NAME:
       YMD2JD
 PURPOSE:
       From Year, Month, and Day compute Julian Day number.
 CATEGORY:
 CALLING SEQUENCE:
       jd = ymd2jd(y,m,d)
 INPUTS:
       y = Year (like 1987).                    in
       m = month (like 7 for July).             in
       d = month day (like 23).                 in
 KEYWORD PARAMETERS:
 OUTPUTS:
       jd = Julian Day number (like 2447000).   out
 CALLED BY:
	JD2YMD [1], JD2YMD [2], JD2YMD [3], SUN [1], SUN [2], WEEKDAY [1], WEEKDAY [2]
	WEEKDAY [3]
 COMMON BLOCKS:
 NOTES:
 MODIFICATION HISTORY:
       R. Sterner,  23 June, 1985 --- converted from FORTRAN.
       Johns Hopkins University Applied Physics Laboratory.
       RES 18 Sep, 1989 --- converted to SUN

 Copyright (C) 1985, Johns Hopkins University/Applied Physics Laboratory
 This software may be used, copied, or redistributed as long as it is not
 sold and this copyright notice is reproduced on each copy made.  This
 routine is provided as is without any express or implied warranties
 whatsoever.  Other limitations apply as described in the file disclaimer.txt.