On 23 October 2015 at 20:01, William Stein <wst...@gmail.com> wrote: > Hi Nathann, > > What problem are you solving by using immutable matrices/vectors? Why > is anything immutable for what you are doing? > > For reference, I explained above the actual problem which motivated my > writing immutable matrices/vectors for Sage in the first place. > > -- William > > On Fri, Oct 23, 2015 at 10:33 AM, Nathann Cohen <nathann.co...@gmail.com> > wrote: >>>> I do not see why matrix.row(0) should return a *copy* of the row when >>>> the matrix is immutable. >>> >>> >>> It depends on the implementation. >> >> I agree, and that was my point. As you say, under different >> circumstances (different implementation of matrices) we may have >> chosen to return 'views' on the rows of an immutable matrix instead. I >> am not proposing to do this in Sage: this would indeed require a heavy >> amount of changes. >> >> What I wanted to show is that there is nothing in the semantics of >> matrix.row(i) that says that it is necessarily a copy. In different >> software people did it differently, and that is fine too. >> >> Thus, I claim that nothing in the semantics of .row( i ) hints at a >> copy (especially for immutable matrices), and thus I do not believe >> that .row() should follow the behaviour of copy(a_matrix). >> >> In particular, I still believe that the behaviour of our objects should be >> [1]: >> - immutable+immutable = immutable >> - immutable*immutable = immutable >> - immutable_matrix.row( i ) is an immutable vector. >> >> As two examples showed, we have to get out of our way to set "back" to >> immutable objects which we expect to be from the start. Otherwise it >> is indeed very (very) hard to work with sets of immutable objects. >> >> Nathann >> >> [1] As it is the case in Python, as illustrated above with tuples. >> >> -- >> You received this message because you are subscribed to the Google Groups >> "sage-devel" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to sage-devel+unsubscr...@googlegroups.com. >> To post to this group, send email to sage-devel@googlegroups.com. >> Visit this group at http://groups.google.com/group/sage-devel. >> For more options, visit https://groups.google.com/d/optout. > > > > -- > William (http://wstein.org) > > -- > You received this message because you are subscribed to a topic in the Google > Groups "sage-devel" group. > To unsubscribe from this topic, visit > https://groups.google.com/d/topic/sage-devel/ddzJj4cceqI/unsubscribe. > To unsubscribe from this group and all its topics, send an email to > sage-devel+unsubscr...@googlegroups.com. > To post to this group, send email to sage-devel@googlegroups.com. > Visit this group at http://groups.google.com/group/sage-devel. > For more options, visit https://groups.google.com/d/optout.
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