SIGNBIT(3) BSD Programmer's Manual SIGNBIT(3)
signbit - test sign
libc
#include <math.h>
int
signbit(real-floating x);
The signbit() macro determines whether the sign of its argument value x
is negative. An argument represented in a format wider than its semantic
type is converted to its semantic type first. The determination is then
based on the type of the argument.
The sign is determined for all values, including infinities, zeroes, and
NaNs
The sign is determined for finites, true zeros, and dirty zeroes; for
ROPs the sign is reported negative.
The signbit() macro returns a non-zero value if the sign of its value x
is negative. Otherwise 0 is returned.
No errors are defined.
fpclassify(3), isfinite(3), isnormal(3), math(3)
The signbit() macro conforms to ISO/IEC 9899:1999 ("ISO C99").
MirBSD #10-current October 29, 2003 1