GNU

2017-09-15

Aliases: nextdown(3), nextdown(3), nextdown(3), nextdownf(3), nextdownf(3), nextdownf(3), nextdownl(3), nextdownl(3), nextdownl(3), nextupf(3), nextupf(3), nextupf(3), nextupl(3), nextupl(3), nextupl(3)

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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 |

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*.