org.hipparchus.ode

Class DenseOutputModel

java.lang.Object

org.hipparchus.ode.DenseOutputModel

All Implemented Interfaces:

Serializable, ODEStepHandler

Direct Known Subclasses:

ContinuousOutputModel

public class DenseOutputModel
extends Object
implements ODEStepHandler, Serializable

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 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).

See Also:

ODEStepHandler, ODEStateInterpolator, Serialized Form

Constructor Summary

Constructors

Constructor and Description
DenseOutputModel() Simple constructor.

Method Summary

Modifier and Type	Method and Description
void	append(DenseOutputModel model) Append another model at the end of the instance.
double	getFinalTime() Get the final integration time.
double	getInitialTime() Get the initial integration time.
ODEStateAndDerivative	getInterpolatedState(double time) Get the state at interpolated time.
void	handleStep(ODEStateInterpolator interpolator, boolean isLast) Handle the last accepted step.
void	init(ODEStateAndDerivative initialState, double targetTime) Initialize step handler at the start of an ODE integration.

Methods inherited from class java.lang.Object

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

Constructor Detail

DenseOutputModel

public DenseOutputModel()

Simple constructor. Build an empty continuous output model.

Method Detail

append

public void append(DenseOutputModel model)
            throws MathIllegalArgumentException,
                   MathIllegalStateException

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)

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

init

public void init(ODEStateAndDerivative initialState,
                 double targetTime)

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.

The default implementation does nothing

Specified by:

init in interface ODEStepHandler

Parameters:

initialState - initial time, state vector and derivative

targetTime - target time for the integration

handleStep

public void handleStep(ODEStateInterpolator interpolator,
                       boolean isLast)
                throws MathIllegalStateException

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 ODEStepHandler

Parameters:

interpolator - interpolator for the last accepted step.

isLast - true if the step is the last one

Throws:

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

getInitialTime

public double getInitialTime()

Get the initial integration time.

Returns:

initial integration time

getFinalTime

public double getFinalTime()

Get the final integration time.

Returns:

final integration time

getInterpolatedState

public ODEStateAndDerivative getInterpolatedState(double time)

Get the state at interpolated time.

Parameters:

time - time of the interpolated point

Returns:

state at interpolated time