mirror of
https://github.com/eddyem/BTA_lib.git
synced 2025-12-06 02:35:20 +03:00
71 lines
1.9 KiB
Fortran
71 lines
1.9 KiB
Fortran
REAL FUNCTION sla_SEPV (V1, V2)
|
|
*+
|
|
* - - - - -
|
|
* S E P V
|
|
* - - - - -
|
|
*
|
|
* Angle between two vectors.
|
|
*
|
|
* (single precision)
|
|
*
|
|
* Given:
|
|
* V1 r(3) first vector
|
|
* V2 r(3) second vector
|
|
*
|
|
* The result is the angle, in radians, between the two vectors. It
|
|
* is always positive.
|
|
*
|
|
* Notes:
|
|
*
|
|
* 1 There is no requirement for the vectors to be unit length.
|
|
*
|
|
* 2 If either vector is null, zero is returned.
|
|
*
|
|
* 3 The simplest formulation would use dot product alone. However,
|
|
* this would reduce the accuracy for angles near zero and pi. The
|
|
* algorithm uses both cross product and dot product, which maintains
|
|
* accuracy for all sizes of angle.
|
|
*
|
|
* Called: sla_DSEPV
|
|
*
|
|
* 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., 59 Temple Place, Suite 330,
|
|
* Boston, MA 02111-1307 USA
|
|
*
|
|
*-
|
|
|
|
IMPLICIT NONE
|
|
|
|
REAL V1(3),V2(3)
|
|
|
|
INTEGER I
|
|
DOUBLE PRECISION DV1(3),DV2(3)
|
|
DOUBLE PRECISION sla_DSEPV
|
|
|
|
|
|
|
|
* Use double precision version.
|
|
DO I=1,3
|
|
DV1(I) = DBLE(V1(I))
|
|
DV2(I) = DBLE(V2(I))
|
|
END DO
|
|
sla_SEPV = REAL(sla_DSEPV(DV1,DV2))
|
|
|
|
END
|