# Author: Alex Gezerlis

# Numerical Methods in Physics with Python (CUP, 2020)

import numpy as np

def paulimatrices():

sigx = np.array([0.,1,1,0]).reshape(2,2)

sigy = np.array([0.,-1j,1j,0]).reshape(2,2)

sigz = np.array([1.,0,0,-1]).reshape(2,2)

return sigx, sigy, sigz

def kron(U,V):

n = U.shape[0]

p = V.shape[0]

W = np.zeros((n*p,n*p), dtype=np.complex64)

for i in range(n):

for k in range(n):

for j in range(p):

for l in range(p):

W[p*i+j,p*k+l] = U[i,k]*V[j,l]

return W

if __name__ == '__main__':

sigx, sigy, sigz = paulimatrices()

allones = np.ones((3,3))

kronprod = kron(sigx,allones); print(kronprod.real)