org.apache.commons.math.ode.sampling

Class StepNormalizer

java.lang.Object

org.apache.commons.math.ode.sampling.StepNormalizer

All Implemented Interfaces:

StepHandler

public class StepNormalizer
extends java.lang.Object
implements StepHandler

This class wraps an object implementing FixedStepHandler into a StepHandler.

This wrapper allows to use fixed step handlers with general integrators which cannot guaranty their integration steps will remain constant and therefore only accept general step handlers.

The stepsize used is selected at construction time. The handleStep method of the underlying FixedStepHandler object is called at the beginning time of the integration t0 and also at times t0+h, t0+2h, ... If the integration range is an integer multiple of the stepsize, then the last point handled will be the endpoint of the integration tend, if not, the last point will belong to the interval [tend - h ; tend].

There is no constraint on the integrator, it can use any timestep it needs (time steps longer or shorter than the fixed time step and non-integer ratios are all allowed).

Since:

1.2

See Also:

StepHandler, FixedStepHandler

Constructor Summary

Constructors

Constructor and Description
StepNormalizer(double h, FixedStepHandler handler) Simple constructor.

Method Summary

Modifier and Type	Method and Description
void	handleStep(StepInterpolator interpolator, boolean isLast) Handle the last accepted step
boolean	requiresDenseOutput() Determines whether this handler needs dense output.
void	reset() Reset the step handler.

Methods inherited from class java.lang.Object

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

Constructor Detail

StepNormalizer

public StepNormalizer(double h,
                      FixedStepHandler handler)

Simple constructor.

Parameters:

h - fixed time step (sign is not used)

handler - fixed time step handler to wrap

Method Detail

requiresDenseOutput

public boolean requiresDenseOutput()

Determines whether this handler needs dense output. This handler needs dense output in order to provide data at regularly spaced steps regardless of the steps the integrator uses, so this method always returns true.

Specified by:

requiresDenseOutput in interface StepHandler

Returns:

always true

reset

public void reset()

Reset the step handler. Initialize the internal data as required before the first step is handled.

Specified by:

reset in interface StepHandler

handleStep

public void handleStep(StepInterpolator interpolator,
                       boolean isLast)
                throws DerivativeException

Handle the last accepted step

Specified by:

handleStep in interface StepHandler

Parameters:

interpolator - interpolator for the last accepted step. For efficiency purposes, the various integrators reuse the same object on each call, so if the instance wants to keep it across all calls (for example to provide at the end of the integration a continuous model valid throughout the integration range), it should build a local copy using the clone method and store this copy.

isLast - true if the step is the last one

Throws:

DerivativeException - this exception is propagated to the caller if the underlying user function triggers one