ErrorFreeArith.jl <https://github.com/J-Sarnoff/ErrorFreeArith.jl> offers error-free transformations not (yet?) included in the ErrorFreeTransforms package by dsiem.
These operations convey the usual arithmetic result accompanied by a residual value that is usually lost to rounding. This gives the correct value at twice the working precision (correctly rounded for +,-,*,/; still 1/(1/x) = x or x ± ulp(x)).
