nextup, nextupf, nextupl, nextdown, nextdownf, nextdownl - return next floating-point number toward positive/negative infinity
#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);
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.
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.
x is Nan, the returned value is NaN.
The value returned by
-nextup(-x), and similarly for the other types.
These functions first appeared in glibc in version 2.24.
These functions are described in
IEEE Std 754-2008 - Standard for Floating-Point Arithmetic and
ISO/IEC TS 18661.
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