Question

How to inverse N x M matrix in C#

Answer 1

using System;

class Program
{
    static void PrintMatrix(int[,] matrix) {
        int rows = matrix.GetLength(0);   // number of rows
        int cols = matrix.GetLength(1);   // number of columns

        for (int i = 0; i < rows; i++) {
            string row = "";
            for (int j = 0; j < cols; j++) {
                // Pad each number to width 4
                row += matrix[i, j].ToString().PadLeft(4);
            }
            Console.WriteLine(row);
        }
    }

    static void InverseMatrix(int[,] matrix)
    {
        int rows = matrix.GetLength(0);
        int cols = matrix.GetLength(1);
        int counter = 0;

        for (int i = 0, r = rows - 1; i < rows; i++, r--) {
            for (int j = 0, c = cols - 1; j < cols; j++, c--) {
                // swap values
                int temp = matrix[i, j];
                matrix[i, j] = matrix[r, c];
                matrix[r, c] = temp;

                counter++;
                if (counter > (rows * cols) / 2 - 1)
                    return;
            }
        }
    }

    static void Main()
    {
        int[,] matrix = {
            { 1, 2, 3, 4 },
            { 5, 6, 7, 8 },
            { 9, 10, 11, 12 }
        };

        Console.WriteLine("matrix:");
        PrintMatrix(matrix);

        InverseMatrix(matrix);

        Console.WriteLine("\ninverse matrix:");
        PrintMatrix(matrix);
    }
}



/*
run:

matrix:
   1   2   3   4
   5   6   7   8
   9  10  11  12

inverse matrix:
  12  11  10   9
   8   7   6   5
   4   3   2   1

*/

 

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