KB01: Useful MATLAB Commands

A few Important Commands

Command	Description	Example
demo	Run MATLAB's built-in demonstrations
clc	Clear the Command Window
clf	Clear the contents of the current figure window
clear	Clear the variables in the workspace
CTRL + C	Abort the running program, returns a command prompt
diary	Keep track of everything done in the MATLAB session

General Purpose Commands

General Purpose Commands

Operators and Special Characters

Operator	Description	Example
+	Plus; addition operator
-	Minus; subtraction operator
*	Scalar and matrix multiplication operator
.*	Array multiplication operator
^	Scalar and matrix exponentiation operator
.^	Array exponentiation operator
\	Left-division operator
/	Right-division operator
.\	Array left-division operator
./	Array right-division operator
:	Colon; generates regularly spaced elements and represents an entire row or column
( )	Parentheses; encloses function arguments and array indices; overrides precedence
[ ]	Brackets; enclosures array elements
.	Decimal point
...	Ellipsis; line-continuation operator
,	Comma; separates statements and elements in a row
;	Semicolon; separates columns and suppresses display
%	Percent sign; designates a comment and specifies formatting
_	Quote sign and transpose operator
._	Nonconjugated transpose operator
=	Assignment (replacement) operator

Commands for Managing a Session

Command	Description	Example
clc	Clears Command window
clear	Removes variables from memory
exist	Checks for the existence of file or variable
global	Declares variables to be globa
help	Searches for a help topic
lookfor	Searches help entries for a keyword
quit	Stops MATLAB
who	Lists current variables
whos	Lists current variables (long display)

Special Variables and Constants

Command	Description	Example
ans	Most recent answer
eps	Accuracy of floating-point precision
i, j	The imaginary unit $\sqrt { - 1} $
Inf	Infinity
NaN	Undefined numerical result (not a number)
pi	The number π

System and File Command

Command	Description	Example
cd	Changes current directory
date	Displays current date
delete	Deletes a file
diary	Switches on/off diary file recording
dir	Lists all files in the current directory
load	Loads workspace variables from a file
path	Displays search path
pwd	Displays current directory
save	Saves workspace variables in a file
type	Displays contents of a file
what	Lists all MATLAB files in the current directory
wklread	Read .wkl spreadsheet file

Input/Output and Formatting Commands

Input/Output and Formatting Commands

Input/Output Commands

Command	Description	Example
disp	Displays contents of an array or string
fscanf	Read formatted data from a file
format	Controls screen-display format
fprintf	Performs formatted writes to screen or file
input	Displays prompt and waits for input
;	Suppresses screen printing

Format Codes for fprintf and fscanf

Format	Description	Example
%s	Format as a string
%d	Format as an integer
%f	Format as a floating-point value
%e	Format as a floating-point value in scientific notation
%g	Format in the most compact form: %f or %e
\n	Insert a new line in the output string
\r	Insert a tab in the output string

Numeric Display Formats

Command	Description	Example
format short	Four decimal digits (default)
format long	16 decimal digits
format short e	Five digits plus exponents
format long e	16 digits plus exponents
format bank	Two decimal digits
format +	Positive, negative, or zero
format rat	Rational approximation
format compact	Suppresses some line feeds
format loose	Reset to less compact display mode

Vector, Matrix, and Array Commands

Vector, Matrix, and Array Commands

Array Commands

Command	Description	Example
cat	Concatenates arrays
find	Finds indices of nonzero elements
length	Computes the number of elements
linspace	Creates a regularly spaced vector
logspace	Creates a logarithmically spaced vector
max	Returns largest element
min	Returns smallest element
prod	Product of each column
reshape	Change size
size	Computes array size
sort	Sorts each column
sum	Sums each column

Special Matrices

Command	Description	Example
eye	Creates an identity matrix
ones	Creates an array of ones
zeros	Creates an array of zeros

Matrix Arithmetic

Command	Description	Example
cross	Computes cross products
dot	Computes dot products

Matrix Commands for Solving Linear Equations

Command	Description	Example
det	Computes determinant of an array
inv	Computes the inverse of a matrix
pinv	Computes pseudoinverse of a matrix
rank	Computes rank of matrix
rref	Computes reduced row echelon form

Cell Array Functions

Command	Description	Example
cell	Creates cell array
celldisp	Displays cell array
cellplot	Displays graphical representation of cell array
num2cell	Converts numeric array to cell array
deal	Matches input and output lists
iscell	Identifies cell array

Structure Functions

Command	Description	Example
fieldnames	Returns field names in a structure array
getfield	Returns field contents of a structure array
isfield	Identifies a structure array field
isstruct	Identifies a field from a structure array
setfield	Sets contents of the field
struct	Creates structure array

Plotting Commands

Plotting Commands

Basic xy Plotting Commands

Command	Description	Example
axis	Sets axis limits
fplot	Intelligent plotting of functions
grid	Displays gridlines
plot	Generates xy plot
print	Prints plot or saves plot to a file
title	Puts text at top of plot
xlabel	Adds text label to x-axis
ylabel	Adds text label to y-axis

Plot Enhancement Commands

Command	Description	Example
axes	Creates axes objects
close	Closes the current objects
close all	Closes all plots
figure	Opens a new figure window
gtext	Enables label placement by mouse
hold	Freezes current plot
legend	Legend placement by mouse
refresh	Redraws current figure window
set	Specifies properties of objects such as axes
subplot	Creates plots in subwindows
text	Places string in figure

Specialized Plot Commands

Command	Description	Example
bar	Creates bar chart
loglog	Creates log-log plot
polar	Creates polar plot
semilogx	Creates semilog plot (logarithmic abscissa)
semilogy	Creates semilog plot (logarithmic ordinate)
stairs	Creates stairs pot
stem	Creates stem plot

Colors, Symbols, and Line Types

Color		Symbol		Line
y	yellow	.	point	-	solid
m	magenta	o	circle	:	dotted
c	cyan	x	x-mark	-.	dash-dotted
r	red	+	plus	--	dashed
g	green	*	star
b	blue	d	diamond
w	white	v	triangle (down)
k	black	^	triangle (up)
		<	triangle (left)
		>	triangle (right)
		p	pentagram
		h	hexagram

Three-Dimensional Plotting Commands

Command	Description	Example
contour	Creates contour plot
mesh	Creates three-dimensional mesh surface plot
meshc	Same as mesh with contour plot underneath
meshz	Same as mesh with vertical lines underneath
plot3	Creates three-dimensional plots from lines and points
surf	Creates shaded three-dimensional mesh surface plot
surfc	Same as surf with contour plot underneath
meshgrid	Creates rectangular grid
waterfall	Same as mesh with mesh lines in one direction
zlabel	Adds text label to z-axis

Histogram Functions

Command	Description	Example
bar	Creates a bar chart
hist	Aggregates the data into equally spaced bins
histc	Aggregates the data into unequally spaced bins

Programming

Programming

Logical and Relational Operators

Command	Description	Example
==	Relational operator: equal to
~=	Relational operator: not equal to
<	Relational operator: less than
<=	Relational operator: less than or equal to
>	Relational operator: greater than
>=	Relational operator: greater than or equal to
&	Logical operator: AND
\|	Logical operator: OR
~	Logical operator: NOT
xor	Logical operator: EXCLUSIVE OR

Program Flow Control

Command	Description	Example
break	Terminates execution of a loop
case	Provides alternate execution paths within switch structure
else	Delineates alternate block of statements
elseif	Conditionally executes statements
end	Terminates for, while, and if statements
error	Display error messages
for	Repeats statements a specific number of times
if	Executes statements conditionally
otherwise	Default part of switch statement
return	Return to the invoking function
switch	Directs program execution by comparing point with case expressions
warning	Display a warning message
while	Repeats statements an indefinite number of times

Logical Functions

Command	Description	Example
any	True if any elements are nonzero
all	True if all elements are nonzero
find	Finds indices of nonzero elements
finite	True if elements are finite
isnan	True if elements are undefined
isinf	True if elements are infinite
isempty	True if matrix is empty
isreal	True if all elements are real

M-Files

Command	Description	Example
eval	Interpret strings containing Matlab expressions
feval	Function evaluation
function	Creates a user-defined function M-file
global	Define global variables
nargin	Number of function input arguments
nargout	Number of function output arguments
script	Script M-files

Timing

Command	Description	Example
cputime	CPU time in seconds
clock	Current date and time as date vector
tic, toc	Start, stop a stopwatch timer

Mathematical Functions

Mathematical Functions

Exponential and Logarithmic Functions

Command	Description	Example
exp(x)	Exponential; e^x
log(x)	Natural logarithm; ln(x)
log10(x)	Common (base 10) logarithm; log(x)= log₁₀(x)
sqrt(x)	Square root;

Trigonometric Functions

Command	Description	Example
sin(x)	Sine; sin(x)
cos(x)	Cosine; cos(x)
tan(x)	Tangent; tan(x)
cot(x)	Cotangent; cot(x)
sec(x)	Secant; sec(x)
csc(x)	Cosecant; csc(x)
asin(x)	Inverse sine; arcsin x = sin^–1(x)
acos(x)	Inverse cosine; arcos x = cos^–1(x)
atan(x)	Inverse tangent; arctan x = tan^–1(x)
acot(x)	Inverse cotangent; arccot x = cot^–1(x)
asec(x)	Inverse secant; arcsec x = sec^–1(x)
acsc(x)	Inverse cosecant; arcs x = csc^–1(x)
atan2(x, y)	Four-quadrant inverse tangent

Hyperbolic Functions

Command	Description	Example
sinh(x)	Hyperbolic sine; sinh(x)
cosh(x)	Hyperbolic cosine; cosh(x)
tanh(x)	Hyperbolic tangent; sinh(x)/cosh(x)
coth(x)	Hyperbolic cotangent; cosh(x)/sinh(x)
sech(x)	Hyperbolic secant; 1/cosh(x)
csch(x)	Hyperbolic cosecant; 1/sinh(x)
asinh(x)	Inverse hyperbolic sine; sinh^-1(x)
acosh(x)	Inverse hyperbolic cosine; cosh^-1(x)
atanh(x)	Inverse hyperbolic tangent; tanh^-1(x)
acoth(x)	Inverse hyperbolic cotangent; coth^-1(x)
asech(x)	Inverse hyperbolic secant; sech^-1(x)
acsch(x)	Inverse hyperbolic cosecant; csch^-1(x)

Complex Functions

Command	Description	Example
abs(x)	Absolute value; \|x\|
angle(x)	The angle of a complex number x
conj(x)	The complex conjugate of x
imag(x)	The imaginary part of a complex number x
real(x)	The real part of a complex number x

Statistical Functions

Command	Description	Example
erf(x)	Computes the error function erf(x)
mean	Calculates the average
median	Calculates the median
std	Calculates the standard deviation

Random Number Functions

Command	Description	Example
rand	Generates uniformly distributed random numbers between 0 and 1
randn	Generates normally distributed random numbers

Numeric Functions

Command	Description	Example
ceil	Rounds to the nearest integer toward ∞
fix	Rounds to the nearest integer toward zero
floor	Rounds to the nearest integer toward -∞
round	Rounds towards the nearest integer
sign	Signum function

String Functions

Command	Description	Example
findstr	Finds occurrences of a string
strcmp	Compares strings
char	Creates character string array

Numerical Methods

Numerical Methods

Polynomial and Regression Functions

Command	Description	Example
conv	Computes the product of two polynomials
deconv	Computes the ratio of polynomials
eig	Computes the eigenvalues of a matrix
poly	Computes polynomial from roots
polyfit	Fits a polynomial to data
polyval	Evaluates polynomial and generates error estimates
roots	Computes polynomial roots

Interpolation Functions

Command	Description	Example
interp1	Linear and cubic-spline interpolations of a function of one variable
interp2	Linear interpolation of a function of two variables
spline	Cubic-spline interpolation
unmkpp	Computes the coefficients of cubic-spine polynomials

Root Finding and Minimization

Command	Description	Example
fmin	Finds minimum of single-variable function
fmins	Finds minimum of multivariable function
fzero	Finds zero of single-variable function

Numerical Integration Functions

Command	Description	Example
quad	Numerical integration with adaptive Simpson's rule
quad1	Numerical integration with adaptive Lobatto quadrature
trapz	Numerical integration with the trapezoidal rule

Numerical Differentiation Functions

Command	Description	Example
diff(x)+	Computes the difference between adjacent elements in the vector x
polyder	Differentiates a polynomial, a polynomial product, or a polynomial quotient

ODE Solvers

Command	Description	Example
ode23	Nonstiff, low-order solver
ode45	Nonstiff, medium-order solver
ode113	Nonstiff, variable-order solver
ode23s	Stiff, low-order
ode23t	Moderately stiff, trapezoidal rule solver
ode23b	Stiff, low-order solver
ode15s	Stiff, variable-order solver
odeset	Creates integrator options structure for ODE solvers

Predefined Input Functions

Command	Description	Example
gensig	Generates a periodic sine, square, or pulse input
sawtooth	Generates a periodic sawtooth input
square	Generates a square wave input
stepfun	Generates a step function input

Symbolic Math Toolbox

Symbolic Math Toolbox

Functions for Creating and Evaluating Symbolic Expressions

Command	Description	Example
class	Returns the class of an expression
digits	Sets the number of decimal digits used to do variable precision arithmetic
double	Converts an expression to numeric form
ezplot	Generates a plot of a symbolic expression
findsym	Finds the symbolic variables in a symbolic expression
numden	Returns the numerator and denominator of an expression
sym	Creates a symbolic variable
syms	Creates one or more symbolic variables
vpa	Sets the number of digits used to evaluate expressions

Functions for Manipulating Symbolic Expressions

Command	Description	Example
collect	Collects coefficients of like powers in an expression
expand	Expands an expression by carrying out powers
factor	Factors an expression
poly2sym	Converts a polynomial coefficient vector to a symbolic polynomial
pretty	Displays an expression in a form that resembles typeset mathematics
simple	Searches for the shortest form of an expression
simplify	Simplifies an expression using Maple's simplification rules
subs	Substitutes variables or expressions
sym2poly	Converts an expression to a polynomial coefficient vector

Symbolic Calculus Functions

Command	Description	Example
diff	Returns the derivative of an expression
Dirac	Dirac delta function (unit impulse)
Heaviside	Heaviside function (unit step)
int	Returns the integral of an expression
limit	Returns the limit of an expression
symsum	Returns the symbolic summation of an expression
taylor	Returns the Taylor series of a function

Symbolic Solution of Algebraic and Transcendental Equations

Command	Description	Example
solve	Solves symbolic equations

Symbolic Solution of Differential Equations

Command	Description	Example
dsolve	Returns a symbolic solution of a differential equation or set of equations

Laplace Transform Functions

Command	Description	Example
laplace	Returns the Laplace transform
ilaplace	Returns the inverse Laplace transform

Symbolic Linear Algebra Functions

Command	Description	Example
det	Returns the determinant of a matrix
eig	Returns the eigenvalues (characteristic roots) of a matrix
inv	Returns the inverse of a matrix
poly	Returns the characteristic polynomial of a matrix

Inverse Commands

Inverse Commands

Using lookfor inverse command to list the functions that take the inverse of the matrix.

Functions for Creating and Evaluating Symbolic Expressions

Command	Description	Example
ifft	Inverse discrete Fourier transform
ifft2	Two-dimensional inverse discrete Fourier transform
ifftn	N-dimensional inverse discrete Fourier transform
ifftshift	Inverse FFT shift
asin	Inverse sine, result in radians
asind	Inverse sine, result in degrees
asinh	Inverse hyperbolic sine
acos	Inverse cosine, result in radians
acosd	Inverse cosine, result in degrees
acosh	Inverse hyperbolic cosine
atan	Inverse tangent, result in radians
atan2	Four quadrant inverse tangent
atan2d	Four quadrant inverse tangent, result in degrees
atand	Inverse tangent, result in degrees
atanh	Inverse hyperbolic tangent
acot	Inverse cotangent, result in radian
acotd	Inverse cotangent, result in degrees
acoth	Inverse hyperbolic cotangent
asec	Inverse secant, result in radians
asecd	Inverse secant, result in degrees
asech	Inverse hyperbolic secant
acsc	Inverse cosecant, result in radian
acscd	Inverse cosecant, result in degrees
acsch	Inverse hyperbolic cosecant
invhilb	Inverse Hilbert matrix
ipermute	Inverse permute array dimensions
inv	Matrix inverse
pinv	Pseudoinverse
betaincinv	Inverse incomplete beta function
erfcinv	Inverse complementary error function
erfinv	Inverse error function
gammaincinv	Inverse incomplete gamma function
acde	Inverse of cd elliptic function
asne	Inverse of sn elliptic function
icceps	Inverse complex cepstrum
idct	Inverse discrete cosine transform
ifwht	Fast Inverse Discrete Walsh-Hadamard Transform
unshiftdata	The inverse of SHIFTDATA