# \#arpack

**URL:** https://discourse.julialang.org/tag/arpack/940.md

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## [Large Sparse Hermitian Matrix - Intermediate Eigenvalue Problem](https://discourse.julialang.org/t/large-sparse-hermitian-matrix-intermediate-eigenvalue-problem/131600)

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**Author:** [@Neilis](https://discourse.julialang.org/u/Neilis)\
**Replies:** 9\
**Last updated:** [September 23, 2025, 2:22pm UTC](https://discourse.julialang.org/t/large-sparse-hermitian-matrix-intermediate-eigenvalue-problem/131600 "2025-09-23T14:22:14Z")

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Hi, I am trying to find eigenvalues and eigenvectors for a rather large, sparse, hermitian matrix (size ~1E7 x 1E7). I am mainly interested in around 40 eigenvalues in the middle of the spectrum. To solve this original…

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## [Efficient representation of a sparse "pentadiagonal" matrix?](https://discourse.julialang.org/t/efficient-representation-of-a-sparse-pentadiagonal-matrix/131744)

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**Author:** [@bremez](https://discourse.julialang.org/u/bremez)\
**Replies:** 8\
**Last updated:** [August 21, 2025, 6:53pm UTC](https://discourse.julialang.org/t/efficient-representation-of-a-sparse-pentadiagonal-matrix/131744 "2025-08-21T18:53:13Z")

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I am interested in the eigenspectrum of Hermitian matrices that have a “pentadiagonal” structure, with A\[m,n\]=0 if abs(m-n)\>2. I am most interested in eigenstates with values close to zero. At present I am using Arpack.j…

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## [How can I give a function to eigs() in julia like matlab](https://discourse.julialang.org/t/how-can-i-give-a-function-to-eigs-in-julia-like-matlab/105699)

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**Author:** [@Meteoooor](https://discourse.julialang.org/u/Meteoooor)\
**Replies:** 6\
**Last updated:** [November 3, 2023, 7:57am UTC](https://discourse.julialang.org/t/how-can-i-give-a-function-to-eigs-in-julia-like-matlab/105699 "2023-11-03T07:57:05Z")

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I have the following matlab code: function \[ DomRVec, DomEig, Error \] = MyEigs( Tup, Tdn, NumofValue, SpeString, Dbond, Dspin, InitVec ) VecDim = Dbond^2; Tup = reshape( permute( Tup, \[ 1, 3, 2 \] ), \[ Dbond \* Dspin, D…

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## [Suggestions needed: diagonalizing large Hermitian sparse matrix](https://discourse.julialang.org/t/suggestions-needed-diagonalizing-large-hermitian-sparse-matrix/96580)

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**Author:** [@Chong\_Wang](https://discourse.julialang.org/u/Chong_Wang)\
**Replies:** 4\
**Last updated:** [April 3, 2023, 6:03am UTC](https://discourse.julialang.org/t/suggestions-needed-diagonalizing-large-hermitian-sparse-matrix/96580 "2023-04-03T06:03:37Z")

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I need to find a few eigenvalues and eigenvectors of some large Hermitian sparse matrices. Right now, I am trying Arpack.jl and KrylovKit.jl. Here are some considerations and my experiences. Arpack.jl does not have sp…

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## [Tracking down a dyld error on apple silicon](https://discourse.julialang.org/t/tracking-down-a-dyld-error-on-apple-silicon/89240)

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**Author:** [@cmarcotte](https://discourse.julialang.org/u/cmarcotte)\
**Replies:** 0\
**Last updated:** [October 25, 2022, 8:22am UTC](https://discourse.julialang.org/t/tracking-down-a-dyld-error-on-apple-silicon/89240 "2022-10-25T08:22:04Z")

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Hello Julians, I am trying to track down a dyld error on Apple Silicon when using the UMAP.jl package. Under rosetta it works perfectly well, but in 1.8.2 (native) I get the following error when add-ing and then test-in…

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## [Sort the output of eigs by the eigenvalues](https://discourse.julialang.org/t/sort-the-output-of-eigs-by-the-eigenvalues/79455)

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**Author:** [@ahmed](https://discourse.julialang.org/u/ahmed)\
**Replies:** 6\
**Last updated:** [April 14, 2022, 12:14am UTC](https://discourse.julialang.org/t/sort-the-output-of-eigs-by-the-eigenvalues/79455 "2022-04-14T00:14:07Z")

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I’m using eigs to find the two eigenvalues with the largest magnitude near a value sigma. One of the eigenvalues is negative while the other is positive. How can I get eigs to give me the eigenvalues/eigenvectors sorted …

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## [Smallest magnitude eigenvalues of the generalized eigenvalue equation for a large sparse matrix](https://discourse.julialang.org/t/smallest-magnitude-eigenvalues-of-the-generalized-eigenvalue-equation-for-a-large-sparse-matrix/75485)

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**Author:** [@Chong\_Wang](https://discourse.julialang.org/u/Chong_Wang)\
**Replies:** 20\
**Last updated:** [February 2, 2022, 12:05pm UTC](https://discourse.julialang.org/t/smallest-magnitude-eigenvalues-of-the-generalized-eigenvalue-equation-for-a-large-sparse-matrix/75485 "2022-02-02T12:05:42Z")

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I have a generalized eigenvalue problem Hx=\\lambda S x to solve, where H is Hermitian and S is positive definite. Both H and S are sparse matrices and their dimensions (size(H, 1)) are on the order of 10^5. Roughly 1% of…