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);Link with -lm.
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 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.
See DESCRIPTION.