Failure in Deep-copying Matrices Over Certain Laurent-Series-Rings

[333767a0-8bb0-4499-a032-33e52572d678]

Deep-copying matrices over laurent-series-rings whose base-rings are GF(pⁿ) with large enough values of p,n, seem to fail for most matrices.

sage: import copy
sage: K = GF(41^3)
sage: S.<s> = LaurentSeriesRing(K)
sage: A = matrix(S, [(5*K.gen()^2 + 8*K.gen() + 31)*s])
sage: A
[(5*z3^2 + 8*z3 + 31)*s]
sage: C = copy.deepcopy(A)          # succeeds
sage: A = matrix(S, [(5*K.gen()^2 + 8*K.gen() + 31)*s + s^2])
sage: A
[(5*z3^2 + 8*z3 + 31)*s + s^2]
sage: C = copy.deepcopy(A)          # fails
---------------------------------------------------------------------------
...
TypeError: unable to convert PARI t_SER to finite field element

Component: linear algebra

Keywords: copy, matrix, laurent, finite_fields

Issue created by migration from https://trac.sagemath.org/ticket/30422

[mkoeppe]

comment:2

Moving this ticket to 9.4, as it seems unlikely that it will be merged in 9.3, which is in the release candidate stage