third_party/boost/core/doc/cmath.qbk

[/
  Copyright 2018 Peter Dimov

  Distributed under the Boost Software License, Version 1.0.

  See accompanying file LICENSE_1_0.txt
  or copy at http://boost.org/LICENSE_1_0.txt
]

[section:cmath cmath]

[simplesect Authors]

* Peter Dimov

[endsimplesect]

[section Header <boost/core/cmath.hpp>]

The header `<boost/core/cmath.hpp>` defines, in a portable way, the floating
point classification and sign manipulation functions from C++11.

[section Synopsis]

``
namespace boost
{
namespace core
{

// fpclassify return values

int const fp_zero = /*unspecified*/;
int const fp_subnormal = /*unspecified*/;
int const fp_normal = /*unspecified*/;
int const fp_infinite = /*unspecified*/;
int const fp_nan = /*unspecified*/;

// Classification functions

template<class T> bool isfinite( T x );
template<class T> bool isnan( T x );
template<class T> bool isinf( T x );
template<class T> bool isnormal( T x );
template<class T> int fpclassify( T x );

// Sign manipulation functions

template<class T> bool signbit( T x );
template<class T> T copysign( T x, T y );

} // namespace core
} // namespace boost
``

[endsect]

[section Classification Functions]

[section template<class T> bool isfinite( T x );]

* *Requires:* `T` must be `float`, `double`, or `long double`.
* *Returns:* `true` when `x` is finite (not infinity or NaN), `false` otherwise.

[endsect]

[section template<class T> bool isnan( T x );]

* *Requires:* `T` must be `float`, `double`, or `long double`.
* *Returns:* `true` when `x` is NaN, `false` otherwise.

[endsect]

[section template<class T> bool isinf( T x );]

* *Requires:* `T` must be `float`, `double`, or `long double`.
* *Returns:* `true` when `x` is infinity, `false` otherwise.

[endsect]

[section template<class T> bool isnormal( T x );]

* *Requires:* `T` must be `float`, `double`, or `long double`.
* *Returns:* `true` when `x` is a normal number (not zero, subnormal, infinity, or NaN), `false` otherwise.

[endsect]

[section template<class T> int fpclassify( T x );]

* *Requires:* `T` must be `float`, `double`, or `long double`.
* *Returns:*
  * `fp_zero` when `x` is zero;
  * `fp_subnormal` when `x` is subnormal;
  * `fp_infinite` when `x` is infinity;
  * `fp_nan` when `x` is NaN;
  * `fp_normal` otherwise.

[endsect]

[endsect]

[section Sign Manipulation Functions]

[section template<class T> bool signbit( T x );]

* *Requires:* `T` must be `float`, `double`, or `long double`.
* *Returns:* `true` when `x` is negative, `false` otherwise.

[endsect]

[section template<class T> bool copysign( T x, T y );]

* *Requires:* `T` must be `float`, `double`, or `long double`.
* *Returns:* `x` with the sign copied from `y`.

[endsect]

[endsect]

[endsect]

[endsect]