Lagrange interpolation

/* Write C program to implement the Lagrange interpolation.*/

#include<stdio.h>
#include<conio.h>
#define MaxN 90

void main()
{
 float arr_x[MaxN+1], arr_y[MaxN+1], numerator, denominator, x, y=0;
 int i, j, n;
 clrscr();
 printf("Enter the value of n: \n");
 scanf("%d", &n);
 printf("Enter the values of x and y: \n");
 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);
 for (i=0; i<=n; i++)
 {
  numerator=1;
  denominator=1;
  for (j=0; j<=n; j++)
  if(j!=i)
  {
   numerator *= x-arr_x[j];
   denominator *= arr_x[i]-arr_x[j];
  }
  y+=(numerator/denominator)*arr_y[i];
 }
printf("When x=%4.1f y=%7.1f\n",x,y);
getch();
}

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