org.hipparchus.ode

## Class 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.

OrdinaryDifferentialEquation, VariationalEquation
• ### Constructor Summary

Constructors
Constructor and Description
ExpandableODE(OrdinaryDifferentialEquation primary)
Build an expandable set from its primary ODE set.
• ### Method Summary

All Methods
Modifier and Type Method and 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 primaryset 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 primaryset 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
• #### 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