ENG1060 Study Guide - Final Guide: Le Cell, Regular Expression, Imaginary Number
9 May 2018
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Matlab Cheat Sheet
Some nifty commands
clc Clear command window
clear Clear system memory
clear x Clear x from memory
commandwindow open/select commandwindow
whos lists data structures
whos x size, bytes, class and attributes of x
ans Last result
close all closes all figures
close(H) closes figure H
winopen(pwd) Open current folder
class(obj) returns objects class
save filename saves all variables to .mat file
save filename x,y saves x,y variables to .mat file
save -append filename x appends x to .mat file
load filename loads all variables from .mat file
ver Lists version and toolboxes
beep Makes the beep sound
doc function Help/documentation for function
docsearch string search documentation
web google.com opens webadress
inputdlg Input dialog box
methods(A) list class methods for A
Statistical commands
distrnd random numbers from dist
distpdf pdf from dist
distcdf cdf dist
distrnd random numbers from dist
hist(x) histogram of x
histfit(x) histogram and
*Standard distributions (dist): norm, t, f, gam, chi2, bino
*Standard functions: mean,median,var,cov(x,y),corr(x,y),
*quantile(x,p) is not textbook version.
(It uses interpolation for missing quantiles.
Keyboard shortcuts
edit filename Opens filename in editor
Alt Displays hotkeys
F1 Help/documentation for highlighted function
F5 Run code
F9 Run highlighted code
F10 Run code line
F11 Run code line, enter functions
Shift+F5 Leave debugger
F12 Insert break point
Ctrl+Page up/down Moves between tabs
Ctrl+shift Moves between components
Ctrl+C Interrupts code
Ctrl+D Open highlighted codes file
Ctrl+ R/T Comment/uncomment line
Ctrl+N New script
Ctrl+W Close script
Ctrl+shift+d Docks window
Ctrl+shift+u Undocks window
Ctrl+shift+m max window/restore size
Built in functions/constants
abs(x) absolute value
pi 3.1415...
inf ∞
eps floating point accuracy
1e6 106
sum(x) sums elements in x
cumsum(x) Cummulative sum
prod Product of array elements
cumprod(x) cummulative product
diff Difference of elements
round/ceil/fix/floor Standard functions..
*Standard functions: sqrt, log, exp, max, min, Bessel
*Factorial(x) is only precise for x < 21
Cell commands A cell can contain any variable type.
x=cell(a,b) a×b cell array
x{n,m} access cell n,m
cell2mat(x) transforms cell to matrix
cellfun(’fname’,C) Applies fname to cells in C
cellfun
Strings and regular expressions
strcomp compare strings (case sensitive)
strcompi compare strings (not case sensitive)
strncomp as strcomp, but only n first letters
strfind find string within a string
, gives start position
regexp Search for regular expression
Logical operators
&& Short-Circuit AND.
&AND
|| Short-Circuit or
|or
~not
== Equality comparison
~= not equal
isa(obj, ’class_name’) is object in class
*Other logical operators: <,>,>=,<=
*All above operators are elementwise
*Class indicators: isnan, isequal, ischar, isinf, isvector
, isempty, isscalar, iscolumn
*Short circuits only evaluate second criteria if
first criteria is passed, it is therefore faster.
And useful fpr avoiding errors occuring in second criteria
*non-SC are bugged and short circuit anyway
Variable generation
j:k row vector [j,j+1,...,k]
j:i:k row vector [j,j+i,...,k],
linspace(a,b,n) n points linearly spaced
and including a and b
NaN(a,b) a×b matrix of NaN values
ones(a,b) a×b matrix of 1 values
zeros(a,b) a×b matrix of 0 values
meshgrid(x,y) 2d grid of x and y vectors
[a,b]=deal(NaN(5,5)) declares a and b
global x gives x global scope
Tables
T=table(var1,var2,...,varN) Makes table*
T(rows,vars) get sub-table
T{rows,vars} get data from table
T.var or T.(varindex) all rows of var
T.var(rows) get values of var from rows
summary(T) summary of table
T.var3(T.var3>5)=5 changes some values
T.Properties.Varnames Variable names
T = array2table(A) ! make table from array
T = innerjoin(T1,T2) innerjoin
T = outerjoin(T1,T2) outerjoin !
Rows and vars indicate rows and variables.
tables are great for large datasets, because they
use less memory and allow faster operations.
*rowfun is great for tables, much faster than eg. looping
matrix and vector operations/functions
x=[1, 2, 3] 1x3 (Row) vector
x=[1; 2; 3] 3x1 (Column) vector
x=[1, 2; 3, 4] 2x2 matrix
x(2)=4 change index value nr 2
x(:) All elements of x (same as x)
x(j:end) j’th to last element of x
x(2:5) 2nd to 5th element of x
x(j,:) all j row elements
x(:,j) all j column elements
diag(x) diagonal elements of x
x.*y Element by element multiplication
x./y Element by element division
x+y Element by element addition
x-y Element by element subtraction
A^n normal/Matrix power of A
A.^n Elementwise power of A
A’ Transpose
inv(A) Inverse of matrix
size(x) Rows and Columns
eye(n) Identity matrix
sort(A) sorts vector from smallest to largest
eig(A) Eigenvalues and eigenvectors
numel(A) number of array elements
x(x>5)=0 change elemnts >5 to 0
x(x>5) list elements >5
find(A>5) Indices of elements >5
find(isnan(A)) Indices of NaN elements
[A,B] concatenates horizontally
[A;B] concatenates vertically
For functions on matrices, see bsxfun,arrayfun or repmat
*if arrayfun/bsxfun is passed a gpuArray, it runs on GPU.
*Standard operations: rank,rref,kron,chol
*Inverse of matrix inv(A) should almost never be used, use RREF
through \instead: inv(A)b=A\b.
Document Summary
Some nifty commands clc clear clear x commandwindow whos whos x ans close all close(h) winopen(pwd) class(obj) save filename save filename x,y save -append filename x load filename ver beep doc function docsearch string web google. com inputdlg methods(a) Clear x from memory open/select commandwindow lists data structures size, bytes, class and attributes of x. Last result closes all gures closes gure h. Open current folder returns objects class saves all variables to . mat le saves x,y variables to . mat le appends x to . mat le loads all variables from . mat le. Input dialog box list class methods for a random numbers from dist pdf from dist cdf dist random numbers from dist histogram of x histogram and. Statistical commands distrnd distpdf distcdf distrnd hist(x) histfit(x) *standard distributions (dist): norm, t, f, gam, chi2, bino. *quantile(x,p) is not textbook version. (it uses interpolation for missing quantiles. *standard functions: sqrt, log, exp, max, min, bessel.
