I - u Calculate e

转载于 2016-01-28 19:19:00 发布 · 95 阅读

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原文链接：http://www.cnblogs.com/farewell-farewell/p/5167299.html

本文介绍了一种通过数学公式计算自然对数的底数e的近似值的方法，并提供了一个C++程序实现，该程序能够输出从n=0到n=9时e的近似值。

Description

A simple mathematical formula for e is

where n is allowed to go to infinity. This can actually yield very accurate approximations of e using relatively small values of n.

Output

Output the approximations of e generated by the above formula for the values of n from 0 to 9. The beginning of your output should appear similar to that shown below.

Sample Output

n e - ----------- 

0 1

1 2

2 2.5

 3 2.666666667 

4 2.708333333

#include<iostream>  
#include<iomanip>  
using namespace std;
double f(int n)
{
    long double a=1;
    for(int i=1;i<=n;i++)a*=i;
    return a;
}
int main()  
{  
    cout << "n e"<<endl<<"- -----------"<<endl;  
    double e=1; 
    cout<<0<<" "<<e<<endl;
    for(int i=1;i<=9;++i)  
    {  
        e+=1/f(i);  
        cout<<i<<" ";  
        if(i!=8)  cout<<setprecision(10)<<e<<endl;  
        else cout<<setprecision(10)<<e<<0<<endl;     
    }    
    //system("pause");
    return 0;
}
不难！！不要忘了long double !!!!