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1 2///////////////////////////////////////////////////////////////////////////////3// Copyright 2013 Nikhar Agrawal4// Copyright 2013 Christopher Kormanyos5// Copyright 2014 John Maddock6// Copyright 2013 Paul Bristow7// Distributed under the Boost8// Software License, Version 1.0. (See accompanying file9// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)10 11#ifndef _BOOST_POLYGAMMA_2013_07_30_HPP_12 #define _BOOST_POLYGAMMA_2013_07_30_HPP_13 14#include <boost/math/special_functions/factorials.hpp>15#include <boost/math/special_functions/detail/polygamma.hpp>16#include <boost/math/special_functions/trigamma.hpp>17 18namespace boost { namespace math {19 20 21 template<class T, class Policy>22 inline typename tools::promote_args<T>::type polygamma(const int n, T x, const Policy& pol)23 {24 //25 // Filter off special cases right at the start:26 //27 if(n == 0)28 return boost::math::digamma(x, pol);29 if(n == 1)30 return boost::math::trigamma(x, pol);31 //32 // We've found some standard library functions to misbehave if any FPU exception flags33 // are set prior to their call, this code will clear those flags, then reset them34 // on exit:35 //36 BOOST_FPU_EXCEPTION_GUARD37 //38 // The type of the result - the common type of T and U after39 // any integer types have been promoted to double:40 //41 typedef typename tools::promote_args<T>::type result_type;42 //43 // The type used for the calculation. This may be a wider type than44 // the result in order to ensure full precision:45 //46 typedef typename policies::evaluation<result_type, Policy>::type value_type;47 //48 // The type of the policy to forward to the actual implementation.49 // We disable promotion of float and double as that's [possibly]50 // happened already in the line above. Also reset to the default51 // any policies we don't use (reduces code bloat if we're called52 // multiple times with differing policies we don't actually use).53 // Also normalise the type, again to reduce code bloat in case we're54 // called multiple times with functionally identical policies that happen55 // to be different types.56 //57 typedef typename policies::normalise<58 Policy,59 policies::promote_float<false>,60 policies::promote_double<false>,61 policies::discrete_quantile<>,62 policies::assert_undefined<> >::type forwarding_policy;63 //64 // Whew. Now we can make the actual call to the implementation.65 // Arguments are explicitly cast to the evaluation type, and the result66 // passed through checked_narrowing_cast which handles things like overflow67 // according to the policy passed:68 //69 return policies::checked_narrowing_cast<result_type, forwarding_policy>(70 detail::polygamma_imp(n, static_cast<value_type>(x), forwarding_policy()),71 "boost::math::polygamma<%1%>(int, %1%)");72 }73 74 template<class T>75 inline typename tools::promote_args<T>::type polygamma(const int n, T x)76 {77 return boost::math::polygamma(n, x, policies::policy<>());78 }79 80} } // namespace boost::math81 82#endif // _BOOST_BERNOULLI_2013_05_30_HPP_83 84