# NEXTAFTER(3) - man page online | library functions

Floating-point number manipulation.

Chapter

2015-04-19

NEXTAFTER(3) Linux Programmer's Manual NEXTAFTER(3)## 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(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 500 || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED || _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L; or cc -std=c99 nextafterf(), nextafterl(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L; or cc -std=c99 nexttoward(), nexttowardf(), nexttowardl(): _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L; or cc -std=c99## DESCRIPTION

The nextafter(), nextafterf(), and nextafterl() functions return the next representable floating-point value following x in the direction of y. If y is less than x, these func‐ tions will return the largest representable number less than x. If x equals y, the functions return y. The nexttoward(), nexttowardf(), and nexttowardl() functions do the same as the corre‐ sponding nextafter() functions, except that they have a long double second argument.## RETURN VALUE

On success, these functions return the next representable floating-point value after x in the direction of y. If x equals y, then y (cast to the same type as x) is returned. If x or y is a NaN, a NaN is returned. If x is 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 x is 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). ┌─────────────────────────────┬───────────────┬─────────┐ │Interface │ Attribute │ Value │ ├─────────────────────────────┼───────────────┼─────────┤ │nextafter(), nextafterf(), │ Thread safety │ MT-Safe │ │nextafterl(), nexttoward(), │ │ │ │nexttowardf(), nexttowardl() │ │ │ └─────────────────────────────┴───────────────┴─────────┘## 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)## COLOPHON

This page is part of release 4.04 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at http://www.kernel.org/doc/man-pages/.GNU 2015-04-19 NEXTAFTER(3)

This manual | Reference | Other manuals |

nextafter(3) | referred by | |

refer to | attributes(7) | feature_test_macros(7) | math_error(7) | rint(3) |