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2013-12-24, 07:48   #12
kladner

"Kieren"
Jul 2011
In My Own Galaxy!

236568 Posts

Quote:
 Originally Posted by davieddy I feel a prime coming on
That would be quite a shock.

2013-12-24, 07:56   #13
davieddy

"Lucan"
Dec 2006
England

2×3×13×83 Posts

Quote:
 Originally Posted by kladner That would be quite a shock.
Probability per day = (tests per day)*(probability of error)/250,000

2013-12-25, 04:01   #14
retina
Undefined

"The unspeakable one"
Jun 2006
My evil lair

17E616 Posts

Quote:
 Originally Posted by davieddy Probability per day = (tests per day)*(probability of error)/250,000
Isn't there a factor missing: Namely the probability of a number being prime.

Probability per day = (tests per day)*(probability of error)/250,000 * probability of being prime

[sup][sup][sup][sup]Why is the colour tag missing the u?[/sup][/sup][/sup][/sup]

2013-12-25, 04:23   #15
davieddy

"Lucan"
Dec 2006
England

2·3·13·83 Posts

Quote:
 Originally Posted by retina Isn't there a factor missing: Namely the probability of a number being prime. Probability per day = (tests per day)*(probability of error)/250,000 * probability of being prime [sup][sup][sup][sup]Why is the colour tag missing the u?[/sup][/sup][/sup][/sup]
No.
What requires clarification is the LHS.
It is the probability of a shock, namely finding a prime.

As it stands it refers to Kieren's DCs.
For my LL it would be (1/50)/450,000.

Merry Christmas!

Last fiddled with by philmoore on 2013-12-25 at 06:17 Reason: Just trying to release from moderation queue

2013-12-25, 05:45   #16
axn

Jun 2003

173 Posts

Quote:
 Originally Posted by retina Isn't there a factor missing: Namely the probability of a number being prime. Probability per day = (tests per day)*(probability of error)/250,000 * probability of being prime
What is the role of the magic number "1/250000"?

Also, it is not "Probability per day", it is "Expected primes per day" (as in, with really large values, the result can easily be > 1)

2013-12-25, 08:53   #17
davieddy

"Lucan"
Dec 2006
England

2×3×13×83 Posts

Quote:
 Originally Posted by axn Also, it is not "Probability per day", it is "Expected primes per day" (as in, with really large values, the result can easily be > 1)
THX. An important distinction.
The expected primes per day for the whole project is 1/1500.
So the probability of one or more primes per day is 1 - e=1/1500 = 1/1500.5

2013-12-25, 18:16   #18
davieddy

"Lucan"
Dec 2006
England

2·3·13·83 Posts

Quote:
 Originally Posted by davieddy The expected primes per day for the whole project is 1/1500. So the probability of one or more primes per day is 1 - e=1/1500 = 1/1500.5
@Phil: THX for allowing me to participate in the sort of mathsy fun which I enjoy.

Perhaps the 0.5 is worth looking into:

1 - e-1/X ~ 1/X - 0.5*(1/X)2
= (1/X)*(1 - 0.5*(1/X))
~ 1/(X*(1 + 0.5*(1/X))
= 1/(X + 0.5)

Wish I had done it that way first time.
Damn those calculators

D

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