/*============================================================================
  WCSLIB 8.5 - an implementation of the FITS WCS standard.
  Copyright (C) 1995-2025, 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.

  Author: Mark Calabretta, Australia Telescope National Facility, CSIRO.
  http://www.atnf.csiro.au/people/Mark.Calabretta
  $Id: log.c,v 8.5 2025/12/06 13:47:41 mcalabre 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",
  "One or more of the world coordinates were invalid"};


//----------------------------------------------------------------------------

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

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

  const double *xp = x;
  double *logcp = logc;
  int *statp = stat;
  for (int ix = 0; ix < nx; ix++, xp += sx, logcp += slogc, statp++) {
    *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[])

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

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

  return status;
}
