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.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
.\" Distributed under GPL
.\" Based on glibc infopages
.TH SIGNBIT 3 2002-08-10 "GNU" "libc math functions"
.SH NAME
signbit \- test sign of a real floating point number
.SH SYNOPSIS
.B "#include <math.h>"
.sp
.BI "int signbit (" X ");"
.sp
Link with \-lm.
.SH DESCRIPTION
`signbit' is a generic macro which can work on all real floating-point
types. It returns a nonzero value if the value of X has its sign
bit set.
.PP
This is not the same as `x < 0.0', because IEEE 754 floating point
allows zero to be signed. The comparison `-0.0 < 0.0' is false,
but `signbit (-0.0)' will return a nonzero value.
.SH "CONFORMING TO"
This function is defined in IEC 559 (and the appendix with
recommended functions in IEEE 754/IEEE 854).
.SH "SEE ALSO"
.BR copysign (3)
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