An overview of MATLAB

MATLAB is a commercial "Matrix Laboratory" package which operates as an interactive programming environment. MATLAB is both a computer programming language and a software environment. MATLAB allows you to manage variables, work with different type of data, perform calculations and generate plots. MATLAB is a tool for doing numerical computations with matrices and vectors. MATLAB has a number of add-on software modules ("toolboxes"), that can perform specialized calculations.

Starting MATLAB

To start MATLAB double click on the MATLAB icon. This will start the MATLAB Desktop . From the desktop you can access the Command window , the Workspace window, the Current directory window, as well as the Help Browser and other tools.




The command window is used to type commands, functions and statements. Making sure that the cursor is at the prompt of the command window you can type any command, for example to divide 2 by 3. MATLAB assigns the answer to a variable called "ans", which is the abbreviation for answer. The variable "ans" can be used then form further calculations.

MATLAB retains the previous keystrokes in a command file. The up and down arrow keys can be used to scroll back and forth through the commands.

Workspace

The term workspace refers to the names and values of any variables in use in the current work session.

Variables

Variable names must begin with a letter and must contain less than 32 characters. MATLAB is case sensitive: 

"a"

is not the same as "A."

If this proves to be an annoyance, the command 

casesen

will toggle the case sensitivity off and on.

The sign "=" (called assignment) is used to assign a value to a variable.

Managing the work session

Some of the commands and symbols to manage the work session are:

clc

clears the command windows

clear

clears all variables from memory.

clear var1 var2

clears var1 and var2 from memory

exist('name')

determines if a file or variable exists having the name 'name'

quit

stops MATLAB

who

list variables in memory

whos

list variables ans sizes and indicates if they have imaginary parts

: colon

generates an array having regular spaced elements

, comma

separates elements of an arrays

; semicolon

suppresses screen printing, also denotes a new row in an array

... Ellipsis

continues a line
Several commands can be entered in the same line if they are separated by a comma or semicolon.

Predefined constants

MATLAB has several predefined constants:

Saving and retrieving your workspace

If you want to stop using MATLAB but continue the session at a later time, you must use the save and load commands. Typing 

save

causes MATLAB to save the workspace variables, i.e. the variables name, their sizes and their values in a binary file called matlab.mat. Only MATLAB can read the *.mat files. To retrieve your workspace variable, type 

load

Note: it is important to know the locations of the files you use with MATLAB. File location frequently causes problems. You can display the contents of the current directory by typing 

dir

and the path by typing 

path
or by looking at the toolbar as detailed below.

Menus and the toolbar

A menu can be found across the top of the desktop, the group of icons displayed below it is the toolbar. To the right of the toolbar a box displays the current directory.

Depending on the actions executed MATLAB will generate other type of windows. Such is the case when:

For each window type MATLAB will change its menu, this means that MATLAB's menus are context sensitive.

Using MATLAB

You can perform operations in MATLAB in two different ways:

  1. Computing with MATLAB (Interactive mode)

    In the interactive mode all commands are entered directly in the command window.

  2. Programming in MATLAB

    By running a MATLAB program (script file). The MATLAB file ( *.m) contains MATLAB commands. Running your program is equivalent to typing all the commands, one at a time, at the command window prompt. You can run the file by typing its name at the command window prompt.

References