Basics of MATLAB and Beyond

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contour(x,y,z,30);You may have noticed that the semi-annular region does not appearas a circular segment in our plots. That is because the axes are notsquare. To get square axes you can use the axis square command asdescribed on pages 18 and 120.In this section we have looked at surfaces having domains that couldbe defined in terms of rectangular x and y data matrices. Domainsthat cannot be defined with such matrics are discussed in section 36 onpage 157. For example all x values may not have the same number of yvalues, or the x, y points could be scattered about in an irregular way.8 M-FilesUntil now we have driven matlab by typing in commands directly. Thisis fine for simple tasks, but for more complex ones we can store the typedinput into a file and tell matlab to get its input from the file. Such filesmust have the extension “.m”. They are called m-files. If an m-filecontains matlab statements just as you would type them into matlab,they are called scripts. M-files can also accept input and produce output,in which case they are called functions.8.1 ScriptsUsing your text editor create a file called mfile1.m containing the followinglines:z = peaks;zplot = z;% Do the peaks:clfsubplot(221)ind = find(z
% Do the valleys:subplot(222)ind = find(z>0);zplot = z;zplot(ind) = zeros(size(ind));mesh(zplot)axis tightNow try this in the matlab window:mfile1matlab has executed the instructions in mfile1.m just as if you hadtyped them in. The lines beginning with the percent sign % are ignoredby matlab so they can be used to put comments in your code. Blanklines can be used to improve readability.Any variables created by a script m-file are available in the commandwindow after the m-file completes running:>> clear>> whos>> mfile1>> whosName Size Bytes Classind 1544x1 12352 double arrayz 49x49 19208 double arrayzplot 49x49 19208 double arrayGrand total is 6346 elements using 50768 bytesThese variables are said to exist in the matlab workspace. Scripts canalso operate on variables that already exist in the workspace.You can type the name of a script file within another script file. Forexample you could create another file called mfile2 that contains thetext line mfile1; the contents of mfile1 will then be executed at thatpoint within mfile2.8.2 FunctionsFunctions are m-files that can be used to extend the matlab language.Functions can accept input arguments and produce output arguments.Many of matlab’s own commands are implemented as m-files; try typingtype mean to see how matlab calculates the mean. Functions usec○ 2000 by CRC Press LLC
Page 2 and 3: BASICS OFMATLAB®and Beyondc○ 200
Page 4 and 5: Library of Congress Cataloging-in-P
Page 6 and 7: typing pwd (print working directory
Page 8 and 9: ContentsIBasics of MATLAB1 First St
Page 10 and 11: 20 Time-Frequency Analysis21 Line A
Page 12 and 13: 39Answers to Exercises (Part I)40 A
Page 14 and 15: Set → Getting Started with MATLAB
Page 16 and 17: 1.5 The Colon OperatorTo generate a
Page 18 and 19: matlab will recall the last command
Page 20 and 21: a = zeros(2,3)a =0 0 00 0 0>> b = o
Page 22 and 23: [a a(a)]ans =1 2 3 1 4 74 5 6 2 5 8
Page 24 and 25: a + bans =11 3344 6677 993.8 Transp
Page 26 and 27: 4.2 Adding PlotsWhen you issue a pl
Page 28 and 29: x = [[1 2 3 4]’ [2 3 4 5]’ [3 4
Page 30 and 31: 4.7 AxesSo far we have allowed matl
Page 32 and 33: v =1122>> v*uans =1 2 0 11 2 0 12 4
Page 34 and 35: max returns a vector containing the
Page 36 and 37: s = 100*spiral(3)s =700 800 900600
Page 38 and 39: We can plot the surface z as a func
Page 40 and 41: The contour function plots the cont
Page 42 and 43: m = gray(8);colormap(m)imagesc(1:10
Page 44 and 45: hold onplot3(x(ind),y(ind),z(ind),
Page 46 and 47: z = 5*ones(3,3)z =5 5 55 5 55 5 5>>
Page 50 and 51: variables that are local to themsel
Page 52 and 53: SwitchThe basic form of a switch st
Page 54 and 55: i =i =123136Vectorised Codematlab i
Page 56 and 57: 9.1 MATLAB FormatTo save all the va
Page 58 and 59: 11 StartupEach time you start matla
Page 60 and 61: Where p i is the population for yea
Page 62 and 63: NaNs by leaving them off the plot.
Page 64 and 65: clfpolar(t,gdb)In this case you mus
Page 66 and 67: -0.5000-0.3750-0.2500-0.125000.1250
Page 68 and 69: the periodograms of the blocks, and
Page 70 and 71: plot(y(1:1000))axis([0 1000 -5 5])z
Page 72 and 73: comet(x,y)(You can get a three-dime
Page 74 and 75: By clicking within the panner box a
Page 76 and 77: x = linspace(-1,1,8192);Fs = 1000;y
Page 78 and 79: 23.3 Graphical Object Hierarchymatl
Page 80 and 81: Now we need to get the handles of a
Page 82 and 83: Beyond the BasicsPreludeThis part o
Page 84 and 85: clfgplot(A,[x y])axis off(Try zoomi
Page 86 and 87: str =you’re the one>> str = ’
Page 88 and 89: strrep(str,’go’,’am’)ans =I
Page 90 and 91: ans =3.14159e+100Some additional te
Page 92 and 93: eval(str)v =1 2 3 4 5The eval(str)
Page 94 and 95: Inline objects, like every other ma
Page 96 and 97: a(1,1) = {[1 2 3]}a =[1x3double]or>
Page 98 and 99:
t = {’help’ spiral(3) ; eye(2)
Page 101 and 102:
meteo.Temperatureans =24ans =19.000
Page 103 and 104:
3 >> a = [1 2 ;4 5 6;7 8 9]a =1 2 3
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[x,y] = meshgrid(1:5,1:3)x =1 2 3 4
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ans(:,:,2) =999And to sum over “p
Page 109 and 110:
An Application of RGB ImagesTo see
Page 111 and 112:
You can see that over the 8 time st
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name>> staff(2,1,2).name(5:9)ans =B
Page 115 and 116:
q =7 8 96 1 25 4 3>> save saved_dat
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fid = fopen(’asc.dat’);The fope
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display and the enclosed area is th
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MarkerEdgeColor = auto(and so on)In
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text(-.7,f(-.7),’f(X)’)But we h
Page 125 and 126:
plt(x,f(x/2),’--’)Let us try ca
Page 127 and 128:
Example: findobjThe findobj command
Page 129 and 130:
3. Add the property you want to set
Page 131 and 132:
is numbered from top to bottom. The
Page 133 and 134:
axis ijUsually images like this do
Page 135 and 136:
32.2 Tick Marks and Labelsmatlab’
Page 137 and 138:
clfaxes(’pos’,[.2 .1 .7 .4])x =
Page 139 and 140:
property to [0 top] in the call to
Page 141 and 142:
object’s HorizontalAlignment and
Page 143 and 144:
the required symbols. The m-file ti
Page 145 and 146:
1. Use graphical elements that serv
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uicontrol(’Callback’,’ezplot(
Page 149 and 150:
uicontrol(’Pos’,[110 280 60 19]
Page 151 and 152:
’String’,’0.5’,’Style’,
Page 153 and 154:
function exradio(action)if nargin =
Page 155 and 156:
fail. One place to put variables th
Page 157 and 158:
34.7 Fast DrawingFor fast drawing o
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controlled by guide and which are a
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InvertHardcopy: [ {on} | off ]Paper
Page 163 and 164:
Another option is to use an image f
Page 165 and 166:
yur is the y coordinate of the uppe
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\end{center}\caption{This is the fi
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x 294x1 ...y 294x1 ...z 294x1 ...Gr
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diagram. Such a triangular grid can
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xt = x([1 9 10 1]);yt = y([1 9 10 1
Page 175 and 176:
x = [0 0 .5 0.5 .5 1 11 .5 .5 .5];y
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fac2 = [1 2 61 6 31 4 61 6 5];The r
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t = linspace(0,2*pi,20);x = cos(t);
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N = 20;dt = 2*pi/N;t = 0:dt:(N-1)*d
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colouring of the sphere itself. To
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material dullThe default is materia
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time taken by this routine to calcu
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first row of a by taking the column
Page 191 and 192:
38.3 Debuggingmatlab has a suite of
Page 193 and 194:
10: y = linspace(ycentre - L,ycentr
Page 195 and 196:
We change variables:p ′ = C + Bx.
Page 197 and 198:
Exercise 6 (Page 59)You can generat
Page 199 and 200:
33 ! 36 $ 39 ’ 42 * 45 - 48 034 "
Page 201 and 202:
R = 1; N = 200;[x,y] = meshgrid(lin
Page 203 and 204:
(The plot might take a few seconds
Page 205:
% Reproduce the layers at the diffe
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