mirror of https://github.com/mkerrisk/man-pages
221 lines
4.9 KiB
Groff
221 lines
4.9 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.\" manual page may be incorrect or out-of-date.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 SCALB 3 2016-03-15 "" "Linux Programmer's Manual"
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.SH NAME
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scalb, scalbf, scalbl \- multiply floating-point number
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by integral power of radix (OBSOLETE)
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.SH SYNOPSIS
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.B #include <math.h>
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.PP
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.BI "double scalb(double " x ", double " exp );
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.br
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.BI "float scalbf(float " x ", float " exp );
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.br
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.BI "long double scalbl(long double " x ", long double " exp );
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.PP
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Link with \fI\-lm\fP.
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.PP
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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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.PP
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.ad l
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.BR scalb ():
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.RS 4
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_XOPEN_SOURCE\ >=\ 500
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.\" || _XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED
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|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
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|| /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
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.RE
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.br
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.BR scalbf (),
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.BR scalbl ():
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.RS 4
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_XOPEN_SOURCE\ >=\ 600
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|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
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|| /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
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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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.PP
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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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.PP
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If
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.I x
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or
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.I exp
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is a NaN, a NaN is returned.
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.PP
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If
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.I x
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is positive infinity (negative infinity),
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and
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.I exp
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is not negative infinity,
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positive infinity (negative infinity) is returned.
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.PP
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If
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.I x
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is +0 (\-0), and
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.I exp
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is not positive infinity, +0 (\-0) is returned.
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.PP
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If
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.I x
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is zero, and
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.I exp
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is positive infinity,
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a domain error occurs, and
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a NaN is returned.
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.PP
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If
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.I x
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is an infinity,
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and
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.I exp
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is negative infinity,
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a domain error occurs, and
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a NaN is returned.
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.PP
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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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.PP
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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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Domain error: \fIx\fP is 0, and \fIexp\fP is positive infinity, \
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or \fIx\fP is positive infinity and \fIexp\fP is negative infinity \
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and the other argument is not a NaN
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.\" .I errno
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.\" is set to
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.\" .BR EDOM .
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An invalid floating-point exception
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.RB ( FE_INVALID )
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is raised.
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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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.\" Bug raised: http://sources.redhat.com/bugzilla/show_bug.cgi?id=6804
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.SH ATTRIBUTES
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For an explanation of the terms used in this section, see
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.BR attributes (7).
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.TS
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allbox;
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lbw28 lb lb
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l l l.
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Interface Attribute Value
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T{
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.BR scalb (),
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.BR scalbf (),
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.BR scalbl ()
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T} Thread safety MT-Safe
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.TE
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.SH CONFORMING TO
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.BR scalb ()
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is specified in POSIX.1-2001, but marked obsolescent.
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POSIX.1-2008 removes the specification of
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.BR scalb (),
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recommending the use of
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.BR scalbln (3),
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.BR scalblnf (3),
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or
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.BR scalblnl (3)
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instead.
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The
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.BR scalb ()
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function is from 4.3BSD.
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.PP
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.BR scalbf ()
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and
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.BR scalbl ()
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are unstandardized;
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.BR scalbf ()
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is nevertheless present on several other systems
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.\" Looking at header files: scalbf() is present on the
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.\" BSDs, Tru64, HP-UX 11, Irix 6.5; scalbl() is on HP-UX 11 and Tru64.
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.SH SEE ALSO
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.BR ldexp (3),
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.BR scalbln (3)
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