summaryrefslogtreecommitdiffstats
path: root/ast/erfa/fw2m.c
diff options
context:
space:
mode:
Diffstat (limited to 'ast/erfa/fw2m.c')
-rw-r--r--ast/erfa/fw2m.c143
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..d1b73d2
--- /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) 2013-2016, 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) 2013-2016, 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.
+**
+*/