Chris@16: //  Copyright (c) 2007 John Maddock
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_SIN_PI_HPP
Chris@16: #define BOOST_MATH_SIN_PI_HPP
Chris@16: 
Chris@16: #ifdef _MSC_VER
Chris@16: #pragma once
Chris@16: #endif
Chris@16: 
Chris@16: #include <boost/config/no_tr1/cmath.hpp>
Chris@16: #include <boost/math/tools/config.hpp>
Chris@101: #include <boost/math/special_functions/math_fwd.hpp>
Chris@16: #include <boost/math/special_functions/trunc.hpp>
Chris@16: #include <boost/math/tools/promotion.hpp>
Chris@16: #include <boost/math/constants/constants.hpp>
Chris@16: 
Chris@16: namespace boost{ namespace math{ namespace detail{
Chris@16: 
Chris@16: template <class T, class Policy>
Chris@16: T sin_pi_imp(T x, const Policy& pol)
Chris@16: {
Chris@16:    BOOST_MATH_STD_USING // ADL of std names
Chris@16:    if(x < 0)
Chris@16:       return -sin_pi(-x);
Chris@16:    // sin of pi*x:
Chris@16:    bool invert;
Chris@16:    if(x < 0.5)
Chris@16:       return sin(constants::pi<T>() * x);
Chris@16:    if(x < 1)
Chris@16:    {
Chris@16:       invert = true;
Chris@16:       x = -x;
Chris@16:    }
Chris@16:    else
Chris@16:       invert = false;
Chris@16: 
Chris@16:    T rem = floor(x);
Chris@16:    if(itrunc(rem, pol) & 1)
Chris@16:       invert = !invert;
Chris@16:    rem = x - rem;
Chris@16:    if(rem > 0.5f)
Chris@16:       rem = 1 - rem;
Chris@16:    if(rem == 0.5f)
Chris@16:       return static_cast<T>(invert ? -1 : 1);
Chris@16:    
Chris@16:    rem = sin(constants::pi<T>() * rem);
Chris@16:    return invert ? T(-rem) : rem;
Chris@16: }
Chris@16: 
Chris@16: } // namespace detail
Chris@16: 
Chris@16: template <class T, class Policy>
Chris@101: inline typename tools::promote_args<T>::type sin_pi(T x, const Policy&)
Chris@16: {
Chris@16:    typedef typename tools::promote_args<T>::type result_type;
Chris@101:    typedef typename policies::evaluation<result_type, Policy>::type value_type;
Chris@101:    typedef typename policies::normalise<
Chris@101:       Policy,
Chris@101:       policies::promote_float<false>,
Chris@101:       policies::promote_double<false>,
Chris@101:       policies::discrete_quantile<>,
Chris@101:       policies::assert_undefined<> >::type forwarding_policy;
Chris@101:    return policies::checked_narrowing_cast<result_type, forwarding_policy>(boost::math::detail::sin_pi_imp<value_type>(x, forwarding_policy()), "cos_pi");
Chris@16: }
Chris@16: 
Chris@16: template <class T>
Chris@16: inline typename tools::promote_args<T>::type sin_pi(T x)
Chris@16: {
Chris@16:    return boost::math::sin_pi(x, policies::policy<>());
Chris@16: }
Chris@16: 
Chris@16: } // namespace math
Chris@16: } // namespace boost
Chris@16: #endif
Chris@16: