# LinearAlgebra.eigen does not accept adjoint matrices ?
**URL:** https://discourse.julialang.org/t/linearalgebra-eigen-does-not-accept-adjoint-matrices/13410
**Category:** General Usage
**Created:** [August 13, 2018, 10:02pm UTC](https://discourse.julialang.org/t/linearalgebra-eigen-does-not-accept-adjoint-matrices/13410 "2018-08-13T22:02:51Z")
**Posts on this page:** 10
**Page:** 1
### Author:  [@kragol](https://discourse.julialang.org/u/kragol)
#### Post date: [August 13, 2018, 10:02pm UTC](https://discourse.julialang.org/t/linearalgebra-eigen-does-not-accept-adjoint-matrices/13410/1 "2018-08-13T22:02:51Z")
Since julia 0.7, the following code
```julia
using LinearAlgebra
A = randn(10,10)
E = eigen(A')
```
returns an error
```julia
ERROR: MethodError: no method matching eigen(::Adjoint{Float64,Array{Float64,2}})
```
This looks like a bug to me but maybe this is by design ?
If so, is there a smarter workaround than using the Matrix function ? As in
```julia
E = eigen(Matrix(A'))
```
which is quite unnatural in my opinion. It looks like it may also ruin any possible optimization for special matrices, (e.g. Sparse, Diagonal, Bidiagonal, etc).
---
### Author:  [@tkoolen](https://discourse.julialang.org/u/tkoolen)
#### Post date: [August 13, 2018, 10:06pm UTC](https://discourse.julialang.org/t/linearalgebra-eigen-does-not-accept-adjoint-matrices/13410/2 "2018-08-13T22:06:18Z")
Re: special matrices: you can use `copy`:
```julia
julia> using LinearAlgebra
julia> Matrix(Diagonal([1, 2])')
2×2 Array{Int64,2}:
1 0
0 2
julia> copy(Diagonal([1, 2])')
2×2 Diagonal{Int64,Array{Int64,1}}:
1 ⋅
⋅ 2
```
---
### Author:  [@DNF](https://discourse.julialang.org/u/DNF)
#### Post date: [August 13, 2018, 10:32pm UTC](https://discourse.julialang.org/t/linearalgebra-eigen-does-not-accept-adjoint-matrices/13410/3 "2018-08-13T22:32:03Z")
But shouldn’t it fall back on some method for `AbstractArray`?
---
### Author:  [@tkoolen](https://discourse.julialang.org/u/tkoolen)
#### Post date: [August 13, 2018, 10:33pm UTC](https://discourse.julialang.org/t/linearalgebra-eigen-does-not-accept-adjoint-matrices/13410/4 "2018-08-13T22:33:25Z")
Yes, probably.
---
### Author:  [@kragol](https://discourse.julialang.org/u/kragol)
#### Post date: [August 14, 2018, 12:59am UTC](https://discourse.julialang.org/t/linearalgebra-eigen-does-not-accept-adjoint-matrices/13410/5 "2018-08-14T00:59:51Z")
Thanks. That seems to sort out the optimzation issue.
Not really the ugliness though…
---
### Author:  [@kragol](https://discourse.julialang.org/u/kragol)
#### Post date: [August 14, 2018, 12:59am UTC](https://discourse.julialang.org/t/linearalgebra-eigen-does-not-accept-adjoint-matrices/13410/6 "2018-08-14T00:59:56Z")
Duplicate. (my reply was stuck in new user limbo)
---
### Author:  [@tkoolen](https://discourse.julialang.org/u/tkoolen)
#### Post date: [August 14, 2018, 1:11pm UTC](https://discourse.julialang.org/t/linearalgebra-eigen-does-not-accept-adjoint-matrices/13410/7 "2018-08-14T13:11:41Z")
What do you think the implementation should be? Maybe indeed just
```julia
LinearAlgebra.eigen(x::Union{Transpose{T, A}, Adjoint{T, A}}) where {T, A<:AbstractMatrix} = eigen(copy(x))
```
You could add some tests and submit a PR to JuliaLang/julia.
---
### Author:  [@kragol](https://discourse.julialang.org/u/kragol)
#### Post date: [August 16, 2018, 12:24pm UTC](https://discourse.julialang.org/t/linearalgebra-eigen-does-not-accept-adjoint-matrices/13410/8 "2018-08-16T12:24:27Z")
I’d be happy to do it but I am a newcomer to julia and I am not sure how to do these things properly. I will have a look at the `eigen.jl` test file and see if I can write something not too stupid.
In the meantime I can open an issue referencing your code suggestion. It may be a good idea anyway as I would not be surprised if Adjoint types broke some other LinearAlgebra functions.
---
### Author:  [@tkoolen](https://discourse.julialang.org/u/tkoolen)
#### Post date: [August 16, 2018, 1:55pm UTC](https://discourse.julialang.org/t/linearalgebra-eigen-does-not-accept-adjoint-matrices/13410/9 "2018-08-16T13:55:33Z")
Sounds good. For context, `transpose` and `adjoint` have only recently become lazy (the `Adjoint` and `Transpose` types are new in 0.7), which is why there might still be a few missing methods for these types.
---
### Author:  [@kragol](https://discourse.julialang.org/u/kragol)
#### Post date: [August 16, 2018, 11:14pm UTC](https://discourse.julialang.org/t/linearalgebra-eigen-does-not-accept-adjoint-matrices/13410/10 "2018-08-16T23:14:29Z")
I have submitted [Issue #28714](https://github.com/JuliaLang/julia/issues/28714) on this topic.