二分法梯形公式求积分

#include <iostream>
#include <iomanip>
#include <math.h>
using namespace std;
//二分梯形积分
//本函数用来求sinx/x在(0,1)区间的积分
long double f(double l) {
	return sin(l) / l;
}
long double Tn(double a, double b, long double xy) {//变步长梯形法
	cout << "        二分次数           积分结果" << endl;
	long double S, T1, T2,m;//m指实际截断误差
	double h,x;//步长
	int k;//二分次数
	T1 = (1 + f(b)) / 2;
	h = b - a;
	k = 0;
	do {
		cout << "          " << k << "                 " << fixed << setprecision(10) << T1 << endl;
		S = 0;
		x = a + h / 2;//第一个要加的数
		while (x < b) {
			S = S + f(x);
			x = x + h;
		}
		T2 = T1 / 2 + S * h / 2;
		m = (T2 - T1)*(T2 - T1);
		h = h / 2;
		T1 = T2;
		k++;
	} while (m >= xy * xy);
	cout << "          " << k << "                 " << fixed << setprecision(10) << T1 << endl;
	return T2;
}

int main() {
	cout << "(〃'▽'〃)***!!!这是一个求函数f(x)积分的区间!!!***φ(>ω<*) " << endl;
	double a, b;
	long double xy,y;
	cout << "请依次输入带积分函数的积分区间" << endl;
	cout << "左区间：";
	cin >> a;
	cout << "右区间：";
	cin >> b;
	cout << "请输入函数结果所允许的最大误差:";
	cin >> xy;
	cout << endl;
	y = Tn(a, b, xy);
	cout << "最后的结果为" << y << endl;
	cout << "******小王最棒！******" << endl;
	return 0;
}

　　调试结果: