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diff --git a/math/slalib/dr2tf.f b/math/slalib/dr2tf.f
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+      SUBROUTINE slDRTF (NDP, ANGLE, SIGN, IHMSF)
+*+
+*     - - - - - -
+*      D R T F
+*     - - - - - -
+*
+*  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).  On some architectures, 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 a typical 32-bit 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
+*
+*  Last revision:   26 December 2004
+*
+*  Copyright P.T.Wallace.  All rights reserved.
+*
+*  License:
+*    This program is free software; you can redistribute it and/or modify
+*    it under the terms of the GNU General Public License as published by
+*    the Free Software Foundation; either version 2 of the License, or
+*    (at your option) any later version.
+*
+*    This program is distributed in the hope that it will be useful,
+*    but WITHOUT ANY WARRANTY; without even the implied warranty of
+*    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+*    GNU General Public License for more details.
+*
+*    You should have received a copy of the GNU General Public License
+*    along with this program (see SLA_CONDITIONS); if not, write to the
+*    Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+*    Boston, MA  02110-1301  USA
+*
+*  Copyright (C) 1995 Association of Universities for Research in Astronomy Inc.
+*-
+
+      IMPLICIT NONE
+
+      INTEGER NDP
+      DOUBLE PRECISION ANGLE
+      CHARACTER SIGN*(*)
+      INTEGER IHMSF(4)
+
+*  Turns to radians
+      DOUBLE PRECISION T2R
+      PARAMETER (T2R=6.283185307179586476925287D0)
+
+
+
+*  Scale then use days to h,m,s routine
+      CALL slDDTF(NDP,ANGLE/T2R,SIGN,IHMSF)
+
+      END