jvx.numeric
Class PnEnergy

java.lang.Object
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  +--jv.object.PsObject
        |
        +--jvx.numeric.PnFunction
              |
              +--jvx.numeric.PnEnergy

All Implemented Interfaces:

java.lang.Cloneable, PsUpdateIf, java.io.Serializable

Direct Known Subclasses:

PnAreaEnergy, PnConfEnergy, PnDiriEnergy, PnSpringEnergy

public abstract class PnEnergy

extends PnFunction

Energy functional on triangulated surfaces including gradient and hessian computations.

Surface must contain all boundary information. Domain is only used by some energy functionals to compute the stiffness matrix.

Version:

04.01.01, 2.50 revised (kp) Domain geometry may be missing.
06.06.99, 2.00 revised (kp) Extracted from merged PnAreaEnergy and PnDirichletEnergy.
21.04.99, 1.00 created (kp) from PnDiriEnergy.

Author:

Konrad Polthier

See Also:

Serialized Form

Fields inherited from class jv.object.PsObject

HAS_CONFIG_PANEL, HAS_INFO_PANEL, HAS_MATERIAL_PANEL, HAS_TEXTURE_PANEL, INSPECTOR_INFO, INSPECTOR_INFO_EXT, IS_DELETED, IS_FIXED, IS_SELECTED, IS_USED, NUM_TAGS

Constructor Summary

PnEnergy()

Method Summary

double	eval(PdVector coord) Compute Area energy of a coord vector using the stiffness matrix of a PnArea instance.
PdVector	evalGradient(PdVector coord, PdVector gradient) Evaluate Area gradient of a coord vector using the stiffness matrix of a PnArea instance.
abstract PdMatrix	evalHessian(PdMatrix hessian) Subclass must supply method to compute hessian of energy.
int	getNumOfVariables() Get number of free variables of energy.
PdVector[]	getSpectrum(PdVector eValue, PdVector[] eVector) Compute eigenvalues and eigenvectors of normalized hessian.
boolean	getZeroGradientAtBounds()
void	init() If instance has missing name then assign default name 'object_NUMBER' where number is the total number of already created instances.
void	initSurface(PgElementSet domain, PgElementSet surface) Method called from energyMinimizer.minimizeStep() to update the stiffness matrix after conjugate gradient method has returned.
boolean	setSurface(PgElementSet domain, PgElementSet surface) Set domain and surface, and initialize energy structure.
void	setZeroGradientAtBounds(boolean flag) Constraints the gradient at the boundary to zero or makes it free again.
void	testEigenvalues()

Methods inherited from class jvx.numeric.PnFunction

enableEvaluation, isEvaluable

Methods inherited from class jv.object.PsObject

addInspector, addUpdateListener, assureInspector, clearTag, clone, clone, clone, copy, getFather, getInfoPanel, getInspector, getName, getNumObjects, hasInspector, hasTag, hasUpdateListener, instanceOf, instanceOf, removeInspector, removeUpdateListener, setName, setParent, setTag, toString, update, updatePanels

Methods inherited from class java.lang.Object

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

Constructor Detail

PnEnergy

public PnEnergy()

Method Detail

init

public void init()

Description copied from class: PsObject

If instance has missing name then assign default name 'object_NUMBER' where number is the total number of already created instances.

Overrides:

init in class PsObject

initSurface

public void initSurface(PgElementSet domain,
                        PgElementSet surface)

Method called from energyMinimizer.minimizeStep() to update the stiffness matrix after conjugate gradient method has returned. E.g. PnDiriEnergy should copy surface into domain if in iteration mode i.e. if dimension of domain and surface are equal.

getNumOfVariables

public int getNumOfVariables()

Get number of free variables of energy.

Overrides:

getNumOfVariables in class PnFunction

setSurface

public boolean setSurface(PgElementSet domain,
                          PgElementSet surface)

Set domain and surface, and initialize energy structure. Method is called from outside whenever domain or surface has been updated. Domain argument maybe null.

eval

public double eval(PdVector coord)

Compute Area energy of a coord vector using the stiffness matrix of a PnArea instance. Method uses the array m_store of PnArea for intermediate storage and modifies its entries.

Overrides:

eval in class PnFunction

Parameters:

coord - Coordinate vector with list of doubles

Returns:

double Energy of coordinate vector

See Also:

vgp.discrete.harmonic.PnAreaEnergy

setZeroGradientAtBounds

public void setZeroGradientAtBounds(boolean flag)

Constraints the gradient at the boundary to zero or makes it free again. Default is true, i.e. constrained gradient.

getZeroGradientAtBounds

public boolean getZeroGradientAtBounds()

See Also:

setZeroGradientAtBounds(boolean)

evalGradient

public PdVector evalGradient(PdVector coord,
                             PdVector gradient)

Evaluate Area gradient of a coord vector using the stiffness matrix of a PnArea instance. Along boundary gradient is modified to fulfill any boundary constraints. Special feature for outside calls: If outside wants to evaluate the gradient without allocating gradient, then instead of gradient a null may be passed. In this case the gradient information is store in an internal variable which is returned as gradient. Handle with care and do not modify size returned gradient.

If no special boundary constraints are set, then you may use setZeroGradientAtBounds(boolean) to set the gradient zero at the boundary (or free again).

Overrides:

evalGradient in class PnFunction

Parameters:

coord - Coordinate vector with list of doubles

gradient - Gradient vector to be modified, maybe null.

See Also:

vgp.discrete.harmonic.PnAreaEnergy

evalHessian

public abstract PdMatrix evalHessian(PdMatrix hessian)

Subclass must supply method to compute hessian of energy.

Overrides:

evalHessian in class PnFunction

Parameters:

hessian - Hessian of energy with square size

getSpectrum

public PdVector[] getSpectrum(PdVector eValue,
                              PdVector[] eVector)

Compute eigenvalues and eigenvectors of normalized hessian.

Parameters:

eValue - Vector to store the eigenvalues. Size will be adjusted.

eVector - Possibly empty array to store the eigenvectors. Will be returned.

testEigenvalues

public void testEigenvalues()