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/* roots/convergence.c
*
* Copyright (C) 1996, 1997, 1998, 1999, 2000 Reid Priedhorsky, 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 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.
*/
#include <config.h>
#include <gsl/gsl_math.h>
#include <gsl/gsl_errno.h>
#include <gsl/gsl_roots.h>
int
gsl_root_test_interval (double x_lower, double x_upper, double epsabs, double epsrel)
{
const double abs_lower = fabs(x_lower) ;
const double abs_upper = fabs(x_upper) ;
double min_abs, tolerance;
if (epsrel < 0.0)
GSL_ERROR ("relative tolerance is negative", GSL_EBADTOL);
if (epsabs < 0.0)
GSL_ERROR ("absolute tolerance is negative", GSL_EBADTOL);
if (x_lower > x_upper)
GSL_ERROR ("lower bound larger than upper bound", GSL_EINVAL);
if ((x_lower > 0.0 && x_upper > 0.0) || (x_lower < 0.0 && x_upper < 0.0))
{
min_abs = GSL_MIN_DBL(abs_lower, abs_upper) ;
}
else
{
min_abs = 0;
}
tolerance = epsabs + epsrel * min_abs ;
if (fabs(x_upper - x_lower) < tolerance)
return GSL_SUCCESS;
return GSL_CONTINUE ;
}
int
gsl_root_test_delta (double x1, double x0, double epsabs, double epsrel)
{
const double tolerance = epsabs + epsrel * fabs(x1) ;
if (epsrel < 0.0)
GSL_ERROR ("relative tolerance is negative", GSL_EBADTOL);
if (epsabs < 0.0)
GSL_ERROR ("absolute tolerance is negative", GSL_EBADTOL);
if (fabs(x1 - x0) < tolerance || x1 == x0)
return GSL_SUCCESS;
return GSL_CONTINUE ;
}
int
gsl_root_test_residual (double f, double epsabs)
{
if (epsabs < 0.0)
GSL_ERROR ("absolute tolerance is negative", GSL_EBADTOL);
if (fabs(f) < epsabs)
return GSL_SUCCESS;
return GSL_CONTINUE ;
}
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