.help dr2tf Jun99 "Slalib Package"
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      SUBROUTINE slDRTF (NDP, ANGLE, SIGN, IHMSF)

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      D R T F
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  Convert an angle in radians to hours, minutes, seconds
  (double precision)

  Given:
     NDP      i      number of decimal places of seconds
     ANGLE    d      angle in radians

  Returned:
     SIGN     c      '+' or '-'
     IHMSF    i(4)   hours, minutes, seconds, fraction

  Notes:

     1)  NDP less than zero is interpreted as zero.

     2)  The largest useful value for NDP is determined by the size
         of ANGLE, the format of DOUBLE PRECISION floating-point
         numbers on the target machine, and the risk of overflowing
         IHMSF(4).  For example, on the VAX, for ANGLE up to 2pi, the
         available floating-point precision corresponds roughly to
         NDP=12.  However, the practical limit is NDP=9, set by the
         capacity of the 32-bit integer IHMSF(4).

     3)  The absolute value of ANGLE may exceed 2pi.  In cases where it
         does not, it is up to the caller to test for and handle the
         case where ANGLE is very nearly 2pi and rounds up to 24 hours,
         by testing for IHMSF(1)=24 and setting IHMSF(1-4) to zero.

  Called:  slDDTF

  P.T.Wallace   Starlink   19 March 1999

  Copyright (C) 1995 Rutherford Appleton Laboratory
  Copyright (C) 1995 Association of Universities for Research in Astronomy Inc.

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