EliminasiGauss

import java.util.Scanner;

   public class EliminasiGauss {

      public static void main(String[] args) {

     Scanner in = new Scanner(System.in);

     double[][] A;              // The coefficients
     double[]   b;              // The RHS
     double     pivot, factor;
     int        n;              // Number of variables

     int i, j, k;

     System.out.print("Number of unknows : ");
     n = in.nextInt();          // Read in problem size

     A = new double[n][n];      // Reserve space for coefficient matrix
     b = new double[n];         // Reserve space for RHS vector

     /* -----------------------------------
        Read in the rows, one row at a time
        ----------------------------------- */

     for (i = 0; i < n; i++) {
        // Read in row i's coefficients
        for (j = 0; j < n; j++)
        {
        System.out.print("A["+i+"]["+j+"] = ");
        A[i][j] = in.nextDouble();
        }

        // Read in row i's RHS
        System.out.print("B["+i+"] \t= ");
        b[i] = in.nextDouble();
            System.out.println();
     }

     /* -------------------------------
        The Gaussian elimination method
        ------------------------------- */

     for (i = 0; i < n; i++) {
            // Process row i

        /* ----------------
           (A) Select pivot
           ---------------- */
        pivot = A[i][i];

        /* -------------------
           (B) Normalize row i
           ------------------- */
        for (j = 0; j < n; j++)
           A[i][j] = A[i][j] / pivot;

        b[i] = b[i] / pivot;

        /* ---------------------
           (C) Sweep using row i
           --------------------- */
        for (k = 0; k < n; k++) {

           if ( k != i ) {

          factor = A[k][i];

          for (j = 0; j < n; j++)
             A[k][j] = A[k][j] - factor*A[i][j];

          b[k] = b[k] - factor*b[i];
           }
        }
     }

     System.out.println("Solution : ");

     for (i = 0; i < n; i++)
        System.out.println("x" + (i+1) + " = " + b[i]);
         /* -------------------------------------
        Soal dari ppt :
            27 x1 +  6 x2 -    x3 = 85  .....(1a)
             6 x1 + 15 x2 +  2 x3 = 72  .....(1b)
               x1 +    x2 + 54 x3 = 110 .....(1c)
        ------------------------------------- */
      }
   }