231 lines
10 KiB
Plaintext
231 lines
10 KiB
Plaintext
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// Copyright (c) 2006 Xiaogang Zhang
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// Use, modification and distribution are subject to the
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// Boost Software License, Version 1.0. (See accompanying file
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// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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#ifndef BOOST_MATH_BESSEL_Y0_HPP
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#define BOOST_MATH_BESSEL_Y0_HPP
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#ifdef _MSC_VER
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#pragma once
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#pragma warning(push)
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#pragma warning(disable:4702) // Unreachable code (release mode only warning)
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#endif
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#include <boost/math/special_functions/detail/bessel_j0.hpp>
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#include <boost/math/constants/constants.hpp>
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#include <boost/math/tools/rational.hpp>
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#include <boost/math/tools/big_constant.hpp>
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#include <boost/math/policies/error_handling.hpp>
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#include <boost/assert.hpp>
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// Bessel function of the second kind of order zero
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// x <= 8, minimax rational approximations on root-bracketing intervals
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// x > 8, Hankel asymptotic expansion in Hart, Computer Approximations, 1968
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namespace boost { namespace math { namespace detail{
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template <typename T, typename Policy>
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T bessel_y0(T x, const Policy&);
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template <class T, class Policy>
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struct bessel_y0_initializer
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{
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struct init
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{
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init()
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{
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do_init();
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}
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static void do_init()
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{
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bessel_y0(T(1), Policy());
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}
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void force_instantiate()const{}
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};
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static const init initializer;
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static void force_instantiate()
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{
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initializer.force_instantiate();
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}
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};
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template <class T, class Policy>
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const typename bessel_y0_initializer<T, Policy>::init bessel_y0_initializer<T, Policy>::initializer;
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template <typename T, typename Policy>
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T bessel_y0(T x, const Policy& pol)
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{
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bessel_y0_initializer<T, Policy>::force_instantiate();
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static const T P1[] = {
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 1.0723538782003176831e+11)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, -8.3716255451260504098e+09)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 2.0422274357376619816e+08)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, -2.1287548474401797963e+06)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 1.0102532948020907590e+04)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, -1.8402381979244993524e+01)),
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};
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static const T Q1[] = {
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 5.8873865738997033405e+11)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 8.1617187777290363573e+09)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 5.5662956624278251596e+07)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 2.3889393209447253406e+05)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 6.6475986689240190091e+02)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 1.0)),
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};
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static const T P2[] = {
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, -2.2213976967566192242e+13)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, -5.5107435206722644429e+11)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 4.3600098638603061642e+10)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, -6.9590439394619619534e+08)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 4.6905288611678631510e+06)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, -1.4566865832663635920e+04)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 1.7427031242901594547e+01)),
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};
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static const T Q2[] = {
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 4.3386146580707264428e+14)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 5.4266824419412347550e+12)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 3.4015103849971240096e+10)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 1.3960202770986831075e+08)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 4.0669982352539552018e+05)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 8.3030857612070288823e+02)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 1.0)),
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};
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static const T P3[] = {
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, -8.0728726905150210443e+15)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 6.7016641869173237784e+14)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, -1.2829912364088687306e+11)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, -1.9363051266772083678e+11)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 2.1958827170518100757e+09)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, -1.0085539923498211426e+07)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 2.1363534169313901632e+04)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, -1.7439661319197499338e+01)),
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};
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static const T Q3[] = {
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 3.4563724628846457519e+17)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 3.9272425569640309819e+15)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 2.2598377924042897629e+13)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 8.6926121104209825246e+10)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 2.4727219475672302327e+08)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 5.3924739209768057030e+05)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 8.7903362168128450017e+02)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 1.0)),
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};
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static const T PC[] = {
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 2.2779090197304684302e+04)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 4.1345386639580765797e+04)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 2.1170523380864944322e+04)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 3.4806486443249270347e+03)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 1.5376201909008354296e+02)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 8.8961548424210455236e-01)),
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};
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static const T QC[] = {
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 2.2779090197304684318e+04)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 4.1370412495510416640e+04)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 2.1215350561880115730e+04)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 3.5028735138235608207e+03)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 1.5711159858080893649e+02)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 1.0)),
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};
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static const T PS[] = {
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, -8.9226600200800094098e+01)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, -1.8591953644342993800e+02)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, -1.1183429920482737611e+02)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, -2.2300261666214198472e+01)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, -1.2441026745835638459e+00)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, -8.8033303048680751817e-03)),
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};
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static const T QS[] = {
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 5.7105024128512061905e+03)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 1.1951131543434613647e+04)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 7.2642780169211018836e+03)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 1.4887231232283756582e+03)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 9.0593769594993125859e+01)),
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static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 1.0)),
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};
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static const T x1 = static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 8.9357696627916752158e-01)),
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x2 = static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 3.9576784193148578684e+00)),
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x3 = static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 7.0860510603017726976e+00)),
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x11 = static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 2.280e+02)),
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x12 = static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 2.9519662791675215849e-03)),
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x21 = static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 1.0130e+03)),
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x22 = static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 6.4716931485786837568e-04)),
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x31 = static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 1.8140e+03)),
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x32 = static_cast<T>(BOOST_MATH_BIG_CONSTANT(T, 64, 1.1356030177269762362e-04))
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;
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T value, factor, r, rc, rs;
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BOOST_MATH_STD_USING
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using namespace boost::math::tools;
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using namespace boost::math::constants;
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static const char* function = "boost::math::bessel_y0<%1%>(%1%,%1%)";
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if (x < 0)
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{
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return policies::raise_domain_error<T>(function,
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"Got x = %1% but x must be non-negative, complex result not supported.", x, pol);
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}
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if (x == 0)
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{
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return -policies::raise_overflow_error<T>(function, 0, pol);
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}
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if (x <= 3) // x in (0, 3]
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{
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T y = x * x;
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T z = 2 * log(x/x1) * bessel_j0(x) / pi<T>();
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r = evaluate_rational(P1, Q1, y);
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factor = (x + x1) * ((x - x11/256) - x12);
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value = z + factor * r;
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}
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else if (x <= 5.5f) // x in (3, 5.5]
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{
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T y = x * x;
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T z = 2 * log(x/x2) * bessel_j0(x) / pi<T>();
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r = evaluate_rational(P2, Q2, y);
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factor = (x + x2) * ((x - x21/256) - x22);
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value = z + factor * r;
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}
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else if (x <= 8) // x in (5.5, 8]
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{
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T y = x * x;
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T z = 2 * log(x/x3) * bessel_j0(x) / pi<T>();
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r = evaluate_rational(P3, Q3, y);
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factor = (x + x3) * ((x - x31/256) - x32);
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value = z + factor * r;
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}
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else // x in (8, \infty)
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{
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T y = 8 / x;
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T y2 = y * y;
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rc = evaluate_rational(PC, QC, y2);
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rs = evaluate_rational(PS, QS, y2);
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factor = constants::one_div_root_pi<T>() / sqrt(x);
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//
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// The following code is really just:
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//
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// T z = x - 0.25f * pi<T>();
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// value = factor * (rc * sin(z) + y * rs * cos(z));
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//
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// But using the sin/cos addition formulae and constant values for
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// sin/cos of PI/4 which then cancel part of the "factor" term as they're all
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// 1 / sqrt(2):
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//
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T sx = sin(x);
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T cx = cos(x);
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value = factor * (rc * (sx - cx) + y * rs * (cx + sx));
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}
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return value;
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}
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}}} // namespaces
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#ifdef _MSC_VER
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#pragma warning(pop)
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#endif
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#endif // BOOST_MATH_BESSEL_Y0_HPP
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