#include <stdlib.h>
#include <math.h>
//sin(x)=x-x^3/3!+x^6/6!-...+(-1)^(m-1)*x^(2m-1)/(2m-1)!
unsigned int fn(int n)
{
return (n == 0 || n == 1)? 1 : n * fn(n-1);
}
double Mysin(double x)
{
int m = 1, sign = 1;
double t, sum = 0;
while ( fabs(t = sign * pow(x, 2*m -1) / fn(2*m - 1)) > 1e-6)
{
sum += t;
++m;
sign *= -1;
}
return sum;
}
int main()
{
printf("%f\n", Mysin(3.14 / 2));
system("pause");
return 0;
}