СЛАУ метод простых итераций - C (СИ)

#include "stdafx.h"
#include <stdio.h>
#include <conio.h>
#include <math.h>
 
int _tmain(int argc, _TCHAR* argv[])
{
    float m[3][3]={8,-6,1,3,9,-5,1,2,-7}, a[3]={16,7,-21},
    x[3], E[3][1], x0[3];
  long det;
  int i,j;
  float e=0.0001, n[3][3],d[3];
  printf("\nThe matrix is:\n");
  for(i=0;i<3;i++)
    {
      printf("\n");
       for(j=0;j<3;j++)
         printf("%.1f\t", m[i][j]);
    }
  printf("\n\nFree vector is:\n");
  for(i=0;i<3;i++)
    {
      printf("\n");
         printf("%.1f\t", a[i]);
    }
  det=(m[0][0]*m[1][1]*m[2][2]+m[0][1]*m[1][2]*m[2][0]+m[1][0]*m[2][1]*
  m[0][2])-(m[2][0]*m[1][1]*m[0][2]+m[0][0]*m[2][1]*m[1][2]+
  m[1][0]*m[0][1]*m[2][2]);
    if (det!=0)
      printf("\n\nDeterminant is %ld, the system has the single solution;", det);
    else printf("The system hasn't the single solution;");
  if ((fabs(m[0][0])>m[0][1]+m[0][2])&&(fabs(m[1][1])>m[1][0]+m[1][2])&&(fabs(m[2][2])>
   m[2][0]+m[2][1]))
     printf("\n\nMethod is converging;");
  else printf("\n\nMethod is not converging;");
   for(i=0;i<3;i++)
       for(j=0;j<3;j++)
          {
            if (i==j) n[i][j]=0;
            else n[i][j]=m[i][j]/m[i][i];
            d[i]=a[i]/m[i][i];
          }
       printf("\n\nThe matrix for iterations is:\n");
       for(i=0;i<3;i++)
          {
             printf("\n");
              for(j=0;j<3;j++)
                printf("%.2f\t", n[i][j]);
           }
       printf("\n\nNew vector:\n");
    for(i=0;i<3;i++)
          {
             printf("\n");
                printf("%.2f", d[i]);
           }
for(i=0;i<3;i++) x0[i]=d[i];
  do
     {
      for(i=0;i<3;i++)
        x[i]=0;
          for(j=0;j<3;j++)
          {
              x[i]=x[i]+n[i][j]*x0[i];
          }
        x[i]=x[i]+d[i];
        E[i][j]=fabs(x[i]-x0[i]);
          for(i=0;i<3;i++)
              if (e<E[i][j])
                  e=E[i][j];
          
          printf("\n\npogreshnost'=%.2f",E[i][j]);
      }
        while(e>=0.0001);
    printf("\n\nResult:\n");
    for(i=0;i<3;i++)    
        printf("\n%.1f",x[i]);
      getch();
        return 0;
   }