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eraCal2jd

[rv, djm0, djm] = ERFA.cal2jd(iy, im, id)

Gregorian Calendar to Julian Date.

Given:

   iy,im,id  int     year, month, day in Gregorian calendar (Note 1)

Returned:

   djm0      double  MJD zero-point: always 2400000.5
   djm       double  Modified Julian Date for 0 hrs

Returned (function value):

             int     status:
                         0 = OK
                        -1 = bad year   (Note 3: JD not computed)
                        -2 = bad month  (JD not computed)
                        -3 = bad day    (JD computed)

Notes:

  1. The algorithm used is valid from -4800 March 1, but this implementation rejects dates before -4799 January 1.

  2. The Julian Date is returned in two pieces, in the usual ERFA manner, which is designed to preserve time resolution. The Julian Date is available as a single number by adding djm0 and djm.

  3. In early eras the conversion is from the "Proleptic Gregorian Calendar"; no account is taken of the date(s) of adoption of the Gregorian Calendar, nor is the AD/BC numbering convention observed.

Reference:

Explanatory Supplement to the Astronomical Almanac, P. Kenneth Seidelmann (ed), University Science Books (1992), Section 12.92 (p604).

This revision: 2021 May 11

Copyright (C) 2013-2021, NumFOCUS Foundation. Derived, with permission, from the SOFA library.