summaryrefslogtreecommitdiffstats
path: root/ast/erfa/ee00b.c
diff options
context:
space:
mode:
authorWilliam Joye <wjoye@cfa.harvard.edu>2016-11-02 19:16:17 (GMT)
committerWilliam Joye <wjoye@cfa.harvard.edu>2016-11-02 19:16:17 (GMT)
commit293057bdd882685f8ddad66bf77196a5853b08da (patch)
tree22c02c3808f490432f5f785c8bb665438169662b /ast/erfa/ee00b.c
parent87f20cbc44f8f6b53c00c37f89bc134a1f4cf29e (diff)
parentd26ed8388f100a12996c0b92a98040ef2ba7fa8e (diff)
downloadblt-293057bdd882685f8ddad66bf77196a5853b08da.zip
blt-293057bdd882685f8ddad66bf77196a5853b08da.tar.gz
blt-293057bdd882685f8ddad66bf77196a5853b08da.tar.bz2
Merge commit 'd26ed8388f100a12996c0b92a98040ef2ba7fa8e' as 'ast'
Diffstat (limited to 'ast/erfa/ee00b.c')
-rw-r--r--ast/erfa/ee00b.c150
1 files changed, 150 insertions, 0 deletions
diff --git a/ast/erfa/ee00b.c b/ast/erfa/ee00b.c
new file mode 100644
index 0000000..2bed962
--- /dev/null
+++ b/ast/erfa/ee00b.c
@@ -0,0 +1,150 @@
+#include "erfa.h"
+
+double eraEe00b(double date1, double date2)
+/*
+** - - - - - - - - -
+** e r a E e 0 0 b
+** - - - - - - - - -
+**
+** Equation of the equinoxes, compatible with IAU 2000 resolutions but
+** using the truncated nutation model IAU 2000B.
+**
+** Given:
+** date1,date2 double TT as a 2-part Julian Date (Note 1)
+**
+** Returned (function value):
+** double equation of the equinoxes (Note 2)
+**
+** 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 result, which is in radians, operates in the following sense:
+**
+** Greenwich apparent ST = GMST + equation of the equinoxes
+**
+** 3) The result is compatible with the IAU 2000 resolutions except
+** that accuracy has been compromised for the sake of speed. For
+** further details, see McCarthy & Luzum (2001), IERS Conventions
+** 2003 and Capitaine et al. (2003).
+**
+** Called:
+** eraPr00 IAU 2000 precession adjustments
+** eraObl80 mean obliquity, IAU 1980
+** eraNut00b nutation, IAU 2000B
+** eraEe00 equation of the equinoxes, IAU 2000
+**
+** References:
+**
+** Capitaine, N., Wallace, P.T. and McCarthy, D.D., "Expressions to
+** implement the IAU 2000 definition of UT1", Astronomy &
+** Astrophysics, 406, 1135-1149 (2003)
+**
+** McCarthy, D.D. & Luzum, B.J., "An abridged model of the
+** precession-nutation of the celestial pole", Celestial Mechanics &
+** Dynamical Astronomy, 85, 37-49 (2003)
+**
+** McCarthy, D. D., Petit, G. (eds.), IERS Conventions (2003),
+** IERS Technical Note No. 32, BKG (2004)
+**
+** Copyright (C) 2013-2016, NumFOCUS Foundation.
+** Derived, with permission, from the SOFA library. See notes at end of file.
+*/
+{
+ double dpsipr, depspr, epsa, dpsi, deps, ee;
+
+
+/* IAU 2000 precession-rate adjustments. */
+ eraPr00(date1, date2, &dpsipr, &depspr);
+
+/* Mean obliquity, consistent with IAU 2000 precession-nutation. */
+ epsa = eraObl80(date1, date2) + depspr;
+
+/* Nutation in longitude. */
+ eraNut00b(date1, date2, &dpsi, &deps);
+
+/* Equation of the equinoxes. */
+ ee = eraEe00(date1, date2, epsa, dpsi);
+
+ return ee;
+
+}
+/*----------------------------------------------------------------------
+**
+**
+** 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.
+**
+*/