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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 | ||
6 | #ifndef BOOST_MATH_BESSEL_K1_HPP | |
7 | #define BOOST_MATH_BESSEL_K1_HPP | |
8 | ||
9 | #ifdef _MSC_VER | |
10 | #pragma once | |
11 | #pragma warning(push) | |
12 | #pragma warning(disable:4702) // Unreachable code (release mode only warning) | |
13 | #endif | |
14 | ||
15 | #include <boost/math/tools/rational.hpp> | |
16 | #include <boost/math/tools/big_constant.hpp> | |
17 | #include <boost/math/policies/error_handling.hpp> | |
18 | #include <boost/assert.hpp> | |
19 | ||
20 | // Modified Bessel function of the second kind of order one | |
21 | // minimax rational approximations on intervals, see | |
22 | // Russon and Blair, Chalk River Report AECL-3461, 1969 | |
23 | ||
24 | namespace boost { namespace math { namespace detail{ | |
25 | ||
26 | template <typename T, typename Policy> | |
27 | T bessel_k1(T x, const Policy&); | |
28 | ||
29 | template <class T, class Policy> | |
30 | struct bessel_k1_initializer | |
31 | { | |
32 | struct init | |
33 | { | |
34 | init() | |
35 | { | |
36 | do_init(); | |
37 | } | |
38 | static void do_init() | |
39 | { | |
40 | bessel_k1(T(1), Policy()); | |
41 | } | |
42 | void force_instantiate()const{} | |
43 | }; | |
44 | static const init initializer; | |
45 | static void force_instantiate() | |
46 | { | |
47 | initializer.force_instantiate(); | |
48 | } | |
49 | }; | |
50 | ||
51 | template <class T, class Policy> | |
52 | const typename bessel_k1_initializer<T, Policy>::init bessel_k1_initializer<T, Policy>::initializer; | |
53 | ||
54 | template <typename T, typename Policy> | |
55 | T bessel_k1(T x, const Policy& pol) | |
56 | { | |
57 | bessel_k1_initializer<T, Policy>::force_instantiate(); | |
58 | ||
59 | static const T P1[] = { | |
60 | static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, -2.2149374878243304548e+06)), | |
61 | static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 7.1938920065420586101e+05)), | |
62 | static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 1.7733324035147015630e+05)), | |
63 | static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 7.1885382604084798576e+03)), | |
64 | static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 9.9991373567429309922e+01)), | |
65 | static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 4.8127070456878442310e-01)) | |
66 | }; | |
67 | static const T Q1[] = { | |
68 | static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, -2.2149374878243304548e+06)), | |
69 | static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 3.7264298672067697862e+04)), | |
70 | static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, -2.8143915754538725829e+02)), | |
71 | static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 1.0)) | |
72 | }; | |
73 | static const T P2[] = { | |
74 | static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 0.0)), | |
75 | static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, -1.3531161492785421328e+06)), | |
76 | static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, -1.4758069205414222471e+05)), | |
77 | static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, -4.5051623763436087023e+03)), | |
78 | static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, -5.3103913335180275253e+01)), | |
79 | static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, -2.2795590826955002390e-01)) | |
80 | }; | |
81 | static const T Q2[] = { | |
82 | static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, -2.7062322985570842656e+06)), | |
83 | static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 4.3117653211351080007e+04)), | |
84 | static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, -3.0507151578787595807e+02)), | |
85 | static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 1.0)) | |
86 | }; | |
87 | static const T P3[] = { | |
88 | static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 2.2196792496874548962e+00)), | |
89 | static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 4.4137176114230414036e+01)), | |
90 | static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 3.4122953486801312910e+02)), | |
91 | static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 1.3319486433183221990e+03)), | |
92 | static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 2.8590657697910288226e+03)), | |
93 | static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 3.4540675585544584407e+03)), | |
94 | static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 2.3123742209168871550e+03)), | |
95 | static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 8.1094256146537402173e+02)), | |
96 | static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 1.3182609918569941308e+02)), | |
97 | static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 7.5584584631176030810e+00)), | |
98 | static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 6.4257745859173138767e-02)) | |
99 | }; | |
100 | static const T Q3[] = { | |
101 | static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 1.7710478032601086579e+00)), | |
102 | static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 3.4552228452758912848e+01)), | |
103 | static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 2.5951223655579051357e+02)), | |
104 | static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 9.6929165726802648634e+02)), | |
105 | static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 1.9448440788918006154e+03)), | |
106 | static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 2.1181000487171943810e+03)), | |
107 | static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 1.2082692316002348638e+03)), | |
108 | static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 3.3031020088765390854e+02)), | |
109 | static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 3.6001069306861518855e+01)), | |
110 | static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 1.0)) | |
111 | }; | |
112 | T value, factor, r, r1, r2; | |
113 | ||
114 | BOOST_MATH_STD_USING | |
115 | using namespace boost::math::tools; | |
116 | ||
117 | static const char* function = "boost::math::bessel_k1<%1%>(%1%,%1%)"; | |
118 | ||
119 | if (x < 0) | |
120 | { | |
121 | return policies::raise_domain_error<T>(function, | |
122 | "Got x = %1%, but argument x must be non-negative, complex number result not supported.", x, pol); | |
123 | } | |
124 | if (x == 0) | |
125 | { | |
126 | return policies::raise_overflow_error<T>(function, 0, pol); | |
127 | } | |
128 | if (x <= 1) // x in (0, 1] | |
129 | { | |
130 | T y = x * x; | |
131 | r1 = evaluate_polynomial(P1, y) / evaluate_polynomial(Q1, y); | |
132 | r2 = evaluate_polynomial(P2, y) / evaluate_polynomial(Q2, y); | |
133 | factor = log(x); | |
134 | value = (r1 + factor * r2) / x; | |
135 | } | |
136 | else // x in (1, \infty) | |
137 | { | |
138 | T y = 1 / x; | |
139 | r = evaluate_polynomial(P3, y) / evaluate_polynomial(Q3, y); | |
140 | factor = exp(-x) / sqrt(x); | |
141 | value = factor * r; | |
142 | } | |
143 | ||
144 | return value; | |
145 | } | |
146 | ||
147 | }}} // namespaces | |
148 | ||
149 | #ifdef _MSC_VER | |
150 | #pragma warning(pop) | |
151 | #endif | |
152 | ||
153 | #endif // BOOST_MATH_BESSEL_K1_HPP | |
154 |