precession.h

/*
Copyright (C) 2015 Georg Zotti

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU Library General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Suite 500, Boston, MA  02110-1335, USA.
*/
#ifndef _PRECESSION_H_
#define _PRECESSION_H_

#ifdef __cplusplus
extern "C" {
#endif

void getPrecessionAnglesVondrak(const double jde, double *epsilon_A, double *chi_A, double *omega_A, double *psi_A);

void getPrecessionAnglesVondrakPQXYe(const double jde, double *vP_A, double *vQ_A, double *vX_A, double *vY_A, double *vepsilon_A);

double getPrecessionAngleVondrakEpsilon(const double jde);

double getPrecessionAngleVondrakCurrentEpsilonA(void);

// To complete the task of correct&accurate precession-nutation handling, we need fitting IAU-2000A or IAU-2000B Nutation.
// E.g. A&A 459, 981–985 (2006) P. T. Wallace and N. Capitaine: Precession-nutation procedures consistent with IAU 2006 resolutions. DOI: 10.1051/0004-6361:20065897
// IAU 2000A nutation has 1400 terms and goes into micro-arcseconds. All we ever aim for is sub-arcsecond, if at all, this is more than covered by IAU-2000B.

void getNutationAngles(const double JDE, double *deltaPsi, double *deltaEpsilon);

#ifdef __cplusplus
}
#endif

#endif