Convert an angle in radians to hours, minutes, seconds. (double precision)
     ndp       int          number of decimal places of seconds
     angle     double       angle in radians
     sign      char*        '+' or '-'
     ihmsf     int[4]       hours, minutes, seconds, fraction
     slaDd2tf
  Defined in slamac.h:  D2PI
  P.T.Wallace   Starlink   18 November 1993