On Tue, Oct 14, 2014 at 10:33 PM, Charles R Harris <charlesr.harris@gmail.com> wrote:
On Tue, Oct 14, 2014 at 11:50 AM, Nathaniel Smith <njs@pobox.com> wrote:
On 14 Oct 2014 18:29, "Charles R Harris" <charlesr.harris@gmail.com> wrote:
On Tue, Oct 14, 2014 at 10:57 AM, Nathaniel Smith <njs@pobox.com> wrote:
On 4 Oct 2014 22:17, "Stéfan van der Walt" <stefan@sun.ac.za> wrote:
On Oct 4, 2014 10:14 PM, "Derek Homeier" <derek@astro.physik.uni-goettingen.de> wrote:
+1 for an order=2 or maxorder=2 flag
If you parameterize that flag, users will want to change its value (above two). Perhaps rather use a boolean flag such as "second_order" or "high_order", unless it seems feasible to include additional orders in the future.
Predicting the future is hard :-). And in particular high_order= would create all kinds of confusion if in the future we added 3rd order approximations but high_order=True continued to mean 2nd order because of compatibility. I like maxorder (or max_order would be more pep8ish I guess) because it leaves our options open. (Similar to how it's often better to have a kwarg that can take two possible string values than to have a boolean kwarg. It makes current code more explicit and makes future enhancements easier.)
I think maxorder is a bit misleading. The both versions are second order in the interior while at the ends the old is first order and the new is second order. Maybe edge_order?
Ah, that makes sense. edge_order makes more sense to me too then - and we can always add interior_order to complement it later, if appropriate.
The other thing to decide on is the default. Is the 2nd order version generally preferred (modulo compatibility)? If so then it might make sense to keep it the default, given that there are already numpy's in the wild with that version, so we can't fully guarantee compatibility even if we wanted to. But what do others think?
I'd be inclined to keep the older as the default and regard adding the keyword as a bugfix. I should have caught the incompatibility in review.
I don't have any code that uses gradient, so I don't have a great sense of the trade-offs here. - Usually if we have a change that produces increased accuracy, we make the increased accuracy the default. Otherwise no-one ever uses it, and everyone gets less accurate results than they would otherwise. (I don't have a great sense of how much this change affects accuracy though.) - If the change in output per se is a serious problem for people, then it's not one we can fix at this point -- 1.9.0 is out there and people are using it anyway, so those who have the problem already need to take some affirmative action to fix it. (Also, it's kinda weird to change a function's behaviour and add a new argument in a point release!) So I'd like to hear from people affected by this -- would you prefer to have the 2nd order boundary calculations by default, you just need some way to workaround the immediate problems in existing code? Or do you prefer the old default remain the default, with 2nd order boundary calculations something that must be requested by hand every time? -n -- Nathaniel J. Smith Postdoctoral researcher - Informatics - University of Edinburgh http://vorpus.org