import numpy as np
from numpy import pi, sin, cos
from mpl_toolkits.mplot3d import Axes3D
import matplotlib.pyplot as plt

fig = plt.figure()
ax = fig.add_subplot(111, projection='3d')
plot_args = {'rstride': 1, 'cstride': 1, 'cmap':"Blues_r",
             'linewidth': 0.4, 'antialiased': True,
             'vmin': -1.5, 'vmax': 1.5}


x, y = np.mgrid[-6:2:31j, -2:6:31j]*pi
z = 0.5*cos(x/2) + sin(y/4)

ax.plot_surface(x, y/2, z, **plot_args)
ax.plot([-2*pi], [pi], [0.5], marker='o', mfc='w', mec='k', mew=1)
ax.view_init(azim=-60, elev=45)
ax.set_xlim(-6*pi, 2*pi)
ax.set_ylim(-pi, 3*pi)
ax.set_zlim(-2, 2)
plt.xticks([-6*pi, -2*pi, 2*pi],
           [r"$-6\pi$", r"$-2\pi$", r"$2\pi$"])
plt.yticks([-pi, pi, 3*pi],
           [r"$-2\pi$", r"$2\pi$", r"$6\pi$"])
ax.set_zticks([-2, 0, 2])
ax.set_zticklabels([r"$-2$", r"$0$", r"$2$"])
ax.w_xaxis.set_pane_color((1.0, 1.0, 1.0, 0.0)) 
ax.w_yaxis.set_pane_color((1.0, 1.0, 1.0, 0.0)) 
ax.w_zaxis.set_pane_color((1.0, 1.0, 1.0, 0.0))
ax.set_xlabel(r"$x$", fontsize=18)
ax.set_ylabel(r"$y$", fontsize=18)
ax.set_zlabel(r"$z$", fontsize=18)
plt.savefig("Saddle_Point.svg", bbox_inches="tight", transparent=True)
plt.show()