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 | |
86 | |