xref: /netbsd-src/lib/libm/man/ldexp.3 (revision 71f379ad51f72c27767914fabec980e2408fdefa)

.\"	$NetBSD: ldexp.3,v 1.5 2016/03/17 18:29:59 nros Exp $
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.\"     @(#)ldexp.3	8.2 (Berkeley) 4/19/94
.\"
.Dd March 17, 2016
.Dt LDEXP 3
.Os
.Sh NAME
.Nm ldexp ,
.Nm ldexpf ,
.Nm ldexpl
.Nd multiply floating-point number by integral power of 2
.Sh LIBRARY
.Lb libm
.Sh SYNOPSIS
.In math.h
.Ft double
.Fn ldexp "double x" "int exp"
.Ft float
.Fn ldexpf "float x" "int exp"
.Ft long double
.Fn ldexpl "long double x" "int exp"
.Sh DESCRIPTION
The
.Fn ldexp
family of functions compute
.Bd -ragged -offset indent
.Va x
*
2^\fIexp\fR
.Ed
.Pp
for a real floating-point number
.Fa x .
.Sh RETURN VALUES
The functions return the value of
.Fa x
times 2 raised to the power
.Fa exp .
Otherwise the following may occur:
.Bl -enum -offset indent
.It
If
.Fa x
is \*(Na, a \*(Na is returned.
.It
If
.Fa exp
is zero or
.Fa x
is either \*(Pm 0 or \*(Pm\[if],
.Fa x
is returned.
.It
If the call would cause an overflow, a range error occurs and either
.Dv \*(Pm\*HHUGE_VAL ,
.Dv  \*(Pm\*HHUGE_VALF ,
or
.Dv  \*(Pm\*HHUGE_VALL
is returned, depending on the sign of
.Fa x
and the type of the return value.
.It
If an underflow would be caused by the correct value,
and the value is not representable, either 0.0 or
an implementation-defined value is returned.
.El
.Sh SEE ALSO
.Xr frexp 3 ,
.Xr math 3 ,
.Xr modf 3
.Sh STANDARDS
The described functions conform to
.St -isoC-99 .