org.biojava.nbio.structure.geometry

Class MomentsOfInertia

java.lang.Object

org.biojava.nbio.structure.geometry.MomentsOfInertia

public class MomentsOfInertia
extends Object

The moment of inertia, otherwise known as the angular mass or rotational inertia, of a rigid body determines the torque needed for a desired angular acceleration about a rotational axis. It depends on the body's mass distribution and the axis chosen, with larger moments requiring more torque to change the body's rotation.

More in https://en.wikipedia.org/wiki/Moment_of_inertia.

Author:

Peter Rose, Aleix Lafita

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	MomentsOfInertia.SymmetryClass

Constructor Summary

Constructors

Constructor and Description
MomentsOfInertia() Creates a new empty instance of MomentsOfInertia

Method Summary

Modifier and Type	Method and Description
void	addPoint(javax.vecmath.Point3d point, double mass)
double	getAsymmetryParameter(double threshold)
javax.vecmath.Point3d	getCenterOfMass()
double[]	getElipsisRadii() The effective value of this distance for a certain body is known as its radius of / gyration with respect to the given axis.
double[][]	getInertiaTensor()
javax.vecmath.Matrix3d	getOrientationMatrix() The orientation Matrix is a 3x3 Matrix with a column for each principal axis.
javax.vecmath.Vector3d[]	getPrincipalAxes() The principal axes of intertia
double[]	getPrincipalMomentsOfInertia()
double	getRadiusOfGyration()
MomentsOfInertia.SymmetryClass	getSymmetryClass(double threshold)
double	symmetryCoefficient()

Methods inherited from class java.lang.Object

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

Constructor Detail

MomentsOfInertia

public MomentsOfInertia()

Creates a new empty instance of MomentsOfInertia

Method Detail

addPoint

public void addPoint(javax.vecmath.Point3d point,
                     double mass)

getCenterOfMass

public javax.vecmath.Point3d getCenterOfMass()

getPrincipalMomentsOfInertia

public double[] getPrincipalMomentsOfInertia()

getPrincipalAxes

public javax.vecmath.Vector3d[] getPrincipalAxes()

The principal axes of intertia

Returns:

getOrientationMatrix

public javax.vecmath.Matrix3d getOrientationMatrix()

The orientation Matrix is a 3x3 Matrix with a column for each principal axis. It represents the orientation (rotation) of the principal axes with respect to the axes of the coordinate system (unit vectors [1,0,0], [0,1,0] and [0,0,1]).

The orientation matrix indicates the rotation to bring the coordinate axes to the principal axes, in this direction.

Returns:

the orientation Matrix as a Matrix3d object

getElipsisRadii

public double[] getElipsisRadii()

The effective value of this distance for a certain body is known as its radius of / gyration with respect to the given axis. The radius of gyration corresponding to Ijj / is defined as / http://www.eng.auburn.edu/~marghitu/MECH2110/C_4.pdf / radius of gyration k(j) = sqrt(I(j)/m)

getRadiusOfGyration

public double getRadiusOfGyration()

getSymmetryClass

public MomentsOfInertia.SymmetryClass getSymmetryClass(double threshold)

symmetryCoefficient

public double symmetryCoefficient()

getAsymmetryParameter

public double getAsymmetryParameter(double threshold)

getInertiaTensor

public double[][] getInertiaTensor()