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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
*-
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
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