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 <boost/math/special_functions/math_fwd.hpp>
  14 #include <boost/config/no_tr1/cmath.hpp>
  15 #include <boost/math/tools/config.hpp>
  16 #include <boost/math/special_functions/trunc.hpp>
  17 #include <boost/math/tools/promotion.hpp>
  18 #include <boost/math/constants/constants.hpp>
  19
  20 namespace boost{ namespace math{ namespace detail{
  21
  22 template <class T, class Policy>
  23 T cos_pi_imp(T x, const Policy& pol)
  24 {
  25    BOOST_MATH_STD_USING // ADL of std names
  26    // cos of pi*x:
  27    bool invert = false;
  28    if(fabs(x) < 0.25)
  29       return cos(constants::pi<T>() * x);
  30
  31    if(x < 0)
  32    {
  33       x = -x;
  34    }
  35    T rem = floor(x);
  36    if(iconvert(rem, pol) & 1)
  37       invert = !invert;
  38    rem = x - rem;
  39    if(rem > 0.5f)
  40    {
  41       rem = 1 - rem;
  42       invert = !invert;
  43    }
  44    if(rem == 0.5f)
  45       return 0;
  46
  47    if(rem > 0.25f)
  48    {
  49       rem = 0.5f - rem;
  50       rem = sin(constants::pi<T>() * rem);
  51    }
  52    else
  53       rem = cos(constants::pi<T>() * rem);
  54    return invert ? T(-rem) : rem;
  55 }
  56
  57 } // namespace detail
  58
  59 template <class T, class Policy>
  60 inline typename tools::promote_args<T>::type cos_pi(T x, const Policy&)
  61 {
  62    typedef typename tools::promote_args<T>::type result_type;
  63    typedef typename policies::evaluation<result_type, Policy>::type value_type;
  64    typedef typename policies::normalise<
  65       Policy,
  66       policies::promote_float<false>,
  67       policies::promote_double<false>,
  68       policies::discrete_quantile<>,
  69       policies::assert_undefined<>,
  70       // We want to ignore overflows since the result is in [-1,1] and the
  71       // check slows the code down considerably.
  72       policies::overflow_error<policies::ignore_error> >::type forwarding_policy;
  73    return policies::checked_narrowing_cast<result_type, forwarding_policy>(boost::math::detail::cos_pi_imp<value_type>(x, forwarding_policy()), "cos_pi");
  74 }
  75
  76 template <class T>
  77 inline typename tools::promote_args<T>::type cos_pi(T x)
  78 {
  79    return boost::math::cos_pi(x, policies::policy<>());
  80 }
  81
  82 } // namespace math
  83 } // namespace boost
  84 #endif
  85