C++ pow函数实现 ~~晚间划水

用泰勒展开实现pow函数，实际效果还不如直接循环

但是这对于初步理解泰勒展开还是有一点帮助的

 1 #include<iostream>
 2 #include<cmath>
 3 using namespace std;
 4 
 5 double exp_x(double x){
 6     double p=x,ans=1;
 7     for(int i=1;i<=10000;++i){
 8         ans+=p;
 9         p=p*x/(i+1);
10     }
11     return ans;
12 }
13 
14 double log_e(double x){
15     if(x<=0){
16         puts("Error");
17         exit(0);
18     }
19     double ans=0;
20     while(x>=1){
21         ans=ans+1;
22         x/=exp_x(1);
23     }
24     double p=x-1,sgn=1;
25     for(int i=1;i<=10000;++i){
26         ans+=sgn*p/i;
27         p=p*(x-1);
28         sgn=-sgn;
29     }
30     return ans;
31 }
32 
33 double power(double x,double y){return exp_x(log_e(x)*y);}
34 
35 int main(){
36     double x,y;
37     while(cin>>x>>y&&(x||y)){
38         cerr<<power(x,y)<<endl;
39         cerr<<pow(x,y)<<endl;
40     }
41     system("pause");
42     return 0;
43 }