.\" Copyright (c) 2003 Mike Barcroft <mike@FreeBSD.org>
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.\" $FreeBSD: src/lib/msun/man/signbit.3,v 1.1 2004/07/19 08:16:10 das Exp $
.\"
.Dd July 18, 2004
.Dt SIGNBIT 3
.Os
.Sh NAME
.Nm signbit
.Nd "determine whether a floating-point number's sign is negative"
.Sh LIBRARY
.Lb libm
.Sh SYNOPSIS
.In math.h
.Ft int
.Fn signbit "real-floating x"
.Sh DESCRIPTION
The
.Fn signbit
macro takes an argument of
.Fa x
and returns non-zero if the value of its sign is negative, otherwise 0.
.Sh SEE ALSO
.Xr fpclassify 3 ,
.Xr math 3
.Sh STANDARDS
The
.Fn signbit
macro conforms to
.St -isoC-99 .
.Sh HISTORY
The
.Fn signbit
macro was added in
.Fx 5.1 .