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SIGNBIT(3)                 Linux Programmer's Manual                SIGNBIT(3)



NAME
       signbit - test sign of a real floating point number

SYNOPSIS
       #include <&lt;math.h>&gt;

       int signbit(x);

       Compile with -std=c99; link with -lm.

DESCRIPTION
       signbit()  is a generic macro which can work on all real floating-point
       types.  It returns a non-zero value if the value of x has its sign  bit
       set.

       This is not the same as x &lt; 0.0, because IEEE 754 floating point allows
       zero to be signed.  The comparison -0.0  &lt;  0.0  is  false,  but  sign-
       bit(-0.0) will return a non-zero value.

CONFORMING TO
       C99.  This function is defined in IEC 559 (and the appendix with recom-
       mended functions in IEEE 754/IEEE 854).

SEE ALSO
       copysign(3)

COLOPHON
       This page is part of release 3.05 of the Linux  man-pages  project.   A
       description  of  the project, and information about reporting bugs, can
       be found at http://www.kernel.org/doc/man-pages/.



GNU                               2002-08-10                        SIGNBIT(3)