I agree, interval arithmetics/unums/$other_fancy_number_concept is just a start, not the end of getting reliable results. However, the roundoff errors that FPU

I agree, interval arithmetics/unums/$other_fancy_number_concept is just a start, not the end of getting reliable results. However, the roundoff errors that FPU generates are hardly controllable. In general they are not just a simple noise that cancels out on averaging. And some calculations do not do averaging at all.