NAME

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

LIBRARY

       Math library (libm, -lm)

SYNOPSIS

       #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

       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 or -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.

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 │
       └─────────────────────────────────────────────────────────────────────────────┴───────────────┴─────────┘

STANDARDS

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

HISTORY

       glibc 2.24.

SEE ALSO

       nearbyint(3), nextafter(3)

Linux man-pages 6.16                               2025-05-17                                          nextup(3)