NAME
nextafter,
nextafterf, nextafterl,
nexttoward, nexttowardf
— next representable
floating-point number
LIBRARY
library “libm”
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);
DESCRIPTION
Thenextafter(),
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:
- 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.
SEE ALSO
STANDARDS
The described functions conform to ISO/IEC 9899:1999 (“ISO C99”).