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Diffstat (limited to 'math/slalib/dcs2c.f')
| -rw-r--r-- | math/slalib/dcs2c.f | 57 |
1 files changed, 57 insertions, 0 deletions
diff --git a/math/slalib/dcs2c.f b/math/slalib/dcs2c.f new file mode 100644 index 00000000..59a70b98 --- /dev/null +++ b/math/slalib/dcs2c.f @@ -0,0 +1,57 @@ + SUBROUTINE slDS2C (A, B, V) +*+ +* - - - - - - +* D S 2 C +* - - - - - - +* +* Spherical coordinates to direction cosines (double precision) +* +* Given: +* A,B d spherical coordinates in radians +* (RA,Dec), (long,lat) etc. +* +* Returned: +* V d(3) x,y,z unit vector +* +* The spherical coordinates are longitude (+ve anticlockwise looking +* from the +ve latitude pole) and latitude. The Cartesian coordinates +* are right handed, with the x axis at zero longitude and latitude, and +* the z axis at the +ve latitude pole. +* +* Last revision: 26 December 2004 +* +* 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 A,B,V(3) + + DOUBLE PRECISION COSB + + + COSB = COS(B) + + V(1) = COS(A)*COSB + V(2) = SIN(A)*COSB + V(3) = SIN(B) + + END |