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1 // Copyright (c) 2015 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_ELLINT_HL_HPP
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7 #define BOOST_MATH_ELLINT_HL_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/math/special_functions/math_fwd.hpp>
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14 #include <boost/math/special_functions/ellint_rj.hpp>
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15 #include <boost/math/special_functions/ellint_rj.hpp>
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16 #include <boost/math/special_functions/ellint_1.hpp>
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17 #include <boost/math/special_functions/jacobi_zeta.hpp>
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18 #include <boost/math/constants/constants.hpp>
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19 #include <boost/math/policies/error_handling.hpp>
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20 #include <boost/math/tools/workaround.hpp>
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21
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22 // Elliptic integral the Jacobi Zeta function.
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23
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24 namespace boost { namespace math {
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25
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26 namespace detail{
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27
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28 // Elliptic integral - Jacobi Zeta
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29 template <typename T, typename Policy>
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30 T heuman_lambda_imp(T phi, T k, const Policy& pol)
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31 {
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32 BOOST_MATH_STD_USING
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33 using namespace boost::math::tools;
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34 using namespace boost::math::constants;
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35
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36 const char* function = "boost::math::heuman_lambda<%1%>(%1%, %1%)";
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37
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38 if(fabs(k) > 1)
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39 return policies::raise_domain_error<T>(function, "We require |k| <= 1 but got k = %1%", k, pol);
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40
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41 T result;
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42 T sinp = sin(phi);
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43 T cosp = cos(phi);
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44 T s2 = sinp * sinp;
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45 T k2 = k * k;
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46 T kp = 1 - k2;
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47 T delta = sqrt(1 - (kp * s2));
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48 if(fabs(phi) <= constants::half_pi<T>())
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49 {
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50 result = kp * sinp * cosp / (delta * constants::half_pi<T>());
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51 result *= ellint_rf_imp(T(0), kp, T(1), pol) + k2 * ellint_rj(T(0), kp, T(1), T(1 - k2 / (delta * delta)), pol) / (3 * delta * delta);
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52 }
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53 else
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54 {
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55 T rkp = sqrt(kp);
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56 T ratio;
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57 if(rkp == 1)
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58 {
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59 return policies::raise_domain_error<T>(function, "When 1-k^2 == 1 then phi must be < Pi/2, but got phi = %1%", phi, pol);
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60 }
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61 else
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62 ratio = ellint_f_imp(phi, rkp, pol) / ellint_k_imp(rkp, pol);
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63 result = ratio + ellint_k_imp(k, pol) * jacobi_zeta_imp(phi, rkp, pol) / constants::half_pi<T>();
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64 }
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65 return result;
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66 }
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67
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68 } // detail
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69
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70 template <class T1, class T2, class Policy>
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71 inline typename tools::promote_args<T1, T2>::type heuman_lambda(T1 k, T2 phi, const Policy& pol)
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72 {
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73 typedef typename tools::promote_args<T1, T2>::type result_type;
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74 typedef typename policies::evaluation<result_type, Policy>::type value_type;
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75 return policies::checked_narrowing_cast<result_type, Policy>(detail::heuman_lambda_imp(static_cast<value_type>(phi), static_cast<value_type>(k), pol), "boost::math::heuman_lambda<%1%>(%1%,%1%)");
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76 }
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77
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78 template <class T1, class T2>
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79 inline typename tools::promote_args<T1, T2>::type heuman_lambda(T1 k, T2 phi)
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80 {
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81 return boost::math::heuman_lambda(k, phi, policies::policy<>());
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82 }
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83
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84 }} // namespaces
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85
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86 #endif // BOOST_MATH_ELLINT_D_HPP
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87
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