3 * Copyright (C) 1996, 1997, 1998, 1999, 2000 Gerard Jungman
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 3 of the License, or (at
8 * your option) any later version.
10 * This program is distributed in the hope that it will be useful, but
11 * WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * General Public License for more details.
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
20 /* Author: G. Jungman */
21 /* augmented to n=5 and 6 2005-11-08 by R. J. Mathar, http://www.strw.leidenuniv.nl/~mathar */
24 #include <gsl/gsl_math.h>
25 #include <gsl/gsl_errno.h>
26 #include <gsl/gsl_sf_debye.h>
31 #include "chebyshev.h"
32 #include "cheb_eval.c"
34 static double adeb1_data[17] = {
35 2.4006597190381410194,
36 0.1937213042189360089,
37 -0.62329124554895770e-02,
38 0.3511174770206480e-03,
39 -0.228222466701231e-04,
53 static cheb_series adeb1_cs = {
60 static double adeb2_data[18] = {
61 2.5943810232570770282,
62 0.2863357204530719834,
63 -0.102062656158046713e-01,
64 0.6049109775346844e-03,
65 -0.405257658950210e-04,
80 static cheb_series adeb2_cs = {
87 static double adeb3_data[17] = {
90 -0.12945150184440869e-01,
91 0.7963755380173816e-03,
92 -0.546360009590824e-04,
106 static cheb_series adeb3_cs = {
113 static double adeb4_data[17] = {
114 2.781869415020523460,
115 0.374976783526892863,
116 -0.14940907399031583e-01,
117 0.945679811437042e-03,
118 -0.66132916138933e-04,
120 -0.3588083958759e-06,
132 static cheb_series adeb4_cs = {
139 static double adeb5_data[17] = {
140 2.8340269546834530149,
141 0.3994098857106266445,
142 -0.164566764773099646e-1,
143 0.10652138340664541e-2,
144 -0.756730374875418e-4,
158 static cheb_series adeb5_cs = {
165 static double adeb6_data[17] = {
166 2.8726727134130122113,
167 0.4174375352339027746,
168 -0.176453849354067873e-1,
169 0.11629852733494556e-2,
170 -0.837118027357117e-4,
184 static cheb_series adeb6_cs = {
192 /*-*-*-*-*-*-*-*-*-*-*-* Functions with Error Codes *-*-*-*-*-*-*-*-*-*-*-*/
194 int gsl_sf_debye_1_e(const double x, gsl_sf_result * result)
196 const double val_infinity = 1.64493406684822644;
197 const double xcut = -GSL_LOG_DBL_MIN;
199 /* CHECK_POINTER(result) */
202 DOMAIN_ERROR(result);
204 else if(x < 2.0*GSL_SQRT_DBL_EPSILON) {
205 result->val = 1.0 - 0.25*x + x*x/36.0;
206 result->err = GSL_DBL_EPSILON * fabs(result->val);
210 const double t = x*x/8.0 - 1.0;
212 cheb_eval_e(&adeb1_cs, t, &c);
213 result->val = c.val - 0.25 * x;
214 result->err = c.err + 0.25 * x * GSL_DBL_EPSILON;
217 else if(x < -(M_LN2 + GSL_LOG_DBL_EPSILON)) {
218 const int nexp = floor(xcut/x);
219 const double ex = exp(-x);
221 double xk = nexp * x;
224 for(i=nexp; i>=1; i--) {
226 sum += (1.0 + 1.0/xk)/rk;
230 result->val = val_infinity/x - sum*ex;
231 result->err = GSL_DBL_EPSILON * fabs(result->val);
235 result->val = (val_infinity - exp(-x)*(x+1.0)) / x;
236 result->err = GSL_DBL_EPSILON * fabs(result->val);
240 result->val = val_infinity/x;
241 result->err = GSL_DBL_EPSILON * fabs(result->val);
247 int gsl_sf_debye_2_e(const double x, gsl_sf_result * result)
249 const double val_infinity = 4.80822761263837714;
250 const double xcut = -GSL_LOG_DBL_MIN;
252 /* CHECK_POINTER(result) */
255 DOMAIN_ERROR(result);
257 else if(x < 2.0*M_SQRT2*GSL_SQRT_DBL_EPSILON) {
258 result->val = 1.0 - x/3.0 + x*x/24.0;
259 result->err = GSL_DBL_EPSILON * result->val;
263 const double t = x*x/8.0 - 1.0;
265 cheb_eval_e(&adeb2_cs, t, &c);
266 result->val = c.val - x/3.0;
267 result->err = c.err + GSL_DBL_EPSILON * x/3.0;
270 else if(x < -(M_LN2 + GSL_LOG_DBL_EPSILON)) {
271 const int nexp = floor(xcut/x);
272 const double ex = exp(-x);
273 double xk = nexp * x;
277 for(i=nexp; i>=1; i--) {
279 sum += (1.0 + 2.0/xk + 2.0/(xk*xk)) / rk;
283 result->val = val_infinity/(x*x) - 2.0 * sum * ex;
284 result->err = GSL_DBL_EPSILON * fabs(result->val);
288 const double x2 = x*x;
289 const double sum = 2.0 + 2.0*x + x2;
290 result->val = (val_infinity - 2.0 * sum * exp(-x)) / x2;
291 result->err = GSL_DBL_EPSILON * fabs(result->val);
295 result->val = (val_infinity/x)/x;
296 result->err = GSL_DBL_EPSILON * result->val;
297 CHECK_UNDERFLOW(result);
303 int gsl_sf_debye_3_e(const double x, gsl_sf_result * result)
305 const double val_infinity = 19.4818182068004875;
306 const double xcut = -GSL_LOG_DBL_MIN;
308 /* CHECK_POINTER(result) */
311 DOMAIN_ERROR(result);
313 else if(x < 2.0*M_SQRT2*GSL_SQRT_DBL_EPSILON) {
314 result->val = 1.0 - 3.0*x/8.0 + x*x/20.0;
315 result->err = GSL_DBL_EPSILON * result->val;
319 const double t = x*x/8.0 - 1.0;
321 cheb_eval_e(&adeb3_cs, t, &c);
322 result->val = c.val - 0.375*x;
323 result->err = c.err + GSL_DBL_EPSILON * 0.375*x;
326 else if(x < -(M_LN2 + GSL_LOG_DBL_EPSILON)) {
327 const int nexp = floor(xcut/x);
328 const double ex = exp(-x);
329 double xk = nexp * x;
333 for(i=nexp; i>=1; i--) {
334 double xk_inv = 1.0/xk;
336 sum += (((6.0*xk_inv + 6.0)*xk_inv + 3.0)*xk_inv + 1.0) / rk;
340 result->val = val_infinity/(x*x*x) - 3.0 * sum * ex;
341 result->err = GSL_DBL_EPSILON * result->val;
345 const double x3 = x*x*x;
346 const double sum = 6.0 + 6.0*x + 3.0*x*x + x3;
347 result->val = (val_infinity - 3.0 * sum * exp(-x)) / x3;
348 result->err = GSL_DBL_EPSILON * result->val;
352 result->val = ((val_infinity/x)/x)/x;
353 result->err = GSL_DBL_EPSILON * result->val;
354 CHECK_UNDERFLOW(result);
360 int gsl_sf_debye_4_e(const double x, gsl_sf_result * result)
362 const double val_infinity = 99.5450644937635129;
363 const double xcut = -GSL_LOG_DBL_MIN;
365 /* CHECK_POINTER(result) */
368 DOMAIN_ERROR(result);
370 else if(x < 2.0*M_SQRT2*GSL_SQRT_DBL_EPSILON) {
371 result->val = 1.0 - 2.0*x/5.0 + x*x/18.0;
372 result->err = GSL_DBL_EPSILON * result->val;
376 const double t = x*x/8.0 - 1.0;
378 cheb_eval_e(&adeb4_cs, t, &c);
379 result->val = c.val - 2.0*x/5.0;
380 result->err = c.err + GSL_DBL_EPSILON * 2.0*x/5.0;
383 else if(x < -(M_LN2 + GSL_LOG_DBL_EPSILON)) {
384 const int nexp = floor(xcut/x);
385 const double ex = exp(-x);
386 double xk = nexp * x;
390 for(i=nexp; i>=1; i--) {
391 double xk_inv = 1.0/xk;
393 sum += ((((24.0*xk_inv + 24.0)*xk_inv + 12.0)*xk_inv + 4.0)*xk_inv + 1.0) / rk;
397 result->val = val_infinity/(x*x*x*x) - 4.0 * sum * ex;
398 result->err = GSL_DBL_EPSILON * result->val;
402 const double x2 = x*x;
403 const double x4 = x2*x2;
404 const double sum = 24.0 + 24.0*x + 12.0*x2 + 4.0*x2*x + x4;
405 result->val = (val_infinity - 4.0 * sum * exp(-x)) / x4;
406 result->err = GSL_DBL_EPSILON * result->val;
410 result->val = (((val_infinity/x)/x)/x)/x;
411 result->err = GSL_DBL_EPSILON * result->val;
412 CHECK_UNDERFLOW(result);
417 int gsl_sf_debye_5_e(const double x, gsl_sf_result * result)
419 const double val_infinity = 610.405837190669483828710757875 ;
420 const double xcut = -GSL_LOG_DBL_MIN;
422 /* CHECK_POINTER(result) */
425 DOMAIN_ERROR(result);
427 else if(x < 2.0*M_SQRT2*GSL_SQRT_DBL_EPSILON) {
428 result->val = 1.0 - 5.0*x/12.0 + 5.0*x*x/84.0;
429 result->err = GSL_DBL_EPSILON * result->val;
433 const double t = x*x/8.0 - 1.0;
435 cheb_eval_e(&adeb5_cs, t, &c);
436 result->val = c.val - 5.0*x/12.0;
437 result->err = c.err + GSL_DBL_EPSILON * 5.0*x/12.0;
440 else if(x < -(M_LN2 + GSL_LOG_DBL_EPSILON)) {
441 const int nexp = floor(xcut/x);
442 const double ex = exp(-x);
443 double xk = nexp * x;
447 for(i=nexp; i>=1; i--) {
448 double xk_inv = 1.0/xk;
450 sum += (((((120.0*xk_inv + 120.0)*xk_inv + 60.0)*xk_inv + 20.0)*xk_inv + 5.0)*xk_inv+ 1.0) / rk;
454 result->val = val_infinity/(x*x*x*x*x) - 5.0 * sum * ex;
455 result->err = GSL_DBL_EPSILON * result->val;
459 const double x2 = x*x;
460 const double x4 = x2*x2;
461 const double x5 = x4*x;
462 const double sum = 120.0 + 120.0*x + 60.0*x2 + 20.0*x2*x + 5.0*x4 + x5;
463 result->val = (val_infinity - 5.0 * sum * exp(-x)) / x5;
464 result->err = GSL_DBL_EPSILON * result->val;
468 result->val = ((((val_infinity/x)/x)/x)/x)/x;
469 result->err = GSL_DBL_EPSILON * result->val;
470 CHECK_UNDERFLOW(result);
475 int gsl_sf_debye_6_e(const double x, gsl_sf_result * result)
477 const double val_infinity = 4356.06887828990661194792541535 ;
478 const double xcut = -GSL_LOG_DBL_MIN;
480 /* CHECK_POINTER(result) */
483 DOMAIN_ERROR(result);
485 else if(x < 2.0*M_SQRT2*GSL_SQRT_DBL_EPSILON) {
486 result->val = 1.0 - 3.0*x/7.0 + x*x/16.0;
487 result->err = GSL_DBL_EPSILON * result->val;
491 const double t = x*x/8.0 - 1.0;
493 cheb_eval_e(&adeb6_cs, t, &c);
494 result->val = c.val - 3.0*x/7.0;
495 result->err = c.err + GSL_DBL_EPSILON * 3.0*x/7.0;
498 else if(x < -(M_LN2 + GSL_LOG_DBL_EPSILON)) {
499 const int nexp = floor(xcut/x);
500 const double ex = exp(-x);
501 double xk = nexp * x;
505 for(i=nexp; i>=1; i--) {
506 double xk_inv = 1.0/xk;
508 sum += ((((((720.0*xk_inv + 720.0)*xk_inv + 360.0)*xk_inv + 120.0)*xk_inv + 30.0)*xk_inv+ 6.0)*xk_inv+ 1.0) / rk;
512 result->val = val_infinity/(x*x*x*x*x*x) - 6.0 * sum * ex;
513 result->err = GSL_DBL_EPSILON * result->val;
517 const double x2 = x*x;
518 const double x4 = x2*x2;
519 const double x6 = x4*x2;
520 const double sum = 720.0 + 720.0*x + 360.0*x2 + 120.0*x2*x + 30.0*x4 + 6.0*x4*x +x6 ;
521 result->val = (val_infinity - 6.0 * sum * exp(-x)) / x6;
522 result->err = GSL_DBL_EPSILON * result->val;
526 result->val = (((((val_infinity/x)/x)/x)/x)/x)/x ;
527 result->err = GSL_DBL_EPSILON * result->val;
528 CHECK_UNDERFLOW(result);
534 /*-*-*-*-*-*-*-*-*-* Functions w/ Natural Prototypes *-*-*-*-*-*-*-*-*-*-*/
538 double gsl_sf_debye_1(const double x)
540 EVAL_RESULT(gsl_sf_debye_1_e(x, &result));
543 double gsl_sf_debye_2(const double x)
545 EVAL_RESULT(gsl_sf_debye_2_e(x, &result));
548 double gsl_sf_debye_3(const double x)
550 EVAL_RESULT(gsl_sf_debye_3_e(x, &result));
553 double gsl_sf_debye_4(const double x)
555 EVAL_RESULT(gsl_sf_debye_4_e(x, &result));
558 double gsl_sf_debye_5(const double x)
560 EVAL_RESULT(gsl_sf_debye_5_e(x, &result));
563 double gsl_sf_debye_6(const double x)
565 EVAL_RESULT(gsl_sf_debye_6_e(x, &result));