org.apache.commons.math.ode.nonstiff
Class RungeKuttaIntegrator

java.lang.Object
  org.apache.commons.math.ode.AbstractIntegrator
      org.apache.commons.math.ode.nonstiff.RungeKuttaIntegrator

All Implemented Interfaces:

FirstOrderIntegrator, ODEIntegrator

Direct Known Subclasses:

ClassicalRungeKuttaIntegrator, EulerIntegrator, GillIntegrator, MidpointIntegrator, ThreeEighthesIntegrator

public abstract class RungeKuttaIntegrator
extends AbstractIntegrator

This class implements the common part of all fixed step Runge-Kutta integrators for Ordinary Differential Equations.

These methods are explicit Runge-Kutta methods, their Butcher arrays are as follows :

    0  |
   c2  | a21
   c3  | a31  a32
   ... |        ...
   cs  | as1  as2  ...  ass-1
       |--------------------------
       |  b1   b2  ...   bs-1  bs
 

Since:

1.2

Version:

$Id: RungeKuttaIntegrator.java 1176734 2011-09-28 05:56:42Z luc $

See Also:

EulerIntegrator, ClassicalRungeKuttaIntegrator, GillIntegrator, MidpointIntegrator

Field Summary

Fields inherited from class org.apache.commons.math.ode.AbstractIntegrator

isLastStep, resetOccurred, stepHandlers, stepSize, stepStart

Constructor Summary

protected

RungeKuttaIntegrator(java.lang.String name, double[] c, double[][] a, double[] b, org.apache.commons.math.ode.nonstiff.RungeKuttaStepInterpolator prototype, double step) Simple constructor.

Method Summary

void	integrate(ExpandableStatefulODE equations, double t) Integrate a set of differential equations up to the given time.

Methods inherited from class org.apache.commons.math.ode.AbstractIntegrator

acceptStep, addEventHandler, addEventHandler, addStepHandler, clearEventHandlers, clearStepHandlers, computeDerivatives, getCurrentSignedStepsize, getCurrentStepStart, getEvaluations, getEventHandlers, getMaxEvaluations, getName, getStepHandlers, integrate, resetEvaluations, sanityChecks, setEquations, setMaxEvaluations, setStateInitialized

Methods inherited from class java.lang.Object

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

Constructor Detail

RungeKuttaIntegrator

protected RungeKuttaIntegrator(java.lang.String name,
                               double[] c,
                               double[][] a,
                               double[] b,
                               org.apache.commons.math.ode.nonstiff.RungeKuttaStepInterpolator prototype,
                               double step)

Simple constructor. Build a Runge-Kutta integrator with the given step. The default step handler does nothing.

Parameters:

name - name of the method

c - time steps from Butcher array (without the first zero)

a - internal weights from Butcher array (without the first empty row)

b - propagation weights for the high order method from Butcher array

prototype - prototype of the step interpolator to use

step - integration step

Method Detail

integrate

public void integrate(ExpandableStatefulODE equations,
                      double t)
               throws MathIllegalStateException,
                      MathIllegalArgumentException

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.

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)

Throws:

MathIllegalStateException - if the integrator cannot perform integration

MathIllegalArgumentException - if integration parameters are wrong (typically too small integration span)