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SUBROUTINE sla_DTP2S (XI, ETA, RAZ, DECZ, RA, DEC)
*+
* - - - - - -
* D T P 2 S
* - - - - - -
*
* Transform tangent plane coordinates into spherical
* (double precision)
*
* Given:
* XI,ETA dp tangent plane rectangular coordinates
* RAZ,DECZ dp spherical coordinates of tangent point
*
* Returned:
* RA,DEC dp spherical coordinates (0-2pi,+/-pi/2)
*
* Called: sla_DRANRM
*
* P.T.Wallace Starlink 24 July 1995
*
* Copyright (C) 1995 Rutherford Appleton Laboratory
*
* License:
* 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 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 (see SLA_CONDITIONS); if not, write to the
* Free Software Foundation, Inc., 59 Temple Place, Suite 330,
* Boston, MA 02111-1307 USA
*
*-
IMPLICIT NONE
DOUBLE PRECISION XI,ETA,RAZ,DECZ,RA,DEC
DOUBLE PRECISION sla_DRANRM
DOUBLE PRECISION SDECZ,CDECZ,DENOM
SDECZ=SIN(DECZ)
CDECZ=COS(DECZ)
DENOM=CDECZ-ETA*SDECZ
RA=sla_DRANRM(ATAN2(XI,DENOM)+RAZ)
DEC=ATAN2(SDECZ+ETA*CDECZ,SQRT(XI*XI+DENOM*DENOM))
END