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-   -   Double Checking on GPU72 (https://www.mersenneforum.org/showthread.php?t=18982)

kladner 2013-12-24 07:48

[QUOTE=davieddy;362776]I feel a prime coming on:smile:[/QUOTE]

That would be quite a shock. :shock:

davieddy 2013-12-24 07:56

[QUOTE=kladner;362788]That would be quite a shock. :shock:[/QUOTE]
Probability per day = (tests per day)*(probability of error)/250,000

retina 2013-12-25 04:01

[QUOTE=davieddy;362790]Probability per day = (tests per day)*(probability of error)/250,000[/QUOTE]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 [color=red]* probability of being prime[/color]

[size=1][sup][sup][sup][sup][sup]Why is the colour tag missing the u?[/sup][/sup][/sup][/sup][/sup][/size]

davieddy 2013-12-25 04:23

[QUOTE=retina;362857]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 [COLOR=red]* probability of being prime[/COLOR]

[SIZE=1][sup][sup][sup][sup][sup]Why is the colour tag missing the u?[/sup][/sup][/sup][/sup][/sup][/SIZE][/QUOTE]
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!

axn 2013-12-25 05:45

[QUOTE=retina;362857]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 [color=red]* probability of being prime[/color]
[/QUOTE]

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)

davieddy 2013-12-25 08:53

[QUOTE=axn;362861]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)[/QUOTE]
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[SUP]=1/1500[/SUP] = 1/1500.5

:smile:

davieddy 2013-12-25 18:16

[QUOTE=davieddy;362866]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[SUP]=1/1500[/SUP] = 1/1500.5[/QUOTE]
@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[SUP]-1/X[/SUP] ~ 1/X - 0.5*(1/X)[SUP]2[/SUP]
= (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:smile:

D


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