diff options
author | William Joye <wjoye@cfa.harvard.edu> | 2016-10-17 15:22:52 (GMT) |
---|---|---|
committer | William Joye <wjoye@cfa.harvard.edu> | 2016-10-17 15:22:52 (GMT) |
commit | 7dd9b970cec6832b8f6118dc2dd91a08d2836648 (patch) | |
tree | 4b3c86596ab87f35a3c6213397da07afe1e24d3e /ast/erfa/c2ibpn.c | |
parent | d7bf7c61e8507e3cf51f195392c0f41f27ae18d8 (diff) | |
parent | 7fde2daeed593684120d75de07598154f3ddaf2c (diff) | |
download | blt-7dd9b970cec6832b8f6118dc2dd91a08d2836648.zip blt-7dd9b970cec6832b8f6118dc2dd91a08d2836648.tar.gz blt-7dd9b970cec6832b8f6118dc2dd91a08d2836648.tar.bz2 |
Merge commit '7fde2daeed593684120d75de07598154f3ddaf2c' as 'ast'
Diffstat (limited to 'ast/erfa/c2ibpn.c')
-rw-r--r-- | ast/erfa/c2ibpn.c | 151 |
1 files changed, 151 insertions, 0 deletions
diff --git a/ast/erfa/c2ibpn.c b/ast/erfa/c2ibpn.c new file mode 100644 index 0000000..74cd10b --- /dev/null +++ b/ast/erfa/c2ibpn.c @@ -0,0 +1,151 @@ +#include "erfa.h" + +void eraC2ibpn(double date1, double date2, double rbpn[3][3], + double rc2i[3][3]) +/* +** - - - - - - - - - - +** e r a C 2 i b p n +** - - - - - - - - - - +** +** Form the celestial-to-intermediate matrix for a given date given +** the bias-precession-nutation matrix. IAU 2000. +** +** Given: +** date1,date2 double TT as a 2-part Julian Date (Note 1) +** rbpn double[3][3] celestial-to-true matrix (Note 2) +** +** Returned: +** rc2i double[3][3] celestial-to-intermediate matrix (Note 3) +** +** 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 matrix rbpn transforms vectors from GCRS to true equator (and +** CIO or equinox) of date. Only the CIP (bottom row) is used. +** +** 3) The matrix rc2i is the first stage in the transformation from +** celestial to terrestrial coordinates: +** +** [TRS] = RPOM * R_3(ERA) * rc2i * [CRS] +** +** = RC2T * [CRS] +** +** where [CRS] is a vector in the Geocentric Celestial Reference +** System and [TRS] is a vector in the International Terrestrial +** Reference System (see IERS Conventions 2003), ERA is the Earth +** Rotation Angle and RPOM is the polar motion matrix. +** +** 4) Although its name does not include "00", This function is in fact +** specific to the IAU 2000 models. +** +** Called: +** eraBpn2xy extract CIP X,Y coordinates from NPB matrix +** eraC2ixy celestial-to-intermediate matrix, given X,Y +** +** References: +** "Expressions for the Celestial Intermediate Pole and Celestial +** Ephemeris Origin consistent with the IAU 2000A precession- +** nutation model", Astron.Astrophys. 400, 1145-1154 (2003) +** +** n.b. The celestial ephemeris origin (CEO) was renamed "celestial +** intermediate origin" (CIO) by IAU 2006 Resolution 2. +** +** McCarthy, D. D., Petit, G. (eds.), IERS Conventions (2003), +** IERS Technical Note No. 32, BKG (2004) +** +** Copyright (C) 2013-2014, NumFOCUS Foundation. +** Derived, with permission, from the SOFA library. See notes at end of file. +*/ +{ + double x, y; + + +/* Extract the X,Y coordinates. */ + eraBpn2xy(rbpn, &x, &y); + +/* Form the celestial-to-intermediate matrix (n.b. IAU 2000 specific). */ + eraC2ixy(date1, date2, x, y, rc2i); + + return; + +} +/*---------------------------------------------------------------------- +** +** +** 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. +** +*/ |