#include "erfa.h"
void eraPfw06(double date1, double date2,
double *gamb, double *phib, double *psib, double *epsa)
/*
** - - - - - - - - -
** e r a P f w 0 6
** - - - - - - - - -
**
** Precession angles, IAU 2006 (Fukushima-Williams 4-angle formulation).
**
** Given:
** date1,date2 double TT as a 2-part Julian Date (Note 1)
**
** Returned:
** gamb double F-W angle gamma_bar (radians)
** phib double F-W angle phi_bar (radians)
** psib double F-W angle psi_bar (radians)
** epsa double F-W angle epsilon_A (radians)
**
** 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) Naming the following points:
**
** e = J2000.0 ecliptic pole,
** p = GCRS pole,
** E = mean ecliptic pole of date,
** and P = mean pole of date,
**
** the four Fukushima-Williams angles are as follows:
**
** gamb = gamma_bar = epE
** phib = phi_bar = pE
** psib = psi_bar = pEP
** epsa = epsilon_A = EP
**
** 3) The matrix representing the combined effects of frame bias and
** precession is:
**
** PxB = R_1(-epsa).R_3(-psib).R_1(phib).R_3(gamb)
**
** 4) The matrix representing the combined effects of frame bias,
** precession and nutation is simply:
**
** NxPxB = R_1(-epsa-dE).R_3(-psib-dP).R_1(phib).R_3(gamb)
**
** where dP and dE are the nutation components with respect to the
** ecliptic of date.
**
** Reference:
**
** Hilton, J. et al., 2006, Celest.Mech.Dyn.Astron. 94, 351
**
** Called:
** eraObl06 mean obliquity, IAU 2006
**
** Copyright (C) 2013-2014, NumFOCUS Foundation.
** Derived, with permission, from the SOFA library. See notes at end of file.
*/
{
double t;
/* Interval between fundamental date J2000.0 and given date (JC). */
t = ((date1 - ERFA_DJ00) + date2) / ERFA_DJC;
/* P03 bias+precession angles. */
*gamb = ( -0.052928 +
( 10.556378 +
( 0.4932044 +
( -0.00031238 +
( -0.000002788 +
( 0.0000000260 )
* t) * t) * t) * t) * t) * ERFA_DAS2R;
*phib = ( 84381.412819 +
( -46.811016 +
( 0.0511268 +
( 0.00053289 +
( -0.000000440 +
( -0.0000000176 )
* t) * t) * t) * t) * t) * ERFA_DAS2R;
*psib = ( -0.041775 +
( 5038.481484 +
( 1.5584175 +
( -0.00018522 +
( -0.000026452 +
( -0.0000000148 )
* t) * t) * t) * t) * t) * ERFA_DAS2R;
*epsa = eraObl06(date1, date2);
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,
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** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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**
*/