Algoritmi6.1 - Gauss

package Kapitulli6;

/**
 * @author Kushtrim
 * @version 1.01
 */
public class Gaus
{
    public static void main (String[] args)
    {
        double A[][] = {{0},
                {0, 1,-1,2,-1,-8},
                {0, 2,-2,3,-3,-20},
                {0,1,1,1,0,-2},
                {0,1,-1,4,3,4}};

        //   A = nderroVendet(A,2,3);

        // gaussi
        int n = 4;
        for ( int i = 1 ; i<=n-1;i++)
        {

            if (A[i][i] ==0 )
            {
                int  p=-1;
                label:
                for ( int k = i ; k<=n ; k++)
                {
                    if ( A[k][i] != 0)
                    {
                        p=k;
                        break label;
                    }
                }

                if( p == -1)
                {
                    System.out.println("No unique solution exists 1");
                    System.exit(0);
                }
                else
                {

                    System.out.println("Nderrojne vendet " + p + " me " +i);
                    A  = nderroVendet(A,p,i);
                }
            }

            double[][] m = new double[A.length][A[1].length];
            for(int j = i+1 ; j<=n ; j++)
            {
                m[j][i]=A[j][i]/A[i][i];                //step 6
                for ( int r = i ; r <= n+1;r++)
                {
                    A[j][r]=A[j][r] - m[j][i]*A[i][r];
                }

            }

        }

        for ( int i=1; i<= 4;  i++)
        {
            for ( int j = 1 ; j<=5; j++)
            {
                System.out.print(A[i][j] + "\t");
            }

            System.out.println();
        }
        //step7
        if (A[n][n] ==0)
        {
            System.out.println("No unique solution exists 2");
            System.exit(0);
        }

        //step8
        double[] x = new double[n+1];
        x[n] = A[n][n+1]/A[n][n];

        for ( int q = n-1 ; q>=1;q--)
        {
            double aa = A[q][n+1];
            for ( int j=q+1; j<=n ; j++)
            {
                aa = aa - A[q][j]*x[j];
            }
            x[q] = aa/A[q][q];

        }

        for ( int w = 0 ; w <n ; w++)
        {
            System.out.println("x" + (w+1) + " = " + x[w+1]);
        }

    }

    public static double[][] nderroVendet( double [][] A , int p, int i)
    {
        for ( int j =0; j<A[1].length; j++)
        {
            double temp = A[p][j];
            A[p][j] = A[i][j];
            A[i][j] = temp;
        }
        return A;
    }
}