Plot surface of z=(x^2+y^2)^m for different values of m

I have problem plotting the above function for different values of m. I have an example that I follow but I get stuck defining the function Z and thus receive the following error code:

r=linspace(0,1,21); 
theta=linspace(0,2*pi,63); 
[R,THETA]=meshgrid(r,theta); 
X=R.*cos(THETA);
Y=R.*sin(THETA);
>> m=1/3
>> Z=(X.^2+Y.^2)^m;
surf(X,Y,Z) % rita ytan
axis equal
Error using  ^  (line 52)
Incorrect dimensions for raising a matrix to a power. Check that the matrix is square and the power is a scalar. To perform
elementwise matrix powers, use '.^'.

What am I doing wrong? Thanks in advance!

Answer 1

[DGM]

Almost there

r=linspace(0,1,21); 
theta=linspace(0,2*pi,63); 
[R,THETA]=meshgrid(r,theta); 

X=R.*cos(THETA);
Y=R.*sin(THETA);
m=1/3;
%Z=(X.^2+Y.^2).^m; % elementwise power too
Z = R.^(2*m); % this is equivalent

surf(X,Y,Z) % rita ytan
axis equal

[August Lindberg]

Thank you so much!