TwoByTwoMatrix

public class TwoByTwoMatrix extends SquareMatrix
{
    private static final double[][] IDENTITY_MATRIX = {{1,0}, {0,1}};
    
    /**
     * constructor for the class TwoByTwoMatrix
     */
    public TwoByTwoMatrix()
    {
        super(2);
    }
    
    
    /**
     * will return the inverse of the matrix
     * if the inverse exists
     * @return 
     */
    public double[][] findInverse()
    {
        
       
        if (this.doesInverseExist() == false)
        {
            System.out.println("there is no inverse  for this system of equations(the matrix is singular)");
        }
        if (this.doesInverseExist() == true)
        { 
            double[][] inverseMatrix = new double[2][2];
            inverseMatrix = this.multiplyMatrix((1 / this.determinant()), this.adjoint());   
           return inverseMatrix;
        }
        return null;
    }
    /**
     * returns true if an inverse of the matrix exists
     * returns false if an inverse of the matrix does not exist
     * @return 
     */
    public boolean doesInverseExist()
    {
        if (this.determinant() == 0)
        {
            return false;
        }
            if (!(this.determinant() == 0))
        {
            return true;
        }
            return false;        
    }
    /**
     * returns true if the matrix is orthogonal
     * returns false if the matrix is not orthogonal
     * @param trans
     * @param mat
     * @return 
     */
    public boolean isOrthogonal(double[][] trans, double[][] mat)
    {
        trans = this.matrixTranspose(mat);
      
        if (this.multiplyMatrices(trans, mat) == this.IDENTITY_MATRIX)
            return true;
        if (this.multiplyMatrices(trans, mat)!= this.IDENTITY_MATRIX)
            return false;
        return false;
    }
    /**
     * returns the determinant of the matrix
     * @return 
     */
    public double determinant()
    {
        double determinant;
        determinant = (this.getAMatrixValue(0, 0) * this.getAMatrixValue(1, 1)) - (this.getAMatrixValue(0, 1) * this.getAMatrixValue(1, 0));
        return determinant;
    }
    /**
     * returns the adjoint of the matrix
     * @return 
     */
    public double[][] adjoint()
    {
        double[][] adj = new double[2][2];
        adj[0][0] = this.getAMatrixValue(1, 1);
        adj[0][1] = -(this.getAMatrixValue(0, 1));
        adj[1][0] = -(this.getAMatrixValue(1, 0));
        adj[1][1] = this.getAMatrixValue(0, 0);
        return adj;
    }
    /**
     * multiplies a matrix by a factor
     * overloads multiplyMatrix(double) 
     * in Matrix class
     * @param factor
     * @param mat
     * @return 
     */
    public double[][] multiplyMatrix(double factor, double[][] mat)
    {  
        for(int i = 0; i < 2; i++)
        {
            for (int j =0; j < 2; j++)
                mat[i][j] = (mat[i][j] * factor);
        }
        return mat;
    }
    
    /**
     * multiplies together
     * two TwoByTwo matrices
     * @param mat1
     * @param mat2
     * @return 
     */
    public double[][] multiplyMatrices(double[][] mat1, double[][] mat2)
    {
        double[][] retMat = new double[2][2];
        retMat[0][0] = ((mat1[0][0] * mat2[0][0]) + (mat1[0][1] * mat2[1][0]));
        retMat[0][1] = ((mat1[0][0] * mat2[0][1]) + (mat1[0][1] * mat2[1][1]));
        retMat[1][0] = ((mat1[1][0] * mat2[0][0]) + (mat1[1][1] * mat2[1][0]));
        retMat[1][1] = ((mat1[1][0] * mat2[0][1]) + (mat1[1][1] * mat2[1][1]));   
        return retMat;
    }
    
    
    
            
    
}