permlib 0.2.9
Library for permutation computations
random_schreier_generator.h
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5// Copyright (c) 2009-2011 Thomas Rehn <thomas@carmen76.de>
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31
32
33#ifndef RANDOMSCHREIERGENERATOR_H_
34#define RANDOMSCHREIERGENERATOR_H_
35
36#include <permlib/generator/random_generator.h>
37
38namespace permlib {
39
41
45template <class PERM,class TRANS>
47public:
49
54 RandomSchreierGenerator(const BSGS<PERM,TRANS> &bsgs, unsigned int i, const TRANS &U);
55 virtual PERM next();
56private:
57 const BSGS<PERM,TRANS> &m_bsgs;
58 unsigned int m_i;
59 const TRANS &m_U;
60};
61
62//
63// ---- IMPLEMENTATION
64//
65
66template <class PERM,class TRANS>
68 : m_bsgs(bsgs), m_i(i), m_U(U)
69{ }
70
71template <class PERM,class TRANS>
73 PERM g = m_bsgs.random(m_i);
74 boost::scoped_ptr<PERM> u_g(m_U.at(g / m_bsgs.B[m_i]));
75 u_g->invertInplace();
76 g *= *u_g;
77 return g;
78}
79
80}
81
82#endif // -- RANDOMSCHREIERGENERATOR_H_
abstract base class for random group element generators
Definition: random_generator.h:42
generates a uniformly distributed random element of
Definition: random_schreier_generator.h:46
RandomSchreierGenerator(const BSGS< PERM, TRANS > &bsgs, unsigned int i, const TRANS &U)
constructor
Definition: random_schreier_generator.h:67
virtual PERM next()
generates an element
Definition: random_schreier_generator.h:72
Represents a base and strong generating set (BSGS)
Definition: bsgs.h:89