|
Packit |
67cb25 |
/* integration/chebyshev2.c
|
|
Packit |
67cb25 |
*
|
|
Packit |
67cb25 |
* Copyright (C) 2017 Konrad Griessinger, Patrick Alken
|
|
Packit |
67cb25 |
*
|
|
Packit |
67cb25 |
* This program is free software; you can redistribute it and/or modify
|
|
Packit |
67cb25 |
* it under the terms of the GNU General Public License as published by
|
|
Packit |
67cb25 |
* the Free Software Foundation; either version 3 of the License, or (at
|
|
Packit |
67cb25 |
* your option) any later version.
|
|
Packit |
67cb25 |
*
|
|
Packit |
67cb25 |
* This program is distributed in the hope that it will be useful, but
|
|
Packit |
67cb25 |
* WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
Packit |
67cb25 |
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
Packit |
67cb25 |
* General Public License for more details.
|
|
Packit |
67cb25 |
*
|
|
Packit |
67cb25 |
* You should have received a copy of the GNU General Public License
|
|
Packit |
67cb25 |
* along with this program; if not, write to the Free Software
|
|
Packit |
67cb25 |
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
|
|
Packit |
67cb25 |
*/
|
|
Packit |
67cb25 |
|
|
Packit |
67cb25 |
/*
|
|
Packit |
67cb25 |
* The code in this module is based on IQPACK, specifically the LGPL
|
|
Packit |
67cb25 |
* implementation found in HERMITE_RULE:
|
|
Packit |
67cb25 |
* https://people.sc.fsu.edu/~jburkardt/c_src/hermite_rule/hermite_rule.html
|
|
Packit |
67cb25 |
*/
|
|
Packit |
67cb25 |
|
|
Packit |
67cb25 |
#include <stdio.h>
|
|
Packit |
67cb25 |
#include <gsl/gsl_errno.h>
|
|
Packit |
67cb25 |
#include <gsl/gsl_math.h>
|
|
Packit |
67cb25 |
#include <gsl/gsl_integration.h>
|
|
Packit |
67cb25 |
#include <gsl/gsl_sf_gamma.h>
|
|
Packit |
67cb25 |
|
|
Packit |
67cb25 |
static int
|
|
Packit |
67cb25 |
chebyshev2_check(const size_t n, const gsl_integration_fixed_params * params)
|
|
Packit |
67cb25 |
{
|
|
Packit |
67cb25 |
(void) n;
|
|
Packit |
67cb25 |
|
|
Packit |
67cb25 |
if (fabs(params->b - params->a) <= GSL_DBL_EPSILON)
|
|
Packit |
67cb25 |
{
|
|
Packit |
67cb25 |
GSL_ERROR("|b - a| too small", GSL_EDOM);
|
|
Packit |
67cb25 |
}
|
|
Packit |
67cb25 |
else if (params->a >= params->b)
|
|
Packit |
67cb25 |
{
|
|
Packit |
67cb25 |
GSL_ERROR("lower integration limit must be smaller than upper limit", GSL_EDOM);
|
|
Packit |
67cb25 |
}
|
|
Packit |
67cb25 |
else
|
|
Packit |
67cb25 |
{
|
|
Packit |
67cb25 |
return GSL_SUCCESS;
|
|
Packit |
67cb25 |
}
|
|
Packit |
67cb25 |
}
|
|
Packit |
67cb25 |
|
|
Packit |
67cb25 |
static int
|
|
Packit |
67cb25 |
chebyshev2_init(const size_t n, double * diag, double * subdiag, gsl_integration_fixed_params * params)
|
|
Packit |
67cb25 |
{
|
|
Packit |
67cb25 |
size_t i;
|
|
Packit |
67cb25 |
|
|
Packit |
67cb25 |
/* construct the diagonal and subdiagonal elements of Jacobi matrix */
|
|
Packit |
67cb25 |
for (i = 0; i < n; i++)
|
|
Packit |
67cb25 |
{
|
|
Packit |
67cb25 |
diag[i] = 0.0;
|
|
Packit |
67cb25 |
subdiag[i] = 0.5;
|
|
Packit |
67cb25 |
}
|
|
Packit |
67cb25 |
|
|
Packit |
67cb25 |
params->zemu = M_PI_2;
|
|
Packit |
67cb25 |
params->shft = 0.5*(params->b + params->a);
|
|
Packit |
67cb25 |
params->slp = 0.5*(params->b - params->a);
|
|
Packit |
67cb25 |
params->al = 0.5;
|
|
Packit |
67cb25 |
params->be = 0.5;
|
|
Packit |
67cb25 |
|
|
Packit |
67cb25 |
return GSL_SUCCESS;
|
|
Packit |
67cb25 |
}
|
|
Packit |
67cb25 |
|
|
Packit |
67cb25 |
static const gsl_integration_fixed_type chebyshev2_type =
|
|
Packit |
67cb25 |
{
|
|
Packit |
67cb25 |
chebyshev2_check,
|
|
Packit |
67cb25 |
chebyshev2_init
|
|
Packit |
67cb25 |
};
|
|
Packit |
67cb25 |
|
|
Packit |
67cb25 |
const gsl_integration_fixed_type *gsl_integration_fixed_chebyshev2 = &chebyshev2_type;
|