Package org.opensourcephysics.numerics

Class ODEMultistepSolver

java.lang.Object

org.opensourcephysics.numerics.ODEMultistepSolver

All Implemented Interfaces:

ODEAdaptiveSolver, ODESolver

public class ODEMultistepSolver
extends Object
implements ODEAdaptiveSolver

ODEMultistepSolver performs multiple ODE steps so that a uniform step size is maintained.

Version:

1.0

Author:

Wolfgang Christian

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
protected final class	ODEMultistepSolver.InternalODE	A class that saves an internal state that may be different from the orginal ODE.

Field Summary

Fields

Modifier and Type	Field	Description
protected boolean	enableExceptions
protected int	err_code
protected String	err_msg
protected double	fixedStepSize
protected ODEMultistepSolver.InternalODE	internalODE
protected int	maxIterations
protected ODEAdaptiveSolver	odeEngine

Fields inherited from interface org.opensourcephysics.numerics.ODEAdaptiveSolver

BISECTION_EVENT_NOT_FOUND, DID_NOT_CONVERGE, NO_ERROR

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	ODEMultistepSolver()	Constructs a ODEMultistepSolver without an ODE so that a factory method can create a custom solver.
	ODEMultistepSolver(ODE ode)	Constructs an ODEMultiStep ODE solver for a system of ordinary differential equations.

Method Summary

Modifier and Type	Method	Description
void	enableRuntimeExpecptions(boolean enable)	Enables runtime exceptions if the solver does not converge.
int	getErrorCode()	Gets the error code.
double	getStepSize()	Gets the step size.
double	getTolerance()	Gets the tolerance of the adaptive ODE solver.
void	initialize(double stepSize)	Initializes the ODE solver.
static ODEAdaptiveSolver	MultistepRK45(ODE ode)	A factory method that creates a multisetp solver using the RK45 engine.
void	setMaximumNumberOfErrorMessages(int n)	Sets the number of error messages if ODE solver did not converge.
void	setMaxIterations(int n)	Sets the maximum number of iterations.
protected ODEMultistepSolver.InternalODE	setODE(ODE ode)	Sets the ODE for this solver.
void	setStepSize(double stepSize)	Sets the fixed step size.
void	setTolerance(double tol)	Sets the tolerance of the adaptive ODE solver.
double	step()	Steps (advances) the differential equations by the stepSize.

Methods inherited from class java.lang.Object

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

Field Details

err_code

protected int err_code

maxIterations

protected int maxIterations

enableExceptions

protected boolean enableExceptions

err_msg

protected String err_msg

odeEngine

protected ODEAdaptiveSolver odeEngine

fixedStepSize

protected double fixedStepSize

internalODE

protected ODEMultistepSolver.InternalODE internalODE

Constructor Details

ODEMultistepSolver

public ODEMultistepSolver(ODE ode)

Constructs an ODEMultiStep ODE solver for a system of ordinary differential equations. The default ODESolver is DormandPrince45. Other solvers can be selected using factory methods.

Parameters:

ode -

ODEMultistepSolver

protected ODEMultistepSolver()

Constructs a ODEMultistepSolver without an ODE so that a factory method can create a custom solver.

Method Details

setODE

protected ODEMultistepSolver.InternalODE setODE(ODE ode)

Sets the ODE for this solver.

Parameters:

ode - ODE

Returns:

MyODE

MultistepRK45

public static ODEAdaptiveSolver MultistepRK45(ODE ode)

A factory method that creates a multisetp solver using the RK45 engine.

Parameters:

ode - ODE

Returns:

ODESolver

enableRuntimeExpecptions

public void enableRuntimeExpecptions(boolean enable)

Enables runtime exceptions if the solver does not converge.

Parameters:

enable - boolean

setMaxIterations

public void setMaxIterations(int n)

Sets the maximum number of iterations.

Parameters:

n - maximum

setTolerance

public void setTolerance(double tol)

Sets the tolerance of the adaptive ODE solver.

Specified by:

setTolerance in interface ODEAdaptiveSolver

Parameters:

tol - the tolerance

getTolerance

public double getTolerance()

Gets the tolerance of the adaptive ODE solver.

Specified by:

getTolerance in interface ODEAdaptiveSolver

Returns:

getErrorCode

public int getErrorCode()

Gets the error code. Error codes: ODEAdaptiveSolver.NO_ERROR ODEAdaptiveSolver.DID_NOT_CONVERGE ODEAdaptiveSolver.BISECTION_EVENT_NOT_FOUND=2;

Specified by:

getErrorCode in interface ODEAdaptiveSolver

Returns:

int

step

public double step()

Steps (advances) the differential equations by the stepSize. The ODESolver invokes the ODE's getRate method to obtain the initial state of the system. The ODESolver then advances the solution and copies the new state into the state array at the end of the solution step if desired tolerance was reached.

Specified by:

step in interface ODESolver

Returns:

the actual step

initialize

public void initialize(double stepSize)

Initializes the ODE solver. Temporary arrays may be allocated within the ODE solver.

Specified by:

initialize in interface ODESolver

Parameters:

stepSize -

setStepSize

public void setStepSize(double stepSize)

Sets the fixed step size. Multi-step solvers will perform one or more internal steps in order to perform a step with the given size.

Specified by:

setStepSize in interface ODESolver

Parameters:

stepSize -

setMaximumNumberOfErrorMessages

public void setMaximumNumberOfErrorMessages(int n)

Sets the number of error messages if ODE solver did not converge.

Parameters:

n - int

getStepSize

public double getStepSize()

Gets the step size. The step size is the fixed step size, not the size of the ODEAdaptiveSolver steps that are combined into a single step.

Specified by:

getStepSize in interface ODESolver

Returns:

the step size