code: //==============================================================================
  //	
  //	Copyright (c) 2002-
  //	Authors:
  //	* 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 explicit;
  
  import java.util.Map;
  
  import prism.ModelType;
  import prism.PrismUtils;
  
  /**
   * Simple explicit-state representation of a CTMDP.
   */
  public class CTMDPSimple extends MDPSimple implements CTMDP
  {
  	// Constructors
  
  	/**
  	 * Constructor: empty CTMDP.
  	 */
  	public CTMDPSimple()
  	{
  		initialise(0);
  	}
  
  	/**
  	 * Constructor: new CTMDP with fixed number of states.
  	 */
  	public CTMDPSimple(int numStates)
  	{
  		initialise(numStates);
  	}
  
  	/**
  	 * Copy constructor.
  	 */
  	public CTMDPSimple(CTMDPSimple ctmdp)
  	{
  		super(ctmdp);
  	}
  
  	/**
  	 * Construct a CTMDP from an existing one and a state index permutation,
  	 * i.e. in which state index i becomes index permut[i].
  	 * Note: have to build new Distributions from scratch anyway to do this,
  	 * so may as well provide this functionality as a constructor.
  	 */
  	public CTMDPSimple(CTMDPSimple ctmdp, int permut[])
  	{
  		super(ctmdp, permut);
  	}
  
  	// Accessors (for ModelSimple)
  
  	@Override
  	public ModelType getModelType()
  	{
  		return ModelType.CTMDP;
  	}
  
  	// Accessors (for CTMDP)
  
  	@Override
  	public double getMaxExitRate()
  	{
  		int i;
  		double d, max = Double.NEGATIVE_INFINITY;
  		for (i = 0; i < numStates; i++) {
  			for (Distribution distr : trans.get(i)) {
  				d = distr.sum();
  				if (d > max)
  					max = d;
  			}
  		}
  		return max;
  	}
  
  	@Override
  	public boolean isLocallyUniform()
  	{
  		int i, j, n;
  		double d;
  		for (i = 0; i < numStates; i++) {
  			n = trans.get(i).size();
  			if (n < 2)
  				continue;
  			d = trans.get(i).get(0).sum();
  			for (j = 1; j < n; j++) {
  				if (!PrismUtils.doublesAreCloseAbs(trans.get(i).get(j).sum(), d, 1e-12))
  					return false;
  			}
  		}
  		return true;
  	}
  
  	@Override
  	public MDP buildImplicitDiscretisedMDP(double tau)
  	{
  		// TODO
  		return null;
  	}
  
  	@Override
  	public MDPSimple buildDiscretisedMDP(double tau)
  	{
  		MDPSimple mdp;
  		Distribution distrNew;
  		int i;
  		double sum, d;
  		mdp = new MDPSimple(numStates);
  		for (int in : getInitialStates()) {
  			mdp.addInitialState(in);
  		}
  		for (i = 0; i < numStates; i++) {
  			for (Distribution distr : trans.get(i)) {
  				distrNew = new Distribution();
  				sum = distr.sum();
  				d = Math.exp(-sum * tau);
  				for (Map.Entry<Integer, Double> e : distr) {
  					distrNew.add(e.getKey(), (1 - d) * (e.getValue() / sum));
  				}
  				distrNew.add(i, d);
  				mdp.addChoice(i, distrNew);
  			}
  		}
  		return mdp;
  	}
  }
  