Basics of MATLAB and Beyond - Andrew Knight

205 Pages·2006·3.37 MB·English

B A S I C S O F
M
ATLAB®
and Beyond
(cid:1)c 2000byCRCPressLLC
B A S I C S O F
M
®
ATL AB
and Beyond
Andrew Knight
CHAPMAN & HALL/CRC
Boca Raton London New York Washington, D.C.
Library of Congress Cataloging-in-Publication Data
Knight, Andrew (Andrew James), 1961—
Basics of MATLAB and beyond / Andrew Knight.
p. cm.
Includes index. (alk. paper)
ISBNO-8493-2039-9
1. Engitteering mathematics-Data prccessing. 2. MATLAB. I. Title.
TA345.K63 1999
620´.001´5 118-dc2 1 99-31210
CIP
J
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MATLAB is a registered trademark of The MathWorks, Inc.
Preface
This book arose from notes written for matlab(cid:1)R training courses run
within the Australian Defence Science and Technology Organisation.
The book is in two parts. Each part was originally a two-day course,
designedassumingthatstudentswereseatedatacomputerwithmatlab
running.
Part1isanintroductorycoursesuitableforthosewithnoexperience
at all with matlab. It is written in a self contained way; if you go
through the notes, all the new commands and ideas are explained as
they are introduced.
Part 2 is a more advanced course suitable for those who are already
familiar with the basics of matlab. It covers a variety of topics, some
of which you may not be interested in; if so, you should be able to skip
that section without detriment to other sections.
You can get the m-files that accompany this book from the “Down-
load” section of the CRC Press web site (www.crcpress.com). The files
are available in zip or gzipped tar format, and can be extracted using
WinZip on a PC, or by using gunzip and tar on unix. You will need to
put them in a directory where matlab will be able to find them. You
can either use the cd command to move matlab’s working directory to
the directory you extract the files to, or add that directory to matlab’s
search path. (You can display matlab’s current working directory by
matlab is a registered trademark
of The MathWorks, Inc. For product
information, please contact:
The MathWorks, Inc.
24 Prime Park Way
Natick, MA 01760-1500 USA
Tel: [phone]
Fax: [phone]
E-mail: [email protected]
Web: www.mathworks.com
(cid:1)c 2000byCRCPressLLC
typing pwd (print working directory) in the command window.) On a
PC or Macintosh, you can add directories to matlab’s path by clicking
onthepathbrowserbuttonatthetopofthematlabcommandwindow
(it is the button with two folders on it to the left of the question mark
button). In the path browser, select the menu “Path→Add to path”,
then select the directory containing the extracted files using the browse
button (on PCs it is the one with three dots on it), then check the “add
to back” option before pressing “OK”. Then click “File→Save Path”
before you exit the path browser. If you are using another platform you
can use the path command from within matlab (type help path for
instructions). You can install this path each time you start matlab
by putting an appropriate path command in a file called startup.m in a
directorycalledmatlabsituatedimmediatelybelowyourhomedirectory.
Many of the graphical examples in this book assume that the figure
windowisempty. Toensureanemptyfigurewindowissuethecommand:
clf
which stands for “clear figure”. If you find that the figure window is
obscured by your command window, try shrinking both windows. Or
you can type:
shg
(show graphic) to bring the graphics window to the front. The compan-
ion software implements an even shorter abbreviation; type
s
to bring the graphics window to the front
If, on a PC or Macintosh, the figure window is at the front of the
screen, or if it has the current focus, just start typing and matlab will
switch to the command window and accept your typing.
Words appearing in this book in typewriter font, for example, type,
represent matlab commands that you can type in, or output produced
by matlab.
Andrew Knight
(cid:1)c 2000byCRCPressLLC
About the Author
The author completed a Ph.D. in plasma physics at the Flinders Uni-
versity of South Australia in the days before matlab. Consequently, he
knows how much time can be saved when you don’t have to write your
own matrix inversion or polynomial evaluation routines in fortran.
His first exposure to matlab was at the Centre for Plasma Physics
Research at the Swiss Federal Institute of Technology (Ecole Poly-
technique F´ed´erale) in Lausanne, Switzerland, where he continued his
researchinplasmaphysics. OnhisreturntoAustraliatotakeupaposi-
tion with the Maritime Operations Division of the Defence Science and
Technology Organisation, he was given responsibility for research in the
flow noise problem of towed sonar arrays. His current research interests
include sonar signal processing and information displays. He has been
largely responsible for the growth in the use of matlab in his division,
and has conducted training courses in matlab.
(cid:1)c 2000byCRCPressLLC
Contents
I Basics of MATLAB
1 First Steps in MATLAB
1.1 Starting MATLAB
1.2 First Steps
1.3 Matrices
1.4 Variables
1.5 The Colon Operator
1.6 Linspace
1.7 Plotting Vectors
2 Typing into MATLAB
2.1 Command Line Editing
2.2 Smart Recall
2.3 Long Lines
2.4 Copying and Pasting
3 Matrices
3.1 Typing Matrices
3.2 Concatenating Matrices
3.3 Useful Matrix Generators
3.4 Subscripting
3.5 End as a subscript
3.6 Deleting Rows or Columns
3.7 Matrix Arithmetic
3.8 Transpose
4 Basic Graphics
4.1 Plotting Many Lines
4.2 Adding Plots
4.3 Plotting Matrices
4.4 Clearing the Figure Window
4.5 Subplots
(cid:1)c 2000byCRCPressLLC
4.6 Three-Dimensional Plots
4.7 Axes
4.8 Labels
5 More Matrix Algebra
6 Basic Data Analysis
7 Graphics of Functions of Two Variables
7.1 Basic Plots
7.2 Colour Maps
7.3 Colour Bar
7.4 Good and Bad Colour Maps
7.5 Extracting Logical Domains
7.6 Nonrectangular Surface Domains
8 M-Files
8.1 Scripts
8.2 Functions
8.3 Flow Control
8.4 Comparing Strings
9 Data Files
9.1 MATLAB Format
9.2 ASCII Format
9.3 Other Formats
10 Directories
11 Startup
12 Using MATLAB on Different Platforms
13 Log Scales
14 Curve Fitting—Matrix Division
15 Missing Data
16 Polar Plots
17 Fourier Transform
18 Power Spectrum
19 Sounds in MATLAB
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20 Time-Frequency Analysis
21 Line Animation
22 SPTool
23 Handle Graphics
23.1 Custom Plotting Functions
23.2 Set and Get
23.3 Graphical Object Hierarchy
24 Demos
II Beyond the Basics
25 Sparse Arrays
25.1 Example: Airfoil
25.2 Example: Communication Network
26 Text Strings
26.1 String Matrices
26.2 Comparing Strings
26.3 String Manipulations
26.4 Converting Numbers to Strings
26.5 Using Strings as Commands
27 Cell Arrays
28 Structures
28.1 Example: Meteorological Database
28.2 Example: Capturing the List of Variables
29 Multidimensional Arrays
29.1 Generating Multidimensional Grids
29.2 Operations with Multidimensional Arrays
29.3 RGB Images
29.4 Example: Sonar
29.5 Multidimensional Cell Arrays
29.6 Multidimensional Structures
30 Saving and Loading Data
30.1 MATLAB Format
30.2 Other Formats
(cid:1)c 2000byCRCPressLLC