On Jun 3, 2008, at 11:17 AM, Gary Furnish wrote: > On Tue, Jun 3, 2008 at 12:11 PM, Robert Bradshaw > <[EMAIL PROTECTED]> wrote: >> >> On Jun 3, 2008, at 11:06 AM, Gary Furnish wrote: >> >>> I think we had a discussion on irc about how homsets still got used >>> for determining the result of something in parent1 op something in >>> parent2 (maybe it was with someone else?) >> >> I sure hope not. If so, that needs to change (but I'm pretty sure it >> isn't). >> > Well allegedly there is some function that computes what parent > something is in if you have parent1 op parentt2 that is new in this > system (but I can't find said function). Allegedly said function has > to use Homsets, so performance is going to be horrible(and this makes > sense, because its what I have to use now).
When a new morphism is created it needs a parent, which is a Homset that may be looked up/created at that time. This is probably what you are talking about. However, this is a single (tiny) constant overhead over the entire runtime of Sage. I'm sure this could be further optimized, but creating all the homsets ZZ -> QQ -> RR -> CC, etc. will be done long before any symbolic code gets hit. > I consider homsets to be > a gigantic flaw in coercion that absolutely have to be fixed for me to > consider using more of the coercion system in symbolics. Ironically, other people see it as a plus that coercion has been given a more categorical founding. > >>> I'm also -1 for hard-coding >>> knowledge and logic about ZZ,QQ, etc into the coercion model. I >>> am +1 >>> for hardcoding it into the elements of say, ZZ,QQ,RR and then having >>> them call the coercion model only if those hardcodes can't figure >>> the >>> situation out. >> >> That sounds much better, though I'm still not a fan. >> > Sure, its kindof ugly, but it will give us the performance we need, > and I don't see a better way to allow us to use coercions all over the > place without having performance drop to 0. One may be able to eek out a bit more performance by doing this, but it's not as if performance is awful in the current model. - 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 -~----------~----~----~----~------~----~------~--~---
