aboutsummaryrefslogtreecommitdiff
path: root/libstdc++-v3/include/bits/sf_cardinal.tcc
blob: 20c58bd423d7c15b15affc4d3c609b8431dd82d2 (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
// TR29124 math special functions -*- C++ -*-
// Copyright (C) 2016 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library.  This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.

// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
// <http://www.gnu.org/licenses/>.

/** @file bits/sf_airy.tcc
 *  This is an internal header file, included by other library headers.
 *  You should not attempt to use it directly.
 */

#ifndef _GLIBCXX_BITS_SF_CARDINAL_TCC
#define _GLIBCXX_BITS_SF_CARDINAL_TCC 1

#pragma GCC system_header

#include <bits/complex_util.h>

namespace std _GLIBCXX_VISIBILITY(default)
{
// Implementation-space details.
namespace __detail
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION

  /**
   * @brief Return the sinus cardinal function
   * @f[
   *   sinc(x) = \frac{\sin(x)}{x}
   * @f]
   */
  template<typename _Tp>
    __gnu_cxx::__promote_fp_t<_Tp>
    __sinc(_Tp __x)
    {
      if (__isnan(__x))
        return __gnu_cxx::__quiet_NaN<_Tp>();
      else if (std::abs(__x) == __gnu_cxx::__infinity<_Tp>())
	return _Tp{0};
      else if (std::abs(__x) < __gnu_cxx::__sqrt_min<_Tp>())
        return _Tp{1} - __x * __x / _Tp{6};
      else
	return std::sin(__x) / __x;
    }

  /**
   * @brief Return the reperiodized sinus cardinal function
   * @f[
   *   sinc_\pi(x) = \frac{\sin(\pi x)}{\pi x}
   * @f]
   */
  template<typename _Tp>
    __gnu_cxx::__promote_fp_t<_Tp>
    __sinc_pi(_Tp __x)
    {
      constexpr auto _S_pi = __gnu_cxx::__math_constants<_Tp>::__pi;
      if (__isnan(__x))
        return __gnu_cxx::__quiet_NaN<_Tp>();
      else if (std::abs(__x) == __gnu_cxx::__infinity<_Tp>())
	return _Tp{0};
      else
	{
	  auto __arg = _S_pi * __x;
	  if (std::abs(__arg) < _Tp{4} * __gnu_cxx::__sqrt_min<_Tp>())
	    return _Tp{1} - __arg * __arg / _Tp{6};
	  else
	    return __sin_pi(__x) / __arg;
	}
    }

  /**
   * @brief Return the hyperbolic sinus cardinal function
   * @f[
   *   sinhc(x) = \frac{\sinh(x)}{x}
   * @f]
   */
  template<typename _Tp>
    __gnu_cxx::__promote_fp_t<_Tp>
    __sinhc(_Tp __x)
    {
      if (__isnan(__x))
        return __gnu_cxx::__quiet_NaN<_Tp>();
      else if (std::abs(__x) < _Tp{4} * __gnu_cxx::__sqrt_min<_Tp>())
        return _Tp{1} + __x * __x / _Tp{6};
      else
	return std::sinh(__x) / __x;
    }

  /**
   * @brief Return the reperiodized hyperbolic sinus cardinal function
   * @f[
   *   sinhc_\pi(x) = \frac{\sinh(\pi x)}{\pi x}
   * @f]
   */
  template<typename _Tp>
    __gnu_cxx::__promote_fp_t<_Tp>
    __sinhc_pi(_Tp __x)
    {
      constexpr auto _S_pi = __gnu_cxx::__math_constants<_Tp>::__pi;
      if (__isnan(__x))
        return __gnu_cxx::__quiet_NaN<_Tp>();
      else
	{
	  auto __arg = _S_pi * __x;
	  if (std::abs(__arg) < _Tp{4} * __gnu_cxx::__sqrt_min<_Tp>())
	    return _Tp{1} + __arg * __arg / _Tp{6};
	  else
	    return __sinh_pi(__x) / __arg;
	}
    }

_GLIBCXX_END_NAMESPACE_VERSION
} // namespace __detail
} // namespace std

#endif // _GLIBCXX_BITS_SF_CARDINAL_TCC