       SippMatRotate matrix point vector angle
              Return  the rotation rotation of matrix angle radi-
              ans or degrees about the line given  by  point  and
              vector  starting  in  that point.  If angle is pre-
              fixed with "R", then it is in radians.   If  it  is
              prefixed  with  "D",  then it is in degrees.  If no
              prefix is supplied, then radians is assumed.
