Page 75 - A Guide to MATLAB for Beginners and Experienced Users

56 Chapter 4: Beyond the Basics

then the previous definition of h is substituted into the symbolic expression
h(t) before the integration is performed.

Substitution
In Chapter 2 we described how to create an inline function from an expression.
You can then plug numbers into that function, to make a graph or table of
values for instance. But you can also substitute numerical values directly into
an expression with subs. For example,

>>symsaxy;
>> a = xˆ2 + yˆ2;
>> subs(a, x, 2)

ans =
4+y^2
>> subs(a, [x y], [3 4])

ans =
25

More about M-Files

Files containing MATLAB statements are called M-files. There are two kinds
of M-files: function M-files, which accept arguments and produce output, and
script M-files, which execute a series of MATLAB statements. Earlier we cre-
ated and used bothtypes. In this section we present additional information
on M-files.

Variables in Script M-Files

When you execute a script M-file, the variables you use and define belong
to your Workspace; that is, they take on any values you assigned earlier in
your MATLAB session, and they persist after the script finishes executing.
Consider the following script M-file, called scriptex1.m:

u=[1234];
Typing scriptex1 assigns the given vector to u but displays no output. Now
consider another script, called scriptex2.m:
n = length(u)