#6643: vector function changes the ring of a vector for ZZ when possible
----------------------------+-----------------------------------------------
Reporter: slabbe | Owner: slabbe
Type: defect | Status: new
Priority: major | Milestone: sage-4.1.1
Component: linear algebra | Keywords:
Reviewer: | Author:
Merged: |
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The following works fine, i.e vector function doesn't change the ring of
the input vector :
{{{
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
}}}
For rationals coordinates, it is also OK :
{{{
sage: v2 = vector(K, (1/2, 3/2) ); v2
(1/2, 3/2)
sage: v2.parent()
Vector space of dimension 2 over Number Field in sqrt3 with defining
polynomial x^2 - 3
sage: vector(v2).parent()
Vector space of dimension 2 over Number Field in sqrt3 with defining
polynomial x^2 - 3
}}}
But, for integers, it changes the ring for ZZ :
{{{
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
}}}
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...this could be another ticket...) :
{{{
sage: v + v3
(1/2, 1/2*sqrt3 + 1)
sage: vector(v) + vector(v3)
ERROR: An unexpected error occurred while tokenizing input
The following traceback may be corrupted or invalid
The error message is: ('EOF in multi-line statement', (1052, 0))
Traceback (most recent call last):
...
/home/slabbe/sage-4.1/local/lib/python2.6/site-
packages/sage/modules/free_module.pyc in __cmp__(self, other)
3806 if not c: return c
3807 try:
-> 3808 if self.base_ring().is_subring(other.base_ring()):
3809 return -1
3810 elif
other.base_ring().is_subring(self.base_ring()):
/home/slabbe/sage-4.1/local/lib/python2.6/site-packages/sage/rings/ring.so
in sage.rings.ring.Ring.is_subring (sage/rings/ring.c:4724)()
AttributeError: 'NotImplementedType' object has no attribute 'natural_map'
}}}
I will also ask on sage-devel if there is a reason why the vector function
changes the ring of a vector for ZZ when possible.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/6643>
Sage <http://sagemath.org/>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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