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include
permlib
generator
random_schreier_generator.h
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// ---------------------------------------------------------------------------
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//
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// This file is part of PermLib.
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//
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// Copyright (c) 2009-2011 Thomas Rehn <thomas@carmen76.de>
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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. The name of the author may not be used to endorse or promote products
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// derived from this software without specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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// IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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// OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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// IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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// NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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// THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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//
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// ---------------------------------------------------------------------------
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#ifndef RANDOMSCHREIERGENERATOR_H_
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#define RANDOMSCHREIERGENERATOR_H_
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#include <permlib/generator/random_generator.h>
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namespace
permlib {
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template
<
class
PERM,
class
TRANS>
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class
RandomSchreierGenerator
:
public
RandomGenerator
<PERM> {
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public
:
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RandomSchreierGenerator
(
const
BSGS<PERM,TRANS>
&bsgs,
unsigned
int
i,
const
TRANS &U);
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virtual
PERM
next
();
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private
:
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const
BSGS<PERM,TRANS>
&m_bsgs;
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unsigned
int
m_i;
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const
TRANS &m_U;
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};
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//
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// ---- IMPLEMENTATION
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//
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template
<
class
PERM,
class
TRANS>
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RandomSchreierGenerator<PERM,TRANS>::RandomSchreierGenerator
(
const
BSGS<PERM,TRANS>
&bsgs,
unsigned
int
i,
const
TRANS &U)
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: m_bsgs(bsgs), m_i(i), m_U(U)
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{ }
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template
<
class
PERM,
class
TRANS>
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PERM
RandomSchreierGenerator<PERM,TRANS>::next
() {
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PERM g = m_bsgs.random(m_i);
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boost::scoped_ptr<PERM> u_g(m_U.at(g / m_bsgs.B[m_i]));
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u_g->invertInplace();
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g *= *u_g;
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return
g;
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}
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}
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#endif // -- RANDOMSCHREIERGENERATOR_H_
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