update ast 8.6.2

1 files changed, 142 insertions, 0 deletions

diff --git a/ast/pal/palDe2h.c b/ast/pal/palDe2h.c
new file mode 100644
index 0000000..a250e9e
--- /dev/null
+++ b/ast/pal/palDe2h.c
@@ -0,0 +1,142 @@
+/*
+*+
+*  Name:
+*     palDe2h
+
+*  Purpose:
+*     Equatorial to horizon coordinates: HA,Dec to Az,E
+
+*  Language:
+*     Starlink ANSI C
+
+*  Type of Module:
+*     Library routine
+
+*  Invocation:
+*     palDe2h( double ha, double dec, double phi, double * az, double * el );
+
+*  Arguments:
+*     ha = double * (Given)
+*        Hour angle (radians)
+*     dec = double * (Given)
+*        Declination (radians)
+*     phi = double (Given)
+*        Observatory latitude (radians)
+*     az = double * (Returned)
+*        Azimuth (radians)
+*     el = double * (Returned)
+*        Elevation (radians)
+
+*  Description:
+*     Convert equatorial to horizon coordinates.
+
+*  Authors:
+*     PTW: Pat Wallace (STFC)
+*     TIMJ: Tim Jenness (JAC, Hawaii)
+*     {enter_new_authors_here}
+
+*  Notes:
+*     - All the arguments are angles in radians.
+*     - Azimuth is returned in the range 0-2pi;  north is zero,
+*       and east is +pi/2.  Elevation is returned in the range
+*       +/-pi/2.
+*     - The latitude must be geodetic.  In critical applications,
+*       corrections for polar motion should be applied.
+*     - In some applications it will be important to specify the
+*       correct type of hour angle and declination in order to
+*       produce the required type of azimuth and elevation.  In
+*       particular, it may be important to distinguish between
+*       elevation as affected by refraction, which would
+*       require the "observed" HA,Dec, and the elevation
+*       in vacuo, which would require the "topocentric" HA,Dec.
+*       If the effects of diurnal aberration can be neglected, the
+*       "apparent" HA,Dec may be used instead of the topocentric
+*       HA,Dec.
+*     - No range checking of arguments is carried out.
+*     - In applications which involve many such calculations, rather
+*       than calling the present routine it will be more efficient to
+*       use inline code, having previously computed fixed terms such
+*       as sine and cosine of latitude, and (for tracking a star)
+*       sine and cosine of declination.
+
+*  History:
+*     2012-02-08 (TIMJ):
+*        Initial version with documentation taken from Fortran SLA
+*        Adapted with permission from the Fortran SLALIB library.
+*     {enter_further_changes_here}
+
+*  Copyright:
+*     Copyright (C) 1995 Rutherford Appleton Laboratory
+*     Copyright (C) 2012 Science and Technology Facilities Council.
+*     All Rights Reserved.
+
+*  Licence:
+*     This program is free software: you can redistribute it and/or
+*     modify it under the terms of the GNU Lesser General Public
+*     License as published by the Free Software Foundation, either
+*     version 3 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 Lesser General Public License for more details.
+*
+*     You should have received a copy of the GNU Lesser General
+*     License along with this program.  If not, see
+*     <http://www.gnu.org/licenses/>.
+
+*  Bugs:
+*     {note_any_bugs_here}
+*-
+*/
+
+#include "pal.h"
+#include "palmac.h"
+#include <math.h>
+
+void
+palDe2h ( double ha, double dec, double phi, double *az, double *el) {
+
+  double sh;
+  double ch;
+  double sd;
+  double cd;
+  double sp;
+  double cp;
+
+  double a;
+
+  double x;
+  double y;
+  double z;
+  double r;
+
+  /*  Useful trig functions */
+  sh = sin(ha);
+  ch = cos(ha);
+  sd = sin(dec);
+  cd = cos(dec);
+  sp = sin(phi);
+  cp = cos(phi);
+
+  /*  Az,El as x,y,z */
+  x = -ch * cd * sp + sd * cp;
+  y = -sh * cd;
+  z = ch * cd * cp + sd * sp;
+
+  /*  To spherical */
+  r = sqrt(x * x + y * y);
+  if (r == 0.) {
+    a = 0.;
+  } else {
+    a = atan2(y, x);
+  }
+  if (a < 0.) {
+    a += PAL__D2PI;
+  }
+  *az = a;
+  *el = atan2(z, r);
+
+  return;
+}