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 year, month, day in Gregorian calendar: year may optionally omit the century

RETURNED:

NY 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.