MATLAB: Matlab is not drawing the 3D function correctly with surf command

MATLABsurf

I'm trying to create a 3D graph but it is not being drawn correctly. If I use ezsurf it works fine but with the normal surf function it draws something that seems incorrect. Does anyone know what I did wrong? Thanks in advance. 
a=74
b=58
c=ceil(a/10)
d=ceil(b/20)
v=-2:0.1:2;
w=-2:0.1:2;
[x,y]= meshgrid(v,w);
z = (c*x.^2)-(d*x.^2*y.^2);
figure(1)
surf(x,y,z);
xlabel('X-as');
ylabel('Y-as');
zlabel('Z-as');

Best Answer

z = (c*x.^2)-(d*x.^2.*y.^2);
                 %  ^---- element - wise operation
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