C++怎样输出一个小数点后有10位的小数？

#include <iostream>
#include <iomanip>
using namespace std;
//牛顿法
int main() {
	cout << "**************************" << endl;
	cout << "这是第十六题 " << endl;
	cout << "**************************" << endl;
	cout << "请输入初值:";
	double X[100];
	double f1 = 0,f2=0;
	cin >> X[0];
	int i = 0;
	cout << "  k          Xk             Xk+1       " << endl;
	do {
		f1 = X[i] * X[i] * X[i] + 2 * X[i] * X[i] + 10 * X[i] - 20;
		f2 = 3 * X[i] * X[i] + 4 * X[i] + 10;
		X[i + 1] = X[i] - f1 / f2;
		cout << "    " << i << "       " <<fixed<<setprecision(10)<< X[i] << "         " <<fixed<<setprecision(10)<< X[i + 1] << endl;
		i++;
	} while (X[i] - X[i - 1] > 0.000000001 || X[i - 1] - X[i] > 0.000000001);
	cout << endl;
	cout << "小王最棒！！！" << endl;
	return 0;
}