fix equality of QRCompactWY #41363
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fix equality of QRCompactWY #41363
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Equality for `QRCompactWY` did not ignore the subdiagonal entries of `T` leading to nondeterministic behavior. Perhaps `T` should be directly stored as `UpperTriangular` in `QRCompactWY`, but that seems potentially breaking. This is pulled out from #41228, since this change should be less controversial than the other changes there and this particular bug just came up in ChainRules again.
simeonschaub
added
linear algebra
Seems unlikely to be breaking. |
51 tasks
stdlib/LinearAlgebra/src/qr.jl
Outdated
| @@ -127,6 +127,16 @@ Base.iterate(S::QRCompactWY) = (S.Q, Val(:R)) | |||
| Base.iterate(S::QRCompactWY, ::Val{:R}) = (S.R, Val(:done)) | |||
| Base.iterate(S::QRCompactWY, ::Val{:done}) = nothing | |||
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|
|||
| function Base.hash(F::QRCompactWY, h::UInt) | |||
| return hash(F.factors, hash(UpperTriangular(F.T), hash(QRCompactWY, h))) | |||
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This is not correct. Generally, the T matrix will not be square but wide where the number of rows is a block size, see
julia/stdlib/LinearAlgebra/src/qr.jl
Line 249 in 1e3ae23
min(size(A)...). For matrices smaller than the block size T will be square but for larger matrices, it will consist of several triangular blocks side by side, so the hashing here will be slightly more complicated and depend on the block size.
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Ah, I see! (Random appreciation for the new sparse matrix printing:
julia> using LinearAlgebra, SparseArrays
julia> a = rand(100, 100);
julia> sparse(qr(a).T .== qr(a).T)
36×100 SparseMatrixCSC{Bool, Int64} with 1767 stored entries:
⠙⢿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⠙⢿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⠙⢿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿
⠀⠀⠙⢿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⠀⠀⠙⢿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⠀⠀⠙⢿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿
⠀⠀⠀⠀⠙⢿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⠀⠀⠀⠀⠙⢿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⠀⠀⠀⠀⠙⢿⣿⣿⣿⣿⣿⣿⣿⣿
⠀⠀⠀⠀⠀⠂⠛⢿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⠀⠀⠀⠀⠀⠀⠙⢿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⠀⠀⠀⠀⠀⠀⠙⢿⣿⣿⣿⣿⣿⣿
⠀⠀⠀⠀⠀⠀⠀⠀⠙⢿⣿⣿⣿⣿⣿⣿⣿⣿⠀⠀⠀⠀⠀⠀⠀⠀⠙⢿⣿⣿⣿⣿⣿⣿⣿⣿⠀⠀⠀⠀⠀⠀⢀⠐⠙⢿⣿⣿⣿⣿
⠀⠀⠐⠀⠀⠀⠀⠀⠀⢀⢙⣿⣿⣿⣿⣿⣿⣿⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠙⢿⣿⣿⣿⣿⣿⣿⠀⠀⠀⠀⠀⠀⠁⠀⡀⠀⠙⢿⣿⣿
⠀⠀⠐⠀⠀⠀⠀⠀⠀⠀⠄⠀⠙⢿⣿⣿⣿⣿⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠙⢿⣿⣿⣿⣿⠀⠀⠀⠀⠀⠀⡀⠀⠀⢀⠀⠀⠙⢿
⠀⡀⠀⠀⠀⠀⠀⠀⠂⠒⠒⠀⠀⠀⠙⢿⣿⣿⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠙⢿⣿⣿⠀⠀⠀⠀⠀⠀⠀⢀⠀⠀⠀⡀⠀⠀
⠀⠀⠀⠀⠀⠀⠀⠀⣈⡀⠀⠀⠀⠀⠀⠀⠙⢿⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠙⢿⠀⠀⠀⠀⠀⠀⠀⠀⠀⡀⠂⠀⢀⠀)
|
@oxinabox See Andreas' comment. I was misinformed, unfortunately just making |
andreasnoack
approved these changes
Jun 28, 2021
simeonschaub
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Jun 28, 2021
Equality for `QRCompactWY` did not ignore the subdiagonal entries of `T` leading to nondeterministic behavior. This is pulled out from #41228, since this change should be less controversial than the other changes there and this particular bug just came up in ChainRules again.
KristofferC
pushed a commit
that referenced
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Jun 29, 2021
* fix equality of QRCompactWY (#41363) Equality for `QRCompactWY` did not ignore the subdiagonal entries of `T` leading to nondeterministic behavior. This is pulled out from #41228, since this change should be less controversial than the other changes there and this particular bug just came up in ChainRules again.
45 tasks
KristofferC
pushed a commit
that referenced
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Jun 30, 2021
Equality for `QRCompactWY` did not ignore the subdiagonal entries of `T` leading to nondeterministic behavior. This is pulled out from #41228, since this change should be less controversial than the other changes there and this particular bug just came up in ChainRules again. (cherry picked from commit 74fab49)
johanmon
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Jul 5, 2021
Equality for `QRCompactWY` did not ignore the subdiagonal entries of `T` leading to nondeterministic behavior. This is pulled out from JuliaLang#41228, since this change should be less controversial than the other changes there and this particular bug just came up in ChainRules again.
staticfloat
pushed a commit
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Dec 23, 2022
* fix equality of QRCompactWY (#41363) Equality for `QRCompactWY` did not ignore the subdiagonal entries of `T` leading to nondeterministic behavior. This is pulled out from #41228, since this change should be less controversial than the other changes there and this particular bug just came up in ChainRules again.
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Equality for
QRCompactWYdid not ignore the subdiagonal entries ofTleading to nondeterministic behavior. PerhapsTshould bedirectly stored as
UpperTriangularinQRCompactWY, but that seemspotentially breaking.
This is pulled out from #41228, since this change should be less
controversial than the other changes there and this particular bug just
came up in ChainRules again.