r.cpp

这是一个计算方法的编程。是关于复化梯形积分的程序

#include <iostream.h>
#include <math.h>
double E0=0.0001;

void main(void)/*复化梯形积分*/

{
   double fna(double x);
   double m=0,n=2;
   double y;
   double integral(double a,double b );
   y=integral(m,n);
   cout<<"积分值y="<<y<<endl;
}
  double fna(double x)
  {
   double f;
    f=x*2;
    return(f);
  }
  double integral(double a,double b )
  {
      int i,n=2;
      double s0,s1=0,h,p=0,q;
      s0=(fna(a)+fna(b))/2;
             cout<<"s0="<<s0<<endl;
      
       for(i=1;i<=n;i+=2) 
           h=(b-a)/n;
      s1+=fna(a+i*h);
              cout<<"s1="<<s1<<endl;
       q=h*(s0+s1);
              cout<<"q="<<q<<endl;
         
       if (abs(p-q)<E0) 
           cout<<"q="<<q<<endl;
       else
           p=q;
           n=2*n;
      
          
      
      return(q);
  }