/*============================================================================
*
*   WCSLIB 4.2 - an implementation of the FITS WCS standard.
*   Copyright (C) 1995-2005, Mark Calabretta
*
*   WCSLIB 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.
*
*   WCSLIB 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 WCSLIB; if not, write to the Free Software Foundation, Inc.,
*   59 Temple Place, Suite 330, Boston, MA  02111-1307, USA
*
*   Correspondence concerning WCSLIB may be directed to:
*      Internet email: mcalabre@atnf.csiro.au
*      Postal address: Dr. Mark Calabretta
*                      Australia Telescope National Facility, CSIRO
*                      PO Box 76
*                      Epping NSW 1710
*                      AUSTRALIA
*
*   Author: Mark Calabretta, Australia Telescope National Facility
*   http://www.atnf.csiro.au/~mcalabre/index.html
*   $Id: log.c,v 4.2 2005/09/21 13:21:57 cal103 Exp $
*===========================================================================*/

#include <math.h>

#include "log.h"

/* Map status return value to message. */
const char *log_errmsg[] = {
   "Success",
   "",
   "Invalid log-coordinate reference value",
   "One or more of the x coordinates were invalid"};


/*--------------------------------------------------------------------------*/

int logx2s(
   double crval,
   int nx,
   int sx,
   int slogc,
   const double x[],
   double logc[],
   int stat[])

{
   register int ix;
   register int *statp;
   register const double *xp;
   register double *logcp;


   if (crval <= 0.0) {
      return 2;
   }

   xp = x;
   logcp = logc;
   statp = stat;
   for (ix = 0; ix < nx; ix++, xp += sx, logcp += slogc) {
      *logcp = crval * exp((*xp) / crval);
      *(statp++) = 0;
   }

   return 0;
}

/*--------------------------------------------------------------------------*/

int logs2x(
   double crval,
   int nlogc,
   int slogc,
   int sx,
   const double logc[],
   double x[],
   int stat[])

{
   int status;
   register int ilogc;
   register int *statp;
   register const double *logcp;
   register double *xp;


   if (crval <= 0.0) {
      return 2;
   }

   xp = x;
   logcp = logc;
   statp = stat;
   status = 0;
   for (ilogc = 0; ilogc < nlogc; ilogc++, logcp += slogc, xp += sx) {
      if (*logcp > 0.0) {
         *xp = crval * log(*logcp / crval);
         *(statp++) = 0;
      } else {
         *(statp++) = 1;
         status = 4;
      }
   }

   return status;
}