C $Header: /home/ubuntu/mnt/e9_copy/MITgcm/pkg/cal/cal_toseconds.F,v 1.6 2003/12/18 06:20:53 dimitri Exp $
C $Name:  $

#include "CAL_OPTIONS.h"

      subroutine cal_ToSeconds(
     I                          date,
     O                          timeint,
     I                          mythid
     &                        )

c     ==================================================================
c     SUBROUTINE cal_ToSeconds
c     ==================================================================
c
c     o Given a time interval as a date array return the number of
c       seconds in that time interval.
c
c       If one wanted to use calendar dates in this routine, then
c       the date should be after the calendar's refdate and timeint
c       would be the number of seconds that have elapsed since the
c       refdate. Of course this can also be done by first calling
c       sub cal_TimePassed and then calling this routine with the
c       resulting time interval array.
c              
c     started: Christian Eckert eckert@mit.edu  30-Jun-1999
c
c     changed: Christian Eckert eckert@mit.edu  29-Dec-1999
c
c              - restructured the original version in order to have a
c                better interface to the MITgcmUV.
c
c              Christian Eckert eckert@mit.edu  03-Feb-2000
c
c              - Introduced new routine and function names, cal_<NAME>,
c                for verion 0.1.3.
c
c              21-Sep-2003: fixed check_sign logic to work with
c              negative intervals (menemenlis@jpl.nasa.gov)
c
c     ==================================================================
c     SUBROUTINE cal_ToSeconds
c     ==================================================================

      implicit none

c     == global variables ==

#include "cal.h"

c     == routine arguments ==

      integer date(4)
      _RL     timeint
      integer mythid

c     == local variables ==

      _RL     fac, nsecs, ndays, hhmmss
      integer ierr, check_sign

c     == end of interface ==
c     print *,'cal_toseconds: date',date
c     print *,'cal_toseconds: timeint',timeint

      check_sign = 1
      if ( ( (date(1).lt.0) .and. date(2).gt.0 ) .or.
     &     ( (date(1).gt.0) .and. date(2).lt.0 ) )
     &     check_sign = -1

      if (((date(4) .eq. -1) .and.
     &    (date(3) .eq.  0) .and.
     &    (check_sign .ge. 0)) .or.
     &    usingModelCalendar) then
        if ((date(1) .lt. 0) .or.
     &      (date(2) .lt. 0)) then
          ndays  = -date(1)
          hhmmss = -date(2)
          fac    = -1
        else
          ndays  = date(1)
          hhmmss = date(2)
          fac    = 1
        endif
        nsecs   = ndays*secondsperday +
     &            (hhmmss/10000)*secondsperhour +
     &            mod(hhmmss/100,100)*secondsperminute +
     &            mod(hhmmss,100)
        timeint = fac*nsecs
      else

        ierr = 1001
        call cal_PrintError( ierr, mythid )
        stop ' stopped in cal_ToSeconds.'

      endif

      return
      end