Program to implement stirling formula

#include<stdio.h>

#include<conio.h>

#include<math.h>

#include<process.h>

void main()

{

      int n;

      int i,j;

      float ax[10];

      float ay[10];

      float h;

      float p;

      float diff[20][20];

      float x,y;

      float y1,y2,y3,y4;

      clrscr();

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

      scanf("%d",&n);

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

      for(i=0;i<n;i++)

      {

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

      scanf("%f",&ax[i]);

      }

      printf( "\n enter the values for y \n");

      for(i=0;i<n;i++)

      {

      printf("\n enter the value for 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",&ax);

      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;

      y1=p*(diff[i][1]+diff[i-1][1])/2;

      y2=p*p*diff[i-1][2]/2;

      y3=p*(p*p-1)*(diff[i-1][3]+diff[i-2][3])/6;

      y4=p*p*(p*p-1)*diff[i-2][4]/24;

      y=ay[i]+y1+y2+y3+y4;

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

      getch();

      }