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This work is based in part on code from NetBSD libm, libc and kernel. The library is partly public domain and partly BSD-style licensed.
108 lines
3 KiB
Groff
108 lines
3 KiB
Groff
.\" $NetBSD: scalbn.3,v 1.2 2011/09/18 05:33:14 jruoho Exp $
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.\"
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.\" Copyright (c) 2011 Jukka Ruohonen <jruohonen@iki.fi>
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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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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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.Dd September 18, 2011
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.Dt SCALBN 3
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.Os
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.Sh NAME
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.Nm scalbn ,
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.Nm scalbnf ,
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.Nm scalbnl
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.Nd exponent using FLT_RADIX
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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 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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.Ft long double
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.Fn scalbnl "long double x" "int n"
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.Sh DESCRIPTION
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The
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.Fn scalbn ,
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.Fn scalbnf ,
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and
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.Fn scalbnl
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functions compute
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.Fa x
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*
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.Fa r^n ,
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where
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.Fa r
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is the radix of the machine's floating point arithmetic, defined by the
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.Dv FLT_RADIX
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constant in
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.In float.h .
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The rationale is efficiency;
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.Fa r^n
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is not computed explicitly.
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.Sh RETURN VALUES
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As described above, upon successful completion, the described functions return
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the exponent computed using
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.Dv FLT_RADIX .
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Otherwise the following may occur:
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.Pp
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.Bl -enum -offset indent
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.It
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When the result would cause an overflow, a range error occurs and
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.Dv \*(Pm\*HHUGE_VAL ,
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.Dv \*(Pm\*HHUGE_VALF ,
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or
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.Dv \*(Pm\*HHUGE_VALL
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is returned according to the sign of
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.Fa x
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and the return type of the corresponding function.
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.It
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When the correct value would cause an underflow
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and it is not representable, a range error occurs and
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either 0.0 or an implementation-defined value is returned.
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When an underflow occurs but the correct value is representable,
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a range error occurs but the correct value is returned.
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.It
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If
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.Fa x
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is \*(Pm0 or \*(Pm\Inf,
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.Fa x
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is returned.
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Likewise, if
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.Fa n
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is zero,
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.Fa x
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is returned.
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If
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.Fa x
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is \*(Na, \*(Na is returned.
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.El
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.Sh SEE ALSO
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.Xr exp 3 ,
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.Xr frexp 3 ,
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.Xr ldexp 3 ,
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.Xr math 3
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.Sh STANDARDS
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The described functions conform to
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.St -isoC-99 .
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