0ec5232d0c
standard in C99 and POSIX.1-2001+. They are also not deprecated, since apart from being standard they can handle special args slightly better than the ilogb() functions. Move their documentation to ilogb.3. Try to use consistent and improved wording for both sets of functions. All of ieee854, C99 and POSIX have better wording and more details for special args. Add history for the logb() functions and ilogbl(). Fix history for ilogb().
128 lines
3.1 KiB
Groff
128 lines
3.1 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 Nov 6, 2005
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.Dt ILOGB 3
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.Os
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.Sh NAME
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.Nm ilogb ,
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.Nm ilogbf ,
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.Nm ilogbl ,
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.Nm logb ,
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.Nm logbf
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.Nd extract exponent
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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 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 int
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.Fn ilogbl "long double x"
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.Ft double
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.Fn logb "double x"
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.Ft float
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.Fn logbf "float x"
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.Sh DESCRIPTION
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.Fn ilogb ,
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.Fn ilogbf
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and
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.Fn ilogbl
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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 logb x
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and
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.Fn logbf x
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return
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.Fa x Ns 's exponent
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in floating\-point format with the same precision as
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.Fa x .
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.Fn logb \*(Pm\*(If
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returns +\*(If, and
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.Fn logb 0
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returns -\*(If with a division by zero exception.
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.Sh SEE ALSO
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.Xr frexp 3 ,
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.Xr ieee 3 ,
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.Xr math 3 ,
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.Xr scalbn 3
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.Sh STANDARDS
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The
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.Fn ilogb ,
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.Fn ilogbf ,
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.Fn ilogbl ,
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.Fn logb
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and
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.Fn logbf
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routines conform to
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.St -isoC-99 .
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.Fn logb
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and
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.Fn logbf
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implement the logb function recommended by
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.St -ieee754 .
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.Sh HISTORY
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The
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.Fn logb
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function appeared in
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.Bx 4.3 .
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The
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.Fn ilogb
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function appeared in
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.Fx 1.1.5 .
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The
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.Fn ilogbf
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and
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.Fn logbf
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functions appeared in
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.Fx 2.0 .
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The
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.Fn ilogbl
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function appeared in
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.Fx 5.4 .
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