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Old 2007-05-26, 20:32   #8
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"Richard B. Woods"
Aug 2002
Wisconsin USA

22·3·599 Posts

Originally Posted by axn1 View Post
Originally Posted by cheesehead
The efficiency of each choice is proportional to the ratio (chance of finding a factor)/(time to find a factor), so that ratio calculation is the one I use in the following: Prime95 will prefer combination X because 1.0%/10 (.010/10) is greater than 1.3%/15 (.013/15) or 1.5%/16 (.015/16).
You know, as I was writing that, my subconscious indicated that something was wrong, but I couldn't figure out what. I should have obeyed my impulse to add a note that I was uncertain.

Please explain what's wrong.

You cannot define efficiency of P-1 without considering the cost of an LL test.
Please explain.

I was treating the cost of an LL test as an implicit multiplication constant (constant for a specific exponent, that is -- so that it would multiply each of the calculations in my example by exactly the same number and thus need not be explicitly included -- hence my "proportional" remark).

How would you rewrite my example, or at least part of it?

(It's quite possible that when I see your explanation, I'll think, "Oh, how could I have forgotten?" or "There it is, right in the middle of my earlier posting in this thread, but I got mixed-up!" I eagerly await your explanation.)

- - -

Added: Possible source of problem: I have used the term "efficiency" privately in certain calculations for a certain concept. It's possible that:

(a) "Efficiency" has a formal meaning in the context of real, public P-1 discussion that conflicts with my private definition, or

(b) I may have a "fuzzy" private definition of "efficiency" and have gone-wrong in using it here, or

(c) I may have two separate private definitions of "efficiency" for two different contexts and mixed them up here.

My private usage: One of my private definitions of "efficiency" in this context is:

(total L-L time saved by finding a factor)
(time spent in P-1 effort to find that factor)

Another (apparently equivalent, to me) is:

(Total L-L time expected to be saved by finding factors of a given set of Mnumbers with P-1, on average given fixed B1/B2/"Available Memory" for all Mnumbers)
(Total time spent in P-1 effort to find factors of a given set of Mnumbers with P-1, on average given fixed B1/B2/"Available Memory" for all Mnumbers)

Last fiddled with by cheesehead on 2007-05-26 at 21:02
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