https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100855
--- Comment #7 from Nadav Halahmi <nadavhalahmi560 at gmail dot com> --- (In reply to Dominique d'Humieres from comment #6) > On a MacOS, Corei9, 2.4Ghz, the program runs in ~1s, almost indpendtly of > the option level. > > This PR remind me an old problem in which the transcendental functions were > almost slower for REAL(4) then for REAL(8) on some Unix distros (Fedora(?), > based of "correct rounding"). > > What are your timings if you replace > > real :: sum, n, q > > with > > real(8) :: sum, n, q > > and > > sum = sum + (i ** (0.05 + n)) > > with > > sum = sum + (i ** (0.05_8 + n)) > > ? Timings for this change (notice the result was also changed): gnu: 150945570.07620683 Time = 6.303 seconds. intel: 150945570.076207 Time = 2.349 seconds. So gnu is indeed faster for real(8), but the result was changed.
