code: //==============================================================================
  //	
  //	Copyright (c) 2013-
  //	Authors:
  //	* Dave Parker <david.parker@comlab.ox.ac.uk> (University of Oxford)
  //	* Ernst Moritz Hahn <emhahn@cs.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 param;
  
  import java.util.ArrayList;
  
  /**
   * Searches for bounds of minimal/maximal values.
   * 
   * @author Ernst Moritz Hahn <emhahn@cs.ox.ac.uk> (University of Oxford)
   */
  final class Optimiser {
  	RegionValues values;
  	RegionValues filter;
  	boolean min;
  
  	public Optimiser(RegionValues values, RegionValues filter, boolean min) {
  		this.values = values;
  		this.filter = filter;
  		this.min = min;
  	}
  
  	public String optimise() {
  		int numStates = values.getResult(0).getNumStates();
  		BigRational[] bounds = new BigRational[numStates];
  		for (int state = 0; state < numStates; state++) {
  			bounds[state] = min ? BigRational.INF : BigRational.MINF;
  		}
  		Point[] optPoints = new Point[numStates];
  		
  		RegionValuesIntersections co = new RegionValuesIntersections(values, filter);
  		for (RegionIntersection inter : co) {
  			Region region = inter.getRegion();
  			StateValues value1 = inter.getStateValues1();
  			StateValues value2 = inter.getStateValues2();
  			for (int state = 0; state < value1.getNumStates(); state++) {
  				ArrayList<Point> edges = region.specialPoints();
  				for (Point edge : edges) {
  					BigRational currentValue = value1.getStateValueAsFunction(state).evaluate(edge);
  					if (value2.getStateValueAsBoolean(state)) {
  						if (currentValue.compareTo(bounds[state]) == (min ? -1 : 1)) {
  							bounds[state] = currentValue;
  							optPoints[state] = edge;
  						}
  					}
  				}
  			}
  		}
  		
  		BigRational initBound = bounds[values.getInitState()];
  		
  		return (min ? "at most " : "at least ") + initBound.doubleValue() + " at " + optPoints[values.getInitState()];
  	}
  
  }
  