Is there some implementation-specific reason not to use the standard mathematical definition of "median"? If not, I propose changing the implementation to become it.
-V On Tue, Aug 11, 2015 at 2:44 AM Nick Mathewson <ni...@alum.mit.edu> wrote: > On Mon, Aug 10, 2015 at 1:11 PM, nusenu <nus...@openmailbox.org> wrote: > > -----BEGIN PGP SIGNED MESSAGE----- > > Hash: SHA512 > > > > Hi, > > > > https://gitweb.torproject.org/torspec.git/tree/dir-spec.txt#n2028 > > > >> If 3 or more authorities provide a Measured= keyword for a router, > >> the authorities produce a consensus containing a "w" Bandwidth= > >> keyword equal to the median of the Measured= votes. > > > > a random sample from recent votes: > > > > grep 37.59.38.117 -A 3 *|grep Measured > > w Bandwidth=6869 Measured=7570 > > w Bandwidth=6869 Measured=15500 > > w Bandwidth=6869 Measured=18100 > > w Bandwidth=6869 Measured=30500 > > > > Tor says the median value is > > 15500 > > > > 2015-08-10-16-00-00-consensus: > > w Bandwidth=15500 > > > > but the median of these 4 values is actually: > > (18100+15500)/2 = 16800 > > no? > > > > Has tor a different definition of 'median' and simply takes always the > > second ordered measurement vote out of 4 votes or is there a bug in > > the spec or implementation? > > There's one misplaced throwaway sentence in dir-spec.txt: > > " All ties in computing medians are broken in favor of the smaller or > earlier item. > " > > We should bring this, and probably other things, into a "definitions" > section earlier in dir-spec.txt. Patches welcome. ;) > > -- > Nick > _______________________________________________ > tor-dev mailing list > tor-dev@lists.torproject.org > https://lists.torproject.org/cgi-bin/mailman/listinfo/tor-dev >
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