public class Matrix2x2 private double matrix new double public double

public class Matrix2x2 {
    private double[][]matrix = new double[2][2];

    public double[][] getMatrix() {
        return matrix;
    }

    public void setMatrix(double[][] matrix) {
        this.matrix = matrix;
    }

    public Matrix2x2() {
        this(new double[][]{{0,0},{0,0}});
    }
    public Matrix2x2(double c) {
        this(new double[][]{{c,c},{c,c}});
    }
    public Matrix2x2(double[][] matrix) {
        this.matrix = matrix;
    }
    public Matrix2x2(double b1, double b2, double b3, double b4) {
        this(new double[][]{{b1,b2},{b3,b4}});
    }
    public Matrix2x2 add(Matrix2x2 matr) {
        Matrix2x2 result = new Matrix2x2();
        for (int i = 0; i < 2; i++) {
            for (int j = 0; j < 2; j++) {
                result.matrix[i][j] = this.matrix[i][j] + matr.matrix[i][j];
            }
        }
        return result;
    }
    public void add2(Matrix2x2 matr) {
        for (int i = 0; i < 2; i++) {
            for (int j = 0; j < 2; j++) {
                this.matrix[i][j] += matr.matrix[i][j];
            }
        }
    }
    public Matrix2x2 sub(Matrix2x2 matr) {
        Matrix2x2 result = new Matrix2x2();
        for (int i = 0; i < 2; i++) {
            for (int j = 0; j < 2; j++) {
                result.matrix[i][j] = this.matrix[i][j] - matr.matrix[i][j];
            }
        }
        return result;
    }
    public void sub2(Matrix2x2 matr) {
        for (int i = 0; i < 2; i++) {
            for (int j = 0; j < 2; j++) {
                this.matrix[i][j] -= matr.matrix[i][j];
            }
        }
    }
    public Matrix2x2 multNumber(double v) {
        Matrix2x2 result = new Matrix2x2();
        for (int i = 0; i < 2; i++) {
            for (int j = 0; j < 2; j++) {
                result.matrix[i][j] = this.matrix[i][j] * v;
            }
        }
        return result;
    }
    public void multNumber2(double v) {
        for (int i = 0; i < 2; i++) {
            for (int j = 0; j < 2; j++) {
                this.matrix[i][j] *= v;
            }
        }
    }
    public Matrix2x2 mult(Matrix2x2 matr) {
        Matrix2x2 result = new Matrix2x2();
        for (int i = 0; i < 2; i++) {
            for (int j = 0; j < 2; j++) {
                for (int k = 0; k < 2; k++) {
                    result.matrix[i][j] += this.matrix[i][k] * matr.matrix[k][j];
                }
            }
        }
        return result;
    }
    public void mult2(Matrix2x2 matr) {
        Matrix2x2 result = new Matrix2x2();
        for (int i = 0; i < 2; i++) {
            for (int j = 0; j < 2; j++) {
                for (int k = 0; k < 2; k++) {
                    result.matrix[i][j] += this.matrix[i][k] * matr.matrix[k][j];
                }
            }
        }
        this.matrix = result.matrix;
    }
    public double det() {
        return matrix[1][1] * matrix[2][2] - matrix[1][2] * matrix[2][1];
    }
}