LU Decomposition - return permutation matrix instead of vector

[Tamas_Papp]

I wonder if you read the docs of lu, since you can get it directly as a property:

julia> lu(A).P
3×3 Array{Float64,2}:
 0.0  1.0  0.0
 1.0  0.0  0.0
 0.0  0.0  1.0