/*============================================================================

    WCSLIB 4.3 - an implementation of the FITS WCS standard.
    Copyright (C) 1995-2007, Mark Calabretta

    This file is part of WCSLIB.

    WCSLIB 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.

    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 Lesser General Public License for
    more details.

    You should have received a copy of the GNU Lesser General Public License
    along with WCSLIB.  If not, see <http://www.gnu.org/licenses/>.

    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 4.3 2007/12/27 05:41:36 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;
}