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Groups.jl
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convenience constructors for DirectProduct

This commit is contained in:
kalmarek 2018-07-30 14:56:28 +02:00
parent 8a40d76143
commit 0de75f1262
1 changed files with 9 additions and 1 deletions
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10
src/DirectProducts.jl
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@ -142,6 +142,14 @@ function ×(G::Group, H::Group)
return DirectProductGroup(G,2)
end
×(H::Group, G::DirectProductGroup) = G×H
function ×(G::DirectProductGroup, H::Group)
G.group == H || throw(DomainError(
"Direct products are defined only for the same groups"))
return DirectProductGroup(G.group,G.n+1)
end
DirectProductGroup(R::T, n::Int) where {T<:AbstractAlgebra.Ring} =
DirectProductGroup(AdditiveGroup(R), n)
@ -174,7 +182,7 @@ end
(G::DirectProductGroup)(g::DirectProductGroupElem) = G(g.elts)
(G::DirectProductGroup){T<:GroupElem, N}(a::Vararg{T, N}) = G([a...])
(G::DirectProductGroup)(a::Vararg{T, N}) where {T, N} = G([a...])
###############################################################################
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