//Aitken's formula
#include<stdio.h>
#include<conio.h>
void main()
{
int n,m,i,j;
float x,y,q1,q2,a[10][10];
char c;
NEWAIT:
printf("enter the value of n:");
scanf("%d",&n);
m=n;
printf("enter the values of x:");
for(i=0;i<n;i++){
 scanf("%f",&a[i][0]);
 }
printf("enter the values of y:");
for(i=0;i<n;i++){
 scanf("%f",&a[i][1]);
 }
AIT:printf("enter the value of x for which to calculate y:");
scanf("%f",&x);
/*calculation of y */
y=0;
 for(j=1;j<n;j++){
  for(i=0;i<(n-j);i++){
	q1=a[0][j]*(a[j+i][0]-x);
	q2=a[i+1][j]*(a[j-1][0]-x);
	a[i][j+1]=(q1-q2)/(a[i+j][0]-a[j-1][0]);
	y=a[i][j+1];
  }
 }
  printf("\nDifference Table:\n");
 /*printing of table*/
for(j=0;j<n;j++){
 for(i=0;i<m+1;i++){
  printf("%.5f    ",a[j][i]);
  }
 m=m-1;
 printf("\n");
 }
 printf("\ny=%.5f\n",y);
 printf("\nTo give different value of x for same data, press 1");
 printf("\nTo give different set of data press 2");
 printf("\nTo exit press 0\n");
 c=getch();
 if(c=='1')
  goto AIT;
 if(c=='2')
  goto NEWAIT;
}