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- /* specfunc/bessel_Y0.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 3 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 "gsl__config.h"
- #include "gsl_math.h"
- #include "gsl_errno.h"
- #include "gsl_sf_trig.h"
- #include "gsl_sf_bessel.h"
- #include "gsl_specfunc__error.h"
- #include "gsl_specfunc__bessel.h"
- #include "gsl_specfunc__bessel_amp_phase.h"
- #include "gsl_specfunc__cheb_eval.c"
- /*-*-*-*-*-*-*-*-*-*-*-* Private Section *-*-*-*-*-*-*-*-*-*-*-*/
- /* based on SLATEC besy0, 1980 version, w. fullerton */
- /* chebyshev expansions
- series for by0 on the interval 0. to 1.60000d+01
- with weighted error 1.20e-17
- log weighted error 16.92
- significant figures required 16.15
- decimal places required 17.48
- */
- static double by0_data[13] = {
- -0.011277839392865573,
- -0.128345237560420350,
- -0.104378847997942490,
- 0.023662749183969695,
- -0.002090391647700486,
- 0.000103975453939057,
- -0.000003369747162423,
- 0.000000077293842676,
- -0.000000001324976772,
- 0.000000000017648232,
- -0.000000000000188105,
- 0.000000000000001641,
- -0.000000000000000011
- };
- static cheb_series by0_cs = {
- by0_data,
- 12,
- -1, 1,
- 8
- };
- /*-*-*-*-*-*-*-*-*-*-*-* Functions with Error Codes *-*-*-*-*-*-*-*-*-*-*-*/
- int gsl_sf_bessel_Y0_e(const double x, gsl_sf_result * result)
- {
- const double two_over_pi = 2.0/M_PI;
- const double xmax = 1.0/GSL_DBL_EPSILON;
- /* CHECK_POINTER(result) */
- if (x <= 0.0) {
- DOMAIN_ERROR(result);
- }
- else if(x < 4.0) {
- gsl_sf_result J0;
- gsl_sf_result c;
- int stat_J0 = gsl_sf_bessel_J0_e(x, &J0);
- cheb_eval_e(&by0_cs, 0.125*x*x-1.0, &c);
- result->val = two_over_pi*(-M_LN2 + log(x))*J0.val + 0.375 + c.val;
- result->err = 2.0 * GSL_DBL_EPSILON * fabs(result->val) + c.err;
- return stat_J0;
- }
- else if(x < xmax) {
- /* Leading behaviour of phase is x, which is exact,
- * so the error is bounded.
- */
- const double z = 32.0/(x*x) - 1.0;
- gsl_sf_result c1;
- gsl_sf_result c2;
- gsl_sf_result sp;
- const int stat_c1 = cheb_eval_e(&_gsl_sf_bessel_amp_phase_bm0_cs, z, &c1);
- const int stat_c2 = cheb_eval_e(&_gsl_sf_bessel_amp_phase_bth0_cs, z, &c2);
- const int stat_sp = gsl_sf_bessel_sin_pi4_e(x, c2.val/x, &sp);
- const double sqrtx = sqrt(x);
- const double ampl = (0.75 + c1.val) / sqrtx;
- result->val = ampl * sp.val;
- result->err = fabs(sp.val) * c1.err/sqrtx + fabs(ampl) * sp.err;
- result->err += 2.0 * GSL_DBL_EPSILON * fabs(result->val);
- return GSL_ERROR_SELECT_3(stat_sp, stat_c1, stat_c2);
- }
- else {
- UNDERFLOW_ERROR(result);
- }
- }
- /*-*-*-*-*-*-*-*-*-* Functions w/ Natural Prototypes *-*-*-*-*-*-*-*-*-*-*/
- #include "gsl_specfunc__eval.h"
- double gsl_sf_bessel_Y0(const double x)
- {
- EVAL_RESULT(gsl_sf_bessel_Y0_e(x, &result));
- }
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