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Diffstat (limited to 'ast/erfa/fw2m.c')
| -rw-r--r-- | ast/erfa/fw2m.c | 143 |
1 files changed, 143 insertions, 0 deletions
diff --git a/ast/erfa/fw2m.c b/ast/erfa/fw2m.c new file mode 100644 index 0000000..a66bf22 --- /dev/null +++ b/ast/erfa/fw2m.c @@ -0,0 +1,143 @@ +#include "erfa.h" + +void eraFw2m(double gamb, double phib, double psi, double eps, + double r[3][3]) +/* +** - - - - - - - - +** e r a F w 2 m +** - - - - - - - - +** +** Form rotation matrix given the Fukushima-Williams angles. +** +** Given: +** gamb double F-W angle gamma_bar (radians) +** phib double F-W angle phi_bar (radians) +** psi double F-W angle psi (radians) +** eps double F-W angle epsilon (radians) +** +** Returned: +** r double[3][3] rotation matrix +** +** Notes: +** +** 1) Naming the following points: +** +** e = J2000.0 ecliptic pole, +** p = GCRS pole, +** E = ecliptic pole of date, +** and P = CIP, +** +** the four Fukushima-Williams angles are as follows: +** +** gamb = gamma = epE +** phib = phi = pE +** psi = psi = pEP +** eps = epsilon = EP +** +** 2) The matrix representing the combined effects of frame bias, +** precession and nutation is: +** +** NxPxB = R_1(-eps).R_3(-psi).R_1(phib).R_3(gamb) +** +** 3) Three different matrices can be constructed, depending on the +** supplied angles: +** +** o To obtain the nutation x precession x frame bias matrix, +** generate the four precession angles, generate the nutation +** components and add them to the psi_bar and epsilon_A angles, +** and call the present function. +** +** o To obtain the precession x frame bias matrix, generate the +** four precession angles and call the present function. +** +** o To obtain the frame bias matrix, generate the four precession +** angles for date J2000.0 and call the present function. +** +** The nutation-only and precession-only matrices can if necessary +** be obtained by combining these three appropriately. +** +** Called: +** eraIr initialize r-matrix to identity +** eraRz rotate around Z-axis +** eraRx rotate around X-axis +** +** Reference: +** +** Hilton, J. et al., 2006, Celest.Mech.Dyn.Astron. 94, 351 +** +** Copyright (C) 2013-2014, NumFOCUS Foundation. +** Derived, with permission, from the SOFA library. See notes at end of file. +*/ +{ +/* Construct the matrix. */ + eraIr(r); + eraRz(gamb, r); + eraRx(phib, r); + eraRz(-psi, r); + eraRx(-eps, r); + + 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. +** +*/ |