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1 // Copyright (c) 2007 John Maddock
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2 // Use, modification and distribution are subject to the
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3 // Boost Software License, Version 1.0. (See accompanying file
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4 // LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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5
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6 #ifndef BOOST_MATH_SIN_PI_HPP
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7 #define BOOST_MATH_SIN_PI_HPP
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8
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9 #ifdef _MSC_VER
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10 #pragma once
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11 #endif
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12
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13 #include <boost/config/no_tr1/cmath.hpp>
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14 #include <boost/math/tools/config.hpp>
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15 #include <boost/math/special_functions/math_fwd.hpp>
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16 #include <boost/math/special_functions/trunc.hpp>
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17 #include <boost/math/tools/promotion.hpp>
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18 #include <boost/math/constants/constants.hpp>
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19
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20 namespace boost{ namespace math{ namespace detail{
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21
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22 template <class T, class Policy>
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23 T sin_pi_imp(T x, const Policy& pol)
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24 {
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25 BOOST_MATH_STD_USING // ADL of std names
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26 if(x < 0)
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27 return -sin_pi(-x);
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28 // sin of pi*x:
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29 bool invert;
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30 if(x < 0.5)
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31 return sin(constants::pi<T>() * x);
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32 if(x < 1)
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33 {
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34 invert = true;
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35 x = -x;
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36 }
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37 else
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38 invert = false;
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39
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40 T rem = floor(x);
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41 if(itrunc(rem, pol) & 1)
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42 invert = !invert;
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43 rem = x - rem;
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44 if(rem > 0.5f)
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45 rem = 1 - rem;
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46 if(rem == 0.5f)
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47 return static_cast<T>(invert ? -1 : 1);
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48
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49 rem = sin(constants::pi<T>() * rem);
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50 return invert ? T(-rem) : rem;
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51 }
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52
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53 } // namespace detail
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54
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55 template <class T, class Policy>
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56 inline typename tools::promote_args<T>::type sin_pi(T x, const Policy&)
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57 {
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58 typedef typename tools::promote_args<T>::type result_type;
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59 typedef typename policies::evaluation<result_type, Policy>::type value_type;
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60 typedef typename policies::normalise<
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61 Policy,
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62 policies::promote_float<false>,
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63 policies::promote_double<false>,
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64 policies::discrete_quantile<>,
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65 policies::assert_undefined<> >::type forwarding_policy;
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66 return policies::checked_narrowing_cast<result_type, forwarding_policy>(boost::math::detail::sin_pi_imp<value_type>(x, forwarding_policy()), "cos_pi");
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67 }
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68
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69 template <class T>
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70 inline typename tools::promote_args<T>::type sin_pi(T x)
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71 {
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72 return boost::math::sin_pi(x, policies::policy<>());
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73 }
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74
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75 } // namespace math
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76 } // namespace boost
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77 #endif
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78
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