roots of constant polynomial

[laurentbartholdi]

I'm having serious trouble with roots for QQBarFieldElem:

julia> R,z = QQBarField()[:z]
(Univariate polynomial ring in z over QQBar, z)

julia> roots(z^2) # the documentation says that it would return two copies of the root 0
1-element Vector{QQBarFieldElem}:
 Root 0 of x

julia> roots(z^0) # ka-boom, should return the empty list
ERROR: DivideError: integer division error

Note: the rest of this issue was moved into a separate issue #2119

[fingolfin]

Just a small side remark: It would be more helpful for us if you filed one issue per issue, instead of describing multiple issues in one issue ;-)

[fieker]

The documentation of root(f) promises not a lot:

roots(f::PolyRingElem)

Returns the roots of the polynomial f in the base ring of f as an array.

The docu of roots(Field, Poly) in general also does not promise more, only:
Only roots(QQBarField, ZZPolyRingElem) and QQPolyRingElem promise the multiplicity - don't know if this makes it any better...

Roots with multiplicitiy should be discussed and implemented (or not) in a seperate track.

[fieker]

x^0 is fixed in thofma/Hecke.jl#1905

[fingolfin]

I already made a separate issue for the multiplicity business, see #2119