利用泰勒公式计算余弦值

#include<bits/stdc++.h>
using namespace std;
double fact (int a)//计算n的阶乘
	{   double t=1.0;
		int i;
		for(i=1;i<=a;i++)
          t=t*i;
		return t;
	}
double mi (int b, double angle)//计算x的n次方
	{
		int j=1;
		double x=angle;
		for(j=1;j<b;j++)
			x=x*angle;
		return x;
	}

int main()
{
	int x,i=1,m=1,e=1;
	const double pi=3.141593;
	double p1,p2,sum=1.0,k=1,angle,shang=1;
	double fact (int);
	double mi (int b,double angle);//
	cout<<"请输入一个角度值 ";
	cin>>x;
	angle=pi*x/180;
	while(fabs(k)>=1e-7)//10的n次方的表达
	{
		e=-e;//挺妙
		m=2*i;
		p1=fact(m)*e;
		p2=mi(m,angle);
		k=p2/p1;
		shang=k;
		sum=sum+k;
		i++;
	}
	cout<<"cos("<<x<<")"<<'='<<sum<<endl;
	system("pause");
}