NAME
signbit —
test sign
LIBRARY
library “libc”
SYNOPSIS
#include
<math.h>
int
signbit(real-floating
x);
DESCRIPTION
Thesignbit()
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.
IEEE754
The sign is determined for all values, including infinities, zeroes, and NaNs
VAX
The sign is determined for finites, true zeros, and dirty zeroes; for ROPs the sign is reported negative.
RETURN VALUES
The signbit() macro returns a non-zero
value if the sign of its value x is negative.
Otherwise 0 is returned.
ERRORS
No errors are defined.
SEE ALSO
STANDARDS
The signbit() macro conforms to
ISO/IEC 9899:1999
(“ISO C99”).