### nextupf (3)

#### Leading comments

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#### NAME

nextup, nextupf, nextupl, nextdown, nextdownf, nextdownl - return next floating-point number toward positive/negative infinity#### SYNOPSIS

#define _GNU_SOURCE/* See feature_test_macros(7) */#include <math.h>double nextup(doublex);float nextupf(floatx);long double nextupl(long doublex);double nextdown(doublex);float nextdownf(floatx);long double nextdownl(long doublex);Link with-lm.

#### DESCRIPTION

The**nextup**(),

**nextupf**(), and

**nextupl**() functions return the next representable floating-point number greater than

*x*.

If

*x*is the smallest representable negative number in the corresponding type, these functions return -0. If

*x*is 0, the returned value is the smallest representable positive number of the corresponding type.

If

*x*is positive infinity, the returned value is positive infinity. If

*x*is negative infinity, the returned value is the largest representable finite negative number of the corresponding type.

If

*x*is Nan, the returned value is NaN.

The value returned by

*nextdown(x)*is

*-nextup(-x)*, and similarly for the other types.

#### RETURN VALUE

See DESCRIPTION.#### VERSIONS

These functions first appeared in glibc in version 2.24.#### ATTRIBUTES

For an explanation of the terms used in this section, see**attributes(7)**.

Interface | Attribute | Value |

nextup(),
nextupf(),
nextupl(),
nextdown(),
nextdownf(),
nextdownl()
| Thread safety | MT-Safe |

#### CONFORMING TO

These functions are described in*IEEE Std 754-2008 - Standard for Floating-Point Arithmetic*and

*ISO/IEC TS 18661.*

#### SEE ALSO

**nearbyint(3)**,

**nextafter(3)**

#### COLOPHON

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