In this tutorial, we are going to write a program that finds the result for lagranges's interpolation formula.
You don't have write any logic for the program. Just convert the formula into code. Let's see the code.
Example
#include<bits/stdc++.h>
using namespace std;
struct Data {
int x, y;
};
double interpolate(Data function[], int xi, int n) {
double result = 0;
for (int i = 0; i < n; i++) {
double term = function[i].y;
for (int j = 0; j < n; j++) {
if (j != i) {
term = term * (xi - function[j].x) / double(function[i].x - function[j].x);
}
}
result += term;
}
return result;
}
int main() {
Data function[] = {{0,3}, {1,2}, {6,9}, {10,17}};
cout << interpolate(function, 3, 5) << endl;
return 0;
}Output
If you run the above code, then you will get the following result.
3
Conclusion
If you have any queries in the tutorial, mention them in the comment section.