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slalib/calyd.f

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+      SUBROUTINE sla_CALYD (IY, IM, ID, NY, ND, J)
+*+
+*     - - - - - -
+*      C A L Y D
+*     - - - - - -
+*
+*  Gregorian calendar date to year and day in year (in a Julian
+*  calendar aligned to the 20th/21st century Gregorian calendar).
+*
+*  (Includes century default feature:  use sla_CLYD for years
+*   before 100AD.)
+*
+*  Given:
+*     IY,IM,ID   int    year, month, day in Gregorian calendar
+*                       (year may optionally omit the century)
+*  Returned:
+*     NY         int    year (re-aligned Julian calendar)
+*     ND         int    day in year (1 = January 1st)
+*     J          int    status:
+*                         0 = OK
+*                         1 = bad year (before -4711)
+*                         2 = bad month
+*                         3 = bad day (but conversion performed)
+*
+*  Notes:
+*
+*  1  This routine exists to support the low-precision routines
+*     sla_EARTH, sla_MOON and sla_ECOR.
+*
+*  2  Between 1900 March 1 and 2100 February 28 it returns answers
+*     which are consistent with the ordinary Gregorian calendar.
+*     Outside this range there will be a discrepancy which increases
+*     by one day for every non-leap century year.
+*
+*  3  Years in the range 50-99 are interpreted as 1950-1999, and
+*     years in the range 00-49 are interpreted as 2000-2049.
+*
+*  Called:  sla_CLYD
+*
+*  P.T.Wallace   Starlink   23 November 1994
+*
+*  Copyright (C) 1995 Rutherford Appleton Laboratory
+*
+*  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
+
+      INTEGER IY,IM,ID,NY,ND,J
+
+      INTEGER I
+
+
+
+*  Default century if appropriate
+      IF (IY.GE.0.AND.IY.LE.49) THEN
+         I=IY+2000
+      ELSE IF (IY.GE.50.AND.IY.LE.99) THEN
+         I=IY+1900
+      ELSE
+         I=IY
+      END IF
+
+*  Perform the conversion
+      CALL sla_CLYD(I,IM,ID,NY,ND,J)
+
+      END