Adding argument to eigvals

[mfalt]

The ordering of roots of polynomials is changing with version Julia > 1.2.
Would you be interested in adding a keyword to roots that propagates to eigvals to change this?
In particular, I want to be able to keep the default "ordering" from LAPACK where complex-conjugates are sorted together (JuliaControl/ControlSystems.jl#236)

[jverzani]

That's a good idea! Thanks. Did you want to work out a pull request?

[mfalt]

Sure, I see two alternatives, either a simple kwargs... on definition of roots and input to eigvals, i.e. the user has to be careful about which kwargs to pass or an explicit sortby as kwarg on the root input and in the function something like:

@static if VERSION > v"1.2.0-DEV.0"
    D = eigvals(companion, sortby=sortby)
else
    D = eigvals(companion)
    if sortby !== nothing
        sort!(D, by = sortby)
    end
end

For me it doesn't really matter

[mfalt]

Since I'm doing updates anyway, what do you think of setting var=p.var as kwarg in printpoly? I.e.

printpoly(io::IO, p::Poly{T}, mimetype=MIME"text/plain"(); descending_powers=false, offset::Int=0)

to

printpoly(io::IO, p::Poly{T}, mimetype=MIME"text/plain"(); descending_powers=false, offset::Int=0, var=p.var)

This would allow us to remove most of the code in:
https://github.com/JuliaControl/ControlSystems.jl/blob/master/src/types/SisoTfTypes/polyprint.jl
which is a bit of a headache since it broke when you updated the print interface

[jverzani]

Sure, both seem good to me. Thanks

…

On Mon, Nov 4, 2019 at 5:18 PM Mattias Fält ***@***.***> wrote: Since I'm doing updates anyway, what do you think of setting var=p.var as kwarg in printpoly? I.e. printpoly(io::IO, p::Poly{T}, mimetype=MIME"text/plain"(); descending_powers=false, offset::Int=0) to printpoly(io::IO, p::Poly{T}, mimetype=MIME"text/plain"(); descending_powers=false, offset::Int=0, var=p.var) This would save some most of the code in: https://github.com/JuliaControl/ControlSystems.jl/blob/master/src/types/SisoTfTypes/polyprint.jl which is a bit of a headache since it broke when you updated the print interface — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#184?email_source=notifications&email_token=AADG6TCBQUQSGHM2YOED57DQSCNRXA5CNFSM4JI2HSC2YY3PNVWWK3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGOEDA5EYA#issuecomment-549573216>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AADG6TD3Q56HYND265QUWRLQSCNRXANCNFSM4JI2HSCQ> .

-- John Verzani Department of Mathematics College of Staten Island, CUNY verzani@math.csi.cuny.edu

[mfalt]

Feel free to close this and tag a version.