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Old 2006-02-16, 08:33   #8
xilman
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May 2003
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Quote:
Originally Posted by Mystwalker
patrik:
It seems like the 45 digit level isn't needed anymore:
http://www.mersenneforum.org/showpos...59&postcount=4

Hence, I don't know whether is it efficient to do stage2 for the B1=11e6 curves. Is there someone who can update the tables to a more proper representation of the current ECM effort?
In other words:
How precise are Bruce's words, and is it possible for George to precisely update the tables accordingly?

I think this is quite an issue, as there are probably several people who waste CPU time on digit levels that are virtually impossible to have a factor.
Yes and no.

It is possible to find very large factors with very small B1 limits. It is possible to miss very small factors with very large B1 limits. There is a function that minimizes the amount of cpu time required to find factors of specified size to a given probability. This function leads to the well-known tables of B1 versus size of factors.

However, the function has a rather flat minimum and it does not matter too much whether the B1 value chosen in practice is particularly close to the optimal value. It does matter to some extent (or we wouldn't bother!) but even quite wide variations will only slow down the computation by a factor of a few.


Paul
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