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log for dense diagonal matrix with negative elements #1352

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Merged
merged 3 commits into from
May 16, 2025
Merged

log for dense diagonal matrix with negative elements #1352

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6f8f6e8
log for dense diagonal matrix with negative elements
jishnub May 12, 2025
6852f3f
Check equality with zero
jishnub May 12, 2025
a9ac43f
Test for zero element
jishnub May 12, 2025
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8 changes: 6 additions & 2 deletions src/dense.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -914,8 +914,12 @@ julia> log(A)
"""
function log(A::AbstractMatrix)
# If possible, use diagonalization
if isdiag(A)
return applydiagonal(log, A)
if isdiag(A) && eltype(A) <: Union{Real,Complex}
if eltype(A) <: Real && all(>=(0), diagview(A))
return applydiagonal(log, A)
else
return applydiagonal(log∘complex, A)
end
elseif ishermitian(A)
logHermA = log(Hermitian(A))
PH = parent(logHermA)
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11 changes: 11 additions & 0 deletions test/dense.jl
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Expand Up @@ -1418,4 +1418,15 @@ end
@test tril(GenericArray(M),-1) == res'
end

@testset "log for diagonal" begin
D = diagm([-2.0, 2.0])
@test log(D) ≈ log(UpperTriangular(D))
D = diagm([-2.0, 0.0])
@test log(D) ≈ log(UpperTriangular(D))
D = diagm([2.0, 2.0])
@test log(D) ≈ log(UpperTriangular(D))
D = diagm([2.0, 2.0*im])
@test log(D) ≈ log(UpperTriangular(D))
end

end # module TestDense