scottransom/pyslalib

Fetching contributors…
Cannot retrieve contributors at this time
57 lines (49 sloc) 1.61 KB
 SUBROUTINE sla_DCS2C (A, B, V) *+ * - - - - - - * D C 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., 59 Temple Place, Suite 330, * Boston, MA 02111-1307 USA * *- 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