N = 200

A = np.random.rand(N,N)

B = np.random.rand(N,N)

C = np.random.rand(N,N)

X = np.zeros((N,N))

Y = np.zeros((N,N))

Z = np.zeros((N,N))

x_start = time.clock()

for i in range(N):

for k in range(N):

X[i,k] = np.exp(-(np.dot((A[:,i]-B[:,k]).T, np.dot(C, A[:,i]-B[:,k]))))

x_stop = time.clock()

y_start = time.clock()

for i in range(N):

Y[i,:] = np.diag(np.exp(-(np.dot( (A[:,i] - B.T) , (np.dot(C, (A[:,i] - B.T).T).T).T ) )))

y_stop = time.clock()

z_start = time.clock()

for i in range(N):

Z[i,:] = np.exp(-np.sum((A[:,i] - B.T)*((np.dot(C, (A[:,i] - B.T).T).T).T).T, axis=1))

z_stop = time.clock()

print 'Time:\t', x_stop - x_start, '\t',y_stop - y_start, '\t',z_stop - z_start

print 'Error:\t', np.abs(np.round(np.sum(X - Y))), '\t','\t',np.abs(np.round(np.sum(X - Z))), '\t','\t',np.abs(np.round(np.sum(Y - Z)))