ERROR: Z must be a matrix, not a scalar or vector.

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What's the problem with the following code?
syms x y;
f=input('enter function: ','s');
f = symfun(eval(f), [x y]);
[X,Y]=meshgrid(-10:1:10);
mesh(f);
when i run the above code after entering a function the following error occurs:
Z must be a matrix, not a scalar or vector.

Accepted Answer

Star Strider
Star Strider on 13 May 2017
There is no reason to use the Symbolic Math Toolbox here. Core MATLAB fiunctions will work.
The Code
f=input('enter function: ','s')
% f = 'x.^2 + sin(y)'; % Test Function
f = str2func(['@(x,y)' f]);
[X,Y]=meshgrid(-10:1:10);
mesh(X,Y,f(X,Y));
  2 Comments
Star Strider
Star Strider on 13 May 2017
My pleasure.
You need to be certain that ‘f’ does element-wise operations. Change the str2func call to include a vectorize call:
f = str2func(['@(x,y)' vectorize(f)]);
See the documentation on the various functions to understand how they work, and the documentation on Array vs. Matrix Operations (link) to understand the reason the differences are important.

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