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Diffstat (limited to 'ast/erfa/tdbtcb.c')
| -rw-r--r-- | ast/erfa/tdbtcb.c | 146 |
1 files changed, 0 insertions, 146 deletions
diff --git a/ast/erfa/tdbtcb.c b/ast/erfa/tdbtcb.c deleted file mode 100644 index c12f807..0000000 --- a/ast/erfa/tdbtcb.c +++ /dev/null @@ -1,146 +0,0 @@ -#include "erfa.h" - -int eraTdbtcb(double tdb1, double tdb2, double *tcb1, double *tcb2) -/* -** - - - - - - - - - - -** e r a T d b t c b -** - - - - - - - - - - -** -** Time scale transformation: Barycentric Dynamical Time, TDB, to -** Barycentric Coordinate Time, TCB. -** -** Given: -** tdb1,tdb2 double TDB as a 2-part Julian Date -** -** Returned: -** tcb1,tcb2 double TCB as a 2-part Julian Date -** -** Returned (function value): -** int status: 0 = OK -** -** Notes: -** -** 1) tdb1+tdb2 is Julian Date, apportioned in any convenient way -** between the two arguments, for example where tdb1 is the Julian -** Day Number and tdb2 is the fraction of a day. The returned -** tcb1,tcb2 follow suit. -** -** 2) The 2006 IAU General Assembly introduced a conventional linear -** transformation between TDB and TCB. This transformation -** compensates for the drift between TCB and terrestrial time TT, -** and keeps TDB approximately centered on TT. Because the -** relationship between TT and TCB depends on the adopted solar -** system ephemeris, the degree of alignment between TDB and TT over -** long intervals will vary according to which ephemeris is used. -** Former definitions of TDB attempted to avoid this problem by -** stipulating that TDB and TT should differ only by periodic -** effects. This is a good description of the nature of the -** relationship but eluded precise mathematical formulation. The -** conventional linear relationship adopted in 2006 sidestepped -** these difficulties whilst delivering a TDB that in practice was -** consistent with values before that date. -** -** 3) TDB is essentially the same as Teph, the time argument for the -** JPL solar system ephemerides. -** -** Reference: -** -** IAU 2006 Resolution B3 -** -** Copyright (C) 2013-2016, NumFOCUS Foundation. -** Derived, with permission, from the SOFA library. See notes at end of file. -*/ -{ - -/* 1977 Jan 1 00:00:32.184 TT, as two-part JD */ - static const double t77td = ERFA_DJM0 + ERFA_DJM77; - static const double t77tf = ERFA_TTMTAI/ERFA_DAYSEC; - -/* TDB (days) at TAI 1977 Jan 1.0 */ - static const double tdb0 = ERFA_TDB0/ERFA_DAYSEC; - -/* TDB to TCB rate */ - static const double elbb = ERFA_ELB/(1.0-ERFA_ELB); - - double d, f; - - -/* Result, preserving date format but safeguarding precision. */ - if ( tdb1 > tdb2 ) { - d = t77td - tdb1; - f = tdb2 - tdb0; - *tcb1 = tdb1; - *tcb2 = f - ( d - ( f - t77tf ) ) * elbb; - } else { - d = t77td - tdb2; - f = tdb1 - tdb0; - *tcb1 = f + ( d - ( f - t77tf ) ) * elbb; - *tcb2 = tdb2; - } - -/* Status (always OK). */ - 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. -** -*/ |