45 lines
919 B
C++
45 lines
919 B
C++
#include <iostream>
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#include <cstdio>
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#include <cstring>
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#include <algorithm>
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#include <string>
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#include <cmath>
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#include <cstdlib>
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#include <vector>
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#include <queue>
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#include <set>
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#include <map>
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using namespace std;
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double a,b,l,r;
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double F(double x)
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{
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return b*sqrt((1-x/a)*(1+x/a));
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}
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double simpson(double a,double b)
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{
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double c=(a+b)/2;
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return (F(a)+4*F(c)+F(b))*(b-a)/6.;
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}
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double asr(double a,double b,double eps,double A)
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{
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double c=(a+b)/2;
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double L=simpson(a,c),R=simpson(c,b);
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if(fabs(L+R-A)<=15*eps) return L+R+(L+R-A)/15.0;
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return asr(a,c,eps/2,L)+asr(c,b,eps/2,R);
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}
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double ASR(double a,double b,double eps)
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{
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return asr(a,b,eps,simpson(a,b));
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}
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int main()
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{
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int T_T;
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scanf("%d",&T_T);
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while(T_T--)
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{
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scanf("%lf%lf%lf%lf",&a,&b,&l,&r);
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printf("%.3lf\n",2.*ASR(l,r,1e-6));
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}
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return 0;
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}
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