Plot an anonymous function without explicit variable names

Question

I created an anonymous function handle like this:

 f = @(x,y)sqr(x)+sqr(y)

This is a sphere with the two variables x and y. It seems to work since I can call something like

f(2,3)

and MATLAB gives me the right result ans = 13.

In the last step I want to plot that function from let's say -7 to 7 for both x and y. So I call

fmesh(f,[-7 7])

and the right figure pops up. So far, so good.

For some reasons, which I don't wanna specify here, I now want to edit the function handle to this:

f = @(x)sqr(x(1))+sqr(x(2))

This should be the same sphere but this time with the 2 variables x(1) and x(2). Since the function now wants an array as argument I edited the test call

f([2,3])

and it still gives me the right result ans = 13.

But here is the problem: How do you plot the function that wants an array as argument? The same mesh command as before of course fails, since [-7,7] has the wrong dimension. The same goes for [[-7 7] [-7 7]] and [[-7 7];[-7 7]].

How can I get a working plot from that new function handle? Thanks in advance!

Answer 1

You can't get fmesh to pass the x and y values as an array like what you expect. What you can do is to wrap your anonymous function f within another anonymous function which simply re-arranges the input.

g = @(x,y)f([x, y]);
fmesh(g, [-7 7])

A more generalized solution which takes all inputs and puts them into an array would be

g = @(varargin)f([varargin{:}])