龙贝格 .cpp

数值分析程序。。。。。好多程序下载 喜欢的朋友可以下 随时欢迎

#include <iostream.h>
#include <math.h>
double a,b,e,h,x,T1,T2,S,S1,S2,C1,C2,R1,R2;
int k;
double f(double x)
{
	double y;
	if(x==0)
		y=1;
	else
		y=sin(x)/x;
	return y;
}
void zihanshu ()
{
     k++;
	 h=h/2;
	 T1=T2;
	 S1=S2;
}
void main()
{
  	cout<<"请输入积分上下限a,b及误差限e的值"<<endl;
    cin>>a>>b>>e;
    h=b-a;
    T1=h*(f(a)+f(b))/2;
	for(k=1;k<=1000;k++)
	{
	    S=0;
		x=a+h/2;
		for(;x<b;)
		{
			S+=f(x);
			x+=h;
		}
		T2=T1/2+h*S/2;
		S2=T2+(T2-T1)/3;
		if(k==1)
		{
			zihanshu ();
			continue;
		}
		else
		{
			C2=S2+(S2-S1)/15;
			if(k==2)
			{
				C1=C2;
				zihanshu ();
				continue;
			}
			else
			{
				R2=C2+(C2-C1)/63;
				if(k==3)
				{
					R1=R2;
					C1=C2;
					zihanshu ();
					continue;
				}
				else if(fabs(R2-R1)>=e)
				{
					R1=R2;
					C1=C2;
					zihanshu ();
					continue;
				}					
				else
				{
                    cout<<"积分结果为"<<R2<<endl;
		        	break;
				}

			}
		}
		
	}
	
}