1 files changed, 83 insertions, 0 deletions
diff --git a/ast/pal/palGeoc.c b/ast/pal/palGeoc.c
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+++ b/ast/pal/palGeoc.c
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+/*
+*+
+*  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
+*     <http://www.gnu.org/licenses/>.
+
+*  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;
+}