 rotation
  theta   - angle of rotation (radians)

 INPUTS 6 - Creates a 3x3 rotation matrix from 3 angles (around fixed
            axes)
  th1     - angle with respect to X axis
  th2     - angle with respect to Y axis
  th3     - angle with respect to Z axis
      such that R = Rx*Ry*Rz

 INPUTS 7 - Creates the full 3x3 rotation matrix from its first 2 rows
  R       - 2x3 first two rows of the rotation matrix

 INPUTS 8 - Extract the 3 angles of a 3x3 rotation matrix
  R       - 3x3 Rotati