INC151 Matlab Lec1

8/2/2019 INC151 Matlab Lec1

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Lecture 1: Introduction and Script M File Assoc. Prof. Pakorn Kaewtrakulpong, Ph.D.

INC, KMUTT



MATLAB

Introduction Strengths

Weaknesses

Variety Working Environment

Basic Features

Managing the MATLAB workspace Script M Files

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Introduction

MATrix LABoratory numerical computing environment

a scientific calculator

, ,and applied mathematics.

a powerful programming language, excellent graphics, and a wide range of expert knowledge.

Simulink graphical simulation environment

by Mathworks, Inc. (http://www.mathworks.com/)

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Strengths

easy to learn great for testing ideas

state of the art algorithms

large community easy visualization

symbolic maths

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Weaknesses

not very good at hardware interfacing interpreted language

not so good for programming with GUI (Graphic User

nter ace

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Variety

OS MS Windows

Unix or Linux

Toolboxes/Blocksets ToolboxesMATLAB

Blocksets Simulink

ac platform

x86 (or 32 bit) hardware interfacing

faster

x64 large memory model

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Working Environment

workspace

command history

command window

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Help help <topic>

e.g. help,help plot

doc <to ic>

e.g. doc, docplot

Help menu or

toolbutton

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Variable Editor

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Profiler

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File and Directory Comparisons

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Basic Features

Scientific calculator In command window, >> is the prompt.

operators and functions

var a es symbols

Script

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Simple Math Precedence

1. parenthesis

2. operationsI. ^ ower

II. *, / or \ (invert division)III. +, -

3. left→ right

e.g.» 4*25+6*22+2*99

» 3^2-5-6/3+2

» 3^2-5-6/(3+2)

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Variables In MATLAB, variables are not necessarily declared but are

created on a need-to-use basis by its memory manager. Naming convention

case sensitive le itimate characters

letters underscore numbers

begin with letters up to 63 characters (namelengthmax)

e.g.» a=1;b=2;c=3;d=a+b+c» 1_AB=1 % error» A=1,a=2

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Special Variables

ans eps

pi

Inf, inf NaN, nan

i,j

(i2 = -1)

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Basic Data Types

double (defaults), single uint8, uint16, uint32, uint64, int8, int16, int32, int64

char

logical

structure, cell

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Elementary Functions

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Elementary Functions (contd.)

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Examples: Elementary Functions

e.g.» x=sqrt(2)/2

» y=asin(x)

» y_ eg=y 1 0 p

» y=rem(23,4)

» x=-2.6,y1=fix(x),y2=floor(x),y3=ceil(x),y4=round(x)

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Complex Numbers

a+bi (cartesian form) where a and b are real numbers,and i is the imaginary unit.

e.g.

» c1=1-2 ,c2=1-2

» c3=6+sin(.5)i % error

» c3=6+sin(.5)*i

» c4=(c1+c2)/c3

» mag_c1=abs(c1),angle_c1=angle(c1),deg_c1=angle_c1*180/pi

» real_c1=real(c1),imag_c1=imag(c1)

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Other MATLAB symbols

. . . contiuation , comma statement separator

; semicolon statement separator

% line comment <Ctl+C> aborting execution

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Command Window Recalling previous commands

arrow keys

a combination of the leading letter and an up arrow key.

u mentary cursor contro clc clear the command window

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Display Formats

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Display Format Settings

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The MATLAB Search Path

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Managing the MATLAB Workspace clear

clear all variables in the workspace Load and save data

.MAT file save

saves all variables in MATLAB.MAT (MATLAB binary format).

save <MAT-file> must not be the same name as any variable in the workspace; otherwise

that variable will be saved in MATLAB.MAT. <MAT-file> file extensionneed not be put explicitly.

save <MAT-file> <variable 1> <variable 2> ... <variable n> saves only selected variables.

Alternatively, use the menu File/Import data.. or Save workspace as..

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Example: Managing the MATLABWorkspace

e.g.

» clear

» a=1;b=2;c=3

» save

» save myvars a b

» clear

» load myvars

» clear

» load

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Script M Files Commands Usually Used in Script Files or M-Files

echo ontells MATLAB to display or echo commands to thecommand window as they are read and evaluated

echo toggles the echo state

disp(<var>)displays results without identifying variable names(display the values only)

input prompts user for input

return returns control to the executing script m-file or base

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Script M Files (contd.)

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Homework #1

2. write a script that asks for inputs x and n, and calculate the

1. write a line of commands to find the result of

. .

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3. find each range of

double (defaults), singleuint8, uint16, uint32, uint64, int8, int16, int32, int64

Hints: realmin, realmax, intmin, intmax

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