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[thirdparty/man-pages.git] / man3 / scalbln.3

.\" Copyright 2004 Andries Brouwer <aeb@cwi.nl>.
.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
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.TH SCALBLN 3 2016-03-15 "" "Linux Programmer's Manual"
.SH NAME
scalbn, scalbnf, scalbnl, scalbln, scalblnf, scalblnl \-
multiply floating-point number by integral power of radix
.SH SYNOPSIS
.B #include <math.h>
.PP
.BI "double scalbln(double " x ", long int " exp );
.br
.BI "float scalblnf(float " x ", long int " exp );
.br
.BI "long double scalblnl(long double " x ", long int " exp );
.PP
.BI "double scalbn(double " x ", int " exp );
.br
.BI "float scalbnf(float " x ", int " exp );
.br
.BI "long double scalbnl(long double " x ", int " exp );
.PP
Link with \fI\-lm\fP.
.PP
.in -4n
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.in
.PP
.ad l
.BR scalbln (),
.BR scalblnf (),
.BR scalblnl ():
.RS
_ISOC99_SOURCE || _POSIX_C_SOURCE\ >=\ 200112L
    || /* Since glibc 2.19: */ _DEFAULT_SOURCE
.RE
.br
.BR scalbn (),
.BR scalbnf (),
.BR scalbnl ():
.RS
_ISOC99_SOURCE || _POSIX_C_SOURCE\ >=\ 200112L
    || /* Since glibc 2.19: */ _DEFAULT_SOURCE
    || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
.RE
.ad b
.SH DESCRIPTION
These functions multiply their first argument
.I x
by
.B FLT_RADIX
(probably 2)
to the power of
.IR exp ,
that is:
.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
.IR 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.
.PP
These functions do not set
.IR errno .
.\" FIXME . Is it intentional that these functions do not set errno?
.\" Bug raised: http://sources.redhat.com/bugzilla/show_bug.cgi?id=6803
.SH VERSIONS
These functions first appeared in glibc in version 2.1.
.SH ATTRIBUTES
For an explanation of the terms used in this section, see
.BR attributes (7).
.TS
allbox;
lbw33 lb lb
l l l.
Interface	Attribute	Value
T{
.BR scalbn (),
.BR scalbnf (),
.BR scalbnl (),
.br
.BR scalbln (),
.BR scalblnf (),
.BR scalblnl ()
T}	Thread safety	MT-Safe
.TE
.SH CONFORMING TO
C99, POSIX.1-2001, POSIX.1-2008.
.SH NOTES
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 .
.PP
If
.B FLT_RADIX
equals 2 (which is usual), then
.BR scalbn ()
is equivalent to
.BR ldexp (3).
.SH SEE ALSO
.BR ldexp (3),
.BR scalb (3)