I emailed Nick Higham asking about Unums a year and a half ago. Hopefully he doesn’t mind me quoting from private email: > I have Gustafson's book and have rea

I emailed Nick Higham asking about Unums a year and a half ago. Hopefully he doesn’t mind me quoting from private email: > I have Gustafson's book and have read a lot of it. I don't yet know what to make of it. [..] His Unum system is a completely different way of working to floating point, so all I can say is that standard error analysis techniques will probably not be applicable. > The book does not yet seem to have atttracted much attention in the numerical analysis community.