# Author: Ika, 2013-07-26 from mpl_toolkits.mplot3d import Axes3D from matplotlib import cm from matplotlib.ticker import LinearLocator, FormatStrFormatter import matplotlib.pyplot as plt import numpy as np  fig = plt.figure() ax = fig.gca(projection='3d') ax.set_xlabel('x') ax.set_ylabel('y') # Prepare the data to plot X = np.arange(-8, 8, 0.5) Y = np.arange(-8, 8, 0.5) X, Y = np.meshgrid(X, Y) Z = X*X - Y*Y # Plot the surface surf = ax.plot_surface(X, Y, Z, rstride=1, cstride=1, cmap=cm.jet, linewidth=0, antialiased=False)  # Plot the saddle point x=y=z=np.arange(-0.1,0.1,0.1) ax.plot(x, y, z, 'r+', linewidth=1) ax.text(-2,0,2,r'(0,0,0)',fontsize=20)  fig.colorbar(surf, shrink=0.5, aspect=5)  # Save the figure to the output SVG file plt.savefig("Saddle_Point_SVG.svg");