NEXTAFTER(3)

NEXTAFTER(3) | Library Functions Manual | NEXTAFTER(3)

# NAME

`nextafter`, `nextafterf`, `nextafterl`, `nexttoward`, `nexttowardf`, `nexttowardl` —
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);

float
`nexttowardf`(float x, long double y);

long double
`nexttowardl`(long 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`() and `nexttowardf`() functions are equivalent to the `nextafter`() family of functions with two exceptions:

1. The second parameter has a type long double.
2. The return value is y converted to the type of the function, provided that x equals y.

`nexttowardl`() is equivalent to `nextafterl`().

# 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.

# SEE ALSO

math(3)

# STANDARDS

The described functions conform to ISO/IEC 9899:1999 (“ISO C99”).

September 13, 2015 | NetBSD 10.0