real*8 function dyd( yd1, yd2 )
!
!     Returns the number of days (and fraction) between two real*8
!     dates of the form yyyyddd.dd.
!
!     B. Knapp, 96.04.11
!
C
C     RCS DATA
C     
C     $Header$
C     
C     $Log$
C
C
      implicit none
!
      real*8 yd1, yd2, jd1, jd2
!
!     Convert input dates to JD numbers, and subtract
      call yd2jd( yd1, jd1 )
      call yd2jd( yd2, jd2 )
      dyd = jd2-jd1
      return
      end