I have a Go library implementing double-double arithmetic (and also exponentials, logarithms, trigonometry...): https://github.com/ncruces/dbldbl https://github

I have a Go library implementing double-double arithmetic (and also exponentials, logarithms, trigonometry...): https://github.com/ncruces/dbldbl https://github.com/ncruces/dbldbl Mostly useless, but was quite fun to write.