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2007-03-05, 08:31
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#1 |
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Mar 2007
112 Posts |
A quick question regarding iterations in Mlucas...
My question is this: is it 10M+ iterations for a mersenne prime in the Mlucas code, or is more on the order of 2 ** (exponent tested) -1 / 2?
Anyone know? Ed |
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2007-03-05, 12:08
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#2 |
"Nancy"
Aug 2002
Alexandria
2,467 Posts |
The number of LL iterations to test a Mersenne number Mp (Mp = 2^p-1) is p-2. The number of decimal digits (10 million, or some such) has (almost) nothing to do with it.
Alex |
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2007-03-05, 13:05
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#3 | |
"Lucan"
Dec 2006
England
2×3×13×83 Posts |
Quote:
"something to do with it" :) |
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2007-03-05, 13:22
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#4 |
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"Nancy"
Aug 2002
Alexandria
2,467 Posts |
That's why I wrote "almost". They are related by a constant factor, but if someone is asking about the actual number of iterations, then p-2 is the proper answer, not the number of decimal digits, even though related by a constant factor.
It would be different if the question was "how does the number of iterations increase when the Mersenne number being tested increases?" Here it would make perfect sense to reply that it grows like the number of digits, because the question only asked for proportional growth. Alex |
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2007-03-05, 14:06
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#5 |
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"Lucan"
Dec 2006
England
11001010010102 Posts |
I shall allow "almost" to excuse you:)
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