title: Custom multiplication and numpy
body: <p>Suppose I have my own multiplication between two Python objects <code>a</code> and <code>b</code>, let's call it <code>my_multiplication(a, b)</code>.</p>
  <p>How can I perform a matrix multiplication using numpy where <code>my_multiplication</code> is performed instead of the usual <code>*</code>? Is that even possible?</p>
  <p><strong>Addendum:</strong> Would I still benefit from numpy's speed then?</p>