[thirdparty/man-pages.git] / man3 / signbit.3

.\" 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
Compile with -std=c99; link with \-lm.
.SH 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.
.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 non-zero 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)
Commit	Line	Data
fea681da MK	1	.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
	2	.\" Distributed under GPL
	3	.\" Based on glibc infopages
	4	.TH SIGNBIT 3 2002-08-10 "GNU" "libc math functions"
	5	.SH NAME
	6	signbit \- test sign of a real floating point number
	7	.SH SYNOPSIS
	8	.B "#include <math.h>"
	9	.sp
	10	.BI "int signbit (" X ");"
	11	.sp
462a7bad	12	Compile with -std=c99; link with \-lm.
fea681da MK	13	.SH DESCRIPTION
fea681da MK	14	`signbit' is a generic macro which can work on all real floating-point
f59a3f19	15	types. It returns a non-zero value if the value of X has its sign
fea681da MK	16	bit set.
	17	.PP
	18	This is not the same as `x < 0.0', because IEEE 754 floating point
	19	allows zero to be signed. The comparison `-0.0 < 0.0' is false,
f59a3f19	20	but `signbit (-0.0)' will return a non-zero value.
fea681da MK	21	.SH "CONFORMING TO"
	22	This function is defined in IEC 559 (and the appendix with
	23	recommended functions in IEEE 754/IEEE 854).
	24	.SH "SEE ALSO"
	25	.BR copysign (3)