### SLA_CALYD

Calendar to Year, Day

ACTION:
Gregorian calendar date to year and day in year, in a Julian calendar aligned to the 20th/21st century Gregorian calendar, with century default.
CALL:
CALL sla_CALYD (IY, IM, ID, NY, ND, J)
##### GIVEN:
 IY,IM,ID I year, month, day in Gregorian calendar: year may optionally omit the century

##### RETURNED:
 NY I year (re-aligned Julian calendar) ND I day in year (1 = January 1st) J I status: 0 = OK 1 = bad year (before $-4711$) 2 = bad month 3 = bad day

NOTES:
(1)
This routine supports the century default feature. Acceptable years are:
• 00-49, interpreted as 2000 – 2049,
• 50-99, interpreted as 1950 – 1999, and
• other years after $-4712$, interpreted literally.

Use sla_CLYD for years before 100AD.

(2)
The purpose of sla_CALDJ is to support sla_EARTH, sla_MOON and sla_ECOR.
(3)
Between 1900 March 1 and 2100 February 28 it returns answers which are consistent with the ordinary Gregorian calendar. Outside this range there will be a discrepancy which increases by one day for every non-leap century year.
(4)
When an invalid year or month is supplied (status J = 1 or J = 2) the results are not computed. When a day is supplied which is outside the conventional range (status J = 3) the results are computed.