#12240: Multivariate powerseries with symbolic coefficients issues
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Reporter: vbraun | Owner: malb
Type: defect | Status: new
Priority: major | Milestone: sage-4.8
Component: commutative algebra | Keywords: multivariate power series
Work_issues: | Upstream: N/A
Reviewer: | Author:
Merged: | Dependencies:
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Multivariate powerseries over SR seem to work, but coercion does not. For
example, the coercion from ZZ to QQ works fine:
{{{
sage: T.<a,b> = PowerSeriesRing(ZZ,2)
sage: f = 1 + a + b + a*b + T.O(5)
sage: 1/2 * f
1/2 + 1/2*a + 1/2*b + 1/2*a*b + O(a, b)^5
}}}
but the same thing fails with SR:
{{{
sage: exp(2) * f
---------------------------------------------------------------------------
TypeError Traceback (most recent call
last)
/home/vbraun/opt/sage-4.8.alpha4/devel/sage-
main/sage/schemes/generic/<ipython console> in <module>()
/home/vbraun/opt/sage-4.8.alpha4/local/lib/python2.6/site-
packages/sage/structure/element.so in
sage.structure.element.RingElement.__mul__
(sage/structure/element.c:12158)()
/home/vbraun/opt/sage-4.8.alpha4/local/lib/python2.6/site-
packages/sage/structure/coerce.so in
sage.structure.coerce.CoercionModel_cache_maps.bin_op
(sage/structure/coerce.c:7467)()
TypeError: unsupported operand parent(s) for '*': 'Symbolic Ring' and
'Multivariate Power Series Ring in a, b over Integer Ring'
}}}
Also, manually changing the base ring brings out the background polynomial
variable:
{{{
sage: f.change_ring(SR)
(Tbg*a*b + a + b)*Tbg + 1 + O(a, b)^5
}}}
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12240>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
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