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71 lines
2.0 KiB
Fortran
71 lines
2.0 KiB
Fortran
REAL FUNCTION sla_PAV ( V1, V2 )
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*+
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* - - - -
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* P A V
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* - - - -
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*
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* Position angle of one celestial direction with respect to another.
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*
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* (single precision)
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*
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* Given:
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* V1 r(3) direction cosines of one point
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* V2 r(3) direction cosines of the other point
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*
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* (The coordinate frames correspond to RA,Dec, Long,Lat etc.)
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*
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* The result is the bearing (position angle), in radians, of point
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* V2 with respect to point V1. It is in the range +/- pi. The
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* sense is such that if V2 is a small distance east of V1, the
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* bearing is about +pi/2. Zero is returned if the two points
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* are coincident.
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*
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* V1 and V2 do not have to be unit vectors.
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*
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* The routine sla_BEAR performs an equivalent function except
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* that the points are specified in the form of spherical
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* coordinates.
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*
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* Called: sla_DPAV
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*
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* Last revision: 11 September 2005
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*
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* Copyright P.T.Wallace. All rights reserved.
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*
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* License:
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program (see SLA_CONDITIONS); if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place, Suite 330,
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* Boston, MA 02111-1307 USA
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*
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*-
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IMPLICIT NONE
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REAL V1(3), V2(3)
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INTEGER I
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DOUBLE PRECISION D1(3), D2(3)
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DOUBLE PRECISION sla_DPAV
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* Call the double precision version.
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DO I=1,3
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D1(I) = V1(I)
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D2(I) = V2(I)
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END DO
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sla_PAV = REAL(sla_DPAV(D1,D2))
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END
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