Example usage for org.apache.commons.math3.linear RealVector mapAddToSelf

Introduction

In this page you can find the example usage for org.apache.commons.math3.linear RealVector mapAddToSelf.

Prototype

public RealVector mapAddToSelf(double d) 

Source Link

Document

Add a value to each entry.

Usage

From source file:ellipsoidFit.FitPoints.java

/**
 * Solve the polynomial expression Ax^2 + By^2 + Cz^2 + 2Dxy + 2Exz + 2Fyz +
 * 2Gx + 2Hy + 2Iz from the provided points.
 * /*  w  ww.  j  a  va2s  .  com*/
 * @param points
 *            the points that will be fit to the polynomial expression.
 * @return the solution vector to the polynomial expression.
 */
private RealVector solveSystem(ArrayList<ThreeSpacePoint> points) {
    // determine the number of points
    int numPoints = points.size();

    // the design matrix
    // size: numPoints x 9
    RealMatrix d = new Array2DRowRealMatrix(numPoints, 9);

    // Fit the ellipsoid in the form of
    // Ax^2 + By^2 + Cz^2 + 2Dxy + 2Exz + 2Fyz + 2Gx + 2Hy + 2Iz
    for (int i = 0; i < d.getRowDimension(); i++) {
        double xx = Math.pow(points.get(i).x, 2);
        double yy = Math.pow(points.get(i).y, 2);
        double zz = Math.pow(points.get(i).z, 2);
        double xy = 2 * (points.get(i).x * points.get(i).y);
        double xz = 2 * (points.get(i).x * points.get(i).z);
        double yz = 2 * (points.get(i).y * points.get(i).z);
        double x = 2 * points.get(i).x;
        double y = 2 * points.get(i).y;
        double z = 2 * points.get(i).z;

        d.setEntry(i, 0, xx);
        d.setEntry(i, 1, yy);
        d.setEntry(i, 2, zz);
        d.setEntry(i, 3, xy);
        d.setEntry(i, 4, xz);
        d.setEntry(i, 5, yz);
        d.setEntry(i, 6, x);
        d.setEntry(i, 7, y);
        d.setEntry(i, 8, z);
    }

    // solve the normal system of equations
    // v = (( d' * d )^-1) * ( d' * ones.mapAddToSelf(1));

    // Multiply: d' * d
    RealMatrix dtd = d.transpose().multiply(d);

    // Create a vector of ones.
    RealVector ones = new ArrayRealVector(numPoints);
    ones.mapAddToSelf(1);

    // Multiply: d' * ones.mapAddToSelf(1)
    RealVector dtOnes = d.transpose().operate(ones);

    // Find ( d' * d )^-1
    DecompositionSolver solver = new SingularValueDecomposition(dtd).getSolver();
    RealMatrix dtdi = solver.getInverse();

    // v = (( d' * d )^-1) * ( d' * ones.mapAddToSelf(1));
    RealVector v = dtdi.operate(dtOnes);

    return v;
}

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