Problem:
Find the divergence of the vector field $f(x,y,z)\uvec{i} + g(x,y,z)\uvec{j} + h(x,y,z)\uvec{k}$ where $f(x,y,z) = x^3 y^3$, $g(x,y,z) = \tanh (z)$, and $h(x,y,z) = y-z$
from sympy import *
from sympy.vector import *

C = CoordSys3D('C')
x, y, z = C.x, C.y, C.z
f = x**3*y**3
g = tanh(z)
h = y-z
field = f * C.i + g * C.j + h * C.k
print(divergence(field))
