# Some eigenpairs from a large, sparse, nonsymmetric matrix: Julia vs Matlab

**URL:** https://discourse.julialang.org/t/some-eigenpairs-from-a-large-sparse-nonsymmetric-matrix-julia-vs-matlab/93742
**Category:** Numerics
**Tags:** sparse, eigenvalues, eigenvectors
**Created:** [January 29, 2023, 7:35pm UTC](https://discourse.julialang.org/t/some-eigenpairs-from-a-large-sparse-nonsymmetric-matrix-julia-vs-matlab/93742 "2023-01-29T19:35:54Z")
**Posts on this page:** 3
**Page:** 2

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### Author: ![Ian\_L](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/ian_l/32/49509_2.png) [@Ian\_L](https://discourse.julialang.org/u/Ian_L)
#### Post date: [May 29, 2023, 9:03pm UTC](https://discourse.julialang.org/t/some-eigenpairs-from-a-large-sparse-nonsymmetric-matrix-julia-vs-matlab/93742/21 "2023-05-29T21:03:25Z")

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With SuiteSparse merged into SparseArrays, `UMFPACK.umf_ctrl` doesn’t appeared defined? How would one do this now?

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### Author: ![Ralph\_Smith](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/ralph_smith/32/10344_2.png) [@Ralph\_Smith](https://discourse.julialang.org/u/Ralph_Smith)
#### Post date: [May 29, 2023, 11:48pm UTC](https://discourse.julialang.org/t/some-eigenpairs-from-a-large-sparse-nonsymmetric-matrix-julia-vs-matlab/93742/22 "2023-05-29T23:48:48Z")

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Refinement is now (Julia v1.9) omitted by default in sparse LU; see [this issue](https://github.com/JuliaSparse/SparseArrays.jl/issues/122) for discussion.

It can be enabled by setting element `JL_UMFPACK_IRSTEP` in the default table returned by `get_umfpack_control()` (both are in `SparseArrays.UMFPACK`). The old value was 2.0.

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### Author: ![mkitti](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/mkitti/32/12459_2.png) [@mkitti](https://discourse.julialang.org/u/mkitti)
#### Post date: [January 12, 2024, 4:18am UTC](https://discourse.julialang.org/t/some-eigenpairs-from-a-large-sparse-nonsymmetric-matrix-julia-vs-matlab/93742/23 "2024-01-12T04:18:21Z")

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> [@jonas-kr](#):
>
> Actually, Matlab does not use Arpack anymore. Instead, they have implemented their own version of the Krylov-Schur method accessible from the Matlab prompt with `edit eigs.m`.

This is great information, but we need to be very careful about looking at MATLAB source code. It is not free (libre) to copy from.

I would advise anyone trying to implement Krylov-Schur methods not to look at `eigs.m`.

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