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/* specfunc/bessel_y.c
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*
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* Copyright (C) 1996, 1997, 1998, 1999, 2000 Gerard Jungman
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 3 of the License, or (at
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* your option) any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*/
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/* Author: G. Jungman */
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#include <config.h>
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#include <gsl/gsl_math.h>
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#include <gsl/gsl_errno.h>
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#include <gsl/gsl_sf_pow_int.h>
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#include <gsl/gsl_sf_gamma.h>
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#include <gsl/gsl_sf_trig.h>
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#include <gsl/gsl_sf_bessel.h>
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#include "error.h"
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#include "bessel.h"
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#include "bessel_olver.h"
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/*-*-*-*-*-*-*-*-*-*-*-* Private Section *-*-*-*-*-*-*-*-*-*-*-*/
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/* [Abramowitz+Stegun, 10.1.3]
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* with lmax=15, precision ~ 15D for x < 3
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*
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* checked OK [GJ] Wed May 13 15:41:25 MDT 1998
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*/
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static int bessel_yl_small_x(int l, const double x, gsl_sf_result * result)
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{
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gsl_sf_result num_fact;
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double den = gsl_sf_pow_int(x, l+1);
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int stat_df = gsl_sf_doublefact_e(2*l-1, &num_fact);
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if(stat_df != GSL_SUCCESS || den == 0.0) {
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OVERFLOW_ERROR(result);
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}
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else {
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const int lmax = 200;
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double t = -0.5*x*x;
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double sum = 1.0;
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double t_coeff = 1.0;
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double t_power = 1.0;
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double delta;
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int i;
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for(i=1; i<=lmax; i++) {
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t_coeff /= i*(2*(i-l) - 1);
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t_power *= t;
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delta = t_power*t_coeff;
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sum += delta;
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if(fabs(delta/sum) < 0.5*GSL_DBL_EPSILON) break;
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}
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result->val = -num_fact.val/den * sum;
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result->err = GSL_DBL_EPSILON * fabs(result->val);
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return GSL_SUCCESS;
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}
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}
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/*-*-*-*-*-*-*-*-*-*-*-* Functions with Error Codes *-*-*-*-*-*-*-*-*-*-*-*/
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int gsl_sf_bessel_y0_e(const double x, gsl_sf_result * result)
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{
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/* CHECK_POINTER(result) */
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if(x <= 0.0) {
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DOMAIN_ERROR(result);
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}
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else if(1.0/GSL_DBL_MAX > 0.0 && x < 1.0/GSL_DBL_MAX) {
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OVERFLOW_ERROR(result);
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}
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else {
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gsl_sf_result cos_result;
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const int stat = gsl_sf_cos_e(x, &cos_result);
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result->val = -cos_result.val/x;
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result->err = fabs(cos_result.err/x);
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result->err += 2.0 * GSL_DBL_EPSILON * fabs(result->val);
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return stat;
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}
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}
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int gsl_sf_bessel_y1_e(const double x, gsl_sf_result * result)
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{
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/* CHECK_POINTER(result) */
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if(x <= 0.0) {
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DOMAIN_ERROR(result);
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}
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else if(x < 1.0/GSL_SQRT_DBL_MAX) {
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OVERFLOW_ERROR(result);
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}
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else if(x < 0.25) {
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const double y = x*x;
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const double c1 = 1.0/2.0;
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const double c2 = -1.0/8.0;
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const double c3 = 1.0/144.0;
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const double c4 = -1.0/5760.0;
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const double c5 = 1.0/403200.0;
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const double c6 = -1.0/43545600.0;
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const double sum = 1.0 + y*(c1 + y*(c2 + y*(c3 + y*(c4 + y*(c5 + y*c6)))));
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result->val = -sum/y;
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result->err = GSL_DBL_EPSILON * fabs(result->val);
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return GSL_SUCCESS;
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}
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else {
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gsl_sf_result cos_result;
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gsl_sf_result sin_result;
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const int stat_cos = gsl_sf_cos_e(x, &cos_result);
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const int stat_sin = gsl_sf_sin_e(x, &sin_result);
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const double cx = cos_result.val;
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const double sx = sin_result.val;
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result->val = -(cx/x + sx)/x;
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result->err = (fabs(cos_result.err/x) + sin_result.err)/fabs(x);
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result->err += GSL_DBL_EPSILON * (fabs(sx/x) + fabs(cx/(x*x)));
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return GSL_ERROR_SELECT_2(stat_cos, stat_sin);
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}
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}
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int gsl_sf_bessel_y2_e(const double x, gsl_sf_result * result)
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{
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/* CHECK_POINTER(result) */
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if(x <= 0.0) {
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DOMAIN_ERROR(result);
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}
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else if(x < 1.0/GSL_ROOT3_DBL_MAX) {
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OVERFLOW_ERROR(result);
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}
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else if(x < 0.5) {
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const double y = x*x;
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const double c1 = 1.0/6.0;
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const double c2 = 1.0/24.0;
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const double c3 = -1.0/144.0;
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const double c4 = 1.0/3456.0;
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const double c5 = -1.0/172800.0;
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const double c6 = 1.0/14515200.0;
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const double c7 = -1.0/1828915200.0;
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const double sum = 1.0 + y*(c1 + y*(c2 + y*(c3 + y*(c4 + y*(c5 + y*(c6 + y*c7))))));
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result->val = -3.0/(x*x*x) * sum;
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result->err = GSL_DBL_EPSILON * fabs(result->val);
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return GSL_SUCCESS;
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}
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else {
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gsl_sf_result cos_result;
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gsl_sf_result sin_result;
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const int stat_cos = gsl_sf_cos_e(x, &cos_result);
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const int stat_sin = gsl_sf_sin_e(x, &sin_result);
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const double sx = sin_result.val;
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const double cx = cos_result.val;
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const double a = 3.0/(x*x);
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result->val = (1.0 - a)/x * cx - a * sx;
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result->err = cos_result.err * fabs((1.0 - a)/x) + sin_result.err * fabs(a);
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result->err += GSL_DBL_EPSILON * (fabs(cx/x) + fabs(sx/(x*x)));
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return GSL_ERROR_SELECT_2(stat_cos, stat_sin);
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}
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}
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int gsl_sf_bessel_yl_e(int l, const double x, gsl_sf_result * result)
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{
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/* CHECK_POINTER(result) */
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if(l < 0 || x <= 0.0) {
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DOMAIN_ERROR(result);
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}
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else if(l == 0) {
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return gsl_sf_bessel_y0_e(x, result);
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}
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else if(l == 1) {
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return gsl_sf_bessel_y1_e(x, result);
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}
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else if(l == 2) {
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return gsl_sf_bessel_y2_e(x, result);
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}
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else if(x < 3.0) {
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return bessel_yl_small_x(l, x, result);
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}
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else if(GSL_ROOT3_DBL_EPSILON * x > (l*l + l + 1.0)) {
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int status = gsl_sf_bessel_Ynu_asympx_e(l + 0.5, x, result);
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double pre = sqrt((0.5*M_PI)/x);
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result->val *= pre;
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result->err *= pre;
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return status;
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}
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else if(l > 40) {
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int status = gsl_sf_bessel_Ynu_asymp_Olver_e(l + 0.5, x, result);
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double pre = sqrt((0.5*M_PI)/x);
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result->val *= pre;
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result->err *= pre;
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return status;
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}
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else {
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/* recurse upward */
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gsl_sf_result r_by;
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gsl_sf_result r_bym;
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int stat_1 = gsl_sf_bessel_y1_e(x, &r_by);
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int stat_0 = gsl_sf_bessel_y0_e(x, &r_bym);
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double bym = r_bym.val;
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double by = r_by.val;
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double byp;
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int j;
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for(j=1; j
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byp = (2*j+1)/x*by - bym;
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bym = by;
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by = byp;
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}
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result->val = by;
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result->err = fabs(result->val) * (GSL_DBL_EPSILON + fabs(r_by.err/r_by.val) + fabs(r_bym.err/r_bym.val));
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return GSL_ERROR_SELECT_2(stat_1, stat_0);
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}
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}
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|
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int gsl_sf_bessel_yl_array(const int lmax, const double x, double * result_array)
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{
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/* CHECK_POINTER(result_array) */
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if(lmax < 0 || x <= 0.0) {
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GSL_ERROR ("error", GSL_EDOM);
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} else if (lmax == 0) {
|
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gsl_sf_result result;
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int stat = gsl_sf_bessel_y0_e(x, &result);
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result_array[0] = result.val;
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return stat;
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} else {
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gsl_sf_result r_yell;
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gsl_sf_result r_yellm1;
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int stat_1 = gsl_sf_bessel_y1_e(x, &r_yell);
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int stat_0 = gsl_sf_bessel_y0_e(x, &r_yellm1);
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double yellp1;
|
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double yell = r_yell.val;
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double yellm1 = r_yellm1.val;
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int ell;
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result_array[0] = yellm1;
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result_array[1] = yell;
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|
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for(ell = 1; ell < lmax; ell++) {
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yellp1 = (2*ell+1)/x * yell - yellm1;
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result_array[ell+1] = yellp1;
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yellm1 = yell;
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yell = yellp1;
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}
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|
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return GSL_ERROR_SELECT_2(stat_0, stat_1);
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}
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}
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|
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|
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/*-*-*-*-*-*-*-*-*-* Functions w/ Natural Prototypes *-*-*-*-*-*-*-*-*-*-*/
|
|
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|
|
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#include "eval.h"
|
|
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|
|
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double gsl_sf_bessel_y0(const double x)
|
|
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{
|
|
Packit |
67cb25 |
EVAL_RESULT(gsl_sf_bessel_y0_e(x, &result));
|
|
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}
|
|
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|
|
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double gsl_sf_bessel_y1(const double x)
|
|
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67cb25 |
{
|
|
Packit |
67cb25 |
EVAL_RESULT(gsl_sf_bessel_y1_e(x, &result));
|
|
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}
|
|
Packit |
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|
|
Packit |
67cb25 |
double gsl_sf_bessel_y2(const double x)
|
|
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{
|
|
Packit |
67cb25 |
EVAL_RESULT(gsl_sf_bessel_y2_e(x, &result));
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|
Packit |
67cb25 |
}
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|
Packit |
67cb25 |
|
|
Packit |
67cb25 |
double gsl_sf_bessel_yl(const int l, const double x)
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|
Packit |
67cb25 |
{
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|
Packit |
67cb25 |
EVAL_RESULT(gsl_sf_bessel_yl_e(l, x, &result));
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|
Packit |
67cb25 |
}
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|
Packit |
67cb25 |
|
|
Packit |
67cb25 |
|