Re: Help with bit bashing code: differences between C and CL
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.goenninger@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-hug@lispworks.com> im Auftrag von "Marco Antoniotti (as marco dot antoniotti at unimib dot it)" <lisp-hug@lispworks.com> *Antworten an: *Marco Antoniotti <marco.antoniotti@unimib.it> *Datum: *Donnerstag, 9. November 2023 um 21:23 *An: *LispWorks <lisp-hug@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
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.antoniotti@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.goenninger@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-hug@lispworks.com> im Auftrag von "Marco Antoniotti (as marco dot antoniotti at unimib dot it)" <lisp-hug@lispworks.com> *Antworten an: *Marco Antoniotti <marco.antoniotti@unimib.it> *Datum: *Donnerstag, 9. November 2023 um 21:23 *An: *LispWorks <lisp-hug@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
participants (2)
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Marco Antoniotti -
Sabra Crolleton