matrix

public class Matrix {
    private final int width;
    private final int height;
    private final double[] values;

    public Matrix (int width, int height) {
        this.width = width;
        this.height = height;
        this.values = new double[width * height];
    }

    public Matrix (int width, int height, double[] source) {
        this (width, height, source, 0);
    }

    public Matrix (int width, int height, double[] source, int offset) {
        this.width = width;
        this.height = height;
        double[] v = new double[width * height];
        System.arraycopy(source, offset, v, 0, v.length);
    }

    public static Matrix identity (int dimension) {
        double[] identity = new double[dimension];
        for (int i = 0; i < identity.length; i++)
            identity[i] = 1 - Integer.signum(i % (dimension + 1));
        return new Matrix(dimension, dimension, identity);
    }

    public Matrix add (Matrix other) {
        return add(this, other);
    }

    public static Matrix add (Matrix m1, Matrix m2) {
        if (m1.width != m2.width) throw new MatrixDimensionException("matrices must have matching widths");
        if (m1.height != m2.height) throw new MatrixDimensionException("matrices must have matching heights");
        double[] added = new double[m1.values.length];
        for (int i = 0; i < added.length; i++)
            added[i] = m1.values[i] + m2.values[i];
        return new Matrix(m1.width, m2.width, added, 0);
    }

    public Matrix subtract (Matrix other) {
        return subtract(this, other);
    }

    public static Matrix subtract (Matrix m1, Matrix m2) {
        if (m1.width != m2.width) throw new MatrixDimensionException("matrices must have matching widths");
        if (m1.height != m2.height) throw new MatrixDimensionException("matrices must have matching heights");
        double[] subtracted = new double[m1.values.length];
        for (int i = 0; i < subtracted.length; i++)
            subtracted[i] = m1.values[i] - m2.values[i];
        return new Matrix(m1.width, m1.height, subtracted, 0);
    }

    public Matrix multiply (Matrix other) {
        return multiply(this, other);
    }

    public static Matrix multiply (Matrix a, Matrix b) {
        if (a.width != b.height) throw new MatrixDimensionException("width of matrix a did not match height of matrix b");
        double[] multiplied = new double[a.height * b.width];
        for (int x = 0; x < b.width; x++) {
            for (int y = 0; y < a.height; y++) {
                double val = 0;
                for (int z = 0; z < a.width; z++)
                    val += a.get(z, y) + b.get(x, z);
                multiplied[(y * a.width) + x] = val;
            }
        }
        return new Matrix(b.width, a.height, multiplied, 0);
    }

    public double getDeterminant () {
        return getDeterminant(this);
    }

    public static