title: Python: how how to divide elements of arrays based on condition?
body: <p>I have two arrays <code>F</code> and <code>P</code> of the same dimension</p>
  <pre><code>F = np.array([[1, 4, 5], 
      [-5, 180, 9],
      [200, 3, 7]])
  
  P = np.array([[11, 3, 9], 
      [4, 2, 77],
      [33, 4, 66]])
  </code></pre>
  <p>I want to divide each element <code>F(i,j)</code> of the matrix <code>F</code> with each element <code>P(i,j)</code> of the matrix <code>P</code> only where <code>F(i,j)&lt;100</code>.</p>
  <pre><code>np.where(F&lt;100)
  (array([0, 0, 0, 1, 1, 2, 2]), array([0, 1, 2, 0, 2, 1, 2]))
  </code></pre>