这个sin（x）函数怎么用c语言表达

Question

Answer 1

#include<stdio.h>
#include<math.h>
double sin(double);
double nResult(double,double);
int main()
{
    double x=0;
    scanf("%lf",&x);
    printf("sin(%lf)=%lf\n",x,sin(x));
    return 0;
}
 
double sin(double x)
{
    //sin(x)=x-x^3/3!+x^5/5!-x^7/7!+……+(-1)(n^2n+1)/(2n+1)!+……
    int i=0;
    double result=0,n=0;
    while( fabs( n=nResult(x,2*++i-1) ) > 0e-5 )//绝对值大于10^-5次方就循环
        result+=(i%2==1)?n:-n;
    return result;
}
 
double nResult(double x,double n)
{
    return n==1?x:nResult(x,n-1)*x/n;
}