Question

I’m plotting a 3D surface in Python. Here muy1 and muy2 are two matrices created by meshgrid:

[[-5.   -4.75 -4.5  ...,  4.25  4.5   4.75]
 [-5.   -4.75 -4.5  ...,  4.25  4.5   4.75]
 [-5.   -4.75 -4.5  ...,  4.25  4.5   4.75]
 ..., 
 [-5.   -4.75 -4.5  ...,  4.25  4.5   4.75]
 [-5.   -4.75 -4.5  ...,  4.25  4.5   4.75]
 [-5.   -4.75 -4.5  ...,  4.25  4.5   4.75]]

After that a function Z is calculated and plotted

Z=zeros((40,40))
for xi in x:
    temp=1/2*(1-muy1)**2-1/2*(1-muy2)**2;
    print temp;
    Z=Z-temp;
print "Final"
print Z

However I keep getting Z to be 0. What is the reason for this?

Answer 1

temp is zero because it starts with 1/2, which is integer division (resulting in zero). Use 1./2 or 0.5 in both places to prevent that.

temp=1./2*(1-muy1)**2-1./2*(1-muy2)**2