On Nov 19, 2008, at 10:18 AM, John H Palmieri wrote: > > The documentation for the nth_root method for finite fields (repeated > in each of the files sage/structure/element.pyx, sage/rings/ > finite_field_element.py, and sage/rings/finite_field_givaro.pyx) says > this: > > INPUT: > n -- integer >= 1 (must fit in C int type) > extend -- bool (default: True); if True, return a square > root in an extension ring, if necessary. Otherwise, > raise a ValueError if the square is not in the base > ring. > all -- bool (default: False); if True, return all square > roots of self, instead of just one. > > OUTPUT: > If self has an nth root, returns one (if all == False) or a > list of > all of them (if all == True). Otherwise, raises a > ValueError (if > extend = False) or a NotImplementedError (if extend = > True). > > The entirety of the code dealing with 'extend' is this: > > if extend: > raise NotImplementedError > > Should the 'extend' option be removed altogether, or should it be left > in with a big warning saying that it's not implemented? (Or is > someone out there willing to implement it?) > > (The same goes for the square_root method in finite_field_element.py. > The code for the sqrt method in finite_field_givaro.pyx is similar, > but the extend option, while present, isn't documented.) > > I can open up a ticket for this, but it would be nice to have a > suggestion about which direction to go in the short term -- remove the > option or document the fact that it's not implemented -- to go on the > ticket.
I think it's better to have the not implemented error. The signature of this function is modeled after the square root, and it is handy to be able to rely on it being consistent across all types. For example, if I were writing the nth root method of a power series, I might want to take the nth root of the constant coefficient, and could just pass it the extend option that I got. Removing this option means I'd have to check whether or not the extend option were valid, or get a (less clear) type error when running the code. - Robert --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-devel@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sage-devel URLs: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
