slam十四講--習題一
習題1 Ax=b， 已知A，b要如何解x？
若A可逆，rank(A)=rank(A,b)=n. x=A^-1 * b 即A滿秩（/ 非奇異 / det(A)不等於0），可以解出x的唯一解
若rank(A)<rank(A,b) x無解。
若rank(A)=rank(A,b)<n, x多解。
習題2 高斯分佈
正態分佈（Normal distribution）又名高斯分佈（Gaussian distribution），是一個在數學、物理及工程等領域都非常重要的概率分佈，在統計學的許多方面有着重大的影響力。
若隨機變量X服從一個數學期望爲μ、標準方差爲σ2的高斯分佈，記爲：
X∼N(μ,σ2),
則其概率密度函數爲
代表在均值爲 
可見，高斯分佈的概率密度計算核心在於計算數據點到中心的距離，並且除以標準差將這個絕對距離轉化爲相對距離，然後通過距離平方的指數衰減計算概率密度。
它的高維形式：
習題3
c++ 類： http://www.cnblogs.com/mr-wid/archive/2013/02/18/2916309.html
STL ： http://www.runoob.com/cplusplus/cpp-stl-tutorial.html
習題7
Linuc目錄結構： http://www.cnblogs.com/JCSU/articles/2770249.html
習題9 vim的使用：
------------------------------
Lesson 1 SUMMARY
1. The cursor is moved using either the arrow keys or the hjkl keys.
h (left) j (down) k (up) l (right)
2. To start Vim from the shell prompt type: vim FILENAME <ENTER>
3. To exit Vim type: <ESC> :q! <ENTER> to trash all changes.
OR type: <ESC> :wq <ENTER> to save the changes.
4. To delete the character at the cursor type: x
5. To insert or append text type:
i type inserted text <ESC> insert before the cursor
A type appended text <ESC> append after the line
NOTE: Pressing <ESC> will place you in Normal mode or will cancel
an unwanted and partially completed command
-------------------------------
Lesson 2 SUMMARY
1. To delete from the cursor up to the next word type: dw
2. To delete from the cursor to the end of a line type: d$
3. To delete a whole line type: dd
4. To repeat a motion prepend it with a number: 2w
5. The format for a change command is:
operator [number] motion
where:
operator - is what to do, such as d for delete
[number] - is an optional count to repeat the motion
motion - moves over the text to operate on, such as w (word),
$ (to the end of line), etc.
6. To move to the start of the line use a zero: 0
7. To undo previous actions, type: u (lowercase u)
To undo all the changes on a line, type: U (capital U)
To undo the undo's, type: CTRL-R
--------------------------------
Lesson 3 SUMMARY
1. To put back text that has just been deleted, type p . This puts the deleted text AFTER the cursor (if a line was deleted it will go on the line below the cursor).
2. To replace the character under the cursor, type r and then the character you want to have there.
3. The change operator allows you to change from the cursor to where the motion takes you.
eg. Type ce to change from the cursor to the end of the word,
c$ to change to the end of a line.
4. The format for change is:
c [number] motion
---------------------------------------------
Lesson 4 SUMMARY
1. CTRL-G displays your location in the file and the file status.
G moves to the end of the file.
number G moves to that line number.
gg moves to the first line.
2. Typing / followed by a phrase searches FORWARD for the phrase.
Typing ? followed by a phrase searches BACKWARD for the phrase.
After a search type n to find the next occurrence in the same direction
or N to search in the opposite direction.
CTRL-O takes you back to older positions, CTRL-I to newer positions.
3. Typing % while the cursor is on a (,),[,],{, or } goes to its match.
4. To substitute new for the first old in a line type :s/old/new
To substitute new for all 'old's on a line type :s/old/new/g
To substitute phrases between two line #'s type :#,#s/old/new/g
To substitute all occurrences in the file type :%s/old/new/g
To ask for confirmation each time add 'c' :%s/old/new/gc
----------------
Lesson 5 SUMMARY
1. :!command executes an external command.
Some useful examples are:
(MS-DOS) (Unix)
:!dir :!ls - shows a directory listing.
:!del FILENAME :!rm FILENAME - removes file FILENAME.
2. :w FILENAME writes the current Vim file to disk with name FILENAME.
3. v motion :w FILENAME saves the Visually selected lines in file FILENAME.
4. :r FILENAME retrieves disk file FILENAME and puts it below the cursor position.
5. :r !dir reads the output of the dir command and puts it below the cursor position.
------------------
Lesson 6 SUMMARY
1. Type o to open a line BELOW the cursor and start Insert mode.
Type O to open a line ABOVE the cursor.
2. Type a to insert text AFTER the cursor.
Type A to insert text after the end of the line.
3. The e command moves to the end of a word.
4. The y operator yanks (copies) text, p puts (pastes) it.
5. Typing a capital R enters Replace mode until <ESC> is pressed.
6. Typing ":set xxx" sets the option "xxx". Some options are:
'ic' 'ignorecase' ignore upper/lower case when searching
'is' 'incsearch' show partial matches for a search phrase
'hls' 'hlsearch' highlight all matching phrases
You can either use the long or the short option name.
7. Prepend "no" to switch an option off: :set noic
-----------------
Lesson 7 SUMMARY
1. Type :help or press <F1> or <Help> to open a help window.
2. Type :help cmd to find help on cmd .
3. Type CTRL-W CTRL-W to jump to another window
4. Type :q to close the help window
5. Create a vimrc startup script to keep your preferred settings.
6. When typing a : command, press
參考文獻：
維基百科
知乎--李亮德：https://www.zhihu.com/question/36339816/answer/385944057