org.apache.commons.math4.ode

## Class AbstractFieldIntegrator<T extends RealFieldElement<T>>

• Type Parameters:
T - the type of the field elements
All Implemented Interfaces:
FirstOrderFieldIntegrator<T>
Direct Known Subclasses:

public abstract class AbstractFieldIntegrator<T extends RealFieldElement<T>>
extends Object
implements FirstOrderFieldIntegrator<T>
Base class managing common boilerplate for all integrators.
Since:
3.6
• ### Constructor Summary

Constructors
Modifier Constructor and Description
protected  AbstractFieldIntegrator(Field<T> field, String name)
Build an instance.
• ### Method Summary

All Methods
Modifier and Type Method and Description
protected FieldODEStateAndDerivative<T> acceptStep(AbstractFieldStepInterpolator<T> interpolator, T tEnd)
Accept a step, triggering events and step handlers.
void addEventHandler(FieldEventHandler<T> handler, double maxCheckInterval, double convergence, int maxIterationCount)
Add an event handler to the integrator.
void addEventHandler(FieldEventHandler<T> handler, double maxCheckInterval, double convergence, int maxIterationCount, BracketedRealFieldUnivariateSolver<T> solver)
Add an event handler to the integrator.
void addStepHandler(FieldStepHandler<T> handler)
Add a step handler to this integrator.
void clearEventHandlers()
Remove all the event handlers that have been added to the integrator.
void clearStepHandlers()
Remove all the step handlers that have been added to the integrator.
T[] computeDerivatives(T t, T[] y)
Compute the derivatives and check the number of evaluations.
T getCurrentSignedStepsize()
Get the current signed value of the integration stepsize.
FieldODEStateAndDerivative<T> getCurrentStepStart()
Get the current value of the step start time ti.
protected FieldExpandableODE<T> getEquations()
Get the differential equations to integrate.
int getEvaluations()
Get the number of evaluations of the differential equations function.
protected IntegerSequence.Incrementor getEvaluationsCounter()
Get the evaluations counter.
Collection<FieldEventHandler<T>> getEventHandlers()
Get all the event handlers that have been added to the integrator.
Field<T> getField()
Get the field to which state vector elements belong.
int getMaxEvaluations()
Get the maximal number of functions evaluations.
String getName()
Get the name of the method.
Collection<FieldStepHandler<T>> getStepHandlers()
Get all the step handlers that have been added to the integrator.
protected T getStepSize()
Get the current step size.
protected FieldODEStateAndDerivative<T> getStepStart()
Getcurrent step start.
protected FieldODEStateAndDerivative<T> initIntegration(FieldExpandableODE<T> eqn, T t0, T[] y0, T t)
Prepare the start of an integration.
protected boolean isLastStep()
Check if this step is the last one.
protected boolean resetOccurred()
Check if a reset occurred while last step was accepted.
protected void sanityChecks(FieldODEState<T> eqn, T t)
Check the integration span.
protected void setIsLastStep(boolean isLastStep)
Set the last state flag.
void setMaxEvaluations(int maxEvaluations)
Set the maximal number of differential equations function evaluations.
protected void setStateInitialized(boolean stateInitialized)
Set the stateInitialized flag.
protected void setStepSize(T stepSize)
Set the current step size.
protected void setStepStart(FieldODEStateAndDerivative<T> stepStart)
Set current step start.
• ### Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
• ### Methods inherited from interface org.apache.commons.math4.ode.FirstOrderFieldIntegrator

integrate
• ### Constructor Detail

• #### AbstractFieldIntegrator

protected AbstractFieldIntegrator(Field<T> field,
String name)
Build an instance.
Parameters:
field - field to which the time and state vector elements belong
name - name of the method
• ### Method Detail

• #### getField

public Field<T> getField()
Get the field to which state vector elements belong.
Returns:
field to which state vector elements belong
• #### getName

public String getName()
Get the name of the method.
Specified by:
getName in interface FirstOrderFieldIntegrator<T extends RealFieldElement<T>>
Returns:
name of the method

public void addEventHandler(FieldEventHandler<T> handler,
double maxCheckInterval,
double convergence,
int maxIterationCount,
BracketedRealFieldUnivariateSolver<T> solver)
Add an event handler to the integrator.
Specified by:
addEventHandler in interface FirstOrderFieldIntegrator<T extends RealFieldElement<T>>
Parameters:
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 events.
solver - solver to use to locate the event
FirstOrderFieldIntegrator.addEventHandler(FieldEventHandler, double, double, int), FirstOrderFieldIntegrator.getEventHandlers(), FirstOrderFieldIntegrator.clearEventHandlers()
• #### getCurrentStepStart

public FieldODEStateAndDerivative<T> getCurrentStepStart()
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.

Specified by:
getCurrentStepStart in interface FirstOrderFieldIntegrator<T extends RealFieldElement<T>>
Returns:
current value of the state at step start time ti
• #### getCurrentSignedStepsize

public T getCurrentSignedStepsize()
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.

Specified by:
getCurrentSignedStepsize in interface FirstOrderFieldIntegrator<T extends RealFieldElement<T>>
Returns:
current signed value of the stepsize
• #### setMaxEvaluations

public void setMaxEvaluations(int maxEvaluations)
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.

Specified by:
setMaxEvaluations in interface FirstOrderFieldIntegrator<T extends RealFieldElement<T>>
Parameters:
maxEvaluations - maximal number of function evaluations (negative values are silently converted to maximal integer value, thus representing almost unlimited evaluations)
• #### getMaxEvaluations

public int getMaxEvaluations()
Get the maximal number of functions evaluations.
Specified by:
getMaxEvaluations in interface FirstOrderFieldIntegrator<T extends RealFieldElement<T>>
Returns:
maximal number of functions evaluations
• #### getEvaluations

public int getEvaluations()
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.

Specified by:
getEvaluations in interface FirstOrderFieldIntegrator<T extends RealFieldElement<T>>
Returns:
number of evaluations of the differential equations function
• #### initIntegration

protected FieldODEStateAndDerivative<T> initIntegration(FieldExpandableODE<T> eqn,
T t0,
T[] y0,
T t)
Prepare the start of an integration.
Parameters:
eqn - equations to integrate
t0 - start value of the independent time variable
y0 - array containing the start value of the state vector
t - target time for the integration
Returns:
• #### getEquations

protected FieldExpandableODE<T> getEquations()
Get the differential equations to integrate.
Returns:
differential equations to integrate
• #### getEvaluationsCounter

protected IntegerSequence.Incrementor getEvaluationsCounter()
Get the evaluations counter.
Returns:
evaluations counter
• #### computeDerivatives

public T[] computeDerivatives(T t,
T[] y)
throws DimensionMismatchException,
MaxCountExceededException,
NullPointerException
Compute the derivatives and check the number of evaluations.
Parameters:
t - current value of the independent time variable
y - array containing the current value of the state vector
Returns:
state completed with derivatives
Throws:
DimensionMismatchException - if arrays dimensions do not match equations settings
MaxCountExceededException - if the number of functions evaluations is exceeded
NullPointerException - if the ODE equations have not been set (i.e. if this method is called outside of a call to integrate
• #### setStateInitialized

protected void setStateInitialized(boolean stateInitialized)
Set the stateInitialized flag.

This method must be called by integrators with the value false before they start integration, so a proper lazy initialization is done automatically on the first step.

Parameters:
stateInitialized - new value for the flag
• #### acceptStep

protected FieldODEStateAndDerivative<T> acceptStep(AbstractFieldStepInterpolator<T> interpolator,
T tEnd)
throws MaxCountExceededException,
DimensionMismatchException,
NoBracketingException
Accept a step, triggering events and step handlers.
Parameters:
interpolator - step interpolator
tEnd - final integration time
Returns:
state at end of step
Throws:
MaxCountExceededException - if the interpolator throws one because the number of functions evaluations is exceeded
NoBracketingException - if the location of an event cannot be bracketed
DimensionMismatchException - if arrays dimensions do not match equations settings
• #### sanityChecks

protected void sanityChecks(FieldODEState<T> eqn,
T t)
throws NumberIsTooSmallException,
DimensionMismatchException
Check the integration span.
Parameters:
eqn - set of differential equations
t - target time for the integration
Throws:
NumberIsTooSmallException - if integration span is too small
DimensionMismatchException - if adaptive step size integrators tolerance arrays dimensions are not compatible with equations settings
• #### resetOccurred

protected boolean resetOccurred()
Check if a reset occurred while last step was accepted.
Returns:
true if a reset occurred while last step was accepted
• #### setStepSize

protected void setStepSize(T stepSize)
Set the current step size.
Parameters:
stepSize - step size to set
• #### getStepSize

protected T getStepSize()
Get the current step size.
Returns:
current step size
• #### setStepStart

protected void setStepStart(FieldODEStateAndDerivative<T> stepStart)
Set current step start.
Parameters:
stepStart - step start
• #### getStepStart

protected FieldODEStateAndDerivative<T> getStepStart()
Getcurrent step start.
Returns:
current step start
• #### setIsLastStep

protected void setIsLastStep(boolean isLastStep)
Set the last state flag.
Parameters:
isLastStep - if true, this step is the last one
• #### isLastStep

protected boolean isLastStep()
Check if this step is the last one.
Returns:
true if this step is the last one