exp.cpp

Hamming法求级数

#include<iostream>
#include<fstream>
#include<stdio.h>
#include<stdlib.h>
using namespace std;

void computer(double x)
{
	FILE *fp;
	fp=fopen("result.txt","a");
	double k,f,f0;
	f0=0;
	for(k=1;k<100000000;k++)
	{
	    f0=f0+1/(k*(k+x));     //对于相应的x，计算f0
	}	
	f=0;
	k=1;
	while((f0-f)>0.000001)
	{
	    f=f+1/(k*(k+x));
		k++;
	}
	cout.setf(ios::fixed); 
	cout.precision(1); 
	cout.width(5);
	cout<<x;
	fprintf(fp,"%5.1f ",x);
	cout.precision(12); 
	cout.width(18);
	cout<<f0;
	fprintf(fp,"%18.12f ",f);
	cout.unsetf(ios::fixed); 
	cout.width(10);
    cout<<k<<endl<<endl;
	fprintf(fp,"%10.0f\n\n",k);
	fclose(fp);
}

int main(void)
{  
	double x,f=0;
	double f0=0.0;
	cout.width(5);
	cout<<endl<<"x";
	cout.width(11);
	cout<<"f";
	cout.width(14);
	cout<<"k"<<endl<<endl;
	for(x=0.0;x<=1.0;)
	{		
	    computer(x);
		x=x+0.1;
	}
	for(x=10.0;x<=300.0;)
	{
	    computer(x);
		x=x+10.0;
	}
	return 0;
}