I hate to be spamming the forums with this, but I've been banging my head at the wall for a few hours now, and I can't really understand what is going on. Here's the full program I'm running:

```
#include <iostream>
#include "math.h"
int main() {
std::cout << sin (3.141592653589793) << "\n";
}
```

The program is returning 1.22461e-16.

Is this simply because I'm not using enough digits of pi? Then why does cos work flawlessly? Any help is greatly appreciated.