Method det

JSAT/src/jsat/linear/LUPDecomposition.java:58–86

@return the determinant of the original Matrix A, |A|

()

     * @return the determinant of the original Matrix A, |A|
     */
    public double det()
    {
        if(!isSquare())
            throw new ArithmeticException("Rectangual matricies do not have a determinat");
        double det = 1;
        
        for(int i = 0; i < Math.min(U.rows(), U.cols()); i++)
            det *= U.get(i, i);
        
        //We need to swap back P to get the sign, so we make a clone. This could be cached if we need to 
        int rowSwaps = 0;
        
        Matrix pCopy = P.clone();
        //The number of row swaps in P is the sign change
        for(int i = 0; i < pCopy.cols(); i++)
            if(pCopy.get(i, i) != 1)
            {
                rowSwaps++;
                //find the row that has our '1'! 
                int j = i+1;
                while(pCopy.get(j, i) == 0)
                    j++;
                
                pCopy.swapRows(i, j);//Dont really care who we swap with, it will work out in the end
            }
        
        
        return rowSwaps % 2 !=0 ? -det : det;
    }
    
    public Vec solve(Vec b)
    {