from mpl_toolkits import mplot3d
# %matplotlib inline
import numpy as np
import matplotlib.pyplot as plt

def f(x, y):
    return np.sin(np.sqrt(x**2 + y**2))

# 3d Contour plots
x = np.linspace(-6, 6, 30)
y = np.linspace(-6, 6, 30)

X,Y = np.meshgrid(x, y)
Z = f(X,Y)
fig = plt.figure()
ax = plt.axes(projection='3d')
ax.contour3D(X,Y,Z,50,cmap='binary')
ax.set_xlabel('x')
ax.set_ylabel('y')
plt.show()
