Newton- Gregory forward interpolation

/* Write C program to implement the Newton- Gregory forward interpolation.*/

#include<stdio.h>
#include<conio.h>
#define MaxN 100
#define Order_of_diff 4

void main ()
{
 float arr_x[MaxN+1], arr_y[MaxN+1], numerator=1.0, denominator=1.0, x, y, p, h, diff_table[MaxN+1][Order_of_diff+1];
 int i,j,n,k;
 clrscr();

 printf("Enter the value of n \n");
 scanf("%d",&n);
 printf("Enter the values of x and y");

 for(i=0; i<=n; i++)
 scanf("%f%f", &arr_x[i], &arr_y[i]);
 printf("Enter the value of x at which value of y is to be calculated");
 scanf("%f", &x);
 h=arr_x[1]-arr_x[0];

 for(i=0; i<=n-1; i++)
 diff_table[i][1]=arr_y[i+1]-arr_y[i];/*Creating the difference table and calculating first order differences*/
 for(j=2; j<=Order_of_diff; j++)/*Calculating higher order differences*/
 for(i=0; i<=n-j; i++)
 diff_table[i][j]=diff_table[i+1][j-1] - diff_table[i][j-1];
 i=0;

 while(!(arr_x[i]>x)) /* Finding x0 */
 i++;
 i--;
 p=(x-arr_x[i])/h;
 y=arr_y[i];

 for (k=1; k<=Order_of_diff; k++)
 {
  numerator *=p-k+1;
  denominator *=k;
  y +=(numerator/denominator)*diff_table[i][k];
 }
printf("When x=%6.1f, y=%6.2f\n",x, y);
getch();
}

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