自适应 Simposion 积分

#include <cstdio>#include <iostream>#include <cmath>#include <algorithm>using namespace std;double F(double x){     //这里自定义函数    return x * x + x;}double simpson(double a,double b){  //返回区间[a,b]的三点辛普森值    double c = a + (b - a) / 2.0;    return (F(a) + 4 * F(c) + F(b)) * (b - a) / 6.0;}double asr(double a,double b,double eps,double A){  //自适应辛普森递归过程    double c = a + (b - a) / 2.0;                   //A为区间[a,b]的三点辛普森值    double L = simpson(a,c), R = simpson(c,b);    if(fabs(L + R - A) <= 15 * eps) return L + R + (L + R - A) / 15.0;    return asr(a,c,eps/2.0,L) + asr(c,b,eps/2.0,R);}double asr(double a,double b,double eps){   //自适应辛普森主过程    return asr(a,b,eps,simpson(a,b));}int main(){    cout<<asr(0,1,0.000001)<<endl;  //测试    cout<<5.0/6<<endl;              //对比    return 0;}