Conversions to and from RationalFunction broken about polynomials.jl

[jverzani]

Thanks for letting me know!

[jishnub]

Note that there are other instances like

Polynomials.jl/src/rational-functions/common.jl

Lines 52 to 64 in 263b965

	function Base.convert(::Type{PQ}, q::LaurentPolynomial) where {PQ <: AbstractRationalFunction}
	m = firstindex(q)
	if m >= 0
	p = convert(Polynomial, q)
	return convert(PQ, p)
	else
	z = variable(q)
	zᵐ = z^(-m)
	p = convert(Polynomial, zᵐ * q)
	return rational_function(PQ, p, convert(Polynomial, zᵐ))
	end
	end

where the convert explicitly uses Polynomial, which may not be the correct type

[jverzani]

Yes, that one was deliberate. Perhaps it should just be deprecated and the user should convert to a polynomial type without negative powers before using.

Thanks again! I really appreciate your time and effort to point these out.