vlt.math.compass2cartesian¶
  vlt.math.compass2cartesian - Convert angles from compass to cartesian
   R = vlt.math.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.