Package org.hipparchus.ode

Class ExpandableODE

java.lang.Object

org.hipparchus.ode.ExpandableODE

public class ExpandableODE
extends Object

This class represents a combined set of first order differential equations, with at least a primary set of equations expandable by some sets of secondary equations.

One typical use case is the computation of the Jacobian matrix for some ODE. In this case, the primary set of equations corresponds to the raw ODE, and we add to this set another bunch of secondary equations which represent the Jacobian matrix of the primary set.

We want the integrator to use only the primary set to estimate the errors and hence the step sizes. It should not use the secondary equations in this computation. The integrator will be able to know where the primary set ends and so where the secondary sets begin.

See Also:

OrdinaryDifferentialEquation, VariationalEquation

Constructor Summary

Constructors

Constructor	Description
ExpandableODE(OrdinaryDifferentialEquation primary)	Build an expandable set from its primary ODE set.

Method Summary

Modifier and Type	Method	Description
int	addSecondaryEquations(SecondaryODE secondary)	Add a set of secondary equations to be integrated along with the primary set.
double[]	computeDerivatives(double t, double[] y)	Get the current time derivative of the complete state vector.
EquationsMapper	getMapper()	Get the mapper for the set of equations.
OrdinaryDifferentialEquation	getPrimary()	Get the primary set of differential equations to be integrated.
void	init(ODEState s0, double finalTime)	Initialize equations 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

ExpandableODE

public ExpandableODE(OrdinaryDifferentialEquation primary)

Build an expandable set from its primary ODE set.

Parameters:

primary - the primary set of differential equations to be integrated.

Method Detail

getPrimary

public OrdinaryDifferentialEquation getPrimary()

Get the primary set of differential equations to be integrated.

Returns:

primary set of differential equations to be integrated

getMapper

public EquationsMapper getMapper()

Get the mapper for the set of equations.

Returns:

mapper for the set of equations

addSecondaryEquations

public int addSecondaryEquations(SecondaryODE secondary)

Add a set of secondary equations to be integrated along with the primary set.

Parameters:

secondary - secondary equations set

Returns:

index of the secondary equation in the expanded state, to be used as the parameter to FieldODEState.getSecondaryState(int) and FieldODEStateAndDerivative.getSecondaryDerivative(int) (beware index 0 corresponds to primary state, secondary states start at 1)

init

public void init(ODEState s0,
                 double finalTime)

Initialize equations at the start of an ODE integration.

Parameters:

s0 - state at integration start

finalTime - target time for the integration

Throws:

MathIllegalStateException - if the number of functions evaluations is exceeded

MathIllegalArgumentException - if arrays dimensions do not match equations settings

computeDerivatives

public double[] computeDerivatives(double t,
                                   double[] y)
                            throws MathIllegalArgumentException,
                                   MathIllegalStateException

Get the current time derivative of the complete state vector.

Parameters:

t - current value of the independent time variable

y - array containing the current value of the complete state vector

Returns:

time derivative of the complete state vector

Throws:

MathIllegalStateException - if the number of functions evaluations is exceeded

MathIllegalArgumentException - if arrays dimensions do not match equations settings