gauss seidel

#include<stdio.h>
#include<math.h>
#define e 0.001
void main()
{
    double a[50][50],b[50],x[50];
    double y,d,s=0,sum=0;
    int n,j,i,f;
    printf("enter the number of equation\n");
    scanf("%d",&n);
    do
    {
        f=1;
        for(i=0;i<n;i++)
        {
            printf("enter the coefficients of equation:%d\n",i+1);
            for(j=0;j<n;j++)
                scanf("%lf",&a[i][j]);
            printf("enter the constant of the equation\n");
            scanf("%lf",&b[i]);
        //  for(j=0;j<(n-1);j++)
        //      s=s+a[i][j];
        //  s=s-a[i][i];
        //  if(fabs(a[i][i])<fabs(s))
        //  {
        //      printf("the equation doesnt converge re-enter equations\n");
        //      f=0;
        //      break;
        //  }
        }
    }while(f==0);
    printf("enter the initial values ofx\n");
    for(i=0;i<n;i++)
        scanf("%lf",&x[i]);
    do
    {
        f=1;
        for(i=0;i<n;i++)
        {
            sum=0;
            for(j=0;j<n;j++)
            {
                if(i!=j)
                    sum=sum+(a[i][j]*x[j]);
            }
            y=(b[i]-sum)/a[i][i];
            printf("x%d=%.2lf\n",i+1,y);
            d=fabs(y-x[i]);
            x[i]=y;
            if(d>=e)
                f=0;
        }
    }while(f==0);
    printf("the values of x are:\n");
    for(i=0;i<n;i++)
        printf("x%d: %.4lf\n",i+1,x[i]);
}