erf.hpp 56 KB

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  1. // (C) Copyright John Maddock 2006.
  2. // Use, modification and distribution are subject to the
  3. // Boost Software License, Version 1.0. (See accompanying file
  4. // LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
  5. #ifndef BOOST_MATH_SPECIAL_ERF_HPP
  6. #define BOOST_MATH_SPECIAL_ERF_HPP
  7. #ifdef _MSC_VER
  8. #pragma once
  9. #endif
  10. #include <boost/math/special_functions/math_fwd.hpp>
  11. #include <boost/math/tools/config.hpp>
  12. #include <boost/math/special_functions/gamma.hpp>
  13. #include <boost/math/tools/roots.hpp>
  14. #include <boost/math/policies/error_handling.hpp>
  15. #include <boost/math/tools/big_constant.hpp>
  16. #if defined(__GNUC__) && defined(BOOST_MATH_USE_FLOAT128)
  17. //
  18. // This is the only way we can avoid
  19. // warning: non-standard suffix on floating constant [-Wpedantic]
  20. // when building with -Wall -pedantic. Neither __extension__
  21. // nor #pragma dianostic ignored work :(
  22. //
  23. #pragma GCC system_header
  24. #endif
  25. namespace boost{ namespace math{
  26. namespace detail
  27. {
  28. //
  29. // Asymptotic series for large z:
  30. //
  31. template <class T>
  32. struct erf_asympt_series_t
  33. {
  34. erf_asympt_series_t(T z) : xx(2 * -z * z), tk(1)
  35. {
  36. BOOST_MATH_STD_USING
  37. result = -exp(-z * z) / sqrt(boost::math::constants::pi<T>());
  38. result /= z;
  39. }
  40. typedef T result_type;
  41. T operator()()
  42. {
  43. BOOST_MATH_STD_USING
  44. T r = result;
  45. result *= tk / xx;
  46. tk += 2;
  47. if( fabs(r) < fabs(result))
  48. result = 0;
  49. return r;
  50. }
  51. private:
  52. T result;
  53. T xx;
  54. int tk;
  55. };
  56. //
  57. // How large z has to be in order to ensure that the series converges:
  58. //
  59. template <class T>
  60. inline float erf_asymptotic_limit_N(const T&)
  61. {
  62. return (std::numeric_limits<float>::max)();
  63. }
  64. inline float erf_asymptotic_limit_N(const mpl::int_<24>&)
  65. {
  66. return 2.8F;
  67. }
  68. inline float erf_asymptotic_limit_N(const mpl::int_<53>&)
  69. {
  70. return 4.3F;
  71. }
  72. inline float erf_asymptotic_limit_N(const mpl::int_<64>&)
  73. {
  74. return 4.8F;
  75. }
  76. inline float erf_asymptotic_limit_N(const mpl::int_<106>&)
  77. {
  78. return 6.5F;
  79. }
  80. inline float erf_asymptotic_limit_N(const mpl::int_<113>&)
  81. {
  82. return 6.8F;
  83. }
  84. template <class T, class Policy>
  85. inline T erf_asymptotic_limit()
  86. {
  87. typedef typename policies::precision<T, Policy>::type precision_type;
  88. typedef typename mpl::if_<
  89. mpl::less_equal<precision_type, mpl::int_<24> >,
  90. typename mpl::if_<
  91. mpl::less_equal<precision_type, mpl::int_<0> >,
  92. mpl::int_<0>,
  93. mpl::int_<24>
  94. >::type,
  95. typename mpl::if_<
  96. mpl::less_equal<precision_type, mpl::int_<53> >,
  97. mpl::int_<53>,
  98. typename mpl::if_<
  99. mpl::less_equal<precision_type, mpl::int_<64> >,
  100. mpl::int_<64>,
  101. typename mpl::if_<
  102. mpl::less_equal<precision_type, mpl::int_<106> >,
  103. mpl::int_<106>,
  104. typename mpl::if_<
  105. mpl::less_equal<precision_type, mpl::int_<113> >,
  106. mpl::int_<113>,
  107. mpl::int_<0>
  108. >::type
  109. >::type
  110. >::type
  111. >::type
  112. >::type tag_type;
  113. return erf_asymptotic_limit_N(tag_type());
  114. }
  115. template <class T, class Policy, class Tag>
  116. T erf_imp(T z, bool invert, const Policy& pol, const Tag& t)
  117. {
  118. BOOST_MATH_STD_USING
  119. BOOST_MATH_INSTRUMENT_CODE("Generic erf_imp called");
  120. if(z < 0)
  121. {
  122. if(!invert)
  123. return -erf_imp(T(-z), invert, pol, t);
  124. else
  125. return 1 + erf_imp(T(-z), false, pol, t);
  126. }
  127. T result;
  128. if(!invert && (z > detail::erf_asymptotic_limit<T, Policy>()))
  129. {
  130. detail::erf_asympt_series_t<T> s(z);
  131. boost::uintmax_t max_iter = policies::get_max_series_iterations<Policy>();
  132. result = boost::math::tools::sum_series(s, policies::get_epsilon<T, Policy>(), max_iter, 1);
  133. policies::check_series_iterations<T>("boost::math::erf<%1%>(%1%, %1%)", max_iter, pol);
  134. }
  135. else
  136. {
  137. T x = z * z;
  138. if(x < 0.6)
  139. {
  140. // Compute P:
  141. result = z * exp(-x);
  142. result /= sqrt(boost::math::constants::pi<T>());
  143. if(result != 0)
  144. result *= 2 * detail::lower_gamma_series(T(0.5f), x, pol);
  145. }
  146. else if(x < 1.1f)
  147. {
  148. // Compute Q:
  149. invert = !invert;
  150. result = tgamma_small_upper_part(T(0.5f), x, pol);
  151. result /= sqrt(boost::math::constants::pi<T>());
  152. }
  153. else if(x > 1 / tools::epsilon<T>())
  154. {
  155. // http://functions.wolfram.com/06.27.06.0006.02
  156. invert = !invert;
  157. result = exp(-x) / (constants::root_pi<T>() * z);
  158. }
  159. else
  160. {
  161. // Compute Q:
  162. invert = !invert;
  163. result = z * exp(-x);
  164. result /= boost::math::constants::root_pi<T>();
  165. result *= upper_gamma_fraction(T(0.5f), x, policies::get_epsilon<T, Policy>());
  166. }
  167. }
  168. if(invert)
  169. result = 1 - result;
  170. return result;
  171. }
  172. template <class T, class Policy>
  173. T erf_imp(T z, bool invert, const Policy& pol, const mpl::int_<53>& t)
  174. {
  175. BOOST_MATH_STD_USING
  176. BOOST_MATH_INSTRUMENT_CODE("53-bit precision erf_imp called");
  177. if ((boost::math::isnan)(z))
  178. return policies::raise_denorm_error("boost::math::erf<%1%>(%1%)", "Expected a finite argument but got %1%", z, pol);
  179. if(z < 0)
  180. {
  181. if(!invert)
  182. return -erf_imp(T(-z), invert, pol, t);
  183. else if(z < -0.5)
  184. return 2 - erf_imp(T(-z), invert, pol, t);
  185. else
  186. return 1 + erf_imp(T(-z), false, pol, t);
  187. }
  188. T result;
  189. //
  190. // Big bunch of selection statements now to pick
  191. // which implementation to use,
  192. // try to put most likely options first:
  193. //
  194. if(z < 0.5)
  195. {
  196. //
  197. // We're going to calculate erf:
  198. //
  199. if(z < 1e-10)
  200. {
  201. if(z == 0)
  202. {
  203. result = T(0);
  204. }
  205. else
  206. {
  207. static const T c = BOOST_MATH_BIG_CONSTANT(T, 53, 0.003379167095512573896158903121545171688);
  208. result = static_cast<T>(z * 1.125f + z * c);
  209. }
  210. }
  211. else
  212. {
  213. // Maximum Deviation Found: 1.561e-17
  214. // Expected Error Term: 1.561e-17
  215. // Maximum Relative Change in Control Points: 1.155e-04
  216. // Max Error found at double precision = 2.961182e-17
  217. static const T Y = 1.044948577880859375f;
  218. static const T P[] = {
  219. BOOST_MATH_BIG_CONSTANT(T, 53, 0.0834305892146531832907),
  220. BOOST_MATH_BIG_CONSTANT(T, 53, -0.338165134459360935041),
  221. BOOST_MATH_BIG_CONSTANT(T, 53, -0.0509990735146777432841),
  222. BOOST_MATH_BIG_CONSTANT(T, 53, -0.00772758345802133288487),
  223. BOOST_MATH_BIG_CONSTANT(T, 53, -0.000322780120964605683831),
  224. };
  225. static const T Q[] = {
  226. BOOST_MATH_BIG_CONSTANT(T, 53, 1.0),
  227. BOOST_MATH_BIG_CONSTANT(T, 53, 0.455004033050794024546),
  228. BOOST_MATH_BIG_CONSTANT(T, 53, 0.0875222600142252549554),
  229. BOOST_MATH_BIG_CONSTANT(T, 53, 0.00858571925074406212772),
  230. BOOST_MATH_BIG_CONSTANT(T, 53, 0.000370900071787748000569),
  231. };
  232. T zz = z * z;
  233. result = z * (Y + tools::evaluate_polynomial(P, zz) / tools::evaluate_polynomial(Q, zz));
  234. }
  235. }
  236. else if(invert ? (z < 28) : (z < 5.8f))
  237. {
  238. //
  239. // We'll be calculating erfc:
  240. //
  241. invert = !invert;
  242. if(z < 1.5f)
  243. {
  244. // Maximum Deviation Found: 3.702e-17
  245. // Expected Error Term: 3.702e-17
  246. // Maximum Relative Change in Control Points: 2.845e-04
  247. // Max Error found at double precision = 4.841816e-17
  248. static const T Y = 0.405935764312744140625f;
  249. static const T P[] = {
  250. BOOST_MATH_BIG_CONSTANT(T, 53, -0.098090592216281240205),
  251. BOOST_MATH_BIG_CONSTANT(T, 53, 0.178114665841120341155),
  252. BOOST_MATH_BIG_CONSTANT(T, 53, 0.191003695796775433986),
  253. BOOST_MATH_BIG_CONSTANT(T, 53, 0.0888900368967884466578),
  254. BOOST_MATH_BIG_CONSTANT(T, 53, 0.0195049001251218801359),
  255. BOOST_MATH_BIG_CONSTANT(T, 53, 0.00180424538297014223957),
  256. };
  257. static const T Q[] = {
  258. BOOST_MATH_BIG_CONSTANT(T, 53, 1.0),
  259. BOOST_MATH_BIG_CONSTANT(T, 53, 1.84759070983002217845),
  260. BOOST_MATH_BIG_CONSTANT(T, 53, 1.42628004845511324508),
  261. BOOST_MATH_BIG_CONSTANT(T, 53, 0.578052804889902404909),
  262. BOOST_MATH_BIG_CONSTANT(T, 53, 0.12385097467900864233),
  263. BOOST_MATH_BIG_CONSTANT(T, 53, 0.0113385233577001411017),
  264. BOOST_MATH_BIG_CONSTANT(T, 53, 0.337511472483094676155e-5),
  265. };
  266. BOOST_MATH_INSTRUMENT_VARIABLE(Y);
  267. BOOST_MATH_INSTRUMENT_VARIABLE(P[0]);
  268. BOOST_MATH_INSTRUMENT_VARIABLE(Q[0]);
  269. BOOST_MATH_INSTRUMENT_VARIABLE(z);
  270. result = Y + tools::evaluate_polynomial(P, T(z - 0.5)) / tools::evaluate_polynomial(Q, T(z - 0.5));
  271. BOOST_MATH_INSTRUMENT_VARIABLE(result);
  272. result *= exp(-z * z) / z;
  273. BOOST_MATH_INSTRUMENT_VARIABLE(result);
  274. }
  275. else if(z < 2.5f)
  276. {
  277. // Max Error found at double precision = 6.599585e-18
  278. // Maximum Deviation Found: 3.909e-18
  279. // Expected Error Term: 3.909e-18
  280. // Maximum Relative Change in Control Points: 9.886e-05
  281. static const T Y = 0.50672817230224609375f;
  282. static const T P[] = {
  283. BOOST_MATH_BIG_CONSTANT(T, 53, -0.0243500476207698441272),
  284. BOOST_MATH_BIG_CONSTANT(T, 53, 0.0386540375035707201728),
  285. BOOST_MATH_BIG_CONSTANT(T, 53, 0.04394818964209516296),
  286. BOOST_MATH_BIG_CONSTANT(T, 53, 0.0175679436311802092299),
  287. BOOST_MATH_BIG_CONSTANT(T, 53, 0.00323962406290842133584),
  288. BOOST_MATH_BIG_CONSTANT(T, 53, 0.000235839115596880717416),
  289. };
  290. static const T Q[] = {
  291. BOOST_MATH_BIG_CONSTANT(T, 53, 1.0),
  292. BOOST_MATH_BIG_CONSTANT(T, 53, 1.53991494948552447182),
  293. BOOST_MATH_BIG_CONSTANT(T, 53, 0.982403709157920235114),
  294. BOOST_MATH_BIG_CONSTANT(T, 53, 0.325732924782444448493),
  295. BOOST_MATH_BIG_CONSTANT(T, 53, 0.0563921837420478160373),
  296. BOOST_MATH_BIG_CONSTANT(T, 53, 0.00410369723978904575884),
  297. };
  298. result = Y + tools::evaluate_polynomial(P, T(z - 1.5)) / tools::evaluate_polynomial(Q, T(z - 1.5));
  299. T hi, lo;
  300. int expon;
  301. hi = floor(ldexp(frexp(z, &expon), 26));
  302. hi = ldexp(hi, expon - 26);
  303. lo = z - hi;
  304. T sq = z * z;
  305. T err_sqr = ((hi * hi - sq) + 2 * hi * lo) + lo * lo;
  306. result *= exp(-sq) * exp(-err_sqr) / z;
  307. }
  308. else if(z < 4.5f)
  309. {
  310. // Maximum Deviation Found: 1.512e-17
  311. // Expected Error Term: 1.512e-17
  312. // Maximum Relative Change in Control Points: 2.222e-04
  313. // Max Error found at double precision = 2.062515e-17
  314. static const T Y = 0.5405750274658203125f;
  315. static const T P[] = {
  316. BOOST_MATH_BIG_CONSTANT(T, 53, 0.00295276716530971662634),
  317. BOOST_MATH_BIG_CONSTANT(T, 53, 0.0137384425896355332126),
  318. BOOST_MATH_BIG_CONSTANT(T, 53, 0.00840807615555585383007),
  319. BOOST_MATH_BIG_CONSTANT(T, 53, 0.00212825620914618649141),
  320. BOOST_MATH_BIG_CONSTANT(T, 53, 0.000250269961544794627958),
  321. BOOST_MATH_BIG_CONSTANT(T, 53, 0.113212406648847561139e-4),
  322. };
  323. static const T Q[] = {
  324. BOOST_MATH_BIG_CONSTANT(T, 53, 1.0),
  325. BOOST_MATH_BIG_CONSTANT(T, 53, 1.04217814166938418171),
  326. BOOST_MATH_BIG_CONSTANT(T, 53, 0.442597659481563127003),
  327. BOOST_MATH_BIG_CONSTANT(T, 53, 0.0958492726301061423444),
  328. BOOST_MATH_BIG_CONSTANT(T, 53, 0.0105982906484876531489),
  329. BOOST_MATH_BIG_CONSTANT(T, 53, 0.000479411269521714493907),
  330. };
  331. result = Y + tools::evaluate_polynomial(P, T(z - 3.5)) / tools::evaluate_polynomial(Q, T(z - 3.5));
  332. T hi, lo;
  333. int expon;
  334. hi = floor(ldexp(frexp(z, &expon), 26));
  335. hi = ldexp(hi, expon - 26);
  336. lo = z - hi;
  337. T sq = z * z;
  338. T err_sqr = ((hi * hi - sq) + 2 * hi * lo) + lo * lo;
  339. result *= exp(-sq) * exp(-err_sqr) / z;
  340. }
  341. else
  342. {
  343. // Max Error found at double precision = 2.997958e-17
  344. // Maximum Deviation Found: 2.860e-17
  345. // Expected Error Term: 2.859e-17
  346. // Maximum Relative Change in Control Points: 1.357e-05
  347. static const T Y = 0.5579090118408203125f;
  348. static const T P[] = {
  349. BOOST_MATH_BIG_CONSTANT(T, 53, 0.00628057170626964891937),
  350. BOOST_MATH_BIG_CONSTANT(T, 53, 0.0175389834052493308818),
  351. BOOST_MATH_BIG_CONSTANT(T, 53, -0.212652252872804219852),
  352. BOOST_MATH_BIG_CONSTANT(T, 53, -0.687717681153649930619),
  353. BOOST_MATH_BIG_CONSTANT(T, 53, -2.5518551727311523996),
  354. BOOST_MATH_BIG_CONSTANT(T, 53, -3.22729451764143718517),
  355. BOOST_MATH_BIG_CONSTANT(T, 53, -2.8175401114513378771),
  356. };
  357. static const T Q[] = {
  358. BOOST_MATH_BIG_CONSTANT(T, 53, 1.0),
  359. BOOST_MATH_BIG_CONSTANT(T, 53, 2.79257750980575282228),
  360. BOOST_MATH_BIG_CONSTANT(T, 53, 11.0567237927800161565),
  361. BOOST_MATH_BIG_CONSTANT(T, 53, 15.930646027911794143),
  362. BOOST_MATH_BIG_CONSTANT(T, 53, 22.9367376522880577224),
  363. BOOST_MATH_BIG_CONSTANT(T, 53, 13.5064170191802889145),
  364. BOOST_MATH_BIG_CONSTANT(T, 53, 5.48409182238641741584),
  365. };
  366. result = Y + tools::evaluate_polynomial(P, T(1 / z)) / tools::evaluate_polynomial(Q, T(1 / z));
  367. T hi, lo;
  368. int expon;
  369. hi = floor(ldexp(frexp(z, &expon), 26));
  370. hi = ldexp(hi, expon - 26);
  371. lo = z - hi;
  372. T sq = z * z;
  373. T err_sqr = ((hi * hi - sq) + 2 * hi * lo) + lo * lo;
  374. result *= exp(-sq) * exp(-err_sqr) / z;
  375. }
  376. }
  377. else
  378. {
  379. //
  380. // Any value of z larger than 28 will underflow to zero:
  381. //
  382. result = 0;
  383. invert = !invert;
  384. }
  385. if(invert)
  386. {
  387. result = 1 - result;
  388. }
  389. return result;
  390. } // template <class T, class Lanczos>T erf_imp(T z, bool invert, const Lanczos& l, const mpl::int_<53>& t)
  391. template <class T, class Policy>
  392. T erf_imp(T z, bool invert, const Policy& pol, const mpl::int_<64>& t)
  393. {
  394. BOOST_MATH_STD_USING
  395. BOOST_MATH_INSTRUMENT_CODE("64-bit precision erf_imp called");
  396. if(z < 0)
  397. {
  398. if(!invert)
  399. return -erf_imp(T(-z), invert, pol, t);
  400. else if(z < -0.5)
  401. return 2 - erf_imp(T(-z), invert, pol, t);
  402. else
  403. return 1 + erf_imp(T(-z), false, pol, t);
  404. }
  405. T result;
  406. //
  407. // Big bunch of selection statements now to pick which
  408. // implementation to use, try to put most likely options
  409. // first:
  410. //
  411. if(z < 0.5)
  412. {
  413. //
  414. // We're going to calculate erf:
  415. //
  416. if(z == 0)
  417. {
  418. result = 0;
  419. }
  420. else if(z < 1e-10)
  421. {
  422. static const T c = BOOST_MATH_BIG_CONSTANT(T, 64, 0.003379167095512573896158903121545171688);
  423. result = z * 1.125 + z * c;
  424. }
  425. else
  426. {
  427. // Max Error found at long double precision = 1.623299e-20
  428. // Maximum Deviation Found: 4.326e-22
  429. // Expected Error Term: -4.326e-22
  430. // Maximum Relative Change in Control Points: 1.474e-04
  431. static const T Y = 1.044948577880859375f;
  432. static const T P[] = {
  433. BOOST_MATH_BIG_CONSTANT(T, 64, 0.0834305892146531988966),
  434. BOOST_MATH_BIG_CONSTANT(T, 64, -0.338097283075565413695),
  435. BOOST_MATH_BIG_CONSTANT(T, 64, -0.0509602734406067204596),
  436. BOOST_MATH_BIG_CONSTANT(T, 64, -0.00904906346158537794396),
  437. BOOST_MATH_BIG_CONSTANT(T, 64, -0.000489468651464798669181),
  438. BOOST_MATH_BIG_CONSTANT(T, 64, -0.200305626366151877759e-4),
  439. };
  440. static const T Q[] = {
  441. BOOST_MATH_BIG_CONSTANT(T, 64, 1.0),
  442. BOOST_MATH_BIG_CONSTANT(T, 64, 0.455817300515875172439),
  443. BOOST_MATH_BIG_CONSTANT(T, 64, 0.0916537354356241792007),
  444. BOOST_MATH_BIG_CONSTANT(T, 64, 0.0102722652675910031202),
  445. BOOST_MATH_BIG_CONSTANT(T, 64, 0.000650511752687851548735),
  446. BOOST_MATH_BIG_CONSTANT(T, 64, 0.189532519105655496778e-4),
  447. };
  448. result = z * (Y + tools::evaluate_polynomial(P, T(z * z)) / tools::evaluate_polynomial(Q, T(z * z)));
  449. }
  450. }
  451. else if(invert ? (z < 110) : (z < 6.4f))
  452. {
  453. //
  454. // We'll be calculating erfc:
  455. //
  456. invert = !invert;
  457. if(z < 1.5)
  458. {
  459. // Max Error found at long double precision = 3.239590e-20
  460. // Maximum Deviation Found: 2.241e-20
  461. // Expected Error Term: -2.241e-20
  462. // Maximum Relative Change in Control Points: 5.110e-03
  463. static const T Y = 0.405935764312744140625f;
  464. static const T P[] = {
  465. BOOST_MATH_BIG_CONSTANT(T, 64, -0.0980905922162812031672),
  466. BOOST_MATH_BIG_CONSTANT(T, 64, 0.159989089922969141329),
  467. BOOST_MATH_BIG_CONSTANT(T, 64, 0.222359821619935712378),
  468. BOOST_MATH_BIG_CONSTANT(T, 64, 0.127303921703577362312),
  469. BOOST_MATH_BIG_CONSTANT(T, 64, 0.0384057530342762400273),
  470. BOOST_MATH_BIG_CONSTANT(T, 64, 0.00628431160851156719325),
  471. BOOST_MATH_BIG_CONSTANT(T, 64, 0.000441266654514391746428),
  472. BOOST_MATH_BIG_CONSTANT(T, 64, 0.266689068336295642561e-7),
  473. };
  474. static const T Q[] = {
  475. BOOST_MATH_BIG_CONSTANT(T, 64, 1.0),
  476. BOOST_MATH_BIG_CONSTANT(T, 64, 2.03237474985469469291),
  477. BOOST_MATH_BIG_CONSTANT(T, 64, 1.78355454954969405222),
  478. BOOST_MATH_BIG_CONSTANT(T, 64, 0.867940326293760578231),
  479. BOOST_MATH_BIG_CONSTANT(T, 64, 0.248025606990021698392),
  480. BOOST_MATH_BIG_CONSTANT(T, 64, 0.0396649631833002269861),
  481. BOOST_MATH_BIG_CONSTANT(T, 64, 0.00279220237309449026796),
  482. };
  483. result = Y + tools::evaluate_polynomial(P, T(z - 0.5f)) / tools::evaluate_polynomial(Q, T(z - 0.5f));
  484. T hi, lo;
  485. int expon;
  486. hi = floor(ldexp(frexp(z, &expon), 32));
  487. hi = ldexp(hi, expon - 32);
  488. lo = z - hi;
  489. T sq = z * z;
  490. T err_sqr = ((hi * hi - sq) + 2 * hi * lo) + lo * lo;
  491. result *= exp(-sq) * exp(-err_sqr) / z;
  492. }
  493. else if(z < 2.5)
  494. {
  495. // Max Error found at long double precision = 3.686211e-21
  496. // Maximum Deviation Found: 1.495e-21
  497. // Expected Error Term: -1.494e-21
  498. // Maximum Relative Change in Control Points: 1.793e-04
  499. static const T Y = 0.50672817230224609375f;
  500. static const T P[] = {
  501. BOOST_MATH_BIG_CONSTANT(T, 64, -0.024350047620769840217),
  502. BOOST_MATH_BIG_CONSTANT(T, 64, 0.0343522687935671451309),
  503. BOOST_MATH_BIG_CONSTANT(T, 64, 0.0505420824305544949541),
  504. BOOST_MATH_BIG_CONSTANT(T, 64, 0.0257479325917757388209),
  505. BOOST_MATH_BIG_CONSTANT(T, 64, 0.00669349844190354356118),
  506. BOOST_MATH_BIG_CONSTANT(T, 64, 0.00090807914416099524444),
  507. BOOST_MATH_BIG_CONSTANT(T, 64, 0.515917266698050027934e-4),
  508. };
  509. static const T Q[] = {
  510. BOOST_MATH_BIG_CONSTANT(T, 64, 1.0),
  511. BOOST_MATH_BIG_CONSTANT(T, 64, 1.71657861671930336344),
  512. BOOST_MATH_BIG_CONSTANT(T, 64, 1.26409634824280366218),
  513. BOOST_MATH_BIG_CONSTANT(T, 64, 0.512371437838969015941),
  514. BOOST_MATH_BIG_CONSTANT(T, 64, 0.120902623051120950935),
  515. BOOST_MATH_BIG_CONSTANT(T, 64, 0.0158027197831887485261),
  516. BOOST_MATH_BIG_CONSTANT(T, 64, 0.000897871370778031611439),
  517. };
  518. result = Y + tools::evaluate_polynomial(P, T(z - 1.5f)) / tools::evaluate_polynomial(Q, T(z - 1.5f));
  519. T hi, lo;
  520. int expon;
  521. hi = floor(ldexp(frexp(z, &expon), 32));
  522. hi = ldexp(hi, expon - 32);
  523. lo = z - hi;
  524. T sq = z * z;
  525. T err_sqr = ((hi * hi - sq) + 2 * hi * lo) + lo * lo;
  526. result *= exp(-sq) * exp(-err_sqr) / z;
  527. }
  528. else if(z < 4.5)
  529. {
  530. // Maximum Deviation Found: 1.107e-20
  531. // Expected Error Term: -1.106e-20
  532. // Maximum Relative Change in Control Points: 1.709e-04
  533. // Max Error found at long double precision = 1.446908e-20
  534. static const T Y = 0.5405750274658203125f;
  535. static const T P[] = {
  536. BOOST_MATH_BIG_CONSTANT(T, 64, 0.0029527671653097284033),
  537. BOOST_MATH_BIG_CONSTANT(T, 64, 0.0141853245895495604051),
  538. BOOST_MATH_BIG_CONSTANT(T, 64, 0.0104959584626432293901),
  539. BOOST_MATH_BIG_CONSTANT(T, 64, 0.00343963795976100077626),
  540. BOOST_MATH_BIG_CONSTANT(T, 64, 0.00059065441194877637899),
  541. BOOST_MATH_BIG_CONSTANT(T, 64, 0.523435380636174008685e-4),
  542. BOOST_MATH_BIG_CONSTANT(T, 64, 0.189896043050331257262e-5),
  543. };
  544. static const T Q[] = {
  545. BOOST_MATH_BIG_CONSTANT(T, 64, 1.0),
  546. BOOST_MATH_BIG_CONSTANT(T, 64, 1.19352160185285642574),
  547. BOOST_MATH_BIG_CONSTANT(T, 64, 0.603256964363454392857),
  548. BOOST_MATH_BIG_CONSTANT(T, 64, 0.165411142458540585835),
  549. BOOST_MATH_BIG_CONSTANT(T, 64, 0.0259729870946203166468),
  550. BOOST_MATH_BIG_CONSTANT(T, 64, 0.00221657568292893699158),
  551. BOOST_MATH_BIG_CONSTANT(T, 64, 0.804149464190309799804e-4),
  552. };
  553. result = Y + tools::evaluate_polynomial(P, T(z - 3.5f)) / tools::evaluate_polynomial(Q, T(z - 3.5f));
  554. T hi, lo;
  555. int expon;
  556. hi = floor(ldexp(frexp(z, &expon), 32));
  557. hi = ldexp(hi, expon - 32);
  558. lo = z - hi;
  559. T sq = z * z;
  560. T err_sqr = ((hi * hi - sq) + 2 * hi * lo) + lo * lo;
  561. result *= exp(-sq) * exp(-err_sqr) / z;
  562. }
  563. else
  564. {
  565. // Max Error found at long double precision = 7.961166e-21
  566. // Maximum Deviation Found: 6.677e-21
  567. // Expected Error Term: 6.676e-21
  568. // Maximum Relative Change in Control Points: 2.319e-05
  569. static const T Y = 0.55825519561767578125f;
  570. static const T P[] = {
  571. BOOST_MATH_BIG_CONSTANT(T, 64, 0.00593438793008050214106),
  572. BOOST_MATH_BIG_CONSTANT(T, 64, 0.0280666231009089713937),
  573. BOOST_MATH_BIG_CONSTANT(T, 64, -0.141597835204583050043),
  574. BOOST_MATH_BIG_CONSTANT(T, 64, -0.978088201154300548842),
  575. BOOST_MATH_BIG_CONSTANT(T, 64, -5.47351527796012049443),
  576. BOOST_MATH_BIG_CONSTANT(T, 64, -13.8677304660245326627),
  577. BOOST_MATH_BIG_CONSTANT(T, 64, -27.1274948720539821722),
  578. BOOST_MATH_BIG_CONSTANT(T, 64, -29.2545152747009461519),
  579. BOOST_MATH_BIG_CONSTANT(T, 64, -16.8865774499799676937),
  580. };
  581. static const T Q[] = {
  582. BOOST_MATH_BIG_CONSTANT(T, 64, 1.0),
  583. BOOST_MATH_BIG_CONSTANT(T, 64, 4.72948911186645394541),
  584. BOOST_MATH_BIG_CONSTANT(T, 64, 23.6750543147695749212),
  585. BOOST_MATH_BIG_CONSTANT(T, 64, 60.0021517335693186785),
  586. BOOST_MATH_BIG_CONSTANT(T, 64, 131.766251645149522868),
  587. BOOST_MATH_BIG_CONSTANT(T, 64, 178.167924971283482513),
  588. BOOST_MATH_BIG_CONSTANT(T, 64, 182.499390505915222699),
  589. BOOST_MATH_BIG_CONSTANT(T, 64, 104.365251479578577989),
  590. BOOST_MATH_BIG_CONSTANT(T, 64, 30.8365511891224291717),
  591. };
  592. result = Y + tools::evaluate_polynomial(P, T(1 / z)) / tools::evaluate_polynomial(Q, T(1 / z));
  593. T hi, lo;
  594. int expon;
  595. hi = floor(ldexp(frexp(z, &expon), 32));
  596. hi = ldexp(hi, expon - 32);
  597. lo = z - hi;
  598. T sq = z * z;
  599. T err_sqr = ((hi * hi - sq) + 2 * hi * lo) + lo * lo;
  600. result *= exp(-sq) * exp(-err_sqr) / z;
  601. }
  602. }
  603. else
  604. {
  605. //
  606. // Any value of z larger than 110 will underflow to zero:
  607. //
  608. result = 0;
  609. invert = !invert;
  610. }
  611. if(invert)
  612. {
  613. result = 1 - result;
  614. }
  615. return result;
  616. } // template <class T, class Lanczos>T erf_imp(T z, bool invert, const Lanczos& l, const mpl::int_<64>& t)
  617. template <class T, class Policy>
  618. T erf_imp(T z, bool invert, const Policy& pol, const mpl::int_<113>& t)
  619. {
  620. BOOST_MATH_STD_USING
  621. BOOST_MATH_INSTRUMENT_CODE("113-bit precision erf_imp called");
  622. if(z < 0)
  623. {
  624. if(!invert)
  625. return -erf_imp(T(-z), invert, pol, t);
  626. else if(z < -0.5)
  627. return 2 - erf_imp(T(-z), invert, pol, t);
  628. else
  629. return 1 + erf_imp(T(-z), false, pol, t);
  630. }
  631. T result;
  632. //
  633. // Big bunch of selection statements now to pick which
  634. // implementation to use, try to put most likely options
  635. // first:
  636. //
  637. if(z < 0.5)
  638. {
  639. //
  640. // We're going to calculate erf:
  641. //
  642. if(z == 0)
  643. {
  644. result = 0;
  645. }
  646. else if(z < 1e-20)
  647. {
  648. static const T c = BOOST_MATH_BIG_CONSTANT(T, 113, 0.003379167095512573896158903121545171688);
  649. result = z * 1.125 + z * c;
  650. }
  651. else
  652. {
  653. // Max Error found at long double precision = 2.342380e-35
  654. // Maximum Deviation Found: 6.124e-36
  655. // Expected Error Term: -6.124e-36
  656. // Maximum Relative Change in Control Points: 3.492e-10
  657. static const T Y = 1.0841522216796875f;
  658. static const T P[] = {
  659. BOOST_MATH_BIG_CONSTANT(T, 113, 0.0442269454158250738961589031215451778),
  660. BOOST_MATH_BIG_CONSTANT(T, 113, -0.35549265736002144875335323556961233),
  661. BOOST_MATH_BIG_CONSTANT(T, 113, -0.0582179564566667896225454670863270393),
  662. BOOST_MATH_BIG_CONSTANT(T, 113, -0.0112694696904802304229950538453123925),
  663. BOOST_MATH_BIG_CONSTANT(T, 113, -0.000805730648981801146251825329609079099),
  664. BOOST_MATH_BIG_CONSTANT(T, 113, -0.566304966591936566229702842075966273e-4),
  665. BOOST_MATH_BIG_CONSTANT(T, 113, -0.169655010425186987820201021510002265e-5),
  666. BOOST_MATH_BIG_CONSTANT(T, 113, -0.344448249920445916714548295433198544e-7),
  667. };
  668. static const T Q[] = {
  669. BOOST_MATH_BIG_CONSTANT(T, 113, 1.0),
  670. BOOST_MATH_BIG_CONSTANT(T, 113, 0.466542092785657604666906909196052522),
  671. BOOST_MATH_BIG_CONSTANT(T, 113, 0.100005087012526447295176964142107611),
  672. BOOST_MATH_BIG_CONSTANT(T, 113, 0.0128341535890117646540050072234142603),
  673. BOOST_MATH_BIG_CONSTANT(T, 113, 0.00107150448466867929159660677016658186),
  674. BOOST_MATH_BIG_CONSTANT(T, 113, 0.586168368028999183607733369248338474e-4),
  675. BOOST_MATH_BIG_CONSTANT(T, 113, 0.196230608502104324965623171516808796e-5),
  676. BOOST_MATH_BIG_CONSTANT(T, 113, 0.313388521582925207734229967907890146e-7),
  677. };
  678. result = z * (Y + tools::evaluate_polynomial(P, T(z * z)) / tools::evaluate_polynomial(Q, T(z * z)));
  679. }
  680. }
  681. else if(invert ? (z < 110) : (z < 8.65f))
  682. {
  683. //
  684. // We'll be calculating erfc:
  685. //
  686. invert = !invert;
  687. if(z < 1)
  688. {
  689. // Max Error found at long double precision = 3.246278e-35
  690. // Maximum Deviation Found: 1.388e-35
  691. // Expected Error Term: 1.387e-35
  692. // Maximum Relative Change in Control Points: 6.127e-05
  693. static const T Y = 0.371877193450927734375f;
  694. static const T P[] = {
  695. BOOST_MATH_BIG_CONSTANT(T, 113, -0.0640320213544647969396032886581290455),
  696. BOOST_MATH_BIG_CONSTANT(T, 113, 0.200769874440155895637857443946706731),
  697. BOOST_MATH_BIG_CONSTANT(T, 113, 0.378447199873537170666487408805779826),
  698. BOOST_MATH_BIG_CONSTANT(T, 113, 0.30521399466465939450398642044975127),
  699. BOOST_MATH_BIG_CONSTANT(T, 113, 0.146890026406815277906781824723458196),
  700. BOOST_MATH_BIG_CONSTANT(T, 113, 0.0464837937749539978247589252732769567),
  701. BOOST_MATH_BIG_CONSTANT(T, 113, 0.00987895759019540115099100165904822903),
  702. BOOST_MATH_BIG_CONSTANT(T, 113, 0.00137507575429025512038051025154301132),
  703. BOOST_MATH_BIG_CONSTANT(T, 113, 0.0001144764551085935580772512359680516),
  704. BOOST_MATH_BIG_CONSTANT(T, 113, 0.436544865032836914773944382339900079e-5),
  705. };
  706. static const T Q[] = {
  707. BOOST_MATH_BIG_CONSTANT(T, 113, 1.0),
  708. BOOST_MATH_BIG_CONSTANT(T, 113, 2.47651182872457465043733800302427977),
  709. BOOST_MATH_BIG_CONSTANT(T, 113, 2.78706486002517996428836400245547955),
  710. BOOST_MATH_BIG_CONSTANT(T, 113, 1.87295924621659627926365005293130693),
  711. BOOST_MATH_BIG_CONSTANT(T, 113, 0.829375825174365625428280908787261065),
  712. BOOST_MATH_BIG_CONSTANT(T, 113, 0.251334771307848291593780143950311514),
  713. BOOST_MATH_BIG_CONSTANT(T, 113, 0.0522110268876176186719436765734722473),
  714. BOOST_MATH_BIG_CONSTANT(T, 113, 0.00718332151250963182233267040106902368),
  715. BOOST_MATH_BIG_CONSTANT(T, 113, 0.000595279058621482041084986219276392459),
  716. BOOST_MATH_BIG_CONSTANT(T, 113, 0.226988669466501655990637599399326874e-4),
  717. BOOST_MATH_BIG_CONSTANT(T, 113, 0.270666232259029102353426738909226413e-10),
  718. };
  719. result = Y + tools::evaluate_polynomial(P, T(z - 0.5f)) / tools::evaluate_polynomial(Q, T(z - 0.5f));
  720. T hi, lo;
  721. int expon;
  722. hi = floor(ldexp(frexp(z, &expon), 56));
  723. hi = ldexp(hi, expon - 56);
  724. lo = z - hi;
  725. T sq = z * z;
  726. T err_sqr = ((hi * hi - sq) + 2 * hi * lo) + lo * lo;
  727. result *= exp(-sq) * exp(-err_sqr) / z;
  728. }
  729. else if(z < 1.5)
  730. {
  731. // Max Error found at long double precision = 2.215785e-35
  732. // Maximum Deviation Found: 1.539e-35
  733. // Expected Error Term: 1.538e-35
  734. // Maximum Relative Change in Control Points: 6.104e-05
  735. static const T Y = 0.45658016204833984375f;
  736. static const T P[] = {
  737. BOOST_MATH_BIG_CONSTANT(T, 113, -0.0289965858925328393392496555094848345),
  738. BOOST_MATH_BIG_CONSTANT(T, 113, 0.0868181194868601184627743162571779226),
  739. BOOST_MATH_BIG_CONSTANT(T, 113, 0.169373435121178901746317404936356745),
  740. BOOST_MATH_BIG_CONSTANT(T, 113, 0.13350446515949251201104889028133486),
  741. BOOST_MATH_BIG_CONSTANT(T, 113, 0.0617447837290183627136837688446313313),
  742. BOOST_MATH_BIG_CONSTANT(T, 113, 0.0185618495228251406703152962489700468),
  743. BOOST_MATH_BIG_CONSTANT(T, 113, 0.00371949406491883508764162050169531013),
  744. BOOST_MATH_BIG_CONSTANT(T, 113, 0.000485121708792921297742105775823900772),
  745. BOOST_MATH_BIG_CONSTANT(T, 113, 0.376494706741453489892108068231400061e-4),
  746. BOOST_MATH_BIG_CONSTANT(T, 113, 0.133166058052466262415271732172490045e-5),
  747. };
  748. static const T Q[] = {
  749. BOOST_MATH_BIG_CONSTANT(T, 113, 1.0),
  750. BOOST_MATH_BIG_CONSTANT(T, 113, 2.32970330146503867261275580968135126),
  751. BOOST_MATH_BIG_CONSTANT(T, 113, 2.46325715420422771961250513514928746),
  752. BOOST_MATH_BIG_CONSTANT(T, 113, 1.55307882560757679068505047390857842),
  753. BOOST_MATH_BIG_CONSTANT(T, 113, 0.644274289865972449441174485441409076),
  754. BOOST_MATH_BIG_CONSTANT(T, 113, 0.182609091063258208068606847453955649),
  755. BOOST_MATH_BIG_CONSTANT(T, 113, 0.0354171651271241474946129665801606795),
  756. BOOST_MATH_BIG_CONSTANT(T, 113, 0.00454060370165285246451879969534083997),
  757. BOOST_MATH_BIG_CONSTANT(T, 113, 0.000349871943711566546821198612518656486),
  758. BOOST_MATH_BIG_CONSTANT(T, 113, 0.123749319840299552925421880481085392e-4),
  759. };
  760. result = Y + tools::evaluate_polynomial(P, T(z - 1.0f)) / tools::evaluate_polynomial(Q, T(z - 1.0f));
  761. T hi, lo;
  762. int expon;
  763. hi = floor(ldexp(frexp(z, &expon), 56));
  764. hi = ldexp(hi, expon - 56);
  765. lo = z - hi;
  766. T sq = z * z;
  767. T err_sqr = ((hi * hi - sq) + 2 * hi * lo) + lo * lo;
  768. result *= exp(-sq) * exp(-err_sqr) / z;
  769. }
  770. else if(z < 2.25)
  771. {
  772. // Maximum Deviation Found: 1.418e-35
  773. // Expected Error Term: 1.418e-35
  774. // Maximum Relative Change in Control Points: 1.316e-04
  775. // Max Error found at long double precision = 1.998462e-35
  776. static const T Y = 0.50250148773193359375f;
  777. static const T P[] = {
  778. BOOST_MATH_BIG_CONSTANT(T, 113, -0.0201233630504573402185161184151016606),
  779. BOOST_MATH_BIG_CONSTANT(T, 113, 0.0331864357574860196516686996302305002),
  780. BOOST_MATH_BIG_CONSTANT(T, 113, 0.0716562720864787193337475444413405461),
  781. BOOST_MATH_BIG_CONSTANT(T, 113, 0.0545835322082103985114927569724880658),
  782. BOOST_MATH_BIG_CONSTANT(T, 113, 0.0236692635189696678976549720784989593),
  783. BOOST_MATH_BIG_CONSTANT(T, 113, 0.00656970902163248872837262539337601845),
  784. BOOST_MATH_BIG_CONSTANT(T, 113, 0.00120282643299089441390490459256235021),
  785. BOOST_MATH_BIG_CONSTANT(T, 113, 0.000142123229065182650020762792081622986),
  786. BOOST_MATH_BIG_CONSTANT(T, 113, 0.991531438367015135346716277792989347e-5),
  787. BOOST_MATH_BIG_CONSTANT(T, 113, 0.312857043762117596999398067153076051e-6),
  788. };
  789. static const T Q[] = {
  790. BOOST_MATH_BIG_CONSTANT(T, 113, 1.0),
  791. BOOST_MATH_BIG_CONSTANT(T, 113, 2.13506082409097783827103424943508554),
  792. BOOST_MATH_BIG_CONSTANT(T, 113, 2.06399257267556230937723190496806215),
  793. BOOST_MATH_BIG_CONSTANT(T, 113, 1.18678481279932541314830499880691109),
  794. BOOST_MATH_BIG_CONSTANT(T, 113, 0.447733186643051752513538142316799562),
  795. BOOST_MATH_BIG_CONSTANT(T, 113, 0.11505680005657879437196953047542148),
  796. BOOST_MATH_BIG_CONSTANT(T, 113, 0.020163993632192726170219663831914034),
  797. BOOST_MATH_BIG_CONSTANT(T, 113, 0.00232708971840141388847728782209730585),
  798. BOOST_MATH_BIG_CONSTANT(T, 113, 0.000160733201627963528519726484608224112),
  799. BOOST_MATH_BIG_CONSTANT(T, 113, 0.507158721790721802724402992033269266e-5),
  800. BOOST_MATH_BIG_CONSTANT(T, 113, 0.18647774409821470950544212696270639e-12),
  801. };
  802. result = Y + tools::evaluate_polynomial(P, T(z - 1.5f)) / tools::evaluate_polynomial(Q, T(z - 1.5f));
  803. T hi, lo;
  804. int expon;
  805. hi = floor(ldexp(frexp(z, &expon), 56));
  806. hi = ldexp(hi, expon - 56);
  807. lo = z - hi;
  808. T sq = z * z;
  809. T err_sqr = ((hi * hi - sq) + 2 * hi * lo) + lo * lo;
  810. result *= exp(-sq) * exp(-err_sqr) / z;
  811. }
  812. else if (z < 3)
  813. {
  814. // Maximum Deviation Found: 3.575e-36
  815. // Expected Error Term: 3.575e-36
  816. // Maximum Relative Change in Control Points: 7.103e-05
  817. // Max Error found at long double precision = 5.794737e-36
  818. static const T Y = 0.52896785736083984375f;
  819. static const T P[] = {
  820. BOOST_MATH_BIG_CONSTANT(T, 113, -0.00902152521745813634562524098263360074),
  821. BOOST_MATH_BIG_CONSTANT(T, 113, 0.0145207142776691539346923710537580927),
  822. BOOST_MATH_BIG_CONSTANT(T, 113, 0.0301681239582193983824211995978678571),
  823. BOOST_MATH_BIG_CONSTANT(T, 113, 0.0215548540823305814379020678660434461),
  824. BOOST_MATH_BIG_CONSTANT(T, 113, 0.00864683476267958365678294164340749949),
  825. BOOST_MATH_BIG_CONSTANT(T, 113, 0.00219693096885585491739823283511049902),
  826. BOOST_MATH_BIG_CONSTANT(T, 113, 0.000364961639163319762492184502159894371),
  827. BOOST_MATH_BIG_CONSTANT(T, 113, 0.388174251026723752769264051548703059e-4),
  828. BOOST_MATH_BIG_CONSTANT(T, 113, 0.241918026931789436000532513553594321e-5),
  829. BOOST_MATH_BIG_CONSTANT(T, 113, 0.676586625472423508158937481943649258e-7),
  830. };
  831. static const T Q[] = {
  832. BOOST_MATH_BIG_CONSTANT(T, 113, 1.0),
  833. BOOST_MATH_BIG_CONSTANT(T, 113, 1.93669171363907292305550231764920001),
  834. BOOST_MATH_BIG_CONSTANT(T, 113, 1.69468476144051356810672506101377494),
  835. BOOST_MATH_BIG_CONSTANT(T, 113, 0.880023580986436640372794392579985511),
  836. BOOST_MATH_BIG_CONSTANT(T, 113, 0.299099106711315090710836273697708402),
  837. BOOST_MATH_BIG_CONSTANT(T, 113, 0.0690593962363545715997445583603382337),
  838. BOOST_MATH_BIG_CONSTANT(T, 113, 0.0108427016361318921960863149875360222),
  839. BOOST_MATH_BIG_CONSTANT(T, 113, 0.00111747247208044534520499324234317695),
  840. BOOST_MATH_BIG_CONSTANT(T, 113, 0.686843205749767250666787987163701209e-4),
  841. BOOST_MATH_BIG_CONSTANT(T, 113, 0.192093541425429248675532015101904262e-5),
  842. };
  843. result = Y + tools::evaluate_polynomial(P, T(z - 2.25f)) / tools::evaluate_polynomial(Q, T(z - 2.25f));
  844. T hi, lo;
  845. int expon;
  846. hi = floor(ldexp(frexp(z, &expon), 56));
  847. hi = ldexp(hi, expon - 56);
  848. lo = z - hi;
  849. T sq = z * z;
  850. T err_sqr = ((hi * hi - sq) + 2 * hi * lo) + lo * lo;
  851. result *= exp(-sq) * exp(-err_sqr) / z;
  852. }
  853. else if(z < 3.5)
  854. {
  855. // Maximum Deviation Found: 8.126e-37
  856. // Expected Error Term: -8.126e-37
  857. // Maximum Relative Change in Control Points: 1.363e-04
  858. // Max Error found at long double precision = 1.747062e-36
  859. static const T Y = 0.54037380218505859375f;
  860. static const T P[] = {
  861. BOOST_MATH_BIG_CONSTANT(T, 113, -0.0033703486408887424921155540591370375),
  862. BOOST_MATH_BIG_CONSTANT(T, 113, 0.0104948043110005245215286678898115811),
  863. BOOST_MATH_BIG_CONSTANT(T, 113, 0.0148530118504000311502310457390417795),
  864. BOOST_MATH_BIG_CONSTANT(T, 113, 0.00816693029245443090102738825536188916),
  865. BOOST_MATH_BIG_CONSTANT(T, 113, 0.00249716579989140882491939681805594585),
  866. BOOST_MATH_BIG_CONSTANT(T, 113, 0.0004655591010047353023978045800916647),
  867. BOOST_MATH_BIG_CONSTANT(T, 113, 0.531129557920045295895085236636025323e-4),
  868. BOOST_MATH_BIG_CONSTANT(T, 113, 0.343526765122727069515775194111741049e-5),
  869. BOOST_MATH_BIG_CONSTANT(T, 113, 0.971120407556888763695313774578711839e-7),
  870. };
  871. static const T Q[] = {
  872. BOOST_MATH_BIG_CONSTANT(T, 113, 1.0),
  873. BOOST_MATH_BIG_CONSTANT(T, 113, 1.59911256167540354915906501335919317),
  874. BOOST_MATH_BIG_CONSTANT(T, 113, 1.136006830764025173864831382946934),
  875. BOOST_MATH_BIG_CONSTANT(T, 113, 0.468565867990030871678574840738423023),
  876. BOOST_MATH_BIG_CONSTANT(T, 113, 0.122821824954470343413956476900662236),
  877. BOOST_MATH_BIG_CONSTANT(T, 113, 0.0209670914950115943338996513330141633),
  878. BOOST_MATH_BIG_CONSTANT(T, 113, 0.00227845718243186165620199012883547257),
  879. BOOST_MATH_BIG_CONSTANT(T, 113, 0.000144243326443913171313947613547085553),
  880. BOOST_MATH_BIG_CONSTANT(T, 113, 0.407763415954267700941230249989140046e-5),
  881. };
  882. result = Y + tools::evaluate_polynomial(P, T(z - 3.0f)) / tools::evaluate_polynomial(Q, T(z - 3.0f));
  883. T hi, lo;
  884. int expon;
  885. hi = floor(ldexp(frexp(z, &expon), 56));
  886. hi = ldexp(hi, expon - 56);
  887. lo = z - hi;
  888. T sq = z * z;
  889. T err_sqr = ((hi * hi - sq) + 2 * hi * lo) + lo * lo;
  890. result *= exp(-sq) * exp(-err_sqr) / z;
  891. }
  892. else if(z < 5.5)
  893. {
  894. // Maximum Deviation Found: 5.804e-36
  895. // Expected Error Term: -5.803e-36
  896. // Maximum Relative Change in Control Points: 2.475e-05
  897. // Max Error found at long double precision = 1.349545e-35
  898. static const T Y = 0.55000019073486328125f;
  899. static const T P[] = {
  900. BOOST_MATH_BIG_CONSTANT(T, 113, 0.00118142849742309772151454518093813615),
  901. BOOST_MATH_BIG_CONSTANT(T, 113, 0.0072201822885703318172366893469382745),
  902. BOOST_MATH_BIG_CONSTANT(T, 113, 0.0078782276276860110721875733778481505),
  903. BOOST_MATH_BIG_CONSTANT(T, 113, 0.00418229166204362376187593976656261146),
  904. BOOST_MATH_BIG_CONSTANT(T, 113, 0.00134198400587769200074194304298642705),
  905. BOOST_MATH_BIG_CONSTANT(T, 113, 0.000283210387078004063264777611497435572),
  906. BOOST_MATH_BIG_CONSTANT(T, 113, 0.405687064094911866569295610914844928e-4),
  907. BOOST_MATH_BIG_CONSTANT(T, 113, 0.39348283801568113807887364414008292e-5),
  908. BOOST_MATH_BIG_CONSTANT(T, 113, 0.248798540917787001526976889284624449e-6),
  909. BOOST_MATH_BIG_CONSTANT(T, 113, 0.929502490223452372919607105387474751e-8),
  910. BOOST_MATH_BIG_CONSTANT(T, 113, 0.156161469668275442569286723236274457e-9),
  911. };
  912. static const T Q[] = {
  913. BOOST_MATH_BIG_CONSTANT(T, 113, 1.0),
  914. BOOST_MATH_BIG_CONSTANT(T, 113, 1.52955245103668419479878456656709381),
  915. BOOST_MATH_BIG_CONSTANT(T, 113, 1.06263944820093830054635017117417064),
  916. BOOST_MATH_BIG_CONSTANT(T, 113, 0.441684612681607364321013134378316463),
  917. BOOST_MATH_BIG_CONSTANT(T, 113, 0.121665258426166960049773715928906382),
  918. BOOST_MATH_BIG_CONSTANT(T, 113, 0.0232134512374747691424978642874321434),
  919. BOOST_MATH_BIG_CONSTANT(T, 113, 0.00310778180686296328582860464875562636),
  920. BOOST_MATH_BIG_CONSTANT(T, 113, 0.000288361770756174705123674838640161693),
  921. BOOST_MATH_BIG_CONSTANT(T, 113, 0.177529187194133944622193191942300132e-4),
  922. BOOST_MATH_BIG_CONSTANT(T, 113, 0.655068544833064069223029299070876623e-6),
  923. BOOST_MATH_BIG_CONSTANT(T, 113, 0.11005507545746069573608988651927452e-7),
  924. };
  925. result = Y + tools::evaluate_polynomial(P, T(z - 4.5f)) / tools::evaluate_polynomial(Q, T(z - 4.5f));
  926. T hi, lo;
  927. int expon;
  928. hi = floor(ldexp(frexp(z, &expon), 56));
  929. hi = ldexp(hi, expon - 56);
  930. lo = z - hi;
  931. T sq = z * z;
  932. T err_sqr = ((hi * hi - sq) + 2 * hi * lo) + lo * lo;
  933. result *= exp(-sq) * exp(-err_sqr) / z;
  934. }
  935. else if(z < 7.5)
  936. {
  937. // Maximum Deviation Found: 1.007e-36
  938. // Expected Error Term: 1.007e-36
  939. // Maximum Relative Change in Control Points: 1.027e-03
  940. // Max Error found at long double precision = 2.646420e-36
  941. static const T Y = 0.5574436187744140625f;
  942. static const T P[] = {
  943. BOOST_MATH_BIG_CONSTANT(T, 113, 0.000293236907400849056269309713064107674),
  944. BOOST_MATH_BIG_CONSTANT(T, 113, 0.00225110719535060642692275221961480162),
  945. BOOST_MATH_BIG_CONSTANT(T, 113, 0.00190984458121502831421717207849429799),
  946. BOOST_MATH_BIG_CONSTANT(T, 113, 0.000747757733460111743833929141001680706),
  947. BOOST_MATH_BIG_CONSTANT(T, 113, 0.000170663175280949889583158597373928096),
  948. BOOST_MATH_BIG_CONSTANT(T, 113, 0.246441188958013822253071608197514058e-4),
  949. BOOST_MATH_BIG_CONSTANT(T, 113, 0.229818000860544644974205957895688106e-5),
  950. BOOST_MATH_BIG_CONSTANT(T, 113, 0.134886977703388748488480980637704864e-6),
  951. BOOST_MATH_BIG_CONSTANT(T, 113, 0.454764611880548962757125070106650958e-8),
  952. BOOST_MATH_BIG_CONSTANT(T, 113, 0.673002744115866600294723141176820155e-10),
  953. };
  954. static const T Q[] = {
  955. BOOST_MATH_BIG_CONSTANT(T, 113, 1.0),
  956. BOOST_MATH_BIG_CONSTANT(T, 113, 1.12843690320861239631195353379313367),
  957. BOOST_MATH_BIG_CONSTANT(T, 113, 0.569900657061622955362493442186537259),
  958. BOOST_MATH_BIG_CONSTANT(T, 113, 0.169094404206844928112348730277514273),
  959. BOOST_MATH_BIG_CONSTANT(T, 113, 0.0324887449084220415058158657252147063),
  960. BOOST_MATH_BIG_CONSTANT(T, 113, 0.00419252877436825753042680842608219552),
  961. BOOST_MATH_BIG_CONSTANT(T, 113, 0.00036344133176118603523976748563178578),
  962. BOOST_MATH_BIG_CONSTANT(T, 113, 0.204123895931375107397698245752850347e-4),
  963. BOOST_MATH_BIG_CONSTANT(T, 113, 0.674128352521481412232785122943508729e-6),
  964. BOOST_MATH_BIG_CONSTANT(T, 113, 0.997637501418963696542159244436245077e-8),
  965. };
  966. result = Y + tools::evaluate_polynomial(P, T(z - 6.5f)) / tools::evaluate_polynomial(Q, T(z - 6.5f));
  967. T hi, lo;
  968. int expon;
  969. hi = floor(ldexp(frexp(z, &expon), 56));
  970. hi = ldexp(hi, expon - 56);
  971. lo = z - hi;
  972. T sq = z * z;
  973. T err_sqr = ((hi * hi - sq) + 2 * hi * lo) + lo * lo;
  974. result *= exp(-sq) * exp(-err_sqr) / z;
  975. }
  976. else if(z < 11.5)
  977. {
  978. // Maximum Deviation Found: 8.380e-36
  979. // Expected Error Term: 8.380e-36
  980. // Maximum Relative Change in Control Points: 2.632e-06
  981. // Max Error found at long double precision = 9.849522e-36
  982. static const T Y = 0.56083202362060546875f;
  983. static const T P[] = {
  984. BOOST_MATH_BIG_CONSTANT(T, 113, 0.000282420728751494363613829834891390121),
  985. BOOST_MATH_BIG_CONSTANT(T, 113, 0.00175387065018002823433704079355125161),
  986. BOOST_MATH_BIG_CONSTANT(T, 113, 0.0021344978564889819420775336322920375),
  987. BOOST_MATH_BIG_CONSTANT(T, 113, 0.00124151356560137532655039683963075661),
  988. BOOST_MATH_BIG_CONSTANT(T, 113, 0.000423600733566948018555157026862139644),
  989. BOOST_MATH_BIG_CONSTANT(T, 113, 0.914030340865175237133613697319509698e-4),
  990. BOOST_MATH_BIG_CONSTANT(T, 113, 0.126999927156823363353809747017945494e-4),
  991. BOOST_MATH_BIG_CONSTANT(T, 113, 0.110610959842869849776179749369376402e-5),
  992. BOOST_MATH_BIG_CONSTANT(T, 113, 0.55075079477173482096725348704634529e-7),
  993. BOOST_MATH_BIG_CONSTANT(T, 113, 0.119735694018906705225870691331543806e-8),
  994. };
  995. static const T Q[] = {
  996. BOOST_MATH_BIG_CONSTANT(T, 113, 1.0),
  997. BOOST_MATH_BIG_CONSTANT(T, 113, 1.69889613396167354566098060039549882),
  998. BOOST_MATH_BIG_CONSTANT(T, 113, 1.28824647372749624464956031163282674),
  999. BOOST_MATH_BIG_CONSTANT(T, 113, 0.572297795434934493541628008224078717),
  1000. BOOST_MATH_BIG_CONSTANT(T, 113, 0.164157697425571712377043857240773164),
  1001. BOOST_MATH_BIG_CONSTANT(T, 113, 0.0315311145224594430281219516531649562),
  1002. BOOST_MATH_BIG_CONSTANT(T, 113, 0.00405588922155632380812945849777127458),
  1003. BOOST_MATH_BIG_CONSTANT(T, 113, 0.000336929033691445666232029762868642417),
  1004. BOOST_MATH_BIG_CONSTANT(T, 113, 0.164033049810404773469413526427932109e-4),
  1005. BOOST_MATH_BIG_CONSTANT(T, 113, 0.356615210500531410114914617294694857e-6),
  1006. };
  1007. result = Y + tools::evaluate_polynomial(P, T(z / 2 - 4.75f)) / tools::evaluate_polynomial(Q, T(z / 2 - 4.75f));
  1008. T hi, lo;
  1009. int expon;
  1010. hi = floor(ldexp(frexp(z, &expon), 56));
  1011. hi = ldexp(hi, expon - 56);
  1012. lo = z - hi;
  1013. T sq = z * z;
  1014. T err_sqr = ((hi * hi - sq) + 2 * hi * lo) + lo * lo;
  1015. result *= exp(-sq) * exp(-err_sqr) / z;
  1016. }
  1017. else
  1018. {
  1019. // Maximum Deviation Found: 1.132e-35
  1020. // Expected Error Term: -1.132e-35
  1021. // Maximum Relative Change in Control Points: 4.674e-04
  1022. // Max Error found at long double precision = 1.162590e-35
  1023. static const T Y = 0.5632686614990234375f;
  1024. static const T P[] = {
  1025. BOOST_MATH_BIG_CONSTANT(T, 113, 0.000920922048732849448079451574171836943),
  1026. BOOST_MATH_BIG_CONSTANT(T, 113, 0.00321439044532288750501700028748922439),
  1027. BOOST_MATH_BIG_CONSTANT(T, 113, -0.250455263029390118657884864261823431),
  1028. BOOST_MATH_BIG_CONSTANT(T, 113, -0.906807635364090342031792404764598142),
  1029. BOOST_MATH_BIG_CONSTANT(T, 113, -8.92233572835991735876688745989985565),
  1030. BOOST_MATH_BIG_CONSTANT(T, 113, -21.7797433494422564811782116907878495),
  1031. BOOST_MATH_BIG_CONSTANT(T, 113, -91.1451915251976354349734589601171659),
  1032. BOOST_MATH_BIG_CONSTANT(T, 113, -144.1279109655993927069052125017673),
  1033. BOOST_MATH_BIG_CONSTANT(T, 113, -313.845076581796338665519022313775589),
  1034. BOOST_MATH_BIG_CONSTANT(T, 113, -273.11378811923343424081101235736475),
  1035. BOOST_MATH_BIG_CONSTANT(T, 113, -271.651566205951067025696102600443452),
  1036. BOOST_MATH_BIG_CONSTANT(T, 113, -60.0530577077238079968843307523245547),
  1037. };
  1038. static const T Q[] = {
  1039. BOOST_MATH_BIG_CONSTANT(T, 113, 1.0),
  1040. BOOST_MATH_BIG_CONSTANT(T, 113, 3.49040448075464744191022350947892036),
  1041. BOOST_MATH_BIG_CONSTANT(T, 113, 34.3563592467165971295915749548313227),
  1042. BOOST_MATH_BIG_CONSTANT(T, 113, 84.4993232033879023178285731843850461),
  1043. BOOST_MATH_BIG_CONSTANT(T, 113, 376.005865281206894120659401340373818),
  1044. BOOST_MATH_BIG_CONSTANT(T, 113, 629.95369438888946233003926191755125),
  1045. BOOST_MATH_BIG_CONSTANT(T, 113, 1568.35771983533158591604513304269098),
  1046. BOOST_MATH_BIG_CONSTANT(T, 113, 1646.02452040831961063640827116581021),
  1047. BOOST_MATH_BIG_CONSTANT(T, 113, 2299.96860633240298708910425594484895),
  1048. BOOST_MATH_BIG_CONSTANT(T, 113, 1222.73204392037452750381340219906374),
  1049. BOOST_MATH_BIG_CONSTANT(T, 113, 799.359797306084372350264298361110448),
  1050. BOOST_MATH_BIG_CONSTANT(T, 113, 72.7415265778588087243442792401576737),
  1051. };
  1052. result = Y + tools::evaluate_polynomial(P, T(1 / z)) / tools::evaluate_polynomial(Q, T(1 / z));
  1053. T hi, lo;
  1054. int expon;
  1055. hi = floor(ldexp(frexp(z, &expon), 56));
  1056. hi = ldexp(hi, expon - 56);
  1057. lo = z - hi;
  1058. T sq = z * z;
  1059. T err_sqr = ((hi * hi - sq) + 2 * hi * lo) + lo * lo;
  1060. result *= exp(-sq) * exp(-err_sqr) / z;
  1061. }
  1062. }
  1063. else
  1064. {
  1065. //
  1066. // Any value of z larger than 110 will underflow to zero:
  1067. //
  1068. result = 0;
  1069. invert = !invert;
  1070. }
  1071. if(invert)
  1072. {
  1073. result = 1 - result;
  1074. }
  1075. return result;
  1076. } // template <class T, class Lanczos>T erf_imp(T z, bool invert, const Lanczos& l, const mpl::int_<113>& t)
  1077. template <class T, class Policy, class tag>
  1078. struct erf_initializer
  1079. {
  1080. struct init
  1081. {
  1082. init()
  1083. {
  1084. do_init(tag());
  1085. }
  1086. static void do_init(const mpl::int_<0>&){}
  1087. static void do_init(const mpl::int_<53>&)
  1088. {
  1089. boost::math::erf(static_cast<T>(1e-12), Policy());
  1090. boost::math::erf(static_cast<T>(0.25), Policy());
  1091. boost::math::erf(static_cast<T>(1.25), Policy());
  1092. boost::math::erf(static_cast<T>(2.25), Policy());
  1093. boost::math::erf(static_cast<T>(4.25), Policy());
  1094. boost::math::erf(static_cast<T>(5.25), Policy());
  1095. }
  1096. static void do_init(const mpl::int_<64>&)
  1097. {
  1098. boost::math::erf(static_cast<T>(1e-12), Policy());
  1099. boost::math::erf(static_cast<T>(0.25), Policy());
  1100. boost::math::erf(static_cast<T>(1.25), Policy());
  1101. boost::math::erf(static_cast<T>(2.25), Policy());
  1102. boost::math::erf(static_cast<T>(4.25), Policy());
  1103. boost::math::erf(static_cast<T>(5.25), Policy());
  1104. }
  1105. static void do_init(const mpl::int_<113>&)
  1106. {
  1107. boost::math::erf(static_cast<T>(1e-22), Policy());
  1108. boost::math::erf(static_cast<T>(0.25), Policy());
  1109. boost::math::erf(static_cast<T>(1.25), Policy());
  1110. boost::math::erf(static_cast<T>(2.125), Policy());
  1111. boost::math::erf(static_cast<T>(2.75), Policy());
  1112. boost::math::erf(static_cast<T>(3.25), Policy());
  1113. boost::math::erf(static_cast<T>(5.25), Policy());
  1114. boost::math::erf(static_cast<T>(7.25), Policy());
  1115. boost::math::erf(static_cast<T>(11.25), Policy());
  1116. boost::math::erf(static_cast<T>(12.5), Policy());
  1117. }
  1118. void force_instantiate()const{}
  1119. };
  1120. static const init initializer;
  1121. static void force_instantiate()
  1122. {
  1123. initializer.force_instantiate();
  1124. }
  1125. };
  1126. template <class T, class Policy, class tag>
  1127. const typename erf_initializer<T, Policy, tag>::init erf_initializer<T, Policy, tag>::initializer;
  1128. } // namespace detail
  1129. template <class T, class Policy>
  1130. inline typename tools::promote_args<T>::type erf(T z, const Policy& /* pol */)
  1131. {
  1132. typedef typename tools::promote_args<T>::type result_type;
  1133. typedef typename policies::evaluation<result_type, Policy>::type value_type;
  1134. typedef typename policies::precision<result_type, Policy>::type precision_type;
  1135. typedef typename policies::normalise<
  1136. Policy,
  1137. policies::promote_float<false>,
  1138. policies::promote_double<false>,
  1139. policies::discrete_quantile<>,
  1140. policies::assert_undefined<> >::type forwarding_policy;
  1141. BOOST_MATH_INSTRUMENT_CODE("result_type = " << typeid(result_type).name());
  1142. BOOST_MATH_INSTRUMENT_CODE("value_type = " << typeid(value_type).name());
  1143. BOOST_MATH_INSTRUMENT_CODE("precision_type = " << typeid(precision_type).name());
  1144. typedef typename mpl::if_<
  1145. mpl::less_equal<precision_type, mpl::int_<0> >,
  1146. mpl::int_<0>,
  1147. typename mpl::if_<
  1148. mpl::less_equal<precision_type, mpl::int_<53> >,
  1149. mpl::int_<53>, // double
  1150. typename mpl::if_<
  1151. mpl::less_equal<precision_type, mpl::int_<64> >,
  1152. mpl::int_<64>, // 80-bit long double
  1153. typename mpl::if_<
  1154. mpl::less_equal<precision_type, mpl::int_<113> >,
  1155. mpl::int_<113>, // 128-bit long double
  1156. mpl::int_<0> // too many bits, use generic version.
  1157. >::type
  1158. >::type
  1159. >::type
  1160. >::type tag_type;
  1161. BOOST_MATH_INSTRUMENT_CODE("tag_type = " << typeid(tag_type).name());
  1162. detail::erf_initializer<value_type, forwarding_policy, tag_type>::force_instantiate(); // Force constants to be initialized before main
  1163. return policies::checked_narrowing_cast<result_type, forwarding_policy>(detail::erf_imp(
  1164. static_cast<value_type>(z),
  1165. false,
  1166. forwarding_policy(),
  1167. tag_type()), "boost::math::erf<%1%>(%1%, %1%)");
  1168. }
  1169. template <class T, class Policy>
  1170. inline typename tools::promote_args<T>::type erfc(T z, const Policy& /* pol */)
  1171. {
  1172. typedef typename tools::promote_args<T>::type result_type;
  1173. typedef typename policies::evaluation<result_type, Policy>::type value_type;
  1174. typedef typename policies::precision<result_type, Policy>::type precision_type;
  1175. typedef typename policies::normalise<
  1176. Policy,
  1177. policies::promote_float<false>,
  1178. policies::promote_double<false>,
  1179. policies::discrete_quantile<>,
  1180. policies::assert_undefined<> >::type forwarding_policy;
  1181. BOOST_MATH_INSTRUMENT_CODE("result_type = " << typeid(result_type).name());
  1182. BOOST_MATH_INSTRUMENT_CODE("value_type = " << typeid(value_type).name());
  1183. BOOST_MATH_INSTRUMENT_CODE("precision_type = " << typeid(precision_type).name());
  1184. typedef typename mpl::if_<
  1185. mpl::less_equal<precision_type, mpl::int_<0> >,
  1186. mpl::int_<0>,
  1187. typename mpl::if_<
  1188. mpl::less_equal<precision_type, mpl::int_<53> >,
  1189. mpl::int_<53>, // double
  1190. typename mpl::if_<
  1191. mpl::less_equal<precision_type, mpl::int_<64> >,
  1192. mpl::int_<64>, // 80-bit long double
  1193. typename mpl::if_<
  1194. mpl::less_equal<precision_type, mpl::int_<113> >,
  1195. mpl::int_<113>, // 128-bit long double
  1196. mpl::int_<0> // too many bits, use generic version.
  1197. >::type
  1198. >::type
  1199. >::type
  1200. >::type tag_type;
  1201. BOOST_MATH_INSTRUMENT_CODE("tag_type = " << typeid(tag_type).name());
  1202. detail::erf_initializer<value_type, forwarding_policy, tag_type>::force_instantiate(); // Force constants to be initialized before main
  1203. return policies::checked_narrowing_cast<result_type, forwarding_policy>(detail::erf_imp(
  1204. static_cast<value_type>(z),
  1205. true,
  1206. forwarding_policy(),
  1207. tag_type()), "boost::math::erfc<%1%>(%1%, %1%)");
  1208. }
  1209. template <class T>
  1210. inline typename tools::promote_args<T>::type erf(T z)
  1211. {
  1212. return boost::math::erf(z, policies::policy<>());
  1213. }
  1214. template <class T>
  1215. inline typename tools::promote_args<T>::type erfc(T z)
  1216. {
  1217. return boost::math::erfc(z, policies::policy<>());
  1218. }
  1219. } // namespace math
  1220. } // namespace boost
  1221. #include <boost/math/special_functions/detail/erf_inv.hpp>
  1222. #endif // BOOST_MATH_SPECIAL_ERF_HPP