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NEXTAFTER(3) |
Library Functions Manual |
NEXTAFTER(3) |
NAME
nextafter, nextafterf, nextafterl, nexttoward — next representable floating-point number
LIBRARY
Math Library (libm, -lm)
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);
DESCRIPTION
The
nextafter(),
nextafterf(), and
nextafterl() functions return the next machine representable number from
x in direction of
y. In other words, if
y is less than
x, the functions return the largest representable floating-point number less than
x. When
x equals
y, the value of
y is returned. The three functions differ only in the type of the return value and
x.
The nexttoward() function is equivalent to the nextafter() family of functions with two exceptions:
-
The second parameter has a type long double.
-
The return value is y converted to the type of the function, provided that x equals y.
RETURN VALUES
Upon successful completion, the described functions return the next representable floating-point value as described above. If x is finite but an overflow would occur, a range error follows and the functions return ±HUGE_VAL, ±HUGE_VALF, or ±HUGE_VALL with the same sign as x. When either x or y is NaN, a NaN is returned. When x is not y but the function value is subnormal, zero, or underflows, a range error occurs, and either 0.0 or the correct function value (if representable) is returned.
STANDARDS
The described functions conform to ISO/IEC 9899:1999 (“ISO C99”).