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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