summaryrefslogtreecommitdiff
path: root/boost/math/special_functions/sinhc.hpp
blob: 1216b7bfb78d910439ec7f9a018765e7d9c2cef5 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
//  boost sinhc.hpp header file

//  (C) Copyright Hubert Holin 2001.
//  Distributed under the Boost Software License, Version 1.0. (See
//  accompanying file LICENSE_1_0.txt or copy at
//  http://www.boost.org/LICENSE_1_0.txt)

// See http://www.boost.org for updates, documentation, and revision history.

#ifndef BOOST_SINHC_HPP
#define BOOST_SINHC_HPP


#ifdef _MSC_VER
#pragma once
#endif

#include <boost/math/tools/config.hpp>
#include <boost/math/tools/precision.hpp>
#include <boost/math/special_functions/math_fwd.hpp>
#include <boost/config/no_tr1/cmath.hpp>
#include <boost/limits.hpp>
#include <string>
#include <stdexcept>

#include <boost/config.hpp>


// These are the the "Hyperbolic Sinus Cardinal" functions.

namespace boost
{
    namespace math
    {
       namespace detail
       {
        // This is the "Hyperbolic Sinus Cardinal" of index Pi.

        template<typename T>
        inline T    sinhc_pi_imp(const T x)
        {
#if defined(BOOST_NO_STDC_NAMESPACE) && !defined(__SUNPRO_CC)
            using    ::abs;
            using    ::sinh;
            using    ::sqrt;
#else    /* BOOST_NO_STDC_NAMESPACE */
            using    ::std::abs;
            using    ::std::sinh;
            using    ::std::sqrt;
#endif    /* BOOST_NO_STDC_NAMESPACE */

            static T const    taylor_0_bound = tools::epsilon<T>();
            static T const    taylor_2_bound = sqrt(taylor_0_bound);
            static T const    taylor_n_bound = sqrt(taylor_2_bound);

            if    (abs(x) >= taylor_n_bound)
            {
                return(sinh(x)/x);
            }
            else
            {
                // approximation by taylor series in x at 0 up to order 0
                T    result = static_cast<T>(1);

                if    (abs(x) >= taylor_0_bound)
                {
                    T    x2 = x*x;

                    // approximation by taylor series in x at 0 up to order 2
                    result += x2/static_cast<T>(6);

                    if    (abs(x) >= taylor_2_bound)
                    {
                        // approximation by taylor series in x at 0 up to order 4
                        result += (x2*x2)/static_cast<T>(120);
                    }
                }

                return(result);
            }
        }

       } // namespace detail

       template <class T>
       inline typename tools::promote_args<T>::type sinhc_pi(T x)
       {
          typedef typename tools::promote_args<T>::type result_type;
          return detail::sinhc_pi_imp(static_cast<result_type>(x));
       }

       template <class T, class Policy>
       inline typename tools::promote_args<T>::type sinhc_pi(T x, const Policy&)
       {
          return boost::math::sinhc_pi(x);
       }

#ifdef    BOOST_NO_TEMPLATE_TEMPLATES
#else    /* BOOST_NO_TEMPLATE_TEMPLATES */
        template<typename T, template<typename> class U>
        inline U<T>    sinhc_pi(const U<T> x)
        {
#if defined(BOOST_FUNCTION_SCOPE_USING_DECLARATION_BREAKS_ADL) || defined(__GNUC__)
            using namespace std;
#elif    defined(BOOST_NO_STDC_NAMESPACE) && !defined(__SUNPRO_CC)
            using    ::abs;
            using    ::sinh;
            using    ::sqrt;
#else    /* BOOST_NO_STDC_NAMESPACE */
            using    ::std::abs;
            using    ::std::sinh;
            using    ::std::sqrt;
#endif    /* BOOST_NO_STDC_NAMESPACE */

            using    ::std::numeric_limits;

            static T const    taylor_0_bound = tools::epsilon<T>();
            static T const    taylor_2_bound = sqrt(taylor_0_bound);
            static T const    taylor_n_bound = sqrt(taylor_2_bound);

            if    (abs(x) >= taylor_n_bound)
            {
                return(sinh(x)/x);
            }
            else
            {
                // approximation by taylor series in x at 0 up to order 0
#ifdef __MWERKS__
                U<T>    result = static_cast<U<T> >(1);
#else
                U<T>    result = U<T>(1);
#endif

                if    (abs(x) >= taylor_0_bound)
                {
                    U<T>    x2 = x*x;

                    // approximation by taylor series in x at 0 up to order 2
                    result += x2/static_cast<T>(6);

                    if    (abs(x) >= taylor_2_bound)
                    {
                        // approximation by taylor series in x at 0 up to order 4
                        result += (x2*x2)/static_cast<T>(120);
                    }
                }

                return(result);
            }
        }
#endif    /* BOOST_NO_TEMPLATE_TEMPLATES */
    }
}

#endif /* BOOST_SINHC_HPP */