ceph/src/boost/boost/math/special_functions/cos_pi.hpp

   1 //  Copyright (c) 2007 John Maddock
   2 //  Use, modification and distribution are subject to the
   3 //  Boost Software License, Version 1.0. (See accompanying file
   4 //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   5
   6 #ifndef BOOST_MATH_COS_PI_HPP
   7 #define BOOST_MATH_COS_PI_HPP
   8
   9 #ifdef _MSC_VER
  10 #pragma once
  11 #endif
  12
  13 #include <cmath>
  14 #include <limits>
  15 #include <boost/math/special_functions/math_fwd.hpp>
  16 #include <boost/math/tools/config.hpp>
  17 #include <boost/math/special_functions/trunc.hpp>
  18 #include <boost/math/tools/promotion.hpp>
  19 #include <boost/math/constants/constants.hpp>
  20
  21 namespace boost{ namespace math{ namespace detail{
  22
  23 template <class T, class Policy>
  24 T cos_pi_imp(T x, const Policy&)
  25 {
  26    BOOST_MATH_STD_USING // ADL of std names
  27    // cos of pi*x:
  28    bool invert = false;
  29    if(fabs(x) < 0.25)
  30       return cos(constants::pi<T>() * x);
  31
  32    if(x < 0)
  33    {
  34       x = -x;
  35    }
  36    T rem = floor(x);
  37    if(abs(floor(rem/2)*2 - rem) > std::numeric_limits<T>::epsilon())
  38    {
  39       invert = !invert;
  40    }
  41    rem = x - rem;
  42    if(rem > 0.5f)
  43    {
  44       rem = 1 - rem;
  45       invert = !invert;
  46    }
  47    if(rem == 0.5f)
  48       return 0;
  49
  50    if(rem > 0.25f)
  51    {
  52       rem = 0.5f - rem;
  53       rem = sin(constants::pi<T>() * rem);
  54    }
  55    else
  56       rem = cos(constants::pi<T>() * rem);
  57    return invert ? T(-rem) : rem;
  58 }
  59
  60 } // namespace detail
  61
  62 template <class T, class Policy>
  63 inline typename tools::promote_args<T>::type cos_pi(T x, const Policy&)
  64 {
  65    typedef typename tools::promote_args<T>::type result_type;
  66    typedef typename policies::evaluation<result_type, Policy>::type value_type;
  67    typedef typename policies::normalise<
  68       Policy,
  69       policies::promote_float<false>,
  70       policies::promote_double<false>,
  71       policies::discrete_quantile<>,
  72       policies::assert_undefined<>,
  73       // We want to ignore overflows since the result is in [-1,1] and the
  74       // check slows the code down considerably.
  75       policies::overflow_error<policies::ignore_error> >::type forwarding_policy;
  76    return policies::checked_narrowing_cast<result_type, forwarding_policy>(boost::math::detail::cos_pi_imp<value_type>(x, forwarding_policy()), "cos_pi");
  77 }
  78
  79 template <class T>
  80 inline typename tools::promote_args<T>::type cos_pi(T x)
  81 {
  82    return boost::math::cos_pi(x, policies::policy<>());
  83 }
  84
  85 } // namespace math
  86 } // namespace boost
  87 #endif
  88