/usr/include/boost/math/special_functions
Edit: /usr/include/boost/math/special_functions/laguerre.hpp (3651B)
// (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{
// Recurrence 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 recurrence:
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 boost::true_type&)
{
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 boost::false_type&)
{
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