Introduction to matlab

INTRODUCTION TO MATLAB

Presented by:

S P SIMON

DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERINGNATIONAL INSTITUTE OF TECHNOLOGY

TIRUCHIRAPPALLI-620 015

04/08/23 S.P.Simon-EEE-NITT 2

CONTENTS

DESKTOP TOOLS AND DEVELOPMENT ENVIRONMENT

BASIC PROGRAMMING

INTRODUCTION TO MATLAB ENVIRONMENT

MATHEMATICS

GRAPHICS

INTRODUCTION TO SIMULINK

MATLAB TOOL BOXES



What is MATLAB? A language for technical computing An interactive system whose basic data element is a matrix MATLAB stands for MATrix LABoratory

Typical Uses Math and computation Algorithm development Modeling, simulation, and prototyping Data analysis, exploration, and visualization Scientific and engineering graphics Application development including GUI



Development Environment: This is the set of tools and facilities that help you use MATLAB functions and files. Many of these tools are graphical user interfaces. It includes the MATLAB desktop and Command Window, a command history, an editor and debugger, and browsers for viewing help, the workspace, files, and the search path.

The MATLAB Mathematical Function Library: This is a vast collection of computational algorithms ranging from elementary functions, like sum, sine, cosine, and complex arithmetic, to more sophisticated functions like matrix inverse, matrix eigen values, Bessel functions, and fast Fourier transforms.

The MATLAB Language: This is a high-level matrix/array language with control flow statements, functions, data structures, input/output, and object-oriented programming features. It allows both "programming in the small" to rapidly create quick and dirty throw-away programs, and "programming in the large" to create large and complex application programs.

Graphics: MATLAB has extensive facilities for displaying vectors and matrices as graphs, as well as annotating and printing these graphs. It includes high-level functions for two-dimensional and three-dimensional data visualization, image processing, animation, and presentation graphics. It also includes low-level functions that allow you to fully customize the appearance of graphics as well as to build complete graphical user interfaces on your MATLAB applications.

The MATLAB Application Program Interface (API): This is a library that allows you to write C and Fortran programs that interact with MATLAB. It includes facilities for calling routines from MATLAB (dynamic linking), calling MATLAB as a computational engine, and for reading and writing MAT-files.

THE MATLAB SYSTEM



DESKTOP TOOLS AND DEVELOPMENT ENVIRONMENT



Start Matlab from the “start” menu

The command window is the dynamic command interpreter which allows the user to issue Matlab commands

The variable browser shows which variables currently exist in the workspace

The command history shows which commands have been executed in the past

Variable browser

Commandwindow

Command history



CREATING MATLAB SCRIPTS Commands can be typed directly into the command

window (like a calculator), or they can be grouped together into a script file (or function)

A script is a text file with a “.m” extension (remember to change to your directory before doing any work cd p:/matlab)

A script file can be created using the Matlab editor edit TestScript.m

Just type the commands into the file

The script can be run by typing the name of the script in the command window (or press F5)

TestScript Any variables created in the script will be visible in

the workspace which are viewed in the variable browser



WORKSPACE

workspace = the area of memory used by the MATLAB who = lists the current variables in the workspace clear = clear the workspace save = save the workspace variables to a file. load = load all variables from a specified file.

save my.dat clear clc who load my.dat -mat who



MATRICES IN MATLAB

MATRICES GENERATION

eye - Identity matrix

ones - Matrix with all elements = 1

Contd..

MATHEMATICS


rand – Random matrix zeros - Matrix with all elements = 0

Matrix Index Always starts with 1 (not 0)

Given:

MATHEMATICS


MATRICES OPERATIONS

Given A and B:

Addition Subtraction Product Transpose

MATHEMATICS


THE USE OF “.” – “ELEMENT” OPERATION

Given A:

Divide each element of A by 2

Multiply each element of A by 3

Square each element of A

MATHEMATICS


USEFUL FUNCTIONS

Function Description

rank Matrix rank

det Determinant

null Null space

\ and / Linear equation solution

inv Matrix inverse

eig Eigenvalues and eigenvectors

poly Characteristic polynomial

MATHEMATICS


Given B:

Inverse of B Determinant of B Eigenvalues of B

EXAMPLES

MATHEMATICS


GET HELP FOR USE OF FUNCTIONS

>>help function_name

>>lookfor keyword

MATHEMATICS


SOLVING LINEAR EQUATIONS

Given A and B:

Solve for X, s.t. AX = B Check that AX = B

Note: X = A\B denotes AX = B, X = B/A denotes XA = B

MATHEMATICS


USE OF M FILE

Click to create a new M-File

Extension “.m” A text file containing script or function or program to run You can run more than 1 line of commands at a time

MATHEMATICS


M-FILE AS SCRIPT FILESave file as filename.m

Type what you want to do, eg. Create matrices

If you include “;” at the end of each statement,result will not be shown immediately

MATHEMATICS


RUN THE M-FILE

Run the file by typing the filename in the command window

That’s because the file path is not defined

MATHEMATICS


TO ADD PATHRUN THE M-FILE

Add Folder…

Select the folder where you placed your M-File

File – Set Path…

MATHEMATICS


RUN AGAIN

Notice that the statement thatdoes not have “;” at the end willhave the result shown immediately

Type the M-File name again

MATHEMATICS


RUN AGAIN 2

If you want to see the values ofthe statement that has “;” at the end,simply type the valuable name and press Enter

MATHEMATICS


BASIC PROGRAMMING

COMMANDS PARSED & EXECUTED IN ORDER

% Comments start with "%" character

pause % Suspend execution - hit any key to continue.

keyboard % Pause & return control to command line.

% Type "return" to continue.

break % Terminate execution of current loop/file.

return % Exit current function

% Return to invoking function/command line.

% Comments start with "%" character

pause % Suspend execution - hit any key to continue.

keyboard % Pause & return control to command line.

% Type "return" to continue.

break % Terminate execution of current loop/file.

return % Exit current function

% Return to invoking function/command line.

FLOW CONTROL CONSTRUCTS Logic Control:

IF / ELSEIF / ELSE SWITCH / CASE / OTHERWISE

Iterative Loops: FOR WHILE


BASIC PROGRAMMING

THE IF, ELSEIF AND ELSE STATEMENTS

Works on Conditional statements

Short-circuited in MATLAB - once a condition is true, the sequence terminates.

»if_examp

i, j = imaginary unit ※ Don't use i or j as a variable except for-loop index!!!


SWITCH, CASE, AND OTHERWISE

BASIC PROGRAMMING

More efficient than elseif statements

Only the first matching case is executed

switch input_numcase -1

input_str = 'minus one';case 0

input_str = 'zero';case 1

input_str = 'plus one';case {-10,10} input_str = '+/- ten';otherwise

input_str = 'other value';end

switch input_numcase -1

input_str = 'minus one';case 0

input_str = 'zero';case 1

input_str = 'plus one';case {-10,10} input_str = '+/- ten';otherwise

input_str = 'other value';end

& | ~

Logical operators

< <= > >= == ~= true = 1 false = 0

Relational operators


THE FOR LOOP

Similar to other programming languages

Repeats loop a set number of times (based on index)

Can be nested

N=10;for I = 1:N

for J = 1:N A(I,J) = 1/(I+J-1);

endend

N=10;for I = 1:N

for J = 1:N A(I,J) = 1/(I+J-1);

endend

BASIC PROGRAMMING


THE WHILE LOOP

Similar to other programming languages

Repeats loop a set number of times (based on index)

Can be nested

I=1; N=10;while I<=N

J=1;while J<=N

A(I,J)=1/(I+J-1);J=J+1;

endI=I+1;

end

I=1; N=10;while I<=N

J=1;while J<=N

A(I,J)=1/(I+J-1);J=J+1;

endI=I+1;

end

BASIC PROGRAMMING


Using Array Operations:

Using Loops:

ARRAY OPERATION

Density = Mass(I,J)/(Length.*Width.*Height);Density = Mass(I,J)/(Length.*Width.*Height);

[rows, cols] = size(M); for I = 1:rows

for J = 1:cols Density(I,J) = M(I,J)/(L(I,J)*W(I,J)*H(I,J));

endend

[rows, cols] = size(M); for I = 1:rows

for J = 1:cols Density(I,J) = M(I,J)/(L(I,J)*W(I,J)*H(I,J));

endend

»array_vs_loops

BASIC PROGRAMMING


BASIC PROGRAMMING

M-FILE FUNCTIONS

Function name has the same constraints as variable name ONE function in ONE file cf) subfunction file name > function name The name of the M-file and of the function SHOULD be the same

Function name resolution Check to see if the name is a variable Check to see if the name is a subfunction Check to see if the name is a function on the current directory Check to see if the name is a function on the MATLAB search path


function y = mean(x)% MEAN Average or mean value.

% For vectors, MEAN(x) returns the mean value.

% For matrices, MEAN(x) is a row vector

% containing the mean value of each column.

[m,n] = size(x);

if m == 1

m = n;

end

y = sum(x)/m;

function y = mean(x)% MEAN Average or mean value.

% For vectors, MEAN(x) returns the mean value.

% For matrices, MEAN(x) is a row vector

% containing the mean value of each column.

[m,n] = size(x);

if m == 1

m = n;

end

y = sum(x)/m;

Keyword: function Function Name (same as file name .m)Output Argument(s) Input Argument(s)

Online Help

MATLABCode

»output_value = mean(input_value) Command Line Syntax

STRUCTURE OF A FUNCTION M-FILE

BASIC PROGRAMMING


local and global variables

save as tg.m Declare the variable as global in every function that requires access to it Issue the global command at the top of the M-file (Recommended!!)

function value=tg(x, y) global Z x1 = x^2; y1 = y^2; Z1 = Z^2 value=x1+y1+z1; return

global Z x = 3; y = 4; Z= 5; tg(x, y) x, y, Z

save as test.m and run test!

M-FILE FUNCTIONS

BASIC PROGRAMMING


eval and feval

eval : execute the contents of bracket in command window

for n = 1:12 eval(['M' num2str(n) ' = magic(n)']) end

for n = 0:pi/10:pi m=feval('sin',n); disp([n m]) end

feval : evaluate function by function name and argument(s) in bracket

M-FILE FUNCTIONS

BASIC PROGRAMMING


BASIC 2-D GRAPHICS

Creating a Plot

plot(x, y) = produces a 2D graph of y vs. x

figure = open a new figure window hold on/off = allows you to add plots to an existing graph ans = the variable which stores the results of most recent answer

t = 0:pi/100:2*pi; y = sin(t); plot(t, y)

figure y2 = sin(t - 0.25); plot(t, y2) hold on plot(t, y+y2)

GRAPHICS


plot Command

plot(x1, y1, x2, y2, ...)

plot(x1, y1, 'color_style_marker', x2, y2, 'color_style_marker, ...) color_style_marker = a 1/2/3 character string. color = c, m, y, r, g, b, w, k style = -, --, :, -., none marker = +, o, *, x

y3 = sin(t - 0.5); plot(t, y, t, y2, t, y3)

plot(t, y, 'c--', t, y2, 'r.')

BASIC 2-D GRAPHICS

GRAPHICS


Subplots

clf = clear the current figure window subplot = display multiple plots in the same window

clf y4 = cos(t); subplot(2, 2, 1); plot(t, y) subplot(2, 2, 2); plot(t, y2) subplot(2, 2, 3); plot(t, y3) subplot(2, 2, 4); plot(t, y4)

BASIC 2-D GRAPHICS

GRAPHICS


Axes

grid on = draw the grid lines axis([xmin xmax ymin ymax]) = set scaling for the axes xlabel/ylabel = adds text beside the X-axis/Y-axis

clf t = -pi:pi/100:pi; y = sin(t); plot(t, y) grid on axis([-pi pi -1 1]) xlabel('\pi \leq \itt \leq \pi') ylabel('sin(t)')

BASIC 2-D GRAPHICS

GRAPHICS


plot3(x,y,z) plots x,y,z in 3-dimentional space

t=(0:pi/10:8*pi); x=exp(-t/20).*cos(t); y=exp(-t/20).*sin(t); z=t; figure(1); plot3(x,y,z); xlabel('x'); ylabel('y'); zlabel('z');

view(20,70); view(2); view(3);

Specifies the viewing point in 3-dimentional plot

view(Az,El)

BASIC 3-D GRAPHICS

GRAPHICS


meshgrid(x,y) generates domain for plotting

x=(-5:0.2:5); y=(-5:0.2:5); [X,Y] = meshgrid(x,y); Z= X .* exp(-X.^2 - Y.^2); size(X); size(Y); size(Z);

mesh(Z); mesh(X,Y,Z);

plots colored meshed 3-D graph

mesh(Z)

BASIC 3-D GRAPHICS

GRAPHICS


surf plots 3-d surface graphs

surf(X,Y,Z)

[cs,h]=contour(Z) clabel(cs,h); colorbar;

plots 3-d surface graphs

contour

BASIC 3-D GRAPHICS

GRAPHICS


INTRODUCTION TO SIMULINK

Simulink is a graphical, “drag and drop” environment for building continuous time signal and system simulations.

It allows users to concentrate on the structure of the problem, rather than having to worry (too much) about a programming language.

The parameters of each signal and system block is configured by the user (right click on block)

Signals and systems are simulated over a particular time.

SIMULINK


STARTING SIMULINK

SIMULINK

Type the following at the Matlab command prompt simulink

The Simulink library will appear Note that you can also start Simulink by clicking on the icon on the Matlab toolbar Select

File – New Model To create a new area (model) to build signals and systems


SIGNALS IN SIMULINK

There are two main libraries for manipulating signals in Simulink:

Sources: generate a signal Sinks: display, read or store a signal

SIMULINK


CREATE AND VIEW A CONTINUOUS TIME SIGNAL

Drag Sine Wave source and Scope sink onto the new Simulink Model and connect them (click on Sine Wave block, hold down Ctrl and click on the Scope)

Modify Sine Wave parameters to 2 rad/sec, by right clicking on Sine Wave block and selecting Sin Parameters, and modify frequency

Run the simulationSimulation - Start

Open the scope and leave open while you change parameters (Sine Wave or Simulation Parameters) and re-run

You can save the simulation using File - Save

SIMULINK


MATLAB TOOLBOXES/BLOCK SETS

Simulink Version 6.1 (R14SP1) Aerospace Blockset Version 1.6.1 (R14SP1) Bioinformatics Toolbox Version 1.1.1 (R14SP1) CDMA Reference Blockset Version 1.1 (R14SP1) Communications Blockset Version 3.0.1 (R14SP1) Communications Toolbox Version 3.0.1 (R14SP1) Control System Toolbox Version 6.1 (R14SP1) Curve Fitting Toolbox Version 1.1.2 (R14SP1) Data Acquisition Toolbox Version 2.5.1 (R14SP1) Database Toolbox Version 3.0.1 (R14SP1) Datafeed Toolbox Version 1.6 (R14SP1) Embedded Target for Infineon C166 Microcontrollers Version 1.1.1 (R14SP1) Embedded Target for Motorola HC12 Version 1.1.1 (R14SP1) Embedded Target for Motorola MPC555 Version 2.0.1 (R14SP1) Embedded Target for OSEK VDX Version 1.1.1 (R14SP1) Embedded Target for TI C2000 DSP(tm) Version 1.1.1 (R14SP1) Embedded Target for TI C6000 DSP(tm) Version 2.2.1 (R14SP1) Excel Link Version 2.2.1 (R14SP1) Extended Symbolic Math Version 3.1.1 (R14SP1) Filter Design HDL Coder Version 1.1 (R14SP1) Filter Design Toolbox Version 3.1 (R14SP1) Financial Derivatives Toolbox Version 3.0.1 (R14SP1)

TOOLBOXES



TOOLBOXES

Financial Time Series Toolbox Version 2.1.1 (R14SP1)Financial Toolbox Version 2.4.2 (R14SP1)Fixed-Income Toolbox Version 1.1 (R14SP1)Fixed-Point Toolbox Version 1.1 (R14SP1)Fuzzy Logic Toolbox Version 2.2 (R14SP1)GARCH Toolbox Version 2.0.1 (R14SP1)Gauges Blockset Version 2.0 (R14SP1)Genetic Algorithm Direct Search Toolbox Version 1.0.2 (R14SP1)Image Acquisition Toolbox Version 1.7 (R14SP1)Image Processing Toolbox Version 5.0.1 (R14SP1)Instrument Control Toolbox Version 2.1 (R14SP1)Link for Code Composer Studio Version 1.3.2 (R14SP1)Link for ModelSim Version 1.2 (R14SP1)MATLAB Builder for COM Version 1.1.2 (R14SP1)MATLAB Builder for Excel Version 1.2.2 (R14SP1)MATLAB Compiler Version 4.1 (R14SP1)MATLAB Report Generator Version 2.1.1 (R14SP1)MATLAB Web Server Version 1.2.3 (R14SP1)Mapping Toolbox Version 2.0.3 (R14SP1)Model Predictive Control Toolbox Version 2.1 (R14SP1)Model-Based Calibration Toolbox Version 2.1.2 (R14SP1)Neural Network Toolbox Version 4.0.4 (R14SP1)OPC Toolbox Version 1.1.1 (R14SP1)Optimization Toolbox Version 3.0.1 (R14SP1)Partial Differential Equation Toolbox Version 1.0.6 (R14SP1)



TOOLBOXES

RF Blockset Version 1.0.2 (R14SP1)RF Toolbox Version 1.0.1 (R14SP1)Real-Time Windows Target Version 2.5.1 (R14SP1)Real-Time Workshop Version 6.1 (R14SP1)Real-Time Workshop Embedded Coder Version 4.1 (R14SP1)Robust Control Toolbox Version 3.0 (R14SP1)Signal Processing Blockset Version 6.0.1 (R14SP1)Signal Processing Toolbox Version 6.2.1 (R14SP1)SimMechanics Version 2.2.1 (R14SP1)SimPowerSystems Version 4.0 (R14SP1)Simulink Accelerator Version 6.0.1 (R14SP1)Simulink Control Design Version 1.1 (R14SP1)Simulink Fixed Point Version 5.0.1 (R14SP1)Simulink Parameter Estimation Version 1.1 (R14SP1)Simulink Report Generator Version 2.1.1 (R14SP1)Simulink Verification and Validation Version 1.0.1 (R14SP1)Spline Toolbox Version 3.2.1 (R14SP1)Stateflow Version 6.1 (R14SP1)Stateflow Coder Version 6.1 (R14SP1)Statistics Toolbox Version 5.0.1 (R14SP1)Symbolic Math Toolbox Version 3.1.1 (R14SP1)System Identification Toolbox Version 6.1 (R14SP1)Virtual Reality Toolbox Version 4.0.1 (R14SP1)Wavelet Toolbox Version 3.0.1 (R14SP1)xPC Target Version 2.6.1 (R14SP1)xPC Target Embedded Option Version 2.6.1 (R14SP1)


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