Chris@16: //  (C) Copyright John Maddock 2006.
Chris@16: //  Use, modification and distribution are subject to the
Chris@16: //  Boost Software License, Version 1.0. (See accompanying file
Chris@16: //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
Chris@16: 
Chris@16: #ifndef BOOST_MATH_POWM1
Chris@16: #define BOOST_MATH_POWM1
Chris@16: 
Chris@16: #ifdef _MSC_VER
Chris@16: #pragma once
Chris@16: #endif
Chris@16: 
Chris@101: #include <boost/math/special_functions/math_fwd.hpp>
Chris@16: #include <boost/math/special_functions/log1p.hpp>
Chris@16: #include <boost/math/special_functions/expm1.hpp>
Chris@16: #include <boost/assert.hpp>
Chris@16: 
Chris@16: namespace boost{ namespace math{ namespace detail{
Chris@16: 
Chris@16: template <class T, class Policy>
Chris@16: inline T powm1_imp(const T a, const T z, const Policy& pol)
Chris@16: {
Chris@16:    BOOST_MATH_STD_USING
Chris@16: 
Chris@16:    if((fabs(a) < 1) || (fabs(z) < 1))
Chris@16:    {
Chris@16:       T p = log(a) * z;
Chris@16:       if(fabs(p) < 2)
Chris@16:          return boost::math::expm1(p, pol);
Chris@16:       // otherwise fall though:
Chris@16:    }
Chris@16:    return pow(a, z) - 1;
Chris@16: }
Chris@16: 
Chris@16: } // detail
Chris@16: 
Chris@16: template <class T1, class T2>
Chris@16: inline typename tools::promote_args<T1, T2>::type 
Chris@16:    powm1(const T1 a, const T2 z)
Chris@16: {
Chris@16:    typedef typename tools::promote_args<T1, T2>::type result_type;
Chris@16:    return detail::powm1_imp(static_cast<result_type>(a), static_cast<result_type>(z), policies::policy<>());
Chris@16: }
Chris@16: 
Chris@16: template <class T1, class T2, class Policy>
Chris@16: inline typename tools::promote_args<T1, T2>::type 
Chris@16:    powm1(const T1 a, const T2 z, const Policy& pol)
Chris@16: {
Chris@16:    typedef typename tools::promote_args<T1, T2>::type result_type;
Chris@16:    return detail::powm1_imp(static_cast<result_type>(a), static_cast<result_type>(z), pol);
Chris@16: }
Chris@16: 
Chris@16: } // namespace math
Chris@16: } // namespace boost
Chris@16: 
Chris@16: #endif // BOOST_MATH_POWM1
Chris@16: 
Chris@16: 
Chris@16: 
Chris@16: 
Chris@16: