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182 lines
6.8 KiB
182 lines
6.8 KiB
// 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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#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/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& pol) |
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{ |
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static const T P1[] = { |
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static_cast<T>(1.0723538782003176831e+11L), |
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static_cast<T>(-8.3716255451260504098e+09L), |
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static_cast<T>(2.0422274357376619816e+08L), |
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static_cast<T>(-2.1287548474401797963e+06L), |
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static_cast<T>(1.0102532948020907590e+04L), |
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static_cast<T>(-1.8402381979244993524e+01L), |
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}; |
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static const T Q1[] = { |
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static_cast<T>(5.8873865738997033405e+11L), |
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static_cast<T>(8.1617187777290363573e+09L), |
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static_cast<T>(5.5662956624278251596e+07L), |
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static_cast<T>(2.3889393209447253406e+05L), |
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static_cast<T>(6.6475986689240190091e+02L), |
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static_cast<T>(1.0L), |
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}; |
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static const T P2[] = { |
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static_cast<T>(-2.2213976967566192242e+13L), |
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static_cast<T>(-5.5107435206722644429e+11L), |
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static_cast<T>(4.3600098638603061642e+10L), |
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static_cast<T>(-6.9590439394619619534e+08L), |
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static_cast<T>(4.6905288611678631510e+06L), |
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static_cast<T>(-1.4566865832663635920e+04L), |
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static_cast<T>(1.7427031242901594547e+01L), |
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}; |
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static const T Q2[] = { |
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static_cast<T>(4.3386146580707264428e+14L), |
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static_cast<T>(5.4266824419412347550e+12L), |
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static_cast<T>(3.4015103849971240096e+10L), |
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static_cast<T>(1.3960202770986831075e+08L), |
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static_cast<T>(4.0669982352539552018e+05L), |
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static_cast<T>(8.3030857612070288823e+02L), |
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static_cast<T>(1.0L), |
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}; |
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static const T P3[] = { |
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static_cast<T>(-8.0728726905150210443e+15L), |
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static_cast<T>(6.7016641869173237784e+14L), |
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static_cast<T>(-1.2829912364088687306e+11L), |
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static_cast<T>(-1.9363051266772083678e+11L), |
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static_cast<T>(2.1958827170518100757e+09L), |
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static_cast<T>(-1.0085539923498211426e+07L), |
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static_cast<T>(2.1363534169313901632e+04L), |
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static_cast<T>(-1.7439661319197499338e+01L), |
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}; |
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static const T Q3[] = { |
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static_cast<T>(3.4563724628846457519e+17L), |
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static_cast<T>(3.9272425569640309819e+15L), |
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static_cast<T>(2.2598377924042897629e+13L), |
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static_cast<T>(8.6926121104209825246e+10L), |
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static_cast<T>(2.4727219475672302327e+08L), |
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static_cast<T>(5.3924739209768057030e+05L), |
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static_cast<T>(8.7903362168128450017e+02L), |
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static_cast<T>(1.0L), |
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}; |
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static const T PC[] = { |
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static_cast<T>(2.2779090197304684302e+04L), |
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static_cast<T>(4.1345386639580765797e+04L), |
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static_cast<T>(2.1170523380864944322e+04L), |
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static_cast<T>(3.4806486443249270347e+03L), |
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static_cast<T>(1.5376201909008354296e+02L), |
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static_cast<T>(8.8961548424210455236e-01L), |
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}; |
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static const T QC[] = { |
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static_cast<T>(2.2779090197304684318e+04L), |
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static_cast<T>(4.1370412495510416640e+04L), |
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static_cast<T>(2.1215350561880115730e+04L), |
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static_cast<T>(3.5028735138235608207e+03L), |
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static_cast<T>(1.5711159858080893649e+02L), |
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static_cast<T>(1.0L), |
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}; |
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static const T PS[] = { |
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static_cast<T>(-8.9226600200800094098e+01L), |
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static_cast<T>(-1.8591953644342993800e+02L), |
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static_cast<T>(-1.1183429920482737611e+02L), |
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static_cast<T>(-2.2300261666214198472e+01L), |
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static_cast<T>(-1.2441026745835638459e+00L), |
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static_cast<T>(-8.8033303048680751817e-03L), |
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}; |
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static const T QS[] = { |
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static_cast<T>(5.7105024128512061905e+03L), |
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static_cast<T>(1.1951131543434613647e+04L), |
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static_cast<T>(7.2642780169211018836e+03L), |
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static_cast<T>(1.4887231232283756582e+03L), |
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static_cast<T>(9.0593769594993125859e+01L), |
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static_cast<T>(1.0L), |
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}; |
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static const T x1 = static_cast<T>(8.9357696627916752158e-01L), |
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x2 = static_cast<T>(3.9576784193148578684e+00L), |
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x3 = static_cast<T>(7.0860510603017726976e+00L), |
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x11 = static_cast<T>(2.280e+02L), |
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x12 = static_cast<T>(2.9519662791675215849e-03L), |
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x21 = static_cast<T>(1.0130e+03L), |
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x22 = static_cast<T>(6.4716931485786837568e-04L), |
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x31 = static_cast<T>(1.8140e+03L), |
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x32 = static_cast<T>(1.1356030177269762362e-04L) |
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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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T z = x - 0.25f * pi<T>(); |
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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 = sqrt(2 / (x * pi<T>())); |
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value = factor * (rc * sin(z) + y * rs * cos(z)); |
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} |
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return value; |
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} |
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}}} // namespaces |
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#endif // BOOST_MATH_BESSEL_Y0_HPP |
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