Manpage of NEXTAFTER

NEXTAFTER

Section: Linux Programmer's Manual (3)
Updated: 2016-03-15
Index
 

NAME

nextafter, nextafterf, nextafterl, nexttoward, nexttowardf, nexttowardl - floating-point number manipulation  

SYNOPSIS

#include <math.h>

double nextafter(double x, double y);
float nextafterf(float x, float y);
long double nextafterl(long double x, long double y);

double nexttoward(double x, long double y);
float nexttowardf(float x, long double y);
long double nexttowardl(long double x, long double y);

Link with -lm.

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

nextafter():

_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
    || _XOPEN_SOURCE >= 500
    || /* Since glibc 2.19: */ _DEFAULT_SOURCE
    || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

nextafterf(), nextafterl():
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
    || /* Since glibc 2.19: */ _DEFAULT_SOURCE
    || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

nexttoward(), nexttowardf(), nexttowardl():
_XOPEN_SOURCE >= 600 || _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
 

DESCRIPTION

The nextafter(), nextafterf(), and nextafterl() functions return the next representable floating-point value following xin the direction of y. If yis less than x, these functions will return the largest representable number less than x.

If xequals y, the functions return y.

The nexttoward(), nexttowardf(), and nexttowardl() functions do the same as the corresponding nextafter() functions, except that they have a long doublesecond argument.  

RETURN VALUE

On success, these functions return the next representable floating-point value after xin the direction of y.

If xequals y, then y(cast to the same type as x) is returned.

If xor yis a NaN, a NaN is returned.

If xis finite, and the result would overflow, a range error occurs, and the functions return HUGE_VAL, HUGE_VALF, or HUGE_VALL, respectively, with the correct mathematical sign.

If xis not equal to y, and the correct function result would be subnormal, zero, or underflow, a range error occurs, and either the correct value (if it can be represented), or 0.0, is returned.  

ERRORS

See math_error(7) for information on how to determine whether an error has occurred when calling these functions.

The following errors can occur:

Range error: result overflow
An overflow floating-point exception (FE_OVERFLOW) is raised.
Range error: result is subnormal or underflows
An underflow floating-point exception (FE_UNDERFLOW) is raised.

These functions do not set errno.  

ATTRIBUTES

For an explanation of the terms used in this section, see attributes(7).
InterfaceAttributeValue
nextafter(), nextafterf(),
nextafterl(), nexttoward(),
nexttowardf(), nexttowardl()
Thread safetyMT-Safe
 

CONFORMING TO

C99, POSIX.1-2001, POSIX.1-2008. This function is defined in IEC 559 (and the appendix with recommended functions in IEEE 754/IEEE 854).  

BUGS

In glibc version 2.5 and earlier, these functions do not raise an underflow floating-point (FE_UNDERFLOW) exception when an underflow occurs.  

SEE ALSO

nearbyint(3)


 

Index

NAME
SYNOPSIS
DESCRIPTION
RETURN VALUE
ERRORS
ATTRIBUTES
CONFORMING TO
BUGS
SEE ALSO

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