1 //这里f()为被积函数，输入a,b为积分上下限，
2 //eps为计算精度[这里要注意假收敛，一般设小一点好]
3 #include <iostream>
4 #include <cmath>
5 #define eps 1e-6
6 using namespace std;
7 double f(double x){
8 return sqrt(1+cos(x)*cos(x));
9 }//被积函数
10 double Sn(double a,double b,double n){
11 double h=(a+b)/(2*n);
12 double sum=0;
13 for(int k=1;k<=n;k++){
14 sum+=2*f(a+(2*k-1)*h);
15 sum+=f(a+2*k*h);
16 }
17 sum=(sum*2+f(a)-f(b))*h/3;
18 return sum;
19 }//辛普森公式
20 double Solve(double a,double b){
21 int i=1;
22 double S1n=Sn(a,b,i);
23 double S2n=Sn(a,b,2*i);
24 while(fabs(S1n-S2n)>eps){
25 cout<<"n = "<<i<<" S1 = "<<S1n<<" S2 = "<<S2n<<'\n';
26 i++;
27 S1n=S2n;
28 S2n=Sn(a,b,2*i);
29 }
30 return S2n;
31 }
32 int main(){
33 cout<<Solve(0,48)<<'\n';
34 }
