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Diffstat (limited to 'ast/erfa/jdcalf.c')
| -rw-r--r-- | ast/erfa/jdcalf.c | 170 |
1 files changed, 170 insertions, 0 deletions
diff --git a/ast/erfa/jdcalf.c b/ast/erfa/jdcalf.c new file mode 100644 index 0000000..3bd54ab --- /dev/null +++ b/ast/erfa/jdcalf.c @@ -0,0 +1,170 @@ +#include "erfa.h" + +int eraJdcalf(int ndp, double dj1, double dj2, int iymdf[4]) +/* +** - - - - - - - - - - +** e r a J d c a l f +** - - - - - - - - - - +** +** Julian Date to Gregorian Calendar, expressed in a form convenient +** for formatting messages: rounded to a specified precision. +** +** Given: +** ndp int number of decimal places of days in fraction +** dj1,dj2 double dj1+dj2 = Julian Date (Note 1) +** +** Returned: +** iymdf int[4] year, month, day, fraction in Gregorian +** calendar +** +** Returned (function value): +** int status: +** -1 = date out of range +** 0 = OK +** +1 = NDP not 0-9 (interpreted as 0) +** +** Notes: +** +** 1) 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) +** +** 2) 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. +** +** 3) Refer to the function eraJd2cal. +** +** 4) NDP should be 4 or less if internal overflows are to be +** avoided on machines which use 16-bit integers. +** +** Called: +** eraJd2cal JD to Gregorian calendar +** +** Reference: +** +** Explanatory Supplement to the Astronomical Almanac, +** P. Kenneth Seidelmann (ed), University Science Books (1992), +** Section 12.92 (p604). +** +** Copyright (C) 2013-2014, NumFOCUS Foundation. +** Derived, with permission, from the SOFA library. See notes at end of file. +*/ +{ + int j, js; + double denom, d1, d2, f1, f2, f; + + +/* Denominator of fraction (e.g. 100 for 2 decimal places). */ + if ((ndp >= 0) && (ndp <= 9)) { + j = 0; + denom = pow(10.0, ndp); + } else { + j = 1; + denom = 1.0; + } + +/* Copy the date, big then small, and realign to midnight. */ + if (dj1 >= dj2) { + d1 = dj1; + d2 = dj2; + } else { + d1 = dj2; + d2 = dj1; + } + d2 -= 0.5; + +/* Separate days and fractions. */ + f1 = fmod(d1, 1.0); + f2 = fmod(d2, 1.0); + d1 = floor(d1 - f1); + d2 = floor(d2 - f2); + +/* Round the total fraction to the specified number of places. */ + f = floor((f1+f2)*denom + 0.5) / denom; + +/* Re-assemble the rounded date and re-align to noon. */ + d2 += f + 0.5; + +/* Convert to Gregorian calendar. */ + js = eraJd2cal(d1, d2, &iymdf[0], &iymdf[1], &iymdf[2], &f); + if (js == 0) { + iymdf[3] = (int) (f * denom); + } else { + j = js; + } + +/* Return the status. */ + return j; + +} +/*---------------------------------------------------------------------- +** +** +** Copyright (C) 2013-2014, 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. +** +*/ |