'\" t
.\" Copyright 2004 Andries Brouwer <aeb@cwi.nl>.
.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
.\"     <mtk.manpages@gmail.com>
.\"
.\" SPDX-License-Identifier: Linux-man-pages-copyleft
.\"
.TH scalbln 3 2023-03-30 "Linux man-pages 6.04"
.SH NAME
scalbn, scalbnf, scalbnl, scalbln, scalblnf, scalblnl \-
multiply floating-point number by integral power of radix
.SH LIBRARY
Math library
.RI ( libm ", " \-lm )
.SH SYNOPSIS
.nf
.B #include <math.h>
.PP
.BI "double scalbln(double " x ", long " exp );
.BI "float scalblnf(float " x ", long " exp );
.BI "long double scalblnl(long double " x ", long " exp );
.PP
.BI "double scalbn(double " x ", int " exp );
.BI "float scalbnf(float " x ", int " exp );
.BI "long double scalbnl(long double " x ", int " exp );
.fi
.PP
.RS -4
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.RE
.PP
.BR scalbln (),
.BR scalblnf (),
.BR scalblnl ():
.nf
    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
.fi
.PP
.BR scalbn (),
.BR scalbnf (),
.BR scalbnl ():
.nf
    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
.fi
.SH DESCRIPTION
These functions multiply their first argument
.I x
by
.B FLT_RADIX
(probably 2)
to the power of
.IR exp ,
that is:
.PP
.nf
    x * FLT_RADIX ** exp
.fi
.PP
The definition of
.B FLT_RADIX
can be obtained by including
.IR <float.h> .
.\" not in /usr/include but in a gcc lib
.SH RETURN VALUE
On success, these functions return
.I x
*
.B FLT_RADIX
**
.IR exp .
.PP
If
.I x
is a NaN, a NaN is returned.
.PP
If
.I x
is positive infinity (negative infinity),
positive infinity (negative infinity) is returned.
.PP
If
.I x
is +0 (\-0), +0 (\-0) is returned.
.PP
If the result overflows,
a range error occurs,
and the functions return
.BR HUGE_VAL ,
.BR HUGE_VALF ,
or
.BR HUGE_VALL ,
respectively, with a sign the same as
.IR x .
.PP
If the result underflows,
a range error occurs,
and the functions return zero, with a sign the same as
.IR x .
.SH ERRORS
See
.BR math_error (7)
for information on how to determine whether an error has occurred
when calling these functions.
.PP
The following errors can occur:
.TP
Range error, overflow
.\" .I errno
.\" is set to
.\" .BR ERANGE .
An overflow floating-point exception
.RB ( FE_OVERFLOW )
is raised.
.TP
Range error, underflow
.I errno
is set to
.BR ERANGE .
An underflow floating-point exception
.RB ( FE_UNDERFLOW )
is raised.
.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 scalbn (),
.BR scalbnf (),
.BR scalbnl (),
.BR scalbln (),
.BR scalblnf (),
.BR scalblnl ()
T}	Thread safety	MT-Safe
.TE
.hy
.ad
.sp 1
.SH STANDARDS
C11, POSIX.1-2008.
.SH HISTORY
glibc 2.1.
C99, POSIX.1-2001.
.SH HISTORY
These functions differ from the obsolete functions described in
.BR scalb (3)
in the type of their second argument.
The functions described on this page have a second argument
of an integral type, while those in
.BR scalb (3)
have a second argument of type
.IR double .
.SH NOTES
If
.B FLT_RADIX
equals 2 (which is usual), then
.BR scalbn ()
is equivalent to
.BR ldexp (3).
.SH BUGS
Before glibc 2.20,
.\" https://www.sourceware.org/bugzilla/show_bug.cgi?id=6803
these functions did not set
.I errno
for range errors.
.SH SEE ALSO
.BR ldexp (3),
.BR scalb (3)