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+.help dtp2v Jun99 "Slalib Package"
+.nf
+
+ SUBROUTINE slDTPV (XI, ETA, V0, V)
+
+ - - - - - -
+ D T P V
+ - - - - - -
+
+ Given the tangent-plane coordinates of a star and the direction
+ cosines of the tangent point, determine the direction cosines
+ of the star.
+
+ (double precision)
+
+ Given:
+ XI,ETA d tangent plane coordinates of star
+ V0 d(3) direction cosines of tangent point
+
+ Returned:
+ V d(3) direction cosines of star
+
+ Notes:
+
+ 1 If vector V0 is not of unit length, the returned vector V will
+ be wrong.
+
+ 2 If vector V0 points at a pole, the returned vector V will be
+ based on the arbitrary assumption that the RA of the tangent
+ point is zero.
+
+ 3 This routine is the Cartesian equivalent of the routine slDTPS.
+
+ P.T.Wallace Starlink 11 February 1995
+
+ Copyright (C) 1995 Rutherford Appleton Laboratory
+ Copyright (C) 1995 Association of Universities for Research in Astronomy Inc.
+
+.fi
+.endhelp