Matlab Basics

The Command Window

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Defining Variables

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Useful Commands

Command	Description	Example (try these out)
who	Lists variables currently defined in MATLAB.	a = 5; b = 6; c = linspace(0,50,10); who
whos	Similar to who, but gives additional information.	a = 5; b = 6; c = linspace(0,50,10); whos
clear	Clear all variables defined.	a = 5; b = 6; c = linspace(0,50,10); clear; % clears all variables who; % displays nothing - no variables defined. a=2; b=5; c=a+b; clear a b; % only clears a and b. c is still here. who; % tells us that c is defined.
clc	Clears the MATLAB workspace. Doesn't clear variables	clc
save	saves variables to a file that can be loaded later.	clear; a=5; b=6; c=a+b*2; save myVariables; % saves all variables to the file "myVariables.mat" save bcVars b c; % saves b and c only to "bcVars.mat"
load	loads variables from a file	clear; a=5; b=6; c=a+b*2; save myVariables; save bcVars b c; clear; load bcVars; % b and c are now defined. who; clear; load myVariables; % a b and c are all defined. who;
help	provides help on how to use a command	help clear; help load; help save;

Basic Operations

MATLAB supports basic operations

Basic Operators

Operator	Description	Examples
+	Addition	1 + 2 % displays 3 b = 1+2; % assigns 3 to the variable b. a = cos(pi)+2.0; % a=1
-	Subtraction	1 - 2 % displays -1 b = 1-2; % assigns -1 to the variable b. a = sqrt(-4*b)+2.0; % a=4
*	Multiplication	2.2*3.3 % displays 6.6 a = 2.2*3.3; % assigns 6.6 to a. b = (pi/4); % assigns sqrt(2)/2 to b.
/	Division	6.6/2.2 % dispays 3.3 a = 6.6/2.2; % assigns 3.3 to a. b = sqrt(a/pi)*exp(a);
^	Power	2^3 % displays 8 a = 2^3 + 243^0.2; % assigns 11 to a.
( )	Parentheses	a = (2+5)*3; % assigns 21 to a b = 2+5*3; % assigns 17 to b c = 2*(a-10); % assigns 22 to c

NOTE: if you are using arrays, then the / and * operators have different behavior! See the page on array arithmetic for more information.

In addition, MATLAB has many built-in functions. Type help elfun at the MATLAB command prompt for a list. Some commonly used functions are given here:

Function	Description
cos	The cosine function
sin	The sine function
tan	The tangent function
sqrt	The square-root, $\sqrt(x)=x^{1/2}$
exp	The exponential function
log10	The base-10 log function, $\log(10^x)=x$
log	The natural log function, $\ln(\exp(x))=x$
abs	The absolute value, $\left|x\right|$

M-Files

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An M-file is a series of MATLAB commands that you save in a file. Then you can re-run them easily and make changes without re-entering everything again. Anything that can be done in the command window can also be done from an m-file.

MATLAB's Path

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