MATLAB Programming

Evaluating Expressions
Evaluating Expressions
This section covers the following topics:
• “Find Alternatives to Using eval” on page 12-33
• “Assigning to a Series of Variables” on page 12-33
• “Short-Circuit Logical Operators” on page 12-33
• “Changing the Counter Variable within a for Loop” on page 12-34
Find Alternatives to Using eval
While the eval function can provide a convenient solution to certain
programming challenges, it is best to limit its use. The main reason is that
code that uses eval is often difficult to read and hard to debug. A second
reason is that eval statements cannot always be translated into C or C++
code by the MATLAB Compiler.
If you are evaluating a function, it is more efficient to use feval than eval.
The feval function is made specifically for this purpose and is optimized to
provide better performance.
For more information: See MATLAB Technical Note 1103, “What Is the
EVAL Function, When Should I Use It, and How Can I Avoid It?” at URL
http://www.mathworks.com/support/tech-notes/1100/1103.html.
Assigning to a Series of Variables
One common pattern for creating variables is to use a variable name suffixed
with a number (e.g., phase1, phase2, phase3, etc.). We recommend using a
cell array to build this type of variable name series, as it makes code more
readable and executes more quickly than some other methods. For example:
for k = 1:800
phase{k} = expression;
end
Short-Circuit Logical Operators
MATLAB has logical AND and OR operators (&& and ||) that enable you to
partially evaluate, or short-circuit, logical expressions. Short-circuit operators
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