Package org.biojava.nbio.structure.geometry

Class 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

    • Constructor Detail

      • MomentsOfInertia

        public MomentsOfInertia()
        Creates a new empty instance of MomentsOfInertia

    • Method Detail

      • addPoint

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

      • 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)