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openedon Oct 16, 2020
julia> A = [1 2; 3 4];
julia> AH = Symmetric(A);
julia> AH .+= Diagonal(A)
ERROR: ArgumentError: Cannot set a non-diagonal index in a symmetric matrix
Stacktrace:
[1] setindex!
@ /usr/local/src/julia/julia-master/usr/share/julia/stdlib/v1.6/LinearAlgebra/src/symmetric.jl
:225 [inlined]
[2] _setindex!
@ ./abstractarray.jl:1247 [inlined]
[3] setindex!
@ ./abstractarray.jl:1217 [inlined]
[4] macro expansion
@ ./broadcast.jl:932 [inlined]
[5] macro expansion
@ ./simdloop.jl:77 [inlined]
[6] copyto!
@ ./broadcast.jl:931 [inlined]
[7] copyto!
@ ./broadcast.jl:886 [inlined]
[8] materialize!
@ ./broadcast.jl:848 [inlined]
[9] materialize!(dest::Symmetric{Int64, Matrix{Int64}}, bc::Base.Broadcast.Broadcasted{LinearAlgebra.StructuredMatrixStyle{Diagonal{Int64, Vector{Int64}}}, Nothing, typeof(+), Tuple{Symmetric{Int64, Matrix{Int64}}, Diagonal{Int64, Vector{Int64}}}})
@ Base.Broadcast ./broadcast.jl:845
[10] top-level scope
@ REPL[17]:1Same happens to Hermian
I can do it it I am not broadcasting,
but it alocates a new AH and just rebinds the name.
Which is allocating.
julia> objectid(AH)
0x4b328c6c806ac9c2
julia> AH += Diagonal(A)
2×2 Symmetric{Int64, Matrix{Int64}}:
4 2
2 8
julia> objectid(AH)
0x67c658733e89b4a9
In contast UpperTrianguar is fine with this:
julia> AU = UpperTriangular(A)
2×2 UpperTriangular{Int64, Matrix{Int64}}:
2 2
⋅ 4
julia> AU .+= Diagonal(A)
2×2 UpperTriangular{Int64, Matrix{Int64}}:
4 2
⋅ 8I can hack around it via:
julia> parent(AH) .+= Diagonal(A);
julia> AH
2×2 Symmetric{Int64, Matrix{Int64}}:
8 2
2 16
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