Ondrej Pokorny via fpc-devel <fpc-devel@lists.freepascal.org> schrieb am Di., 29. Nov. 2022, 11:39:
> Am 29.11.2022 um 11:08 schrieb Sven Barth via fpc-devel: > > J. Gareth Moreton via fpc-devel <fpc-devel@lists.freepascal.org> schrieb > am Di., 29. Nov. 2022, 10:09: > >> Surely that's a bug in the comparison functions that should be fixed and >> not something that can be blamed on introsort. If a comparison function >> is faulty, then pretty nuch any sorting algorithm can be considered to >> have unpredictable behaviour. >> > > This *can* be blamed on IntroSort, because Stability (order of equal > elements is kept) is an attribute of sorting algorithms and IntroSort is > *not* considered stable while QuickSort *can* be stable depending on the > implementation and ours *is*. > > If for two elements [a, b] the comparison function returns > a<b=true and b<a=true > > then the problem is not in stability or any other feature of the sorting > algorithm but in the comparison function indeed. Or am I missing something? > For such a comparison function the issue is indeed in the comparison function, but Nikolay also mentioned "a<b=false and b<a=false" which is the case for equal elements. Regards, Sven >
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