BASICS OF MATLAB

Engr.Mian Shahzad IqbalLecturer ,Telecom Department

University of Engineering & Technology Taxila

In this presentation …•You will identify the different windows in the MATLAB desktop.

•You will learn some of the basics of programming in the MATLAB.

•You will learn to use MATLAB as an interactive calculator.

MATLAB interactive session

VARIABLES

•A Variable in MATLAB is a symbol used to contain a value.

•A scalar variable is a variable that contains a single number.

•A global variable is that variable which is available in the workspace.

•Local variable is that variable which is created by a function and is not available outside the function.

•A string variable is composed of text (alphanumeric characters).

•Logical variables are the variables containing the logical values.

Predefined constants

• The several predefined constants are listed in the table below

Command Description

ans Temporary variable containing the most recent answer.

eps Specifies the accuracy of floating point precision.

i,j The imaginary unit

Inf Infinity

pi The number 3.14

NaN Indicates an undefined numerical result

SCALAR OPERATIONS

• Different operations that MATLAB performs on the scalars are listed, in their order of precedence, in the table below

symbol Operation MATLAB form

^ Exponentiation ab a^b

* Multiplication ab a*b

/ Right division a/b a/b

\ Left division b/a a\b

+ Addition a + b a+b

- Subtraction a - b a-b

The assignment operator

• The = sign in MATLAB is called the assignment or replacement operator.

• It is used to assign the numerical values to different variables in MATLAB.

• The variable on the left-hand side of the = operator is replaced by the right-hand side.

• General rules of using the = operator.

Managing the work session

1. clcclears the command window

2. clearRemoves all variables from the memory.

3. clear var1 var2Removes the variables var1 and var2 from the

memory.4. exist (‘name’)

Determines if a file or variable exists having the name ‘name’. A 1 indicates that a variable exists and 0 indicates variable does not exists.

5. quitstops MATLAB.

6. whoList the variables currently in the memory.

7. whosList the current variables and sizes, and indicates if

they have the imaginary parts.

8. :Generates an array having regularly spaced

elements.9. ,

separates elements of an array. separates several commands on the same line.

10. ;Suppresses screen printing. Denotes a new row in

an array.11. …

continues a line

12. Arrow and control keys.

13. Smart recall.

14. Tab completion.

COMPLEX NUMBER OPERATIONS

• MATLAB handels complex number algebra automatically.

• For example,c1= 1- 2i

is entered as followc1 = 1-2i

• Common errors

Formatting commands

•Table below gives many variants of the format command

Commands Description and example.format short Four decimal digits (the default); 13.6745.format long 16 digits; 17.27549865424597.format short e

Five digits (four decimals) plus exponent; 6.3792e+03.

format long e

16 digits(15 decimals) plus exponent; 6.379243784781294e-04.

format bank Two decimal digits; 126.73.format + Positive, negative or zero; +.format rat Rational approximations; 43/7.format compact Suppresses some line feeds.

format ------------- Resets to less compact display.

FUNCTIONS

The table below lists some of the built-in functions of the MATLAB

Function MATLAB syntaxex exp(x)

sqrt (x)ln x log(x)

log10x Log10(x)cos x cos(x)sin x sin(x)tan x tan(x)cos-1x acos(x)sin-1x asin(x)tan-1x atan(x)

x