lufact for sparse matrix pivot option error #18246
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base/sparse/umfpack.jl includes the following method definition for lufact
`lufact(A::SparseMatrixCSC, pivot::Type{Val{false}}) = lufact(A)`
This should likely be
`lufact(A::SparseMatrixCSC, pivot::Type{Val{true}}) = lufact(A)`
because in lufact pivoting is on by default.
The error is shown in the following example
```
A = speye(4)
A[1:2,1:2] = [-.01 -200; 200 .001]
F = lufact(A,Val{false})
F[:p]
```
which returns
```
julia> F[:q]
4-element Array{Int64,1}:
3
4
1
2
```
However it should return
```
julia> F[:q]
4-element Array{Int64,1}:
1
2
3
4
```
because pivoting was turned off.
lufact for sparse matrix pivot option error
|
Thanks. That method is indeed wrong. I'm wondering why we have it. @jiahao Do you remember why you added it? |
|
I don't recall... Ref: #18244 @garrettthomaskth Could you help us add the nice test case you show as a test in |
| #18246,18244-lufact sparse pivot | ||
| let | ||
| A = speye(4) |
There was a problem hiding this comment.
oops. okay added the 4 space indent
oops my bad
|
@garrettthomaskth Could you try just to remove the method and see what happens? Since we don't support turning off pivoting I don't think this method is necessary. |
|
Great. Thanks. |
|
why should deleting a method be backported? |
|
The method was wrong. It pretended to disable pivoting but didn't. |
mfasi
pushed a commit
to mfasi/julia
that referenced
this pull request
Sep 5, 2016
* lufact for sparse matrix pivot option error
base/sparse/umfpack.jl includes the following method definition for lufact
`lufact(A::SparseMatrixCSC, pivot::Type{Val{false}}) = lufact(A)`
This should likely be
`lufact(A::SparseMatrixCSC, pivot::Type{Val{true}}) = lufact(A)`
because in lufact pivoting is on by default.
The error is shown in the following example
```
A = speye(4)
A[1:2,1:2] = [-.01 -200; 200 .001]
F = lufact(A,Val{false})
F[:p]
```
which returns
```
julia> F[:q]
4-element Array{Int64,1}:
3
4
1
2
```
However it should return
```
julia> F[:q]
4-element Array{Int64,1}:
1
2
3
4
```
because pivoting was turned off.
* Added test for JuliaLang#18246 and JuliaLang#18244
* 4 space indent
oops my bad
* remove unnecessary lufact method
* update test for removed lufact method definition
tkelman
pushed a commit
that referenced
this pull request
Feb 22, 2017
* lufact for sparse matrix pivot option error
base/sparse/umfpack.jl includes the following method definition for lufact
`lufact(A::SparseMatrixCSC, pivot::Type{Val{false}}) = lufact(A)`
This should likely be
`lufact(A::SparseMatrixCSC, pivot::Type{Val{true}}) = lufact(A)`
because in lufact pivoting is on by default.
The error is shown in the following example
```
A = speye(4)
A[1:2,1:2] = [-.01 -200; 200 .001]
F = lufact(A,Val{false})
F[:p]
```
which returns
```
julia> F[:q]
4-element Array{Int64,1}:
3
4
1
2
```
However it should return
```
julia> F[:q]
4-element Array{Int64,1}:
1
2
3
4
```
because pivoting was turned off.
* Added test for #18246 and #18244
* 4 space indent
oops my bad
* remove unnecessary lufact method
* update test for removed lufact method definition
(cherry picked from commit 68d3d32)
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base/sparse/umfpack.jl includes the following method definition for lufact
lufact(A::SparseMatrixCSC, pivot::Type{Val{false}}) = lufact(A)which should be
lufact(A::SparseMatrixCSC, pivot::Type{Val{true}}) = lufact(A)because in lufact pivoting is on by default.
The error is shown in the following example
which returns
However it should return
because pivoting was turned off.