Continuous.java

/*
 * Class:        Continuous
 * Description:  provides the basic structures and tools for 
                 continuous-time simulation
 * Environment:  Java
 * Software:     SSJ 
 * Copyright (C) 2001  Pierre L'Ecuyer and Universite de Montreal
 * Organization: DIRO, Universite de Montreal
 * @author       
 * @since
 *
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */
package umontreal.ssj.simevents;

public abstract class Continuous {
 
   // Private variables:
 
   boolean active; // This variable is currently being integrated.
   double value; // Current value of the variable.
   Event ev; // Event to be executed after each integ. step,
 
   // String name;
   double phi;
   double pi;
   double buffer;
   double sum;
 
   private Simulator sim;

   public Continuous() {
      active = false;
      this.sim = Simulator.getDefaultSimulator();
   }

   public Continuous(Simulator sim) {
      if (sim == null)
         throw new NullPointerException();
      active = false;
      this.sim = sim;
   }

   public void init(double val) {
      value = val;
   }

   public double value() {
      return value;
   }

   public Simulator simulator() {
      return sim;
   }

   public void setSimulator(Simulator sim) {
      if (sim == null)
         throw new NullPointerException();
      this.sim = sim;
   }

   public void startInteg() {
      sim.continuousState().startInteg(this);
   }

   public void startInteg(double val) {
      init(val);
      startInteg();
   }

   public void stopInteg() {
      sim.continuousState().stopInteg(this);
   }

   public abstract double derivative(double t);

   public void afterEachStep() {
   }

   public static void selectEuler(double h) {
      Simulator.getDefaultSimulator().continuousState().selectEuler(h);
   }

   public static void selectRungeKutta4(double h) {
      Simulator.getDefaultSimulator().continuousState().selectRungeKutta4(h);
   }

   public static void selectRungeKutta2(double h) {
      Simulator.getDefaultSimulator().continuousState().selectRungeKutta2(h);
   }
 
}