Package org.hipparchus.ode.nonstiff

Class FixedStepRungeKuttaFieldIntegrator<T extends CalculusFieldElement<T>>

java.lang.Object

org.hipparchus.ode.AbstractFieldIntegrator<T>

org.hipparchus.ode.nonstiff.FixedStepRungeKuttaFieldIntegrator<T>

Type Parameters:

T - the type of the field elements

All Implemented Interfaces:

FieldODEIntegrator<T>, FieldButcherArrayProvider<T>, FieldExplicitRungeKuttaIntegrator<T>

Direct Known Subclasses:

ClassicalRungeKuttaFieldIntegrator, EulerFieldIntegrator, GillFieldIntegrator, LutherFieldIntegrator, MidpointFieldIntegrator, ThreeEighthesFieldIntegrator

public abstract class FixedStepRungeKuttaFieldIntegrator<T extends CalculusFieldElement<T>>
extends AbstractFieldIntegrator<T>
implements FieldExplicitRungeKuttaIntegrator<T>

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
 

See Also:

• EulerFieldIntegrator
• ClassicalRungeKuttaFieldIntegrator
• GillFieldIntegrator
• MidpointFieldIntegrator

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	FixedStepRungeKuttaFieldIntegrator(Field<T> field, String name, T step)	Simple constructor.

Method Summary

Modifier and Type	Method	Description
protected abstract RungeKuttaFieldStateInterpolator<T>	createInterpolator(boolean forward, T[][] yDotK, FieldODEStateAndDerivative<T> globalPreviousState, FieldODEStateAndDerivative<T> globalCurrentState, FieldEquationsMapper<T> mapper)	Create an interpolator.
T	getDefaultStep()	Getter for the default, positive step-size assigned at constructor level.
int	getNumberOfStages()	Getter for the number of stages corresponding to the Butcher array.
protected FieldODEStateAndDerivative<T>	initIntegration(FieldExpandableODE<T> eqn, FieldODEState<T> s0, T t)	Prepare the start of an integration.
FieldODEStateAndDerivative<T>	integrate(FieldExpandableODE<T> equations, FieldODEState<T> initialState, T finalTime)	Integrate the differential equations up to the given time.
boolean	isUsingFieldCoefficients()	Getter for the flag between real or Field coefficients in the Butcher array.
void	setUsingFieldCoefficients(boolean usingFieldCoefficients)	Setter for the flag between real or Field coefficients in the Butcher array.

Methods inherited from class org.hipparchus.ode.AbstractFieldIntegrator

acceptStep, addEventDetector, addStepEndHandler, addStepHandler, clearEventDetectors, clearStepEndHandlers, clearStepHandlers, computeDerivatives, getCurrentSignedStepsize, getEquations, getEvaluations, getEvaluationsCounter, getEventDetectors, getField, getMaxEvaluations, getName, getStepEndHandlers, getStepHandlers, getStepSize, getStepStart, incrementEvaluations, isLastStep, resetOccurred, sanityChecks, setIsLastStep, setMaxEvaluations, setStateInitialized, setStepSize, setStepStart

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.hipparchus.ode.nonstiff.FieldButcherArrayProvider

getA, getB, getC

Methods inherited from interface org.hipparchus.ode.nonstiff.FieldExplicitRungeKuttaIntegrator

getRealA, getRealB, getRealC, singleStep

Methods inherited from interface org.hipparchus.ode.FieldODEIntegrator

addEventDetector, addStepEndHandler, addStepHandler, clearEventDetectors, clearStepEndHandlers, clearStepHandlers, getCurrentSignedStepsize, getEvaluations, getEventDetectors, getMaxEvaluations, getName, getStepEndHandlers, getStepHandlers, getStepStart, setMaxEvaluations

Constructor Details

FixedStepRungeKuttaFieldIntegrator

protected FixedStepRungeKuttaFieldIntegrator(Field<T> field,
 String name,
 T step)

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

Parameters:

field - field to which the time and state vector elements belong

name - name of the method

step - integration step

Method Details

getDefaultStep

public T getDefaultStep()

Getter for the default, positive step-size assigned at constructor level.

Returns:

step

setUsingFieldCoefficients

public void setUsingFieldCoefficients(boolean usingFieldCoefficients)

Setter for the flag between real or Field coefficients in the Butcher array.

Parameters:

usingFieldCoefficients - new value for flag

isUsingFieldCoefficients

public boolean isUsingFieldCoefficients()

Getter for the flag between real or Field coefficients in the Butcher array.

Specified by:

isUsingFieldCoefficients in interface FieldExplicitRungeKuttaIntegrator<T extends CalculusFieldElement<T>>

Returns:

flag

getNumberOfStages

public int getNumberOfStages()

Getter for the number of stages corresponding to the Butcher array.

Specified by:

getNumberOfStages in interface FieldExplicitRungeKuttaIntegrator<T extends CalculusFieldElement<T>>

Returns:

number of stages

createInterpolator

protected abstract RungeKuttaFieldStateInterpolator<T> createInterpolator(boolean forward,
 T[][] yDotK,
 FieldODEStateAndDerivative<T> globalPreviousState,
 FieldODEStateAndDerivative<T> globalCurrentState,
 FieldEquationsMapper<T> mapper)

Create an interpolator.

Parameters:

forward - integration direction indicator

yDotK - slopes at the intermediate points

globalPreviousState - start of the global step

globalCurrentState - end of the global step

mapper - equations mapper for the all equations

Returns:

external weights for the high order method from Butcher array

initIntegration

protected FieldODEStateAndDerivative<T> initIntegration(FieldExpandableODE<T> eqn,
 FieldODEState<T> s0,
 T t)

Prepare the start of an integration.

Overrides:

initIntegration in class AbstractFieldIntegrator<T extends CalculusFieldElement<T>>

Parameters:

eqn - equations to integrate

s0 - initial state vector

t - target time for the integration

Returns:

initial state with derivatives added

integrate

public FieldODEStateAndDerivative<T> integrate(FieldExpandableODE<T> equations,
 FieldODEState<T> initialState,
 T finalTime)
                                        throws MathIllegalArgumentException,
MathIllegalStateException

Integrate the differential equations up to the given time.

This method solves an Initial Value Problem (IVP).

Since this method stores some internal state variables made available in its public interface during integration (FieldODEIntegrator.getCurrentSignedStepsize()), it is not thread-safe.

Specified by:

integrate in interface FieldODEIntegrator<T extends CalculusFieldElement<T>>

Parameters:

equations - differential equations to integrate

initialState - initial state (time, primary and secondary state vectors)

finalTime - target time for the integration (can be set to a value smaller than t0 for backward integration)

Returns:

final state, its time will be the same as finalTime if integration reached its target, but may be different if some FieldODEEventHandler stops it at some point.

Throws:

MathIllegalArgumentException - if integration step is too small

MathIllegalArgumentException - if the location of an event cannot be bracketed

MathIllegalStateException - if the number of functions evaluations is exceeded