diff options
| author | Alejandro Colomar <alx.manpages@gmail.com> | 2022-09-05 23:03:38 +0200 |
|---|---|---|
| committer | Alejandro Colomar <alx.manpages@gmail.com> | 2022-09-05 23:03:47 +0200 |
| commit | 70ac1c4785fc1e158ab2349a962dba2526bf4fbc (patch) | |
| tree | bff270e2496dd284bccfc1271b43946f5d225224 /man/man3/signbit.3 | |
| parent | 5423a6f86b2b920a5f3e8cf8d759b513050f2d33 (diff) | |
| download | man-pages-70ac1c4785fc1e158ab2349a962dba2526bf4fbc.tar.gz | |
src.mk, All pages: Move man* to man/
The root of the repository is becoming a bit overpopulated and
unorganized, due to the recent addition of more mandirs, and more
informative and configuration files too. Let's create a specific
mandir <man/> that contains the mandirs <man[1-8]*>.
Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com>
Diffstat (limited to 'man/man3/signbit.3')
| -rw-r--r-- | man/man3/signbit.3 | 78 |
1 files changed, 78 insertions, 0 deletions
diff --git a/man/man3/signbit.3 b/man/man3/signbit.3 new file mode 100644 index 0000000000..05285e37a9 --- /dev/null +++ b/man/man3/signbit.3 @@ -0,0 +1,78 @@ +.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de) +.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk +.\" <mtk.manpages@gmail.com> +.\" +.\" SPDX-License-Identifier: GPL-1.0-or-later +.\" +.\" Based on glibc infopages, copyright Free Software Foundation +.\" +.TH SIGNBIT 3 2021-03-22 "Linux man-pages (unreleased)" +.SH NAME +signbit \- test sign of a real floating-point number +.SH LIBRARY +Math library +.RI ( libm ", " \-lm ) +.SH SYNOPSIS +.nf +.B "#include <math.h>" +.PP +.BI "int signbit(" x ");" +.fi +.PP +.RS -4 +Feature Test Macro Requirements for glibc (see +.BR feature_test_macros (7)): +.RE +.PP +.BR signbit (): +.nf + _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L +.fi +.SH DESCRIPTION +.BR signbit () +is a generic macro which can work on all real floating-point types. +It returns a nonzero value if the value of +.I x +has its sign bit set. +.PP +This is not the same as +.IR "x < 0.0" , +because IEEE 754 floating point allows zero to be signed. +The comparison +.I \-0.0\~<\~0.0 +is false, but +.I signbit(\-0.0) +will return a nonzero value. +.PP +NaNs and infinities have a sign bit. +.SH RETURN VALUE +The +.BR signbit () +macro returns nonzero if the sign of +.I x +is negative; otherwise it returns zero. +.SH ERRORS +No errors occur. +.SH ATTRIBUTES +For an explanation of the terms used in this section, see +.BR attributes (7). +.ad l +.nh +.TS +allbox; +lbx lb lb +l l l. +Interface Attribute Value +T{ +.BR signbit () +T} Thread safety MT-Safe +.TE +.hy +.ad +.sp 1 +.SH STANDARDS +POSIX.1-2001, POSIX.1-2008, C99. +This function is defined in IEC 559 (and the appendix with +recommended functions in IEEE 754/IEEE 854). +.SH SEE ALSO +.BR copysign (3) |