NEXTAFTER(3) Library Functions Manual NEXTAFTER(3)
nextafter, nextafterf, nextafterl, nexttoward -- next representable
Math Library (libm, -lm)
nextafter(double x, double y);
nextafterf(float x, float y);
nextafterl(long double x, long double y);
nexttoward(double x, long double y);
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:
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.
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
The described functions conform to ISO/IEC 9899:1999 (``ISO C99'').
NetBSD 6.1.5 September 18, 2011 NetBSD 6.1.5