MATLAB Programming

4 M-File Programming
Saving the Program
It is usually a good idea to save your program periodically while you are in the
development process. To do this, click File > Save in the Editor/Debugger.
Enter a filename with a .m extension in the Save file as dialog box that
appears and click OK. It is customary and less confusing if you give the M-file
the same name as the first function in the M-file.
Running the Program
Before trying to run your program, make sure that its M-file is on the
MATLAB path. The MATLAB path defines those directories that you want
MATLAB to know about when executing M-files. The path includes all the
directories that contain functions provided with MATLAB. It should also
include any directories that you use for your own functions.
Use the which function to see if your program is on the path:
which drawPlot
D:\matlabR14\work\drawPlot.m
If not, add its directory to the path using the addpath function:
addpath('D:\matlabR14\work')
Now you can run the program just by typing the name of the M-file at the
MATLAB command prompt:
drawPlot(xdata, ydata)
Getting the Bugs Out
In all but the simplest programs, you are likely to encounter some type of
unexpected behavior when you run the program for the first time. Program
defects can show up in the form of warning or error messages displayed in the
command window, programs that hang (never terminate), inaccurate results,
or some number of other symptoms. This is where the second functionality
of the MATLAB Editor/Debugger becomes useful.
The MATLAB Debugger enables you to examine the inner workings of your
program while you run it. You can stop the execution of your program at any
point and then continue from that point, stepping through the code line by
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