Class AdaptiveSwimUtilities

java.lang.Object

cnuphys.adaptiveSwim.AdaptiveSwimUtilities

public class AdaptiveSwimUtilities
extends Object

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static enum	AdaptiveSwimUtilities.DebugLevel

Field Summary

Fields

Modifier and Type	Field	Description
static int	MAX_NUMSTEP
static final double	MIN_STEPSIZE

Constructor Summary

Constructors

Constructor	Description
AdaptiveSwimUtilities()

Method Summary

Modifier and Type	Method	Description
static int	driver(double h, IDerivative deriv, IAdaptiveStopper stopper, IAdaptiveAdvance advancer, double eps, double[] uf)	Basic adaptive step size driver that tries to integrate from s = 0 to s = sf, where sf is in the stopper object.
static int	getSector(double phi)	Get the sector [1..6] from the phi value
static void	setDebugLevel(AdaptiveSwimUtilities.DebugLevel level)	Set the debug level
static void	setMaxNumberSteps(int maxSteps)	Set the maximum number of steps beyond which an error occurs
static void	singleButcherStep(double s, double[] u, double[] du, double h, IDerivative deriv, double[] uf, double[] error, ButcherTableau tableau)	Take a single step using a Butcher tableau
static void	singleRK4Step(double s, double[] u, double[] du, double h, IDerivative deriv, double[] uf)	Take a single step using basic fourth order RK

Methods inherited from class Object

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

Field Details

MIN_STEPSIZE

public static final double MIN_STEPSIZE

See Also:

• Constant Field Values

MAX_NUMSTEP

public static int MAX_NUMSTEP

Constructor Details

AdaptiveSwimUtilities

public AdaptiveSwimUtilities()

Method Details

driver

public static int driver(double h,
 IDerivative deriv,
 IAdaptiveStopper stopper,
 IAdaptiveAdvance advancer,
 double eps,
 double[] uf)
                  throws AdaptiveSwimException

Basic adaptive step size driver that tries to integrate from s = 0 to s = sf, where sf is in the stopper object. Often this will terminate because the stopper stops the integration before sf is reached.

Parameters:

h - the step size at the start

deriv - the derivative computer (interface). This is where the problem specificity resides.

stopper - will be used to exit the integration early because some condition has been reached.

advancer - takes the next single step

eps - tolerance (e.g., 1.0e-6)

uf - will hold final state vector

Returns:

the number of steps used.

Throws:

AdaptiveSwimException

singleRK4Step

public static void singleRK4Step(double s,
 double[] u,
 double[] du,
 double h,
 IDerivative deriv,
 double[] uf)

Take a single step using basic fourth order RK

Parameters:

s - the independent variable

u - the current state vector

du - the current derivatives

h - the step size

deriv - can compute the rhs of the diffy q

uf - the state vector after the step

singleButcherStep

public static void singleButcherStep(double s,
 double[] u,
 double[] du,
 double h,
 IDerivative deriv,
 double[] uf,
 double[] error,
 ButcherTableau tableau)

Take a single step using a Butcher tableau

Parameters:

s - the independent variable

u - the current state vector

du - the current derivatives

h - the step size

deriv - can compute the rhs of the diffy q

uf - the state vector after the step (output)

error - the error estimate (output)

tableau - the Butcher tableau

setDebugLevel

public static void setDebugLevel(AdaptiveSwimUtilities.DebugLevel level)

Set the debug level

Parameters:

level - the new debug level

setMaxNumberSteps

public static void setMaxNumberSteps(int maxSteps)

Set the maximum number of steps beyond which an error occurs

Parameters:

maxSteps - the maximum number of steps. Default is 2000.

getSector

public static int getSector(double phi)

Get the sector [1..6] from the phi value

Parameters:

phi - the value of phi in degrees

Returns:

the sector [1..6]