龙贝格算法求定积分 C++ --数值分析_蜂蜜柚子茶的博客

完整代码如下：

#include<iostream>
#include<math.h>
using namespace std;
double fun(double x)
{
    //return sin(x)+x*cos(x);//原函数
    return sin(x)/x;
}
double romberg(double a,double b,double(*f)(double),double eps){//上下限、被积函数、精度
    double T1,T2,S1,S2,C1,C2,R1,R2,S,x;
    double h=b-a;
   T1=h/2*((*f)(a)+(*f)(b));
  // cout<<T1;
   int k=0;
   while(1)
{   //k++;
    S=0;
    x=a+h/2;
   do
   {
       S=S+(*f)(x);
       x=x+h;
   }while(x<b);
   //if s>=b
   T2=T1/2+h/2*S;
  // cout<<T2;
   //if(fabs(T2-T1)<eps) return T2;
   S2=T2+1/3*(T2-T1);
   if(k==1)
   {
       k++;
       h=h/2;
       T1=T2;
       S1=S2;
    //   cout<<S2;
    continue;
   }
   C2=S2+1/15*(S2-S1);
   if(k==2)
   {
       k++;
       h=h/2;
       T1=T2;
       S1=S2;
       C1=C2;
       continue;
   }
   R2=C2+1/63*(C2-C1);
   if(k==3)
   {
       k++;
       h=h/2;
       T1=T2;
       S1=S2;
       C1=C2;
       R1=R2;
       continue;
   }
   if(fabs(R2-R1)<eps)
   {
       cout<<k<<endl;
    return R2;
   }
       k++;
       h=h/2;
       T1=T2;
       S1=S2;
       C1=C2;
       R1=R2;
       continue;
}

}
int main()
{
    double eps,a,b;
    cout<<"请输入积分上下限: "<<endl;
    cin>>a>>b;
    cout<<"请输入精度："<<endl;
    cin>>eps;
    double ans=romberg(a,b,*fun,eps);
    cout<<ans;
    return 0;
}
#include<iostream>
#include<ma