#include<iostream>
using namespace std;
float lrddxs(int n,int x);
void main()
{
int n,x;
float result;
cout<<"请输入勒让德多项式的阶数（正整数）:";
cin>>n;
cout<<"请输入自变量的值（正整数）：";
cin>>x;
result=lrddxs(n,x);
cout<<"所求多项式的值为："<<result;
}
float lrddxs (int n,int x)
{ float s;
if(n==0) s=1;
else if(n==1) s=x;
else
s=((2*n-1)*x*lrddxs(n-1,x)-(n-1)*lrddxs(n-2,x))/n;
return s;
}
