拉格朗日插值

#include <iostream>
using namespace std;

double lagrange(double x);
double baseFunc(double x,double xi[], int i, int times);
double polynominal(double x, double xi[], int times);
double yFunc(double x);

int main(int argc, const char * argv[]) {
    cout<<"请输入插值次数"<<endl;
    int t;
    cin>>t;
    double xi[t];
    for (int j = 0; j <= t; ++j) {
        cout<<"请每次输入一个插值节点xi"<<endl;
        cin>>xi[j];
    }
    double x;
    cout<<"请输入要插值估计的x"<<endl;
    cin>>x;
    double result = polynominal(x, xi, t);
    cout<<result<<endl;
    
    return 0;
}

double polynominal(double x, double xi[], int times){
    double poly = 0;
    for (int j = 0; j <= times; ++j) {
        poly += (baseFunc(x, xi, j, times) * yFunc(xi[j]));
    }
    return poly;
}

double baseFunc(double x,double xi[], int i, int times){
    double l;
    double denominator = 1;
    double numerator = 1;
    for (int j = 0; j <= times; ++j) {
        if(j != i){
            denominator *= (xi[i] - xi[j]);
            numerator *= (x - xi[j]);
        }
    }
    l = numerator / denominator;
    return l;
}

double yFunc(double x){
    double re = sqrt(x);
    return re;
}