Anonymous Functions with Multiple Inputs ignore some inputs

For example, the function is: , then

But I want to do this: or , and so on

y=@(x,theta) x.^theta
y(2,3)=8  % 2^3=8, succeed

% But I want is :
y(2, theta)  % My ideal output is: 2.^theta but it doesn't work
y(x, 2)   % I need is: x.^2

hope I made it clear enough....

[Bjorn Gustavsson]

@ defines a numerical function, that is a "normal" numerical function that is typically used to return numerical values. In your case it would work perfectly fine to do

theta = [0.5 1 3 2]
x = 2
y(x,theta)

If you want the litteral 2.^theta you should look at what the symbolic toolbox gives you.

[Walter Roberson]

Symbolic is good for this purpose.

In the special case where you do not capture any variables in the anonymous function handle, you could use formula() on the handle, and do text processing to replace all references to the parameter with the numeric constant, and strip the name out of the @() section, and then use str2func. Symbolic toolbox is much more convenient though... especially if you need to get right the possibility that the anonymous function has an anonymous function with the same parameter name

   @(x,y) y.^integral(@(x)x.^2, 0,x)

The @(x)x.^2 should not be replaced when x is being replaced with something constant in the anonymous function...

[Jun Liang]

Thanks, I have used symbolic toolbox to solve this problem.

code:

syms phi(x, theta)
phi(x, theta) = x.^theta;

% phi(2,theta) or phi(x,2) are working