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1 // boost sinhc.hpp header file
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2
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3 // (C) Copyright Hubert Holin 2001.
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4 // Distributed under the Boost Software License, Version 1.0. (See
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5 // accompanying file LICENSE_1_0.txt or copy at
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6 // http://www.boost.org/LICENSE_1_0.txt)
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7
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8 // See http://www.boost.org for updates, documentation, and revision history.
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9
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10 #ifndef BOOST_SINHC_HPP
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11 #define BOOST_SINHC_HPP
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12
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13
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14 #ifdef _MSC_VER
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15 #pragma once
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16 #endif
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17
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18 #include <boost/math/tools/config.hpp>
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19 #include <boost/math/tools/precision.hpp>
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20 #include <boost/math/special_functions/math_fwd.hpp>
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21 #include <boost/config/no_tr1/cmath.hpp>
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22 #include <boost/limits.hpp>
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23 #include <string>
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24 #include <stdexcept>
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25
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26 #include <boost/config.hpp>
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27
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28
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29 // These are the the "Hyperbolic Sinus Cardinal" functions.
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30
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31 namespace boost
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32 {
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33 namespace math
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34 {
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35 namespace detail
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36 {
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37 #if defined(__GNUC__) && (__GNUC__ < 3)
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38 // gcc 2.x ignores function scope using declarations,
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39 // put them in the scope of the enclosing namespace instead:
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40
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41 using ::std::abs;
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42 using ::std::sqrt;
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43 using ::std::sinh;
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44
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45 using ::std::numeric_limits;
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46 #endif /* defined(__GNUC__) && (__GNUC__ < 3) */
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47
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48 // This is the "Hyperbolic Sinus Cardinal" of index Pi.
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49
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50 template<typename T>
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51 inline T sinhc_pi_imp(const T x)
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52 {
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53 #if defined(BOOST_NO_STDC_NAMESPACE) && !defined(__SUNPRO_CC)
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54 using ::abs;
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55 using ::sinh;
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56 using ::sqrt;
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57 #else /* BOOST_NO_STDC_NAMESPACE */
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58 using ::std::abs;
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59 using ::std::sinh;
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60 using ::std::sqrt;
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61 #endif /* BOOST_NO_STDC_NAMESPACE */
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62
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63 static T const taylor_0_bound = tools::epsilon<T>();
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64 static T const taylor_2_bound = sqrt(taylor_0_bound);
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65 static T const taylor_n_bound = sqrt(taylor_2_bound);
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66
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67 if (abs(x) >= taylor_n_bound)
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68 {
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69 return(sinh(x)/x);
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70 }
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71 else
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72 {
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73 // approximation by taylor series in x at 0 up to order 0
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74 T result = static_cast<T>(1);
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75
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76 if (abs(x) >= taylor_0_bound)
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77 {
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78 T x2 = x*x;
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79
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80 // approximation by taylor series in x at 0 up to order 2
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81 result += x2/static_cast<T>(6);
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82
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83 if (abs(x) >= taylor_2_bound)
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84 {
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85 // approximation by taylor series in x at 0 up to order 4
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86 result += (x2*x2)/static_cast<T>(120);
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87 }
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88 }
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89
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90 return(result);
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91 }
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92 }
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93
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94 } // namespace detail
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95
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96 template <class T>
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97 inline typename tools::promote_args<T>::type sinhc_pi(T x)
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98 {
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99 typedef typename tools::promote_args<T>::type result_type;
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100 return detail::sinhc_pi_imp(static_cast<result_type>(x));
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101 }
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102
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103 template <class T, class Policy>
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104 inline typename tools::promote_args<T>::type sinhc_pi(T x, const Policy&)
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105 {
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106 return boost::math::sinhc_pi(x);
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107 }
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108
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109 #ifdef BOOST_NO_TEMPLATE_TEMPLATES
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110 #else /* BOOST_NO_TEMPLATE_TEMPLATES */
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111 template<typename T, template<typename> class U>
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112 inline U<T> sinhc_pi(const U<T> x)
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113 {
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114 #if defined(BOOST_FUNCTION_SCOPE_USING_DECLARATION_BREAKS_ADL) || defined(__GNUC__)
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115 using namespace std;
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116 #elif defined(BOOST_NO_STDC_NAMESPACE) && !defined(__SUNPRO_CC)
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117 using ::abs;
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118 using ::sinh;
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119 using ::sqrt;
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120 #else /* BOOST_NO_STDC_NAMESPACE */
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121 using ::std::abs;
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122 using ::std::sinh;
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123 using ::std::sqrt;
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124 #endif /* BOOST_NO_STDC_NAMESPACE */
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125
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126 using ::std::numeric_limits;
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127
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128 static T const taylor_0_bound = tools::epsilon<T>();
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129 static T const taylor_2_bound = sqrt(taylor_0_bound);
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130 static T const taylor_n_bound = sqrt(taylor_2_bound);
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131
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132 if (abs(x) >= taylor_n_bound)
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133 {
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134 return(sinh(x)/x);
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135 }
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136 else
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137 {
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138 // approximation by taylor series in x at 0 up to order 0
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139 #ifdef __MWERKS__
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140 U<T> result = static_cast<U<T> >(1);
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141 #else
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142 U<T> result = U<T>(1);
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143 #endif
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144
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145 if (abs(x) >= taylor_0_bound)
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146 {
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147 U<T> x2 = x*x;
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148
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149 // approximation by taylor series in x at 0 up to order 2
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150 result += x2/static_cast<T>(6);
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151
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152 if (abs(x) >= taylor_2_bound)
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153 {
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154 // approximation by taylor series in x at 0 up to order 4
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155 result += (x2*x2)/static_cast<T>(120);
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156 }
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157 }
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158
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159 return(result);
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160 }
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161 }
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162 #endif /* BOOST_NO_TEMPLATE_TEMPLATES */
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163 }
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164 }
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165
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166 #endif /* BOOST_SINHC_HPP */
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167
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