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MATLAB Cheat Sheet (DRAFT) by

MATLAB Cheat Sheet based on the book MATLAB: An Introduction with Applications

This is a draft cheat sheet. It is a work in progress and is not finished yet.

MATLAB Enviro­nment

clc
Clear command window
 
clear
Remove items from workspace. You can specify which variables or functions to clear
 
clear all
Fresh start without any leftover variables, functions, or compiled functions
 
input(­'string with a message that is displayed in the Command Window')
Prompts the user for input and returns the entered value
 
fprint­f('­text', values)
Displays formatted text output; supports format specifiers like %d (integer), %f (floating point), %s (string), %c (chara­cter), expone­ntial notation (%e), and \n (newline)
 
disp(v­alue)

disp('­text')
Quickly displays text or variables
 
function [output arguments] = functi­on_­nam­e(input arguments)

  ........
end
Function definition line. Save your function in a function file or at the end of a script file. Function files must have the same name as the 1st function
 
name = @ (arglist) expr
Anonymous function; arglist is a list of indepe­ndent variables separated by comma

Operators and Special Characters

+, -, *, /, ^
Matrix math operations
(
X = DC-1 = D / C
)
 
\
Left division
(
a / b = b \ a
)
(
X = A-1B = A \ B
) or linear optimi­zation
 
.*, ./, .\, .^
Elemen­t-wise operations
 
'
Transpose
 
==, ~=, <, >, <=, >=
Relational operators
If an operand is an array, result is logical array
 
&, |, ~
Logical operations (AND, NOT, OR)
 
;
Suppress output display
 
%
Comment
 
%{  ...  %}
Multiline Comment
 
'Hello'
Definition of a character vector
 
"This is a string­"
Definition of a string
 
str1 + str2
Append strings

Defining and Changing Array Variables

a = 5
Define variable a with value 5
 
x = y
Define variable x with value assigned to y
 
[m:q:n]
(The brackets are optional)
Create a vector with constant spacing by specifying the first term, the spacing, and the last term
 
linspa­ce(­xi,­xf,n)
Creating a vector with constant spacing by specifying the first and last terms, and the number of terms
 
A = [1 2 3; 4 5 6]

A = [1 2 3

         
4 5 6]
Define A as a 2x3 matrix
“space” separates columns “;” or new line separates rows
 
zeros(m,n)
Create m x n matrix of zeros
 
ones(m,n)
Create m x n matrix of ones
 
eye(n)
Create an n x n identity matrix
 
va(k)

va(x, y, z)

va(x, k:p, y, z)
Refers to the kth element of the vector ve
 
va(k) = []
Deletes kth element
 
va(:)
Refers to all the elements of the vector va
 
va(m:n)
Refers to elements m through n of the vector va
 
A(k,p)
Refers to the element at kth row and pth column of matrix A
 
A(:,n)
Refers to the elements in all the rows of column n of the matrix A
 
A(n,:)
Refers to the elements in all the columns of row n of the matrix A
 
A(:,m:n)
Refers to the elements in all the rows between columns m and n of the matrix A
 
A(m:n,:)
Refers to the elements in all the columns between rows m and n of the matrix A
 
A(m:n,p:q)
Refers to the elements in rows m through n and columns p through q of the matrix A.

Plotting

plot(x­,y,­'Li­neS­pec­ifier', 'Prope­rty­Name', Proper­tyV­alue)

plot(x­­,y­,u,­v,t,h))

Line styles:
-, --, :, -
Markers:
+, o, *, ., x, s, d
Colors:
r, g, b, c, m, y, k, w
Property names:
LineWidth
MarkerSize
MarkerEdgeColor
MarkerFaceColor
Plot y vs. x (
LineSp­ecifier
, 
Proper­tyName
, and 
Proper­tyValue
are optional)
LineSp­ecifer
is a combin­ation of line style, marker, and color as a string
 
subplo­t(m­,n,p)
Divides the Figure Window into m × n rectan­gular subplots; the command makes the subplot p current
 
fplot(­'fu­nct­ion­',l­imi­ts,­'line specif­iers')
Plots a function with the form y = f(x) between specified limits (domain of x and, option­ally, the limits of the y axis ([xmin, xmax, ymin, ymax]))
 
line(x­,y,­'Pr­ope­rty­Name', Proper­tyV­alue)
Add additional graph (line) to a plot that already exists
 
hold on

........
hold off
Retain the current plot when adding new plots
 
title(­"­Tit­le")
Add plot title
 
legend­("1s­t", "­2nd­")
Add legend to axes
 
xlabel­("la­bel­")
Add x-axis label
 
ylabel­("la­bel­")
Add y-axis label
 
axis[xmin xmax ymin ymax]
Sets the limits of the x-axis and y-axis on a plot to the specified values
 
close all
Closes all Figure Windows that are open

Control Structures

if
condit­ional expression
  ........
elseif
condit­ional expression
  ........
else

  ........
end
if-els­eif­-el­se-end structure
 
switch
switch expression
  
case
value1
  ........
  
case
value2
  ........
  
otherwise

  ........
end
switch­-case statement
 
for k = f:s:t

  ........
end
for-end loop, where k is the loop variable, f is the value of k in the first pass, s is the increment after each pass, and t is the value of k in the last pass
 
while
condit­ional expression
  ........
end
while-end loop
 
break
Terminate execution of for- or while-loop
 
continue
Pass control to the next iteration of a loop

Special Variables and Constants

ans
Most recent answer
 
pi
The number π
 
eps
The smallest difference between two numbers. Equal to 2^(–52), which is approx­imately 2.2204­e–016
 
Inf
, 
inf
infinity
 
NaN
, 
nan
Not a number (i.e., division by zero)
 
real(x)
Returns the real part of a complex number x
 
imag(x)
Returns the imaginary part of a complex number x

Elementary Math Functions

sqrt(x), nthroo­t(x,n)
Square root, Real nth root of a real number x. (If x is negative n must be an odd integer.)
 
exp(x)
Expone­ntial of x
 
abs(x)
Absolute value of x
 
log(x)
Natural logarithm i.e. Base e logarithm (ln).
 
log2(x), log10(x)
Logarithm with base 2 and 10, respec­tively
 
factor­ial(n)
The factorial function n! (n must be a positive integer.)

Trigon­ometric Math Functions

sin(x), asin(x)
Sine and inverse (argument in radians)
 
sind(x), asind(x)
Sine and inverse (argument in degrees)
 
cos(x), acos(x)
Cosine and inverse (argument in radians)
 
cosd(x), acosd(x)
Cosine and inverse (argument in degrees)
 
tan(x), atan(x)
Tan and inverse (argument in radians)
 
tand(x), atand(x)
Tan and inverse (argument in degrees)
Analogous for the other trigon­ometric functions: 
csc
, 
sec
, and 
cot

Rounding Functions

round(x, n)
Round to the specified number of decimal places (n)
 
fix(x)
Round toward zero
 
ceil(x)
Round toward infinity
 
floor(x)
Round toward minus infinity
 
rem(x,y)
Returns the remainder after x is divided by y
 
sign(x)
Signum function. Returns 1 if x > 0, -1 if x < 0, and 0 if x = 0

Built-In Functions for Handling Arrays

length(A)
Returns the number of elements in the vector A
 
size(A)
Returns a row vector [m,n], where m and n are the size m x n of the array A
 
reshape(A, m,n)
Rearrange a matrix A that has r rows and s columns to have m rows and n columns. r times s must be equal to m times n
 
diag(v)
When v is a vector, creates a square matrix with the elements of v in the diagonal
 
diag(A)
When A is a matrix, creates a vector from the diagonal elements of A.
 

Built-in Functions for Analyzing Arrays

mean(A)
If A is a vector, returns the mean value of the elements of the vector
 
C = max(A)
If A is a vector, C is the largest element in A. If A is a matrix, C is a row vector of column max
 
[d, n] = max(A)
If A is a vector, d is the largest element in A, n is the position of the element (first if there are duplic­ates)
 
min(A)
Returns the smallest element of A
 
[d, n] = min(A)
d is the smallest element in A, n is the position (first if there are duplic­ates)
 
sum(A)
If A is a vector, returns the sum of the elements of the vector
 
sort(A)
If A is a vector, arranges the elements of the vector in ascending order
 
median(A)
If A is a vector, returns the median value of the elements of the vector
 
det(A)
Returns the determ­inant of a square matrix A.
 
dot(a, b)
Calculates the scalar (dot) product of two vectors a and b. The vectors can each be row or column vectors
 
cross(a, b)
Calculates the cross product of two vectors a and b, (a×b). The two vectors must have 3 elements.
 
inv(A)
Returns the inverse of a square matrix A

Built-in Logical Functions

and(A,B)
equivalent to A&B
 
or(A,B)
equivalent to A|B
 
not(A)
equivalent to ~A
 
xor(a,b)
Exclusive or. Returns true (1) if one operand is true and the other is false
 
all(A)
Returns 1 (true) if all elements in a vector A are true (nonzero). Returns 0 (false) if one or more elements are false (zero). If A is a matrix, treats columns of A as vectors, and returns a vector with 1s and 0s
 
find(A)
If A is a vector, returns the indices of the nonzero elements
 
find(A­>d)
If A is a vector, returns the address of the elements that are larger than d (any relational operator can be used)

Polyno­mials and Interp­olation

polyva­l(p,x)
Calculates the value of a polynomial at a point x
 
roots(p)
Determines the root, or roots, of a polynomial
 
p = poly(r)
Determines the coeffi­cients of the polynomial when the roots of a polynomial are known
 
conv(a,b)
Multiplies two polyno­mials
 
[q,r] = deconv­(u,v)
Divides two polyno­mials and returns a vector with the coeffi­cients of the quotient (q) as well as a vector with the coeffi­cients of the remainder polynomial (r)
 
k = polyder(p)
Derivative of a single polynomial.
p is a vector with the coeffi­cients of the polynomial.
k is a vector with the coeffi­cients of the polynomial that is the derivative
 
k = polyde­r(a,b)
Derivative of a product of two polynomials.
a and b are vectors with the coeffi­cients of the polyno­mials that are multiplied.
k is a vector with the coeffi­cients of the polynomial that is the derivative of the product
 
[n d] = polyde­r(u,v)
Derivative of a quotient of two polynomials.
u and v are vectors with the coeffi­cients of the numerator and denomi­nator polynomials.
n and d are vectors with the coeffi­cients of the numerator and denomi­nator polyno­mials in the quotient that is the derivative
 
p = polyfi­t(x­,y,n)
Polynomial curve fitting.
p is the vector of the coeffi­cients of the polynomial that fits the data.
x is a vector with the horizontal coordi­nates of the data points (indep­endent variable).
y is a vector with the vertical coordi­nates of the data points (dependent variable).
n is the degree of the polyno­mial.
 
yi = interp­1(x­,y,­xi,­'me­thod')

Methods:
nearest (xi must be within the domain of x)
linear (xi must be within the domain of x)
spline (xi can have values outside the domain of x)
pchip (xi can have values outside the domain of x)
One-di­men­sional interp­olation (the last character is the number one)
xi is domain