Posts by fwjmath

1) Message boards : Science : Availability of source code (Message 3343)
Posted 10 Sep 2022 by fwjmath
Post:
I am not an expert in computational number theory, but upon reviewing a bit the present code, I think that there is not a lot of improvement we can do without algorithmical advance or changing GMP for the CPU code. For the algorithmic part, it is clear. For GMP, it is because most of the computation is arithmetic using GMP, which means that the speed mostly depends on how GMP is doing. However, GMP is a generic arbitrary precision library, meaning that there are some internal managements that are done to check which algorithm to apply. This in general gives an overhead, and probably also forbids any kind of vectorisation except those already in GMP.

One idea is, from the CUDA code we can see that there is a natural bound on numbers that are used in the computation. If they all fit in 128 bits, then gcc supports __int128. Otherwise, it might (!) help the speed by using or writing an emulated type in which the numbers fit, like the one used in the CUDA code. In this way, at least gcc would have more clues to vectorize (or not!).

fwjmath.
2) Message boards : Number crunching : Long Wu´s and short wu´s, but why? (Message 880)
Posted 10 Jun 2013 by fwjmath
Post:
According to the histogram, an important proportion of workunits finishes in no time, so why not set up a filter before generating them? Just put them up on the application, run them for 10 seconds, and this can be done on a seperated machine. This may take some time, but for example, for 819200 workunits, you need about 10 days on a good 8 core server. It will also save some bandwidth by sending out less workunits.

But since your project is running smooth all along, I think my proposal is moot. I still remember that saying: if it ain't broke, don't fix it.

Cheers,
fwjmath.
3) Message boards : Science : Project duration (Message 784)
Posted 11 Feb 2013 by fwjmath
Post:
Can you guys give an example of possible application in math research that these tables we are computing will help? I know it will be in algebraic number theory, but I would like a more concrete example. Or some reference of related research will also be fine.

Cheers,
fwjmath.
4) Message boards : Number crunching : Workunits with unreasonably high credits (Message 774)
Posted 15 Jan 2013 by fwjmath
Post:
The fix works:
http://numberfields.asu.edu/NumberFields/workunit.php?wuid=1815921

Thanks you for the quick reply and the quick fix!
5) Message boards : Number crunching : Workunits with unreasonably high credits (Message 771)
Posted 14 Jan 2013 by fwjmath
Post:
Hello everyone,

I have been crunching here for a few days. Today I happened to have a look at my result page and found quite a few strange workunits:

http://numberfields.asu.edu/NumberFields/workunit.php?wuid=1814432
http://numberfields.asu.edu/NumberFields/workunit.php?wuid=1813770
http://numberfields.asu.edu/NumberFields/workunit.php?wuid=1812336

They are so short, but granted with an improportionally great amount of credits (2,482.28 for each, less than 1 minute running time). I am feeling uneasy for earning credits without crunching. Can admins check all similar workunits and sort things straight?

I would love to know the reason of this incidence. Is there a problem on the credit system here? Could admins explain a bit how the credit system works here?

Thank you in advance for your time.

Cheers,
fwjmath.





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