import pylab as pl
xlist = pl.linspace(-3.0, 3.0, 3)
ylist = pl.linspace(-3.0, 3.0, 4)
X, Y = pl.meshgrid(xlist, ylist)
Z = pl.sqrt(X**2 + Y**2)
print(Z)
[[ 4.24264069 3. 4.24264069]
[ 3.16227766 1. 3.16227766]
[ 3.16227766 1. 3.16227766]
[ 4.24264069 3. 4.24264069]]