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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(itrunc(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<> >::type forwarding_policy; | |
70 | return policies::checked_narrowing_cast<result_type, forwarding_policy>(boost::math::detail::cos_pi_imp<value_type>(x, forwarding_policy()), "cos_pi"); | |
71 | } | |
72 | ||
73 | template <class T> | |
74 | inline typename tools::promote_args<T>::type cos_pi(T x) | |
75 | { | |
76 | return boost::math::cos_pi(x, policies::policy<>()); | |
77 | } | |
78 | ||
79 | } // namespace math | |
80 | } // namespace boost | |
81 | #endif | |
82 |