import numpy as np
import matplotlib.pyplot as plt
# ################################################################################
def plot_function():
    # Make data.
    X = np.arange(-5, 5, 0.25)
    Y = np.arange(-5, 5, 0.25)
    X, Y = np.meshgrid(X, Y)
    Z = (X ** 2 + Y - 11) ** 2 + (X + Y ** 2 - 7) ** 2

    # Plot the surface.
    fig = plt.figure()
    ax = fig.gca(projection='3d')
    surf = ax.plot_surface(X, Y, Z, cmap=cm.coolwarm,
                           linewidth=0, antialiased=False)
    ax.set_xlabel('X Label')
    ax.set_ylabel('Y Label')
    ax.set_zlabel('Z Label')
    return X, Y, Z
# ################################################################################
X, Y, Z = plot_function()