title: Difference in numpy matrices gives absurd results
body: <p>I have two numpy int matrices a and b, if I create <code>diff = a-b</code> than something weird happens... I have huge values that weren't present in any of the 2 matrices.
  In the picture you can see that the max value of a and b is 52, there are no nan values, but the value diff[0][8] (and many other but not all) is 4294967295.
  <a href="https://i.stack.imgur.com/bPNHz.png" rel="nofollow noreferrer">Screen shots of the results</a></p>
  <p>Any guess?</p>