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/* interpolation/interp_poly.c
*
* Copyright (C) 2001 DAN, HO-JIN
*
* 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 <math.h>
#include <gsl/gsl_errno.h>
#include <gsl/gsl_poly.h>
#include <gsl/gsl_interp.h>
typedef struct
{
double *d;
double *coeff;
double *work;
}
polynomial_state_t;
static void *
polynomial_alloc (size_t size)
{
polynomial_state_t *state =
(polynomial_state_t *) malloc (sizeof (polynomial_state_t));
if (state == 0)
{
GSL_ERROR_NULL ("failed to allocate space for polynomial state",
GSL_ENOMEM);
}
state->d = (double *) malloc (sizeof (double) * size);
if (state->d == 0)
{
free (state);
GSL_ERROR_NULL ("failed to allocate space for d", GSL_ENOMEM);
}
state->coeff = (double *) malloc (sizeof (double) * size);
if (state->coeff == 0)
{
free (state->d);
free (state);
GSL_ERROR_NULL ("failed to allocate space for d", GSL_ENOMEM);
}
state->work = (double *) malloc (sizeof (double) * size);
if (state->work == 0)
{
free (state->coeff);
free (state->d);
free (state);
GSL_ERROR_NULL ("failed to allocate space for d", GSL_ENOMEM);
}
return state;
}
static int
polynomial_init (void *vstate,
const double xa[], const double ya[], size_t size)
{
polynomial_state_t *state = (polynomial_state_t *) vstate;
int status = gsl_poly_dd_init (state->d, xa, ya, size);
return status;
}
static int
polynomial_eval (const void *vstate,
const double xa[], const double ya[], size_t size, double x,
gsl_interp_accel * acc, double *y)
{
const polynomial_state_t *state = (const polynomial_state_t *) vstate;
*y = gsl_poly_dd_eval (state->d, xa, size, x);
return GSL_SUCCESS;
}
static int
polynomial_deriv (const void *vstate,
const double xa[], const double ya[], size_t size, double x,
gsl_interp_accel * acc, double *y)
{
const polynomial_state_t *state = (const polynomial_state_t *) vstate;
gsl_poly_dd_taylor (state->coeff, x, state->d, xa, size, state->work);
*y = state->coeff[1];
return GSL_SUCCESS;
}
static int
polynomial_deriv2 (const void *vstate,
const double xa[], const double ya[], size_t size,
double x, gsl_interp_accel * acc, double *y)
{
const polynomial_state_t *state = (const polynomial_state_t *) vstate;
gsl_poly_dd_taylor (state->coeff, x, state->d, xa, size, state->work);
*y = 2.0 * state->coeff[2];
return GSL_SUCCESS;
}
static int
polynomial_integ (const void *vstate, const double xa[], const double ya[],
size_t size, gsl_interp_accel * acc, double a, double b,
double *result)
{
const polynomial_state_t *state = (const polynomial_state_t *) vstate;
size_t i;
double sum;
gsl_poly_dd_taylor (state->coeff, 0.0, state->d, xa, size, state->work);
sum = state->coeff[0] * (b - a);
for (i = 1; i < size; i++)
{
sum += state->coeff[i] * (pow (b, i + 1) - pow (a, i + 1)) / (i + 1.0);
}
*result = sum;
return GSL_SUCCESS;
}
static void
polynomial_free (void *vstate)
{
polynomial_state_t *state = (polynomial_state_t *) vstate;
free (state->d);
free (state->coeff);
free (state->work);
free (state);
}
static const gsl_interp_type polynomial_type = {
"polynomial",
3,
&polynomial_alloc,
&polynomial_init,
&polynomial_eval,
&polynomial_deriv,
&polynomial_deriv2,
&polynomial_integ,
&polynomial_free,
};
const gsl_interp_type *gsl_interp_polynomial = &polynomial_type;
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