Enh/dixon

[kalmarek]

there is a lot of stuff here, but we need to wait for the recent versions of Cyclotomics and PermutationGroups anyway

TLDR:

julia> using SymbolicWedderburn

julia> using PermutationGroups

julia> G = PermGroup([perm"(1,2,3)(4)", perm"(2,3,4)"])
Permutation group on 2 generators
⟨(1,2,3), (2,3,4)⟩


julia> SymbolicWedderburn.characters_dixon(G)
4-element Array{SymbolicWedderburn.Character{Cyclotomics.Cyclotomic{Int64,SparseArrays.SparseVector{Int64,Int64}},PermutationGroups.Orbit1{Perm{Int64},Nothing}},1}:
 Character: [3, 0, 0, -1]
 Character: [1,  ζ₃,  ζ₃², 1]
 Character: [1,  ζ₃²,  ζ₃, 1]
 Character: [1, 1, 1, 1]

julia> G = PermGroup([perm"(1,2,3,4)", perm"(3,4)"])
Permutation group on 2 generators
⟨(1,2,3,4), (3,4)⟩


julia> SymbolicWedderburn.characters_dixon(G)
5-element Array{SymbolicWedderburn.Character{Cyclotomics.Cyclotomic{Int64,SparseArrays.SparseVector{Int64,Int64}},PermutationGroups.Orbit1{Perm{Int64},Nothing}},1}:
 Character: [3, -1, 0, 1, -1]
 Character: [3, 1, 0, -1, -1]
 Character: [1, 1, 1, 1, 1]
 Character: [1, -1, 1, -1, 1]
 Character: [2, 0, -1, 0, 2]

[tweisser]

Great work!

[kalmarek]

are we attached to julia versions <1.3 ? these do not allow attaching methods to abstract types and we need the following (rather ugly):

if VERSION >= v"1.3.0"
    function (χ::AbstractClassFunction)(g::PermutationGroups.AbstractPerm)
        for (i, cc) in enumerate(conjugacy_classes(χ))
            g ∈ cc && return χ[i]
        end
        throw(DomainError(g, "element does not belong to conjugacy classes of χ"))
    end
else
    function (χ::Character)(g::PermutationGroups.AbstractPerm)
        for (i, cc) in enumerate(conjugacy_classes(χ))
            g ∈ cc && return χ[i]
        end
        throw(DomainError(g, "element does not belong to conjugacy classes of χ"))
    end
end

[codecov]

Codecov Report

Merging #9 into master will increase coverage by 8.80%.
The diff coverage is 77.09%.

@@            Coverage Diff             @@
##           master       #9      +/-   ##
==========================================
+ Coverage   77.72%   86.52%   +8.80%     
==========================================
  Files           6        7       +1     
  Lines         202      282      +80     
==========================================
+ Hits          157      244      +87     
+ Misses         45       38       -7     

Flag	Coverage Δ
#unittests	86.52% <77.09%> (+8.80%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
src/SymbolicWedderburn.jl	100.00% <ø> (ø)
src/characters.jl	51.78% <40.90%> (+51.78%)	⬆️
src/eigenspacedecomposition.jl	93.40% <50.00%> (-1.04%)	⬇️
src/gf.jl	93.33% <96.55%> (+1.66%)	⬆️
src/dixon.jl	97.82% <97.56%> (-2.18%)	⬇️
src/ccmatrix.jl	100.00% <100.00%> (ø)
src/powermap.jl	100.00% <100.00%> (ø)

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[kalmarek]

looks good to me ;-)