# \#eigenvectors

**URL:** https://discourse.julialang.org/tag/eigenvectors/1263.md

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## [Numerical sensitivity of eigvecs for \`≈\` identical (unitful) matrices?](https://discourse.julialang.org/t/numerical-sensitivity-of-eigvecs-for-identical-unitful-matrices/134846)

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**Author:** [@bremez](https://discourse.julialang.org/u/bremez)\
**Replies:** 3\
**Last updated:** [January 3, 2026, 2:11am UTC](https://discourse.julialang.org/t/numerical-sensitivity-of-eigvecs-for-identical-unitful-matrices/134846 "2026-01-03T02:11:09Z")

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I came across the following discrepancy, see MWE: using LinearAlgebra, Unitful GHz = 1u"GHz"; wq = 6.7565\*GHz; wc = 20\*GHz; g = 0.1847\*GHz; Ns = 10; op = diagm(1 =\> sqrt.(1:Ns)); b = kron(op, I(Ns+1)); a = kron(I(Ns+1),…

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## [Economy-sized eigendecomposition?](https://discourse.julialang.org/t/economy-sized-eigendecomposition/125037)

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**Author:** [@benninkrs](https://discourse.julialang.org/u/benninkrs)\
**Replies:** 4\
**Last updated:** [January 25, 2025, 3:29pm UTC](https://discourse.julialang.org/t/economy-sized-eigendecomposition/125037 "2025-01-25T15:29:55Z")

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Perhaps I’ve missed it, but is there a way to obtain the “economy” eigendecomposition of a matrix whose rank is less than the dimension? That is, if A is size n and rank r \< n, I would like to store just r eigenvalues a…

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## [Eigenvectors for a selected subset of eigenvalues](https://discourse.julialang.org/t/eigenvectors-for-a-selected-subset-of-eigenvalues/115213)

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**Author:** [@fgerick](https://discourse.julialang.org/u/fgerick)\
**Replies:** 0\
**Last updated:** [June 5, 2024, 6:23am UTC](https://discourse.julialang.org/t/eigenvectors-for-a-selected-subset-of-eigenvalues/115213 "2024-06-05T06:23:11Z")

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I would like to accelerate some calculations based on dense eigen spectra (non-Hermitian Matrix of dimension O(10^4)), where I’m only interested in some subset of eigenvalues (unfortunately in the middle of the spectrum,…

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## [Krylovkit tolerance changes results drastically](https://discourse.julialang.org/t/krylovkit-tolerance-changes-results-drastically/110450)

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**Author:** [@Enlil50](https://discourse.julialang.org/u/Enlil50)\
**Replies:** 0\
**Last updated:** [February 20, 2024, 11:16am UTC](https://discourse.julialang.org/t/krylovkit-tolerance-changes-results-drastically/110450 "2024-02-20T11:16:17Z")

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I’m writing a difficult to read code, just because I know the analytical result which is -0.274519. This value is meant to be compared with what is printed in the 4th column of this (a laptop is more than enough). When…

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## [Some eigenpairs from a large, sparse, nonsymmetric matrix: Julia vs Matlab](https://discourse.julialang.org/t/some-eigenpairs-from-a-large-sparse-nonsymmetric-matrix-julia-vs-matlab/93742)

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**Author:** [@PeterSimon](https://discourse.julialang.org/u/PeterSimon)\
**Replies:** 22\
**Last updated:** [January 12, 2024, 4:18am UTC](https://discourse.julialang.org/t/some-eigenpairs-from-a-large-sparse-nonsymmetric-matrix-julia-vs-matlab/93742 "2024-01-12T04:18:21Z")

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In the course of working through a book on frequency domain finite difference solutions for electromagnetics, I have been converting the supplied Matlab programs to Julia. For the problem of determining the modes of an …

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## [Eigen values and vectors sorting](https://discourse.julialang.org/t/eigen-values-and-vectors-sorting/98637)

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**Author:** [@papar](https://discourse.julialang.org/u/papar)\
**Replies:** 7\
**Last updated:** [May 10, 2023, 11:33pm UTC](https://discourse.julialang.org/t/eigen-values-and-vectors-sorting/98637 "2023-05-10T23:33:41Z")

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I am trying to work out how to sort eigen values and eigen vectors that are consistent with other languages. I use the following code on a covariance matrix: eigen\_vals, eigen\_vector = eigen(covariance\_matrix) This gi…

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## [Order of eigenvectors by using eigvecs()](https://discourse.julialang.org/t/order-of-eigenvectors-by-using-eigvecs/95048)

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**Author:** [@jisutich](https://discourse.julialang.org/u/jisutich)\
**Replies:** 2\
**Last updated:** [February 27, 2023, 10:47pm UTC](https://discourse.julialang.org/t/order-of-eigenvectors-by-using-eigvecs/95048 "2023-02-27T22:47:41Z")

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Hi, I have a very simple question. Suppose I have a Hermitian matrix A and I want to calculate its eigenvectors. I can use eigvecs(A) and the columns of it are the eigenvectors. But I want to know what is the order of t…