On Thursday 11 July 2002 03:43, George Pantazopoulos wrote: > Hey all, > If an overclocked machine is producing erroneous results, how much harm > does it to the project as a whole? Can it miss the next Mersenne prime? > Will the rest of the group assume that there is officially no Mersenne > prime at the missed location and not double-check? > (Apart from the fact that there are lots of reasons other than overclocking why a result might be in error!)
That's the whole point of double-checking.... There IS a VERY SMALL chance that a double-checked result would be wrong. This will happen if BOTH runs go wrong and the final residual is the same. The chance of this happenning with independent random errors is obviously less than 1 in 2^64; this is about the same chance that the same balls will be drawn four weeks running in a 6/49 lottery game, so we don't worry too much about it. The chance of missing a prime is much smaller than that, because the wrong result would have to belong to a number which really is prime. However, there are a number of exponents where one or other of the runs was made with an old client which reported 16 (sometimes even less) biys of the residual. Clearly there is a much higher chance that one of these might be wrong. For some time, some of us have been systematically working our way through these running a triple-check, but there are still a few thousand left. This is an ideal project for systems too slow to be useful otherwise, as the remaining exponents are all less than 2 million (in fact about 40% of them are less than 800,000). Anyone interested in contributing, please e-mail me directly. Regards Brian Beesley _________________________________________________________________________ Unsubscribe & list info -- http://www.ndatech.com/mersenne/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
