X-Git-Url: https://git.donarmstrong.com/?p=rsem.git;a=blobdiff_plain;f=boost%2Fmath%2Fspecial_functions%2Flaguerre.hpp;fp=boost%2Fmath%2Fspecial_functions%2Flaguerre.hpp;h=070927f26bc66d9fb87e1ab0e3e629cb1ba5e924;hp=0000000000000000000000000000000000000000;hb=2d71eb92104693ca9baa5a2e1c23eeca776d8fd3;hpb=da57529b92adbb7ae74a89861cb39fb35ac7c62d diff --git a/boost/math/special_functions/laguerre.hpp b/boost/math/special_functions/laguerre.hpp new file mode 100644 index 0000000..070927f --- /dev/null +++ b/boost/math/special_functions/laguerre.hpp @@ -0,0 +1,139 @@ + +// (C) Copyright John Maddock 2006. +// 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) + +#ifndef BOOST_MATH_SPECIAL_LAGUERRE_HPP +#define BOOST_MATH_SPECIAL_LAGUERRE_HPP + +#ifdef _MSC_VER +#pragma once +#endif + +#include +#include +#include + +namespace boost{ +namespace math{ + +// Recurrance relation for Laguerre polynomials: +template +inline typename tools::promote_args::type + laguerre_next(unsigned n, T1 x, T2 Ln, T3 Lnm1) +{ + typedef typename tools::promote_args::type result_type; + return ((2 * n + 1 - result_type(x)) * result_type(Ln) - n * result_type(Lnm1)) / (n + 1); +} + +namespace detail{ + +// Implement Laguerre polynomials via recurrance: +template +T laguerre_imp(unsigned n, T x) +{ + T p0 = 1; + T p1 = 1 - x; + + if(n == 0) + return p0; + + unsigned c = 1; + + while(c < n) + { + std::swap(p0, p1); + p1 = laguerre_next(c, x, p0, p1); + ++c; + } + return p1; +} + +template +inline typename tools::promote_args::type +laguerre(unsigned n, T x, const Policy&, const mpl::true_&) +{ + typedef typename tools::promote_args::type result_type; + typedef typename policies::evaluation::type value_type; + return policies::checked_narrowing_cast(detail::laguerre_imp(n, static_cast(x)), "boost::math::laguerre<%1%>(unsigned, %1%)"); +} + +template +inline typename tools::promote_args::type + laguerre(unsigned n, unsigned m, T x, const mpl::false_&) +{ + return boost::math::laguerre(n, m, x, policies::policy<>()); +} + +} // namespace detail + +template +inline typename tools::promote_args::type + laguerre(unsigned n, T x) +{ + return laguerre(n, x, policies::policy<>()); +} + +// Recurrence for associated polynomials: +template +inline typename tools::promote_args::type + laguerre_next(unsigned n, unsigned l, T1 x, T2 Pl, T3 Plm1) +{ + typedef typename tools::promote_args::type result_type; + return ((2 * n + l + 1 - result_type(x)) * result_type(Pl) - (n + l) * result_type(Plm1)) / (n+1); +} + +namespace detail{ +// Laguerre Associated Polynomial: +template +T laguerre_imp(unsigned n, unsigned m, T x, const Policy& pol) +{ + // Special cases: + if(m == 0) + return boost::math::laguerre(n, x, pol); + + T p0 = 1; + + if(n == 0) + return p0; + + T p1 = m + 1 - x; + + unsigned c = 1; + + while(c < n) + { + std::swap(p0, p1); + p1 = laguerre_next(c, m, x, p0, p1); + ++c; + } + return p1; +} + +} + +template +inline typename tools::promote_args::type + laguerre(unsigned n, unsigned m, T x, const Policy& pol) +{ + typedef typename tools::promote_args::type result_type; + typedef typename policies::evaluation::type value_type; + return policies::checked_narrowing_cast(detail::laguerre_imp(n, m, static_cast(x), pol), "boost::math::laguerre<%1%>(unsigned, unsigned, %1%)"); +} + +template +inline typename laguerre_result::type + laguerre(unsigned n, T1 m, T2 x) +{ + typedef typename policies::is_policy::type tag_type; + return detail::laguerre(n, m, x, tag_type()); +} + +} // namespace math +} // namespace boost + +#endif // BOOST_MATH_SPECIAL_LAGUERRE_HPP + + +