/*******************************/
/*  Gauss-Jordan法             */
/*******************************/
#include <iostream>
#include <iomanip>
#include <stdlib.h>
#include <string.h>
#include <math.h> 
using namespace std;
#define N 9    // 9x9 matrix 
int main(int argc, char *argv[] ){
  double a[N][N+1] = 
  {     
    {4,-1,0,-1,0,0,0,0,0,0}, 
    {-1,4,-1,0,-1,0,0,0,0,0}, 
    {0,-1,4,0,0,-1,0,0,0,0.25}, 
    {-1,0,0,4,-1,0,-1,0,0,0}, 
    {0,-1,0,-1,4,-1,0,-1,0,0}, 
    {0,0,-1,0,-1,4,0,0,-1,0.5},
    {0,0,0,-1,0,0,4,-1,0,0.25},
    {0,0,0,0,-1,0,-1,4,-1,0.5},
    {0,0,0,0,0,-1,0,-1,4,1.5}
  };
  double p, d;//ピポッド, 
  int i, j, k;
 for (k=0; k<N; k++)
   {
        p = a[k][k];    // pivot coefficient
        for (j=k; j<N+1; j++)
        { 
            a[k][j]=a[k][j]/p;      /* substract pivot gyou by p *////ピポッドで割る
        }
        for (i=0; i<N; i++)
        {    /* pivot sweep out */
            if (i!=k)
            {
                d = a[i][k];
                for (j=k; j<N+1; j++)
                {
	                a[i][j]=a[i][j]-d*a[k][j];
                }
            }
        } 
     
    }
    for (k=0; k<N; k++)
        {
            cout << "x" << k+1<<"="<<a[k][N]<<endl;
        }
 return 0;
}