bessel_y1.hpp 9.2 KB

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  1. // Copyright (c) 2006 Xiaogang Zhang
  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_BESSEL_Y1_HPP
  6. #define BOOST_MATH_BESSEL_Y1_HPP
  7. #ifdef _MSC_VER
  8. #pragma once
  9. #pragma warning(push)
  10. #pragma warning(disable:4702) // Unreachable code (release mode only warning)
  11. #endif
  12. #include <boost/math/special_functions/detail/bessel_j1.hpp>
  13. #include <boost/math/constants/constants.hpp>
  14. #include <boost/math/tools/rational.hpp>
  15. #include <boost/math/tools/big_constant.hpp>
  16. #include <boost/math/policies/error_handling.hpp>
  17. #include <boost/assert.hpp>
  18. #if defined(__GNUC__) && defined(BOOST_MATH_USE_FLOAT128)
  19. //
  20. // This is the only way we can avoid
  21. // warning: non-standard suffix on floating constant [-Wpedantic]
  22. // when building with -Wall -pedantic. Neither __extension__
  23. // nor #pragma dianostic ignored work :(
  24. //
  25. #pragma GCC system_header
  26. #endif
  27. // Bessel function of the second kind of order one
  28. // x <= 8, minimax rational approximations on root-bracketing intervals
  29. // x > 8, Hankel asymptotic expansion in Hart, Computer Approximations, 1968
  30. namespace boost { namespace math { namespace detail{
  31. template <typename T, typename Policy>
  32. T bessel_y1(T x, const Policy&);
  33. template <class T, class Policy>
  34. struct bessel_y1_initializer
  35. {
  36. struct init
  37. {
  38. init()
  39. {
  40. do_init();
  41. }
  42. static void do_init()
  43. {
  44. bessel_y1(T(1), Policy());
  45. }
  46. void force_instantiate()const{}
  47. };
  48. static const init initializer;
  49. static void force_instantiate()
  50. {
  51. initializer.force_instantiate();
  52. }
  53. };
  54. template <class T, class Policy>
  55. const typename bessel_y1_initializer<T, Policy>::init bessel_y1_initializer<T, Policy>::initializer;
  56. template <typename T, typename Policy>
  57. T bessel_y1(T x, const Policy& pol)
  58. {
  59. bessel_y1_initializer<T, Policy>::force_instantiate();
  60. static const T P1[] = {
  61. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 4.0535726612579544093e+13)),
  62. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 5.4708611716525426053e+12)),
  63. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, -3.7595974497819597599e+11)),
  64. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 7.2144548214502560419e+09)),
  65. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, -5.9157479997408395984e+07)),
  66. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 2.2157953222280260820e+05)),
  67. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, -3.1714424660046133456e+02)),
  68. };
  69. static const T Q1[] = {
  70. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 3.0737873921079286084e+14)),
  71. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 4.1272286200406461981e+12)),
  72. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 2.7800352738690585613e+10)),
  73. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 1.2250435122182963220e+08)),
  74. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 3.8136470753052572164e+05)),
  75. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 8.2079908168393867438e+02)),
  76. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 1.0)),
  77. };
  78. static const T P2[] = {
  79. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 1.1514276357909013326e+19)),
  80. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, -5.6808094574724204577e+18)),
  81. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, -2.3638408497043134724e+16)),
  82. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 4.0686275289804744814e+15)),
  83. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, -5.9530713129741981618e+13)),
  84. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 3.7453673962438488783e+11)),
  85. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, -1.1957961912070617006e+09)),
  86. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 1.9153806858264202986e+06)),
  87. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, -1.2337180442012953128e+03)),
  88. };
  89. static const T Q2[] = {
  90. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 5.3321844313316185697e+20)),
  91. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 5.6968198822857178911e+18)),
  92. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 3.0837179548112881950e+16)),
  93. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 1.1187010065856971027e+14)),
  94. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 3.0221766852960403645e+11)),
  95. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 6.3550318087088919566e+08)),
  96. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 1.0453748201934079734e+06)),
  97. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 1.2855164849321609336e+03)),
  98. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 1.0)),
  99. };
  100. static const T PC[] = {
  101. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, -4.4357578167941278571e+06)),
  102. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, -9.9422465050776411957e+06)),
  103. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, -6.6033732483649391093e+06)),
  104. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, -1.5235293511811373833e+06)),
  105. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, -1.0982405543459346727e+05)),
  106. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, -1.6116166443246101165e+03)),
  107. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 0.0)),
  108. };
  109. static const T QC[] = {
  110. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, -4.4357578167941278568e+06)),
  111. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, -9.9341243899345856590e+06)),
  112. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, -6.5853394797230870728e+06)),
  113. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, -1.5118095066341608816e+06)),
  114. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, -1.0726385991103820119e+05)),
  115. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, -1.4550094401904961825e+03)),
  116. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 1.0)),
  117. };
  118. static const T PS[] = {
  119. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 3.3220913409857223519e+04)),
  120. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 8.5145160675335701966e+04)),
  121. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 6.6178836581270835179e+04)),
  122. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 1.8494262873223866797e+04)),
  123. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 1.7063754290207680021e+03)),
  124. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 3.5265133846636032186e+01)),
  125. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 0.0)),
  126. };
  127. static const T QS[] = {
  128. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 7.0871281941028743574e+05)),
  129. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 1.8194580422439972989e+06)),
  130. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 1.4194606696037208929e+06)),
  131. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 4.0029443582266975117e+05)),
  132. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 3.7890229745772202641e+04)),
  133. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 8.6383677696049909675e+02)),
  134. static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 1.0)),
  135. };
  136. static const T x1 = static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 2.1971413260310170351e+00)),
  137. x2 = static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 5.4296810407941351328e+00)),
  138. x11 = static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 5.620e+02)),
  139. x12 = static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 1.8288260310170351490e-03)),
  140. x21 = static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 1.3900e+03)),
  141. x22 = static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, -6.4592058648672279948e-06))
  142. ;
  143. T value, factor, r, rc, rs;
  144. BOOST_MATH_STD_USING
  145. using namespace boost::math::tools;
  146. using namespace boost::math::constants;
  147. if (x <= 0)
  148. {
  149. return policies::raise_domain_error<T>("bost::math::bessel_y1<%1%>(%1%,%1%)",
  150. "Got x == %1%, but x must be > 0, complex result not supported.", x, pol);
  151. }
  152. if (x <= 4) // x in (0, 4]
  153. {
  154. T y = x * x;
  155. T z = 2 * log(x/x1) * bessel_j1(x) / pi<T>();
  156. r = evaluate_rational(P1, Q1, y);
  157. factor = (x + x1) * ((x - x11/256) - x12) / x;
  158. value = z + factor * r;
  159. }
  160. else if (x <= 8) // x in (4, 8]
  161. {
  162. T y = x * x;
  163. T z = 2 * log(x/x2) * bessel_j1(x) / pi<T>();
  164. r = evaluate_rational(P2, Q2, y);
  165. factor = (x + x2) * ((x - x21/256) - x22) / x;
  166. value = z + factor * r;
  167. }
  168. else // x in (8, \infty)
  169. {
  170. T y = 8 / x;
  171. T y2 = y * y;
  172. rc = evaluate_rational(PC, QC, y2);
  173. rs = evaluate_rational(PS, QS, y2);
  174. factor = 1 / (sqrt(x) * root_pi<T>());
  175. //
  176. // This code is really just:
  177. //
  178. // T z = x - 0.75f * pi<T>();
  179. // value = factor * (rc * sin(z) + y * rs * cos(z));
  180. //
  181. // But using the sin/cos addition rules, plus constants for sin/cos of 3PI/4
  182. // which then cancel out with corresponding terms in "factor".
  183. //
  184. T sx = sin(x);
  185. T cx = cos(x);
  186. value = factor * (y * rs * (sx - cx) - rc * (sx + cx));
  187. }
  188. return value;
  189. }
  190. }}} // namespaces
  191. #ifdef _MSC_VER
  192. #pragma warning(pop)
  193. #endif
  194. #endif // BOOST_MATH_BESSEL_Y1_HPP