title: Invert matrix of Fractions with numpy
body: <p>I have an n*n matrix like so:</p>
  <pre><code>[
      [Fraction(1, 1), Fraction(-1, 2)],
      [Fraction(-4, 9), Fraction(1, 1)]
  ]
  </code></pre>
  <p>And I want to find its inverse. Since it has <code>Fraction</code>s in it, doing:</p>
  <pre><code>from numpy.linalg import inv
  inv(M)
  </code></pre>
  <p>Does not work. I get <code>TypeError: No loop matching the specified signature and casting was found for ufunc inv</code></p>