djcl.f

      SUBROUTINE sla_DJCL (DJM, IY, IM, ID, FD, J)
*+
*     - - - - -
*      D J C L
*     - - - - -
*
*  Modified Julian Date to Gregorian year, month, day,
*  and fraction of a day.
*
*  Given:
*     DJM      dp     modified Julian Date (JD-2400000.5)
*
*  Returned:
*     IY       int    year
*     IM       int    month
*     ID       int    day
*     FD       dp     fraction of day
*     J        int    status:
*                       0 = OK
*                      -1 = unacceptable date (before 4701BC March 1)
*
*  The algorithm is adapted from Hatcher 1984 (QJRAS 25, 53-55).
*
*  Last revision:   22 July 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., 59 Temple Place, Suite 330, 
*    Boston, MA  02111-1307  USA
*
*-

      IMPLICIT NONE

      DOUBLE PRECISION DJM
      INTEGER IY,IM,ID
      DOUBLE PRECISION FD
      INTEGER J

      DOUBLE PRECISION F,D
      INTEGER JD,N4,ND10


*  Check if date is acceptable.
      IF ( DJM.LE.-2395520D0 .OR. DJM.GE.1D9 ) THEN
         J = -1
      ELSE
         J = 0

*     Separate day and fraction.
         F = MOD(DJM,1D0)
         IF (F.LT.0D0) F = F+1D0
         D = ANINT(DJM-F)

*     Express day in Gregorian calendar.
         JD = NINT(D)+2400001

         N4 = 4*(JD+((6*((4*JD-17918)/146097))/4+1)/2-37)
         ND10 = 10*(MOD(N4-237,1461)/4)+5

         IY = N4/1461-4712
         IM = MOD(ND10/306+2,12)+1
         ID = MOD(ND10,306)/10+1
         FD = F

         J=0

      END IF

      END