from sympy import symbols, sin, cos, pi
from spb import *
import numpy as np
x, y = symbols("x, y")
expr = (cos(x) + sin(x) * sin(y) - sin(x) * cos(y))**2
graphics(
    surface(expr, (x, 0, pi), (y, 0, 2 * pi), use_cm=True,
        tx=np.rad2deg, ty=np.rad2deg,
        wireframe=True, wf_n1=20, wf_n2=20),
    backend=PB, xlabel="x [deg]", ylabel="y [deg]",
    aspect=dict(x=1.5, y=1.5, z=0.5))