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 */
23 #include <gsl/gsl_math.h>
24 #include <gsl/gsl_errno.h>
25 #include <gsl/gsl_sf_log.h>
26 #include <gsl/gsl_sf_trig.h>
30 #include "chebyshev.h"
31 #include "cheb_eval.c"
34 * double-precision for |x| < 1.0
39 sinh_series(const double x, double * result)
42 const double c0 = 1.0/6.0;
43 const double c1 = 1.0/120.0;
44 const double c2 = 1.0/5040.0;
45 const double c3 = 1.0/362880.0;
46 const double c4 = 1.0/39916800.0;
47 const double c5 = 1.0/6227020800.0;
48 const double c6 = 1.0/1307674368000.0;
49 const double c7 = 1.0/355687428096000.0;
50 *result = x*(1.0 + y*(c0+y*(c1+y*(c2+y*(c3+y*(c4+y*(c5+y*(c6+y*c7))))))));
56 * double-precision for |x| < 1.0
61 cosh_m1_series(const double x, double * result)
64 const double c0 = 0.5;
65 const double c1 = 1.0/24.0;
66 const double c2 = 1.0/720.0;
67 const double c3 = 1.0/40320.0;
68 const double c4 = 1.0/3628800.0;
69 const double c5 = 1.0/479001600.0;
70 const double c6 = 1.0/87178291200.0;
71 const double c7 = 1.0/20922789888000.0;
72 const double c8 = 1.0/6402373705728000.0;
73 *result = y*(c0+y*(c1+y*(c2+y*(c3+y*(c4+y*(c5+y*(c6+y*(c7+y*c8))))))));
78 /* Chebyshev expansion for f(t) = sinc((t+1)/2), -1 < t < 1
80 static double sinc_data[17] = {
81 1.133648177811747875422,
82 -0.532677564732557348781,
83 -0.068293048346633177859,
84 0.033403684226353715020,
85 0.001485679893925747818,
86 -0.000734421305768455295,
87 -0.000016837282388837229,
88 0.000008359950146618018,
89 0.000000117382095601192,
90 -0.000000058413665922724,
91 -0.000000000554763755743,
92 0.000000000276434190426,
93 0.000000000001895374892,
94 -0.000000000000945237101,
95 -0.000000000000004900690,
96 0.000000000000002445383,
97 0.000000000000000009925
99 static cheb_series sinc_cs = {
107 /* Chebyshev expansion for f(t) = g((t+1)Pi/8), -1<t<1
108 * g(x) = (sin(x)/x - 1)/(x*x)
110 static double sin_data[12] = {
111 -0.3295190160663511504173,
112 0.0025374284671667991990,
113 0.0006261928782647355874,
114 -4.6495547521854042157541e-06,
115 -5.6917531549379706526677e-07,
116 3.7283335140973803627866e-09,
117 3.0267376484747473727186e-10,
118 -1.7400875016436622322022e-12,
119 -1.0554678305790849834462e-13,
120 5.3701981409132410797062e-16,
121 2.5984137983099020336115e-17,
122 -1.1821555255364833468288e-19
124 static cheb_series sin_cs = {
131 /* Chebyshev expansion for f(t) = g((t+1)Pi/8), -1<t<1
132 * g(x) = (2(cos(x) - 1)/(x^2) + 1) / x^2
134 static double cos_data[11] = {
135 0.165391825637921473505668118136,
136 -0.00084852883845000173671196530195,
137 -0.000210086507222940730213625768083,
138 1.16582269619760204299639757584e-6,
139 1.43319375856259870334412701165e-7,
140 -7.4770883429007141617951330184e-10,
141 -6.0969994944584252706997438007e-11,
142 2.90748249201909353949854872638e-13,
143 1.77126739876261435667156490461e-14,
144 -7.6896421502815579078577263149e-17,
145 -3.7363121133079412079201377318e-18
147 static cheb_series cos_cs = {
155 /*-*-*-*-*-*-*-*-*-*-*-* Functions with Error Codes *-*-*-*-*-*-*-*-*-*-*-*/
157 /* I would have prefered just using the library sin() function.
158 * But after some experimentation I decided that there was
159 * no good way to understand the error; library sin() is just a black box.
160 * So we have to roll our own.
163 gsl_sf_sin_e(double x, gsl_sf_result * result)
165 /* CHECK_POINTER(result) */
168 const double P1 = 7.85398125648498535156e-1;
169 const double P2 = 3.77489470793079817668e-8;
170 const double P3 = 2.69515142907905952645e-15;
172 const double sgn_x = GSL_SIGN(x);
173 const double abs_x = fabs(x);
175 if(abs_x < GSL_ROOT4_DBL_EPSILON) {
176 const double x2 = x*x;
177 result->val = x * (1.0 - x2/6.0);
178 result->err = fabs(x*x2*x2 / 100.0);
182 double sgn_result = sgn_x;
183 double y = floor(abs_x/(0.25*M_PI));
184 int octant = y - ldexp(floor(ldexp(y,-3)),3);
188 if(GSL_IS_ODD(octant)) {
196 sgn_result = -sgn_result;
199 z = ((abs_x - y * P1) - y * P2) - y * P3;
202 gsl_sf_result sin_cs_result;
203 const double t = 8.0*fabs(z)/M_PI - 1.0;
204 stat_cs = cheb_eval_e(&sin_cs, t, &sin_cs_result);
205 result->val = z * (1.0 + z*z * sin_cs_result.val);
207 else { /* octant == 2 */
208 gsl_sf_result cos_cs_result;
209 const double t = 8.0*fabs(z)/M_PI - 1.0;
210 stat_cs = cheb_eval_e(&cos_cs, t, &cos_cs_result);
211 result->val = 1.0 - 0.5*z*z * (1.0 - z*z * cos_cs_result.val);
214 result->val *= sgn_result;
216 if(abs_x > 1.0/GSL_DBL_EPSILON) {
217 result->err = fabs(result->val);
219 else if(abs_x > 100.0/GSL_SQRT_DBL_EPSILON) {
220 result->err = 2.0 * abs_x * GSL_DBL_EPSILON * fabs(result->val);
222 else if(abs_x > 0.1/GSL_SQRT_DBL_EPSILON) {
223 result->err = 2.0 * GSL_SQRT_DBL_EPSILON * fabs(result->val);
226 result->err = 2.0 * GSL_DBL_EPSILON * fabs(result->val);
236 gsl_sf_cos_e(double x, gsl_sf_result * result)
238 /* CHECK_POINTER(result) */
241 const double P1 = 7.85398125648498535156e-1;
242 const double P2 = 3.77489470793079817668e-8;
243 const double P3 = 2.69515142907905952645e-15;
245 const double abs_x = fabs(x);
247 if(abs_x < GSL_ROOT4_DBL_EPSILON) {
248 const double x2 = x*x;
249 result->val = 1.0 - 0.5*x2;
250 result->err = fabs(x2*x2/12.0);
254 double sgn_result = 1.0;
255 double y = floor(abs_x/(0.25*M_PI));
256 int octant = y - ldexp(floor(ldexp(y,-3)),3);
260 if(GSL_IS_ODD(octant)) {
268 sgn_result = -sgn_result;
272 sgn_result = -sgn_result;
275 z = ((abs_x - y * P1) - y * P2) - y * P3;
278 gsl_sf_result cos_cs_result;
279 const double t = 8.0*fabs(z)/M_PI - 1.0;
280 stat_cs = cheb_eval_e(&cos_cs, t, &cos_cs_result);
281 result->val = 1.0 - 0.5*z*z * (1.0 - z*z * cos_cs_result.val);
283 else { /* octant == 2 */
284 gsl_sf_result sin_cs_result;
285 const double t = 8.0*fabs(z)/M_PI - 1.0;
286 stat_cs = cheb_eval_e(&sin_cs, t, &sin_cs_result);
287 result->val = z * (1.0 + z*z * sin_cs_result.val);
290 result->val *= sgn_result;
292 if(abs_x > 1.0/GSL_DBL_EPSILON) {
293 result->err = fabs(result->val);
295 else if(abs_x > 100.0/GSL_SQRT_DBL_EPSILON) {
296 result->err = 2.0 * abs_x * GSL_DBL_EPSILON * fabs(result->val);
298 else if(abs_x > 0.1/GSL_SQRT_DBL_EPSILON) {
299 result->err = 2.0 * GSL_SQRT_DBL_EPSILON * fabs(result->val);
302 result->err = 2.0 * GSL_DBL_EPSILON * fabs(result->val);
312 gsl_sf_hypot_e(const double x, const double y, gsl_sf_result * result)
314 /* CHECK_POINTER(result) */
316 if(x == 0.0 && y == 0.0) {
322 const double a = fabs(x);
323 const double b = fabs(y);
324 const double min = GSL_MIN_DBL(a,b);
325 const double max = GSL_MAX_DBL(a,b);
326 const double rat = min/max;
327 const double root_term = sqrt(1.0 + rat*rat);
329 if(max < GSL_DBL_MAX/root_term) {
330 result->val = max * root_term;
331 result->err = 2.0 * GSL_DBL_EPSILON * fabs(result->val);
335 OVERFLOW_ERROR(result);
342 gsl_sf_complex_sin_e(const double zr, const double zi,
343 gsl_sf_result * szr, gsl_sf_result * szi)
345 /* CHECK_POINTER(szr) */
346 /* CHECK_POINTER(szi) */
350 sinh_series(zi, &sh);
351 cosh_m1_series(zi, &ch_m1);
352 szr->val = sin(zr)*(ch_m1 + 1.0);
353 szi->val = cos(zr)*sh;
354 szr->err = 2.0 * GSL_DBL_EPSILON * fabs(szr->val);
355 szi->err = 2.0 * GSL_DBL_EPSILON * fabs(szi->val);
358 else if(fabs(zi) < GSL_LOG_DBL_MAX) {
360 double ch = 0.5*(ex+1.0/ex);
361 double sh = 0.5*(ex-1.0/ex);
362 szr->val = sin(zr)*ch;
363 szi->val = cos(zr)*sh;
364 szr->err = 2.0 * GSL_DBL_EPSILON * fabs(szr->val);
365 szi->err = 2.0 * GSL_DBL_EPSILON * fabs(szi->val);
369 OVERFLOW_ERROR_2(szr, szi);
375 gsl_sf_complex_cos_e(const double zr, const double zi,
376 gsl_sf_result * czr, gsl_sf_result * czi)
378 /* CHECK_POINTER(czr) */
379 /* CHECK_POINTER(czi) */
383 sinh_series(zi, &sh);
384 cosh_m1_series(zi, &ch_m1);
385 czr->val = cos(zr)*(ch_m1 + 1.0);
386 czi->val = -sin(zr)*sh;
387 czr->err = 2.0 * GSL_DBL_EPSILON * fabs(czr->val);
388 czi->err = 2.0 * GSL_DBL_EPSILON * fabs(czi->val);
391 else if(fabs(zi) < GSL_LOG_DBL_MAX) {
393 double ch = 0.5*(ex+1.0/ex);
394 double sh = 0.5*(ex-1.0/ex);
395 czr->val = cos(zr)*ch;
396 czi->val = -sin(zr)*sh;
397 czr->err = 2.0 * GSL_DBL_EPSILON * fabs(czr->val);
398 czi->err = 2.0 * GSL_DBL_EPSILON * fabs(czi->val);
402 OVERFLOW_ERROR_2(czr,czi);
408 gsl_sf_complex_logsin_e(const double zr, const double zi,
409 gsl_sf_result * lszr, gsl_sf_result * lszi)
411 /* CHECK_POINTER(lszr) */
412 /* CHECK_POINTER(lszi) */
415 lszr->val = -M_LN2 + zi;
416 lszi->val = 0.5*M_PI - zr;
417 lszr->err = 2.0 * GSL_DBL_EPSILON * fabs(lszr->val);
418 lszi->err = 2.0 * GSL_DBL_EPSILON * fabs(lszi->val);
420 else if(zi < -60.0) {
421 lszr->val = -M_LN2 - zi;
422 lszi->val = -0.5*M_PI + zr;
423 lszr->err = 2.0 * GSL_DBL_EPSILON * fabs(lszr->val);
424 lszi->err = 2.0 * GSL_DBL_EPSILON * fabs(lszi->val);
427 gsl_sf_result sin_r, sin_i;
429 gsl_sf_complex_sin_e(zr, zi, &sin_r, &sin_i); /* ok by construction */
430 status = gsl_sf_complex_log_e(sin_r.val, sin_i.val, lszr, lszi);
431 if(status == GSL_EDOM) {
432 DOMAIN_ERROR_2(lszr, lszi);
435 return gsl_sf_angle_restrict_symm_e(&(lszi->val));
440 gsl_sf_lnsinh_e(const double x, gsl_sf_result * result)
442 /* CHECK_POINTER(result) */
445 DOMAIN_ERROR(result);
447 else if(fabs(x) < 1.0) {
449 sinh_series(x, &eps);
450 result->val = log(eps);
451 result->err = 2.0 * GSL_DBL_EPSILON * fabs(result->val);
454 else if(x < -0.5*GSL_LOG_DBL_EPSILON) {
455 result->val = x + log(0.5*(1.0 - exp(-2.0*x)));
456 result->err = 2.0 * GSL_DBL_EPSILON * fabs(result->val);
460 result->val = -M_LN2 + x;
461 result->err = 2.0 * GSL_DBL_EPSILON * fabs(result->val);
467 int gsl_sf_lncosh_e(const double x, gsl_sf_result * result)
469 /* CHECK_POINTER(result) */
473 cosh_m1_series(x, &eps);
474 return gsl_sf_log_1plusx_e(eps, result);
476 else if(x < -0.5*GSL_LOG_DBL_EPSILON) {
477 result->val = x + log(0.5*(1.0 + exp(-2.0*x)));
478 result->err = 2.0 * GSL_DBL_EPSILON * fabs(result->val);
482 result->val = -M_LN2 + x;
483 result->err = 2.0 * GSL_DBL_EPSILON * fabs(result->val);
490 inline int gsl_sf_sincos_e(const double theta, double * s, double * c)
492 double tan_half = tan(0.5 * theta);
493 double den = 1. + tan_half*tan_half;
494 double cos_theta = (1.0 - tan_half*tan_half) / den;
495 double sin_theta = 2.0 * tan_half / den;
500 gsl_sf_polar_to_rect(const double r, const double theta,
501 gsl_sf_result * x, gsl_sf_result * y)
504 int status = gsl_sf_angle_restrict_symm_e(&t);
509 x->err = r * fabs(s * GSL_DBL_EPSILON * t);
510 x->err += 2.0 * GSL_DBL_EPSILON * fabs(x->val);
511 y->err = r * fabs(c * GSL_DBL_EPSILON * t);
512 y->err += 2.0 * GSL_DBL_EPSILON * fabs(y->val);
518 gsl_sf_rect_to_polar(const double x, const double y,
519 gsl_sf_result * r, gsl_sf_result * theta)
521 int stat_h = gsl_sf_hypot_e(x, y, r);
523 theta->val = atan2(y, x);
524 theta->err = 2.0 * GSL_DBL_EPSILON * fabs(theta->val);
533 int gsl_sf_angle_restrict_symm_err_e(const double theta, gsl_sf_result * result)
535 /* synthetic extended precision constants */
536 const double P1 = 4 * 7.8539812564849853515625e-01;
537 const double P2 = 4 * 3.7748947079307981766760e-08;
538 const double P3 = 4 * 2.6951514290790594840552e-15;
539 const double TwoPi = 2*(P1 + P2 + P3);
541 const double y = GSL_SIGN(theta) * 2 * floor(fabs(theta)/TwoPi);
542 double r = ((theta - y*P1) - y*P2) - y*P3;
544 if(r > M_PI) { r = (((r-2*P1)-2*P2)-2*P3); } /* r-TwoPi */
545 else if (r < -M_PI) r = (((r+2*P1)+2*P2)+2*P3); /* r+TwoPi */
549 if(fabs(theta) > 0.0625/GSL_DBL_EPSILON) {
550 result->val = GSL_NAN;
551 result->err = GSL_NAN;
552 GSL_ERROR ("error", GSL_ELOSS);
554 else if(fabs(theta) > 0.0625/GSL_SQRT_DBL_EPSILON) {
555 result->err = 2.0 * GSL_DBL_EPSILON * fabs(result->val - theta);
559 double delta = fabs(result->val - theta);
560 result->err = 2.0 * GSL_DBL_EPSILON * ((delta < M_PI) ? delta : M_PI);
566 int gsl_sf_angle_restrict_pos_err_e(const double theta, gsl_sf_result * result)
568 /* synthetic extended precision constants */
569 const double P1 = 4 * 7.85398125648498535156e-01;
570 const double P2 = 4 * 3.77489470793079817668e-08;
571 const double P3 = 4 * 2.69515142907905952645e-15;
572 const double TwoPi = 2*(P1 + P2 + P3);
574 const double y = 2*floor(theta/TwoPi);
576 double r = ((theta - y*P1) - y*P2) - y*P3;
578 if(r > TwoPi) {r = (((r-2*P1)-2*P2)-2*P3); } /* r-TwoPi */
579 else if (r < 0) { /* may happen due to FP rounding */
580 r = (((r+2*P1)+2*P2)+2*P3); /* r+TwoPi */
585 if(fabs(theta) > 0.0625/GSL_DBL_EPSILON) {
586 result->val = GSL_NAN;
587 result->err = fabs(result->val);
588 GSL_ERROR ("error", GSL_ELOSS);
590 else if(fabs(theta) > 0.0625/GSL_SQRT_DBL_EPSILON) {
591 result->err = GSL_DBL_EPSILON * fabs(result->val - theta);
595 double delta = fabs(result->val - theta);
596 result->err = 2.0 * GSL_DBL_EPSILON * ((delta < M_PI) ? delta : M_PI);
602 int gsl_sf_angle_restrict_symm_e(double * theta)
605 int stat = gsl_sf_angle_restrict_symm_err_e(*theta, &r);
611 int gsl_sf_angle_restrict_pos_e(double * theta)
614 int stat = gsl_sf_angle_restrict_pos_err_e(*theta, &r);
620 int gsl_sf_sin_err_e(const double x, const double dx, gsl_sf_result * result)
622 int stat_s = gsl_sf_sin_e(x, result);
623 result->err += fabs(cos(x) * dx);
624 result->err += GSL_DBL_EPSILON * fabs(result->val);
629 int gsl_sf_cos_err_e(const double x, const double dx, gsl_sf_result * result)
631 int stat_c = gsl_sf_cos_e(x, result);
632 result->err += fabs(sin(x) * dx);
633 result->err += GSL_DBL_EPSILON * fabs(result->val);
640 gsl_sf_sin_pi_x_e(const double x, gsl_sf_result * result)
642 /* CHECK_POINTER(result) */
644 if(-100.0 < x && x < 100.0) {
645 result->val = sin(M_PI * x) / (M_PI * x);
646 result->err = 2.0 * GSL_DBL_EPSILON * fabs(result->val);
650 const double N = floor(x + 0.5);
651 const double f = x - N;
653 if(N < INT_MAX && N > INT_MIN) {
654 /* Make it an integer if we can. Saves another
657 const int intN = (int)N;
658 const double sign = ( GSL_IS_ODD(intN) ? -1.0 : 1.0 );
659 result->val = sign * sin(M_PI * f);
660 result->err = GSL_DBL_EPSILON * fabs(result->val);
662 else if(N > 2.0/GSL_DBL_EPSILON || N < -2.0/GSL_DBL_EPSILON) {
663 /* All integer-valued floating point numbers
664 * bigger than 2/eps=2^53 are actually even.
670 const double resN = N - 2.0*floor(0.5*N); /* 0 for even N, 1 for odd N */
671 const double sign = ( fabs(resN) > 0.5 ? -1.0 : 1.0 );
672 result->val = sign * sin(M_PI*f);
673 result->err = GSL_DBL_EPSILON * fabs(result->val);
682 int gsl_sf_sinc_e(double x, gsl_sf_result * result)
684 /* CHECK_POINTER(result) */
687 const double ax = fabs(x);
690 /* Do not go to the limit of the fit since
691 * there is a zero there and the Chebyshev
692 * accuracy will go to zero.
694 return cheb_eval_e(&sinc_cs, 2.0*ax-1.0, result);
696 else if(ax < 100.0) {
697 /* Small arguments are no problem.
698 * We trust the library sin() to
699 * roughly machine precision.
701 result->val = sin(M_PI * ax)/(M_PI * ax);
702 result->err = 2.0 * GSL_DBL_EPSILON * fabs(result->val);
706 /* Large arguments must be handled separately.
708 const double r = M_PI*ax;
710 int stat_s = gsl_sf_sin_e(r, &s);
711 result->val = s.val/r;
712 result->err = s.err/r + 2.0 * GSL_DBL_EPSILON * fabs(result->val);
720 /*-*-*-*-*-*-*-*-*-* Functions w/ Natural Prototypes *-*-*-*-*-*-*-*-*-*-*/
724 double gsl_sf_sin(const double x)
726 EVAL_RESULT(gsl_sf_sin_e(x, &result));
729 double gsl_sf_cos(const double x)
731 EVAL_RESULT(gsl_sf_cos_e(x, &result));
734 double gsl_sf_hypot(const double x, const double y)
736 EVAL_RESULT(gsl_sf_hypot_e(x, y, &result));
739 double gsl_sf_lnsinh(const double x)
741 EVAL_RESULT(gsl_sf_lnsinh_e(x, &result));
744 double gsl_sf_lncosh(const double x)
746 EVAL_RESULT(gsl_sf_lncosh_e(x, &result));
749 double gsl_sf_angle_restrict_symm(const double theta)
751 double result = theta;
752 EVAL_DOUBLE(gsl_sf_angle_restrict_symm_e(&result));
755 double gsl_sf_angle_restrict_pos(const double theta)
757 double result = theta;
758 EVAL_DOUBLE(gsl_sf_angle_restrict_pos_e(&result));
762 double gsl_sf_sin_pi_x(const double x)
764 EVAL_RESULT(gsl_sf_sin_pi_x_e(x, &result));
768 double gsl_sf_sinc(const double x)
770 EVAL_RESULT(gsl_sf_sinc_e(x, &result));