> > Good point. It turns out to be much harder if we don't just assume numbers. > I guess one way to do it would be to construct a parse tree using the > python parsing, except, of course, that semicolons make [1 2 3; 4 5 6] not > valid syntax, though I suppose we could replace semicolons and newlines with > "][" and then filter out empty lists. Spaces also would be problem in > constructing a parse tree, since [1 2] isn't valid syntax. > > So yeah, expanding the preparser for this very common situation (easily > creating a doubly-nested list) is starting to look more like a good idea. > > If we expanded the preparser, would [1 2; 3 4] create a matrix or just a > doubly-nested list? I can see arguments both ways, and this is where Nils > point really hits home. Almost always, I want matrices over QQ, but [1 2; 3 > 4] won't naturally create a matrix over QQ. On the other hand, typing > matrix(QQ, [1 2; 3 4]) seems to take the fun out of the syntax, since it's > not too much easier than matrix(QQ, [[1,2], [3,4]])
Some of the code used to manage this: sage: M = matrix(2,2,[1,2,3,4]) sage: PM = pari(M) sage: PM [1, 2; 3, 4] sage: PM.sage() [1 2] [3 4] could perhaps be reused like this: sage: s = "[1,2;3,4]" sage: pari(s).sage() [1 2] [3 4] sage: s = "[1.1,2.2;3.3,4.4]" sage: pari(s).sage() [1.1000000000000000000000000000000000000 2.2000000000000000000000000000000000000] [3.3000000000000000000000000000000000000 4.4000000000000000000000000000000000000] so we are using the pari parser to construct a pari matrix, which then knows how to be converted into sage. John -- To post to this group, send an email to sage-devel@googlegroups.com To unsubscribe from this group, send an email to sage-devel+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-devel URL: http://www.sagemath.org
