Digital Signal Processing : Introduction to MATLAB pot

BEIT, 6th SemesterMatlab Basics... A/B is valid and equals A.B -l for same size square matrices A & B... Few methods to create vector LINSPACEx1, x2: generates a row vector of 100 linea

-External Interface

-Optional Toolbox for Signal Processing,

System analysis, Image Processing

How many windows?

BEIT, 6th Semester

MATLAB Windows

characterized by ‘>>’ command prompt

 Edit window: where programs are written

and saved as ‘M-files’

 Graphics window: shows figures,

alternately known as Figure window

Command Window

Figure Window

Edit Window

BEIT, 6th Semester

Matlab Basics

MATLAB Basics: Variables

 Variables:

-Variables are assigned numerical values

by typing the expression directly

 Global Variables

 Local Variables

 Matrices : Basic building block

 Elements are entered row-wise

BEIT, 6th Semester

Basics Matrices

 Special Matrices

null matrix: M = [];

nxm matrix of zeros: M = zeros(n,m);

nxm matrix of ones: M = ones(n,m);

nxn identity matrix: M = eye(n);

Try these Matrices

[eye(2);zeros(2)],[eye(2);zeros(3)], [eye(2),ones(2,3)]

Matrix Operations

 Matrix operations:

A+B is valid if A and B are of same size A*B is valid if A’s number of columns equals B’s number of rows.

A/B is valid and equals A.B -l for same size square matrices A & B.

 Element by element operations:

.* , / , ^ etc

a = [1 2 3], b = [2 2 4],

BEIT, 6th Semester

Vectors

Few methods to create vector

 LINSPACE(x1, x2): generates a row vector of 100 linearly equally spaced points between x1 and x2.

 LINSPACE(x1, x2, N): generates N points

between x1 and x2.

 LOGSPACE(d1, d2): generates a row vector of 50

logarithmically equally spaced points between

decades 10^d1 and 10^d2.

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Waveform representation

2D Plotting

 plot: creates linear continuous plots of

vectors and matrices;

 plot(t,y): plots the vector t on the x-axis

versus vector y on the y-axis

 To label your axes and give the plot a title, type

xlabel('time (sec)') ylabel('step response') title('My Plot')

 Change scaling of the axes by using the

Example: Draw sine wave

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Matlab Plot

Example: Discrete time signal

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Matlab Plot

Example: Draw unit step and delayed

unit step functions

 n=input('enter value of n')

 t=0:1:n-1;

 y1=ones(1,n); %unit step

 y2=[zeros(1,4) ones(1,n-4)]; %delayed unit step

BEIT, 6th Semester

Matlab Plot

Functions

BEIT, 6th Semester

Scripts and Functions

 Script files are ‘M-files’ with some valid

MATLAB commands

 Generally work on global variables present

in the workspace

 Results obtained after executing script

files are left in the workspace

Scripts and Functions

 Function files are also ‘M-files’ but with local variables

 Syntax of defining a function

function [output variable] =

function_name (input variable)

 File name should be exactly same as function name

BEIT, 6th Semester

Example : user defined function

 Assignment is the method of giving a value to a variable You have already seen this in the

interactive mode We write x=a to give the value

of a to the value of x Here is a short program

illustrating the use of assignment

Loops, flows:

for m=1:10:100

num = 1/(m + 1) end

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Recapitulate

Few in-built Matlab functions

BEIT, 6th Semester

Practice

1>Draw a straight line satisfying the equation: y = 3*x + 10

2> Create matrices with zeros, eye and ones

3>Draw a circle with radius unity (use cos θ for x axis, sin θ for y axis)

4>Draw a cosine wave with frequency 10kHz Use both ‘plot’ and

‘stem’ functions to see the difference.

5>Multiply two matrices of sizes 3x3.

6>Plot the parametric curve x(t) = t, y(t) = exp(-t/2) for 0<t<pi/2

using ezplot

7>Plot a cardioid r(θ) = 1 + cos(θ) for 0< θ <pi/2