# LinearAlgebra: change in behavior between 1.1 and 1.7
**URL:** https://discourse.julialang.org/t/linearalgebra-change-in-behavior-between-1-1-and-1-7/58948
**Category:** General Usage
**Created:** [April 9, 2021, 9:50pm UTC](https://discourse.julialang.org/t/linearalgebra-change-in-behavior-between-1-1-and-1-7/58948 "2021-04-09T21:50:23Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@harven](https://discourse.julialang.org/u/harven)
#### Post date: [April 9, 2021, 9:50pm UTC](https://discourse.julialang.org/t/linearalgebra-change-in-behavior-between-1-1-and-1-7/58948/1 "2021-04-09T21:50:23Z")
The following code gives different results under 1.1 and 1.7.
```
PP = [1 0 1 0 1 0
0 1 1 0 1 0
1 0 1 0 0 1
1 0 0 1 0 1
0 1 0 1 1 0
0 1 0 1 0 1] // 3
using LinearAlgebra
eigvals(PP)
```
julia 1.1 returns a 6-element Array{Float64,1}
julia 1.7 returns a 6-element Vector{ComplexF64}
Why is it so? I spotted this change because 1.7 gives me an error further down the computation which was not there with 1.1, coming from taking the maximum of a complex-valued matrix.
```
maximum(eigvals(PP)) # 1.7
no method matching isless(::ComplexF64, ::ComplexF64)
```
---
### Author:  [@aramirezreyes](https://discourse.julialang.org/u/aramirezreyes)
#### Post date: [April 9, 2021, 10:42pm UTC](https://discourse.julialang.org/t/linearalgebra-change-in-behavior-between-1-1-and-1-7/58948/2 "2021-04-09T22:42:17Z")
I cannot reproduce on a freshly built (0 days old master) 1.7 on macOS
```julia
julia> PP = [1 0 1 0 1 0
0 1 1 0 1 0
1 0 1 0 0 1
1 0 0 1 0 1
0 1 0 1 1 0
0 1 0 1 0 1] // 3
6×6 Matrix{Rational{Int64}}:
1//3 0//1 1//3 0//1 1//3 0//1
0//1 1//3 1//3 0//1 1//3 0//1
1//3 0//1 1//3 0//1 0//1 1//3
1//3 0//1 0//1 1//3 0//1 1//3
0//1 1//3 0//1 1//3 1//3 0//1
0//1 1//3 0//1 1//3 0//1 1//3
julia> using LinearAlgebra
julia> eigvals(PP)
6-element Vector{Float64}:
-1.1102230246251565e-16
8.326672684688674e-17
0.33333333333333326
0.33333333333333326
0.33333333333333337
1.0
julia> versioninfo()
Julia Version 1.7.0-DEV.896
Commit 2f0156a6c7* (2021-04-09 22:26 UTC)
Platform Info:
OS: macOS (x86_64-apple-darwin20.3.0)
CPU: Intel(R) Core(TM) i7-8559U CPU @ 2.70GHz
WORD_SIZE: 64
LIBM: libopenlibm
LLVM: libLLVM-11.0.1 (ORCJIT, skylake)
Environment:
JULIA_EDITOR = /Applications/Emacs.app/Contents/MacOS/Emacs "$@"
```
---
### Author:  [@dodd](https://discourse.julialang.org/u/dodd)
#### Post date: [April 9, 2021, 10:53pm UTC](https://discourse.julialang.org/t/linearalgebra-change-in-behavior-between-1-1-and-1-7/58948/3 "2021-04-09T22:53:23Z")
Not 100% sure, but I think this change (returning Complex{T} eigvals for a Matrix{T\<:Real}) would have been made to improve type-stability of `eigvals`. Matrices with all-real entries can have complex eigenvalues (in conjugate pairs). The only way the compiler can safely guess the `eigvals` output type is if complex eigenvalue arrays are always returned, even if all eigenvalues have zero imaginary part. Julia code is much faster when the compiler can infer the type of data returned by a function, so I would bet this change improved the performance of `eigvals` in some cases.
---
### Author:  [@harven](https://discourse.julialang.org/u/harven)
#### Post date: [April 10, 2021, 7:19am UTC](https://discourse.julialang.org/t/linearalgebra-change-in-behavior-between-1-1-and-1-7/58948/4 "2021-04-10T07:19:36Z")
> [@aramirezreyes](#):
>
> `eigvals(PP)`
Weird. My installation is from yesterday. I am using linux, julia was compiled from source.
```
_
_ _ _(_)_ | Documentation: https://docs.julialang.org
(_) | (_) (_) |
_ _ _| |_ __ _ | Type "?" for help, "]?" for Pkg help.
| | | | | | |/ _` | |
| | |_| | | | (_| | | Version 1.7.0-DEV.894 (2021-04-09)
_/ |\ __'_|_|_|\__'_| | Commit 4996445df3* (0 days old master)
|__/ |
julia> PP = [1 0 1 0 1 0
0 1 1 0 1 0
1 0 1 0 0 1
1 0 0 1 0 1
0 1 0 1 1 0
0 1 0 1 0 1] // 3
6×6 Matrix{Rational{Int64}}:
1//3 0//1 1//3 0//1 1//3 0//1
0//1 1//3 1//3 0//1 1//3 0//1
1//3 0//1 1//3 0//1 0//1 1//3
1//3 0//1 0//1 1//3 0//1 1//3
0//1 1//3 0//1 1//3 1//3 0//1
0//1 1//3 0//1 1//3 0//1 1//3
julia> using LinearAlgebra
julia> eigvals(PP)
6-element Vector{ComplexF64}:
1.3158237332208615e-16 - 8.012357677697767e-17im
1.3158237332208615e-16 + 8.012357677697767e-17im
0.333333333333333 + 0.0im
0.33333333333333315 + 0.0im
0.3333333333333333 + 0.0im
0.9999999999999996 + 0.0im
```