golden hour

/usr/include/c++/4.8.2/tr1

File/Folder	Size	Actions
array	6.8 KB
bessel_function.tcc	21.6 KB
beta_function.tcc	5.47 KB
ccomplex	1.23 KB
cctype	1.38 KB
cfenv	1.96 KB
cfloat	1.35 KB
cinttypes	2.2 KB
climits	1.42 KB
cmath	36.55 KB
complex	12.04 KB
complex.h	1.23 KB
cstdarg	1.22 KB
cstdbool	1.31 KB
cstdint	2.56 KB
cstdio	1.44 KB
cstdlib	1.74 KB
ctgmath	1.22 KB
ctime	1.21 KB
ctype.h	1.18 KB
cwchar	1.67 KB
cwctype	1.42 KB
ell_integral.tcc	26.85 KB
exp_integral.tcc	15.41 KB
fenv.h	1.18 KB
float.h	1.18 KB
functional	69.15 KB
functional_hash.h	5.7 KB
gamma.tcc	13.97 KB
hashtable.h	40.56 KB
hashtable_policy.h	24.64 KB
hypergeometric.tcc	27.07 KB
inttypes.h	1.24 KB
legendre_function.tcc	10.32 KB
limits.h	1.19 KB
math.h	4.45 KB
memory	1.75 KB
modified_bessel_func.tcc	15.35 KB
poly_hermite.tcc	3.61 KB
poly_laguerre.tcc	11.08 KB
random	1.55 KB
random.h	71.48 KB
random.tcc	52.73 KB
regex	90.77 KB
riemann_zeta.tcc	13.34 KB
shared_ptr.h	31.91 KB
special_function_util.h	4.71 KB
stdarg.h	1.19 KB
stdbool.h	1.19 KB
stdint.h	1.19 KB
stdio.h	1.18 KB
stdlib.h	1.45 KB
tgmath.h	1.23 KB
tuple	11.83 KB
type_traits	18.57 KB
unordered_map	1.54 KB
unordered_map.h	9.98 KB
unordered_set	1.54 KB
unordered_set.h	9.32 KB
utility	3.15 KB
wchar.h	1.22 KB
wctype.h	1.23 KB

Edit: special_function_util.h

// Special functions -*- C++ -*-

// Copyright (C) 2006-2013 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 tr1/special_function_util.h
 *  This is an internal header file, included by other library headers.
 *  Do not attempt to use it directly. @headername{tr1/cmath}
 */

//
// ISO C++ 14882 TR1: 5.2  Special functions
//

// Written by Edward Smith-Rowland based on numerous mathematics books.

#ifndef _GLIBCXX_TR1_SPECIAL_FUNCTION_UTIL_H
#define _GLIBCXX_TR1_SPECIAL_FUNCTION_UTIL_H 1

namespace std _GLIBCXX_VISIBILITY(default)
{
namespace tr1
{
  namespace __detail
  {
  _GLIBCXX_BEGIN_NAMESPACE_VERSION

/// A class to encapsulate type dependent floating point
    /// constants.  Not everything will be able to be expressed as
    /// type logic.
    template<typename _Tp>
    struct __floating_point_constant
    {
      static const _Tp __value;
    };

/// A structure for numeric constants.
    template<typename _Tp>
      struct __numeric_constants
      {
        ///  Constant @f$ \pi @f$.
        static _Tp __pi() throw()
        { return static_cast<_Tp>(3.1415926535897932384626433832795029L); }
        ///  Constant @f$ \pi / 2 @f$.
        static _Tp __pi_2() throw()
        { return static_cast<_Tp>(1.5707963267948966192313216916397514L); }
        ///  Constant @f$ \pi / 3 @f$.
        static _Tp __pi_3() throw()
        { return static_cast<_Tp>(1.0471975511965977461542144610931676L); }
        ///  Constant @f$ \pi / 4 @f$.
        static _Tp __pi_4() throw()
        { return static_cast<_Tp>(0.7853981633974483096156608458198757L); }
        ///  Constant @f$ 1 / \pi @f$.
        static _Tp __1_pi() throw()
        { return static_cast<_Tp>(0.3183098861837906715377675267450287L); }
        ///  Constant @f$ 2 / \sqrt(\pi) @f$.
        static _Tp __2_sqrtpi() throw()
        { return static_cast<_Tp>(1.1283791670955125738961589031215452L); }
        ///  Constant @f$ \sqrt(2) @f$.
        static _Tp __sqrt2() throw()
        { return static_cast<_Tp>(1.4142135623730950488016887242096981L); }
        ///  Constant @f$ \sqrt(3) @f$.
        static _Tp __sqrt3() throw()
        { return static_cast<_Tp>(1.7320508075688772935274463415058723L); }
        ///  Constant @f$ \sqrt(\pi/2) @f$.
        static _Tp __sqrtpio2() throw()
        { return static_cast<_Tp>(1.2533141373155002512078826424055226L); }
        ///  Constant @f$ 1 / sqrt(2) @f$.
        static _Tp __sqrt1_2() throw()
        { return static_cast<_Tp>(0.7071067811865475244008443621048490L); }
        ///  Constant @f$ \log(\pi) @f$.
        static _Tp __lnpi() throw()
        { return static_cast<_Tp>(1.1447298858494001741434273513530587L); }
        ///  Constant Euler's constant @f$ \gamma_E @f$.
        static _Tp __gamma_e() throw()
        { return static_cast<_Tp>(0.5772156649015328606065120900824024L); }
        ///  Constant Euler-Mascheroni @f$ e @f$
        static _Tp __euler() throw()
        { return static_cast<_Tp>(2.7182818284590452353602874713526625L); }
      };

#if _GLIBCXX_USE_C99_MATH && !_GLIBCXX_USE_C99_FP_MACROS_DYNAMIC

/// This is a wrapper for the isnan function. Otherwise, for NaN,
    /// all comparisons result in false. If/when we build a std::isnan
    /// out of intrinsics, this will disappear completely in favor of
    /// std::isnan.
    template<typename _Tp>
    inline bool __isnan(_Tp __x)
    { return std::isnan(__x); }

#else

template<typename _Tp>
    inline bool __isnan(const _Tp __x)
    { return __builtin_isnan(__x); }

template<>
    inline bool __isnan<float>(float __x)
    { return __builtin_isnanf(__x); }

template<>
    inline bool __isnan<long double>(long double __x)
    { return __builtin_isnanl(__x); }

#endif

_GLIBCXX_END_NAMESPACE_VERSION
  } // namespace __detail
}
}

#endif // _GLIBCXX_TR1_SPECIAL_FUNCTION_UTIL_H