title: Copied variable changes the original?
body: <p>I have a simple problem in Python that is very very strange.</p>
  
  <pre><code>def estExt(matriz,erro):
      # (1) Determinar o vector X das soluções
      print ("Matrix after:");
      print(matriz);
  
      aux=matriz;
      x=solucoes(aux); # IF aux is a copy of matrix, why the matrix is changed??
  
      print ("Matrix before: ");
      print(matriz)
  
  ...
  </code></pre>
  
  <p>As you see below, the matrix <code>matriz</code> is changed in spite of the fact that <code>aux</code> is the one being changed by the function <code>solucoes()</code>.</p>
  
  <p>Matrix before:<br>
  <code>[[7, 8, 9, 24], [8, 9, 10, 27], [9, 10, 8, 27]]</code></p>
  
  <p>Matrix after:<br>
  <code>[[7, 8, 9, 24], [0.0, -0.14285714285714235, -0.2857142857142847, -0.42857142857142705],
    [0.0, 0.0, -3.0, -3.0000000000000018]]</code></p>