Simpson

/*
求某一段的积分
*/

double F(double x)  
{  
   ///积分函数
}  

/// 3-points simpson  


double simpson(double a,double b)  
{  
    double c=(a+b)/2;  
    return (F(a)+4*F(c)+F(b))*(b-a)/6.;  
}  

double asr(double a,double b,double eps,double A)  
{  
    double c=(a+b)/2;  
    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,L)+asr(c,b,eps/2,R);  
}  

double ASR(double a,double b,double eps)  
{  
    return asr(a,b,eps,simpson(a,b));  
}