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DOUBLE PRECISION FUNCTION slDSEP (A1, B1, A2, B2)
*+
* - - - - -
* D S E P
* - - - - -
*
* Angle between two points on a sphere.
*
* (double precision)
*
* Given:
* A1,B1 d spherical coordinates of one point
* A2,B2 d spherical coordinates of the other point
*
* (The spherical coordinates are [RA,Dec], [Long,Lat] etc, in radians.)
*
* The result is the angle, in radians, between the two points. It
* is always positive.
*
* Called: slDS2C, slDSEPV
*
* Last revision: 7 May 2000
*
* Copyright P.T.Wallace. All rights reserved.
*
* 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., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301 USA
*
* Copyright (C) 1995 Association of Universities for Research in Astronomy Inc.
*-
IMPLICIT NONE
DOUBLE PRECISION A1,B1,A2,B2
DOUBLE PRECISION V1(3),V2(3)
DOUBLE PRECISION slDSEPV
* Convert coordinates from spherical to Cartesian.
CALL slDS2C(A1,B1,V1)
CALL slDS2C(A2,B2,V2)
* Angle between the vectors.
slDSEP = slDSEPV(V1,V2)
END
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