用递归方法求N阶勒让德多项式的值

/*用递归方法求N阶勒让德多项式的值*/
#include<iostream>
using namespace std;
double lrd(int n ,double x){
	
	if(n<0)cout<<"error"; 
	else if(n==0){
		x=1;
		return x; 
	}
	else if(n==1){
		return x;
		} else if(n>1){
			x=((2*n-1)*x-lrd(n-1,x)-(n-1)*lrd(n-2,x))/n;
			return x;
		}
} 
int main(){
	int n;
	double x,r;
	cout<<"please input x=";
	cin>>x;
	cout<<endl;
	cout<<"please input n=";
	cin>>n;
	cout<<endl;
	cout<<"result:"<<lrd(n,x)<<endl;
	return 1; 
}