2f90a15e14
These routines are specified in C99 for the sake of architectures where an int isn't big enough to represent the full range of floating-point exponents. However, even the 128-bit long double format has an exponent smaller than 15 bits, so for all practical purposes, scalbln() and scalblnf() are aliases for scalbn() and scalbnf(), respectively.
206 lines
4.3 KiB
Groff
206 lines
4.3 KiB
Groff
.\" 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. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. 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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.\" $FreeBSD$
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.\"
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.Dd June 20, 2004
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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 remainder ,
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.Nm remainderf ,
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.Nm scalbln ,
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.Nm scalblnf ,
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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 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 scalbln "double x" "long n"
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.Ft float
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.Fn scalblnf "float x" "long n"
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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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.Fn copysignf
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and
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.Fn copysignl
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return
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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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and
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.Fn finitef
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return 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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and
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.Fn ilogbf
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return
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.Fa x Ns 's exponent,
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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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.Fn ilogb \*(Pm\*(Na
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returns
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.Dv FP_ILOGBNAN
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and
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.Fn ilogb 0
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returns
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.Dv FP_ILOGB0 .
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.Pp
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.Fn nextafter
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and
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.Fn nextafterf
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return 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 remainder
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and
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.Fn remainderf
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return 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. Consequently
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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 scalbln ,
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.Fn scalblnf ,
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.Fn scalbn ,
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and
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.Fn scalbnf
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return
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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 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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The
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.Fn copysignl ,
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.Fn scalbln ,
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and
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.Fn scalblnf
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functions first appeared in
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.Fx 5.3 .
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.Sh STANDARDS
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.St -ieee754
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