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84 lines
2.8 KiB
84 lines
2.8 KiB
//==============================================================================
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//
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// Copyright (c) 2002-
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// Authors:
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// * Vincent Nimal <vincent.nimal@comlab.ox.ac.uk> (University of Oxford)
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// * Dave Parker <david.parker@comlab.ox.ac.uk> (University of Oxford)
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//
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//------------------------------------------------------------------------------
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//
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// This file is part of PRISM.
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//
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// PRISM is free software; you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation; either version 2 of the License, or
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// (at your option) any later version.
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//
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// PRISM 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
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with PRISM; if not, write to the Free Software Foundation,
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// Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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//
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//==============================================================================
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package simulator.method;
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import prism.PrismException;
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/**
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* SimulationMethod class for the APMC ("approximate probabilistic model checking")
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* approach of Herault/Lassaigne/Magniette/Peyronnet (VMCAI'04).
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* Case where 'confidence' is unknown parameter.
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*/
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public class APMCconfidence extends APMCMethod
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{
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public APMCconfidence(double approximation, int iterations)
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{
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this.approximation = approximation;
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this.numSamples = iterations;
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}
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@Override
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public void computeMissingParameterBeforeSim() throws PrismException
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{
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if (approximation * approximation * numSamples < Math.log(2.0) / 2.0) {
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String msg = "For APMC, samples (N) and approximation (eps) must satisfy N*eps^2 >= ln(2)/2";
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msg += ". Increase samples and/or approximation";
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throw new PrismException(msg);
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}
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confidence = 2.0 / Math.exp((numSamples * approximation * approximation) * 2.0);
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missingParameterComputed = true;
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}
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@Override
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public Object getMissingParameter() throws PrismException
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{
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if (!missingParameterComputed)
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computeMissingParameterBeforeSim();
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return confidence;
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}
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@Override
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public String getParametersString()
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{
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if (!missingParameterComputed)
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return "approximation=" + approximation + ", confidence=" + "unknown" + ", number of samples=" + numSamples;
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else
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return "approximation=" + approximation + ", confidence=" + confidence + ", number of samples=" + numSamples;
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}
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@Override
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public SimulationMethod clone()
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{
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APMCconfidence m = new APMCconfidence(approximation, numSamples);
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m.confidence = confidence;
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m.missingParameterComputed = missingParameterComputed;
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m.prOp = prOp;
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m.theta = theta;
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return m;
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}
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}
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