下面一个程序求一个函数
当r*r<=s*s时， k=sqrt(sin(r)*sin(r)+sin(s)*sin(s))
当r*r>s*s时， k= sin(r*s)/2;
程序编译时没错，运算结果不对，请帮忙看看
#include<iostream>
#include<cmath>
#include<cstdlib>
using namespace std;

long factorial(int n);
double tSin(double x);

int main()
{
    double r;
    double s;
    double result;
    cout<<"Enter r and s:"<<endl;
    cin>>r>>s;
    if(r*r <= s*s)
        result = sqrt(tSin(r)*tSin(r) + tSin(s)*tSin(s));
    else
        result = tSin(r * s) / 2;
    cout<<"result= "<<result;
    return 0;
}
long factorial(int n)
{
    long f;
    if(n < 0)
    {
        cout<<"Data error,please enter again!"<<endl;
        exit(-1);
    }
    else if(n == 0)
        f = 1;
    else
        f = factorial(n - 1) * n;
    return f;
}
double tSin(double x)
{
    int den = 1;//fenmu
    double num = x;//fenzi
    double sqr = x  * x;
    double sinResult;
    int flag = -1;
    double fun = num / den;
    while(fabs(fun) > 1e-6)
    {
        sinResult += fun;
        num *= sqr;
        den = factorial(den + 2) * flag;
        fun = num / den;
    }
    return sinResult;
}