everett formula

#include<stdio.h>

#include<conio.h>

#include<math.h>

#include<process.h>

#include<string.h>

void main()

      {

            int n;

            int i,j;

            float ax[10];

            float ay[10];

            float x;

            float nr,dr;

            float y=0;

            float h;

            float p,q;

            float diff[20][20];

            float y1,y2,y3,y4;

            float py1,py2,py3,py4;

            clrscr();

            printf("\n enter the number of terms -");

            scanf("%d",&n);

            printf("\n\n enter the value in the terms of x -");

            for(i=0;i<n;i++)

            {

                  printf("\n\n enter the value of x%d -",i+1);

                  scanf("%f",&ax[i]);

                  }

            printf("\n\n enter the value in the form of y -");

            for(i=0;i<n;i++)

            {

            printf("\n\n enter the value of y%d -",i+1);

            scanf("%f",&ay[i]);

            }

            printf("\n enter the value of x for ");

            printf("\n which you want the value of y -");

            scanf("%f",&x);

            h=ax[1]-ax[0];

            for(i=0;i<n-1;i++)

            {

            diff[i][1]=ay[i+1]-ay[i];

            }

            for(j=2;j<=4;j++)

            {

            for(i=0;i<n-j;i++)

            {

            diff[i][j]=diff[i+1][j-1]-diff[i][j-1];

            }

            }

            i=0;

            do

            {

            i++;

            }

            while(ax[i]<x);

            i--;

            p=(x-ax[i])/h;

            q=1-p;

            y1=q*(ay[i]);

            y2=q*(q*q-1)*diff[i-1][2]/6;

            y3=q*(q*q-1)*(q*q-4)*(diff[i-2][4])/120;

            py1=p*ay[i+1];

            py2=p*(p*p-1)*diff[i][2]/6;

            py3=p*(p*p-1)*(p*p-4)*(diff[i-1][4])/120;

            y=y1+y2+y3+y4+py1+py2+py3;

            printf("\n when x=%6.2f,y=%6.8f",x,y);

            printf("\n\n press enter to exit ");

            getch();

            }