Ellipse

Time Limit: 1000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)

Total Submission(s): 1868    Accepted Submission(s): 792

Problem Description

Math is important!! Many students failed in 2+2’s mathematical test, so let's AC this problem to mourn for our lost youth..

Look this sample picture:

A ellipses in the plane and center in point O. the L,R lines will be vertical through the X-axis. The problem is calculating the blue intersection area. But calculating the intersection area is dull, so I have turn to you, a talent of programmer. Your task is tell me the result of calculations.(defined PI=3.14159265 , The area of an ellipse A=PI*a*b )

Input

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).

 

Output

For each case, output one line containing a float, the area of the intersection, accurate to three decimals after the decimal point.

Sample Input

2 2 1 -2 2 2 1 0 2

 

Sample Output

6.283 3.142

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可以计算椭圆面积了哈哈

注意eps小一点

#include 
       
        #include 
        
         #include 
         
          #include 
          
           #include 
           
            using namespace std;typedef long long ll;const double eps=1e-10;double a,b,l,r;inline double F(double x){    return sqrt((a*a-x*x)/(a*a))*b;}inline double cal(double l,double r){    return (F(l)+F(r)+4*F((l+r)/2))*(r-l)/6;}double Simpson(double l,double r,double now){    double mid=(l+r)/2,p=cal(l,mid),q=cal(mid,r);    if(abs(now-p-q)