mirror of https://github.com/mkerrisk/man-pages
192 lines
4.3 KiB
Groff
192 lines
4.3 KiB
Groff
.\" Copyright 2004 Andries Brouwer <aeb@cwi.nl>.
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.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
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.\" <mtk.manpages@gmail.com>
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.\"
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.\" %%%LICENSE_START(VERBATIM)
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.\" Permission is granted to make and distribute verbatim copies of this
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.\" manual provided the copyright notice and this permission notice are
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.\" preserved on all copies.
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.\"
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.\" Permission is granted to copy and distribute modified versions of this
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.\" manual under the conditions for verbatim copying, provided that the
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.\" entire resulting derived work is distributed under the terms of a
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.\" permission notice identical to this one.
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.\"
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.\" Since the Linux kernel and libraries are constantly changing, this
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.\" manual page may be incorrect or out-of-date. The author(s) assume no
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.\" responsibility for errors or omissions, or for damages resulting from
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.\" the use of the information contained herein. The author(s) may not
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.\" have taken the same level of care in the production of this manual,
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.\" which is licensed free of charge, as they might when working
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.\" professionally.
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.\"
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.\" the source, must acknowledge the copyright and authors of this work.
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.\" %%%LICENSE_END
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.\"
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.TH SCALBLN 3 2013-06-21 "" "Linux Programmer's Manual"
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.SH NAME
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scalbn, scalbnf, scalbnl, scalbln, scalblnf, scalblnl \-
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multiply floating-point number by integral power of radix
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.SH SYNOPSIS
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.B #include <math.h>
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.sp
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.BI "double scalbln(double " x ", long int " exp );
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.br
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.BI "float scalblnf(float " x ", long int " exp );
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.br
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.BI "long double scalblnl(long double " x ", long int " exp );
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.sp
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.BI "double scalbn(double " x ", int " exp );
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.br
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.BI "float scalbnf(float " x ", int " exp );
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.br
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.BI "long double scalbnl(long double " x ", int " exp );
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.sp
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Link with \fI\-lm\fP.
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.sp
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.in -4n
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Feature Test Macro Requirements for glibc (see
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.BR feature_test_macros (7)):
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.in
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.sp
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.ad l
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.BR scalbln (),
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.BR scalblnf (),
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.BR scalblnl ():
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.RS
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_XOPEN_SOURCE\ >=\ 600 || _ISOC99_SOURCE ||
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_POSIX_C_SOURCE\ >=\ 200112L;
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.br
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or
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.I cc\ -std=c99
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.RE
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.br
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.BR scalbn (),
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.BR scalbnf (),
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.BR scalbnl ():
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.RS
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_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE\ >=\ 600 || _ISOC99_SOURCE ||
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_POSIX_C_SOURCE\ >=\ 200112L;
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.br
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or
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.I cc\ -std=c99
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.RE
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.ad b
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.SH DESCRIPTION
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These functions multiply their first argument
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.I x
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by
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.B FLT_RADIX
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(probably 2)
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to the power of
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.IR exp ,
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that is:
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.nf
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x * FLT_RADIX ** exp
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.fi
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The definition of
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.B FLT_RADIX
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can be obtained by including
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.IR <float.h> .
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.\" not in /usr/include but in a gcc lib
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.SH RETURN VALUE
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On success, these functions return
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.IR x
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*
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.B FLT_RADIX
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**
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.IR exp .
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If
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.I x
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is a NaN, a NaN is returned.
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If
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.I x
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is positive infinity (negative infinity),
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positive infinity (negative infinity) is returned.
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If
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.I x
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is +0 (\-0), +0 (\-0) is returned.
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If the result overflows,
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a range error occurs,
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and the functions return
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.BR HUGE_VAL ,
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.BR HUGE_VALF ,
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or
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.BR HUGE_VALL ,
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respectively, with a sign the same as
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.IR x .
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If the result underflows,
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a range error occurs,
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and the functions return zero, with a sign the same as
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.IR x .
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.SH ERRORS
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See
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.BR math_error (7)
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for information on how to determine whether an error has occurred
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when calling these functions.
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.PP
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The following errors can occur:
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.TP
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Range error, overflow
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.\" .I errno
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.\" is set to
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.\" .BR ERANGE .
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An overflow floating-point exception
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.RB ( FE_OVERFLOW )
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is raised.
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.TP
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Range error, underflow
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.\" .I errno
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.\" is set to
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.\" .BR ERANGE .
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An underflow floating-point exception
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.RB ( FE_UNDERFLOW )
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is raised.
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.PP
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These functions do not set
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.IR errno .
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.\" FIXME . Is it intentional that these functions do not set errno?
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.\" Bug raised: http://sources.redhat.com/bugzilla/show_bug.cgi?id=6803
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.SH VERSIONS
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These functions first appeared in glibc in version 2.1.
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.SH ATTRIBUTES
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.SS Multithreading (see pthreads(7))
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The
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.BR scalbn (),
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.BR scalbnf (),
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.BR scalbnl (),
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.BR scalbln (),
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.BR scalblnf (),
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and
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.BR scalblnl ()
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functions are thread-safe.
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.SH CONFORMING TO
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C99, POSIX.1-2001.
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.SH NOTES
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These functions differ from the obsolete functions described in
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.BR scalb (3)
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in the type of their second argument.
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The functions described on this page have a second argument
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of an integral type, while those in
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.BR scalb (3)
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have a second argument of type
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.IR double .
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If
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.B FLT_RADIX
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equals 2 (which is usual), then
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.BR scalbn ()
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is equivalent to
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.BR ldexp (3).
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.SH SEE ALSO
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.BR ldexp (3),
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.BR scalb (3)
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