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:

  • Constructor Details

    • 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 Details

    • 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