128 lines
3.1 KiB
Groff
128 lines
3.1 KiB
Groff
.\" Copyright (c) 1985, 1991 Regents of the University of California.
|
|
.\" All rights reserved.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\" 3. All advertising materials mentioning features or use of this software
|
|
.\" must display the following acknowledgement:
|
|
.\" This product includes software developed by the University of
|
|
.\" California, Berkeley and its contributors.
|
|
.\" 4. Neither the name of the University nor the names of its contributors
|
|
.\" may be used to endorse or promote products derived from this software
|
|
.\" without specific prior written permission.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
|
|
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
|
|
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
.\" SUCH DAMAGE.
|
|
.\"
|
|
.\" from: @(#)ieee.3 6.4 (Berkeley) 5/6/91
|
|
.\" $FreeBSD$
|
|
.\"
|
|
.Dd November 6, 2005
|
|
.Dt ILOGB 3
|
|
.Os
|
|
.Sh NAME
|
|
.Nm ilogb ,
|
|
.Nm ilogbf ,
|
|
.Nm ilogbl ,
|
|
.Nm logb ,
|
|
.Nm logbf
|
|
.Nd extract exponent
|
|
.Sh LIBRARY
|
|
.Lb libm
|
|
.Sh SYNOPSIS
|
|
.In math.h
|
|
.Ft int
|
|
.Fn ilogb "double x"
|
|
.Ft int
|
|
.Fn ilogbf "float x"
|
|
.Ft int
|
|
.Fn ilogbl "long double x"
|
|
.Ft double
|
|
.Fn logb "double x"
|
|
.Ft float
|
|
.Fn logbf "float x"
|
|
.Sh DESCRIPTION
|
|
.Fn ilogb ,
|
|
.Fn ilogbf
|
|
and
|
|
.Fn ilogbl
|
|
return
|
|
.Fa x Ns 's exponent
|
|
in integer format.
|
|
.Fn ilogb \*(Pm\*(If
|
|
returns
|
|
.Dv INT_MAX ,
|
|
.Fn ilogb \*(Pm\*(Na
|
|
returns
|
|
.Dv FP_ILOGBNAN ,
|
|
and
|
|
.Fn ilogb 0
|
|
returns
|
|
.Dv FP_ILOGB0 .
|
|
.Pp
|
|
.Fn logb x
|
|
and
|
|
.Fn logbf x
|
|
return
|
|
.Fa x Ns 's exponent
|
|
in floating\-point format with the same precision as
|
|
.Fa x .
|
|
.Fn logb \*(Pm\*(If
|
|
returns +\*(If, and
|
|
.Fn logb 0
|
|
returns -\*(If with a division by zero exception.
|
|
.Sh SEE ALSO
|
|
.Xr frexp 3 ,
|
|
.Xr ieee 3 ,
|
|
.Xr math 3 ,
|
|
.Xr scalbn 3
|
|
.Sh STANDARDS
|
|
The
|
|
.Fn ilogb ,
|
|
.Fn ilogbf ,
|
|
.Fn ilogbl ,
|
|
.Fn logb
|
|
and
|
|
.Fn logbf
|
|
routines conform to
|
|
.St -isoC-99 .
|
|
.Fn logb
|
|
and
|
|
.Fn logbf
|
|
implement the logb function recommended by
|
|
.St -ieee754 .
|
|
.Sh HISTORY
|
|
The
|
|
.Fn logb
|
|
function appeared in
|
|
.Bx 4.3 .
|
|
The
|
|
.Fn ilogb
|
|
function appeared in
|
|
.Fx 1.1.5 .
|
|
The
|
|
.Fn ilogbf
|
|
and
|
|
.Fn logbf
|
|
functions appeared in
|
|
.Fx 2.0 .
|
|
The
|
|
.Fn ilogbl
|
|
function appeared in
|
|
.Fx 5.4 .
|