#4539: plural wrapper
---------------------------+------------------------------------------------
Reporter: burcin | Owner: OleksandrMotsak, AlexanderDreyer
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-4.6
Component: algebra | Keywords:
Author: | Upstream: N/A
Reviewer: | Merged:
Work_issues: |
---------------------------+------------------------------------------------
Comment(by nthiery):
Is it possible at this stage to define non commutative polynomial rings
over QQ['q'].fraction_field()?
I got an error with what I tried:
{{{
sage: K = QQ['q'].fraction_field()
q = K.gen()
F.<x,y,ex,ey> = FreeAlgebra(K,4)
W = F.g_algebra({ex*x: x*(1+ex),ey*y:y*(1+ey)})
sage: ------------------------------------------------------------
Traceback (most recent call last):
File "<ipython console>", line 1, in <module>
File "/opt/sage-4.5.2/local/lib/python2.6/site-
packages/sage/algebras/free_algebra.py", line 547, in g_algebra
return NCPolynomialRing_plural(base_ring, n, ",".join([str(g) for g in
self.gens()]), c=cmat, d=dmat, order=order, check=check)
File "plural.pyx", line 223, in
sage.rings.polynomial.plural.NCPolynomialRing_plural.__init__
(sage/rings/polynomial/plural.cpp:3772)
File "matrix0.pyx", line 1520, in sage.matrix.matrix0.Matrix.change_ring
(sage/matrix/matrix0.c:7670)
File "/opt/sage-4.5.2/local/lib/python2.6/site-
packages/sage/matrix/matrix_space.py", line 405, in __call__
return self.matrix(entries, copy=copy, coerce=coerce, rows=rows)
File "/opt/sage-4.5.2/local/lib/python2.6/site-
packages/sage/matrix/matrix_space.py", line 1136, in matrix
return self.__matrix_class(self, entries=x, copy=copy, coerce=coerce)
File "matrix_generic_dense.pyx", line 93, in
sage.matrix.matrix_generic_dense.Matrix_generic_dense.__init__
(sage/matrix/matrix_generic_dense.c:2321)
File "/opt/sage-4.5.2/local/lib/python2.6/site-
packages/sage/rings/polynomial/multi_polynomial_ring.py", line 468, in
__call__
c = self.base_ring()(x)
File "parent.pyx", line 859, in sage.structure.parent.Parent.__call__
(sage/structure/parent.c:6407)
File "coerce_maps.pyx", line 82, in
sage.structure.coerce_maps.DefaultConvertMap_unique._call_
(sage/structure/coerce_maps.c:3108)
File "coerce_maps.pyx", line 77, in
sage.structure.coerce_maps.DefaultConvertMap_unique._call_
(sage/structure/coerce_maps.c:3010)
File "/opt/sage-4.5.2/local/lib/python2.6/site-
packages/sage/rings/fraction_field.py", line 467, in _element_constructor_
coerce=coerce, reduce = self.is_exact())
File "fraction_field_element.pyx", line 120, in
sage.rings.fraction_field_element.FractionFieldElement.__init__
(sage/rings/fraction_field_element.c:1934)
File "parent.pyx", line 859, in sage.structure.parent.Parent.__call__
(sage/structure/parent.c:6407)
File "coerce_maps.pyx", line 82, in
sage.structure.coerce_maps.DefaultConvertMap_unique._call_
(sage/structure/coerce_maps.c:3108)
File "coerce_maps.pyx", line 77, in
sage.structure.coerce_maps.DefaultConvertMap_unique._call_
(sage/structure/coerce_maps.c:3010)
File "/opt/sage-4.5.2/local/lib/python2.6/site-
packages/sage/rings/polynomial/polynomial_ring.py", line 313, in
_element_constructor_
return C(self, x, check, is_gen, construct=construct, **kwds)
File "/opt/sage-4.5.2/local/lib/python2.6/site-
packages/sage/rings/polynomial/polynomial_element_generic.py", line 656,
in __init__
x = [QQ(z) for z in x]
File "parent.pyx", line 859, in sage.structure.parent.Parent.__call__
(sage/structure/parent.c:6407)
File "coerce_maps.pyx", line 82, in
sage.structure.coerce_maps.DefaultConvertMap_unique._call_
(sage/structure/coerce_maps.c:3108)
File "coerce_maps.pyx", line 77, in
sage.structure.coerce_maps.DefaultConvertMap_unique._call_
(sage/structure/coerce_maps.c:3010)
File "rational.pyx", line 367, in sage.rings.rational.Rational.__init__
(sage/rings/rational.c:5781)
File "rational.pyx", line 521, in
sage.rings.rational.Rational.__set_value (sage/rings/rational.c:7052)
TypeError: Unable to coerce 0 (<class
'sage.algebras.free_algebra_element.FreeAlgebraElement'>) to Rational
}}}
Thanks!
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/4539#comment:31>
Sage <http://www.sagemath.org>
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