/*
*+
* Name:
* palGeoc
* Purpose:
* Convert geodetic position to geocentric
* Language:
* Starlink ANSI C
* Type of Module:
* Library routine
* Invocation:
* void palGeoc( double p, double h, double * r, double *z );
* Arguments:
* p = double (Given)
* latitude (radians)
* h = double (Given)
* height above reference spheroid (geodetic, metres)
* r = double * (Returned)
* distance from Earth axis (AU)
* z = double * (Returned)
* distance from plane of Earth equator (AU)
* Description:
* Convert geodetic position to geocentric.
* Authors:
* PTW: Patrick T. Wallace
* TIMJ: Tim Jenness (JAC, Hawaii)
* {enter_new_authors_here}
* Notes:
* - Geocentric latitude can be obtained by evaluating atan2(z,r)
* - Uses WGS84 reference ellipsoid and calls eraGd2gc
* History:
* 2012-03-01 (TIMJ):
* Initial version moved from palOne2One
* Adapted with permission from the Fortran SLALIB library.
* {enter_further_changes_here}
* Copyright:
* Copyright (C) 2004 Patrick T. Wallace
* Copyright (C) 2012 Science and Technology Facilities Council.
* All Rights Reserved.
* Licence:
* This program is free software: you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation, either
* version 3 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 Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General
* License along with this program. If not, see
* .
* Bugs:
* {note_any_bugs_here}
*-
*/
#include "pal.h"
#include "pal1sofa.h"
void palGeoc ( double p, double h, double *r, double *z ) {
double xyz[3];
const double elong = 0.0; /* Use zero longitude */
const double AU = 1.49597870E11;
/* WGS84 looks to be the closest match */
eraGd2gc( ERFA_WGS84, elong, p, h, xyz );
*r = xyz[0] / (AU * cos(elong) );
*z = xyz[2] / AU;
}