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authorJoseph Hunkeler <jhunkeler@gmail.com>2015-07-08 20:46:52 -0400
committerJoseph Hunkeler <jhunkeler@gmail.com>2015-07-08 20:46:52 -0400
commitfa080de7afc95aa1c19a6e6fc0e0708ced2eadc4 (patch)
treebdda434976bc09c864f2e4fa6f16ba1952b1e555 /math/slalib/eqecl.f
downloadiraf-linux-fa080de7afc95aa1c19a6e6fc0e0708ced2eadc4.tar.gz
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+ SUBROUTINE slEQEC (DR, DD, DATE, DL, DB)
+*+
+* - - - - - -
+* E Q E C
+* - - - - - -
+*
+* Transformation from J2000.0 equatorial coordinates to
+* ecliptic coordinates (double precision)
+*
+* Given:
+* DR,DD dp J2000.0 mean RA,Dec (radians)
+* DATE dp TDB (loosely ET) as Modified Julian Date
+* (JD-2400000.5)
+* Returned:
+* DL,DB dp ecliptic longitude and latitude
+* (mean of date, IAU 1980 theory, radians)
+*
+* Called:
+* slDS2C, slPREC, slEPJ, slDMXV, slECMA, slDC2S,
+* slDA2P, slDA1P
+*
+* P.T.Wallace Starlink March 1986
+*
+* Copyright (C) 1995 Rutherford Appleton Laboratory
+*
+* 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 DR,DD,DATE,DL,DB
+
+ DOUBLE PRECISION slEPJ,slDA2P,slDA1P
+
+ DOUBLE PRECISION RMAT(3,3),V1(3),V2(3)
+
+
+
+* Spherical to Cartesian
+ CALL slDS2C(DR,DD,V1)
+
+* Mean J2000 to mean of date
+ CALL slPREC(2000D0,slEPJ(DATE),RMAT)
+ CALL slDMXV(RMAT,V1,V2)
+
+* Equatorial to ecliptic
+ CALL slECMA(DATE,RMAT)
+ CALL slDMXV(RMAT,V2,V1)
+
+* Cartesian to spherical
+ CALL slDC2S(V1,DL,DB)
+
+* Express in conventional ranges
+ DL=slDA2P(DL)
+ DB=slDA1P(DB)
+
+ END