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signbit(3M)

HP-UX 11i Version 3: February 2007
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NAME

signbit() — floating-point sign-determination

SYNOPSIS

#include <math.h>

int signbit( floating-type x);

DESCRIPTION

The signbit() macro determines whether the sign of its argument value (which may be a floating-point number, zero, infinity, or NaN) is negative. The argument must be of floating type. For HP Integrity servers, the argument can be any floating type. For PA-RISC, the argument must be either double or float.

USAGE

To use the signbit() macro, compile either with the default -Ae option or with the -Aa and -D_HPUX_SOURCE options. Make sure your program includes <math.h>. Link in the math library by specifying -lm on the compiler or linker command line.

RETURN VALUE

The signbit() macro returns a nonzero value if and only if the sign of its argument value is negative.

The macro raises no exceptions.

ERRORS

No errors are defined.

EXAMPLES

Take certain actions if x is negative zero:

#include <math.h> /*...*/ double x; /*...*/ if ( (x == 0.0) && signbit(x) ) { /*...*/ }

STANDARDS CONFORMANCE

signbit() : ISO/IEC C99 (including Annex F, ``IEC 60559 floating-point arithmetic'')

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