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- /* specfunc/clausen.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_clausen.h"
- #include "gsl_specfunc__chebyshev.h"
- #include "gsl_specfunc__cheb_eval.c"
- static double aclaus_data[15] = {
- 2.142694363766688447e+00,
- 0.723324281221257925e-01,
- 0.101642475021151164e-02,
- 0.3245250328531645e-04,
- 0.133315187571472e-05,
- 0.6213240591653e-07,
- 0.313004135337e-08,
- 0.16635723056e-09,
- 0.919659293e-11,
- 0.52400462e-12,
- 0.3058040e-13,
- 0.18197e-14,
- 0.1100e-15,
- 0.68e-17,
- 0.4e-18
- };
- static cheb_series aclaus_cs = {
- aclaus_data,
- 14,
- -1, 1,
- 8 /* FIXME: this is a guess, correct value needed here BJG */
- };
- /*-*-*-*-*-*-*-*-*-*-*-* Functions with Error Codes *-*-*-*-*-*-*-*-*-*-*-*/
- int gsl_sf_clausen_e(double x, gsl_sf_result *result)
- {
- const double x_cut = M_PI * GSL_SQRT_DBL_EPSILON;
- double sgn = 1.0;
- int status_red;
- if(x < 0.0) {
- x = -x;
- sgn = -1.0;
- }
- /* Argument reduction to [0, 2pi) */
- status_red = gsl_sf_angle_restrict_pos_e(&x);
- /* Further reduction to [0,pi) */
- if(x > M_PI) {
- /* simulated extra precision: 2PI = p0 + p1 */
- const double p0 = 6.28125;
- const double p1 = 0.19353071795864769253e-02;
- x = (p0 - x) + p1;
- sgn = -sgn;
- }
- if(x == 0.0) {
- result->val = 0.0;
- result->err = 0.0;
- }
- else if(x < x_cut) {
- result->val = x * (1.0 - log(x));
- result->err = x * GSL_DBL_EPSILON;
- }
- else {
- const double t = 2.0*(x*x / (M_PI*M_PI) - 0.5);
- gsl_sf_result result_c;
- cheb_eval_e(&aclaus_cs, t, &result_c);
- result->val = x * (result_c.val - log(x));
- result->err = x * (result_c.err + GSL_DBL_EPSILON);
- }
- result->val *= sgn;
- return status_red;
- }
- /*-*-*-*-*-*-*-*-*-* Functions w/ Natural Prototypes *-*-*-*-*-*-*-*-*-*-*/
- #include "gsl_specfunc__eval.h"
- double gsl_sf_clausen(const double x)
- {
- EVAL_RESULT(gsl_sf_clausen_e(x, &result));
- }
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