view release on metacpan or  search on metacpan

palsrc/palOapqk.c  view on Meta::CPAN

*     axes, and finally for the tilt of the azimuth or polar axis
*     of the mounting (with appropriate corrections for mount
*     flexures).  Some telescopes would, of course, exhibit other
*     properties which would need to be accounted for at the
*     appropriate point in the sequence.
*
*     - The star-independent apparent-to-observed-place parameters
*     in AOPRMS may be computed by means of the palAoppa routine.
*     If nothing has changed significantly except the time, the
*     palAoppat routine may be used to perform the requisite
*     partial recomputation of AOPRMS.
*
*     - The azimuths etc used by the present routine are with respect
*     to the celestial pole.  Corrections from the terrestrial pole
*     can be computed using palPolmo.


*  History:
*     2012-08-27 (TIMJ):
*        Initial version, direct copy of Fortran SLA
*        Adapted with permission from the Fortran SLALIB library.
*     {enter_further_changes_here}

*  Copyright:
*     Copyright (C) 2004 Patrick T. Wallace
*     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 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 General Public License for more details.
*
*     You should have received a copy of the GNU General Public License
*     along with this program; if not, write to the Free Software
*     Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
*     MA 02110-1301, USA.

*  Bugs:
*     {note_any_bugs_here}
*-
*/

#include <math.h>

#include "pal.h"
#include "palmac.h"

void palOapqk ( const char *type, double ob1, double ob2, const double aoprms[14],
                double *rap, double *dap ) {

  /*  breakpoint for fast/slow refraction algorithm:
   *  zd greater than arctan(4), (see palRefco routine)
   *  or vector z less than cosine(arctan(z)) = 1/sqrt(17) */
  const double zbreak = 0.242535625;

  char c;
  double c1,c2,sphi,cphi,st,ce,xaeo,yaeo,zaeo,v[3],
    xmhdo,ymhdo,zmhdo,az,sz,zdo,tz,dref,zdt,
    xaet,yaet,zaet,xmhda,ymhda,zmhda,diurab,f,hma;

  /*  coordinate type */
  c = type[0];

  /*  coordinates */
  c1 = ob1;
  c2 = ob2;

  /*  sin, cos of latitude */
  sphi = aoprms[1];
  cphi = aoprms[2];

  /*  local apparent sidereal time */
  st = aoprms[13];

  /*  standardise coordinate type */
  if (c == 'r' || c == 'R') {
    c = 'r';
  } else if (c == 'h' || c == 'H') {
    c = 'h';
  } else {
    c = 'a';
  }

  /*  if az,zd convert to cartesian (s=0,e=90) */
  if (c == 'a') {
    ce = sin(c2);
    xaeo = -cos(c1)*ce;
    yaeo = sin(c1)*ce;
    zaeo = cos(c2);
  } else {

    /*     if ra,dec convert to ha,dec */
    if (c == 'r') {
      c1 = st-c1;
    }

    /*     to cartesian -ha,dec */
    palDcs2c( -c1, c2, v );
    xmhdo = v[0];
    ymhdo = v[1];
    zmhdo = v[2];

    /*     to cartesian az,el (s=0,e=90) */
    xaeo = sphi*xmhdo-cphi*zmhdo;
    yaeo = ymhdo;
    zaeo = cphi*xmhdo+sphi*zmhdo;
  }

  /*  azimuth (s=0,e=90) */
  if (xaeo != 0.0 || yaeo != 0.0) {
    az = atan2(yaeo,xaeo);
  } else {
    az = 0.0;
  }