

More quotes

“曾经有一份真诚的爱情摆在我的面前，我没有珍惜，等到失去的时候才追悔莫及，人世间最痛苦的事情莫过于此。如果上天能够给我一个重新来过的机会，我会对那个女孩子说三个字：‘我爱你’。如果非要给这份爱加上一个期限，我希望是，一万年。” 大话西游
你可以说我是跑龙套的，但是你不可以说我是“臭跑龙套”的！ 喜剧之王
所以说做妖就像做人一样，要有仁慈的心，有了仁慈的心，就不再妖，是人妖。 大话西游
不是我喜欢打架，是有很多人喜欢被我打！ 鹿鼎记
“你那忧郁的眼神,唏嘘的胡渣子,神呼奇迹的刀法,还有那杯晶莹透亮的马蒂尼,都掩饰不住你的出众,但是再怎么出众也要把过夜费付了吧” 零零柒
“准确的说，我是一个演员。”
你可以叫我“跑龙套的”，但不可以前面不要加“死”字！！！！ 喜剧之王
实在令人太失望。听到你的声音，我还以为你是一个很有感性，很有电影幻想的人。看你这一身造型，就知道你太没有内涵了 92家有喜事
喂!你介不介意把裤子拉高一点,让我看看你的腿? 少林足球
大不了我发个毒誓，如果以后我再赌钱的话，就让天下最丑的女人夜夜轮奸，直到体无完肤，摇摇欲坠为止，这样可以了吧！ 唐伯虎点秋香
阿飞正传*：我听别人说这世界上有一种鸟是没有脚的，它只能一直飞呀飞呀，飞累了就在风里面睡觉，这种鸟一辈子只能下地一次，那边一次就是它死亡的时候。
英雄本色*：有信心不一定会成功，没信心一定不会成功。
笑傲江湖之东方不败*：有人就有恩怨，有恩怨就有江湖。人就是江湖，你怎么退出？
开往春天的地铁：我一直怀疑27岁是否还会有一见钟情的倾心。我不知道该说什么，我只是突然在那一刻很想念她。
情人：我以经老了，在人来人往的大厅，有一位老人他向我走来，他说我认识你，那时的你还很年轻，美丽，你的身边有许许多多的追求者，不过跟那时相比，我更喜欢现在你这经历了沧桑的容颜？
春光乍泄：一直以为我跟他不一样，原来寂寞的时候，所有的人都一样。
春光乍泻：每个成功男人的背后，都有一个女人。每个不成功男人的背后，都有两个。
好想好想谈恋爱：承诺是男人给女人的定心丸。吃了安心，虽然这定心丸的药性有待考证，但女人都希望吃了再说。
“如果，我多一张船票，你会不会跟我一起走？” 花样年华
往往都是事情改变人，人却改变不了事情。 无间道
我最讨厌你们这些打劫的了，一点技术含量都没有！！！！ 天下无贼
给我一个机会，我想做好人！ 无间道
做人如果没有梦想，那跟咸鱼有什么区别？ 少林足球

refs and see also

MathJax @

What is MathJax?

Open-source JS display engine
Modular, load components only when necessary
Rich API

Getting Started

Using the MathJax Content Delivery Network (CDN)
Add these to your src code (.html or .md)

<script type="text/javascript"
         src="http://cdn.mathjax.org/mathjax/latest/MathJax.js?config=TeX-AMS-MML_HTMLorMML">
</script>

MathJax hosted on GitHub: mathjax | MathJax
TeX and LaTeX input
- display: $$...$$ or \[...\]
- inline: $...$ (default) or $...$
MathML, etc.

Installing and Testing MathJax

Loading and Configuring MathJax

Common Configurations

Use default.js or use this request:

<script type="text/javascript"
         src="path-to-MathJax/MathJax.js?config=default">
</script>

Using MathJax in popular web platforms

MathJax TeX and LaTeX Support

Note that the TeX input processor implements only the math-mode macros of TeX and LaTeX, not the text-mode macros.

In Markdown, the back-tick (`) is used to mark verbatim text

And sometime you may double backslashs to escape

\\begin{array}{cc}
  a & b \\\\
  c & c
\\end{array}

You can use the \def, \newcommand, \renewcommand, \newenvironment, \renewenvironment, and \let commands to create your own macros and environments.

Some Examples I Tried

We'll define our own macros and use them, $$
   \def\RR{\bf R}
   \def\bold#1{\bf #1}
   \bold{``bold\ face"}$$
And do that again: \(\bold{``bold\ face"}\)
And do that again: $$\bold{``bold\ face"}$$
And do that again: $$\bold{``bold  face"}$$

And you could create a file in MathJax/config/local called local.js that contains your macro definitions:

MathJax.Hub.Config({
  TeX: {
    Macros: {
      RR: "{\\bf R}",
      bold: ["{\\bf #1}",1]
    }
  }
});

MathJax.Ajax.loadComplete("[MathJax]/config/local/local.js");

and then load it along with your main configuration file on the script that loads MathJax.js:

<script src="/MathJax/MathJax.js?config=TeX-AMS_HTML,local/local.js"></script>

Automatic Equation Numbering

<script type="text/x-mathjax-config">
MathJax.Hub.Config({
  TeX: { equationNumbers: { autoNumber: "AMS" } }
});
</script>

refs and see also

MathJax Document

AC – Axiom of Choice.
AL - Action limit.
Ai – Airy function.
Alt – alternating group (Alt(n) is also written as An.)
An. - alternate
Aut – automorphism group.
Bi – Airy function of the second kind.
Card – cardinality(基数) of a set. (Card(X) is also written #X, ♯X or |X|.)
Chi - hyperbolic cosine (chx) integral function. ch+i
Ci - cosine integral function.
Cl – topological closure.
DNE - a solution for an expression does not exist, or is undefined. Generally used with limits and integrals. Define None Equation or Does Not Exist
Ei – exponential integral function.
End – categories of endomorphisms.
Eqn – equation.
Ext – Ext functor.
FOL – first-order logic.
Frob – Frobenius endomorphism.
GF - Galois field.
GL – general linear group.
Gal – Galois group. (Also written as Γ.)
HOL – higher-order logic.
Hom – Hom functor.
Im – either image of a function or imaginary part of a complex number.
Ker – kernel.
LHS – left-hand side of an equation.
LST – language of set theory.
Li – offset logarithmic integral function.
NAND – not-and in logic, see Sheffer stroke
NOR – not-or in logic.
NTS – need to show.
No. – number.
PGL – projective general linear group.
PSL – projective special linear group.
Pr – probability of an event.
QED – “Quod erat demonstrandum”, a Latin phrase used at the end of a definitive proof. how to pronunce?
QEF – “quod erat faciendum”, a Latin phrase sometimes used at the end of a construction.
RHS – right-hand side of an equation.
RTP – required to prove.
RV – Random Variable. (or as R.V.)
Re – real part of a complex number. (Also written .)
Rk – rank.
SL – special linear group.
STP – it is sufficient to prove.
**Shi - hyperbolic sine integral function.
**Si - sine integral function.
Soln – solution.
Sp – linear span of a set of vectors. (Also written with angle brackets.)
Spec – spectrum of a ring.
Sym – symmetric group (Sym(n) is also written as Sn.)
TFAE – the following are equivalent.
Thm – theorem.
Tor – Tor functor.
Tr – trace, either the field trace, or the trace of a matrix or linear transformation.
WMA - we may assume.
WO – well-ordered set.
WTP – want to prove.
WTS – want to show.
W^5 – which was what we wanted. Synonym of Q.E.D.
XOR - exclusive or in logic.
ZF – Zermelo–Fraenkel axioms of set theory.
ZFC – Zermelo–Fraenkel axioms (with the Axiom of Choice) of set theory.
a.e. – almost everywhere
a.s. – almost surely
adj – adjugate of a matrix.
arccos – inverse cosine function.
arccosec – inverse cosecant function. (Also written as arccsc.)
arccot – inverse cotangent function.
arccsc – inverse cosecant function. (Also written as arccosec.)
arcosech – inverse hyperbolic cosecant function. (Also written as arcsch.)
arcosh – inverse hyperbolic cosine function.
arcoth – inverse hyperbolic cotangent function.
arcsch – inverse hyperbolic cosecant function. (Also written as arcosech.)
arcsec – inverse secant function.
arcsin – inverse sine function.
arctan – inverse tangent function.
arg max – argument of the maximum.
arg min – argument of the minimum.
arg – argument of a complex number.
arsech – inverse hyperbolic secant function.
arsinh – inverse hyperbolic sine function.
artanh – inverse hyperbolic tangent function.
cdf – cumulative distribution function.
char – characteristic
**cis - cos + i sin function.
cod – codomain. (Also written as codom.)
codom – codomain. (Also written as cod.)
cos – cosine function.
cosec – cosecant function. (Also written as csc.)
cosech – hyperbolic cosecant function. (Also written as csch.)
cosh – hyperbolic cosine function.
cot – cotangent function.
coth – hyperbolic cotangent function.
cov – covariance of a pair of random variables.
csc – cosecant function. (Also written as cosec.)
csch – hyperbolic cosecant function. (Also written as cosech.)
curl – curl of a vector field. (Also written as rot.)
deg – degree of a polynomial. (Also written as ∂.)
del – del, a differential operator. (Also written as （倒三角）).)
det – determinant of a matrix or linear transformation.
dim – dimension of a vector space.
div – divergence of a vector field.
dkl – decalitre（公斗；十升）deca + litre（就是我们常用的 1L 矿泉水）
dom – domain of a function. (Or, more generally, a relation.)
erf – error function
erfc – complementary error function.
exp – exponential function. (exp x is also written as ex.)
ext – exterior.
gcd – greatest common divisor of two numbers. (Also written as hcf.)
glb – greatest lower bound. (Also written as inf.)
grad – gradient of a scalar field.
hcf – highest common factor of two numbers. (Also written as gcd.)
iff – if and only if.
iid - independent and identically distributed random variables.
inf – infimum of a set. (Also written as glb.)
int – interior.
lcm – lowest common multiple of two numbers.
lerp – linear interpolation.
lg – common logarithm (log10) or binary logarithm (log2).
li – logarithmic integral function or linearly independent.
lim inf – limit inferior.
lim sup – limit superior.
lim – limit of a sequence, or of a function.
ln – natural logarithm, loge.
log – logarithm. (If without a subscript, this may mean either log10 or loge.)
logh – natural logarithm, loge.
lub – least upper bound. (Also written sup.)
max – maximum of a set.
min – minimum of a set.
mod – modulo.
mx – matrix.
ord – ordinal number of a well-ordered set.
pdf – probability density function.
pf – proof.
pmf – probability mass function.
ran – range of a function.
resp – respectively.
rng – non-unital ring.
rot – rotor of a vector field. (Also written as curl.)
sec – secant function.
sech – hyperbolic secant function.
seg – initial segment of.
sgn – signum function.
sin – sine function.
sinc – sinc function.
sinh – hyperbolic sine function.
st – such that or so that.
sup – supremum of a set. (Also written lub.)
supp – support of a function.
tan – tangent function.
tanh – hyperbolic tangent function.
undef - a function or expression is undefined
var – variance of a random variable.
walog – without any loss of generality.
wff – well-formed formula.
whp - with high probability.
wlog – without loss of generality.
wrt – with respect to or with regard to.

refs and see also

M3U @

M3U is a computer file format that contains multimedia playlists. It originally was designed for audio files, such as MP3, but various software now uses it to play video file lists. M3U’s can also point a media player to an online streaming audio source. Numerous media players and software applications supports the M3U file format.

Samples

Example 1

#EXTM3U

#EXTINF:123, Sample artist - Sample title
C:\Documents and Settings\I\My Music\Sample.mp3

#EXTINF:321,Example Artist - Example title
C:\Documents and Settings\I\My Music\Greatest Hits\Example.ogg

Example 2
```
C:\Music
```

Example 3

#EXTM3U

#EXTINF:123, Sample artist - Sample title

Example 4

Alternative\Band - Song.mp3
Classical\Other Band - New Song.mp3
Stuff.mp3
D:\More Music\Foo.mp3
..\Other Music\Bar.mp3
http://emp.cx:8000/Listen.pls
http://www.example.com/~user/Mine.mp3

Example 5

#EXTM3U
#EXTINF:233,Everclear - So Much For The Afterglow
Alternative\everclear_SMFTA.mp3
#EXTINF:227,Weird Al - Everything You Know Is Wrong
Comedy\Weird_Al_Everything_You_Know_Is_Wrong.mp3
#EXTINF:187,Weird Al Yankovic - This is the Life
Weird_Al_This_Is_The_Life.mp3
#EXTINF:129,Weird Al: Bad Hair Day - Gump
http://www.site.com/~user/gump.mp3
#EXTINF:-1,My Cool Stream
http://www.site.com:8000/listen.pls

#EXTM3U At the VERY top of the Extended M3U file is this header, which signifies this is an extended M3U file. #EXTM3U must be all capital letters.

#EXTINF:233,Everclear - So Much For The Afterglow

This is the line that tends to confuse people. Let’s break it up into parts

#EXTINF: This signifies this is an Extended Information field. It ends with a colorn.

233: This is the time of the file in seconds followed by a comma. (233 seconds = 3:53). On the last entry there is a negative one, this is usually seen on streams, it tells the program to ignore the time entry.

Everclear - So Much For The Afterglow: Title to display. This is usually the title read from the file name or ID3 tags. This also can be the name of a stream. No characters follow the title.

Alternative\everclear_SMFTA.mp3: File location as described above with basic playlists.

M3U8

M3U8 is a Unicode UTF-8 version of M3U files for support of Unicode/“international” characters/text. M3U8 follows the same principles as explained above.

Example

#EXTM3U

#EXT-X-STREAM-INF:PROGRAM-ID=1,BANDWIDTH=1217000,RESOLUTION=1280x720
2013girlwithipad-1200k.m3u8

#EXT-X-STREAM-INF:PROGRAM-ID=1,BANDWIDTH=824000,RESOLUTION=896x504
2013girlwithipad-800k.m3u8

#EXT-X-STREAM-INF:PROGRAM-ID=1,BANDWIDTH=629000,RESOLUTION=640x360
2013girlwithipad-600k.m3u8

#EXT-X-STREAM-INF:PROGRAM-ID=1,BANDWIDTH=430000,RESOLUTION=512x288
2013girlwithipad-400k.m3u8

#EXT-X-STREAM-INF:PROGRAM-ID=1,BANDWIDTH=216000,RESOLUTION=400x300
2013girlwithipad-200k.m3u8

#EXT-X-STREAM-INF:PROGRAM-ID=1,BANDWIDTH=121000,RESOLUTION=400x300
2013girlwithipad-110k.m3u8

refs and see also

Leonhard Euler @

Leonhard Euler

Leonhard Euler (/ˈɔɪlər/ oy-lər;) (15 April 1707 – 18 September 1783) was a pioneering Swiss mathematician and physicist. He made important discoveries in fields as diverse as infinitesimal calculus and graph theory. He also introduced much of the modern mathematical terminology and notation, particularly for mathematical analysis, such as the notion of a mathematical function. He is also renowned for his work in mechanics, fluid dynamics, optics, astronomy, and music theory.

无穷小量积分、图论，现代的数学命名和标记

Euler is considered to be the pre-eminent mathematician of the 18th century and one of the greatest mathematicians to have ever lived. He is also one of the most prolific mathematicians; his collected works fill 60– 80 quarto（四开） volumes. He spent most of his adult life in St. Petersburg, Russia, and in Berlin, Prussia.

A statement attributed to Pierre-Simon Laplace expresses Euler’s influence on mathematics: “Read Euler, read Euler, he is the master of us all.”

Karl Weierstrass @

Karl Weierstrass

Karl Theodor Wilhelm Weierstrass (German: Weierstraß; 31 October 1815 – 19 February 1897) was a German mathematician often cited as the “father of modern analysis”. Despite leaving university without a degree, he studied mathematics and trained as a teacher, eventually teaching mathematics, physics, botany and gymnastics.

Weierstrass formalized the definition of the continuity of a function, and used it and the concept of uniform convergence to prove the Bolzano– Weierstrass theorem and Heine–Borel theorem.

Joseph-Louis Lagrange @

Joseph-Louis Lagrange

Joseph-Louis Lagrange (/ləˈɡrɑːndʒ/ or /ləˈɡreɪndʒ/; French: [laˈgrɑ̃ʒ]), born Giuseppe Lodovico Lagrangia or Giuseppe Ludovico De la Grange Tournier (also reported as Giuseppe Luigi Lagrange or Lagrangia) (25 January 1736 – 10 April 1813), was an Italian Enlightenment Era mathematician and astronomer. He made significant contributions to the fields of analysis, number theory, and both classical and celestial mechanics.

In 1766, on the recommendation of Euler and d’Alembert, Lagrange succeeded Euler as the director of mathematics at the Prussian Academy of Sciences in Berlin, Prussia, where he stayed for over twenty years, producing volumes of work and winning several prizes of the French Academy of Sciences. Lagrange’s treatise on analytical mechanics (Mécanique analytique, 4. ed., 2 vols. Paris: Gauthier-Villars et fils, 1888–89), written in Berlin and first published in 1788, offered the most comprehensive treatment of classical mechanics since Newton and formed a basis for the development of mathematical physics in the nineteenth century.

In 1787, at age 51, he moved from Berlin to Paris and became a member of the French Academy. He remained in France until the end of his life. He was significantly involved in the decimalisation in Revolutionary France, became the first professor of analysis at the École Polytechnique upon its opening in 1794, founding member of the Bureau des Longitudes and Senator in 1799.

James Stirling @

Stirling’s grave in Greyfriars Kirkyard, Edinburgh, general view. It is the small plate between the two large tablets.

James Stirling (May 1692 Garden, Stirlingshire – 5 December 1770 Edinburgh) was a Scottish mathematician. The Stirling numbers, Stirling permutations, and Stirling’s approximation are named after him. He also proved the correctness of Isaac Newton’s classification of cubics.

Stirling was the third son of Archibald Stirling of Garden, Stirling of Keir (Lord Garden, a lord of session). At 18 years of age he went to Balliol College, Oxford, where, chiefly through the influence of the Earl of Mar, he was nominated (1711) one of Bishop Warner’s exhibitioners (or Snell exhibitioner) at Balliol. In 1715 he was expelled on account of his correspondence with members of the Keir and Garden families, who were noted Jacobites, and had been accessory to the “Gathering of the Brig o’ Turk” in 1708.

Joseph Fourier @

Jean-Baptiste Joseph Fourier

Jean-Baptiste Joseph Fourier (/ˈfʊəriˌeɪ, -iər/; French: [fuʁje]; 21 March 1768 – 16 May 1830) was a French mathematician and physicist born in Auxerre and best known for initiating the investigation of Fourier series and their applications to problems of heat transfer and vibrations. The Fourier transform and Fourier’s law are also named in his honour. Fourier is also generally credited with the discovery of the greenhouse effect.

There were three important contributions in this work, one purely mathematical, two essentially physical. In mathematics, Fourier claimed that any function of a variable, whether continuous or discontinuous, can be expanded in a series of sines of multiples of the variable. Though this result is not correct without additional conditions, Fourier’s observation that some discontinuous functions are the sum of infinite series was a breakthrough. The question of determining when a Fourier series converges has been fundamental for centuries. Joseph-Louis Lagrange had given particular cases of this (false) theorem, and had implied that the method was general, but he had not pursued the subject. Peter Gustav Lejeune Dirichlet was the first to give a satisfactory demonstration of it with some restrictive conditions. This work provides the foundation for what is today known as the Fourier transform.

One important physical contribution in the book was the concept of dimensional homogeneity in equations; i.e. an equation can be formally correct only if the dimensions match on either side of the equality; Fourier made important contributions to dimensional analysis. The other physical contribution was Fourier’s proposal of his partial differential equation for conductive diffusion of heat. This equation is now taught to every student of mathematical physics.

Henri Poincaré @

Henri Poincaré

Jules Henri Poincaré (French: [ʒyl ɑ̃ʁi pwɛ̃kaʁe]; 29 April 1854 – 17 July 1912) was a French mathematician, theoretical physicist, engineer, and a philosopher of science. He is often described as a polymath, and in mathematics as The Last Universalist by Eric Temple Bell, since he excelled in all fields of the discipline as it existed during his lifetime.

As a mathematician and physicist, he made many original fundamental contributions to pure and applied mathematics, mathematical physics, and celestial mechanics. He was responsible for formulating the Poincaré conjecture, which was one of the most famous unsolved problems in mathematics until it was solved in 2002–2003. In his research on the three-body problem, Poincaré became the first person to discover a chaotic deterministic system which laid the foundations of modern chaos theory. He is also considered to be one of the founders of the field of topology.

Poincaré made clear the importance of paying attention to the invariance of laws of physics under different transformations, and was the first to present the Lorentz transformations in their modern symmetrical form. Poincaré discovered the remaining relativistic velocity transformations and recorded them in a letter to Dutch physicist Hendrik Lorentz (1853–1928) in 1905. Thus he obtained perfect invariance of all of Maxwell’s equations, an important step in the formulation of the theory of special relativity.

The Poincaré group used in physics and mathematics was named after him.

Issac Newton @

Issac Newton

Sir Isaac Newton Kt, PRS (/ˈnjuːtən/; 25 December 1642 – 20 March 1726/27) was an English physicist and mathematician (described in his own day as a “natural philosopher”) who is widely recognised as one of the most influential scientists of all time and a key figure in the scientific revolution. His book Philosophiæ Naturalis Principia Mathematica (“Mathematical Principles of Natural Philosophy”), first published in 1687, laid the foundations for classical mechanics. Newton made seminal contributions to optics, and he shares credit with Gottfried Leibniz for the development of calculus.

Newton’s Principia formulated the laws of motion and universal gravitation, which dominated scientists’ view of the physical universe for the next three centuries. By deriving Kepler’s laws of planetary motion from his mathematical description of gravity, and then using the same principles to account for the trajectories of comets, the tides, the precession of the equinoxes, and other phenomena, Newton removed the last doubts about the validity of the heliocentric model of the Solar System. This work also demonstrated that the motion of objects on Earth and of celestial bodies could be described by the same principles. His prediction that Earth should be shaped as an oblate spheroid was later vindicated by the measurements of Maupertuis, La Condamine, and others, which helped convince most Continental European scientists of the superiority of Newtonian mechanics over the earlier system of Descartes.

Newton built the first practical reflecting telescope and developed a theory of colour based on the observation that a prism decomposes white light into the many colours of the visible spectrum. He formulated an empirical law of cooling, studied the speed of sound, and introduced the notion of a Newtonian fluid. In addition to his work on calculus, as a mathematician Newton contributed to the study of power series, generalised the binomial theorem to non-integer exponents, developed a method for approximating the roots of a function, and classified most of the cubic plane curves.

Newton was a fellow of Trinity College and the second Lucasian Professor of Mathematics at the University of Cambridge. He was a devout but unorthodox Christian and, unusually for a member of the Cambridge faculty of the day, he refused to take holy orders in the Church of England, perhaps because he privately rejected the doctrine of the Trinity. Beyond his work on the mathematical sciences, Newton dedicated much of his time to the study of biblical chronology and alchemy, but most of his work in those areas remained unpublished until long after his death. In his later life, Newton became president of the Royal Society. Newton served the British government as Warden and Master of the Royal Mint.

Henri Lebesgue @

Henri Lebesgue

Henri Léon Lebesgue (French: [ɑ̃ʁi leɔ̃ ləbɛɡ]; June 28, 1875 – July 26, 1941) was a French mathematician most famous for his theory of integration, which was a generalization of the 17th century concept of integration—summing the area between an axis and the curve of a function defined for that axis. His theory was published originally in his dissertation Intégrale, longueur, aire (“Integral, length, area”) at the University of Nancy during 1902.

Approximation of the Riemann integral by rectangular areas.

Lebesgue invented a new method of integration to solve this problem. Instead of using the areas of rectangles, which put the focus on the domain of the function, Lebesgue looked at the codomain of the function for his fundamental unit of area. Lebesgue’s idea was to first define measure, for both sets and functions on those sets. He then proceeded to build the integral for what he called simple functions; measurable functions that take only finitely many values. Then he defined it for more complicated functions as the least upper bound of all the integrals of simple functions smaller than the function in question.

Lebesgue integration has the property that every function defined over a bounded interval with a Riemann integral also has a Lebesgue integral, and for those functions the two integrals agree. Furthermore, every bounded function on a closed bounded interval has a Lebesgue integral and there are many functions with a Lebesgue integral that have no Riemann integral.

Method of Lebesgue’s integration.

As part of the development of Lebesgue integration, Lebesgue invented the concept of measure, which extends the idea of length from intervals to a very large class of sets, called measurable sets (so, more precisely, simple functions are functions that take a finite number of values, and each value is taken on a measurable set). Lebesgue’s technique for turning a measure into an integral generalises easily to many other situations, leading to the modern field of measure theory.

The Lebesgue integral is deficient in one respect. The Riemann integral generalises to the improper Riemann integral to measure functions whose domain of definition is not a closed interval. The Lebesgue integral integrates many of these functions (always reproducing the same answer when it did), but not all of them. For functions on the real line, the Henstock integral is an even more general notion of integral (based on Riemann’s theory rather than Lebesgue’s) that subsumes both Lebesgue integration and improper Riemann integration. However, the Henstock integral depends on specific ordering features of the real line and so does not generalise to allow integration in more general spaces (say, manifolds), while the Lebesgue integral extends to such spaces quite naturally.

Guillaume de l’Hôpital @

Guillaume de l’Hôpital

Guillaume François Antoine, Marquis de l’Hôpital (French: [ɡijom fʁɑ̃swa ɑ̃ twan maʁki də lopital]; 1661 – 2 February 1704) was a French mathematician. His name is firmly associated with l’Hôpital’s rule for calculating limits involving indeterminate forms 0/0 and ∞/∞. Although the rule did not originate with l’Hôpital, it appeared in print for the first time in his treatise on the infinitesimal calculus, entitled Analyse des Infiniment Petits pour l’Intelligence des Lignes Courbes. This book was a first systematic exposition of differential calculus. Several editions and translations to other languages were published and it became a model for subsequent treatments of calculus.

L’Hôpital was born into a military family. His father was Anne-Alexandre de l’Hôpital, a Lieutenant-General of the King’s army, Comte de Sainte-Mesme and the first squire of Gaston, Duke of Orléans. His mother was Elisabeth Gobelin, a daughter of Claude Gobelin, Intendant in the King’s Army and Councilor of the State.

L’Hôpital abandoned a military career due to poor eyesight and pursued his interest in mathematics, which was apparent since his childhood. For a while, he was a member of Nicolas Malebranche’s circle in Paris and it was there that in 1691 he met young Johann Bernoulli, who was visiting France and agreed to supplement his Paris talks on infinitesimal calculus with private lectures to l’Hôpital at his estate at Oucques. In 1693, l’Hôpital was elected to the French academy of sciences and even served twice as its vice-president. Among his accomplishments were the determination of the arc length of the logarithmic graph, one of the solutions to the brachistochrone problem, and the discovery of a turning point singularity on the involute of a plane curve near an inflection point.

L’Hôpital exchanged ideas with Pierre Varignon and corresponded with Gottfried Leibniz, Christiaan Huygens, and Jacob and Johann Bernoulli. His Traité analytique des sections coniques et de leur usage pour la résolution des équations dans les problêmes tant déterminés qu’indéterminés (“Analytic treatise on conic sections”) was published posthumously in Paris in 1707.

Gottfried Willhelm Leibniz @

leibniz-portrait

Gottfried Wilhelm (von) Leibniz (/ˈlaɪbnɪts/; German: [ˈɡɔtfʁiːt ˈvɪlhɛ lm fɔn ˈlaɪbnɪts] or [ˈlaɪpnɪts]; French: Godefroi Guillaume Leibnitz; July 1, 1646 – November 14, 1716) was **a German polymath and philosopher who occupies a prominent place in the history of mathematics and the history of philosophy. Scholars including Bertrand Russell believe Leibniz developed calculus independently of Isaac Newton, and Leibniz’s notation has been widely used ever since it was published. It was only in the 20th century that his Law of Continuity and Transcendental Law of Homogeneity found mathematical implementation (by means of non-standard analysis). He became one of the most prolific inventors in the field of mechanical calculators. While working on adding automatic multiplication and division to Pascal’s calculator, he was the first to describe a pinwheel calculator in 1685 and invented the Leibniz wheel, used in the arithmometer, the first mass-produced mechanical calculator. He also refined the binary number system, which is the foundation of virtually all digital computers.

In philosophy, Leibniz is most noted for his optimism, i.e. his conclusion that our Universe is, in a restricted sense, the best possible one that God could have created, an idea that was often lampooned by others such as Voltaire. Leibniz, along with René Descartes and Baruch Spinoza, was one of the three great 17th-century advocates of rationalism. The work of Leibniz anticipated modern logic and analytic philosophy, but his philosophy also looks back to the scholastic tradition, in which conclusions are produced by applying reason of first principles or prior definitions rather than to empirical evidence.

Leibniz made major contributions to physics and technology, and anticipated notions that surfaced much later in philosophy, probability theory, biology, medicine, geology, psychology, linguistics, and computer science. He wrote works on philosophy, politics, law, ethics, theology, history, and philology. Leibniz’s contributions to this vast array of subjects were scattered in various learned journals, in tens of thousands of letters, and in unpublished manuscripts. He wrote in several languages, but primarily in Latin, French, and German. There is no complete gathering of the writings of Leibniz.

Giuseppe Peano @

Giuseppe Peano

Giuseppe Peano (Italian: [dʒuˈzɛppe peˈaːno]; 27 August 1858 – 20 April 1932) was an Italian mathematician. The author of over 200 books and papers, he was a founder of mathematical logic and set theory, to which he contributed much notation. The standard axiomatization of the natural numbers is named the Peano axioms in his honor. As part of this effort, he made key contributions to the modern rigorous and systematic treatment of the method of mathematical induction. He spent most of his career teaching mathematics at the University of Turin.

After his mother died in 1910, Peano divided his time between teaching, working on texts aimed for secondary schooling including a dictionary of mathematics, and developing and promoting his and other auxiliary languages, becoming a revered member of the international auxiliary language movement. He used his membership of the Accademia dei Lincei to present papers written by friends and colleagues who were not members (the Accademia recorded and published all presented papers given in sessions).

During the years 1913–1918, Peano published several papers that dealt with the remainder term for various numerical quadrature formulas, and introduced the Peano kernel.

In 1925 Peano switched Chairs unofficially from Infinitesimal Calculus to Complementary Mathematics, a field which better suited his current style of mathematics. This move became official in 1931. Giuseppe Peano continued teaching at Turin University until the day before he died, when he suffered a fatal heart attack.

George Green @

The title page to Green’s original essay on what is now known as Green’s theorem.

George Green (14 July 1793 – 31 May 1841) was a British mathematical physicist who wrote An Essay on the Application of Mathematical Analysis to the Theories of Electricity and Magnetism (Green, 1828). The essay introduced several important concepts, among them a theorem similar to the modern Green’s theorem, the idea of potential functions as currently used in physics, and the concept of what are now called Green’s functions. Green was the first person to create a mathematical theory of electricity and magnetism and his theory formed the foundation for the work of other scientists such as James Clerk Maxwell, William Thomson, and others. His work on potential theory ran parallel to that of Carl Friedrich Gauss.

Green’s life story is remarkable in that he was almost entirely self-taught. He received only about one year of formal schooling as a child, between the ages of 8 and 9.

In his final years at Cambridge, Green became rather ill, and in 1840 he returned to Sneinton, only to die a year later. There are rumours that at Cambridge, Green had “succumbed to alcohol”, and some of his earlier supporters, such as Sir Edward Bromhead, tried to distance themselves from him.

Green’s work was not well known in the mathematical community during his lifetime. Besides Green himself, the first mathematician to quote his 1828 work was the Briton Robert Murphy (1806–1843) in his 1833 work. In 1845, four years after Green’s death, Green’s work was rediscovered by the young William Thomson (then aged 21), later known as Lord Kelvin, who popularised it for future mathematicians. According to the book “George Green” by D.M. Cannell, William Thomson noticed Murphy’s citation of Green’s 1828 essay but found it difficult to locate Green’s 1828 work; he finally got some copies of Green’s 1828 work from William Hopkins in 1845.

Gamma Function @

In mathematics, the gamma function (represented by the capital Greek letter Γ) is an extension of the factorial function, with its argument shifted down by 1, to real and complex numbers. That is, if n is a positive integer:

\[\Gamma(n) = (n-1)!.\]

The gamma function is defined for all complex numbers except the non-positive integers. For complex numbers with a positive real part, it is defined via a convergent improper integral:

\[\Gamma(t) = \int_0^\infty x^{t-1} e^{-x}\,dx.\]

This integral function is extended by analytic continuation to all complex numbers except the non-positive integers (where the function has simple poles), yielding the meromorphic function we call the gamma function. In fact the gamma function corresponds to the Mellin transform of the negative exponential function:

The gamma function is a component in various probability-distribution functions, and as such it is applicable in the fields of probability and statistics, as well as combinatorics.

Georg Cantor @

Georg Cantor

Georg Ferdinand Ludwig Philipp Cantor (/ˈkæntɔːr/ KAN-tor; German: [ˈɡeɔ ʁkˈfɛʁdinant ˈluːtvɪç ˈfɪlɪp ˈkantɔʁ]; March 3 [O.S. February 19] 1845 – January 6, 1918) was a German mathematician. He invented set theory, which has become a fundamental theory in mathematics. Cantor established the importance of one-to-one correspondence between the members of two sets, defined infinite and well-ordered sets, and proved that the real numbers are more numerous than the natural numbers. In fact, Cantor’s method of proof of this theorem implies the existence of an “infinity of infinities”. He defined the cardinal and ordinal numbers and their arithmetic. Cantor’s work is of great philosophical interest, a fact of which he was well aware.

Cantor’s theory of transfinite numbers was originally regarded as so counter-intuitive – even shocking – that it encountered resistance from mathematical contemporaries such as Leopold Kronecker and Henri Poincaré and later from Hermann Weyl and L. E. J. Brouwer, while Ludwig Wittgenstein raised philosophical objections. Cantor, a devout Lutheran, believed the theory had been communicated to him by God. Some Christian theologians (particularly neo-Scholastics) saw Cantor’s work as a challenge to the uniqueness of the absolute infinity in the nature of God – on one occasion equating the theory of transfinite numbers with pantheism – a proposition that Cantor vigorously rejected.

The objections to Cantor’s work were occasionally fierce: Henri Poincaré referred to his ideas as a “grave disease” infecting the discipline of mathematics, and Leopold Kronecker’s public opposition and personal attacks included describing Cantor as a “scientific charlatan”, a “renegade” and a “corrupter of youth.” Kronecker objected to Cantor’s proofs that the algebraic numbers are countable, and that the transcendental numbers are uncountable, results now included in a standard mathematics curriculum. Writing decades after Cantor’s death, Wittgenstein lamented that mathematics is “ridden through and through with the pernicious idioms of set theory,” which he dismissed as “utter nonsense” that is “laughable” and “wrong”. Cantor’s recurring bouts of depression from 1884 to the end of his life have been blamed on the hostile attitude of many of his contemporaries, though some have explained these episodes as probable manifestations of a bipolar disorder.

The harsh criticism has been matched by later accolades. In 1904, the Royal Society awarded Cantor its Sylvester Medal, the highest honor it can confer for work in mathematics. David Hilbert defended it from its critics by declaring: “No one shall expel us from the Paradise that Cantor has created.”

Donald Ervin Knuth @

Donald Ervin Knuth (/kəˈnuːθ/ kə-nooth; born January 10, 1938) is an American computer scientist, mathematician, and Professor Emeritus at Stanford University.

美国程序员、数学家、Stanford 大学教授

He is the author of the multi-volume work The Art of Computer Programming. Knuth has been called the “father” of the analysis of algorithms. He contributed to the development of the rigorous analysis of the computational complexity of algorithms and systematized formal mathematical techniques for it. In the process he also popularized the asymptotic notation. In addition to fundamental contributions in several branches of theoretical computer science, Knuth is the creator of the TeX computer typesetting system, the related METAFONT font definition language and rendering system, and the Computer Modern family of typefaces.

TAOCP（计算机程序艺术）的作者；算法分析之父；TeX、METAFONT 作者；

As a writer and scholar, Knuth created the WEB and CWEB computer programming systems designed to encourage and facilitate literate programming, and designed the MIX/MMIX instruction set architectures. As a member of the academic and scientific community, Knuth is strongly opposed to the policy of granting software patents. He has expressed his disagreement directly to both the United States Patent and Trademark Office and European Patent Organization.

文学性编程；反对软件专利；

Early life

winning a contest when he was in eighth grade by finding over 4,500 words that could be formed from the letters in “Ziegler’s Giant Bar”; the judges had only about 2,500 words on their master list.

Education

Physics or Music

1963 PhD in mathematics MIT

Early work

TAOCP

Writings

TAOCP TeX, METAFONT TAOCP Surreal Numbers 3:16 Bible Texts Illuminated

Health concerns

2006 prostate cancer pretty good

Computer musings

informal lectures at Stanford

Humor

pay a finder’s fee

Awards

Honors bestowed on Knuth include:

First ACM Grace Murray Hopper Award, 1971 Turing Award, 1974 Josiah Willard Gibbs Lecturer, 1978 National Medal of Science, 1979 Franklin Medal, 1988 John von Neumann Medal, 1995 Harvey Prize from the Technion, 1995 Kyoto Prize, 1996 Fellow of the Computer History Museum, 1998 Katayanagi Prize, 2010 BBVA Foundation Frontiers of Knowledge Award, 2010 Stanford University School of Engineering Hero Award, 2011

Homepage

F.A.Q.

关于退休

I retired early because I realized that I would need about 20 years of full-time work to complete The Art of Computer Programming (TAOCP), which I have always viewed as the most important project of my life.

邮件

1990 再不用邮箱

解释 e-mail -> email

最爱的编程语言

The CWEB System of Structured Documentation Literate Programming

出版的书

TAOCP
The TeXbook, The METAFONTbook, Computers & Typesetting
Concrete Mathematics

为什么不写支票了？

How do you pronounce your last name? Knuth (Ka-NOOTH)

关于中文名

Curriculum Vitæ

I may not be able to read your message until many months have gone by, because I’m working intensively on The Art of Computer Programming. However, I promise to reply in due time.

Programs to Read

段子等

Galileo Galilei @

galilei-portrait

Math Functions @

Function

Affine Function

Quadric Function

Continuous Function

Trignometric Function

Exponential

refs and see also

“Even Homer nods”，太过分了。。。

The Hacker’s Code @

“A hacker of the Old Code.”

Hackers come and go, but a great hack is forever.
Public goods belong to the public.
Software hoarding is evil. Software does the greatest good given to the greatest number.
Don’t be evil.
Sourceless software sucks.
People have rights. Organizations live on sufferance(容许).
Governments are organizations.
If it is wrong when citizens do it, it is wrong when governments do it.
Information wants to be free. Information deserves to be free.
Being legal doesn’t make it right.
Being illegal doesn’t make it wrong.
Subverting tyranny is the highest duty.
Trust your technolust!

The Hacker’s Code of Ethics

Levy (1984) suggests that there is a “code of ethics” for hacking which, though not pasted on the walls, is in the air:

Access to Computers - and anything which might teach you something about the way the world works - should be unlimited and total. Always yield to the Hands-On Imperative!
All information should be free.
Mistrust Authority - Promote Decentralization.
Hackers should be judged by their hacking, not bogus criteria such as degrees, age, race, or position.
You can create art and beauty on a computer.
Computers can change your life for the better.

DRAFT The Hacker’s Code DRAFT

Preamble: We, the people of the electronic universe, in order to establish a society of knowledge and skills, do hereby proclaim the following.

Hackers are diverse, from all cultures and backgrounds. Every hacker is unique, yet we all share some characteristics. While not every hacker follows this Code, many believe it is a fair description of our shared traditions, goals and values.
Hackers share and are willing to teach their knowledge
Hackers are skilled. Many are self-taught, or learn by interacting with other hackers.
Hackers seek knowledge. This knowledge may come from unauthorized or unusual sources, and is often hidden.
Hackers are tinkerers. They like to understand how things work, and want to make their own improvements or modifications.
Hackers often disagree with authority, including parents, employers, social customs and laws. They often seek to circumvent authority they disagree with.
Hackers disagree with each other. Different hackers have different values, and come from all backgrounds. This means that what one hacker is opposed to might be embraced by another.
Hackers are persistent, and are willing to devote hours, days and years to pursuing their individual passions.
This Code is not to prescribe how hackers act. Instead, it is to help us to recognize our own diversity and identify.
Every hacker must make his or her own decisions about what is right or wrong, and some might do things they believe are illegal, amoral or anti-social to achieve higher goals.
Hackers’ motivations are their own, and there is no reason for all hackers to agree.
Hackers have a shared identify, however, and many shared interests.
By reading this Code, hackers can recognize themselves and each other, and understand better the group they are a part of. This will be beneficial to all hackers.

The Conscience of a Hacker

                               ==Phrack Inc.==

                    Volume One, Issue 7, Phile 3 of 10

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
The following was written shortly after my arrest...

                       \/\The Conscience of a Hacker/\/

                                      by

                               +++The Mentor+++

                          Written on January 8, 1986
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=

        Another one got caught today, it's all over the papers.  "Teenager
Arrested in Computer Crime Scandal", "Hacker Arrested after Bank Tampering"...
        Damn kids.  They're all alike.

        But did you, in your three-piece psychology and 1950's technobrain,
ever take a look behind the eyes of the hacker?  Did you ever wonder what
made him tick, what forces shaped him, what may have molded him?
        I am a hacker, enter my world...
        Mine is a world that begins with school... I'm smarter than most of
the other kids, this crap they teach us bores me...
        Damn underachiever.  They're all alike.

        I'm in junior high or high school.  I've listened to teachers explain
for the fifteenth time how to reduce a fraction.  I understand it.  "No, Ms.
Smith, I didn't show my work.  I did it in my head..."
        Damn kid.  Probably copied it.  They're all alike.

        I made a discovery today.  I found a computer.  Wait a second, this is
cool.  It does what I want it to.  If it makes a mistake, it's because I
screwed it up.  Not because it doesn't like me...
                Or feels threatened by me...
                Or thinks I'm a smart ass...
                Or doesn't like teaching and shouldn't be here...
        Damn kid.  All he does is play games.  They're all alike.

        And then it happened... a door opened to a world... rushing through
the phone line like heroin through an addict's veins, an electronic pulse is
sent out, a refuge from the day-to-day incompetencies is sought... a board is
found.
        "This is it... this is where I belong..."
        I know everyone here... even if I've never met them, never talked to
them, may never hear from them again... I know you all...
        Damn kid.  Tying up the phone line again.  They're all alike...

        You bet your ass we're all alike... we've been spoon-fed baby food at
school when we hungered for steak... the bits of meat that you did let slip
through were pre-chewed and tasteless.  We've been dominated by sadists, or
ignored by the apathetic.  The few that had something to teach found us will-
ing pupils, but those few are like drops of water in the desert.

        This is our world now... the world of the electron and the switch, the
beauty of the baud.  We make use of a service already existing without paying
for what could be dirt-cheap if it wasn't run by profiteering gluttons, and
you call us criminals.  We explore... and you call us criminals.  We seek
after knowledge... and you call us criminals.  We exist without skin color,
without nationality, without religious bias... and you call us criminals.
You build atomic bombs, you wage wars, you murder, cheat, and lie to us
and try to make us believe it's for our own good, yet we're the criminals.

        Yes, I am a criminal.  My crime is that of curiosity.  My crime is
that of judging people by what they say and think, not what they look like.
My crime is that of outsmarting you, something that you will never forgive me
for.

        I am a hacker, and this is my manifesto.  You may stop this individual,
but you can't stop us all... after all, we're all alike.

                               +++The Mentor+++
_______________________________________________________________________________

refs and see also

Math Abbrev @

公理，定理
函数，幂函数，指数函数（和对数函数），三角函数==> e^x
Group，Field，Ring

数学符号

a, b, c, d, e, f, g, h
i, j, k
m, n
p, q, r, s, t
u, v, w
x, y, z
omega, episilon
pi, tau, etc

大哥大嫂过年好 @

大哥大嫂过年好，大哥大嫂过年好，大哥大嫂过年好

抱歉用姜文的鬼子来了开个恶趣味的玩笑

本小站是成人英语学习研究基地，站长呢，没啥本事，在一家所谓外企工作，大学时候参加过 CCTV 杯，对英文教学试验特别感兴趣，因为工作关系大姨妈经常犯，所以就在线做些感兴趣的事情减减压

本小站目标：以最科学高效的语言学理论和最牛叉有趣的学习材料作支撑，加上你自己的一点小坚持——每天 1-2 小时，依个人基础不同，1-2 年后人人都可习得英文，美剧电影随便看，口语流利自然说，原版教材小说随便读

很有趣是么？很不幸，先自问下一天 1-2 时，一年时间不动摇你能做到么？哈哈哈

在进入正文之前，先做个自测

1，在此前有没有照着录音一句话一句话暂停反复模仿的经历，如果有，请问每天一小时，最长坚持过多久，有没有超过三周？2，在此前有没有坚持做听写的经历，如果有，每天一小时，请问有没有坚持超过两周？3，你觉得自己看到不认识的单词的音标能做到比较标准的读出来么？4，估算下自己听英语的输入量大概有多少个小时，是否曾经每天坚持听 1-2 个小时的英文（随便什么，新闻，有声书之类，但中文字幕或中英字幕的美剧不算）5，请问你丢弃英文，从未接触，低于三年么？6，请问你高考英语及格了么？7，请问过去时，现在时，完成时，虚拟语气，副词性从句，名词性从句，形容词性从句这些基本语法概念有么？不要求精通，但是请问你知道么？8，请问你能听懂多快速度的英文？VOA 慢速那种？还是 VOA 慢速已经可以听懂但是常速仍然力不从心的？或者你根本就不知道 VOA 是什么，而且从来就没有过听英文的习惯？

如果以上问题，你给出的否定答案超过 3 个问题，那么下面正文并不适合你，你看完也不会有任何直接收获，请点开右边零基础那个房间，寻求赖世雄老师的帮助，每天一课，一年后学完全套教材，英文自然大成！

好，正文！

由于直接决定英文水平的其实就是听力，没错，这是一切英文能力基础中的基础，我相信二语教学中从听力入手的假说—婴幼儿接触语言，无一不是从声音入手，然后认字，学阅读和写作的，so，我在教程初期决定：所有级别的划定，统统只以听力材料的难度来划分，所以大声哭诉不知道自己英文级别的人，把我推荐的材料听下，觉得能听懂 70% 的，说明你就适合这个级别，如果全都能听懂但是英文仍然很烂的（我暂时先不计较你是不是在撒谎和跟我瞎操蛋），那么提高写要求，看自己能复述出多少，复述率 70% 左右的，甭管你听懂 100% 还是 120%，都只当作符合这个水平

最后废话句，虽然对本教程对号入座全部学完（不一定要从初始级别开始），应付任何考试都无问题，但是它本质上不针对考试，我只是在做英文习得的试验而已，再有人发帖发邮，说自己四六级 / 考研 / 口译 / 托福等垃圾考试要到了，所以进组要好好努力，或者求各种考试办法（比如托福雅思口语），我送你几个字：滚你妈逼的！

如果你说自己要晋升，或者要去外企，或者赚大钱，或者要移民出国做假洋鬼子，或者装逼说要看懂各类原版书做文艺青年，或者志向高洁说要使用英文多读专业书，学好本专业高精尖技术，出国留学做科学家报效祖国，那么小组对各位无任欢迎！赚到钱了也请记得请我吃饭

OK，先简单扫盲下

国外的 ESL 教学早就已经上升到心理学和脑神经学的高度了，各类语言学实验室开的兴旺，成果大批量产出，无数语言学家前赴后继殚精竭虑穷极一生，只为了追求拿最高效和最科学的教学手段方法，跟国内某机构或某名师拍脑袋想出来的办法（背熟新概念，背熟 2W 单词之类的言论）截然不同（庆父不死鲁难不已啊），其中的开宗立派的祖师爷，惹无数屌丝嫉妒，无数伪君子打压，国内无数英语系砖家叫兽故意掩盖伪装，被国人一只挡在门外的顶尖儿人物，就是南加州大学的 Dr Krashen！

技插：南加州的语言学专家怎么这么多，祖师爷是那的，我一外教是那毕业的，下文中要提到的 Jeff 也是哪的，真是风水宝地出人才啊

Dr Krashen 提出了几条著名的外语习得假说，根据我们今天的网络丰富资源，我们完全可以按照这几条假说来全面最大化的优化自己的学习，简单介绍下

1，输入 input 假说：绝大部分人的英文不好并不是因为他们 practice 的不够多，而是因为 input 不够，换言之没事喜欢瞎找老外搭讪无疑是个蠢办法，至于那种认为去国外了英文自然就会好，或者美国卖菜的英文都比我们好的多人的人都是傻逼，当然，这只是条假说，目前并无法证据其为完全真理，所以只能假定这些人是傻逼 2，i+1 理论：也叫做可理解性输入假说，在你认同输入假说的基础上，进行输入练习时，要遵守 i+1 的原则，i 即你现在的水平，1 即稍微高一点点的水平，这点被很多人熟悉，但是大家容易忽略的就是，在学习了一段时间后，水平提高了，以前的 i+1 其实已经是你现在 i 水准了，这个时候一定要 push 自己，去主动开拓，寻求进一步的提升，主动给自己的学习难度升级，这个是很少有人会做的

这条可理解性输入假说是最重要，也是最核心的 ESL 教学理论，跟其它语言学派不同，这个还靠谱点，事实上，有一种自然学习学派的观点，起码我是绝对不赞同的：一开始就应该拿常速英文来练习，好像刚出生的小孩一样，静心打坐聆听，就算听不懂也听下去，总有一天会顿悟，突然打通耳朵。就好像打通了任督二脉一样，你的英文的小宇宙就可以爆发，因为没有特别多的人试验过这种自然学习法，而且我相信绝大部分人不会有胆量拿自己的时间来试验这种办法，所以老老实实思索自己的级别，找一些略难的材料好好学一学，学好了，再升个级别，这样有阶段性的上升和提高，收获的是扎扎实实的进步和提高 3， Narrow input 假说，意思就是，输入的材料在一定时间内相对要狭窄些，但是这条假说却是小组里无一人会愿意遵守的，比如今晚还有人问我入门级别的语法相关，求推荐简单的原版书（入门语法想读原版书，这个太高级了些）。我的观点很明确，既然确定了自己的级别，那么就在一定时间内，只接触这个级别的材料，起码在学完前，尽量不要接触其它材料，分散注意力。不要订出那种手捧赖世雄，脚填 Cloze，眼读原版书之类的天才计划，就算你订了，按照小组的时间设定，我很怀疑你每天都有那么多时间能每个方面都 cover 到，订这种不切实际的计划没什么意思，更何况，一天数课的赖世雄老师已经占了你很大时间，再去读原版书既不靠谱，也不实际，我也很怀疑，作为一个需要赖世雄老师帮忙的小白，能看得懂 Peter Pan 么？

4，情绪机制学习的材料和环境应该是有趣的，轻松自如的，才能实现效果的最大化

以上，是我个人比较赞同的 Krashen 的理论，具体的，可自己谷歌，或参照我之前写的帖子：为什么一定要听 ESLPOD 和 Egnlishpod

So，根据这几条假说，我估摸着把国内目前已经有了一些基础的学习者分成三个级别，这个级别划分很简单，就是按照 1，听力能力；2，词汇能力来划分的 3，语法能力来划分

中级：能够听懂慢速英语，但是对慢速英语都要求认真听仔细听，还不能随心所欲的人，词汇量在 3-4K 左右

高级：轻松看懂无字幕美剧，原版专业书籍流畅读，词汇量 1W 以上，主动词汇超过 3K，各种英文从句和主句的造句方法都熟练使用，流畅阅读时代和经济学人等国际性报刊无障碍，与人交流或写作时，可以准确的使用单词和句式来表达自己的思想，语言文字不会地道，但一定会准确，清楚，易懂，口语表达会有自己个人口音，但比较流利

我相信 stuck 在中级水平的人多——毕竟这个级别努努力就上来了，但达到高级水平的人却少，且中级水平的人想达到高级，只觉得路漫漫其修远兮，道阻且长啊，穷此生未必能达到，不知道如何规划学习时长，监控学习效果

所以中级和高级之间肯定有个阶层，在这个阶层修炼的如鱼得水之后，闯下一关的高级就属于跳一跳，肯定摸得着的那种了

中高级：词汇在 4K—6K 左右，好一点背单词勤快的大概能达到 7K-8K，可以很轻松的听懂 VOA 慢速，但是在听常速英文的时候觉得困难重重，听懂率可能在 60%-70% 左右，看原版书觉得处处掣肘到处有生词不认识，在说和写方面，可以较为流畅的写，也可以表达，但是离轻松自如，并且写出来就知道对错的程度自己觉得很远，且困难重重，看不到什么提高的希望

国内普遍学习者的水平（通过最上面自测的学习者），大抵可以分成这三个级别——废话一句，平时没有输入习惯也就是听和读的习惯的人，自然是无法知道自己级别的，如果你看到这里还是不清楚自己级别，我只能 give up on you 了，请立刻 X 了此页转零基础帖

这种学习的巨大断层是国内基础教育和江湖派培训双重疏忽导致

国内基础教育就是大家熟悉的语法 - 翻译 - 背诵法，尤其是对词汇的背诵，懂语法背词汇多的人基本上都能通过考试——但这样对确实英文的输入并无多少增长，考试自然也检测不了什么水平——连听力题都是靠连蒙带猜，选择题和阅读题也多是靠所谓语感，这样一路蒙 + 猜过了四六八级，只能说明你运气好——发音，because 肯定发成 becaurse,famous 也是 famours，r 音到处飞，w 和 h 这两个字母一读就错；语法，各种名词性从句和形容词性从句以及副词性从句的构成规则一片糊涂，浑浑噩噩，简化从句更是掌握的一塌糊涂，更不知道怎么写好各种复合句了；阅读，因为从句知识一片糊涂，稍微长一点的句子满目抓瞎，压根不知道什么意思，连一开始的句子都读不懂，之后更不可能加快阅读速度了，自豪的做阅读题的高正确率无非是在大量做题之后依靠题目本身的简化句子连蒙带猜而已，基本的行文逻辑思维全无，更别提欣赏英美文学文字的艺术美感了。连这三项最简单的部分大家都做的极差，那么我们也不用和口语和写作表达了吧。。。辞不达意还在其次，对英文的 instant reflection 完全没有

（请问诸君感到膝盖中满箭木有？）

有些专家说国人对语法掌握很好，大家一说到学英文也常说自己的词汇好，书面英文好，阅读没问题，知识口语烂了些

但很不幸，在我看来，大部分人的英文，包括高分学习者都是狗屁不通，语法更烂——基本的造句知识大部分人掌握的都很差，选择题都是靠语感，和专家所说完全相反——用屁股想也知道了，如果大家的语法真的想你们所说的那么好，不会有那么多人抱怨英文难了，语法乃是英文根本中的根本，只要通了，以后不会很难

所以基础教育全面崩溃，一片苍凉，虽然自称语法 - 翻译法，但是连语法教授这一最基本的教学任务全部失败——大部分狗屁老师自己语法都未通。一言蔽之，失败！

而真正个人学习的时候，网络时代来临前资料缺乏有限，我们当时多是用广播收听 VOA 和 BBC，钟道隆老师的理论出来了之后总算是有了很好的学习方法，当时各种英文学习杂志本质上和这些广播没有什么不同，学习效果固然不错，但是在学习上有着一个巨大的断层。 VOA specail 每分钟只有 80 个词，词汇量在 3K 左右，常用的只有 1.5K，而 VOA 常速每分钟至少有 140 个词，词汇量高达 9K。从 80 个词到 140 个词的听力速度可以说是个彻底飞跃，词汇量也有个巨大鸿沟，英文学习的难度巨大分层——明显完全违背了 Dr Krashen 的 i+1 理论，所以很多人听 VOA 慢速听的开头一切良好，但是很多因为适应不了常速而放弃——这种时候就不是毅力和坚持的问题了，个人认为纯粹是方法和材料选择的问题了。。。

所以你看，学习是件痛苦的事情，尤其是你过了四六级一看美剧一读原版书还是满眼抓瞎的时候，哈哈哈（我们这里还没有讲复杂的英文造句呢）

纵观整个学习流派，没有任何一家提出过一个很好的系统的流程，让你从初级学到高级，尤其是在难度极大的中高级阶段的学习——大量泛听输入和连读弱读的讲解造句方法之类过渡阶段必须学习的东西也完全没人提及过——甚至连这个概念都从未有人提起过

是因为众多人的英文永远 stuck 在初级所以没人有中高级学习的体验吗？是侥幸顺利过渡完毕的高级学习者不屑来教人怎么过渡吗？但国内机构集体选择眼盲耳盲这一事实不能让人觉得不吊诡

如果没有人愿意或者不屑，那么让我来！我愿意来讲授自己当年好不容易突破的艰难困苦！我愿意来分享突破的最高效办法！我愿意撕下各种名师传奇的假面具！让我来踢爆国内各类跳梁小丑！

就好像洛杉矶的把妹界，众人都是无脑而跟风的，看到一种办法有效就纷纷效仿，讲故事有用就到处给妹子讲故事，幽默有用就到处到酒吧给妹子讲笑话——结果发现有的办法有用，有的办法只能被妹子扇耳光，为什么呢？没有任何一个人有好对策，一直到一位奇才——迷男的出现

迷男彻底扫清了把妹学上的流俗，肃清了那种一招鲜吃遍天的荒谬状况，革命性的指出，跟妹子交往是分成不同阶段的，搭讪认识是一个，约会是一个，约人家到你家里玩是一个，最后成功上垒把妹得手又是一个（好比英文的高级水平），每个阶段，都必须用不同的方法才能最和妹子的心思，尤其还要思考和认清自己和妹子的关系所处阶段，结合了当代女性心理学与 NLP 理论，大量实践，总结经验，开班授课，成功案例众多，随后出版书籍，众拙男花 25 人民币加上一颗不要脸的心反复练习，此生便可永远左拥右抱，常有温香软玉漂亮妹子在怀，社会从此稳定，造福于民，伟大！

你们可以想象下威尔斯密斯在 Hitch 全民情圣中的角色，虽然迷男大师跟这种角色有很大不同，你们有空自己去优酷看看他的教程便知道了

奶爸不才，但我自愿做英文学习界的迷男，设定系统，指出不同阶段的不同战略，教你认清自己，并仔细思考，时刻监控，你们身边的英文高手很多，一说学英文，每个人的方法可能都不同，什么跟读模仿，看美剧，听 BBC，看原版书，背词典也好，背课文也好，大家就会觉得每个人学习方法不同，要靠自己去琢磨，要找适合自己的，殊不知，这种所谓最适合自己的，往往背后的意思就是固步自封，真正的原因还是一个，不同阶段要做的事情是不一样的，看自己的水平选择相应的材料。这样大家都能学好英文，以后去英语角，男生可以靠一口流利英语泡到心仪女生，搞死洋垃圾和死老外，女生可以傍上老美改变国籍，从此一生不愁

而且随着网络时代的到来和数码技术的进步，过渡阶段的问题已经完美解决了，想知道？请在中级和中高阶段的帖子好好阅读吧!

etymology of mathematical terms @

引用 Joseph J. Rotman 的 The First Course in Abstract Algebra with Applications：

Giving the etymology of mathematical terms is rarely done. Let me explain, with an analogy, why I have included derivations of many terms.

There are many variations of standard poker games and, in my poker group, the dealer announces the game of his choice by naming it. Now some names are better than others. For example, “Little Red” is a game in which one’s smallest red card is wild; this is a good name because it reminds the players of its distinctive feature. On the other hand, “Aggravation” is not such a good name, for thought it is, indeed, suggestive, the name does not distinguish this particular game from several others.

Most terms in mathematics have been well chosen; there are more red names than aggravating ones. An example of a good name is even permutation, for a permutation is even if it is a product of an even number of transpositions. Another example of a good term is the parallelogram law describing vector addition. But many good names, clear when they were chosen, are now obscure because their roots are either in another language or in another discipline. The trigonometric terms tangent and secant are good names for those knowing some Latin, but they are obscure otherwise.

The term mathematics is obscure only because most of us do not know that it comes from the classical Greek word meaning “to learn”. The term corollary is doubly obscure; it comes from the Latin word meaning “flower”, but why should some theorems be called flowers? A plausible explanation is that it was common, in ancient Rome, to give flowers as gifts, and so a corollary is a gift bequeathed by a theorem. The term theorem comes from the Greek word meaning “to watch” or “to contemplate” (theatre has the same root); it was used by Euclid with its present meaning. The term lemma comes from the Greek word meaning “taken” or “received”; it is a statement that is taken for granted (for it has already been proved) in the course of proving a theorem. I believe that etymology of terms is worthwhile (and interesting!), for it often aids understanding by removing unnecessary obscurity.

英文	中文	溯源
Mathematics	数学	From Greek, “to learn”
Corollary	?	From Latin, “flower”, 花当时是一种礼物。类似现在文中常用的 Bonus
Theorem	定理	From Greek, “to watch”, “to contemplate”
Z, Q, R, C	?	- Zahl(German) meanning “number” - Rational Numbers; - Real Numbers; - Complex Numbers
Lemma	?	From Greek, “taken”, “received”, a.k.a. taken for granted
Induction	归纳法，演绎法	From Latin, “to lead”, came to mean “prevailing to do something” or “influencing”
Factor	?	From Latin, “to make”, or “to contribute”
Binomial	?	bi(Latin, “two”) + nomen(Latin, “name”, “term”); trinomial, monomial
Polynomial	?	poly(Greek, many) + namen(Latin, “name”, “term”)
Cyclotomic	?	From Greek, “circle splitting”
Algorithm	?	来自一个印度数学家 Khwarizmi
Googol	?	10^100
Leap Year	?	闰年的 2 月比平年的多一天，因为在 Roman calender 里三月一号才是一年的第一天
Calendar	?	From Greek, “to call”, evolved into the Latin for the first day of a month(when accounts were due)
Signum Matrix	? ?	From Latin, “mark”, or “token”, now we use “sign” Derived from the word meaning “mother”, means “womb” in Latin. More generally, it means something that contains the essence of a thing.
Translation	?	From Latin, “to transfer”. Language to language, point(of thoughts) to point.
Dihedron	?	di(Latin, “two”) + hedron(Greek, “two dimensional side”)
Stochastic	?	From Greek, “to guess”
Homomorphism	?	homo(Greek, “same”) + morphism(Greek, “shape” or “form”)
Isomorphism	?	iso(Greek, “equal”) + morphism(Greek, “shape” or “form”)
Kernel	?	From German, “grain” or “seed”. Indicating an important ingredient of a homomorphism
quaternion	?	?
Group, Ring	?	First used by E. H. Moore in 1893
Field	?	Krper(German), a “realm”, a “body” of things, or “collections of things”
Ring	?	Corps(French), a “realm”, a “body” of things, or “collections of things”
Domain	?	Abbrev. of integral domain of the German word *Integrettsbereich; A collection of things
Quadratic	?	From Latin, “four”. Four-sided figures(Like a square, with area x^2). Linear, quadratic, cubic.
Vector	?	From Latin, “to carry”, vectors in euclidean space carry the data of length and direction.
Scalar	?	From scale, which is from the Latin word meaning “ladder”, 因为梯子的横均匀（可以作为度量）
Orthogonal	?	ortho(Greek, “right”) + gon(Greek, “angle”); Right angled or perpendicular
Echelon	?	“Wings”; A matrix in echelon form（矩阵的梯形形式）
Eigenvalue	?	From Eigenwert(German). Wert means value, Eigen is characteristic or proper
Automorphism	?	auto(Greek, “self”) + morphism(“shape” or “form”)
Variety	?	Arose as a translation by E. Beltami(inspired by Gauss) of the German term Mannigfaltigkeit used by Riemann; nowdays, this term is usually tranlated as manifold
Sine	?	参考 [Sine 的故事] ( url here )
Root	?	参考 [Root 的故事] (url here)
Tangent	?	The Latin word tangere means “to touch”; a tangent is a line which touches the circle in only one point
Secant	?	The Latin word secare means “to cut”; a secant is a line that cuts a circle
Modulo	?	From Latin, “measure”

Letter	Letter Name	Pronunciation
A a	a	/ˈeɪ/
B b	bee	/ˈbiː/
C c	cee	/ˈsiː/
D d	dee	/ˈdiː/
E e	e	/ˈiː/
F f	ef	/ˈɛf/
G g	gee	/ˈdʒiː/
H h	aitch	/ˈeɪtʃ/
- -	haitch	/ˈheɪtʃ/
- -	hetch	/ˈhetʃ/
I i	i	/ˈaɪ/
J j	jay	/ˈdʒeɪ/
- -	jy	/ˈdʒaɪ/
K k	kay	/ˈkeɪ/
L l	el or ell	/ˈɛl/, /ˈɛɫ/
M m	em	/ˈɛm/
N n	en	/ˈɛn/
O o	o	/ˈəʊ/
P p	pee	/ˈpiː/
Q q	cue	/ˈkjuː/
R r	ar	/ˈɑː/
S s	ess	/ˈɛs/
T t	tee	/ˈtiː/
U u	u	/ˈjuː/
V v	vee	/ˈviː/
W w	double-u	/ˈdʌbəl.juː/
X x	ex	/ˈɛks/
Y y	wy or wye	/ˈwaɪ/
Z z	zed	/ˈzɛd/
- -	zee	/ˈziː/
- -	izzard	/ˈɪzərd/

Letter	Name	In LaTeX	Transliteration	Pronunciation
A α	alpha	-	a	AL-fuh
B β	beta	-	b	BAY-tuh, BEE-tuh
Γ γ	gamma		g	GAM-uh
Δ δ	delta		d	DELL-tuh
E ϵ ε	epsilon	-	e	EP-suh-lon
F ϝ ϛ	digamma	-	f	dee-GAM-uh ?
Z ζ	zeta	-	z	ZAY-tuh
H η	eta		ē	AY-tuh
Θ θ ϑ	theta		th	THAY-tuh, THEE-tuh
Ι ι	iota	-	i	eye-OH-tuh
K κ ϰ	kappa	-	k	CAY-uh
Λ λ	lambda		l	LAM-duh
M μ	mu	-	m	MYOO, MOO
N ν	nu	-	n	NOO, NYOO
Ξ ξ	xi		x	ZIGH, SIGN, KSEE
Ο ο	omicron	-	o	AH-mih-cron, OH-mih-cron
Π π ϖ	pi		p	PIE
Ρ ρ ϱ	rho	-	r / rh	ROE
Σ σ ς	sigma		s	SIG-muh
T τ	tau	-	t	TOW, TAW
Υ υ	upsilon		u	UP-suh-lon, YOOP-suh-lon
Φ ϕ φ	phi		phi	FIE, FEE
Χ χ	chi		ch	KIGN, KEE
Ψ ψ	psi		ps	SIGH, PSIGH, PSEE
Ω ω	omega		ō	oh-MEG-uh, oh-MEE-guh, oh-MAY-guh