Hello, I have noticed a significant speed difference between the array and the matrix implementation of the dot product, especially for not-so-big matrices. For example: In [1]: import numpy as np In [2]: b = np.random.rand(104,1) In [3]: bm = np.mat(b) In [4]: a = np.random.rand(8, 104) In [5]: am = np.mat(a) In [6]: %timeit np.dot(a, b) 1000000 loops, best of 3: 1.74 us per loop In [7]: %timeit am * bm 100000 loops, best of 3: 6.38 us per loop The results for two different PCs (PC1 with windows/EPD6.2-2 and PC2 with ubuntu/numpy-1.3.0) and two different sizes are below: array matrix 8x104 * 104x1 PC1 1.74us 6.38us PC2 1.23us 5.85us 8x10 * 10x5 PC1 2.38us 7.55us PC2 1.56us 6.01us For bigger matrices the timings seem to asymptotically approach. Is it something worth trying to fix or should I just accept this as a fact and, when working with small matrices, stick to array? Thanks, Luca