import numpy as np def runge(x): return 1/(1+x**2) # test it if __name__ == '__main__': # plot the function import matplotlib.pyplot as plt x = np.linspace(-5,5,300) y = runge(x) plt.plot(x,y, 'b',lw=2,alpha=0.5) plt.xlim(-5,5) plt.ylim(0,1) plt.grid() plt.show()