Input may contain multiple test cases. The first line is a positive integer N, denoting the number of test cases below. One case One line. The line will consist of a pair of integers a and b, denoting the ellipse equation , A pair of integers l and r, mean the L is (l, 0) and R is (r, 0). (-a <= l <= r <= a).

#include <iostream>
#include <math.h>
using namespace std;

const double esp = 1e-10;
double a,b;

double f(double x)
{
	return b * sqrt(1.0-(x*x)/(a*a));
}

double simpson(double l,double r)
{
	return (f(l)+4*f((l+r)/2.0)+f(r))/6.0*(r-l);
}

double integral(double l,double r)
{
	double mid = (l+r)/2.0;
	double res = simpson(l,r);
	if (fabs(res-simpson(l,mid)-simpson(mid,r)) < esp)
		return res;
	else
		return integral(l,mid) + integral(mid,r);
}
int main()
{
	int T;
	double l,r;
	cin >> T;
	while (T--)
	{
		cin >> a >> b >> l >> r;
		printf("%.3lf\n",2*integral(l,r));
	}
	return 0;
}