signbit(3) - NetBSD Manual Pages

SIGNBIT(3)              NetBSD 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.


SEE ALSO

     fpclassify(3), isfinite(3), isnormal(3), math(3)


STANDARDS

     The signbit() macro conforms to ISO/IEC 9899:1999 (``ISO C99'').

NetBSD 10.99                   October 29, 2003                   NetBSD 10.99