LDP: Update original to LDP v3.79

[linuxjm/LDP_man-pages.git] / original / man3 / pow.3

diff --git a/original/man3/pow.3 b/original/man3/pow.3
index dad07b7..8e73965 100644 (file)
--- a/original/man3/pow.3
+++ b/original/man3/pow.3
@@ -2,6 +2,7 @@
 .\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
 .\"     <mtk.manpages@gmail.com>
 .\"
+.\" %%%LICENSE_START(VERBATIM)
 .\" Permission is granted to make and distribute verbatim copies of this
 .\" manual provided the copyright notice and this permission notice are
 .\" preserved on all copies.
@@ -21,6 +22,7 @@
 .\"
 .\" Formatted or processed versions of this manual, if unaccompanied by
 .\" the source, must acknowledge the copyright and authors of this work.
+.\" %%%LICENSE_END
 .\"
 .\" References consulted:
 .\"     Linux libc source code
@@ -30,7 +32,7 @@
 .\" Modified 1995-08-14 by Arnt Gulbrandsen <agulbra@troll.no>
 .\" Modified 2002-07-27 by Walter Harms
 .\"    (walter.harms@informatik.uni-oldenburg.de)
-.TH POW 3  2008-08-10 "" "Linux Programmer's Manual"
+.TH POW 3  2014-12-31 "" "Linux Programmer's Manual"
 .SH NAME
 pow, powf, powl \- power functions
 .SH SYNOPSIS
@@ -54,14 +56,22 @@ Feature Test Macro Requirements for glibc (see
 .ad l
 .BR powf (),
 .BR powl ():
-_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE\ >=\ 600 || _ISOC99_SOURCE; or
+.RS 4
+_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE\ >=\ 600 || _ISOC99_SOURCE ||
+_POSIX_C_SOURCE\ >=\ 200112L;
+.br
+or
 .I cc\ -std=c99
-.ad b
+.RE
+.ad
 .SH DESCRIPTION
 The
 .BR pow ()
-function returns the value of \fIx\fP raised to the
-power of \fIy\fP.
+function returns the value of
+.I x
+raised to the
+power of
+.IR y .
 .SH RETURN VALUE
 On success, these functions return the value of
 .I x
@@ -217,7 +227,7 @@ the result is positive infinity.
 
 If
 .I x
-is +0 or -0,
+is +0 or \-0,
 and
 .I y
 is an odd integer less than 0,
@@ -232,7 +242,7 @@ with the same sign as
 
 If
 .I x
-is +0 or -0,
+is +0 or \-0,
 and
 .I y
 is less than 0 and not an odd integer,
@@ -284,7 +294,6 @@ Pole error: \fIx\fP is zero, and \fIy\fP is negative
 is set to
 .BR ERANGE
 (but see BUGS).
-.\" FIXME . glibc 2.8 gives EDOM
 A divide-by-zero floating-point exception
 .RB ( FE_DIVBYZERO )
 is raised.
@@ -304,22 +313,39 @@ is set to
 An underflow floating-point exception
 .RB ( FE_UNDERFLOW )
 is raised.
-.SH "CONFORMING TO"
+.SH CONFORMING TO
 C99, POSIX.1-2001.
 The variant returning
 .I double
 also conforms to
 SVr4, 4.3BSD, C89.
 .SH BUGS
-For a pole error,
+On 64-bits,
+.\"
+.\" https://sourceware.org/bugzilla/show_bug.cgi?id=13932
+.BR pow ()
+may be more than 10,000 times slower for some (rare) inputs
+than for other nearby inputs.
+This affects only
+.BR pow (),
+and not
+.BR powf ()
+nor
+.BR powl ().
+
+In glibc 2.9 and earlier,
 .\"
-.\" FIXME . this is as at glibc 2.8; check later if this bug is fixed
-.\" Bug raised: http://sources.redhat.com/bugzilla/show_bug.cgi?id=6776
+.\" http://sources.redhat.com/bugzilla/show_bug.cgi?id=6776
+when a pole error occurs,
 .I errno
 is set to
-.BR EDOM ;
-POSIX.1 says it should be set to
+.BR EDOM
+instead of the POSIX-mandated
 .BR ERANGE .
+Since version 2.10,
+.\" or possibly 2.9, I haven't found the source code change
+.\" and I don't have a 2.9 system to test
+glibc does the right thing.
 
 If
 .I x
@@ -349,7 +375,16 @@ when an overflow or underflow error occurs, glibc's
 generates a bogus invalid floating-point exception
 .RB ( FE_INVALID )
 in addition to the overflow or underflow exception.
-.SH "SEE ALSO"
+.SH SEE ALSO
 .BR cbrt (3),
 .BR cpow (3),
 .BR sqrt (3)
+.SH COLOPHON
+This page is part of release 3.79 of the Linux
+.I man-pages
+project.
+A description of the project,
+information about reporting bugs,
+and the latest version of this page,
+can be found at
+\%http://www.kernel.org/doc/man\-pages/.