Thread: Reservations
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Old 2010-11-08, 13:32   #5
R.D. Silverman
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Nov 2003

723210 Posts

Originally Posted by bdodson View Post
Raman appears to have a point, although I didn't attempt to track
down exactly which numbers Bob is referring to with "take the rest".

We've been reserving just numbers needed to keep sievers from going
idle here; 5,785M and 5,815L were reserved long after your seven current
numbers, and already completed; and 2,1870M is sieving now, with the
orphaned 2,881+ filtering. We spent quite some time on poly selection
for 3,610+ c176, which is Serge's ecm cofactor; and 5,397+ c270 is in
sims, and out of the present range of discussion (by difficulty).

The two numbers you didn't mention are 10,590M and one of the five
2LM's? Looks like 2,1930M c201.
Some thoughts.

I could probably do 2,1930M. (4-5 months of sieving; I have about
18 to 24 machines half time and 3 machines full time; availability varies).
10,590M is probably just out of range. (6-8 months of sieving; yech)

I anticipate that I will finish 2,1870L sometime in early/mid January.

I may instead turn to doing ECM work on the base 2+ numbers and the
2LM numbers. I have some questions:

What limits have you run to date on these numbers?

How long does it take to run step 1 to (say) 260M for one curve on a
number in the 250 to 300 digit range? I can only run most of my machines
at night. (6PM to 6AM). If step 1 fails to finish, is there any way to
get the code to emit the latest value for N * p, and
then restart step 1 from that point? i.e. do step 1 in stages?
I know one can emit Np when step 1 finishes, so one can do step 2

My NFS siever is set up so that it runs for a specified time, then exits.
I doubt whether GMPECM can do the same thing, although as we push
to higher limits, it might be a nice feature to add to the code.

Would you recommend using the GIMPS code for step 1, and the GMPECM
code for step 2?

Can step 2 be done in stages? It would need to dump its internal state
and this would be a LOT of data to save to the disk. How far can one
take step 2 on a 250-digit number in 12 hours?

Would 3,610+ be faster with SNFS? It is close.
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