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Fix remove_svd_gauge_dependence! for rank-deficient SVDs #286

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Merged
lkdvos merged 3 commits into from
Oct 1, 2026
Merged

Fix remove_svd_gauge_dependence! for rank-deficient SVDs #286

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98530ef
Fix `remove_svd_gauge_dependence!` for rank-deficient SVDs
leburgel Sep 30, 2026
73c4666
Update src/pullbacks/svd.jl
leburgel Sep 30, 2026
5afca7c
Also replace two remaining `@view`s
leburgel Oct 1, 2026
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6 changes: 3 additions & 3 deletions src/pullbacks/svd.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -342,11 +342,11 @@ function remove_svd_gauge_dependence!(
Sdiag = diagview(S)
gaugepart = mul!(U₁' * ΔU₁, Vᴴ₁, ΔVᴴ₁', true, true)
gaugepart = project_antihermitian!(gaugepart)
gaugepart[abs.(transpose(Sdiag) .- Sdiag) .>= degeneracy_atol] .= 0
gaugepart[abs.(transpose(view(Sdiag, 1:r)) .- view(Sdiag, 1:r)) .>= degeneracy_atol] .= 0

@Jutho Jutho Oct 1, 2026

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We could have had an S₁ = view(Sdiag, 1:r) definition and use this here, but it's fine like this.

mul!(ΔU₁, U₁, gaugepart, -1, 1)
if size(ΔU, 2) > r
if r < length(Sdiag) # rank-deficient case, no stable information can be extracted from extra columns of U
zero!(ΔU[:, (r + 1):end])
zero!(view(ΔU, :, (r + 1):size(ΔU, 2)))

@Jutho Jutho Oct 1, 2026

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This was quite stupid indeed 😄 .

else # the component of ΔU₂ along U₁ contains gauge-invariant information
p = size(ΔU, 2)
ΔU₂ = view(ΔU, :, (r + 1):p)
Expand All @@ -356,7 +356,7 @@ function remove_svd_gauge_dependence!(
end
if size(ΔVᴴ, 1) > r
if r < length(Sdiag) # rank-deficient case, no stable information can be extracted from extra rows of Vᴴ
zero!(ΔVᴴ[(r + 1):end, :])
zero!(view(ΔVᴴ, (r + 1):size(ΔVᴴ, 1), :))
else # the component of ΔVᴴ₂ along Vᴴ₁ contains gauge-invariant information
p = size(ΔVᴴ, 1)
ΔVᴴ₂ = view(ΔVᴴ, (r + 1):p, :)
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