org.apache.commons.math.ode
Class AbstractIntegrator.EndTimeChecker

java.lang.Object
  extended by org.apache.commons.math.ode.AbstractIntegrator.EndTimeChecker
All Implemented Interfaces:
EventHandler
Enclosing class:
AbstractIntegrator

private static class AbstractIntegrator.EndTimeChecker
extends Object
implements EventHandler

Specialized event handler to stop integration.


Field Summary
private  double endTime
          Desired end time.
 
Fields inherited from interface org.apache.commons.math.ode.events.EventHandler
CONTINUE, RESET_DERIVATIVES, RESET_STATE, STOP
 
Constructor Summary
AbstractIntegrator.EndTimeChecker(double endTime)
          Build an instance.
 
Method Summary
 int eventOccurred(double t, double[] y, boolean increasing)
          Handle an event and choose what to do next.
 double g(double t, double[] y)
          Compute the value of the switching function.
 void resetState(double t, double[] y)
          Reset the state prior to continue the integration.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

endTime

private final double endTime
Desired end time.

Constructor Detail

AbstractIntegrator.EndTimeChecker

public AbstractIntegrator.EndTimeChecker(double endTime)
Build an instance.

Parameters:
endTime - desired time
Method Detail

eventOccurred

public int eventOccurred(double t,
                         double[] y,
                         boolean increasing)
Handle an event and choose what to do next.

This method is called when the integrator has accepted a step ending exactly on a sign change of the function, just before the step handler itself is called. It allows the user to update his internal data to acknowledge the fact the event has been handled (for example setting a flag in the differential equations to switch the derivatives computation in case of discontinuity), or to direct the integrator to either stop or continue integration, possibly with a reset state or derivatives.

Specified by:
eventOccurred in interface EventHandler
Parameters:
t - current value of the independent time variable
y - array containing the current value of the state vector
increasing - if true, the value of the switching function increases when times increases around event (note that increase is measured with respect to physical time, not with respect to integration which may go backward in time)
Returns:
indication of what the integrator should do next, this value must be one of EventHandler.STOP, EventHandler.RESET_STATE, EventHandler.RESET_DERIVATIVES or EventHandler.CONTINUE

g

public double g(double t,
                double[] y)
Compute the value of the switching function.

The discrete events are generated when the sign of this switching function changes. The integrator will take care to change the stepsize in such a way these events occur exactly at step boundaries. The switching function must be continuous in its roots neighborhood (but not necessarily smooth), as the integrator will need to find its roots to locate precisely the events.

Specified by:
g in interface EventHandler
Parameters:
t - current value of the independent time variable
y - array containing the current value of the state vector
Returns:
value of the g switching function

resetState

public void resetState(double t,
                       double[] y)
Reset the state prior to continue the integration.

This method is called after the step handler has returned and before the next step is started, but only when EventHandler.eventOccurred(double, double[], boolean) has itself returned the EventHandler.RESET_STATE indicator. It allows the user to reset the state vector for the next step, without perturbing the step handler of the finishing step. If the EventHandler.eventOccurred(double, double[], boolean) never returns the EventHandler.RESET_STATE indicator, this function will never be called, and it is safe to leave its body empty.

Specified by:
resetState in interface EventHandler
Parameters:
t - current value of the independent time variable
y - array containing the current value of the state vector the new state should be put in the same array


Copyright (c) 2003-2010 Apache Software Foundation