Gregorian calendar to Modified Julian Date. (Includes century default feature: use slaCldj for years before 100AD.)
iy,im,id int year, month, day in Gregorian calendar
*djm double Modified Julian Date (JD-2400000.5) for 0 hrs
0 = ok 1 = bad year (MJD not computed) 2 = bad month (MJD not computed) 3 = bad day (MJD computed) Acceptable years are 00-49, interpreted as 2000-2049, 50-99, " " 1950-1999, 100 upwards, interpreted literally.
slaCldj P.T.Wallace Starlink 21 October 1993