Matriz diagonal

  static void diagonal (int a [] [], int n, int m)

    {     int i, j;

        for (i = 1 ; i <= m ; i++)

        {

            for (j = 1 ; j <= n ; j++)

            {

                if (i == j)

                    System.out.print (a [i] [j] + " ");

                else

                    System.out.print (0 + " ");

            }

            System.out.println ();

        }

    }