First example, nothing unexpected. Note that P is created with a tuple and Q with a list.
sage: P2 = ProjectiveSpace(GF(2),2) sage: P = P2.point((0,0,1)) sage: Q = P2.point([0,0,1]) sage: P (0 : 0 : 1) sage: Q (0 : 0 : 1) sage: P==Q True sage: P._coords [0, 0, 1] sage: Q._coords [0, 0, 1] Now the same but with "check=False": sage: P = P2.point((0,0,1),check=False) sage: Q = P2.point([0,0,1],check=False) sage: P (0 : 0 : 1) sage: Q (0 : 0 : 1) sage: P==Q False sage: P._coords (0, 0, 1) sage: Q._coords [0, 0, 1] The point is that on creation of the point, valid tuple input is converted to a list, unless check=False in which case tuples are left as tuples. This can result in wrong results. I know that users should only use "check=False" if they know what they are doing! This caught me out while writing a patch for #8193 (which I used to show a new student the ropes, but testing it led us to this weirdness!). I suggest that the point-creation function takes the trouble to always store _coords in a consistent way, presumably as a list as at present (thought surely a tuple would be better?) 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
