// Copyright (c) 2007, 2013 John Maddock // Copyright Christopher Kormanyos 2013. // Use, modification and distribution are subject to the // Boost Software License, Version 1.0. (See accompanying file // LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) // // This header just defines the function entry points, and adds dispatch // to the right implementation method. Most of the implementation details // are in separate headers and copyright Xiaogang Zhang. // #ifndef BOOST_MATH_BESSEL_HPP #define BOOST_MATH_BESSEL_HPP #ifdef _MSC_VER # pragma once #endif #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include namespace boost{ namespace math{ namespace detail{ template struct sph_bessel_j_small_z_series_term { typedef T result_type; sph_bessel_j_small_z_series_term(unsigned v_, T x) : N(0), v(v_) { BOOST_MATH_STD_USING mult = x / 2; if(v + 3 > max_factorial::value) { term = v * log(mult) - boost::math::lgamma(v+1+T(0.5f), Policy()); term = exp(term); } else term = pow(mult, T(v)) / boost::math::tgamma(v+1+T(0.5f), Policy()); mult *= -mult; } T operator()() { T r = term; ++N; term *= mult / (N * T(N + v + 0.5f)); return r; } private: unsigned N; unsigned v; T mult; T term; }; template inline T sph_bessel_j_small_z_series(unsigned v, T x, const Policy& pol) { BOOST_MATH_STD_USING // ADL of std names sph_bessel_j_small_z_series_term s(v, x); boost::uintmax_t max_iter = policies::get_max_series_iterations(); #if BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x582)) T zero = 0; T result = boost::math::tools::sum_series(s, boost::math::policies::get_epsilon(), max_iter, zero); #else T result = boost::math::tools::sum_series(s, boost::math::policies::get_epsilon(), max_iter); #endif policies::check_series_iterations("boost::math::sph_bessel_j_small_z_series<%1%>(%1%,%1%)", max_iter, pol); return result * sqrt(constants::pi() / 4); } template T cyl_bessel_j_imp(T v, T x, const bessel_no_int_tag& t, const Policy& pol) { BOOST_MATH_STD_USING static const char* function = "boost::math::bessel_j<%1%>(%1%,%1%)"; if(x < 0) { // better have integer v: if(floor(v) == v) { T r = cyl_bessel_j_imp(v, T(-x), t, pol); if(iround(v, pol) & 1) r = -r; return r; } else return policies::raise_domain_error( function, "Got x = %1%, but we need x >= 0", x, pol); } T j, y; bessel_jy(v, x, &j, &y, need_j, pol); return j; } template inline T cyl_bessel_j_imp(T v, T x, const bessel_maybe_int_tag&, const Policy& pol) { BOOST_MATH_STD_USING // ADL of std names. int ival = detail::iconv(v, pol); // If v is an integer, use the integer recursion // method, both that and Steeds method are O(v): if((0 == v - ival)) { return bessel_jn(ival, x, pol); } return cyl_bessel_j_imp(v, x, bessel_no_int_tag(), pol); } template inline T cyl_bessel_j_imp(int v, T x, const bessel_int_tag&, const Policy& pol) { BOOST_MATH_STD_USING return bessel_jn(v, x, pol); } template inline T sph_bessel_j_imp(unsigned n, T x, const Policy& pol) { BOOST_MATH_STD_USING // ADL of std names if(x < 0) return policies::raise_domain_error( "boost::math::sph_bessel_j<%1%>(%1%,%1%)", "Got x = %1%, but function requires x > 0.", x, pol); // // Special case, n == 0 resolves down to the sinus cardinal of x: // if(n == 0) return boost::math::sinc_pi(x, pol); // // Special case for x == 0: // if(x == 0) return 0; // // When x is small we may end up with 0/0, use series evaluation // instead, especially as it converges rapidly: // if(x < 1) return sph_bessel_j_small_z_series(n, x, pol); // // Default case is just a naive evaluation of the definition: // return sqrt(constants::pi() / (2 * x)) * cyl_bessel_j_imp(T(T(n)+T(0.5f)), x, bessel_no_int_tag(), pol); } template T cyl_bessel_i_imp(T v, T x, const Policy& pol) { // // This handles all the bessel I functions, note that we don't optimise // for integer v, other than the v = 0 or 1 special cases, as Millers // algorithm is at least as inefficient as the general case (the general // case has better error handling too). // BOOST_MATH_STD_USING if(x < 0) { // better have integer v: if(floor(v) == v) { T r = cyl_bessel_i_imp(v, T(-x), pol); if(iround(v, pol) & 1) r = -r; return r; } else return policies::raise_domain_error( "boost::math::cyl_bessel_i<%1%>(%1%,%1%)", "Got x = %1%, but we need x >= 0", x, pol); } if(x == 0) { return (v == 0) ? 1 : 0; } if(v == 0.5f) { // common special case, note try and avoid overflow in exp(x): if(x >= tools::log_max_value()) { T e = exp(x / 2); return e * (e / sqrt(2 * x * constants::pi())); } return sqrt(2 / (x * constants::pi())) * sinh(x); } if(policies::digits() <= 64) { if(v == 0) { return bessel_i0(x); } if(v == 1) { return bessel_i1(x); } } if((v > 0) && (x / v < 0.25)) return bessel_i_small_z_series(v, x, pol); T I, K; bessel_ik(v, x, &I, &K, need_i, pol); return I; } template inline T cyl_bessel_k_imp(T v, T x, const bessel_no_int_tag& /* t */, const Policy& pol) { static const char* function = "boost::math::cyl_bessel_k<%1%>(%1%,%1%)"; BOOST_MATH_STD_USING if(x < 0) { return policies::raise_domain_error( function, "Got x = %1%, but we need x > 0", x, pol); } if(x == 0) { return (v == 0) ? policies::raise_overflow_error(function, 0, pol) : policies::raise_domain_error( function, "Got x = %1%, but we need x > 0", x, pol); } T I, K; bessel_ik(v, x, &I, &K, need_k, pol); return K; } template inline T cyl_bessel_k_imp(T v, T x, const bessel_maybe_int_tag&, const Policy& pol) { BOOST_MATH_STD_USING if((floor(v) == v)) { return bessel_kn(itrunc(v), x, pol); } return cyl_bessel_k_imp(v, x, bessel_no_int_tag(), pol); } template inline T cyl_bessel_k_imp(int v, T x, const bessel_int_tag&, const Policy& pol) { return bessel_kn(v, x, pol); } template inline T cyl_neumann_imp(T v, T x, const bessel_no_int_tag&, const Policy& pol) { static const char* function = "boost::math::cyl_neumann<%1%>(%1%,%1%)"; BOOST_MATH_INSTRUMENT_VARIABLE(v); BOOST_MATH_INSTRUMENT_VARIABLE(x); if(x <= 0) { return (v == 0) && (x == 0) ? policies::raise_overflow_error(function, 0, pol) : policies::raise_domain_error( function, "Got x = %1%, but result is complex for x <= 0", x, pol); } T j, y; bessel_jy(v, x, &j, &y, need_y, pol); // // Post evaluation check for internal overflow during evaluation, // can occur when x is small and v is large, in which case the result // is -INF: // if(!(boost::math::isfinite)(y)) return -policies::raise_overflow_error(function, 0, pol); return y; } template inline T cyl_neumann_imp(T v, T x, const bessel_maybe_int_tag&, const Policy& pol) { BOOST_MATH_STD_USING BOOST_MATH_INSTRUMENT_VARIABLE(v); BOOST_MATH_INSTRUMENT_VARIABLE(x); if(floor(v) == v) { if(asymptotic_bessel_large_x_limit(v, x)) { T r = asymptotic_bessel_y_large_x_2(static_cast(abs(v)), x); if((v < 0) && (itrunc(v, pol) & 1)) r = -r; BOOST_MATH_INSTRUMENT_VARIABLE(r); return r; } else { T r = bessel_yn(itrunc(v, pol), x, pol); BOOST_MATH_INSTRUMENT_VARIABLE(r); return r; } } T r = cyl_neumann_imp(v, x, bessel_no_int_tag(), pol); BOOST_MATH_INSTRUMENT_VARIABLE(r); return r; } template inline T cyl_neumann_imp(int v, T x, const bessel_int_tag&, const Policy& pol) { BOOST_MATH_STD_USING BOOST_MATH_INSTRUMENT_VARIABLE(v); BOOST_MATH_INSTRUMENT_VARIABLE(x); if(asymptotic_bessel_large_x_limit(T(v), x)) { T r = asymptotic_bessel_y_large_x_2(static_cast(abs(v)), x); if((v < 0) && (v & 1)) r = -r; return r; } else return bessel_yn(v, x, pol); } template inline T sph_neumann_imp(unsigned v, T x, const Policy& pol) { BOOST_MATH_STD_USING // ADL of std names static const char* function = "boost::math::sph_neumann<%1%>(%1%,%1%)"; // // Nothing much to do here but check for errors, and // evaluate the function's definition directly: // if(x < 0) return policies::raise_domain_error( function, "Got x = %1%, but function requires x > 0.", x, pol); if(x < 2 * tools::min_value()) return -policies::raise_overflow_error(function, 0, pol); T result = cyl_neumann_imp(T(T(v)+0.5f), x, bessel_no_int_tag(), pol); T tx = sqrt(constants::pi() / (2 * x)); if((tx > 1) && (tools::max_value() / tx < result)) return -policies::raise_overflow_error(function, 0, pol); return result * tx; } template inline T cyl_bessel_j_zero_imp(T v, int m, const Policy& pol) { BOOST_MATH_STD_USING // ADL of std names, needed for floor. static const char* function = "boost::math::cyl_bessel_j_zero<%1%>(%1%, int)"; const T half_epsilon(boost::math::tools::epsilon() / 2U); // Handle non-finite order. if (!(boost::math::isfinite)(v) ) { return policies::raise_domain_error(function, "Order argument is %1%, but must be finite >= 0 !", v, pol); } // Handle negative rank. if(m < 0) { // Zeros of Jv(x) with negative rank are not defined and requesting one raises a domain error. return policies::raise_domain_error(function, "Requested the %1%'th zero, but the rank must be positive !", m, pol); } // Get the absolute value of the order. const bool order_is_negative = (v < 0); const T vv((!order_is_negative) ? v : T(-v)); // Check if the order is very close to zero or very close to an integer. const bool order_is_zero = (vv < half_epsilon); const bool order_is_integer = ((vv - floor(vv)) < half_epsilon); if(m == 0) { if(order_is_zero) { // The zero'th zero of J0(x) is not defined and requesting it raises a domain error. return policies::raise_domain_error(function, "Requested the %1%'th zero of J0, but the rank must be > 0 !", m, pol); } // The zero'th zero of Jv(x) for v < 0 is not defined // unless the order is a negative integer. if(order_is_negative && (!order_is_integer)) { // For non-integer, negative order, requesting the zero'th zero raises a domain error. return policies::raise_domain_error(function, "Requested the %1%'th zero of Jv for negative, non-integer order, but the rank must be > 0 !", m, pol); } // The zero'th zero does exist and its value is zero. return T(0); } // Set up the initial guess for the upcoming root-finding. // If the order is a negative integer, then use the corresponding // positive integer for the order. const T guess_root = boost::math::detail::bessel_zero::cyl_bessel_j_zero_detail::initial_guess((order_is_integer ? vv : v), m, pol); // Select the maximum allowed iterations from the policy. boost::uintmax_t number_of_iterations = policies::get_max_root_iterations(); const T delta_lo = ((guess_root > 0.2F) ? T(0.2) : T(guess_root / 2U)); // Perform the root-finding using Newton-Raphson iteration from Boost.Math. const T jvm = boost::math::tools::newton_raphson_iterate( boost::math::detail::bessel_zero::cyl_bessel_j_zero_detail::function_object_jv_and_jv_prime((order_is_integer ? vv : v), order_is_zero, pol), guess_root, T(guess_root - delta_lo), T(guess_root + 0.2F), policies::digits(), number_of_iterations); if(number_of_iterations >= policies::get_max_root_iterations()) { return policies::raise_evaluation_error(function, "Unable to locate root in a reasonable time:" " Current best guess is %1%", jvm, Policy()); } return jvm; } template inline T cyl_neumann_zero_imp(T v, int m, const Policy& pol) { BOOST_MATH_STD_USING // ADL of std names, needed for floor. static const char* function = "boost::math::cyl_neumann_zero<%1%>(%1%, int)"; // Handle non-finite order. if (!(boost::math::isfinite)(v) ) { return policies::raise_domain_error(function, "Order argument is %1%, but must be finite >= 0 !", v, pol); } // Handle negative rank. if(m < 0) { return policies::raise_domain_error(function, "Requested the %1%'th zero, but the rank must be positive !", m, pol); } const T half_epsilon(boost::math::tools::epsilon() / 2U); // Get the absolute value of the order. const bool order_is_negative = (v < 0); const T vv((!order_is_negative) ? v : T(-v)); const bool order_is_integer = ((vv - floor(vv)) < half_epsilon); // For negative integers, use reflection to positive integer order. if(order_is_negative && order_is_integer) return boost::math::detail::cyl_neumann_zero_imp(vv, m, pol); // Check if the order is very close to a negative half-integer. const T delta_half_integer(vv - (floor(vv) + 0.5F)); const bool order_is_negative_half_integer = (order_is_negative && ((delta_half_integer > -half_epsilon) && (delta_half_integer < +half_epsilon))); // The zero'th zero of Yv(x) for v < 0 is not defined // unless the order is a negative integer. if((m == 0) && (!order_is_negative_half_integer)) { // For non-integer, negative order, requesting the zero'th zero raises a domain error. return policies::raise_domain_error(function, "Requested the %1%'th zero of Yv for negative, non-half-integer order, but the rank must be > 0 !", m, pol); } // For negative half-integers, use the corresponding // spherical Bessel function of positive half-integer order. if(order_is_negative_half_integer) return boost::math::detail::cyl_bessel_j_zero_imp(vv, m, pol); // Set up the initial guess for the upcoming root-finding. // If the order is a negative integer, then use the corresponding // positive integer for the order. const T guess_root = boost::math::detail::bessel_zero::cyl_neumann_zero_detail::initial_guess(v, m, pol); // Select the maximum allowed iterations from the policy. boost::uintmax_t number_of_iterations = policies::get_max_root_iterations(); const T delta_lo = ((guess_root > 0.2F) ? T(0.2) : T(guess_root / 2U)); // Perform the root-finding using Newton-Raphson iteration from Boost.Math. const T yvm = boost::math::tools::newton_raphson_iterate( boost::math::detail::bessel_zero::cyl_neumann_zero_detail::function_object_yv_and_yv_prime(v, pol), guess_root, T(guess_root - delta_lo), T(guess_root + 0.2F), policies::digits(), number_of_iterations); if(number_of_iterations >= policies::get_max_root_iterations()) { return policies::raise_evaluation_error(function, "Unable to locate root in a reasonable time:" " Current best guess is %1%", yvm, Policy()); } return yvm; } } // namespace detail template inline typename detail::bessel_traits::result_type cyl_bessel_j(T1 v, T2 x, const Policy& /* pol */) { BOOST_FPU_EXCEPTION_GUARD typedef typename detail::bessel_traits::result_type result_type; typedef typename detail::bessel_traits::optimisation_tag tag_type; typedef typename policies::evaluation::type value_type; typedef typename policies::normalise< Policy, policies::promote_float, policies::promote_double, policies::discrete_quantile<>, policies::assert_undefined<> >::type forwarding_policy; return policies::checked_narrowing_cast(detail::cyl_bessel_j_imp(v, static_cast(x), tag_type(), forwarding_policy()), "boost::math::cyl_bessel_j<%1%>(%1%,%1%)"); } template inline typename detail::bessel_traits >::result_type cyl_bessel_j(T1 v, T2 x) { return cyl_bessel_j(v, x, policies::policy<>()); } template inline typename detail::bessel_traits::result_type sph_bessel(unsigned v, T x, const Policy& /* pol */) { BOOST_FPU_EXCEPTION_GUARD typedef typename detail::bessel_traits::result_type result_type; typedef typename policies::evaluation::type value_type; typedef typename policies::normalise< Policy, policies::promote_float, policies::promote_double, policies::discrete_quantile<>, policies::assert_undefined<> >::type forwarding_policy; return policies::checked_narrowing_cast(detail::sph_bessel_j_imp(v, static_cast(x), forwarding_policy()), "boost::math::sph_bessel<%1%>(%1%,%1%)"); } template inline typename detail::bessel_traits >::result_type sph_bessel(unsigned v, T x) { return sph_bessel(v, x, policies::policy<>()); } template inline typename detail::bessel_traits::result_type cyl_bessel_i(T1 v, T2 x, const Policy& /* pol */) { BOOST_FPU_EXCEPTION_GUARD typedef typename detail::bessel_traits::result_type result_type; typedef typename policies::evaluation::type value_type; typedef typename policies::normalise< Policy, policies::promote_float, policies::promote_double, policies::discrete_quantile<>, policies::assert_undefined<> >::type forwarding_policy; return policies::checked_narrowing_cast(detail::cyl_bessel_i_imp(v, static_cast(x), forwarding_policy()), "boost::math::cyl_bessel_i<%1%>(%1%,%1%)"); } template inline typename detail::bessel_traits >::result_type cyl_bessel_i(T1 v, T2 x) { return cyl_bessel_i(v, x, policies::policy<>()); } template inline typename detail::bessel_traits::result_type cyl_bessel_k(T1 v, T2 x, const Policy& /* pol */) { BOOST_FPU_EXCEPTION_GUARD typedef typename detail::bessel_traits::result_type result_type; typedef typename detail::bessel_traits::optimisation_tag tag_type; typedef typename policies::evaluation::type value_type; typedef typename policies::normalise< Policy, policies::promote_float, policies::promote_double, policies::discrete_quantile<>, policies::assert_undefined<> >::type forwarding_policy; return policies::checked_narrowing_cast(detail::cyl_bessel_k_imp(v, static_cast(x), tag_type(), forwarding_policy()), "boost::math::cyl_bessel_k<%1%>(%1%,%1%)"); } template inline typename detail::bessel_traits >::result_type cyl_bessel_k(T1 v, T2 x) { return cyl_bessel_k(v, x, policies::policy<>()); } template inline typename detail::bessel_traits::result_type cyl_neumann(T1 v, T2 x, const Policy& /* pol */) { BOOST_FPU_EXCEPTION_GUARD typedef typename detail::bessel_traits::result_type result_type; typedef typename detail::bessel_traits::optimisation_tag tag_type; typedef typename policies::evaluation::type value_type; typedef typename policies::normalise< Policy, policies::promote_float, policies::promote_double, policies::discrete_quantile<>, policies::assert_undefined<> >::type forwarding_policy; return policies::checked_narrowing_cast(detail::cyl_neumann_imp(v, static_cast(x), tag_type(), forwarding_policy()), "boost::math::cyl_neumann<%1%>(%1%,%1%)"); } template inline typename detail::bessel_traits >::result_type cyl_neumann(T1 v, T2 x) { return cyl_neumann(v, x, policies::policy<>()); } template inline typename detail::bessel_traits::result_type sph_neumann(unsigned v, T x, const Policy& /* pol */) { BOOST_FPU_EXCEPTION_GUARD typedef typename detail::bessel_traits::result_type result_type; typedef typename policies::evaluation::type value_type; typedef typename policies::normalise< Policy, policies::promote_float, policies::promote_double, policies::discrete_quantile<>, policies::assert_undefined<> >::type forwarding_policy; return policies::checked_narrowing_cast(detail::sph_neumann_imp(v, static_cast(x), forwarding_policy()), "boost::math::sph_neumann<%1%>(%1%,%1%)"); } template inline typename detail::bessel_traits >::result_type sph_neumann(unsigned v, T x) { return sph_neumann(v, x, policies::policy<>()); } template inline typename detail::bessel_traits::result_type cyl_bessel_j_zero(T v, int m, const Policy& /* pol */) { BOOST_FPU_EXCEPTION_GUARD typedef typename detail::bessel_traits::result_type result_type; typedef typename policies::evaluation::type value_type; typedef typename policies::normalise< Policy, policies::promote_float, policies::promote_double, policies::discrete_quantile<>, policies::assert_undefined<> >::type forwarding_policy; BOOST_STATIC_ASSERT_MSG( false == std::numeric_limits::is_specialized || ( true == std::numeric_limits::is_specialized && false == std::numeric_limits::is_integer), "Order must be a floating-point type."); return policies::checked_narrowing_cast(detail::cyl_bessel_j_zero_imp(v, m, forwarding_policy()), "boost::math::cyl_bessel_j_zero<%1%>(%1%,%1%)"); } template inline typename detail::bessel_traits >::result_type cyl_bessel_j_zero(T v, int m) { BOOST_STATIC_ASSERT_MSG( false == std::numeric_limits::is_specialized || ( true == std::numeric_limits::is_specialized && false == std::numeric_limits::is_integer), "Order must be a floating-point type."); return cyl_bessel_j_zero >(v, m, policies::policy<>()); } template inline OutputIterator cyl_bessel_j_zero(T v, int start_index, unsigned number_of_zeros, OutputIterator out_it, const Policy& pol) { BOOST_STATIC_ASSERT_MSG( false == std::numeric_limits::is_specialized || ( true == std::numeric_limits::is_specialized && false == std::numeric_limits::is_integer), "Order must be a floating-point type."); for(int i = 0; i < static_cast(number_of_zeros); ++i) { *out_it = boost::math::cyl_bessel_j_zero(v, start_index + i, pol); ++out_it; } return out_it; } template inline OutputIterator cyl_bessel_j_zero(T v, int start_index, unsigned number_of_zeros, OutputIterator out_it) { return cyl_bessel_j_zero(v, start_index, number_of_zeros, out_it, policies::policy<>()); } template inline typename detail::bessel_traits::result_type cyl_neumann_zero(T v, int m, const Policy& /* pol */) { BOOST_FPU_EXCEPTION_GUARD typedef typename detail::bessel_traits::result_type result_type; typedef typename policies::evaluation::type value_type; typedef typename policies::normalise< Policy, policies::promote_float, policies::promote_double, policies::discrete_quantile<>, policies::assert_undefined<> >::type forwarding_policy; BOOST_STATIC_ASSERT_MSG( false == std::numeric_limits::is_specialized || ( true == std::numeric_limits::is_specialized && false == std::numeric_limits::is_integer), "Order must be a floating-point type."); return policies::checked_narrowing_cast(detail::cyl_neumann_zero_imp(v, m, forwarding_policy()), "boost::math::cyl_neumann_zero<%1%>(%1%,%1%)"); } template inline typename detail::bessel_traits >::result_type cyl_neumann_zero(T v, int m) { BOOST_STATIC_ASSERT_MSG( false == std::numeric_limits::is_specialized || ( true == std::numeric_limits::is_specialized && false == std::numeric_limits::is_integer), "Order must be a floating-point type."); return cyl_neumann_zero >(v, m, policies::policy<>()); } template inline OutputIterator cyl_neumann_zero(T v, int start_index, unsigned number_of_zeros, OutputIterator out_it, const Policy& pol) { BOOST_STATIC_ASSERT_MSG( false == std::numeric_limits::is_specialized || ( true == std::numeric_limits::is_specialized && false == std::numeric_limits::is_integer), "Order must be a floating-point type."); for(int i = 0; i < static_cast(number_of_zeros); ++i) { *out_it = boost::math::cyl_neumann_zero(v, start_index + i, pol); ++out_it; } return out_it; } template inline OutputIterator cyl_neumann_zero(T v, int start_index, unsigned number_of_zeros, OutputIterator out_it) { return cyl_neumann_zero(v, start_index, number_of_zeros, out_it, policies::policy<>()); } } // namespace math } // namespace boost #endif // BOOST_MATH_BESSEL_HPP