integer function finddate ( indate, flag, dates, xdates, ndates )
C
C	searchs for a date in an array of dates. The format of the
C	dates in both the array and the date is for example,
C
C		23-DEC-1992 09:47:56.1234
C	
C	return value = index of latest date in array just prior to indate
C	retrun = -1 if indate preceds dates[1]
C
C	assumptions: 
C		1) ndates > 1
C		2) the array is time ordered.
C
C	name    type dimension 	description
C	------- ---- ---------- ---------------------------
C	indate  c*25 1		date to find in array dates
C       flag    logical         .true. use dates
C				.false. use xdates
C	dates   c*25 ndates	array of dates
C       xdates  D.P. ndates     same, in DP ch2sec output format
C	ndates  i    1          size of array dates
C
        integer idate
        data idate/-1/
        integer ndates, i1, i2, imid
	character*25 dates(ndates), sec2ch
	double precision ch2sec, tin, tcheck, it1, it2, itmid
	double precision xdates(ndates)
	external ch2sec
        logical error, flag

        tin = ch2sec ( indate, .true., error) 
        
        i1 = 1
        i2 = ndates

	if (flag) then
          it1 = ch2sec ( dates(i1), .true., error)
          it2 = ch2sec ( dates(i2), .true., error)
        else
	  it1 = xdates(i1)
          it2 = xdates(i2)
	end if

C
C	check for date out of range of array
C	

	if (tin .lt. it1 ) then
	     idate = -1
	     goto 9999
        else if (tin .ge. it2 ) then
	     idate = ndates
             goto 9999
	end if
C
C	at this point, know that
C
C	  dates(1) <= indate < dates(ndate)
C
C	check for only 2 points
C
	if ( ndates .eq. 2 ) then
	   idate = 1
	   goto 9999
	end if
C
C	there are at least 3 points in the array. Narrow it down.
C
        do while ( (i2-i1) .gt. 1)
	   imid = (i2+i1)/2
	   if (flag) then
	     itmid = ch2sec ( dates(imid), .true., error)
	   else
	     itmid = xdates(imid)
	   end if

           if  (tin .lt. itmid) then
	      i2  = imid
	   else
	      i1 = imid
	   end if
	end do
        idate = i1
C
C	check for repeated time code
C
     
 8888   continue

	i3 = idate+1
        if (i3 .gt. ndates) goto 9999

	if (flag) then
           itmid = ch2sec ( dates(i3), .true., error)
	else
	   itmid = xdates (i3)
	end if
	if (itmid .lt. tin) then
	      idate = i3
              goto 8888
	end if

 9999   continue
        finddate = idate
	return
	end


C        program tester
C        integer finddate
C        character*25 dates(11), indate
C	data dates / '16-APR-1992 23:30',
C     &	'19-APR-1992 15:12', '13-MAY-1992 01:48', '18-JUN-1992 22:20',
C     &  '27-JUL-1992 14:20', '29-AUG-1993 15:03', '2-SEP-1993 03:01',
C     &  '6-OCT-1993 04:27', '11-NOV-1993 19:22', '12-DEC-1993 08:29',
C     &  '13-MAY-1994 05:06'/
C	write(6,*) dates
C 50     write(6,*) '***'
C	write(6,*) 'Enter date:'
C	read(6,100) indate
C 100    format (A25)
C        idate = finddate(indate, dates, 11)
C	write(6,*) 'idate = ', idate, ' ',dates(idate)
C	if (.true.) goto 50
C	stop
C	end