On Mon, Jul 27, 2009 at 1:11 PM, slabbe<sla...@gmail.com> wrote:
>
> I am writing some functions where I want the user to specify the
> arguments as tuples if they want. So, in the code, I am writing
> something like :
>
> arg = map(vector, arg)
>
> Of course, I want my function to work also if arg is already a list of
> vectors, but I ran into the following problem :
>
> {{{
> sage: K.<sqrt3> = QuadraticField(3); K
> Number Field in sqrt3 with defining polynomial x^2 - 3
> sage: v = vector(K, (1/2, sqrt3/2) ); v
> (1/2, 1/2*sqrt3)
> sage: v.parent()
> Vector space of dimension 2 over Number Field in sqrt3 with defining
> polynomial x^2 - 3
> sage: vector(v).parent()
> Vector space of dimension 2 over Number Field in sqrt3 with defining
> polynomial x^2 - 3
> }}}
>
> {{{
> sage: v3 = vector(K, (0, 1) )
> sage: v3.parent()
> Vector space of dimension 2 over Number Field in sqrt3 with defining
> polynomial x^2 - 3
> sage: vector(v3).parent()
> Ambient free module of rank 2 over the principal ideal domain Integer
> Ring
> }}}
>
> For vector of integers, it changes the ring for ZZ, which I doesn't
> like because I want to be able to add them (the addition of those
> vector appears to be unsupported yet by the coercion system).
>
> {{{
> sage: vector(v) + vector(v3)
> Traceback (most recent call last):
> ...
> AttributeError: 'NotImplementedType' object has no attribute
> 'natural_map'
> }}}
>
> I just created a ticket (#6643) for it and added a patch. My question
> is : Is there a reason why the vector function changes the ring of a
> vector for ZZ when possible, because my patch removes this behavior. I
> want to avoid to break something somewhere else...I can't think of a reason. I think your change is reasonable. If v is already a vector, I would expect vector(v) is v to be true. William > > See http://trac.sagemath.org/sage_trac/ticket/6643 > > My other question is : Should I create a ticket for the vector(v) + > vector(v3) coercion problem? > > Thank you, > > Sébastien Labbé > PhD Student > LaCIM, UQAM, Montréal > > > -- William Stein Associate Professor of Mathematics University of Washington http://wstein.org --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-devel@googlegroups.com To unsubscribe from this group, send email to sage-devel-unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-devel URLs: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
