import numpy as np
import matplotlib.pyplot as plt


blockLength = 10000000;
nbins = 1000;
a = np.random.normal(0.0, 1.0, blockLength);
plt.figure()
plt.hist(a,bins=nbins,density=True);
plt.suptitle('Gaussian PDF')
plt.xlabel('x')
plt.ylabel('$f_X$(x)')