code: //==============================================================================
  //	
  //	Copyright (c) 2002-
  //	Authors:
  //	* Vincent Nimal <vincent.nimal@comlab.ox.ac.uk> (University of Oxford)
  //	* Dave Parker <david.parker@comlab.ox.ac.uk> (University of Oxford)
  //	
  //------------------------------------------------------------------------------
  //	
  //	This file is part of PRISM.
  //	
  //	PRISM is free software; you can redistribute it and/or modify
  //	it under the terms of the GNU General Public License as published by
  //	the Free Software Foundation; either version 2 of the License, or
  //	(at your option) any later version.
  //	
  //	PRISM is distributed in the hope that it will be useful,
  //	but WITHOUT ANY WARRANTY; without even the implied warranty of
  //	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  //	GNU General Public License for more details.
  //	
  //	You should have received a copy of the GNU General Public License
  //	along with PRISM; if not, write to the Free Software Foundation,
  //	Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  //	
  //==============================================================================
  
  package simulator.method;
  
  import prism.PrismException;
  
  /**
   * SimulationMethod class for the APMC ("approximate probabilistic model checking")
   * approach of Herault/Lassaigne/Magniette/Peyronnet (VMCAI'04).
   * Case where 'iterations' (number of samples) is unknown parameter.
   */
  public class APMCiterations extends APMCMethod
  {
  	public APMCiterations(double confidence, double approximation)
  	{
  		this.confidence = confidence;
  		this.approximation = approximation;
  	}
  
  	@Override
  	public void computeMissingParameterBeforeSim() throws PrismException
  	{
  		double missing = Math.ceil(0.5 * Math.log(2.0 / confidence) / (approximation * approximation));
  		if (missing < (double) Integer.MAX_VALUE) {
  			numSamples = (int) missing;
  			missingParameterComputed = true;
  		} else {
  			throw new PrismException("Overflow in APMC method: required number of iterations is too high");
  		}
  	}
  
  	@Override
  	public Object getMissingParameter() throws PrismException
  	{
  		if (!missingParameterComputed)
  			computeMissingParameterBeforeSim();
  		return numSamples;
  	}
  	
  	@Override
  	public String getParametersString()
  	{
  		if (!missingParameterComputed)
  			return "approximation=" + approximation + ", confidence=" + confidence + ", number of samples=" + "unknown";
  		else
  			return "approximation=" + approximation + ", confidence=" + confidence + ", number of samples=" + numSamples;
  	}
  	
  	@Override
  	public SimulationMethod clone()
  	{
  		APMCiterations m = new APMCiterations(confidence, approximation);
  		m.numSamples = numSamples;
  		m.missingParameterComputed = missingParameterComputed;
  		m.prOp = prOp;
  		m.theta = theta;
  		return m;
  	}
  }
  