#include "sofa.h" int iauTcgtt(double tcg1, double tcg2, double *tt1, double *tt2) /* ** - - - - - - - - - ** i a u T c g t t ** - - - - - - - - - ** ** Time scale transformation: Geocentric Coordinate Time, TCG, to ** Terrestrial Time, TT. ** ** This function is part of the International Astronomical Union's ** SOFA (Standards of Fundamental Astronomy) software collection. ** ** Status: canonical. ** ** Given: ** tcg1,tcg2 double TCG as a 2-part Julian Date ** ** Returned: ** tt1,tt2 double TT as a 2-part Julian Date ** ** Returned (function value): ** int status: 0 = OK ** ** Note: ** ** tcg1+tcg2 is Julian Date, apportioned in any convenient way ** between the two arguments, for example where tcg1 is the Julian ** Day Number and tcg22 is the fraction of a day. The returned ** tt1,tt2 follow suit. ** ** References: ** ** McCarthy, D. D., Petit, G. (eds.), IERS Conventions (2003), ** IERS Technical Note No. 32, BKG (2004) ** ** IAU 2000 Resolution B1.9 ** ** This revision: 2020 October 23 ** ** SOFA release 2021-01-25 ** ** Copyright (C) 2021 IAU SOFA Board. See notes at end. */ { /* 1977 Jan 1 00:00:32.184 TT, as MJD */ static const double t77t = DJM77 + TTMTAI/DAYSEC; /* Result, safeguarding precision. */ if ( fabs(tcg1) > fabs(tcg2) ) { *tt1 = tcg1; *tt2 = tcg2 - ( ( tcg1 - DJM0 ) + ( tcg2 - t77t ) ) * ELG; } else { *tt1 = tcg1 - ( ( tcg2 - DJM0 ) + ( tcg1 - t77t ) ) * ELG; *tt2 = tcg2; } /* OK status. */ return 0; /*---------------------------------------------------------------------- ** ** Copyright (C) 2021 ** Standards Of Fundamental Astronomy Board ** of the International Astronomical Union. ** ** ===================== ** SOFA Software License ** ===================== ** ** NOTICE TO USER: ** ** BY USING THIS SOFTWARE YOU ACCEPT THE FOLLOWING SIX TERMS AND ** CONDITIONS WHICH APPLY TO ITS USE. ** ** 1. The Software is owned by the IAU SOFA Board ("SOFA"). ** ** 2. Permission is granted to anyone to use the SOFA software for any ** purpose, including commercial applications, free of charge and ** without payment of royalties, subject to the conditions and ** restrictions listed below. ** ** 3. You (the user) may copy and distribute SOFA source code to others, ** and use and adapt its code and algorithms in your own software, ** on a world-wide, royalty-free basis. That portion of your ** distribution that does not consist of intact and unchanged copies ** of SOFA source code files is a "derived work" that must comply ** with the following requirements: ** ** a) Your work shall be marked or carry a statement that it ** (i) uses routines and computations derived by you from ** software provided by SOFA under license to you; and ** (ii) does not itself constitute software provided by and/or ** endorsed by SOFA. ** ** b) The source code of your derived work must contain descriptions ** of how the derived work is based upon, contains and/or differs ** from the original SOFA software. ** ** c) The names of all routines in your derived work shall not ** include the prefix "iau" or "sofa" or trivial modifications ** thereof such as changes of case. ** ** d) The origin of the SOFA components of your derived work must ** not be misrepresented; you must not claim that you wrote the ** original software, nor file a patent application for SOFA ** software or algorithms embedded in the SOFA software. ** ** e) These requirements must be reproduced intact in any source ** distribution and shall apply to anyone to whom you have ** granted a further right to modify the source code of your ** derived work. ** ** Note that, as originally distributed, the SOFA software is ** intended to be a definitive implementation of the IAU standards, ** and consequently third-party modifications are discouraged. All ** variations, no matter how minor, must be explicitly marked as ** such, as explained above. ** ** 4. You shall not cause the SOFA software to be brought into ** disrepute, either by misuse, or use for inappropriate tasks, or ** by inappropriate modification. ** ** 5. The SOFA software is provided "as is" and SOFA makes no warranty ** as to its use or performance. SOFA does not and cannot warrant ** the performance or results which the user may obtain by using the ** SOFA software. SOFA makes no warranties, express or implied, as ** to non-infringement of third party rights, merchantability, or ** fitness for any particular purpose. In no event will SOFA be ** liable to the user for any consequential, incidental, or special ** damages, including any lost profits or lost savings, even if a ** SOFA representative has been advised of such damages, or for any ** claim by any third party. ** ** 6. The provision of any version of the SOFA software under the terms ** and conditions specified herein does not imply that future ** versions will also be made available under the same terms and ** conditions. * ** In any published work or commercial product which uses the SOFA ** software directly, acknowledgement (see www.iausofa.org) is ** appreciated. ** ** Correspondence concerning SOFA software should be addressed as ** follows: ** ** By email: sofa@ukho.gov.uk ** By post: IAU SOFA Center ** HM Nautical Almanac Office ** UK Hydrographic Office ** Admiralty Way, Taunton ** Somerset, TA1 2DN ** United Kingdom ** **--------------------------------------------------------------------*/ }