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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
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<TITLE>FEVAL Evaluate a Function
</TITLE>
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<H2>FEVAL Evaluate a Function
</H2>
<P>
Section: <A HREF=sec_freemat.html> FreeMat Functions </A>
<H3>Usage</H3>
The <code>feval</code> function executes a function using its name.
The syntax of <code>feval</code> is
<PRE>
[y1,y2,...,yn] = feval(f,x1,x2,...,xm)
</PRE>
<P>
where <code>f</code> is the name of the function to evaluate, and
<code>xi</code> are the arguments to the function, and <code>yi</code> are the
return values.
Alternately, <code>f</code> can be a function handle to a function
(see the section on <code>function handles</code> for more information).
Finally, FreeMat also supports <code>f</code> being a user defined class
in which case it will atttempt to invoke the <code>subsref</code> method
of the class.
<H3>Example</H3>
Here is an example of using <code>feval</code> to call the <code>cos</code>
function indirectly.
<PRE>
--> feval('cos',pi/4)
ans =
0.7071
</PRE>
<P>
Now, we call it through a function handle
<PRE>
--> c = @cos
c =
@cos
--> feval(c,pi/4)
ans =
0.7071
</PRE>
<P>
Here we construct an inline object (which is a user-defined class)
and use <code>feval</code> to call it
<PRE>
--> afunc = inline('cos(t)+sin(t)','t')
afunc =
inline function object
f(t) = cos(t)+sin(t)
--> feval(afunc,pi)
ans =
-1.0000
--> afunc(pi)
ans =
-1.0000
</PRE>
<P>
In both cases, (the <code>feval</code> call and the direct invokation), FreeMat
calls the <code>subsref</code> method of the class, which computes the requested
function.
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