nextup(3) — Linux manual page


nextup(3)               Library Functions Manual               nextup(3)

NAME         top

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

LIBRARY         top

       Math library (libm, -lm)

SYNOPSIS         top

       #define _GNU_SOURCE     /* See feature_test_macros(7) */
       #include <math.h>

       double nextup(double x);
       float nextupf(float x);
       long double nextupl(long double x);

       double nextdown(double x);
       float nextdownf(float x);
       long double nextdownl(long double x);

DESCRIPTION         top

       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

       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         top


ATTRIBUTES         top

       For an explanation of the terms used in this section, see
       │ Interface                           Attribute     Value   │
       │ nextup(), nextupf(), nextupl(),     │ Thread safety │ MT-Safe │
       │ nextdown(), nextdownf(),            │               │         │
       │ nextdownl()                         │               │         │

STANDARDS         top

       These functions are described in IEEE Std 754-2008 - Standard for
       Floating-Point Arithmetic and ISO/IEC TS 18661.

HISTORY         top

       glibc 2.24.

SEE ALSO         top

       nearbyint(3), nextafter(3)

COLOPHON         top

       This page is part of the man-pages (Linux kernel and C library
       user-space interface documentation) project.  Information about
       the project can be found at 
       ⟨⟩.  If you have a bug report
       for this manual page, see
       This page was obtained from the tarball man-pages-6.9.1.tar.gz
       fetched from
       ⟨⟩ on
       2024-06-26.  If you discover any rendering problems in this HTML
       version of the page, or you believe there is a better or more up-
       to-date source for the page, or you have corrections or
       improvements to the information in this COLOPHON (which is not
       part of the original manual page), send a mail to

Linux man-pages 6.9.1          2024-05-02                      nextup(3)