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.help clyd Jun99 "Slalib Package"
.nf
SUBROUTINE slCLYD (IY, IM, ID, NY, ND, JSTAT)
- - - - -
C L Y D
- - - - -
Gregorian calendar to year and day in year (in a Julian calendar
aligned to the 20th/21st century Gregorian calendar).
Given:
IY,IM,ID i year, month, day in Gregorian calendar
Returned:
NY i year (re-aligned Julian calendar)
ND i day in year (1 = January 1st)
JSTAT i status:
0 = OK
1 = bad year (before -4711)
2 = bad month
3 = bad day (but conversion performed)
Notes:
1 This routine exists to support the low-precision routines
slERTH, slMOON and slECOR.
2 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.
3 The essence of the algorithm is first to express the Gregorian
date as a Julian Day Number and then to convert this back to
a Julian calendar date, with day-in-year instead of month and
day. See 12.92-1 and 12.95-1 in the reference.
Reference: Explanatory Supplement to the Astronomical Almanac,
ed P.K.Seidelmann, University Science Books (1992),
p604-606.
P.T.Wallace Starlink 26 November 1994
Copyright (C) 1995 Rutherford Appleton Laboratory
Copyright (C) 1995 Association of Universities for Research in Astronomy Inc.
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.endhelp
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