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Old 2007-08-13, 00:39   #1
davieddy
 
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You have two choices:
1) a program that takes 30 days with an x% chance of failing
2) a program that takes 40 days which is effectively reliable.

At what x do you opt for 2 rather than 1 ?

David

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Old 2007-08-13, 01:07   #2
Kevin
 
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With x% chance of failure each test run, the expected number of runs to get a correct result is 1/x. The break even point is when 30/x=40, or x=75%.

I'm fairly confident this still mostly works even with the application to GIMPS and the system of double-checks in place. However, I have a feeling many people here would place additional value on having things done right the first time and not having to deal with unnecessary double checks due to errors. If this question happens to be related to OCing, I'd only push it far enough to still get consistently correct results.
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Old 2007-08-13, 01:29   #3
davieddy
 
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Quote:
Originally Posted by Kevin View Post
With x% chance of failure each test run, the expected number of runs to get a correct result is 1/x. The break even point is when 30/x=40, or x=75%.
I don't think this is right

David

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Old 2007-08-13, 02:33   #4
Jens K Andersen
 
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Quote:
Originally Posted by Kevin View Post
With x% chance of failure each test run, the expected number of runs to get a correct result is 1/x. The break even point is when 30/x=40, or x=75%.
No. With x% chance of failure, there is 1-x% chance of a correct result. The expected number of runs to get a correct result is 1/(1-x%). The break even point is when 30/(1-x%)=40, or x=25.
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Old 2007-08-13, 05:33   #5
Orgasmic Troll
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This is assuming that you only care about the expected value
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Old 2007-08-13, 13:39   #6
R.D. Silverman
 
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Quote:
Originally Posted by Jens K Andersen View Post
No. With x% chance of failure, there is 1-x% chance of a correct result. The expected number of runs to get a correct result is 1/(1-x%). The break even point is when 30/(1-x%)=40, or x=25.
This assumes that your risk aversion function (the unit linear loss function in
Bayesian statistics) is linear. This is also known in economics as a utility
function.
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Old 2007-08-15, 13:25   #7
davieddy
 
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The (ill-disguised) follow up question is:
What exponent size reduces the reliability of
a 2048K FFT LLtest to 75% ?

David
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Old 2007-08-21, 04:51   #8
Kevin
 
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Goddamnit, I'm screwed when school starts in two weeks if I can't even get that right .
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