On 13-Feb-08, at 2:15 PM, William Stein wrote:
> > On Feb 13, 2008 2:09 PM, Nick Alexander <[EMAIL PROTECTED]> wrote: >> >> >> On 13-Feb-08, at 12:28 PM, William Stein wrote: >> >>> >>> On Feb 13, 2008 9:57 AM, Nick Alexander <[EMAIL PROTECTED]> >>> wrote: >>>> >>>> >>>> On 13-Feb-08, at 6:06 AM, John Cremona wrote: >>>> >>>>> >>>>> I just discovered sage.rings.arith.discrete_log_generic(), not >>>>> until >>>>> after implementing a similar function for elliptic curves over >>>>> finite >>>>> fields (patch to be submitted before too long). I thought it >>>>> was a >>>>> pity that we cannot apparently use the same code for dlogs in an >>>>> additive group (as in what I just wrote) and a multiplcative >>>>> one (as >>>>> in discrete_log_generic()). Could we? >>>> >>>> At this time, not easily. >>> >>> I think it would be trivial. Just pass in a function of two >>> arguments called >>> "mul" instead of using "*". It's the same way Python's sort works. >>> (One should probably also pass in a pow function.) >> >> John also needs identity and inverses, which requires passing in >> three or functions. Or, more likely a struct, which in an OO >> language, I call an object. >> >> To me, that means you're writing a special purpose "abstract group" >> wrapper for discrete logs, which is fine. But I believe the heavier >> categorical stuff is intended to make doing this much more general >> and pervasive throughout the system. Doing one instance ad-hoc is >> easy; doing the general case is not easy (imho). > > And doing the general case is easier if you do one instance :-) Indeed! I will referee the patch. Could I suggest a BlackboxGroupInterface class providing the basic machinery, and an _as_blackbox_group in each ring/group that returns an instance of such a class? Would the category people care to comment? Nick --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
