Julia v1.10: Performance, a new parser, and more

Again, the implementation of a trigonometric function can only work with the argument it's given. It can't know whether the argument is exact, or if not, how much error there is and how much error is acceptable in the output. And thus it has to do the best it can, assuming the argument is exact. For a quality implementation, that is; Of course an implementation can take the position that the input probably contains error, so why should it bother with being particularly accurate. But for some applications this isn't good enough.

And yes, a particularly large argument to a trigonometric function probably implies that problem should be formulated in some other way. But again, the implementation of a trigonometric function can't know that, and the best it can do is to assume the argument is exact and calculate an answer that is as accurate as possible given that assumption.

And yes, the x87 was notoriously bad with reducing large arguments. Thankfully those days are now past us, and most libc's AFAIK do argument reduction roughly per the famous(?) paper by Ng.