compass2cartesian

  COMPASS2CARTESIAN - Convert angles from compass to cartesian

   R = COMPASS2CARTESIAN(C, USERADIANS)

   Converts angles from compass format to cartesian.
   In compass, 0 degrees is up, and angles rotate clockwise.
   In cartesian, 0 degrees is rightward, and angles rotate
   counterclockwise.

   If USERADIANS is 1, radians are used; otherwise, 
   degrees are used.