id summary reporter owner description type status priority milestone component resolution keywords cc merged author reviewer upstream work_issues branch commit dependencies stopgaps
24900 Tensor product and coefficients Florent Hivert "Tensor products of combinatorial free modules still use an old version of
cartesian product. As a consequence extracting a coefficient is not possible:
{{{
sage: F = CombinatorialFreeModule(ZZ, [1,2]); F.__custom_name = ""F""
sage: G = CombinatorialFreeModule(ZZ, [3,4]); G.__custom_name = ""G""
sage: T = tensor([F, G]); T
sage: T.basis()[(1,3)].coefficient((1,3))
...
NotImplementedError:
}}}
I fix that. As a side effect, this change the result of {{{an_element}}} so that I
have to fix a few doctests.
Moreover, building the tensor of two infinite dimensional FM now raises a correct
warning:
{{{
sage: F = CombinatorialFreeModule(ZZ, NN)
sage: T = tensor([F, F]); T
Free module generated by Non negative integer semiring over Integer Ring ⊗ Free module generated by Non negative integer semiring over Integer Ring
sage: T.an_element()
/home/data/Sage-Install/sage-dev/local/lib/python2.7/site-packages/sage/categories/sets_cat.py:2159: UserWarning: Sage is not able to determine whether the factors of this Cartesian product are finite. The lexicographic ordering might not go through all elements.
warn(""Sage is not able to determine whether the factors of ""
2*B[0] ⊗ B[1] + B[0] ⊗ B[0] + 3*B[0] ⊗ B[2] + B[42] ⊗ B[42]
}}}
I'm hiding this by asking only finite dim FM.
" defect needs_work major sage-9.8 linear algebra tensor product, free modules Nicolas M. Thiéry Travis Scrimshaw Matthias Köppe Florent Hivert N/A public/cartesian_24900 bfa36e785be6af5bb7031d785c8469acfcd1472b #19195