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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