GMP used during 3 and a half years to solve MIT's LCS35

Bernard Fabrot bfabrot at
Tue Apr 30 21:34:01 UTC 2019


I made it clear everywhere it was thanks to GMP I solved this so fast: GMP
is hence mentioned in the MIT press release and so in all the articles
based on that press release.

Credits where it's due : )

> I got it to that you are using an average of about 4000 cycles per
iteration, whereas the other guys are about 20 times faster.

Yup close.

Core i7-7600 running at 3.4 Ghz but turbo-boosting to 3.9 or 4.0 Ghz when
only one or two cores are at 100%.  About 22 minutes for 1 billion

So I was a bit slower than that: I'd say about 5150 cycles per iteration,
something like that (unless my math is off).

Funny development: now that the story is out about LCS35 being solved, a
3rd team came up mentioning they were at 75%. But these guys are building
an actual ASIC and are using a FPGA to validate their ASIC design (from
what I understand).

It's all very exciting!

> I presume you had some recovery system in case of a reboot.

Yes of course. Every one billion iteration I'd save the intermediate result
to a text file and I'd regularly backup the text files to many different
places / medium.

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