StackOverflowError on an utils function

[zhanglw0521]

In utils.jl, we have the following

function specnlm2spec1p(spec_nlm)
    spec1p = union(spec_nlm...)
    lmax = [ spec1p[i].l for i = 1:length(spec1p) ] |> maximum
    nmax = [ spec1p[i].n for i = 1:length(spec1p) ] |> maximum
    return spec1p, lmax, nmax + 1
end

which extracts the corresponding Aspec from an input AAspec (I actually don't remember why we need lmax and nmax in the output but let's keep it for now).

However the union function in the first line seems to give a StackOverflowError. For instance, when we run

Zi = :C
Zs = [:H,:C,:O]

cats_ext = [(Zi,Z) for Z in Zs] |> unique

maxdeg = 6
ord = 3
radial = simple_radial_basis(legendre_basis(maxdeg))
Lmax = 0

Aspec, AAspec = degord2spec(radial; totaldegree = maxdeg, 
                                  order = ord, 
                                  Lmax = Lmax, catagories = cats_ext)

this issue arises.

It can be fixed by something like

function specnlm2spec1p(spec_nlm)
    spec1p = []
    for (i, spec_nlm_i) in enumerate(spec_nlm)
        push!(spec1p, spec_nlm_i...)
        unique!(spec1p)
    end
    lmax = [ spec1p[i].l for i = 1:length(spec1p) ] |> maximum
    nmax = [ spec1p[i].n for i = 1:length(spec1p) ] |> maximum
    return spec1p, lmax, nmax + 1
end

A PR regarding this issue will follow soon.

[zhanglw0521]

resolved by #29