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 * The ASF licenses this file to You under the Apache License, Version 2.0
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 *      http://www.apache.org/licenses/LICENSE-2.0
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package org.apache.commons.math3.ode;

import java.util.Collection;

import org.apache.commons.math3.analysis.solvers.UnivariateSolver;
import org.apache.commons.math3.ode.events.EventHandler;
import org.apache.commons.math3.ode.sampling.StepHandler;

This interface defines the common parts shared by integrators
for first and second order differential equations.
See Also:
FirstOrderIntegrator
SecondOrderIntegrator
Since:
2.0/**
 * This interface defines the common parts shared by integrators
 * for first and second order differential equations.
 * @see FirstOrderIntegrator
 * @see SecondOrderIntegrator
 * @since 2.0
 */
public interface ODEIntegrator  {

    
Get the name of the method.
Returns:
name of the method/** Get the name of the method.
     * @return name of the method
     */
    String getName();

    
Add a step handler to this integrator.
The handler will be called by the integrator for each accepted
step.
Params:
handler – handler for the accepted steps
See Also:
getStepHandlers()
clearStepHandlers()
Since:
2.0/** Add a step handler to this integrator.
     * <p>The handler will be called by the integrator for each accepted
     * step.</p>
     * @param handler handler for the accepted steps
     * @see #getStepHandlers()
     * @see #clearStepHandlers()
     * @since 2.0
     */
    void addStepHandler(StepHandler handler);

    
Get all the step handlers that have been added to the integrator.
See Also:
addStepHandler(StepHandler)
clearStepHandlers()
Returns:
an unmodifiable collection of the added events handlers
Since:
2.0/** Get all the step handlers that have been added to the integrator.
     * @return an unmodifiable collection of the added events handlers
     * @see #addStepHandler(StepHandler)
     * @see #clearStepHandlers()
     * @since 2.0
     */
    Collection<StepHandler> getStepHandlers();

    
Remove all the step handlers that have been added to the integrator.
See Also:
addStepHandler(StepHandler)
getStepHandlers()
Since:
2.0/** Remove all the step handlers that have been added to the integrator.
     * @see #addStepHandler(StepHandler)
     * @see #getStepHandlers()
     * @since 2.0
     */
    void clearStepHandlers();

    
Add an event handler to the integrator. Uses a default UnivariateSolver with an absolute accuracy equal to the given convergence threshold, as root-finding algorithm to detect the state events. 
Params:
handler – event handler
maxCheckInterval – maximal time interval between switching
function checks (this interval prevents missing sign changes in
case the integration steps becomes very large)
convergence – convergence threshold in the event time search
maxIterationCount – upper limit of the iteration count in
the event time search
See Also:
getEventHandlers()
clearEventHandlers()/** Add an event handler to the integrator.
     * Uses a default {@link UnivariateSolver}
     * with an absolute accuracy equal to the given convergence threshold,
     * as root-finding algorithm to detect the state events.
     * @param handler event handler
     * @param maxCheckInterval maximal time interval between switching
     * function checks (this interval prevents missing sign changes in
     * case the integration steps becomes very large)
     * @param convergence convergence threshold in the event time search
     * @param maxIterationCount upper limit of the iteration count in
     * the event time search
     * @see #getEventHandlers()
     * @see #clearEventHandlers()
     */
    void addEventHandler(EventHandler handler, double maxCheckInterval,
                         double convergence, int maxIterationCount);

    
Add an event handler to the integrator.
Params:
handler – event handler
maxCheckInterval – maximal time interval between switching
function checks (this interval prevents missing sign changes in
case the integration steps becomes very large)
convergence – convergence threshold in the event time search
maxIterationCount – upper limit of the iteration count in
the event time search
solver – The root-finding algorithm to use to detect the state
events.
See Also:
getEventHandlers()
clearEventHandlers()/** Add an event handler to the integrator.
     * @param handler event handler
     * @param maxCheckInterval maximal time interval between switching
     * function checks (this interval prevents missing sign changes in
     * case the integration steps becomes very large)
     * @param convergence convergence threshold in the event time search
     * @param maxIterationCount upper limit of the iteration count in
     * the event time search
     * @param solver The root-finding algorithm to use to detect the state
     * events.
     * @see #getEventHandlers()
     * @see #clearEventHandlers()
     */
    void addEventHandler(EventHandler handler, double maxCheckInterval,
                         double convergence, int maxIterationCount,
                         UnivariateSolver solver);

    
Get all the event handlers that have been added to the integrator.
See Also:
addEventHandler(EventHandler, double, double, int)
clearEventHandlers()
Returns:
an unmodifiable collection of the added events handlers/** Get all the event handlers that have been added to the integrator.
     * @return an unmodifiable collection of the added events handlers
     * @see #addEventHandler(EventHandler, double, double, int)
     * @see #clearEventHandlers()
     */
    Collection<EventHandler> getEventHandlers();

    
Remove all the event handlers that have been added to the integrator.
See Also:
addEventHandler(EventHandler, double, double, int)
getEventHandlers()/** Remove all the event handlers that have been added to the integrator.
     * @see #addEventHandler(EventHandler, double, double, int)
     * @see #getEventHandlers()
     */
    void clearEventHandlers();

    
Get the current value of the step start time ti.
This method can be called during integration (typically by the object implementing the 
differential equations problem) if the value of the current step that is attempted is needed.
The result is undefined if the method is called outside of
calls to integrate.
Returns:
current value of the step start time ti/** Get the current value of the step start time t<sub>i</sub>.
     * <p>This method can be called during integration (typically by
     * the object implementing the {@link FirstOrderDifferentialEquations
     * differential equations} problem) if the value of the current step that
     * is attempted is needed.</p>
     * <p>The result is undefined if the method is called outside of
     * calls to <code>integrate</code>.</p>
     * @return current value of the step start time t<sub>i</sub>
     */
    double getCurrentStepStart();

    
Get the current signed value of the integration stepsize.
This method can be called during integration (typically by the object implementing the 
differential equations problem) if the signed value of the current stepsize that is tried is needed.
The result is undefined if the method is called outside of
calls to integrate.
Returns:
current signed value of the stepsize/** Get the current signed value of the integration stepsize.
     * <p>This method can be called during integration (typically by
     * the object implementing the {@link FirstOrderDifferentialEquations
     * differential equations} problem) if the signed value of the current stepsize
     * that is tried is needed.</p>
     * <p>The result is undefined if the method is called outside of
     * calls to <code>integrate</code>.</p>
     * @return current signed value of the stepsize
     */
    double getCurrentSignedStepsize();

    
Set the maximal number of differential equations function evaluations.
The purpose of this method is to avoid infinite loops which can occur
for example when stringent error constraints are set or when lots of
discrete events are triggered, thus leading to many rejected steps.
Params:
maxEvaluations – maximal number of function evaluations (negative
values are silently converted to maximal integer value, thus representing
almost unlimited evaluations)/** Set the maximal number of differential equations function evaluations.
     * <p>The purpose of this method is to avoid infinite loops which can occur
     * for example when stringent error constraints are set or when lots of
     * discrete events are triggered, thus leading to many rejected steps.</p>
     * @param maxEvaluations maximal number of function evaluations (negative
     * values are silently converted to maximal integer value, thus representing
     * almost unlimited evaluations)
     */
    void setMaxEvaluations(int maxEvaluations);

    
Get the maximal number of functions evaluations.
Returns:
maximal number of functions evaluations/** Get the maximal number of functions evaluations.
     * @return maximal number of functions evaluations
     */
    int getMaxEvaluations();

    
Get the number of evaluations of the differential equations function.

The number of evaluations corresponds to the last call to the
integrate method. It is 0 if the method has not been called yet.

Returns:
number of evaluations of the differential equations function/** Get the number of evaluations of the differential equations function.
     * <p>
     * The number of evaluations corresponds to the last call to the
     * <code>integrate</code> method. It is 0 if the method has not been called yet.
     * </p>
     * @return number of evaluations of the differential equations function
     */
    int getEvaluations();

}