Mann TA Tutorial

7/27/2019 Mann TA Tutorial

1/21

MATLAB Basic


2/21

2

What is MATLAB?

A software environment for interactive numerical computations.

MATLAB stands forMATrix LABoratory

Examples:

Matrix computations and linear algebra

Solving nonlinear equations Numerical solution of differential equations

Mathematical optimization

Statistics and data analysis

Signal processing


3/21

3

Matlab Windows

o Command line

Interface ( Main

Window)

o Editor Window

o Present Directory

o Directory Contents

and Workspace

variables

o Command line

o Command History


4/21


5/21


6/21

6

MATLAB BASICSMATLAB BASICS

Vector:Array with one dimension

Matrix:Array with more than one dimension

Size of an array is specified by the number of rows

and the number of columns, with the number ofrows mentioned first (For example: n x m array).

Total number of elements in an array is theproduct of the number of rows and the number ofcolumns.


7/21

7


1 2

3 4

5 6

a= 3x2 matrix 6 elements

b=[1 2 3 4] 1x4 array 4 elements, row vector

c=

1

3

5

3x1 array 3 elements, column vector

a(2,1)=3 b(3)=3 c(2)=3

Row # Column #


8/21

8


Variables

A region of memory containing an array, which is known

by a user-specified name.

Contents can be used or modified at any time.

Variable names must begin with a letter, followed by anycombination of letters, numbers and the underscore (_)

character.

The MATLAB language is Case Sensitive. NAME, name

and Name are all different variables.


9/21

9

Initializing Variables in Assignment Statements

An assignment statement has the general form

var = expressionExamples:

>> var = 40 * i; >> a2 = [0 1+8];

>> var2 = var / 5; >> b2 = [a2(2) 7 a];

>> array = [1 2 3 4]; >> c2(2,3) = 5;

>> x = 1; y = 2; >> d2 = [1 2];

>> a = [3.4]; >> d2(4) = 4;

>> b = [1.0 2.0 3.0 4.0];

>> c = [1.0; 2.0; 3.0];

>> d = [1, 2, 3; 4, 5, 6]; ; semicolon suppresses the

>> e = [1, 2, 3 automatic echoing of values but

4, 5, 6]; it slows down the execution.



10/21

10


Init ializing with Shortcut Expressions

first: increment: last

Colon operator: a shortcut notation used to initializearrays with thousands of elements

>> x = 1 : 2 : 10;

>> angles = (0.01 : 0.01 : 1) * pi;

Transpose operator: () swaps the rows and columnsof an array

>> f = [1:4];

>> g = 1:4;

>> h = [ g g ];

1 1

2 2

3 3

4 4

h=


11/21

11

Initializing with Keyboard Input

The input function displays a prompt string in theCommand Window and then waits for the user torespond.

my_val = input( Enter an input value: );

in1 = input( Enter data: );

in2 = input( Enter data: ,`s`);



12/21

12


A MATLAB script file (Called an M-file) is a text file thatcontains one or more MATLAB commands and,

optionally, comments.

The file is saved with the extension ".m".

When the filename (without the extension) is issued as acommand in MATLAB, the file is opened, read, and the

commands are executed as if input from the keyboard. The

result is similar to running a program in C.

MATLAB Script Files


13/21

13


A MATLAB function file (called an M-file) is a text file

that contains a MATLAB function and, optionally,

comments.

The file is saved with thefunction name and the usualMATLAB script file extension, ".m".

A MATLAB function may be called from the commandline or from any other M-file.

MATLAB Function Files


14/21

14


When the function is called in MATLAB, the file is

accessed, the function is executed, and control is returnedto the MATLAB workspace.

Since the function is not part of the MATLAB workspace,its variables and their values are not known after control is

returned.

Any values to be returned must be specified in the function

syntax.

MATLAB Function Files


15/21

15


FUNCTIONS in MATLAB

Syntaxfunction [out1, out2, ...] = funname(in1, in2, ...)

Description

function [out1, out2, ...] = funname(in1, in2, ...)

defines function funname that accepts inputs in1, in2, etc.

and returns outputs out1, out2, etc.


16/21

16


EXAMPLE:

function [det_A]=solvexf(r) ;

A=[5 2*r r ; 3 6 2*r-1 ; 2 r-1 3*r];

det_A=det(A);

Calling the function:

[detA]=solvexf(1)


17/21


18/21

18


FOR statement

for a=0:50disp('Hello World')

end

for a=10:10:50

for b=0:0.1:1

disp('MATLAB')

end

end


19/21

19


Summary help command Online help

lookfor keyword Lists related commands which Version and location info

clear Clears the workspace

clc Clears the command window

who, whos Lists content of the workspace Ctrl+c Aborts operation

Continuation

% Comments


20/21

20


-1

2

-2

1

1 2

x(t)

PROBLEM 1-

USE MATLAB TO PLOT THIS SIGNAL


21/21

21


UNIT STEP

FUNCTION

UNIT STEP

DELAYED BY t0

Documents

Mann TA Tutorial