That doesn't surprise me, as before floats are involved you need to transform the series into something you can compute (doing this by hand is a good way to und

That doesn't surprise me, as before floats are involved you need to transform the series into something you can compute (doing this by hand is a good way to understand what's going on underneath). https://developers.redhat.com/blog/2015/01/02/improving-math-performance-in-glibc https://developers.redhat.com/blog/2015/01/02/improving-math... gives a basic intro to how these functions are actually implemented, and we can if you compute exp(x) - 1 near 0 that 1 + (small stuff) - 1 is always going to be a problem (it'd be nice if we had a sufficiently smart compiler that could understand how to inline these things, but then it'd probably do surprising things as well).