Page 62 - A Guide to MATLAB for Beginners and Experienced Users

Presenting Your Results 43

warning message about a nonexistent file the first time you run the script.)
You can also get extraneous output in a diary file if you type CTRL+C to halt a
script containing a diary command. If this happens, you should type diary
off in the Command Window before running the script again.

Presenting Graphics

As indicated in Chapters 1 and 2, graphics appear in a separate window. You
can print the current figure by selecting File : Print... in the graphics window.
Alternatively, the command print (without any arguments) causes the figure
in the current graphics window to be printed on your default printer. Since
you probably don’t want to print the graphics every time you run a script, you
should not include a bare print statement in an M-file. Instead, you should
use a form of print that sends the output to a file. It is also helpful to give
reasonable titles to your figures and to insert pause statements into your
script so that viewers have a chance to see the figure before the rest of the
script executes. For example,
xx = 2*pi*(0:0.02:1);
plot(xx, sin(xx))
% Put a title on the figure.
title(’Figure A: Sine Curve’)
pause
% Store the graph in the file figureA.eps.
print -deps figureA
The form of print used in this script does not send anything to the printer.
Instead, it causes the current figure to be written to a file in the current

working directory called figureA.eps in Encapsulated PostScript format.
This file can be printed later on a PostScript printer, or it can be imported into
another program that recognizes the EPS format. Type help print to see
how to save your graph in a variety of other formats that may be suitable for
your particular printer or application.
As a final example involving graphics, let’s consider the problem of plotting
the functions sin(x), sin(2x), and sin(3x) on the same set of axes. This is a
typical example; we often want to plot several similar curves whose equations
depend on a parameter. Here is a script M-file solution to the problem:

echo on
% Define the x values.
x = 2*pi*(0:0.01:1);