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# jd2cal

erfa.jd2cal(dj1, dj2)

  Julian Date to Gregorian year, month, day, and fraction of a day.

  Parameters
    dj1 double array
    dj2 double array
  Returns
    iy int array
    im int array
    id int array
    fd double array

  Notes

  Wraps ERFA function `eraJd2cal`. The ERFA documentation is:

      - - - - - - - - - -
       e r a J d 2 c a l
      - - - - - - - - - -

      Julian Date to Gregorian year, month, day, and fraction of a day.

      Given:
         dj1,dj2   double   Julian Date (Notes 1, 2)

      Returned (arguments):
         iy        int      year
         im        int      month
         id        int      day
         fd        double   fraction of day

      Returned (function value):
                   int      status:
                               0 = OK
                              -1 = unacceptable date (Note 1)

      Notes:

      1) The earliest valid date is -68569.5 (-4900 March 1).  The
         largest value accepted is 1e9.

      2) The Julian Date is apportioned in any convenient way between
         the arguments dj1 and dj2.  For example, JD=2450123.7 could
         be expressed in any of these ways, among others:

                dj1             dj2

             2450123.7           0.0       (JD method)
             2451545.0       -1421.3       (J2000 method)
             2400000.5       50123.2       (MJD method)
             2450123.5           0.2       (date & time method)

         Separating integer and fraction uses the "compensated summation"
         algorithm of Kahan-Neumaier to preserve as much precision as
         possible irrespective of the jd1+jd2 apportionment.

      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.

      References:

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

         Klein, A., A Generalized Kahan-Babuska-Summation-Algorithm.
         Computing, 76, 279-293 (2006), Section 3.

      This revision:  2021 May 11

      Copyright (C) 2013-2021, NumFOCUS Foundation.
      Derived, with permission, from the SOFA library.  See notes at end of file.