On Saturday, June 10, 2017 at 7:05:49 PM UTC-7, David Joyner wrote: > > On Thu, Jun 8, 2017 at 10:49 PM, John H Palmieri <[email protected] > <javascript:>> wrote: > > > > > > On Thursday, June 8, 2017 at 5:16:15 PM UTC-7, David Joyner wrote: > >> > >> Hi all: > >> > >> This is kind of a newbie question, as I'm not an expert on simplicial > >> complexes. It's also a minor technical issue on the documentation, not > >> the code. > >> > >> I'm trying to debug some code of mine and, on reading the > >> documentation for chain_complex on > >> > >> > http://doc.sagemath.org/html/en/reference/homology/sage/homology/simplicial_complex.html, > > > >> found this: "The rows and columns of the boundary matrices are indexed > >> by the lists given by the n_cells() method, which by default are > >> sorted." On the other hand, the documentation for n_cells has this > >> statement: "Sort the list if the argument sort is True. If sort is > >> None (the default), then sort depending on the value of the > >> sort_facets parameter (from the initialization of the simplicial > >> complex)." However, the sort_facets parameter (unless I'm mistaken) > >> does not sort the individual faces but rather sorts the vertices in > >> each facet. > > > > > > The documentation means that if "sort_facets" was True originally, then > > n_cells will also sort its result before returning it. ("then sort > depending > > on the value of the sort_facets parameter": so if sort_facets was True, > then > > n_cells should also sort. It doesn't mean "sort using the effect of the > > sort_facets parameter", but sort depending on its value, which is True > or > > False. This could be made clearer, I guess.) > > > > > To be clear, I am getting different computations using the same sage > computations on different machines. One (recent, but used, linux) > machine consistently gives ones result, the other gives (randomly?) > several others. The "other" (a 8 yr old, a mac with possibly memory > issues) machine gives different results. I'm not saying your methods > are machine dependent, just that *for me* they seem to be. > > To be clear, these "inconsistent" computations take at least one day. > The "toy" (consistent) examples are okay. >
That's strange. Are you just getting different orders when you sort, or different answers for homology? Are the answers consistent on each machine? What type of object are the vertices? > > > I don't know if there is ever a good reason to specify > sort_facets=False. > > Maybe we should deprecate it? > > > >> > >> In my code, I expected the faces of a fixed dimension to > >> be returned as a deterministic sorted list not a set whose ordering > >> could be random. Now, it *does* seem as though the faces are sorted. > >> It's just that, to me, the documentation of n_cells doesn't make that > >> clear. > >> > >> I'm asking if I'm mis-understanding something here or not. > >> > >> - David Joyner > > > > > > -- > > John > > > > > > -- > > You received this message because you are subscribed to the Google > Groups > > "sage-support" group. > > To unsubscribe from this group and stop receiving emails from it, send > an > > email to [email protected] <javascript:>. > > To post to this group, send email to [email protected] > <javascript:>. > > Visit this group at https://groups.google.com/group/sage-support. > > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "sage-support" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/sage-support. For more options, visit https://groups.google.com/d/optout.
