'\" 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 scalb 3 (date) "Linux man-pages (unreleased)"
.SH NAME
scalb, scalbf, scalbl \- multiply floating-point number
by integral power of radix (OBSOLETE)
.SH LIBRARY
Math library
.RI ( libm ", " \-lm )
.SH SYNOPSIS
.nf
.B #include <math.h>
.P
.BI "[[deprecated]] double scalb(double " x ", double " exp );
.BI "[[deprecated]] float scalbf(float " x ", float " exp );
.BI "[[deprecated]] long double scalbl(long double " x ", long double " exp );
.fi
.P
.RS -4
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.RE
.P
.BR scalb ():
.nf
_XOPEN_SOURCE >= 500
.\" || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
.fi
.P
.BR scalbf (),
.BR scalbl ():
.nf
_XOPEN_SOURCE >= 600
|| /* 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:
.P
.nf
x * FLT_RADIX ** exp
.fi
.P
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 .
.P
If
.I x
or
.I exp
is a NaN, a NaN is returned.
.P
If
.I x
is positive infinity (negative infinity),
and
.I exp
is not negative infinity,
positive infinity (negative infinity) is returned.
.P
If
.I x
is +0 (\-0), and
.I exp
is not positive infinity, +0 (\-0) is returned.
.P
If
.I x
is zero, and
.I exp
is positive infinity,
a domain error occurs, and
a NaN is returned.
.P
If
.I x
is an infinity,
and
.I exp
is negative infinity,
a domain error occurs, and
a NaN is returned.
.P
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 .
.P
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.
.P
The following errors can occur:
.TP
Domain error: \fIx\fP is 0, and \fIexp\fP is positive infinity, \
or \fIx\fP is positive infinity and \fIexp\fP is negative infinity \
and the other argument is not a NaN
.I errno
is set to
.BR EDOM .
An invalid floating-point exception
.RB ( FE_INVALID )
is raised.
.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).
.TS
allbox;
lbx lb lb
l l l.
Interface Attribute Value
T{
.na
.nh
.BR scalb (),
.BR scalbf (),
.BR scalbl ()
T} Thread safety MT-Safe
.TE
.SH STANDARDS
None.
.SH HISTORY
.TP
.BR scalb ()
4.3BSD.
Obsolescent in POSIX.1-2001;
Removed in POSIX.1-2008,
recommending the use of
.BR scalbln (3),
.BR scalblnf (3),
or
.BR scalblnl (3)
instead.
.\" Looking at header files: scalbf() is present on the
.\" BSDs, Tru64, HP-UX 11, Irix 6.5; scalbl() is on HP-UX 11 and Tru64.
.SH BUGS
Before glibc 2.20,
.\" https://www.sourceware.org/bugzilla/show_bug.cgi?id=6803
.\" https://www.sourceware.org/bugzilla/show_bug.cgi?id=6804
these functions did not set
.I errno
for domain and range errors.
.SH SEE ALSO
.BR ldexp (3),
.BR scalbln (3)
