title: How to obtain 3D symmetrical points with reference to a plane - Python (NumPy)
body: <p>I have a point cloud with several points that should be symmetrical. So I have 2 question:</p>
  <ol>
  <li>How can I divide the point cloud (given with cartesian coordinates - x,y,z) by the symmetrical plane (ax+by+cz+d=0) ?</li>
  <li>If I have points defined by the arrays x, y and z and the plane ax+by+cz+d=0, how can I get the symmetrical arrays (x',y' and z') to the plane?</li>
  </ol>
  <p>Already have the 2nd question solved. Anyone knows how to locate a point relative to a plane?</p>