#8997: riemann_roch_basis is implemented incorrectly in sage
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Reporter: was | Owner: AlexGhitza
Type: defect | Status: new
Priority: major | Milestone: sage-5.0
Component: algebra | Keywords:
Author: | Upstream: N/A
Reviewer: | Merged:
Work_issues: |
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See the file schemes/plane_curves/projective_curve.py, where it says
{{{
The following example illustrates that the Riemann-Roch space
function in Singular doesn't *not* work correctly.
::
sage: R.<x,y,z> = GF(5)[]
sage: f = x^7 + y^7 + z^7
sage: C = Curve(f); pts = C.rational_points()
sage: D = C.divisor([ (3, pts[0]), (-1,pts[1]), (10, pts[5])
])
sage: C.riemann_roch_basis(D) # output is random (!!!!)
[x/(y + x), (z + y)/(y + x)]
The answer has dimension 2 (confirmed via Magma). But it varies
between 1 and quite large with Singular.
}}}
The problem can be solved by learning how the relevant code in Singular
works then correctly wrapping it.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/8997>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
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