/* multifit/fsolver.c

 * 

 * Copyright (C) 1996, 1997, 1998, 1999, 2000, 2007 Brian Gough

 * 

 * 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.

 */

#include <config.h>

#include <stdlib.h>

#include <string.h>

#include <gsl/gsl_errno.h>

#include <gsl/gsl_multifit_nlin.h>

gsl_multifit_fsolver *

gsl_multifit_fsolver_alloc (const gsl_multifit_fsolver_type * T, 

                            size_t n, size_t p) 

{

  int status;

  gsl_multifit_fsolver * s;

  if (n < p)

    {

      GSL_ERROR_VAL ("insufficient data points, n < p", GSL_EINVAL, 0);

    }

  s = (gsl_multifit_fsolver *) malloc (sizeof (gsl_multifit_fsolver));

  if (s == 0)

    {

      GSL_ERROR_VAL ("failed to allocate space for multifit solver struct",

                        GSL_ENOMEM, 0);

    }

  s->x = gsl_vector_calloc (p);

  if (s->x == 0) 

    {

      free (s);

      GSL_ERROR_VAL ("failed to allocate space for x", GSL_ENOMEM, 0);

    }

  s->f = gsl_vector_calloc (n);

  if (s->f == 0) 

    {

      gsl_vector_free (s->x);

      free (s);

      GSL_ERROR_VAL ("failed to allocate space for f", GSL_ENOMEM, 0);

    }

  s->dx = gsl_vector_calloc (p);

  if (s->dx == 0) 

    {

      gsl_vector_free (s->x);

      gsl_vector_free (s->f);

      free (s);

      GSL_ERROR_VAL ("failed to allocate space for dx", GSL_ENOMEM, 0);

    }

  s->state = malloc (T->size);

  if (s->state == 0)

    {

      gsl_vector_free (s->dx);

      gsl_vector_free (s->x);

      gsl_vector_free (s->f);

      free (s);         /* exception in constructor, avoid memory leak */

      GSL_ERROR_VAL ("failed to allocate space for multifit solver state",

                        GSL_ENOMEM, 0);

    }

  s->type = T ;

  status = (s->type->alloc)(s->state, n, p);

  if (status != GSL_SUCCESS)

    {

      (s->type->free)(s->state);

      free (s->state);

      gsl_vector_free (s->dx);

      gsl_vector_free (s->x);

      gsl_vector_free (s->f);

      free (s);         /* exception in constructor, avoid memory leak */

      GSL_ERROR_VAL ("failed to set solver", status, 0);

    }

  s->function = NULL;

  return s;

}

int

gsl_multifit_fsolver_set (gsl_multifit_fsolver * s, 

                          gsl_multifit_function * f, 

                          const gsl_vector * x)

{

  if (s->f->size != f->n)

    {

      GSL_ERROR ("function size does not match solver", GSL_EBADLEN);

    }

  if (s->x->size != x->size)

    {

      GSL_ERROR ("vector length does not match solver", GSL_EBADLEN);

    }  

  s->function = f;

  gsl_vector_memcpy(s->x,x);

  return (s->type->set) (s->state, s->function, s->x, s->f, s->dx);

}

int

gsl_multifit_fsolver_iterate (gsl_multifit_fsolver * s)

{

  return (s->type->iterate) (s->state, s->function, s->x, s->f, s->dx);

}

int

gsl_multifit_fsolver_driver (gsl_multifit_fsolver * s,

                             const size_t maxiter,

                             const double epsabs,

                             const double epsrel)

{

  int status;

  size_t iter = 0;

  do  

    {   

      status = gsl_multifit_fsolver_iterate (s);

      if (status) 

        break;

      /* test for convergence */

      status = gsl_multifit_test_delta (s->dx, s->x, epsabs, epsrel);

    }   

  while (status == GSL_CONTINUE && ++iter < maxiter);

  return status;

} /* gsl_multifit_fdfsolver_driver() */

void

gsl_multifit_fsolver_free (gsl_multifit_fsolver * s)

{

  RETURN_IF_NULL (s);

  (s->type->free) (s->state);

  free (s->state);

  gsl_vector_free (s->dx);

  gsl_vector_free (s->x);

  gsl_vector_free (s->f);

  free (s);

}

const char *

gsl_multifit_fsolver_name (const gsl_multifit_fsolver * s)

{

  return s->type->name;

}

gsl_vector *

gsl_multifit_fsolver_position (const gsl_multifit_fsolver * s)

{

  return s->x;

}