path: root/usr/src/man/man3m/scalb.3m

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.\" Portions Copyright 2019 Garrett D'Amore <garrett@damore.org>
.Dd Jul 05, 2019
.Dt SCALB 3M
.Os
.Sh NAME
.Nm scalb ,
.Nm scalbf ,
.Nm scalbl
.Nd load exponent of a radix-independent floating-point number
.Sh SYNOPSIS
.Ic c99 Oo Ar flag Ns ... Oc Ar file Ns ... Fl lm Op Ar library Ns ...
.Pp
.In math.h
.
.Ft double
.Fo scalb
.Fa "double x"
.Fa "double n"
.Fc
.
.Ft float
.Fo scalbf
.Fa "float x"
.Fa "float n"
.Fc
.
.Ft "long double"
.Fo scalbl
.Fa "long double x"
.Fa "long double n"
.Fc
.
.Sh DESCRIPTION
These functions compute
.Fa x No * Va r Ns No ^ Ns Fa n ,
where
.Va r
is the radix of the machine's floating point arithmetic.
When
.Va r
is 2,
.Fn scalb
is equivalent to
.Xr ldexp 3M .
The value of
.Va r
is
.Dv FLT_RADIX
which is
defined in
.In float.h .
.Sh RETURN VALUES
Upon successful completion, the
.Fn scalb
function returns
.Fa x No * Va r Ns No ^ Ns Fa n .
.Pp
If
.Fa x
or
.Fa n
is
.Sy NaN ,
a
.Sy NaN
is returned.
.Lp
If
.Fa n
is 0,
.Fa x
is returned.
.Lp
If
.Fa x
is
.Sy \(+-Inf
and
.Fa n
is not
.Sy \(miInf ,
.Fa x
is returned.
.Lp
If
.Fa x
is \(+-0 and
.Fa n
is not
.Sy +Inf ,
.Fa x
is returned.
.Lp
If
.Fa x
is \(+-0 and
.Fa n
is
.Sy +Inf ,
a domain error occurs and a
.Sy NaN
is returned.
.Lp
If
.Fa x
is
.Sy \(+-Inf
and
Fa n
is
.Sy \(miInf ,
a domain error occurs and a
.Sy NaN
is returned.
.Lp
If the result would cause an overflow, a range error occurs and
.Dv \(+-HUGE_VAL
(according to the sign of
.Fa x )
is returned.
.Lp
For exceptional cases,
.Xr matherr 3M
tabulates the values to be returned by
.Fn scalb
as specified by SVID3 and XPG3.
See
.Xr standards 7 .
.
.Sh ERRORS
.
These functions will fail if:
.
.Bl -tag -width Sy
.It Sy Domain Error
If
.Fa x
is 0 and
.Fa n
is
.Sy +Inf ,
or
.Fa x
is
.Sy Inf
and
.Fa n
is
.Sy \(miInf .
.Lp
If the integer expression
.Po Va math_errhandling No & Dv MATH_ERREXCEPT Pc
.\" (\fBmath_errhandling\fR & \fBMATH_ERREXCEPT\fR)
is non-zero, then the invalid floating-point exception is raised.
.
.It Sy Range Error
The result would overflow.
.Lp
If the integer expression
.Po Va math_errhandling No & Dv MATH_ERREXCEPT Pc
is non-zero, then the overflow floating-point exception is raised.
.El
.
.Sh USAGE
An application wanting to check for exceptions should call
.Fn feclearexcept FE_ALL_EXCEPT
before calling these functions.
On return, if
.Fn fetestexcept "FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW"
is non-zero, an exception has been raised.
An application should either examine the return value or check the
floating point exception flags to detect exceptions.
.
.Lp
.
These functions are
.Sy Obsolete .
The
.Xr scalbln 3M ,
.Xr scalblnf 3M ,
or
.Xr scalblnl 3M
functions should be used instead.
.
.Sh MT-LEVEL
.
.Sy MT-Safe .
.
.Sh INTERFACE STABILITY
.
The
.Fn scalb
function is
.Sy Obsolete Standard .
The
.Fn scalbf
and
.Fn scalbl
functions are
.Sy Obsolete Committed .
.
.Sh SEE ALSO
.
.Xr math.h 3HEAD ,
.Xr feclearexcept 3M ,
.Xr fetestexcept 3M ,
.Xr ilogb 3M ,
.Xr ldexp 3M ,
.Xr logb 3M ,
.Xr matherr 3M ,
.Xr scalbln 3M ,
.Xr attributes 7 ,
.Xr standards 7