Update miscellaneous files from upstream sources.
[glibc.git] / sysdeps / ieee754 / ldbl-128 / s_erfl.c
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1 /*
2 * ====================================================
3 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
5 * Developed at SunPro, a Sun Microsystems, Inc. business.
6 * Permission to use, copy, modify, and distribute this
7 * software is freely granted, provided that this notice
8 * is preserved.
9 * ====================================================
12 /* Modifications and expansions for 128-bit long double are
13 Copyright (C) 2001 Stephen L. Moshier <moshier@na-net.ornl.gov>
14 and are incorporated herein by permission of the author. The author
15 reserves the right to distribute this material elsewhere under different
16 copying permissions. These modifications are distributed here under
17 the following terms:
19 This library is free software; you can redistribute it and/or
20 modify it under the terms of the GNU Lesser General Public
21 License as published by the Free Software Foundation; either
22 version 2.1 of the License, or (at your option) any later version.
24 This library is distributed in the hope that it will be useful,
25 but WITHOUT ANY WARRANTY; without even the implied warranty of
26 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
27 Lesser General Public License for more details.
29 You should have received a copy of the GNU Lesser General Public
30 License along with this library; if not, see
31 <http://www.gnu.org/licenses/>. */
33 /* double erf(double x)
34 * double erfc(double x)
35 * x
36 * 2 |\
37 * erf(x) = --------- | exp(-t*t)dt
38 * sqrt(pi) \|
39 * 0
41 * erfc(x) = 1-erf(x)
42 * Note that
43 * erf(-x) = -erf(x)
44 * erfc(-x) = 2 - erfc(x)
46 * Method:
47 * 1. erf(x) = x + x*R(x^2) for |x| in [0, 7/8]
48 * Remark. The formula is derived by noting
49 * erf(x) = (2/sqrt(pi))*(x - x^3/3 + x^5/10 - x^7/42 + ....)
50 * and that
51 * 2/sqrt(pi) = 1.128379167095512573896158903121545171688
52 * is close to one.
54 * 1a. erf(x) = 1 - erfc(x), for |x| > 1.0
55 * erfc(x) = 1 - erf(x) if |x| < 1/4
57 * 2. For |x| in [7/8, 1], let s = |x| - 1, and
58 * c = 0.84506291151 rounded to single (24 bits)
59 * erf(s + c) = sign(x) * (c + P1(s)/Q1(s))
60 * Remark: here we use the taylor series expansion at x=1.
61 * erf(1+s) = erf(1) + s*Poly(s)
62 * = 0.845.. + P1(s)/Q1(s)
63 * Note that |P1/Q1|< 0.078 for x in [0.84375,1.25]
65 * 3. For x in [1/4, 5/4],
66 * erfc(s + const) = erfc(const) + s P1(s)/Q1(s)
67 * for const = 1/4, 3/8, ..., 9/8
68 * and 0 <= s <= 1/8 .
70 * 4. For x in [5/4, 107],
71 * erfc(x) = (1/x)*exp(-x*x-0.5625 + R(z))
72 * z=1/x^2
73 * The interval is partitioned into several segments
74 * of width 1/8 in 1/x.
76 * Note1:
77 * To compute exp(-x*x-0.5625+R/S), let s be a single
78 * precision number and s := x; then
79 * -x*x = -s*s + (s-x)*(s+x)
80 * exp(-x*x-0.5626+R/S) =
81 * exp(-s*s-0.5625)*exp((s-x)*(s+x)+R/S);
82 * Note2:
83 * Here 4 and 5 make use of the asymptotic series
84 * exp(-x*x)
85 * erfc(x) ~ ---------- * ( 1 + Poly(1/x^2) )
86 * x*sqrt(pi)
88 * 5. For inf > x >= 107
89 * erf(x) = sign(x) *(1 - tiny) (raise inexact)
90 * erfc(x) = tiny*tiny (raise underflow) if x > 0
91 * = 2 - tiny if x<0
93 * 7. Special case:
94 * erf(0) = 0, erf(inf) = 1, erf(-inf) = -1,
95 * erfc(0) = 1, erfc(inf) = 0, erfc(-inf) = 2,
96 * erfc/erf(NaN) is NaN
99 #include <errno.h>
100 #include <float.h>
101 #include <math.h>
102 #include <math_private.h>
103 #include <libm-alias-ldouble.h>
105 /* Evaluate P[n] x^n + P[n-1] x^(n-1) + ... + P[0] */
107 static _Float128
108 neval (_Float128 x, const _Float128 *p, int n)
110 _Float128 y;
112 p += n;
113 y = *p--;
116 y = y * x + *p--;
118 while (--n > 0);
119 return y;
123 /* Evaluate x^n+1 + P[n] x^(n) + P[n-1] x^(n-1) + ... + P[0] */
125 static _Float128
126 deval (_Float128 x, const _Float128 *p, int n)
128 _Float128 y;
130 p += n;
131 y = x + *p--;
134 y = y * x + *p--;
136 while (--n > 0);
137 return y;
142 static const _Float128
143 tiny = L(1e-4931),
144 one = 1,
145 two = 2,
146 /* 2/sqrt(pi) - 1 */
147 efx = L(1.2837916709551257389615890312154517168810E-1);
150 /* erf(x) = x + x R(x^2)
151 0 <= x <= 7/8
152 Peak relative error 1.8e-35 */
153 #define NTN1 8
154 static const _Float128 TN1[NTN1 + 1] =
156 L(-3.858252324254637124543172907442106422373E10),
157 L(9.580319248590464682316366876952214879858E10),
158 L(1.302170519734879977595901236693040544854E10),
159 L(2.922956950426397417800321486727032845006E9),
160 L(1.764317520783319397868923218385468729799E8),
161 L(1.573436014601118630105796794840834145120E7),
162 L(4.028077380105721388745632295157816229289E5),
163 L(1.644056806467289066852135096352853491530E4),
164 L(3.390868480059991640235675479463287886081E1)
166 #define NTD1 8
167 static const _Float128 TD1[NTD1 + 1] =
169 L(-3.005357030696532927149885530689529032152E11),
170 L(-1.342602283126282827411658673839982164042E11),
171 L(-2.777153893355340961288511024443668743399E10),
172 L(-3.483826391033531996955620074072768276974E9),
173 L(-2.906321047071299585682722511260895227921E8),
174 L(-1.653347985722154162439387878512427542691E7),
175 L(-6.245520581562848778466500301865173123136E5),
176 L(-1.402124304177498828590239373389110545142E4),
177 L(-1.209368072473510674493129989468348633579E2)
178 /* 1.0E0 */
182 /* erf(z+1) = erf_const + P(z)/Q(z)
183 -.125 <= z <= 0
184 Peak relative error 7.3e-36 */
185 static const _Float128 erf_const = L(0.845062911510467529296875);
186 #define NTN2 8
187 static const _Float128 TN2[NTN2 + 1] =
189 L(-4.088889697077485301010486931817357000235E1),
190 L(7.157046430681808553842307502826960051036E3),
191 L(-2.191561912574409865550015485451373731780E3),
192 L(2.180174916555316874988981177654057337219E3),
193 L(2.848578658049670668231333682379720943455E2),
194 L(1.630362490952512836762810462174798925274E2),
195 L(6.317712353961866974143739396865293596895E0),
196 L(2.450441034183492434655586496522857578066E1),
197 L(5.127662277706787664956025545897050896203E-1)
199 #define NTD2 8
200 static const _Float128 TD2[NTD2 + 1] =
202 L(1.731026445926834008273768924015161048885E4),
203 L(1.209682239007990370796112604286048173750E4),
204 L(1.160950290217993641320602282462976163857E4),
205 L(5.394294645127126577825507169061355698157E3),
206 L(2.791239340533632669442158497532521776093E3),
207 L(8.989365571337319032943005387378993827684E2),
208 L(2.974016493766349409725385710897298069677E2),
209 L(6.148192754590376378740261072533527271947E1),
210 L(1.178502892490738445655468927408440847480E1)
211 /* 1.0E0 */
215 /* erfc(x + 0.25) = erfc(0.25) + x R(x)
216 0 <= x < 0.125
217 Peak relative error 1.4e-35 */
218 #define NRNr13 8
219 static const _Float128 RNr13[NRNr13 + 1] =
221 L(-2.353707097641280550282633036456457014829E3),
222 L(3.871159656228743599994116143079870279866E2),
223 L(-3.888105134258266192210485617504098426679E2),
224 L(-2.129998539120061668038806696199343094971E1),
225 L(-8.125462263594034672468446317145384108734E1),
226 L(8.151549093983505810118308635926270319660E0),
227 L(-5.033362032729207310462422357772568553670E0),
228 L(-4.253956621135136090295893547735851168471E-2),
229 L(-8.098602878463854789780108161581050357814E-2)
231 #define NRDr13 7
232 static const _Float128 RDr13[NRDr13 + 1] =
234 L(2.220448796306693503549505450626652881752E3),
235 L(1.899133258779578688791041599040951431383E2),
236 L(1.061906712284961110196427571557149268454E3),
237 L(7.497086072306967965180978101974566760042E1),
238 L(2.146796115662672795876463568170441327274E2),
239 L(1.120156008362573736664338015952284925592E1),
240 L(2.211014952075052616409845051695042741074E1),
241 L(6.469655675326150785692908453094054988938E-1)
242 /* 1.0E0 */
244 /* erfc(0.25) = C13a + C13b to extra precision. */
245 static const _Float128 C13a = L(0.723663330078125);
246 static const _Float128 C13b = L(1.0279753638067014931732235184287934646022E-5);
249 /* erfc(x + 0.375) = erfc(0.375) + x R(x)
250 0 <= x < 0.125
251 Peak relative error 1.2e-35 */
252 #define NRNr14 8
253 static const _Float128 RNr14[NRNr14 + 1] =
255 L(-2.446164016404426277577283038988918202456E3),
256 L(6.718753324496563913392217011618096698140E2),
257 L(-4.581631138049836157425391886957389240794E2),
258 L(-2.382844088987092233033215402335026078208E1),
259 L(-7.119237852400600507927038680970936336458E1),
260 L(1.313609646108420136332418282286454287146E1),
261 L(-6.188608702082264389155862490056401365834E0),
262 L(-2.787116601106678287277373011101132659279E-2),
263 L(-2.230395570574153963203348263549700967918E-2)
265 #define NRDr14 7
266 static const _Float128 RDr14[NRDr14 + 1] =
268 L(2.495187439241869732696223349840963702875E3),
269 L(2.503549449872925580011284635695738412162E2),
270 L(1.159033560988895481698051531263861842461E3),
271 L(9.493751466542304491261487998684383688622E1),
272 L(2.276214929562354328261422263078480321204E2),
273 L(1.367697521219069280358984081407807931847E1),
274 L(2.276988395995528495055594829206582732682E1),
275 L(7.647745753648996559837591812375456641163E-1)
276 /* 1.0E0 */
278 /* erfc(0.375) = C14a + C14b to extra precision. */
279 static const _Float128 C14a = L(0.5958709716796875);
280 static const _Float128 C14b = L(1.2118885490201676174914080878232469565953E-5);
282 /* erfc(x + 0.5) = erfc(0.5) + x R(x)
283 0 <= x < 0.125
284 Peak relative error 4.7e-36 */
285 #define NRNr15 8
286 static const _Float128 RNr15[NRNr15 + 1] =
288 L(-2.624212418011181487924855581955853461925E3),
289 L(8.473828904647825181073831556439301342756E2),
290 L(-5.286207458628380765099405359607331669027E2),
291 L(-3.895781234155315729088407259045269652318E1),
292 L(-6.200857908065163618041240848728398496256E1),
293 L(1.469324610346924001393137895116129204737E1),
294 L(-6.961356525370658572800674953305625578903E0),
295 L(5.145724386641163809595512876629030548495E-3),
296 L(1.990253655948179713415957791776180406812E-2)
298 #define NRDr15 7
299 static const _Float128 RDr15[NRDr15 + 1] =
301 L(2.986190760847974943034021764693341524962E3),
302 L(5.288262758961073066335410218650047725985E2),
303 L(1.363649178071006978355113026427856008978E3),
304 L(1.921707975649915894241864988942255320833E2),
305 L(2.588651100651029023069013885900085533226E2),
306 L(2.628752920321455606558942309396855629459E1),
307 L(2.455649035885114308978333741080991380610E1),
308 L(1.378826653595128464383127836412100939126E0)
309 /* 1.0E0 */
311 /* erfc(0.5) = C15a + C15b to extra precision. */
312 static const _Float128 C15a = L(0.4794921875);
313 static const _Float128 C15b = L(7.9346869534623172533461080354712635484242E-6);
315 /* erfc(x + 0.625) = erfc(0.625) + x R(x)
316 0 <= x < 0.125
317 Peak relative error 5.1e-36 */
318 #define NRNr16 8
319 static const _Float128 RNr16[NRNr16 + 1] =
321 L(-2.347887943200680563784690094002722906820E3),
322 L(8.008590660692105004780722726421020136482E2),
323 L(-5.257363310384119728760181252132311447963E2),
324 L(-4.471737717857801230450290232600243795637E1),
325 L(-4.849540386452573306708795324759300320304E1),
326 L(1.140885264677134679275986782978655952843E1),
327 L(-6.731591085460269447926746876983786152300E0),
328 L(1.370831653033047440345050025876085121231E-1),
329 L(2.022958279982138755020825717073966576670E-2),
331 #define NRDr16 7
332 static const _Float128 RDr16[NRDr16 + 1] =
334 L(3.075166170024837215399323264868308087281E3),
335 L(8.730468942160798031608053127270430036627E2),
336 L(1.458472799166340479742581949088453244767E3),
337 L(3.230423687568019709453130785873540386217E2),
338 L(2.804009872719893612081109617983169474655E2),
339 L(4.465334221323222943418085830026979293091E1),
340 L(2.612723259683205928103787842214809134746E1),
341 L(2.341526751185244109722204018543276124997E0),
342 /* 1.0E0 */
344 /* erfc(0.625) = C16a + C16b to extra precision. */
345 static const _Float128 C16a = L(0.3767547607421875);
346 static const _Float128 C16b = L(4.3570693945275513594941232097252997287766E-6);
348 /* erfc(x + 0.75) = erfc(0.75) + x R(x)
349 0 <= x < 0.125
350 Peak relative error 1.7e-35 */
351 #define NRNr17 8
352 static const _Float128 RNr17[NRNr17 + 1] =
354 L(-1.767068734220277728233364375724380366826E3),
355 L(6.693746645665242832426891888805363898707E2),
356 L(-4.746224241837275958126060307406616817753E2),
357 L(-2.274160637728782675145666064841883803196E1),
358 L(-3.541232266140939050094370552538987982637E1),
359 L(6.988950514747052676394491563585179503865E0),
360 L(-5.807687216836540830881352383529281215100E0),
361 L(3.631915988567346438830283503729569443642E-1),
362 L(-1.488945487149634820537348176770282391202E-2)
364 #define NRDr17 7
365 static const _Float128 RDr17[NRDr17 + 1] =
367 L(2.748457523498150741964464942246913394647E3),
368 L(1.020213390713477686776037331757871252652E3),
369 L(1.388857635935432621972601695296561952738E3),
370 L(3.903363681143817750895999579637315491087E2),
371 L(2.784568344378139499217928969529219886578E2),
372 L(5.555800830216764702779238020065345401144E1),
373 L(2.646215470959050279430447295801291168941E1),
374 L(2.984905282103517497081766758550112011265E0),
375 /* 1.0E0 */
377 /* erfc(0.75) = C17a + C17b to extra precision. */
378 static const _Float128 C17a = L(0.2888336181640625);
379 static const _Float128 C17b = L(1.0748182422368401062165408589222625794046E-5);
382 /* erfc(x + 0.875) = erfc(0.875) + x R(x)
383 0 <= x < 0.125
384 Peak relative error 2.2e-35 */
385 #define NRNr18 8
386 static const _Float128 RNr18[NRNr18 + 1] =
388 L(-1.342044899087593397419622771847219619588E3),
389 L(6.127221294229172997509252330961641850598E2),
390 L(-4.519821356522291185621206350470820610727E2),
391 L(1.223275177825128732497510264197915160235E1),
392 L(-2.730789571382971355625020710543532867692E1),
393 L(4.045181204921538886880171727755445395862E0),
394 L(-4.925146477876592723401384464691452700539E0),
395 L(5.933878036611279244654299924101068088582E-1),
396 L(-5.557645435858916025452563379795159124753E-2)
398 #define NRDr18 7
399 static const _Float128 RDr18[NRDr18 + 1] =
401 L(2.557518000661700588758505116291983092951E3),
402 L(1.070171433382888994954602511991940418588E3),
403 L(1.344842834423493081054489613250688918709E3),
404 L(4.161144478449381901208660598266288188426E2),
405 L(2.763670252219855198052378138756906980422E2),
406 L(5.998153487868943708236273854747564557632E1),
407 L(2.657695108438628847733050476209037025318E1),
408 L(3.252140524394421868923289114410336976512E0),
409 /* 1.0E0 */
411 /* erfc(0.875) = C18a + C18b to extra precision. */
412 static const _Float128 C18a = L(0.215911865234375);
413 static const _Float128 C18b = L(1.3073705765341685464282101150637224028267E-5);
415 /* erfc(x + 1.0) = erfc(1.0) + x R(x)
416 0 <= x < 0.125
417 Peak relative error 1.6e-35 */
418 #define NRNr19 8
419 static const _Float128 RNr19[NRNr19 + 1] =
421 L(-1.139180936454157193495882956565663294826E3),
422 L(6.134903129086899737514712477207945973616E2),
423 L(-4.628909024715329562325555164720732868263E2),
424 L(4.165702387210732352564932347500364010833E1),
425 L(-2.286979913515229747204101330405771801610E1),
426 L(1.870695256449872743066783202326943667722E0),
427 L(-4.177486601273105752879868187237000032364E0),
428 L(7.533980372789646140112424811291782526263E-1),
429 L(-8.629945436917752003058064731308767664446E-2)
431 #define NRDr19 7
432 static const _Float128 RDr19[NRDr19 + 1] =
434 L(2.744303447981132701432716278363418643778E3),
435 L(1.266396359526187065222528050591302171471E3),
436 L(1.466739461422073351497972255511919814273E3),
437 L(4.868710570759693955597496520298058147162E2),
438 L(2.993694301559756046478189634131722579643E2),
439 L(6.868976819510254139741559102693828237440E1),
440 L(2.801505816247677193480190483913753613630E1),
441 L(3.604439909194350263552750347742663954481E0),
442 /* 1.0E0 */
444 /* erfc(1.0) = C19a + C19b to extra precision. */
445 static const _Float128 C19a = L(0.15728759765625);
446 static const _Float128 C19b = L(1.1609394035130658779364917390740703933002E-5);
448 /* erfc(x + 1.125) = erfc(1.125) + x R(x)
449 0 <= x < 0.125
450 Peak relative error 3.6e-36 */
451 #define NRNr20 8
452 static const _Float128 RNr20[NRNr20 + 1] =
454 L(-9.652706916457973956366721379612508047640E2),
455 L(5.577066396050932776683469951773643880634E2),
456 L(-4.406335508848496713572223098693575485978E2),
457 L(5.202893466490242733570232680736966655434E1),
458 L(-1.931311847665757913322495948705563937159E1),
459 L(-9.364318268748287664267341457164918090611E-2),
460 L(-3.306390351286352764891355375882586201069E0),
461 L(7.573806045289044647727613003096916516475E-1),
462 L(-9.611744011489092894027478899545635991213E-2)
464 #define NRDr20 7
465 static const _Float128 RDr20[NRDr20 + 1] =
467 L(3.032829629520142564106649167182428189014E3),
468 L(1.659648470721967719961167083684972196891E3),
469 L(1.703545128657284619402511356932569292535E3),
470 L(6.393465677731598872500200253155257708763E2),
471 L(3.489131397281030947405287112726059221934E2),
472 L(8.848641738570783406484348434387611713070E1),
473 L(3.132269062552392974833215844236160958502E1),
474 L(4.430131663290563523933419966185230513168E0)
475 /* 1.0E0 */
477 /* erfc(1.125) = C20a + C20b to extra precision. */
478 static const _Float128 C20a = L(0.111602783203125);
479 static const _Float128 C20b = L(8.9850951672359304215530728365232161564636E-6);
481 /* erfc(1/x) = 1/x exp (-1/x^2 - 0.5625 + R(1/x^2))
482 7/8 <= 1/x < 1
483 Peak relative error 1.4e-35 */
484 #define NRNr8 9
485 static const _Float128 RNr8[NRNr8 + 1] =
487 L(3.587451489255356250759834295199296936784E1),
488 L(5.406249749087340431871378009874875889602E2),
489 L(2.931301290625250886238822286506381194157E3),
490 L(7.359254185241795584113047248898753470923E3),
491 L(9.201031849810636104112101947312492532314E3),
492 L(5.749697096193191467751650366613289284777E3),
493 L(1.710415234419860825710780802678697889231E3),
494 L(2.150753982543378580859546706243022719599E2),
495 L(8.740953582272147335100537849981160931197E0),
496 L(4.876422978828717219629814794707963640913E-2)
498 #define NRDr8 8
499 static const _Float128 RDr8[NRDr8 + 1] =
501 L(6.358593134096908350929496535931630140282E1),
502 L(9.900253816552450073757174323424051765523E2),
503 L(5.642928777856801020545245437089490805186E3),
504 L(1.524195375199570868195152698617273739609E4),
505 L(2.113829644500006749947332935305800887345E4),
506 L(1.526438562626465706267943737310282977138E4),
507 L(5.561370922149241457131421914140039411782E3),
508 L(9.394035530179705051609070428036834496942E2),
509 L(6.147019596150394577984175188032707343615E1)
510 /* 1.0E0 */
513 /* erfc(1/x) = 1/x exp (-1/x^2 - 0.5625 + R(1/x^2))
514 0.75 <= 1/x <= 0.875
515 Peak relative error 2.0e-36 */
516 #define NRNr7 9
517 static const _Float128 RNr7[NRNr7 + 1] =
519 L(1.686222193385987690785945787708644476545E1),
520 L(1.178224543567604215602418571310612066594E3),
521 L(1.764550584290149466653899886088166091093E4),
522 L(1.073758321890334822002849369898232811561E5),
523 L(3.132840749205943137619839114451290324371E5),
524 L(4.607864939974100224615527007793867585915E5),
525 L(3.389781820105852303125270837910972384510E5),
526 L(1.174042187110565202875011358512564753399E5),
527 L(1.660013606011167144046604892622504338313E4),
528 L(6.700393957480661937695573729183733234400E2)
530 #define NRDr7 9
531 static const _Float128 RDr7[NRDr7 + 1] =
533 L(-1.709305024718358874701575813642933561169E3),
534 L(-3.280033887481333199580464617020514788369E4),
535 L(-2.345284228022521885093072363418750835214E5),
536 L(-8.086758123097763971926711729242327554917E5),
537 L(-1.456900414510108718402423999575992450138E6),
538 L(-1.391654264881255068392389037292702041855E6),
539 L(-6.842360801869939983674527468509852583855E5),
540 L(-1.597430214446573566179675395199807533371E5),
541 L(-1.488876130609876681421645314851760773480E4),
542 L(-3.511762950935060301403599443436465645703E2)
543 /* 1.0E0 */
546 /* erfc(1/x) = 1/x exp(-1/x^2 - 0.5625 + R(1/x^2))
547 5/8 <= 1/x < 3/4
548 Peak relative error 1.9e-35 */
549 #define NRNr6 9
550 static const _Float128 RNr6[NRNr6 + 1] =
552 L(1.642076876176834390623842732352935761108E0),
553 L(1.207150003611117689000664385596211076662E2),
554 L(2.119260779316389904742873816462800103939E3),
555 L(1.562942227734663441801452930916044224174E4),
556 L(5.656779189549710079988084081145693580479E4),
557 L(1.052166241021481691922831746350942786299E5),
558 L(9.949798524786000595621602790068349165758E4),
559 L(4.491790734080265043407035220188849562856E4),
560 L(8.377074098301530326270432059434791287601E3),
561 L(4.506934806567986810091824791963991057083E2)
563 #define NRDr6 9
564 static const _Float128 RDr6[NRDr6 + 1] =
566 L(-1.664557643928263091879301304019826629067E2),
567 L(-3.800035902507656624590531122291160668452E3),
568 L(-3.277028191591734928360050685359277076056E4),
569 L(-1.381359471502885446400589109566587443987E5),
570 L(-3.082204287382581873532528989283748656546E5),
571 L(-3.691071488256738343008271448234631037095E5),
572 L(-2.300482443038349815750714219117566715043E5),
573 L(-6.873955300927636236692803579555752171530E4),
574 L(-8.262158817978334142081581542749986845399E3),
575 L(-2.517122254384430859629423488157361983661E2)
576 /* 1.00 */
579 /* erfc(1/x) = 1/x exp(-1/x^2 - 0.5625 + R(1/x^2))
580 1/2 <= 1/x < 5/8
581 Peak relative error 4.6e-36 */
582 #define NRNr5 10
583 static const _Float128 RNr5[NRNr5 + 1] =
585 L(-3.332258927455285458355550878136506961608E-3),
586 L(-2.697100758900280402659586595884478660721E-1),
587 L(-6.083328551139621521416618424949137195536E0),
588 L(-6.119863528983308012970821226810162441263E1),
589 L(-3.176535282475593173248810678636522589861E2),
590 L(-8.933395175080560925809992467187963260693E2),
591 L(-1.360019508488475978060917477620199499560E3),
592 L(-1.075075579828188621541398761300910213280E3),
593 L(-4.017346561586014822824459436695197089916E2),
594 L(-5.857581368145266249509589726077645791341E1),
595 L(-2.077715925587834606379119585995758954399E0)
597 #define NRDr5 9
598 static const _Float128 RDr5[NRDr5 + 1] =
600 L(3.377879570417399341550710467744693125385E-1),
601 L(1.021963322742390735430008860602594456187E1),
602 L(1.200847646592942095192766255154827011939E2),
603 L(7.118915528142927104078182863387116942836E2),
604 L(2.318159380062066469386544552429625026238E3),
605 L(4.238729853534009221025582008928765281620E3),
606 L(4.279114907284825886266493994833515580782E3),
607 L(2.257277186663261531053293222591851737504E3),
608 L(5.570475501285054293371908382916063822957E2),
609 L(5.142189243856288981145786492585432443560E1)
610 /* 1.0E0 */
613 /* erfc(1/x) = 1/x exp(-1/x^2 - 0.5625 + R(1/x^2))
614 3/8 <= 1/x < 1/2
615 Peak relative error 2.0e-36 */
616 #define NRNr4 10
617 static const _Float128 RNr4[NRNr4 + 1] =
619 L(3.258530712024527835089319075288494524465E-3),
620 L(2.987056016877277929720231688689431056567E-1),
621 L(8.738729089340199750734409156830371528862E0),
622 L(1.207211160148647782396337792426311125923E2),
623 L(8.997558632489032902250523945248208224445E2),
624 L(3.798025197699757225978410230530640879762E3),
625 L(9.113203668683080975637043118209210146846E3),
626 L(1.203285891339933238608683715194034900149E4),
627 L(8.100647057919140328536743641735339740855E3),
628 L(2.383888249907144945837976899822927411769E3),
629 L(2.127493573166454249221983582495245662319E2)
631 #define NRDr4 10
632 static const _Float128 RDr4[NRDr4 + 1] =
634 L(-3.303141981514540274165450687270180479586E-1),
635 L(-1.353768629363605300707949368917687066724E1),
636 L(-2.206127630303621521950193783894598987033E2),
637 L(-1.861800338758066696514480386180875607204E3),
638 L(-8.889048775872605708249140016201753255599E3),
639 L(-2.465888106627948210478692168261494857089E4),
640 L(-3.934642211710774494879042116768390014289E4),
641 L(-3.455077258242252974937480623730228841003E4),
642 L(-1.524083977439690284820586063729912653196E4),
643 L(-2.810541887397984804237552337349093953857E3),
644 L(-1.343929553541159933824901621702567066156E2)
645 /* 1.0E0 */
648 /* erfc(1/x) = 1/x exp(-1/x^2 - 0.5625 + R(1/x^2))
649 1/4 <= 1/x < 3/8
650 Peak relative error 8.4e-37 */
651 #define NRNr3 11
652 static const _Float128 RNr3[NRNr3 + 1] =
654 L(-1.952401126551202208698629992497306292987E-6),
655 L(-2.130881743066372952515162564941682716125E-4),
656 L(-8.376493958090190943737529486107282224387E-3),
657 L(-1.650592646560987700661598877522831234791E-1),
658 L(-1.839290818933317338111364667708678163199E0),
659 L(-1.216278715570882422410442318517814388470E1),
660 L(-4.818759344462360427612133632533779091386E1),
661 L(-1.120994661297476876804405329172164436784E2),
662 L(-1.452850765662319264191141091859300126931E2),
663 L(-9.485207851128957108648038238656777241333E1),
664 L(-2.563663855025796641216191848818620020073E1),
665 L(-1.787995944187565676837847610706317833247E0)
667 #define NRDr3 10
668 static const _Float128 RDr3[NRDr3 + 1] =
670 L(1.979130686770349481460559711878399476903E-4),
671 L(1.156941716128488266238105813374635099057E-2),
672 L(2.752657634309886336431266395637285974292E-1),
673 L(3.482245457248318787349778336603569327521E0),
674 L(2.569347069372696358578399521203959253162E1),
675 L(1.142279000180457419740314694631879921561E2),
676 L(3.056503977190564294341422623108332700840E2),
677 L(4.780844020923794821656358157128719184422E2),
678 L(4.105972727212554277496256802312730410518E2),
679 L(1.724072188063746970865027817017067646246E2),
680 L(2.815939183464818198705278118326590370435E1)
681 /* 1.0E0 */
684 /* erfc(1/x) = 1/x exp(-1/x^2 - 0.5625 + R(1/x^2))
685 1/8 <= 1/x < 1/4
686 Peak relative error 1.5e-36 */
687 #define NRNr2 11
688 static const _Float128 RNr2[NRNr2 + 1] =
690 L(-2.638914383420287212401687401284326363787E-8),
691 L(-3.479198370260633977258201271399116766619E-6),
692 L(-1.783985295335697686382487087502222519983E-4),
693 L(-4.777876933122576014266349277217559356276E-3),
694 L(-7.450634738987325004070761301045014986520E-2),
695 L(-7.068318854874733315971973707247467326619E-1),
696 L(-4.113919921935944795764071670806867038732E0),
697 L(-1.440447573226906222417767283691888875082E1),
698 L(-2.883484031530718428417168042141288943905E1),
699 L(-2.990886974328476387277797361464279931446E1),
700 L(-1.325283914915104866248279787536128997331E1),
701 L(-1.572436106228070195510230310658206154374E0)
703 #define NRDr2 10
704 static const _Float128 RDr2[NRDr2 + 1] =
706 L(2.675042728136731923554119302571867799673E-6),
707 L(2.170997868451812708585443282998329996268E-4),
708 L(7.249969752687540289422684951196241427445E-3),
709 L(1.302040375859768674620410563307838448508E-1),
710 L(1.380202483082910888897654537144485285549E0),
711 L(8.926594113174165352623847870299170069350E0),
712 L(3.521089584782616472372909095331572607185E1),
713 L(8.233547427533181375185259050330809105570E1),
714 L(1.072971579885803033079469639073292840135E2),
715 L(6.943803113337964469736022094105143158033E1),
716 L(1.775695341031607738233608307835017282662E1)
717 /* 1.0E0 */
720 /* erfc(1/x) = 1/x exp(-1/x^2 - 0.5625 + R(1/x^2))
721 1/128 <= 1/x < 1/8
722 Peak relative error 2.2e-36 */
723 #define NRNr1 9
724 static const _Float128 RNr1[NRNr1 + 1] =
726 L(-4.250780883202361946697751475473042685782E-8),
727 L(-5.375777053288612282487696975623206383019E-6),
728 L(-2.573645949220896816208565944117382460452E-4),
729 L(-6.199032928113542080263152610799113086319E-3),
730 L(-8.262721198693404060380104048479916247786E-2),
731 L(-6.242615227257324746371284637695778043982E-1),
732 L(-2.609874739199595400225113299437099626386E0),
733 L(-5.581967563336676737146358534602770006970E0),
734 L(-5.124398923356022609707490956634280573882E0),
735 L(-1.290865243944292370661544030414667556649E0)
737 #define NRDr1 8
738 static const _Float128 RDr1[NRDr1 + 1] =
740 L(4.308976661749509034845251315983612976224E-6),
741 L(3.265390126432780184125233455960049294580E-4),
742 L(9.811328839187040701901866531796570418691E-3),
743 L(1.511222515036021033410078631914783519649E-1),
744 L(1.289264341917429958858379585970225092274E0),
745 L(6.147640356182230769548007536914983522270E0),
746 L(1.573966871337739784518246317003956180750E1),
747 L(1.955534123435095067199574045529218238263E1),
748 L(9.472613121363135472247929109615785855865E0)
749 /* 1.0E0 */
753 _Float128
754 __erfl (_Float128 x)
756 _Float128 a, y, z;
757 int32_t i, ix, sign;
758 ieee854_long_double_shape_type u;
760 u.value = x;
761 sign = u.parts32.w0;
762 ix = sign & 0x7fffffff;
764 if (ix >= 0x7fff0000)
765 { /* erf(nan)=nan */
766 i = ((sign & 0xffff0000) >> 31) << 1;
767 return (_Float128) (1 - i) + one / x; /* erf(+-inf)=+-1 */
770 if (ix >= 0x3fff0000) /* |x| >= 1.0 */
772 if (ix >= 0x40030000 && sign > 0)
773 return one; /* x >= 16, avoid spurious underflow from erfc. */
774 y = __erfcl (x);
775 return (one - y);
776 /* return (one - __erfcl (x)); */
778 u.parts32.w0 = ix;
779 a = u.value;
780 z = x * x;
781 if (ix < 0x3ffec000) /* a < 0.875 */
783 if (ix < 0x3fc60000) /* |x|<2**-57 */
785 if (ix < 0x00080000)
787 /* Avoid spurious underflow. */
788 _Float128 ret = 0.0625 * (16.0 * x + (16.0 * efx) * x);
789 math_check_force_underflow (ret);
790 return ret;
792 return x + efx * x;
794 y = a + a * neval (z, TN1, NTN1) / deval (z, TD1, NTD1);
796 else
798 a = a - one;
799 y = erf_const + neval (a, TN2, NTN2) / deval (a, TD2, NTD2);
802 if (sign & 0x80000000) /* x < 0 */
803 y = -y;
804 return( y );
807 libm_alias_ldouble (__erf, erf)
808 _Float128
809 __erfcl (_Float128 x)
811 _Float128 y, z, p, r;
812 int32_t i, ix, sign;
813 ieee854_long_double_shape_type u;
815 u.value = x;
816 sign = u.parts32.w0;
817 ix = sign & 0x7fffffff;
818 u.parts32.w0 = ix;
820 if (ix >= 0x7fff0000)
821 { /* erfc(nan)=nan */
822 /* erfc(+-inf)=0,2 */
823 return (_Float128) (((uint32_t) sign >> 31) << 1) + one / x;
826 if (ix < 0x3ffd0000) /* |x| <1/4 */
828 if (ix < 0x3f8d0000) /* |x|<2**-114 */
829 return one - x;
830 return one - __erfl (x);
832 if (ix < 0x3fff4000) /* 1.25 */
834 x = u.value;
835 i = 8.0 * x;
836 switch (i)
838 case 2:
839 z = x - L(0.25);
840 y = C13b + z * neval (z, RNr13, NRNr13) / deval (z, RDr13, NRDr13);
841 y += C13a;
842 break;
843 case 3:
844 z = x - L(0.375);
845 y = C14b + z * neval (z, RNr14, NRNr14) / deval (z, RDr14, NRDr14);
846 y += C14a;
847 break;
848 case 4:
849 z = x - L(0.5);
850 y = C15b + z * neval (z, RNr15, NRNr15) / deval (z, RDr15, NRDr15);
851 y += C15a;
852 break;
853 case 5:
854 z = x - L(0.625);
855 y = C16b + z * neval (z, RNr16, NRNr16) / deval (z, RDr16, NRDr16);
856 y += C16a;
857 break;
858 case 6:
859 z = x - L(0.75);
860 y = C17b + z * neval (z, RNr17, NRNr17) / deval (z, RDr17, NRDr17);
861 y += C17a;
862 break;
863 case 7:
864 z = x - L(0.875);
865 y = C18b + z * neval (z, RNr18, NRNr18) / deval (z, RDr18, NRDr18);
866 y += C18a;
867 break;
868 case 8:
869 z = x - 1;
870 y = C19b + z * neval (z, RNr19, NRNr19) / deval (z, RDr19, NRDr19);
871 y += C19a;
872 break;
873 default: /* i == 9. */
874 z = x - L(1.125);
875 y = C20b + z * neval (z, RNr20, NRNr20) / deval (z, RDr20, NRDr20);
876 y += C20a;
877 break;
879 if (sign & 0x80000000)
880 y = 2 - y;
881 return y;
883 /* 1.25 < |x| < 107 */
884 if (ix < 0x4005ac00)
886 /* x < -9 */
887 if ((ix >= 0x40022000) && (sign & 0x80000000))
888 return two - tiny;
890 x = fabsl (x);
891 z = one / (x * x);
892 i = 8.0 / x;
893 switch (i)
895 default:
896 case 0:
897 p = neval (z, RNr1, NRNr1) / deval (z, RDr1, NRDr1);
898 break;
899 case 1:
900 p = neval (z, RNr2, NRNr2) / deval (z, RDr2, NRDr2);
901 break;
902 case 2:
903 p = neval (z, RNr3, NRNr3) / deval (z, RDr3, NRDr3);
904 break;
905 case 3:
906 p = neval (z, RNr4, NRNr4) / deval (z, RDr4, NRDr4);
907 break;
908 case 4:
909 p = neval (z, RNr5, NRNr5) / deval (z, RDr5, NRDr5);
910 break;
911 case 5:
912 p = neval (z, RNr6, NRNr6) / deval (z, RDr6, NRDr6);
913 break;
914 case 6:
915 p = neval (z, RNr7, NRNr7) / deval (z, RDr7, NRDr7);
916 break;
917 case 7:
918 p = neval (z, RNr8, NRNr8) / deval (z, RDr8, NRDr8);
919 break;
921 u.value = x;
922 u.parts32.w3 = 0;
923 u.parts32.w2 &= 0xfe000000;
924 z = u.value;
925 r = __ieee754_expl (-z * z - 0.5625) *
926 __ieee754_expl ((z - x) * (z + x) + p);
927 if ((sign & 0x80000000) == 0)
929 _Float128 ret = r / x;
930 if (ret == 0)
931 __set_errno (ERANGE);
932 return ret;
934 else
935 return two - r / x;
937 else
939 if ((sign & 0x80000000) == 0)
941 __set_errno (ERANGE);
942 return tiny * tiny;
944 else
945 return two - tiny;
949 libm_alias_ldouble (__erfc, erfc)