# Issue Arpack computing eigs

**URL:** <https://discourse.julialang.org/t/issue-arpack-computing-eigs/93254>\
**Category:** General Usage\
**Tags:** question, package\
**Created:** [January 20, 2023, 9:40am UTC](https://discourse.julialang.org/t/issue-arpack-computing-eigs/93254 "2023-01-20T09:40:11Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Sparsetacus](https://avatars.discourse-cdn.com/v4/letter/s/ac8455/32.png) [@Sparsetacus](https://discourse.julialang.org/u/Sparsetacus)\
**Post date:** [January 20, 2023, 9:40am UTC](https://discourse.julialang.org/t/issue-arpack-computing-eigs/93254/1 "2023-01-20T09:40:11Z")

</div>

Hi all,  
I have a weird error using Arpack.jl.  
I am using eigs to compute a generalized eigenvalue problem for large, symmetric, sparse matrices, i.e. `eigs(A, B, nev = 1, which = :SM)`.  
I am using julia 1.8.5 on ubuntu 22.04 and while the computation works perfectly fine on my laptop, I have an error on my desktop for the exact same code.

The error I have :

```julia
ERROR: LoadError: ┌ Error: XYAUPD_Exception: Maximum number of iterations taken. All possible eigenvalues of OP has been found.
│ IPARAM(5) returns the number of wanted converged Ritz values.
│ info = 1
└ @ Arpack ~/.julia/packages/Arpack/FCvNd/src/libarpack.jl:47

Stacktrace:
 [1] aupd_wrapper(T::Type, matvecA!::Arpack.var"#12#22"{LinearAlgebra.Symmetric{Float64, SparseArrays.SparseMatrixCSC{Float64, Int64}}}, matvecB::Arpack.var"#19#29"{LinearAlgebra.Symmetric{Float64, SparseArrays.SparseMatrixCSC{Float64, Int64}}}, solveSI::Arpack.var"#20#30", n::Int64, sym::Bool, cmplx::Bool, bmat::String, nev::Int64, ncv::Int64, which::String, tol::Float64, maxiter::Int64, mode::Int64, v0::Vector{Float64}, check::Int64)
   @ Arpack ~/.julia/packages/Arpack/FCvNd/src/libarpack.jl:141
 [2] _eigs(A::LinearAlgebra.Symmetric{Float64, SparseArrays.SparseMatrixCSC{Float64, Int64}}, B::LinearAlgebra.Symmetric{Float64, SparseArrays.SparseMatrixCSC{Float64, Int64}}; nev::Int64, ncv::Int64, which::Symbol, tol::Float64, maxiter::Int64, sigma::Nothing, v0::Vector{Float64}, ritzvec::Bool, explicittransform::Symbol, check::Int64)
   @ Arpack ~/.julia/packages/Arpack/FCvNd/src/Arpack.jl:240
 [3] #eigs#5
   @ ~/.julia/packages/Arpack/FCvNd/src/Arpack.jl:53 [inlined]

```

I entirely reinstalled julia on my desktop and the error still appear.

Any idea where this could come from ?

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<div class="post-metadata">

**Author:** ![Sparsetacus](https://avatars.discourse-cdn.com/v4/letter/s/ac8455/32.png) [@Sparsetacus](https://discourse.julialang.org/u/Sparsetacus)\
**Post date:** [January 25, 2023, 1:31pm UTC](https://discourse.julialang.org/t/issue-arpack-computing-eigs/93254/2 "2023-01-25T13:31:36Z")

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The problem comes from the Arpack package : it works with `0.5.3` but not with `0.5.4`.