/*
*+
* Name:
* palDtp2s
* Purpose:
* Tangent plane to spherical coordinates
* Language:
* Starlink ANSI C
* Type of Module:
* Library routine
* Invocation:
* palDtp2s( double xi, double eta, double raz, double decz,
* double *ra, double *dec);
* Arguments:
* xi = double (Given)
* First rectangular coordinate on tangent plane (radians)
* eta = double (Given)
* Second rectangular coordinate on tangent plane (radians)
* raz = double (Given)
* RA spherical coordinate of tangent point (radians)
* decz = double (Given)
* Dec spherical coordinate of tangent point (radians)
* ra = double * (Returned)
* RA spherical coordinate of point to be projected (radians)
* dec = double * (Returned)
* Dec spherical coordinate of point to be projected (radians)
* Description:
* Transform tangent plane coordinates into spherical.
* Authors:
* PTW: Pat Wallace (STFC)
* TIMJ: Tim Jenness (JAC, Hawaii)
* {enter_new_authors_here}
* History:
* 2012-02-08 (TIMJ):
* Initial version with documentation taken from Fortran SLA
* {enter_further_changes_here}
* Copyright:
* 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 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 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, Fifth Floor, Boston, MA 02110-1301
* USA.
* Bugs:
* {note_any_bugs_here}
*-
*/
#include "pal.h"
#include "sofa.h"
#include
void
palDtp2s ( double xi, double eta, double raz, double decz,
double *ra, double *dec ) {
double cdecz;
double denom;
double sdecz;
double d;
sdecz = sin(decz);
cdecz = cos(decz);
denom = cdecz - eta * sdecz;
d = atan2(xi, denom) + raz;
*ra = iauAnp(d);
*dec = atan2(sdecz + eta * cdecz, sqrt(xi * xi + denom * denom));
return;
}