0dc9e0996a
As the current libc includes a libm implementation, with the new libc this is needed. Unneeded (for the moment) archs have been removed.
124 lines
3.4 KiB
Groff
124 lines
3.4 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. 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: @(#)lgamma.3 6.6 (Berkeley) 12/3/92
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.\" $NetBSD: lgamma.3,v 1.21 2003/08/07 16:44:48 agc Exp $
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.\"
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.Dd December 3, 1992
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.Dt LGAMMA 3
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.Os
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.Sh NAME
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.Nm lgamma ,
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.Nm lgammaf ,
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.Nm lgamma_r ,
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.Nm lgammaf_r ,
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.Nm gamma ,
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.Nm gammaf ,
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.Nm gamma_r ,
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.Nm gammaf_r
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.Nd log gamma function
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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 extern int
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.Fa signgam ;
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.sp
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.Ft double
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.Fn lgamma "double x"
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.Ft float
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.Fn lgammaf "float x"
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.Ft double
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.Fn lgamma_r "double x" "int *sign"
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.Ft float
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.Fn lgammaf_r "float x" "int *sign"
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.Ft double
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.Fn gamma "double x"
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.Ft float
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.Fn gammaf "float x"
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.Ft double
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.Fn gamma_r "double x" "int *sign"
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.Ft float
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.Fn gammaf_r "float x" "int *sign"
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.Sh DESCRIPTION
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.Fn lgamma x
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.if t \{\
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returns ln\||\(*G(x)| where
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.Bd -unfilled -offset indent
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\(*G(x) = \(is\d\s8\z0\s10\u\u\s8\(if\s10\d t\u\s8x\-1\s10\d e\u\s8\-t\s10\d dt for x \*[Gt] 0 and
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.br
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\(*G(x) = \(*p/(\(*G(1\-x)\|sin(\(*px)) for x \*[Lt] 1.
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.Ed
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.\}
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.if n \
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returns ln\||\(*G(x)|.
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.Pp
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The external integer
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.Fa signgam
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returns the sign of \(*G(x).
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.Pp
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.Fn lgamma_r
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is a reentrant interface that performs identically to
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.Fn lgamma ,
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differing in that the sign of \(*G(x) is stored in the location
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pointed to by the
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.Fa sign
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argument and
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.Fa signgam
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is not modified.
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.Sh IDIOSYNCRASIES
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Do not use the expression
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.Dq Li signgam\(**exp(lgamma(x))
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to compute g := \(*G(x).
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Instead use a program like this (in C):
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.Bd -literal -offset indent
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lg = lgamma(x); g = signgam\(**exp(lg);
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.Ed
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.Pp
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Only after
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.Fn lgamma
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has returned can signgam be correct.
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.Sh RETURN VALUES
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.Fn lgamma
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returns appropriate values unless an argument is out of range.
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Overflow will occur for sufficiently large positive values, and
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non-positive integers.
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On the
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.Tn VAX ,
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the reserved operator is returned,
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and
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.Va errno
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is set to
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.Er ERANGE .
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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 lgamma
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function appeared in
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.Bx 4.3 .
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