org.apache.commons.math3.ode

Class ContinuousOutputFieldModel<T extends RealFieldElement<T>>

java.lang.Object

org.apache.commons.math3.ode.ContinuousOutputFieldModel<T>

Type Parameters:

T - the type of the field elements

All Implemented Interfaces:

FieldStepHandler<T>

public class ContinuousOutputFieldModel<T extends RealFieldElement<T>>
extends java.lang.Object
implements FieldStepHandler<T>

This class stores all information provided by an ODE integrator during the integration process and build a continuous model of the solution from this.

This class act as a step handler from the integrator point of view. It is called iteratively during the integration process and stores a copy of all steps information in a sorted collection for later use. Once the integration process is over, the user can use the getInterpolatedState method to retrieve this information at any time. It is important to wait for the integration to be over before attempting to call getInterpolatedState(RealFieldElement) because some internal variables are set only once the last step has been handled.

This is useful for example if the main loop of the user application should remain independent from the integration process or if one needs to mimic the behaviour of an analytical model despite a numerical model is used (i.e. one needs the ability to get the model value at any time or to navigate through the data).

If problem modeling is done with several separate integration phases for contiguous intervals, the same ContinuousOutputModel can be used as step handler for all integration phases as long as they are performed in order and in the same direction. As an example, one can extrapolate the trajectory of a satellite with one model (i.e. one set of differential equations) up to the beginning of a maneuver, use another more complex model including thrusters modeling and accurate attitude control during the maneuver, and revert to the first model after the end of the maneuver. If the same continuous output model handles the steps of all integration phases, the user do not need to bother when the maneuver begins or ends, he has all the data available in a transparent manner.

One should be aware that the amount of data stored in a ContinuousOutputFieldModel instance can be important if the state vector is large, if the integration interval is long or if the steps are small (which can result from small tolerance settings in adaptive step size integrators).

Since:

3.6

See Also:

FieldStepHandler, FieldStepInterpolator

Field Summary

Fields

Modifier and Type	Field and Description
private T	finalTime Final integration time.
private boolean	forward Integration direction indicator.
private int	index Current interpolator index.
private T	initialTime Initial integration time.
private java.util.List<FieldStepInterpolator<T>>	steps Steps table.

Constructor Summary

Constructors

Constructor and Description
ContinuousOutputFieldModel() Simple constructor.

Method Summary

Methods

Modifier and Type	Method and Description
void	append(ContinuousOutputFieldModel<T> model) Append another model at the end of the instance.
private void	checkDimensionsEquality(int d1, int d2) Check dimensions equality.
T	getFinalTime() Get the final integration time.
T	getInitialTime() Get the initial integration time.
FieldODEStateAndDerivative<T>	getInterpolatedState(T time) Get the state at interpolated time.
void	handleStep(FieldStepInterpolator<T> interpolator, boolean isLast) Handle the last accepted step.
void	init(FieldODEStateAndDerivative<T> initialState, T t) Initialize step handler at the start of an ODE integration.
private int	locatePoint(T time, FieldStepInterpolator<T> interval) Compare a step interval and a double.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

initialTime

private T extends RealFieldElement<T> initialTime

Initial integration time.

finalTime

private T extends RealFieldElement<T> finalTime

Final integration time.

forward

private boolean forward

Integration direction indicator.

index

private int index

Current interpolator index.

steps

private java.util.List<FieldStepInterpolator<T extends RealFieldElement<T>>> steps

Steps table.

Constructor Detail

ContinuousOutputFieldModel

public ContinuousOutputFieldModel()

Simple constructor. Build an empty continuous output model.

Method Detail

append

public void append(ContinuousOutputFieldModel<T> model)
            throws MathIllegalArgumentException,
                   MaxCountExceededException

Append another model at the end of the instance.

Parameters:

model - model to add at the end of the instance

Throws:

MathIllegalArgumentException - if the model to append is not compatible with the instance (dimension of the state vector, propagation direction, hole between the dates)

DimensionMismatchException - if the dimensions of the states or the number of secondary states do not match

MaxCountExceededException - if the number of functions evaluations is exceeded during step finalization

checkDimensionsEquality

private void checkDimensionsEquality(int d1,
                           int d2)
                              throws DimensionMismatchException

Check dimensions equality.

Parameters:

d1 - first dimension

d2 - second dimansion

Throws:

DimensionMismatchException - if dimensions do not match

init

public void init(FieldODEStateAndDerivative<T> initialState,
        T t)

Initialize step handler at the start of an ODE integration.

This method is called once at the start of the integration. It may be used by the step handler to initialize some internal data if needed.

Specified by:

init in interface FieldStepHandler<T extends RealFieldElement<T>>

Parameters:

initialState - initial time, state vector and derivative

t - target time for the integration

handleStep

public void handleStep(FieldStepInterpolator<T> interpolator,
              boolean isLast)
                throws MaxCountExceededException

Handle the last accepted step. A copy of the information provided by the last step is stored in the instance for later use.

Specified by:

handleStep in interface FieldStepHandler<T extends RealFieldElement<T>>

Parameters:

interpolator - interpolator for the last accepted step.

isLast - true if the step is the last one

Throws:

MaxCountExceededException - if the number of functions evaluations is exceeded during step finalization

getInitialTime

public T getInitialTime()

Get the initial integration time.

Returns:

initial integration time

getFinalTime

public T getFinalTime()

Get the final integration time.

Returns:

final integration time

getInterpolatedState

public FieldODEStateAndDerivative<T> getInterpolatedState(T time)

Get the state at interpolated time.

Parameters:

time - time of the interpolated point

Returns:

state at interpolated time

locatePoint

private int locatePoint(T time,
              FieldStepInterpolator<T> interval)

Compare a step interval and a double.

Parameters:

time - point to locate

interval - step interval

Returns:

-1 if the double is before the interval, 0 if it is in the interval, and +1 if it is after the interval, according to the interval direction