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#include "erfa.h"
int eraJd2cal(double dj1, double dj2,
int *iy, int *im, int *id, double *fd)
/*
** - - - - - - - - - -
** 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 3)
**
** 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)
**
** 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).
**
** Copyright (C) 2013-2016, NumFOCUS Foundation.
** Derived, with permission, from the SOFA library. See notes at end of file.
*/
{
/* Minimum and maximum allowed JD */
const double DJMIN = -68569.5;
const double DJMAX = 1e9;
long jd, l, n, i, k;
double dj, d1, d2, f1, f2, f, d;
/* Verify date is acceptable. */
dj = dj1 + dj2;
if (dj < DJMIN || dj > DJMAX) return -1;
/* Copy the date, big then small, and re-align to midnight. */
if (dj1 >= dj2) {
d1 = dj1;
d2 = dj2;
} else {
d1 = dj2;
d2 = dj1;
}
d2 -= 0.5;
/* Separate day and fraction. */
f1 = fmod(d1, 1.0);
f2 = fmod(d2, 1.0);
f = fmod(f1 + f2, 1.0);
if (f < 0.0) f += 1.0;
d = floor(d1 - f1) + floor(d2 - f2) + floor(f1 + f2 - f);
jd = (long) floor(d) + 1L;
/* Express day in Gregorian calendar. */
l = jd + 68569L;
n = (4L * l) / 146097L;
l -= (146097L * n + 3L) / 4L;
i = (4000L * (l + 1L)) / 1461001L;
l -= (1461L * i) / 4L - 31L;
k = (80L * l) / 2447L;
*id = (int) (l - (2447L * k) / 80L);
l = k / 11L;
*im = (int) (k + 2L - 12L * l);
*iy = (int) (100L * (n - 49L) + i + l);
*fd = f;
return 0;
}
/*----------------------------------------------------------------------
**
**
** Copyright (C) 2013-2016, NumFOCUS Foundation.
** All rights reserved.
**
** This library is derived, with permission, from the International
** Astronomical Union's "Standards of Fundamental Astronomy" library,
** available from http://www.iausofa.org.
**
** The ERFA version is intended to retain identical functionality to
** the SOFA library, but made distinct through different function and
** file names, as set out in the SOFA license conditions. The SOFA
** original has a role as a reference standard for the IAU and IERS,
** and consequently redistribution is permitted only in its unaltered
** state. The ERFA version is not subject to this restriction and
** therefore can be included in distributions which do not support the
** concept of "read only" software.
**
** Although the intent is to replicate the SOFA API (other than
** replacement of prefix names) and results (with the exception of
** bugs; any that are discovered will be fixed), SOFA is not
** responsible for any errors found in this version of the library.
**
** If you wish to acknowledge the SOFA heritage, please acknowledge
** that you are using a library derived from SOFA, rather than SOFA
** itself.
**
**
** TERMS AND CONDITIONS
**
** Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions
** are met:
**
** 1 Redistributions of source code must retain the above copyright
** notice, this list of conditions and the following disclaimer.
**
** 2 Redistributions in binary form must reproduce the above copyright
** notice, this list of conditions and the following disclaimer in
** the documentation and/or other materials provided with the
** distribution.
**
** 3 Neither the name of the Standards Of Fundamental Astronomy Board,
** the International Astronomical Union nor the names of its
** contributors may be used to endorse or promote products derived
** from this software without specific prior written permission.
**
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
** ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
** POSSIBILITY OF SUCH DAMAGE.
**
*/
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