Apache Commons Math 3.6.1 · org.apache.commons.math3.ode.ContinuousOutputModel

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 setInterpolatedTime and getInterpolatedState to retrieve this information at any time. It is important to wait for the integration to be over before attempting to call setInterpolatedTime 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.

An important feature of this class is that it implements the Serializable interface. This means that the result of an integration can be serialized and reused later (if stored into a persistent medium like a filesystem or a database) or elsewhere (if sent to another application). Only the result of the integration is stored, there is no reference to the integrated problem by itself.

One should be aware that the amount of data stored in a ContinuousOutputModel 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).

Field Summary

Modifier and Type	Field and Description
private double	finalTime Final integration time.
private boolean	forward Integration direction indicator.
private int	index Current interpolator index.
private double	initialTime Initial integration time.
private static final long	serialVersionUID Serializable version identifier
private List<StepInterpolator>	steps Steps table.

Constructor Summary

Access	Constructor and Description
public	ContinuousOutputModel() Simple constructor.

Method Summary

Modifier and Type	Method and Description
public void	append(final ContinuousOutputModel model to add at the end of the instance model) Append another model at the end of the instance.
public double	Returns: final integration time getFinalTime() Get the final integration time.
public double	Returns: initial integration time getInitialTime() Get the initial integration time.
public double[]	Returns: derivatives of the state vector at time `getInterpolatedTime` getInterpolatedDerivatives() Get the derivatives of the state vector of the interpolated point.
public double[]	Returns: interpolated secondary derivatives at the current interpolation date getInterpolatedSecondaryDerivatives(final int index of the secondary set, as returned by `ExpandableStatefulODE.addSecondaryEquations(SecondaryEquations)` secondaryStateIndex) Get the interpolated secondary derivatives corresponding to the secondary equations.
public double[]	Returns: interpolated secondary state at the current interpolation date getInterpolatedSecondaryState(final int index of the secondary set, as returned by `ExpandableStatefulODE.addSecondaryEquations(SecondaryEquations)` secondaryStateIndex) Get the interpolated secondary state corresponding to the secondary equations.
public double[]	Returns: state vector at time `getInterpolatedTime` getInterpolatedState() Get the state vector of the interpolated point.
public double	Returns: interpolation point time getInterpolatedTime() Get the time of the interpolated point.
public void	handleStep(final StepInterpolator interpolator for the last accepted step. interpolator, final boolean true if the step is the last one isLast) Implements org.apache.commons.math3.ode.sampling.StepHandler.handleStep. Handle the last accepted step.
public void	init(double start value of the independent time variable t0, double[] array containing the start value of the state vector y0, double target time for the integration t) Implements org.apache.commons.math3.ode.sampling.StepHandler.init. Initialize step handler at the start of an ODE integration.
private int	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 locatePoint(final double point to locate time, final StepInterpolator step interval interval) Compare a step interval and a double.
public void	setInterpolatedTime(final double time of the interpolated point time) Set the time of the interpolated point.

Inherited from java.lang.Object:: clone equals finalize getClass hashCode notify notifyAll toString wait wait wait

Field Detail

finalTime	back to summary
private double finalTime Final integration time.

forward	back to summary
private boolean forward Integration direction indicator.

index	back to summary
private int index Current interpolator index.

initialTime	back to summary
private double initialTime Initial integration time.

serialVersionUID	back to summary
private static final long serialVersionUID Serializable version identifier

steps	back to summary
private List<StepInterpolator> steps Steps table.

Constructor Detail

ContinuousOutputModel	back to summary
public ContinuousOutputModel() Simple constructor. Build an empty continuous output model.

Method Detail

append	back to summary
public void append(final ContinuousOutputModel model) throws MathIllegalArgumentException, MaxCountExceededException Append another model at the end of the instance. Parameters model:ContinuousOutputModel model to add at the end of the instance Exceptions MathIllegalArgumentException: if the model to append is not compatible with the instance (dimension of the state vector, propagation direction, hole between the dates) MaxCountExceededException: if the number of functions evaluations is exceeded during step finalization

append

back to summary

public void append(final ContinuousOutputModel model) throws MathIllegalArgumentException, MaxCountExceededException

Append another model at the end of the instance.

Parameters

model:ContinuousOutputModel: model to add at the end of the instance

Exceptions

MathIllegalArgumentException:: if the model to append is not compatible with the instance (dimension of the state vector, propagation direction, hole between the dates)
MaxCountExceededException:: if the number of functions evaluations is exceeded during step finalization

getFinalTime	back to summary
public double getFinalTime() Get the final integration time. Returns:double final integration time

getFinalTime

back to summary

public double getFinalTime()

Get the final integration time.

Returns:double: final integration time

getInitialTime	back to summary
public double getInitialTime() Get the initial integration time. Returns:double initial integration time

getInitialTime

back to summary

public double getInitialTime()

Get the initial integration time.

Returns:double: initial integration time

getInterpolatedDerivatives back to summary

getInterpolatedDerivatives	back to summary
public double[] getInterpolatedDerivatives() throws MaxCountExceededException Get the derivatives of the state vector of the interpolated point. The returned vector is a reference to a reused array, so it should not be modified and it should be copied if it needs to be preserved across several calls to the associated `setInterpolatedTime(double)` method. Returns:double[] derivatives of the state vector at time `getInterpolatedTime` Exceptions MaxCountExceededException: if the number of functions evaluations is exceeded Since 3.4 See Also `setInterpolatedTime(double)`, `getInterpolatedState()`, `getInterpolatedSecondaryState(int)`, `getInterpolatedSecondaryDerivatives(int)`

public double[] getInterpolatedDerivatives() throws MaxCountExceededException

Get the derivatives of the state vector of the interpolated point.

The returned vector is a reference to a reused array, so it should not be modified and it should be copied if it needs to be preserved across several calls to the associated setInterpolatedTime(double) method.

Returns:double[]

derivatives of the state vector at time getInterpolatedTime

Exceptions

MaxCountExceededException:: if the number of functions evaluations is exceeded

Since

3.4

getInterpolatedSecondaryDerivatives back to summary

getInterpolatedSecondaryDerivatives	back to summary
public double[] getInterpolatedSecondaryDerivatives(final int secondaryStateIndex) throws MaxCountExceededException Get the interpolated secondary derivatives corresponding to the secondary equations. The returned vector is a reference to a reused array, so it should not be modified and it should be copied if it needs to be preserved across several calls to the associated `setInterpolatedTime(double)` method. Parameters secondaryStateIndex:int index of the secondary set, as returned by `ExpandableStatefulODE.addSecondaryEquations(SecondaryEquations)` Returns:double[] interpolated secondary derivatives at the current interpolation date Exceptions MaxCountExceededException: if the number of functions evaluations is exceeded Since 3.4 See Also `setInterpolatedTime(double)`, `getInterpolatedState()`, `getInterpolatedDerivatives()`, `getInterpolatedSecondaryState(int)`

public double[] getInterpolatedSecondaryDerivatives(final int secondaryStateIndex) throws MaxCountExceededException

Get the interpolated secondary derivatives corresponding to the secondary equations.

Parameters

secondaryStateIndex:int: index of the secondary set, as returned by ExpandableStatefulODE.addSecondaryEquations(SecondaryEquations)

Returns:double[]

interpolated secondary derivatives at the current interpolation date

Exceptions

MaxCountExceededException:: if the number of functions evaluations is exceeded

Since

3.4

getInterpolatedSecondaryState back to summary

getInterpolatedSecondaryState	back to summary
public double[] getInterpolatedSecondaryState(final int secondaryStateIndex) throws MaxCountExceededException Get the interpolated secondary state corresponding to the secondary equations. The returned vector is a reference to a reused array, so it should not be modified and it should be copied if it needs to be preserved across several calls to the associated `setInterpolatedTime(double)` method. Parameters secondaryStateIndex:int index of the secondary set, as returned by `ExpandableStatefulODE.addSecondaryEquations(SecondaryEquations)` Returns:double[] interpolated secondary state at the current interpolation date Exceptions MaxCountExceededException: if the number of functions evaluations is exceeded Since 3.2 See Also `setInterpolatedTime(double)`, `getInterpolatedState()`, `getInterpolatedDerivatives()`, `getInterpolatedSecondaryDerivatives(int)`

public double[] getInterpolatedSecondaryState(final int secondaryStateIndex) throws MaxCountExceededException

Get the interpolated secondary state corresponding to the secondary equations.

Parameters

secondaryStateIndex:int: index of the secondary set, as returned by ExpandableStatefulODE.addSecondaryEquations(SecondaryEquations)

Returns:double[]

interpolated secondary state at the current interpolation date

Exceptions

MaxCountExceededException:: if the number of functions evaluations is exceeded

Since

3.2

getInterpolatedState back to summary

getInterpolatedState	back to summary
public double[] getInterpolatedState() throws MaxCountExceededException Get the state vector of the interpolated point. The returned vector is a reference to a reused array, so it should not be modified and it should be copied if it needs to be preserved across several calls to the associated `setInterpolatedTime(double)` method. Returns:double[] state vector at time `getInterpolatedTime` Exceptions MaxCountExceededException: if the number of functions evaluations is exceeded See Also `setInterpolatedTime(double)`, `getInterpolatedDerivatives()`, `getInterpolatedSecondaryState(int)`, `getInterpolatedSecondaryDerivatives(int)`

public double[] getInterpolatedState() throws MaxCountExceededException

Get the state vector of the interpolated point.

Returns:double[]

state vector at time getInterpolatedTime

Exceptions

MaxCountExceededException:: if the number of functions evaluations is exceeded

getInterpolatedTime back to summary

getInterpolatedTime	back to summary
public double getInterpolatedTime() Get the time of the interpolated point. If `setInterpolatedTime` has not been called, it returns the final integration time. Returns:double interpolation point time

public double getInterpolatedTime()

Get the time of the interpolated point. If setInterpolatedTime has not been called, it returns the final integration time.

Returns:double: interpolation point time

handleStep	back to summary
public void handleStep(final StepInterpolator interpolator, final boolean isLast) throws MaxCountExceededException Implements org.apache.commons.math3.ode.sampling.StepHandler.handleStep. Handle the last accepted step. A copy of the information provided by the last step is stored in the instance for later use. Parameters interpolator:StepInterpolator interpolator for the last accepted step. isLast:boolean true if the step is the last one Exceptions MaxCountExceededException: if the number of functions evaluations is exceeded during step finalization

handleStep

back to summary

public void handleStep(final StepInterpolator interpolator, final boolean isLast) throws MaxCountExceededException

Implements org.apache.commons.math3.ode.sampling.StepHandler.handleStep.

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

Parameters

interpolator:StepInterpolator: interpolator for the last accepted step.
isLast:boolean: true if the step is the last one

Exceptions

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

init	back to summary
public void init(double t0, double[] y0, double t) Implements org.apache.commons.math3.ode.sampling.StepHandler.init. Doc from org.apache.commons.math3.ode.sampling.StepHandler.init. 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. Parameters t0:double start value of the independent time variable y0:double[] array containing the start value of the state vector t:double target time for the integration

init

back to summary

public void init(double t0, double[] y0, double t)

Implements org.apache.commons.math3.ode.sampling.StepHandler.init.

Doc from org.apache.commons.math3.ode.sampling.StepHandler.init.

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.

Parameters

t0:double: start value of the independent time variable
y0:double[]: array containing the start value of the state vector
t:double: target time for the integration

locatePoint	back to summary
private int locatePoint(final double time, final StepInterpolator interval) Compare a step interval and a double. Parameters time:double point to locate interval:StepInterpolator step interval Returns:int -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

locatePoint

back to summary

private int locatePoint(final double time, final StepInterpolator interval)

Compare a step interval and a double.

Parameters

time:double: point to locate
interval:StepInterpolator: step interval

Returns:int

-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

setInterpolatedTime back to summary

setInterpolatedTime	back to summary
public void setInterpolatedTime(final double time) Set the time of the interpolated point. This method should not be called before the integration is over because some internal variables are set only once the last step has been handled. Setting the time outside of the integration interval is now allowed, but should be used with care since the accuracy of the interpolator will probably be very poor far from this interval. This allowance has been added to simplify implementation of search algorithms near the interval endpoints. Note that each time this method is called, the internal arrays returned in `getInterpolatedState()`, `getInterpolatedDerivatives()` and `getInterpolatedSecondaryState(int)` will be overwritten. So if their content must be preserved across several calls, user must copy them. Parameters time:double time of the interpolated point See Also `getInterpolatedState()`, `getInterpolatedDerivatives()`, `getInterpolatedSecondaryState(int)`

public void setInterpolatedTime(final double time)

Set the time of the interpolated point.

This method should not be called before the integration is over because some internal variables are set only once the last step has been handled.

Setting the time outside of the integration interval is now allowed, but should be used with care since the accuracy of the interpolator will probably be very poor far from this interval. This allowance has been added to simplify implementation of search algorithms near the interval endpoints.

Note that each time this method is called, the internal arrays returned in getInterpolatedState(), getInterpolatedDerivatives() and getInterpolatedSecondaryState(int) will be overwritten. So if their content must be preserved across several calls, user must copy them.

Parameters

time:double: time of the interpolated point

public Class ContinuousOutputModel

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail