190 lines
4.1 KiB
Groff
190 lines
4.1 KiB
Groff
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.\" Copyright (c) 1985, 1991 Regents of the University of California.
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" from: @(#)ieee.3 6.4 (Berkeley) 5/6/91
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.\" $NetBSD: ieee.3,v 1.21 2010/09/15 16:11:30 christos Exp $
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.\"
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.Dd February 25, 1994
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.Dt IEEE 3
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.Os
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.Sh NAME
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.Nm copysign ,
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.Nm copysignf ,
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.Nm copysignl ,
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.Nm finite ,
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.Nm finitef ,
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.Nm ilogb ,
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.Nm ilogbf ,
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.Nm nextafter ,
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.Nm nextafterf ,
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.Nm nextafterl ,
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.Nm nexttoward ,
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.Nm remainder ,
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.Nm remainderf ,
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.Nm scalbn ,
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.Nm scalbnf
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.Nd functions for IEEE arithmetic
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.Sh LIBRARY
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.Lb libm
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.Sh SYNOPSIS
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.In math.h
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.Ft double
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.Fn copysign "double x" "double y"
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.Ft float
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.Fn copysignf "float x" "float y"
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.Ft long double
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.Fn copysignl "long double x" "long double y"
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.Ft int
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.Fn finite "double x"
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.Ft int
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.Fn finitef "float x"
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.Ft int
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.Fn ilogb "double x"
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.Ft int
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.Fn ilogbf "float x"
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.Ft double
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.Fn nextafter "double x" "double y"
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.Ft float
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.Fn nextafterf "float x" "float y"
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.Ft long double
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.Fn nextafterl "long double x" "long double y"
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.Ft double
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.Fn nexttoward "double x" "long double y"
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.Ft double
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.Fn remainder "double x" "double y"
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.Ft float
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.Fn remainderf "float x" "float y"
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.Ft double
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.Fn scalbn "double x" "int n"
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.Ft float
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.Fn scalbnf "float x" "int n"
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.Sh DESCRIPTION
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These functions are required or recommended by
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.St -ieee754 .
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.Pp
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.Fn copysign
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returns
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.Fa x
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with its sign changed to
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.Fa y Ns 's .
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.Pp
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.Fn finite
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returns the value 1 just when
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\-\*(If \*(Lt
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.Fa x
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\*(Lt +\*(If;
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otherwise a
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zero is returned
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(when
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.Pf \*(Ba Ns Fa x Ns \*(Ba
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= \*(If or
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.Fa x
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is \*(Na).
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.Pp
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.Fn ilogb
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returns
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.Fa x Ns 's exponent
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.Fa n ,
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in integer format.
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.Fn ilogb \*(Pm\*(If
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returns
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.Dv INT_MAX
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and
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.Fn ilogb 0
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returns
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.Dv INT_MIN .
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.Pp
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.Fn nextafter
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returns the next machine representable number from
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.Fa x
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in direction
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.Fa y .
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.Pp
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.Fn nexttoward
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is equivalent to
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.Fn nextafter ,
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except that the second parameter has type
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.Ft long double
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and the function returns
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.Dv y
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converted to the type of the function if
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.Dv x
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equals
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.Dv y .
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.Pp
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.Fn remainder
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returns the remainder
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.Fa r
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:=
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.Fa x
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\-
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.Fa n\(**y
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where
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.Fa n
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is the integer nearest the exact value of
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.Bk -words
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.Fa x Ns / Ns Fa y ;
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.Ek
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moreover if
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.Pf \*(Ba Fa n
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\-
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.Sm off
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.Fa x No / Fa y No \*(Ba
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.Sm on
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=
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1/2
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then
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.Fa n
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is even.
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Consequently the remainder is computed exactly and
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.Sm off
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.Pf \*(Ba Fa r No \*(Ba
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.Sm on
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\*(Le
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.Sm off
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.Pf \*(Ba Fa y No \*(Ba/2 .
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.Sm on
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But
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.Fn remainder x 0
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and
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.Fn remainder \*(If 0
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are invalid operations that produce a \*(Na.
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.Pp
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.Fn scalbn
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returns
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.Fa x Ns \(**(2** Ns Fa n )
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computed by exponent manipulation.
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.Sh SEE ALSO
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.Xr math 3
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.Sh STANDARDS
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.St -ieee754
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.Sh HISTORY
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The
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.Nm ieee
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functions appeared in
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.Bx 4.3 .
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