Introduction to Matlab Lecture 1: Introduction: What is Matlab, History of Matlab, strengths, weakness Getting familiar with the interface: Layout, Pull down menus Creating and manipulating objects: Variables (scalars, vectors, matrices, text strings), Operators (arithmetic, relational, logical) and built-in functions

2.  This course will:
› Introduce the basic functionality of MATLAB
› Demonstrate its utility in scientific research
› Identify interesting concepts and useful
techniques in scientific computing
By the end of the course, you should have
the skills necessary to apply MATLAB to
your research and learn how to extend
its capabilities
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3.  Introduction: What is Matlab, History of Matlab,
strengths, weakness
 Getting familiar with the interface: Layout, Pull down
menus
 Creating and manipulating objects: Variables
(scalars, vectors, matrices, text strings), Operators
(arithmetic, relational, logical) and built-in functions
 Flow control: Conditional and iteration blocks
 Data transport: Importing into/Exporting from the
workspace
 Plotting with Matlab
 M-files and UserDefined functions
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4.  Introduction:
› What is Matlab,
› History of Matlab,
› strengths, weakness
 Getting familiar with the interface:
› Layout,
› Pull down menus
 Creating and manipulating variables

5.  MATLAB is a program for doing numerical
computation.
 It was originally designed for solving linear
algebra type problems using matrices.
 Its name is derived from MATrix LABoratory
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6.  MATLAB has since been expanded and now
has built-in functions for solving problems
requiring
› data analysis,
› signal processing,
› optimization,
› and several other types of scientific computations.
 It also contains functions for 2-D and 3-D
graphics and animation.
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7.  Application kernel, e.g., matlab-7.7
 Computational engine
 Built-in low level algorithms (no source code)
 Includes a variety of graphical capabilities
 Suite with contemporary releases, e.g. R2008b
 Programming language
 Designed to solve problems numerically
(Particularly good for matrix operations)
 Easy to learn and use (Simplier syntax rules than
Fortran or C)
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8.  Auxiliaries – usually bundled with kernel
› Simulink (dynamic systems modeling)
› Stateflow (event and logic-driven modeling)
 Toolboxes - designed for specific applications
› Specialized collections of MATLAB source files
 Developed or supported by MathWorks Inc.
Signal Processing, Optimization, Control System, etc.
 Downloadable third party freeware
Multiple precision arithmetic, robotics, etc.
Resource:
http://www.mathworks.com/matlabcentral/
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9.  Originally written in Fortran
› Author: Cleve Moler, Univ. of New Mexico
 Mathworks, Inc. founded to further develop it.
› Incorporated in 1984
› Core is written in C
› Graphical interface is written in Java
› Runs on many platforms
 Unix – Solaris, SGI, AIX, Digital Unix
 Linux
 Windows
 Mac OS
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10.  MATLAB is relatively easy to learn
 MATLAB code is optimized to be relatively
quick when performing matrix operations
 MATLAB may behave like a calculator or as a
programming language
 MATLAB is interpreted, errors are easier to fix
 Although primarily procedural, MATLAB does
have some object-oriented elements
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11.  MATLAB is NOT a general purpose
programming language
 MATLAB is an interpreted language (making it
for the most part slower than a compiled
language such as C++)
 MATLAB is designed for scientific computation
and is not suitable for some things (such as
parsing text)
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12.  Command window: Type your instructions here
and press ENTER to execute them.
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13.  The MATLAB environment is command
oriented somewhat like UNIX.
 A prompt (>>) appears on the screen and a
MATLAB statement can be entered. When
the <ENTER> key is pressed, the statement is
executed, and another prompt appears.
 If a statement is terminated with a
semicolon ( ; ), no results will be displayed.
Otherwise results will appear before the
next prompt.
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14.  Example
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» a=5;
» b=a/2
b =
2.5000
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15.  Command history: a list of instructions executed by
MATLAB is shown here.
 Workspace: shows a list of variables created by
MATLAB. As you can see, the value of ‘A’ is shown.
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24.  Help
› Launch Matlab Help Window
 Help > Product Help > MATLAB
› See Demos
 Help > Demos
 Or Type help at the Matlab prompt or help followed by
a function name for help on a specific function
 Online:
› Online documentation for Matlab at the MathWorks
website
http://www.mathworks.com/access/helpdesk/help/techdo
c/matlab.html
› There are also numerous tutorials online that are easily
found with a web search.
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28.  “%” is the neglect sign for Matlab (equaivalent
of “//” in C). Anything after it on the same line
is neglected by Matlab compiler.
 Sometimes slowing down the execution is done
deliberately for observation purposes. You can
use the command “pause” for this purpose
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29.  >> clear % clears all objects in
workspace
 >> clear x y % clears values of
objects x and y
 >> clc % clears command
window scroll buffer
 >> which <filename> % finds first occurrence
in search path
 >> who % lists all objects in the
workspace
 >> <command> ; % semicolon →
% execute, no display
in command window
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30.  >> <control> c % stops program
execution
 >> <control> q % stops execution and
exits Matlab
 >> <begin command text > … % three dots → continue
to next line
 >> whos % List known variables plus
their size
 >> help sqrt % Help on using sqrt
 >> lookfor sqrt % Search for keyword sqrt
in on MATLABPATH.
 >> what ('directory') % List MATLAB files in
directory
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31.  >> dir %List all files in current directory
 >> ls % Same as dir
 >> type test %Display the content of test.m
in command window
 >> delete test % Delete test.m
 >> cd a: % Change directory to a:
 >> chdir a: % Same as cd
 >> pwd % Show current directory
 >> which test % Display directory path to
‘closest’ test.m
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32.  Top navigation bar with pull-down menus
 File
 Edit
 Debug
 Desktop
 Window
 Help
 Toolbar with icons
 Current Directory path identified
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33.  File
› New (create new m-file, figure, variable)
› Import Data
› Set Path (folders, directories to search)
› Preferences > Command Window
(number format, scroll buffer size)
 Edit
› Find, Delete, Copy, Paste, etc.
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34.  Desktop
› Choose layout for display of windows
 Original on launch
 Desktop > Save Layout (if you like it) with a name
 Modify original if desired
 Desktop > Save Layout (if you like it) with a name
 Default layout (new in R2008b)
 You can always start over from this configuration
 Desktop > Desktop Layout > Default
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35.  Numerical values
› Sequence of base 10 digits
 Binary, hex representations are character strings
› Period as radix point for floating point
numbers
› Lower case e for power of 10 exponent
 Example: >> x = 123.456e-07
→ x = 0.0000123456
[ not (123.456)*(2.71828,,,)-7 ]
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36.  Complex numbers
› i and j initially set to the square root of -1
Imaginary part has i or j appended
(1+1i) is a single complex number
object
(1+1*i) is a sum of one and current
value of i
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37.  Matrices
› Rectangular arrays of elements
 Indexed by row, then by column
Example: >> A = [ a(1,1) a(1,2); a(2,1) a(2,2)]
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38.  Boolean logicals (Bernoulli variables)
› Truth Values
 1 for true;
 0 for false
› Primary logic symbols
 & logical AND
 == logical equal
 | logical inclusive OR
 ~ logical NOT
› Compound logic symbols
 < Less Than
 <= Less Than or Equal
 > Greater Than
 >= Greater Than or Equal
 == Equal To
 ~= Not Equal To
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39.  MATLAB also supports some logical
functions.
› any(x) returns 1 if any element of x is nonzero
› all(x) returns 1 if all elements of x are nonzero
› isnan(x) returns 1 at each NaN in x
› isinf(x) returns 1 at each infinity in x
› finite(x) returns 1 at each finite value in x
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40.  Separators and delimiters
 [ ] square brackets -- vector and matrix delimiters
 { } curly brackets -- cell delimiter
 ( ) parentheses
* Grouping in compound expressions
* Vector and matrix element indices
* Function argument
 : colon -- index range separator
 ; semicolon -- matrix row separator
 <space> matrix column separator
 , comma -- matrix index, function argument
separator, row vector element separator
 ' ' single quotes -- demarcation of character strings
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41.  Data Types:
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42.  Have not to be previously declared type in a variable
name and type in its value.
 MATLAB will decide on the data type automatically,
so you don’t have to declare its data type.
 Variable names can contain up to 63 characters
 Variable names must start with a letter followed by
letters, digits, and underscores.
 Variable names are case sensitive
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43.  Example of illegal variable names:
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44.  Matlab Special Variables
 ans Default variable name for results
 pi Value of π
 eps Smallest incremental number
 inf Infinity
 NaN Not a number e.g. 0/0
 realmin The smallest usable positive real number
 realmax The largest usable positive real number
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45.  Assignment = a = b (assign b to a)
 Addition + a + b
 Subtraction - a -b
 Multiplication * or.* a*b or a.*b
 Division / or ./ a/b or a./b
 Power ^ or .^ a^b or a.^b
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46.  Type the following expressions into MATLAB at the
command window, and observe the results:
1. >> for = 5
2. >> else =6
3. >> cos = 3;
>> cos(0)
4. >> A = [1,2,3];
>> sum(A)
>> sum = 7;
>> sum(A)

47.  Type the following expressions into MATLAB at
the command window, and observe the
results:
5. >> 5>2
6. >> 5<4
7. >> 1.5<=1.5
8. >> 2>=pi
9. >> 1.8==1.801
10. >> 1.8~=2
11. >> 1.8==1.80000000000000000000000001 (see
what happen)