88 lines
2.8 KiB
C++
88 lines
2.8 KiB
C++
// -*- mode: c++; c-indent-level: 4; c++-member-init-indent: 8; comment-column: 35; -*-
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//-----------------------------------------------------------------------------
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// eoNormal.h
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// (c) GeNeura Team, 1998
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/*
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2 of the License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with this library; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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Contact: todos@geneura.ugr.es, http://geneura.ugr.es
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*/
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//-----------------------------------------------------------------------------
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#ifndef _EONORMAL_H
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#define _EONORMAL_H
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//-----------------------------------------------------------------------------
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#include <math.h>
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#include <eoRnd.h> // for base class
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#include <eoRNG.h> // for random number generator
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//-----------------------------------------------------------------------------
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// Class eoNormal
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//-----------------------------------------------------------------------------
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/// Generates random number using a normal distribution
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template<class T>
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class eoNormal: public eoRnd<T>
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{
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public:
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/**
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* Default constructor.
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* @param _mean Dsitribution mean
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* @param _sd Standard Deviation
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*/
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eoNormal(T _mean, T _sd)
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: eoRnd<T>(), mean(_mean), sd(_sd), phase(false) {}
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/**
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* Copy constructor.
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* @param _rnd the other one
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*/
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eoNormal( const eoNormal& _rnd )
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: eoRnd<T>( _rnd), mean(_rnd.mean), sd(_rnd.sd), phase(false) {}
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/** Returns an uniform random number over the interval [min, max).
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@return an uniform random number over the interval [min, max).
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*/
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virtual T operator()() {
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if (phase) { // Already have one stored up.
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phase = false;
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return T ( (sqRatio * q * sd) + mean );
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}
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double p, v;
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do {
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p = ((double)rng.rand() / rng.rand_max())*2-1;
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q = ((double)rng.rand() / rng.rand_max())*2-1;
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v = p*p + q*q;
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} while(v > 1.0 || v <0.25);
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sqRatio = sqrt(-2*log((double)rand() / rng.rand_max()) / v);
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phase = true;
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return T( (sqRatio * p * sd) + mean );
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};
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private:
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T mean;
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T sd;
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bool phase;
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double sqRatio, q;
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};
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//-----------------------------------------------------------------------------
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#endif
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