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Diffstat (limited to 'ast/erfa/pn06.c')
-rw-r--r-- | ast/erfa/pn06.c | 196 |
1 files changed, 196 insertions, 0 deletions
diff --git a/ast/erfa/pn06.c b/ast/erfa/pn06.c new file mode 100644 index 0000000..63cf117 --- /dev/null +++ b/ast/erfa/pn06.c @@ -0,0 +1,196 @@ +#include "erfa.h" + +void eraPn06(double date1, double date2, double dpsi, double deps, + double *epsa, + double rb[3][3], double rp[3][3], double rbp[3][3], + double rn[3][3], double rbpn[3][3]) +/* +** - - - - - - - - +** e r a P n 0 6 +** - - - - - - - - +** +** Precession-nutation, IAU 2006 model: a multi-purpose function, +** supporting classical (equinox-based) use directly and CIO-based use +** indirectly. +** +** Given: +** date1,date2 double TT as a 2-part Julian Date (Note 1) +** dpsi,deps double nutation (Note 2) +** +** Returned: +** epsa double mean obliquity (Note 3) +** rb double[3][3] frame bias matrix (Note 4) +** rp double[3][3] precession matrix (Note 5) +** rbp double[3][3] bias-precession matrix (Note 6) +** rn double[3][3] nutation matrix (Note 7) +** rbpn double[3][3] GCRS-to-true matrix (Note 8) +** +** Notes: +** +** 1) The TT date date1+date2 is a Julian Date, apportioned in any +** convenient way between the two arguments. For example, +** JD(TT)=2450123.7 could be expressed in any of these ways, +** among others: +** +** date1 date2 +** +** 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) +** +** The JD method is the most natural and convenient to use in +** cases where the loss of several decimal digits of resolution +** is acceptable. The J2000 method is best matched to the way +** the argument is handled internally and will deliver the +** optimum resolution. The MJD method and the date & time methods +** are both good compromises between resolution and convenience. +** +** 2) The caller is responsible for providing the nutation components; +** they are in longitude and obliquity, in radians and are with +** respect to the equinox and ecliptic of date. For high-accuracy +** applications, free core nutation should be included as well as +** any other relevant corrections to the position of the CIP. +** +** 3) The returned mean obliquity is consistent with the IAU 2006 +** precession. +** +** 4) The matrix rb transforms vectors from GCRS to J2000.0 mean +** equator and equinox by applying frame bias. +** +** 5) The matrix rp transforms vectors from J2000.0 mean equator and +** equinox to mean equator and equinox of date by applying +** precession. +** +** 6) The matrix rbp transforms vectors from GCRS to mean equator and +** equinox of date by applying frame bias then precession. It is +** the product rp x rb. +** +** 7) The matrix rn transforms vectors from mean equator and equinox +** of date to true equator and equinox of date by applying the +** nutation (luni-solar + planetary). +** +** 8) The matrix rbpn transforms vectors from GCRS to true equator and +** equinox of date. It is the product rn x rbp, applying frame +** bias, precession and nutation in that order. +** +** 9) The X,Y,Z coordinates of the Celestial Intermediate Pole are +** elements (3,1-3) of the GCRS-to-true matrix, i.e. rbpn[2][0-2]. +** +** 10) It is permissible to re-use the same array in the returned +** arguments. The arrays are filled in the stated order. +** +** Called: +** eraPfw06 bias-precession F-W angles, IAU 2006 +** eraFw2m F-W angles to r-matrix +** eraCr copy r-matrix +** eraTr transpose r-matrix +** eraRxr product of two r-matrices +** +** References: +** +** Capitaine, N. & Wallace, P.T., 2006, Astron.Astrophys. 450, 855 +** +** Wallace, P.T. & Capitaine, N., 2006, Astron.Astrophys. 459, 981 +** +** Copyright (C) 2013-2016, NumFOCUS Foundation. +** Derived, with permission, from the SOFA library. See notes at end of file. +*/ +{ + double gamb, phib, psib, eps, r1[3][3], r2[3][3], rt[3][3]; + + +/* Bias-precession Fukushima-Williams angles of J2000.0 = frame bias. */ + eraPfw06(ERFA_DJM0, ERFA_DJM00, &gamb, &phib, &psib, &eps); + +/* B matrix. */ + eraFw2m(gamb, phib, psib, eps, r1); + eraCr(r1, rb); + +/* Bias-precession Fukushima-Williams angles of date. */ + eraPfw06(date1, date2, &gamb, &phib, &psib, &eps); + +/* Bias-precession matrix. */ + eraFw2m(gamb, phib, psib, eps, r2); + eraCr(r2, rbp); + +/* Solve for precession matrix. */ + eraTr(r1, rt); + eraRxr(r2, rt, rp); + +/* Equinox-based bias-precession-nutation matrix. */ + eraFw2m(gamb, phib, psib + dpsi, eps + deps, r1); + eraCr(r1, rbpn); + +/* Solve for nutation matrix. */ + eraTr(r2, rt); + eraRxr(r1, rt, rn); + +/* Obliquity, mean of date. */ + *epsa = eps; + + return; + +} +/*---------------------------------------------------------------------- +** +** +** 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. +** +*/ |