org.hipparchus.ode

## Class 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 DenseOutputModel 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 DenseOutputModel 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).

ODEStepHandler, ODEStateInterpolator, Serialized Form
• ### Constructor Summary

Constructors
Constructor and Description
DenseOutputModel()
Simple constructor.
• ### Method Summary

All Methods
Modifier and Type Method and Description
void append(DenseOutputModel model)
Append another model at the end of the instance.
void finish(ODEStateAndDerivative finalState)
Finalize integration.
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)
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)
Handle the last accepted step.
Specified by:
handleStep in interface ODEStepHandler
Parameters:
interpolator - interpolator for the last accepted step
• #### finish

public void finish(ODEStateAndDerivative finalState)
Finalize integration.
Specified by:
finish in interface ODEStepHandler
Parameters:
finalState - state at integration end
• #### 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