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/* ode-initval/evolve.c
*
* Copyright (C) 1996, 1997, 1998, 1999, 2000 Gerard Jungman
*
* 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 2 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.
*/
/* Author: G. Jungman
*/
#include <config.h>
#include <string.h>
#include <stdlib.h>
#include <gsl/gsl_math.h>
#include <gsl/gsl_errno.h>
#include <gsl/gsl_odeiv.h>
#include "odeiv_util.h"
gsl_odeiv_evolve *
gsl_odeiv_evolve_alloc (size_t dim)
{
gsl_odeiv_evolve *e =
(gsl_odeiv_evolve *) malloc (sizeof (gsl_odeiv_evolve));
if (e == 0)
{
GSL_ERROR_NULL ("failed to allocate space for evolve struct",
GSL_ENOMEM);
}
e->y0 = (double *) malloc (dim * sizeof (double));
if (e->y0 == 0)
{
free (e);
GSL_ERROR_NULL ("failed to allocate space for y0", GSL_ENOMEM);
}
e->yerr = (double *) malloc (dim * sizeof (double));
if (e->yerr == 0)
{
free (e->y0);
free (e);
GSL_ERROR_NULL ("failed to allocate space for yerr", GSL_ENOMEM);
}
e->dydt_in = (double *) malloc (dim * sizeof (double));
if (e->dydt_in == 0)
{
free (e->yerr);
free (e->y0);
free (e);
GSL_ERROR_NULL ("failed to allocate space for dydt_in", GSL_ENOMEM);
}
e->dydt_out = (double *) malloc (dim * sizeof (double));
if (e->dydt_out == 0)
{
free (e->dydt_in);
free (e->yerr);
free (e->y0);
free (e);
GSL_ERROR_NULL ("failed to allocate space for dydt_out", GSL_ENOMEM);
}
e->dimension = dim;
e->count = 0;
e->failed_steps = 0;
e->last_step = 0.0;
return e;
}
int
gsl_odeiv_evolve_reset (gsl_odeiv_evolve * e)
{
e->count = 0;
e->failed_steps = 0;
e->last_step = 0.0;
return GSL_SUCCESS;
}
void
gsl_odeiv_evolve_free (gsl_odeiv_evolve * e)
{
free (e->dydt_out);
free (e->dydt_in);
free (e->yerr);
free (e->y0);
free (e);
}
/* Evolution framework method.
*
* Uses an adaptive step control object
*/
int
gsl_odeiv_evolve_apply (gsl_odeiv_evolve * e,
gsl_odeiv_control * con,
gsl_odeiv_step * step,
const gsl_odeiv_system * dydt,
double *t, double t1, double *h, double y[])
{
const double t0 = *t;
double h0 = *h;
int step_status;
int final_step = 0;
double dt = t1 - t0; /* remaining time, possibly less than h */
if (e->dimension != step->dimension)
{
GSL_ERROR ("step dimension must match evolution size", GSL_EINVAL);
}
if ((dt < 0.0 && h0 > 0.0) || (dt > 0.0 && h0 < 0.0))
{
GSL_ERROR ("step direction must match interval direction", GSL_EINVAL);
}
/* No need to copy if we cannot control the step size. */
if (con != NULL)
{
DBL_MEMCPY (e->y0, y, e->dimension);
}
/* Calculate initial dydt once if the method can benefit. */
if (step->type->can_use_dydt_in)
{
int status = GSL_ODEIV_FN_EVAL (dydt, t0, y, e->dydt_in);
if (status)
{
return status;
}
}
try_step:
if ((dt >= 0.0 && h0 > dt) || (dt < 0.0 && h0 < dt))
{
h0 = dt;
final_step = 1;
}
else
{
final_step = 0;
}
if (step->type->can_use_dydt_in)
{
step_status =
gsl_odeiv_step_apply (step, t0, h0, y, e->yerr, e->dydt_in,
e->dydt_out, dydt);
}
else
{
step_status =
gsl_odeiv_step_apply (step, t0, h0, y, e->yerr, NULL, e->dydt_out,
dydt);
}
/* Check for stepper internal failure */
if (step_status != GSL_SUCCESS)
{
*h = h0; /* notify user of step-size which caused the failure */
return step_status;
}
e->count++;
e->last_step = h0;
if (final_step)
{
*t = t1;
}
else
{
*t = t0 + h0;
}
if (con != NULL)
{
/* Check error and attempt to adjust the step. */
const int hadjust_status
= gsl_odeiv_control_hadjust (con, step, y, e->yerr, e->dydt_out, &h0);
if (hadjust_status == GSL_ODEIV_HADJ_DEC)
{
/* Step was decreased. Undo and go back to try again. */
DBL_MEMCPY (y, e->y0, dydt->dimension);
e->failed_steps++;
goto try_step;
}
}
*h = h0; /* suggest step size for next time-step */
return step_status;
}
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