Hi Marco, Same results as Frank (diverging starting at j = 21) using SBCL 2.3.8 and gcc 13.2.1 on an AMD Ryzen 5 3600 6-Core Processor running Linux
Sabra On Thu, Nov 9, 2023 at 8:53 PM Marco Antoniotti <marco.antonio...@unimib.it> wrote: > Thanks. > > This is weird. The C and Fortran versions seem to agree. > > Marco > > > > > On Thu, Nov 9, 2023 at 9:49 PM Frank Gönninger | Gönninger B&T < > frank.goennin...@goenninger.net> wrote: > >> Hi Marco, >> >> >> >> on AllegroCL 11.0 beta Enterprise Edition I get diverging results >> starting at j = 21… >> >> >> >> Lisp: j = 21; ss = 0.00028959847986698150 >> >> C: j = 21; ss = 0.00028959847986698151 >> >> >> >> FWIW … >> >> >> >> Best, >> >> Frank >> >> >> >> *Von: *<owner-lisp-...@lispworks.com> im Auftrag von "Marco Antoniotti >> (as marco dot antoniotti at unimib dot it)" <lisp-...@lispworks.com> >> *Antworten an: *Marco Antoniotti <marco.antonio...@unimib.it> >> *Datum: *Donnerstag, 9. November 2023 um 21:23 >> *An: *LispWorks <lisp-...@lispworks.com>, Discussion list for Common >> Lisp professionals <pro@common-lisp.net> >> *Betreff: *Help with bit bashing code: differences between C and CL >> >> >> >> Dear all, >> >> >> >> I am hitting a wall with the attached code in CL and C versions. For >> those interested, this is code lifted from Knuth's pages on random number >> generation (https://www-cs-faculty.stanford.edu/~knuth/programs.html#rng >> ). >> >> The problem is that there is a discrepancy in the "problem" loop between >> the CL and the C and I cannot figure out why, although the culprit may be >> that CL does not have "proper" 64 bits ints. >> >> I am running on LW 8.x on an Intel Mac. I have not tried on other CL >> implementations/platforms. I compile the C code with clang (Apple clang >> version 15.0.0 (clang-1500.0.40.1) >> >> >> >> If you run the code, you will see that the discrepancy appears at 'j = >> 14' in the loop. >> >> >> >> What gives? >> >> Thanks >> >> Marco >> >> >> >> >> >> >> -- >> >> Marco Antoniotti, Professor tel. +39 - 02 64 48 79 01 >> DISCo, Università Milano Bicocca U14 2043 http://dcb.disco.unimib.it >> Viale Sarca 336 >> I-20126 Milan (MI) ITALY >> >
