大家好！急需数字积分方面的源程序，请大家给予指导！

#include <iostream.h>
#include <math.h>
#include <iomanip.h>
class F
{
public:
    virtual double operator()(double x) const=0;
};
class Fun: public F
{
public:
    double operator()(double x)const
    {
        return log(1.0+x)/(1.0+x*x);
    }
};
class Integ
{
public:
    virtual double operator()(double a,double b,double eps) const=0;
};
class Trapz:public Integ
{
public:
    Trapz(const F &pf):f(pf){};
    double operator()(double a,double b,double eps) const;
private:
    const F &f;
};
double Trapz::operator()(double a,double b,double eps)const
{
    int done(0);
    int n;
    double h,Tn,T2n;
    n=1;
    h=b-a;
    Tn=h*(f(a)+f(b))/2;
    while(!done)
    {
        double temp(0.0);
        for(int k=0;k<n;k++)
        {
            double x=a+(k+0.5)*h;
            temp+=f(x);
        }
        T2n=(Tn+h*temp)/2;
        if(fabs(T2n-Tn)<eps)  
            done=1;
        else
        {
             Tn=T2n;
             n*=2;
             h/=2;
        }
    }
    return T2n;
}
void main()
{
    Fun f;
    Trapz trapz1(f);
    cout<<"TRAPZ int:"<<setprecision(7)<<trapz1(0,2,1e-7)<<endl;
 
}
这个程序是求一个函数的积分