FUNCTION DELDAY(ID1,ID2)
c
c	y2k version: modified, July 1998, hpf
c	Looking at original delday code, it didn't seem that the century number
c	even need to be specified, but since it was, I added mods for y2k.
c	2 digit years < 50 will have 2000 added, 
c	if >/= 50, will have 1900 added.
C
C     COMPUTES NUMBER OF DAYS BETWEEN TWO POINTS IN TIME
C
C     PROGRAMMED BY PAUL FREITAG JUNE 76  
C
      DIMENSION NDAY(12),ID1(5),ID2(5)
      DATA NDAY /31,28,31,30,31,30,31,31,30,31,30,31/
	real*8 dd1,dd2
C      IHR1=ID1(1)
C      IMIN1=ID1(2)
C      IDY1=ID1(3)
C      IMTH1=ID1(4)
C      IYR1=ID1(5)
C      IHR2=ID2(1)
C      IMIN2=ID2(2)
C      IDY2=ID2(3)
C      IMTH2=ID2(4)
C      IYR2=ID2(5) 
	if(id1(5).gt.100) then
	icen1=0
	elseif (id1(5).ge.50) then
	icen1=1900
	elseif (id1(5).lt.50) then
	icen1=2000
	endif
	if(id2(5).gt.100) then
	icen2=0
	elseif (id2(5).ge.50) then
	icen2=1900
	elseif (id2(5).lt.50) then
	icen2=2000
	endif
c	print*, icen1,icen2
      NDAY(2)=28
      IF (MOD(ID1(5)+icen1,4).EQ.0) NDAY(2)=29
      DD1=0.0
      NM1=ID1(4)-1
      IF (NM1.EQ.0) GO TO 15
      DO 10 I=1,NM1 
      DD=NDAY(I)
   10 DD1=DD1+DD
   15 DD1=DD1+FLOAT(ID1(3))+(FLOAT(ID1(1)))/24.+(FLOAT(ID1(2)))/1440.-1. 
      DD2=0.0
      NDYR=ID2(5)+icen2-ID1(5)-icen1
      IF (NDYR) 16,40,20
16	ndyr=-ndyr
	DO 18 I=1,NDYR  
      DPR=365.
      IF (MOD(icen1+ID1(5)-I,4).EQ.0) DPR=366.
18	DD1=DD1+DPR
	go to 40
   20 DO 30 I=1,NDYR  
      DPR=365.
      IF (MOD(icen1-1+ID1(5)+I,4).EQ.0) DPR=366.
   30 DD2=DD2+DPR
   40 NM2=ID2(4)-1
      IF (NM2.EQ.0) GO TO 55
      NDAY(2)=28
      IF (MOD(ID2(5)+icen2,4).EQ.0) NDAY(2)=29
      DO 50 I=1,NM2 
      DD=NDAY(I)
   50 DD2=DD2+DD
   55 DD2=DD2+FLOAT(ID2(3))+(FLOAT(ID2(1)))/24.+(FLOAT(ID2(2)))/1440.-1. 
      DELDAY=DD2-DD1
      RETURN
      END