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61 lines
1.7 KiB
Fortran
61 lines
1.7 KiB
Fortran
DOUBLE PRECISION FUNCTION sla_DSEP (A1, B1, A2, B2)
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*+
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* - - - - -
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* D S E P
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* - - - - -
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*
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* Angle between two points on a sphere.
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*
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* (double precision)
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*
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* Given:
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* A1,B1 d spherical coordinates of one point
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* A2,B2 d spherical coordinates of the other point
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*
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* (The spherical coordinates are [RA,Dec], [Long,Lat] etc, in radians.)
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*
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* The result is the angle, in radians, between the two points. It
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* is always positive.
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*
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* Called: sla_DCS2C, sla_DSEPV
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*
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* Last revision: 7 May 2000
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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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DOUBLE PRECISION A1,B1,A2,B2
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DOUBLE PRECISION V1(3),V2(3)
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DOUBLE PRECISION sla_DSEPV
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* Convert coordinates from spherical to Cartesian.
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CALL sla_DCS2C(A1,B1,V1)
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CALL sla_DCS2C(A2,B2,V2)
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* Angle between the vectors.
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sla_DSEP = sla_DSEPV(V1,V2)
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END
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