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...
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
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