Clarify the role of pivoting in QR factorization #29976
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andreasnoack
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Nov 9, 2018
andreasnoack
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Nov 9, 2018
stdlib/LinearAlgebra/src/qr.jl
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| @@ -318,7 +318,9 @@ Iterating the decomposition produces the components `Q`, `R`, and if extant `p`. | |||
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| The following functions are available for the `QR` objects: [`inv`](@ref), [`size`](@ref), | |||
| and [`\\`](@ref). When `A` is rectangular, `\\` will return a least squares | |||
| solution and if the solution is not unique, the one with smallest norm is returned. | |||
| solution and if the solution is not unique, the one with smallest norm is returned. When | |||
| `A` is not full rank, factorization with (column) pivoting is required to obtain a finite | |||
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I'm not sure about the "finite norm solution" part here. I'd expect it to be a "unique solution" or "minimum norm solution".
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You are right. After I submitted it, I also thought it was badly formulated. I will change it when I get home.
kshyatt
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You mean backporting to the docs of v1.0.1? If so and you don't mind, I can do that. |
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@mzaffalon You don't have to do anything here. I believe the process is mostly automated at this point once an issue has been marked for backporting. |
KristofferC
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Nov 28, 2018
* Clarify the role of pivoting in QR factorization Ref: https://discourse.julialang.org/t/left-matrix-division-with-singular-matrix/15503 * Update qr.jl (cherry picked from commit e5e6b64)
KristofferC
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Dec 12, 2018
* Clarify the role of pivoting in QR factorization Ref: https://discourse.julialang.org/t/left-matrix-division-with-singular-matrix/15503 * Update qr.jl (cherry picked from commit e5e6b64)
KristofferC
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Feb 11, 2019
* Clarify the role of pivoting in QR factorization Ref: https://discourse.julialang.org/t/left-matrix-division-with-singular-matrix/15503 * Update qr.jl (cherry picked from commit e5e6b64)
KristofferC
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Feb 20, 2020
* Clarify the role of pivoting in QR factorization Ref: https://discourse.julialang.org/t/left-matrix-division-with-singular-matrix/15503 * Update qr.jl (cherry picked from commit e5e6b64)
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Ref: https://discourse.julialang.org/t/left-matrix-division-with-singular-matrix/15503