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SIGNBIT(3) |
Library Functions Manual |
SIGNBIT(3) |
NAME
signbit — test sign
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <math.h>
int
signbit(real-floating x);
DESCRIPTION
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.
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.
STANDARDS
The signbit() macro conforms to ISO/IEC 9899:1999 (“ISO C99”).