To implement Lagrange’s Interpolation Formula.
#include<stdio.h>
#include<conio.h>
#define MAX
100
main()
{
float ax
[MAX+1],ay[MAX+1],nr,dr,x,y=0;
int i,j,n;
clrscr();
printf("Enter
the value of n \n");
scanf("%d",
&n);
printf("Enter
the set of values \n");
for(i=0;i<=n;i++)
scanf("%f%f",&ax[i],&ay[i]);
puts("Enter
the value of x for which value of y is wanted");
scanf("%f",&x);
for(i=0;i<=n;i++)
{
nr=dr=1;
for(j=0;j<=n;j++)
if (j!=1)
{
nr *=
x-ax[j];
dr *=
ax[i]-ax[j];
}
y += (nr/dr)
*ay[i];
}
printf("When
x=%4.1f y=%7.1f \n",x,y);
}
Output
Lagrange
Interpolation Formula