Converting jagged array to 2D array C#

Question

I\'m trying to convert this function from Jagged Array to 2D array, and I\'m not able to convert everything Original Function:

public static double[][] Inver         


        

Answer 1

NOTE: your jagged array should be orthogonal, hence sub arrays lengths should all be equal, otherwise you cannot convert it to a 2D array.

the part:

double[,] x = new double[n][];
for (int i = 0; i < n; i++)
{
    //how to convert this line?
    x[i] = new double[A[i].Length];
}

is just for initializing a new jagged array which can easily replaced with

double[,] x = new double[A.GetLength(0),A.GetLength(1)];

and in

   //This one too?!
    e = new double[A[i].Length];

you are essentially creating an array with same length of sub array i in A so we can replace it with

    e = new double[A.GetLength(1)]; //NOTE: second dimension

as mentioned before, All sub arrays length are equal so we can use second dimension length instead.

and the whole method would be:

    public static double[,] InvertMatrix2D(double[,] A)
    {
        int n = A.Length;
        //e will represent each column in the identity matrix
        double[] e;
        //x will hold the inverse matrix to be returned
        double[,] x = new double[A.GetLength(0),A.GetLength(1)];

        /*
        * solve will contain the vector solution for the LUP decomposition as we solve
        * for each vector of x.  We will combine the solutions into the double[][] array x.
        * */
        double[] solve;

        //Get the LU matrix and P matrix (as an array)
        Tuple results = LUPDecomposition(A);

        double[,] LU = results.Item1;
        int[] P = results.Item2;

        /*
        * Solve AX = e for each column ei of the identity matrix using LUP decomposition
        * */
        for (int i = 0; i < n; i++)
        {
            e = new double[A.GetLength(1)]; //NOTE: second dimension
            e[i] = 1;
            solve = LUPSolve(LU, P, e);
            for (int j = 0; j < solve.Length; j++)
            {
                x[j,i] = solve[j];
            }
        }
        return x;
    }