正态分布

import matplotlib.pyplot as plt
import numpy as np

def pq(I, mu, sigma):
    a = 1. / (sigma * np.sqrt(2. * np.pi))
    b = -1. / (2. * sigma ** 2)
    return a * np.exp(b * (I - mu) ** 2)

I =np.linspace(-6,6, 1024)

plt.plot(I, pq(I, 0., 1.), color = 'r', linestyle ='solid')
plt.plot(I, pq(I, 0., .5), color = 'b', linestyle ='dashed')
plt.plot(I, pq(I, 0., .25), color = 'k', linestyle ='dashdot')
plt.show()