Expected precision of Fortran FE constant evaluation

[Salvatore Filippone]

All,
May I respectfully suggest to check out this paper

R. Hanson T Hopkins
Remark on Algorithm 539: A Modern Fortran Reference Implementation for
Carefully Computing the Euclidean Norm
ACM TOMS 2017

https://dl.acm.org/citation.cfm?id=3134441
Hope this helps
Salvatore