dlopen.3: Clarify that constructors are called only when library is first loaded

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

diff --git a/man3/signbit.3 b/man3/signbit.3
index 428dd4eaa912a8147329a874145dfe5e11832ebd..819ef64c68c94d4d09cbc1738f216187649ca150 100644 (file)
--- a/man3/signbit.3
+++ b/man3/signbit.3
@@ -1,25 +1,74 @@
 .\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" %%%LICENSE_START(GPL_NOVERSION_ONELINE)
 .\" Distributed under GPL
-.\" Based on glibc infopages
-.TH SIGNBIT 3 2002-08-10 "GNU" "libc math functions"
+.\" %%%LICENSE_END
+.\"
+.\" Based on glibc infopages, copyright Free Software Foundation
+.\"
+.TH SIGNBIT 3 2017-09-15 "GNU" "Linux Programmer's Manual"
 .SH NAME
-signbit \- test sign of a real floating point number
+signbit \- test sign of a real floating-point number
 .SH SYNOPSIS
 .B "#include <math.h>"
-.sp
-.BI  "int signbit (" X ");"
-.sp
-Link with \-lm.
+.PP
+.BI  "int signbit(" x ");"
+.PP
+Link with \fI\-lm\fP.
+.PP
+.in -4n
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.in
+.PP
+.ad l
+.BR signbit ():
+.RS 4
+_ISOC99_SOURCE || _POSIX_C_SOURCE\ >=\ 200112L
+.RE
+.ad
 .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.
+.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
+.IR "\-0.0 < 0.0"
+is false, but
+.IR "signbit(\-0.0)"
+will return a nonzero value.
 .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"
+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).
+.TS
+allbox;
+lb lb lb
+l l l.
+Interface      Attribute       Value
+T{
+.BR signbit ()
+T}     Thread safety   MT-Safe
+.TE
+.SH CONFORMING TO
+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"
+.SH SEE ALSO
 .BR copysign (3)