import numpy as np

def sinc(x):
    if x == 0.0:
        return 1.0
    else:
        w = np.pi * x
        return np.sin(w) / w

sinc(0.0)

sinc(3.0)

x = np.array([1,2,3])
sinc(x)

vsinc = np.vectorize(sinc)
vsinc(x)

import matplotlib.pyplot as plt
%matplotlib inline

x = np.linspace(-5,5,101)
plt.plot(x, vsinc(x))