#13672: resultant over GF(q)[t][x] is plain wrong!!!
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Reporter: zimmerma | Owner: malb
Type: defect | Status: new
Priority: blocker | Milestone: sage-5.5
Component: commutative algebra | Resolution:
Keywords: | Work issues:
Report Upstream: N/A | Reviewers:
Authors: | Merged in:
Dependencies: | Stopgaps:
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Comment (by zimmerma):
with the modified {{{check}}} routine below:
{{{
def check(df,dg,S):
f = S.random_element(degree=df)
while f.degree() < df:
f = S.random_element(degree=df)
g = S.random_element(degree=dg)
while g.degree() < dg:
g = S.random_element(degree=dg)
r1 = f.resultant(g)
r2 = Resultant(f,g)
return r1 == r2
def foo(df,dg,F,K):
R.<t> = F[]
S.<x> = R[]
err = 0
for k in range(K):
if check(df,dg,S) == False:
err += 1
return err
}}}
then {{{foo(1,1,GF(2),1000)}}} gives 788 failures out of 1000 tries, with
GF(3) I get 969
errors out of 1000, with GF(11) 1000 errors. Thus all finite fields are
concerned.
Paul
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Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/13672#comment:2>
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