MATLAB Programming

3 Basic Program Components
MATLAB Expressions
Two specific types of MATLAB expressions covered in this section are
• “String Evaluation” on page 3-28
• “Shell Escape Functions” on page 3-29
String Evaluation
String evaluation adds power and flexibility to the MATLAB language, letting
you perform operations like executing user-supplied strings and constructing
executable strings through concatenation of strings stored in variables.
eval
The eval function evaluates a string that contains a MATLAB expression,
statement, or function call. In its simplest form, the eval syntax is
eval('string')
For example, this code uses eval on an expression to generate a Hilbert
matrix of order n.
t = '1/(m + n - 1)';
for m = 1:k
for n = 1:k
a(m,n) = eval(t);
end
end
Here is an example that uses eval on a statement.
eval('t = clock');
Constructing Strings for Evaluation. You can concatenate strings to create
a complete expression for input to eval. This code shows how eval can create
10 variables named P1, P2, ..., P10, and set each of them to a different value.
for n = 1:10
eval(['P', int2str(n), '= n .^ 2'])
end
3-28