NetBSD/lib/libc/gen/ldexp.3

.\"	$NetBSD: ldexp.3,v 1.9 2002/02/07 07:00:15 ross Exp $
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.\"     @(#)ldexp.3	8.2 (Berkeley) 4/19/94
.\"
.Dd August 29, 1999
.Dt LDEXP 3
.Os
.Sh NAME
.Nm ldexp
.Nd multiply floating-point number by integral power of 2
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.Fd #include \*[Lt]math.h\*[Gt]
.Ft double
.Fn ldexp "double x" "int exp"
.Sh DESCRIPTION
The
.Fn ldexp
function multiplies a floating-point number by an integral
power of 2.
.Sh RETURN VALUES
The
.Fn ldexp
function returns the value of
.Fa x
times 2 raised to the power
.Fa exp .
.Pp
If the input
.Va x
is a NaN, infinity, or 0.0, it is returned unchanged.
.Pp
If the result would cause an overflow,
the global variable
.Va errno
is set to
.Er ERANGE
and infinity is returned, with the same sign as
.Fa x .
.Pp
If the result would cause underflow to 0.0,
the global variable
.Va errno
is set to
.Er ERANGE
and the value 0.0 is returned.
.Sh SEE ALSO
.Xr frexp 3 ,
.Xr math 3 ,
.Xr modf 3
.Sh STANDARDS
The
.Fn ldexp
function conforms to
.St -ansiC .