docs: def rotateInZMat(theta_deg):
      """Rotate a vector theta degrees around the z-axis
  
      Equivalent to yaw left
  
      Rotates the vector in the sense that the x-axis is rotated
      towards the y-axis. If looking along the z-axis (which is
      not the way you usually look at it), the vector rotates
      clockwise.
  
      If sitting on the vector [1,0,0], the rotation is towards the left
  
      Input:
      theta_deg   (float) Angle through which vectors should be
                  rotated in degrees
  
      Returns:
      A matrix
  
      To rotate a vector, premultiply by this matrix.
      To rotate the coord sys underneath the vector, post multiply
  
      """
  
      ct = np.cos( np.radians(theta_deg))
      st = np.sin( np.radians(theta_deg))
      rMat = np.array([  [ ct, -st, 0],
                         [ st,  ct, 0],
                         [  0,   0, 1],
                      ])
  
      return rMat