package math3d;
public class Eigensystem2x2Double { double[][] m; double[] eigenVectors; double[] eigenValues;
public Eigensystem2x2Double(double[][] symmetricMatrix) { this.m = symmetricMatrix; if (this.m[0][1] != this.m[1][0]) { throw new RuntimeException("Eigensystem2x2Double only works with symmetric matrices"); } }
public void getEvalues(double[] eigenValues) { eigenValues[0] = this.eigenValues[0]; eigenValues[1] = this.eigenValues[1]; }
public double[] getEvaluesCopy() { return (double[])this.eigenValues.clone(); }
public double[] getEvalues() { return this.eigenValues; }
public boolean findEvalues() { this.eigenValues = new double[2]; double A = this.m[0][0]; double B = this.m[0][1]; double C = this.m[1][1]; double a = 1.0; double b = -(A + C); double c = A * C - B * B; double discriminant = b * b - 4.0 * a * c; if (discriminant < 0.0) { return false; } else { this.eigenValues[0] = (-b + Math.sqrt(discriminant)) / (2.0 * a); this.eigenValues[1] = (-b - Math.sqrt(discriminant)) / (2.0 * a); return true; } }}
