#include <iostream>
#define PI 3.1415926
double sin(double x)
{
	double s;
	if(x>2*PI)
		x-=2*PI*(int)(x/PI/2);
	if(x*2>PI)
		if(x<PI)
			s=sin(PI-x);
		else if(x*2<PI*3)
			s=-sin(PI-x);
		else
			s=-sin(x);
	else
	{
		double a=x,b=1,t,r=0,xx=x*x,s=1,i=3;
		do
		{
			t=a/b;
			r+=t*s;
			a=a*xx;
			b=b*i;
			i+=2;
			s=s==1?-1:1;
		}while(t>1e-5);
		return r;
	}
	return s;
}
int main()
{
	using namespace std;
	double x;
	cout<<"请输入x值：";cin>>x;
	cout<<"sin(x)="<<sin(x);
	return 0;
}