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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
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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