fr.cnes.sirius.patrius.math.ode.nonstiff.cowell

Class CowellIntegrator

java.lang.Object

java.util.Observable

fr.cnes.sirius.patrius.math.ode.AbstractIntegrator

fr.cnes.sirius.patrius.math.ode.nonstiff.cowell.CowellIntegrator

All Implemented Interfaces:

FirstOrderIntegrator, ODEIntegrator

public class CowellIntegrator
extends AbstractIntegrator

This class implements a 2nd order Cowell integrator.

The algorithms used in this code are explained in "A Variable-Step Double-Integration Multi-Step Integrator" by Matthew M. Berry. PhD Dissertation, Virginia Polytechnic Institute and State University, Blacksburg, VA. April 2004.

This integrator is suited only for cartesian orbit integration (including partial derivatives such as mass equation and state transition matrix).

This integrator requires a SecondOrderStateMapper in order to perform first order state from/to second order state conversion. This conversion is necessary as the integrator only deals with second order state while other PATRIUS features such as interpolation, event detection and any other AbstractIntegrator-related features deals only with first order state vectors. This mapper is set through method setMapper(SecondOrderStateMapper).

For best performances, the integrator parameters should be:

• Order: 9
• Tolerances: between 1E-10 and 1E-12

Since:

4.6

Author:

Emmanuel Bignon

See Also:

SecondOrderStateMapper

Field Summary

Fields

Modifier and Type	Field and Description
static int	MAX_STANDARD_ORDER Maximum order for standard formulas.

Fields inherited from class fr.cnes.sirius.patrius.math.ode.AbstractIntegrator

isLastStep, lastStepHandle, resetOccurred, stepHandlers, stepSize, stepStart

Constructor Summary

Constructors

Constructor and Description
CowellIntegrator(int order, double absTol, double relTol) Constructor.

Method Summary

Modifier and Type	Method and Description
protected fr.cnes.sirius.patrius.math.ode.nonstiff.cowell.State	getCurrentState() Returns integrator current state.
SecondOrderStateMapper	getMapper() Returns the second order / first order state mapper.
int	getOrder() Returns integrator order.
protected fr.cnes.sirius.patrius.math.ode.nonstiff.cowell.State	getPreviousState() Returns integrator previous state.
protected fr.cnes.sirius.patrius.math.ode.nonstiff.cowell.Support	getSupport() Returns the integration support.
void	integrate(ExpandableStatefulODE equations, double t) Integrate a set of differential equations up to the given time.
void	setMapper(SecondOrderStateMapper mapper) Set second order / first order state mapper.

Methods inherited from class fr.cnes.sirius.patrius.math.ode.AbstractIntegrator

acceptStep, addEventHandler, addEventHandler, addStepHandler, avoidOvershoot, clearEventHandlers, clearStepHandlers, computeDerivatives, getCurrentSignedStepsize, getCurrentStepStart, getEvaluations, getEventHandlers, getMaxEvaluations, getName, getStepHandlers, handleLastStep, initIntegration, integrate, removeEventState, sanityChecks, setEquations, setMaxEvaluations, setStateInitialized

Methods inherited from class java.util.Observable

addObserver, clearChanged, countObservers, deleteObserver, deleteObservers, hasChanged, notifyObservers, notifyObservers, setChanged

Methods inherited from class java.lang.Object

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

Field Detail

MAX_STANDARD_ORDER

public static final int MAX_STANDARD_ORDER

Maximum order for standard formulas.

See Also:

Constant Field Values

Constructor Detail

CowellIntegrator

public CowellIntegrator(int order,
                        double absTol,
                        double relTol)

Constructor.

Parameters:

order - integrator order (<= 20)

absTol - absolute tolerance

relTol - relative tolerance

Method Detail

integrate

public void integrate(ExpandableStatefulODE equations,
                      double t)

Integrate a set of differential equations up to the given time.

This method solves an Initial Value Problem (IVP).

The set of differential equations is composed of a main set, which can be extended by some sets of secondary equations. The set of equations must be already set up with initial time and partial states. At integration completion, the final time and partial states will be available in the same object.

Since this method stores some internal state variables made available in its public interface during integration (AbstractIntegrator.getCurrentSignedStepsize()), it is not thread-safe.

Warning:

• Equations should both implements FirstOrderDifferentialEquations and SecondOrderDifferentialEquations.
• This integrator is suitable only for cartesian orbit integration and state vector should hence be of the form: [x y z vx vy vz...] (... being for additional states).

Specified by:

integrate in class AbstractIntegrator

Parameters:

equations - complete set of differential equations to integrate

t - target time for the integration (can be set to a value smaller than t0 for backward integration)

getOrder

public int getOrder()

Returns integrator order.

Returns:

integrator order

getSupport

protected fr.cnes.sirius.patrius.math.ode.nonstiff.cowell.Support getSupport()

Returns the integration support.

Returns:

the integration support

getPreviousState

protected fr.cnes.sirius.patrius.math.ode.nonstiff.cowell.State getPreviousState()

Returns integrator previous state.

Returns:

integrator previous state

getCurrentState

protected fr.cnes.sirius.patrius.math.ode.nonstiff.cowell.State getCurrentState()

Returns integrator current state.

Returns:

integrator current state

setMapper

public void setMapper(SecondOrderStateMapper mapper)

Set second order / first order state mapper.

Parameters:

mapper - second order / first order state mapper

getMapper

public SecondOrderStateMapper getMapper()

Returns the second order / first order state mapper.

Returns:

the second order / first order state mapper