Table Of Content1
Matlab Integrated Development
Environment
ChapterOutline
Lesson1.1 BasicsoftheMatlabIntegratedDevelopmentEnvironment 1
Lesson1.2 MatlabScriptFiles 8
Lesson1.3 MatlabEditor—CellMode 17
AnswerstoSelectedExercises 20
Lesson 1.1 Basics of the Matlab Integrated
Development Environment
Objectives
(cid:1) TofamiliarizebeginnersinMatlabwithitsprogrammingenvironment.
(cid:1) To learn how to use Matlab to execute simple commands, create variables, and
displaytheirvalues.
Topics
1.1.1 MatlabIntegratedDevelopmentEnvironment
1.1.2 CreatingScalarVariables
1.1.3 CreatingVectorVariables
1.1.4 CreatingArrayVariables
1.1.1 Matlab Integrated Development Environment
Matlab version 7.12 (R2011a) is used here to explain the integrated development
environment (IDE). Even though this specific version of Matlab has been used
here, other Matlab versions can still be used to follow the discussions presented in
thisbookifyoudonothavethisexactversion.
First launch Matlab. When MATLAB opens you should see four windows: the
Command Window, the Command History, the Workspace, and the Current
MatlabbyExample.DOI:http://dx.doi.org/10.1016/B978-0-12-405212-3.00001-3
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2 MatlabbyExample
Folder. If you do not see these windows, you can direct Matlab to display them by
going to the Menu!Desktop and then click the window you would like to dis-
play,sothatithas atickünext toit. Forexample, ifyouwouldliketodisplaythe
Command Window, go to Menu!Desktop and then click the Command
Window.
Menu
Command Window title bar
In addition to your ability to display the required windows, you can arrange
them in any way you prefer. This can be achieved by clicking the title bar of any
window, dragging it, and placing it in the required location within the Matlab main
window.
‡Exercise11
Display the four windows and arrange them as shown. Remember, the four windows are
the Command Window, the Command History, the Workspace, and the Current
Folder.
‡Thesuperscriptaftertheexercisenumberdenotestheexercisedifficultylevel:1beingbasic,2inter-
mediate,and3beinganadvancedtask.
MatlabIntegratedDevelopmentEnvironment 3
The Command Prompt “..” is displayed in the Command Window. When
the Command Window is active, a blinking cursor appears to the right of the
prompt. The cursor and the prompt signify that Matlab is ready to perform a
computationaloperation.
The Workspace lists all the variables that you have created so far and their
values. Other information is also displayed here, such as the maximum and mini-
mumvaluesofanyvariablesthatarecreated.
The Command History records all of the commands that you have previously
typed at the Command Prompt. You can select one of these commands using the
mouse and execute it in the Command Window by double-clicking it from within
theCommandHistorywindow.
CurrentFolder:YoucandirectMatlabtosetupafolderofyourchoicetobeacur-
rentfolder.Thiswillthenbeyourworkingfolder,whereyoucansaveyourprograms.
ThemainwindowthatcontainsthesefourwindowsiscalledtheMatlabDesktop.
As mentioned earlier, the Matlab Desktop contains four windows: the
Command Window, the Command History, the Current Folder, and the
Workspace.When oneofthese windowsisactive,theremaining windows become
inactive, but the contents of the remaining windows may still be updated if a script
is running.Thetitle bar oftheactivewindow appearsina darkgray color,whereas
thetitlebaroftheinactivewindowappearsinlightgraycolor.Intheprecedingfig-
ure, the Command Window is active and the title bars of the other three windows
aregrayedout(inactive).
The Menu in the Matlab Desktop dynamically changes according to the win-
dowselected(theactivewindow).
ClickontheWorkspacewindowandnotethechangeintheMenu.
Click another time on the Command History window and note the change in
theMenu.
1.1.2 Creating Scalar Variables
Matlab is a short name for Matrix laboratory. As the name indicates, Matlab is a
matrix-based software package, which, infact, considers the scalar variable to be a
131matrix.Ascalarheremeansanumbersuchas“2”or“2100.”
4 MatlabbyExample
Select Command Window by left-clicking on the Command Window. The
Command Window prompt is “..” or “EDU..” for the educational version. To
createascalarvariable,type“x51;”attheCommandPromptandthenpressEnter.
..x51;
This command creates the scalar variable x and assigns the value “1” to it.
Remember, the characters “..” are just the command prompt. The semicolon “;”
is used to direct Matlab not to display the value of the variable x in the Command
Window.Ifyouleavethesemicolonofftheendofacommand,thenitwillbeech-
oed straightaway to the display, which can sometimes be cumbersome for very
largearrays.Alternatively,itsometimescanbeusefultoseetheresultsdisplayed.
Note the changes that happened in the Command Window, the Command
History, and the Workspace windows. The Workspace displays the x variable, its
value, and the maximum and minimum values of the variable. The Command
Historyrecordsthex51;command.
Double-click the variable x in the Workspace. The Variable Editor pops up
and shows the value of the variable. To change the value of the variable x, double-
click on the cell indicated by the black arrow in the following figure and change it
to another value, for example, by typing the numeral “2”. Press Enter. Close the
Variable Editor window by clicking the X at the top right of the Variable Editor
window.
Value
MatlabIntegratedDevelopmentEnvironment 5
Youshouldgetthefollowingfigure.
1.1.3 Creating Vector Variables
Tocreateavectorvariable,typetheMatlabcommand
..y5[2,3,6,9,11,8,5,3,2,21];
attheCommandPromptandthenpressEnter.
Thiscommandcreatesavectorvariablewiththevalues
y5[2,3,6,9,11,8,5,3,2,21]:
TheMatlabdesktoprespondstothiscommandasshowninthefollowingfigure.
Inordertodrawthevectorvariabley,clickontheyvariableintheWorkspaceso
that it is highlighted as in the following figure, then go to Menu !Graphics!
plot(y).Apop-upwindowappearsandplotsthevectory.
6 MatlabbyExample
Exercise21
IntheWorkspacewindowdouble-clickthevariabley.TheVariableEditorpopsupandshows
youthecontentsofthisvariable.Changethecontentsofthevectorytobeasfollows:
2,3,6,9,1,8,5,3,2,21
Drawthevector.Youshouldgetthefollowingfigure.
1.1.4 Creating Array Variables
Tocreateanarrayvariable,typethefollowingMatlabcommand
..Z5[1,2;3,4];
attheCommandPromptandthenpressEnter.
MatlabIntegratedDevelopmentEnvironment 7
Note and make sure that you include the two semicolons and the commas in the
command.
Thiscommandcreatesanarrayvariablewiththefollowingvalues:
Z5 [1 2
3 4]
The Matlab desktop responds as shown in the following figure. In this book, we
willuseuppercaseletterstonamearrays.
To draw the array variable Z, click on the Z variable in the Workspace so as to
highlight it (as shown in the following figure), then go to Menu!Graphics!
mesh(Z). A pop-up window appears and displays the array variable Z as a 3D
mesh. An alternative to using the pop-up menu is to right-click on the Z array in
theWorkspaceandselectmesh(Z)fromthatmenu.
8 MatlabbyExample
Exercise31
In the Workspace, double-click the array variable Z. The Variable Editor pops up and
shows you the contents of this variable. Change the contents of this variable to the
following:
Z5 [1 6
3 4]
DrawthearrayvariableZ.Youshouldnowgetthefollowingfigure.
Lesson 1.2 Matlab Script Files
Objectives
(cid:1) Tolearnhowtocreate,name,save,andexecuteMatlabscriptfiles.
(cid:1) Tolearnhowtomakeyourcodereadableforothers.
(cid:1) TolearnhowtocommentMatlabcode.
Topics
1.2.1 CreatingaScriptFile
1.2.2 NamingaScriptFile
1.2.3 SavingaScriptFile
1.2.4 ExecutingaScriptFile
1.2.5 MatlabCodeReadability
1.2.6 CommentingMatlabCode
MatlabIntegratedDevelopmentEnvironment 9
1.2.1 Creating a Script File
AnM-fileisatextfilethatcontainsacollectionofcommandsthatMatlabexecutes
inasequential order.Ascriptfilehasthefollowingproperties:
(cid:1) Ithasnoarguments(inputdata)anditdoesnotreturnanyvalues(outputs).
(cid:1) The commands executed in the script file have the same effect as if these commands
wereexecutedintheCommandWindow.
(cid:1) ThevariablescreatedbythescriptfilearedisplayedintheWorkspacewindow.
Suppose that we would like to create a script file that contains the following
Matlabcommands.
x51;
y52;
Tocarryoutthistask,dothefollowing.
LaunchMatlab.ThengotoMenu!File!New!Script.
TheMatlabwindowEditorpopsup.Inthiswindow,typetheMatlabcommands
shownintheEditor.
1.2.2 Naming a Script File
Choose a name for this file. The extension for the file must be .m. The following
restrictionsmustbetakenintoconsiderationwhenascriptfileisnamed.
10 MatlabbyExample
(cid:1) Thefilenamemustnotcontainspacesorhyphens(-).
(cid:1) Thefilenamemuststartwithanalphabeticalcharacter(a(cid:2)zorA(cid:2)Z).
(cid:1) The file name must contain only alphabetical characters (a(cid:2)z or A(cid:2)Z), numbers (1(cid:2)9)
orunderscores(_).
(cid:1) Punctuationcharacterssuchascommas(,)orapostrophes(’)arenotallowed,because
manyofthemhavespecialmeaningsinMatlab.
(cid:1) ThefilenamemustbeneitheraMatlabvariablenoranexistingMatlabfunction.
(cid:1) The use of a Matlab reserved word as a file name is not allowed. A list of Matlab
reservedwordsaregivenbelow.
'name' 'across variable'
'node' 'build'
'output' 'description'
'parameter' 'descriptor'
'setup' 'element'
'signal' 'input'
'source' 'interface input'
'terminal' 'interface node'
'through variable' 'interface output'
'variable' 'item type'
'local variable'
(cid:1) TheuseofaMatlabkeywordasafilenameisnotallowed.AlistofMatlabkeywords
aregivenbelow.
'break' 'global'
'case' 'if'
'catch' 'otherwise'
'classdef' 'parfor'
'continue' 'persistent'
'else' 'return'
'elseif' 'spmd'
'end' 'switch'
'for' 'try'
'function' 'while'
To check that the file name you have chosen is not a Matlab keyword or a
Matlabfunction,youcanuseMatlabhelpandsearchunderyourchosenfilename.
Forexample,letuschoosecat.masafilename.TypeattheCommandPrompt
..help cat
Matlab responds and informs you that there is already a function called cat that
concatenates arrays. So you should choose a different file name (and remember to
check that this new name is not restricted in the same way too!). Matlab will warn
against using names that are existing Matlab keywords, but it will not produce a
warning when generating a script with certain function names, for example, the cat
function above. Therefore, for this reason you should always test new user-defined
names that you are unsure about by using the help facility, as shown previously, to
avoidpotentialproblemswithnameclasheswhendebugging.
