Not sure what’s going on but Julia is definitely not switching to arbitrary precision without being explicitly asked to do so. That would be very unjulian. I’m

Not sure what’s going on but Julia is definitely not switching to arbitrary precision without being explicitly asked to do so. That would be very unjulian. I’m not at a computer or I’d investigate. One hypothesis based on some other comments is that getting the wrong answer (especially when using expm1) may be due to unsafe C compiler flags, which Julia does not apply by default. Just a guess though. Update from reading more comments: it seems that Rust and C via godbolt without questionable C flags also don’t fail like this. So I wonder if John hadn’t compiled the code with fast-math on, which will allow me the compiler to give all kinds of wrong answers.