jacobi

#include<stdio.h>
#include<conio.h>
#include<math.h>
#define error 0.0001
void main()
{
    double a[50][50],b[50],y[50],z[50],s=0,sum;
    int f,k=1,n,i,j,key=0;
    printf("enter the number of equations to enter\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]);
            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);
    for(i=0;i<n;i++)
        y[i]=(b[i]/a[i][i]);
    do
    {
        k=1;
        key=0;
        for(i=0;i<n;i++)
        {
            sum=b[i];
            for(j=0;j<n;j++)
            {
                if(j==i)
                    break;
                sum=sum-(a[i][j]*y[j]);
            }
            z[i]=(sum/a[i][i]);
            if(fabs((z[i]-y[i])/z[i])>error)
                key=1;
        }
        if(key==1)
        {
            for(i=0;i<n;i++)
                y[i]=z[i];
            k=0;

        }
    }while(k==0);
    printf("the values of the unknowns are:\n");
    for(i=0;i<n;i++)
        printf("x %d  %.4lf\n",i+1,z[i]);
}

OUTPUT:
enter the number of equations to enter
3
enter the coefficients of equation:1
2 1 1 5
enter the coefficients of equation:2
3 5 2 15
enter the coefficients of equation:3
2 1 4 8
the values of the unknowns are:
x 1  2.5000
x 2  1.5000
x 3  0.3750
Press any key to continue