Chris@102: 
Chris@102: ///////////////////////////////////////////////////////////////////////////////
Chris@102: //  Copyright 2013 Nikhar Agrawal
Chris@102: //  Copyright 2013 Christopher Kormanyos
Chris@102: //  Copyright 2014 John Maddock
Chris@102: //  Copyright 2013 Paul Bristow
Chris@102: //  Distributed under the Boost
Chris@102: //  Software License, Version 1.0. (See accompanying file
Chris@102: //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
Chris@102: 
Chris@102: #ifndef _BOOST_POLYGAMMA_2013_07_30_HPP_
Chris@102:   #define _BOOST_POLYGAMMA_2013_07_30_HPP_
Chris@102: 
Chris@102: #include <boost/math/special_functions/factorials.hpp>
Chris@102: #include <boost/math/special_functions/detail/polygamma.hpp>
Chris@102: #include <boost/math/special_functions/trigamma.hpp>
Chris@102: 
Chris@102: namespace boost { namespace math {
Chris@102: 
Chris@102:   
Chris@102:   template<class T, class Policy>
Chris@102:   inline typename tools::promote_args<T>::type polygamma(const int n, T x, const Policy& pol)
Chris@102:   {
Chris@102:      //
Chris@102:      // Filter off special cases right at the start:
Chris@102:      //
Chris@102:      if(n == 0)
Chris@102:         return boost::math::digamma(x, pol);
Chris@102:      if(n == 1)
Chris@102:         return boost::math::trigamma(x, pol);
Chris@102:      //
Chris@102:      // We've found some standard library functions to misbehave if any FPU exception flags
Chris@102:      // are set prior to their call, this code will clear those flags, then reset them
Chris@102:      // on exit:
Chris@102:      //
Chris@102:      BOOST_FPU_EXCEPTION_GUARD
Chris@102:      //
Chris@102:      // The type of the result - the common type of T and U after
Chris@102:      // any integer types have been promoted to double:
Chris@102:      //
Chris@102:      typedef typename tools::promote_args<T>::type result_type;
Chris@102:      //
Chris@102:      // The type used for the calculation.  This may be a wider type than
Chris@102:      // the result in order to ensure full precision:
Chris@102:      //
Chris@102:      typedef typename policies::evaluation<result_type, Policy>::type value_type;
Chris@102:      //
Chris@102:      // The type of the policy to forward to the actual implementation.
Chris@102:      // We disable promotion of float and double as that's [possibly]
Chris@102:      // happened already in the line above.  Also reset to the default
Chris@102:      // any policies we don't use (reduces code bloat if we're called
Chris@102:      // multiple times with differing policies we don't actually use).
Chris@102:      // Also normalise the type, again to reduce code bloat in case we're
Chris@102:      // called multiple times with functionally identical policies that happen
Chris@102:      // to be different types.
Chris@102:      //
Chris@102:      typedef typename policies::normalise<
Chris@102:         Policy,
Chris@102:         policies::promote_float<false>,
Chris@102:         policies::promote_double<false>,
Chris@102:         policies::discrete_quantile<>,
Chris@102:         policies::assert_undefined<> >::type forwarding_policy;
Chris@102:      //
Chris@102:      // Whew.  Now we can make the actual call to the implementation.
Chris@102:      // Arguments are explicitly cast to the evaluation type, and the result
Chris@102:      // passed through checked_narrowing_cast which handles things like overflow
Chris@102:      // according to the policy passed:
Chris@102:      //
Chris@102:      return policies::checked_narrowing_cast<result_type, forwarding_policy>(
Chris@102:         detail::polygamma_imp(n, static_cast<value_type>(x), forwarding_policy()),
Chris@102:         "boost::math::polygamma<%1%>(int, %1%)");
Chris@102:   }
Chris@102: 
Chris@102:   template<class T>
Chris@102:   inline typename tools::promote_args<T>::type polygamma(const int n, T x)
Chris@102:   {
Chris@102:       return boost::math::polygamma(n, x, policies::policy<>());
Chris@102:   }
Chris@102: 
Chris@102: } } // namespace boost::math
Chris@102: 
Chris@102: #endif // _BOOST_BERNOULLI_2013_05_30_HPP_
Chris@102: