# \#linear-algebra

**URL:** https://discourse.julialang.org/tag/linear-algebra/577.md

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## [3D engine for visualizing linear transformations and their decompositions](https://discourse.julialang.org/t/3d-engine-for-visualizing-linear-transformations-and-their-decompositions/136631)

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**Author:** [@GraphMath](https://discourse.julialang.org/u/GraphMath)\
**Replies:** 6\
**Last updated:** [April 10, 2026, 12:08pm UTC](https://discourse.julialang.org/t/3d-engine-for-visualizing-linear-transformations-and-their-decompositions/136631 "2026-04-10T12:08:42Z")

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We built a 3D visualization engine to represent linear transformations in ℝ³ as compositions of simpler transformations. In this example, A = QR Image shows deformation followed by rigid motion. Can generate additi…

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## [Multithreading non-contiguous mapreduction over huge matrices](https://discourse.julialang.org/t/multithreading-non-contiguous-mapreduction-over-huge-matrices/134413)

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**Author:** [@noetheriankoala](https://discourse.julialang.org/u/noetheriankoala)\
**Replies:** 5\
**Last updated:** [December 8, 2025, 7:36am UTC](https://discourse.julialang.org/t/multithreading-non-contiguous-mapreduction-over-huge-matrices/134413 "2025-12-08T07:36:45Z")

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Hello! A version of the following function is majorly bottle-necking a project I am working on and I could use help speeding it up. In all the below code, A is an k x n matrix, l is a length-n vector, and q is a length n…

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## [Parallel Processing and Eigenvalue calculation](https://discourse.julialang.org/t/parallel-processing-and-eigenvalue-calculation/131659)

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**Author:** [@FranciscoZick](https://discourse.julialang.org/u/FranciscoZick)\
**Replies:** 2\
**Last updated:** [August 18, 2025, 9:41am UTC](https://discourse.julialang.org/t/parallel-processing-and-eigenvalue-calculation/131659 "2025-08-18T09:41:41Z")

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Hey everyone, I’m not necessarily new to Julia but new to parallel processing and writing fast code. I am trying to optimize this piece of code: BLAS.set\_num\_threads(16) MAX\_CONC = 4 # limit to 4 concurrent tasks @s…

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## [Faster way to peform rank-1 update to matrix inverse](https://discourse.julialang.org/t/faster-way-to-peform-rank-1-update-to-matrix-inverse/129001)

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**Author:** [@Kieran\_Marray](https://discourse.julialang.org/u/Kieran_Marray)\
**Replies:** 5\
**Last updated:** [May 15, 2025, 9:10am UTC](https://discourse.julialang.org/t/faster-way-to-peform-rank-1-update-to-matrix-inverse/129001 "2025-05-15T09:10:45Z")

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I want to update a matrix inverse using the Sherman-Morrison formula (A + uv’)^-1 = A^-1 - (A^-1 uv’ A^-1)/(1 + v’A^-1u) for a large non-sparse matrix inside a loop (a coordinate descent algorithm). Here is a minimum …

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## [New Package: Matroids](https://discourse.julialang.org/t/new-package-matroids/125716)

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**Author:** [@scheinerman](https://discourse.julialang.org/u/scheinerman)\
**Replies:** 0\
**Last updated:** [February 10, 2025, 1:25am UTC](https://discourse.julialang.org/t/new-package-matroids/125716 "2025-02-10T01:25:48Z")

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I am pleased to announce the creation of a Matroids module for Julia. Matroids provide an abstract notion of linear independence, and may be considered a generalization of matrices and graphs. Roughly speaking, they are…

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## [Accelerating repeated eigenvalue searches](https://discourse.julialang.org/t/accelerating-repeated-eigenvalue-searches/114989)

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**Author:** [@bremez](https://discourse.julialang.org/u/bremez)\
**Replies:** 31\
**Last updated:** [June 14, 2024, 2:08pm UTC](https://discourse.julialang.org/t/accelerating-repeated-eigenvalue-searches/114989 "2024-06-14T14:08:23Z")

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I need to compute the eigenvalues of 2N\\times2N (N ~ 1000) complex, hermitian, dense, matrices, the number of matrices being ~100. They have the following properties: All matrices M\_i take the form M\_i = A + D\_i, where…

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## [LibCEED.jl: do you use it?](https://discourse.julialang.org/t/libceed-jl-do-you-use-it/110737)

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**Author:** [@PetrKryslUCSD](https://discourse.julialang.org/u/PetrKryslUCSD)\
**Replies:** 0\
**Last updated:** [February 25, 2024, 2:04pm UTC](https://discourse.julialang.org/t/libceed-jl-do-you-use-it/110737 "2024-02-25T14:04:56Z")

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I’d be interested in looking at some use cases for this library. If your package is on Github, do let me know. Many thanks!

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## [Inplace version for LU decomposition in Julia](https://discourse.julialang.org/t/inplace-version-for-lu-decomposition-in-julia/108795)

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**Author:** [@mrVeng](https://discourse.julialang.org/u/mrVeng)\
**Replies:** 8\
**Last updated:** [January 15, 2024, 2:55pm UTC](https://discourse.julialang.org/t/inplace-version-for-lu-decomposition-in-julia/108795 "2024-01-15T14:55:06Z")

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Hi there! I have to compute the lu decomposition of a matrix that is dependent - I was thinking to create a buffer first and then inplace compute the lu decomposition when needed, but after googling and searching throug…

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## [Compiler matmul optimization prevents constant folding?](https://discourse.julialang.org/t/compiler-matmul-optimization-prevents-constant-folding/107121)

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**Author:** [@bremez](https://discourse.julialang.org/u/bremez)\
**Replies:** 18\
**Last updated:** [December 4, 2023, 5:50pm UTC](https://discourse.julialang.org/t/compiler-matmul-optimization-prevents-constant-folding/107121 "2023-12-04T17:50:29Z")

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I have a use case where I iterate over a container of small vectors. Say vs is a Vector{SVector{2, Float64}}, M is a global constant SMatrix{2,2,Float64,4}, and an illustrative use case is function f(vs) total = zero(el…

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## [Principal angles between subspaces](https://discourse.julialang.org/t/principal-angles-between-subspaces/101044)

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**Author:** [@fph](https://discourse.julialang.org/u/fph)\
**Replies:** 2\
**Last updated:** [July 1, 2023, 12:53pm UTC](https://discourse.julialang.org/t/principal-angles-between-subspaces/101044 "2023-07-01T12:53:42Z")

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Does Julia have a function to compute canonical / principal angles between subspaces, like scipy.linalg.subspace\_angles or even just Matlab’s subspace which computes the maximum angle only? The computation is essentiall…

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## [Vmls - sum of vectors, displacement](https://discourse.julialang.org/t/vmls-sum-of-vectors-displacement/93779)

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**Author:** [@jcbritobr](https://discourse.julialang.org/u/jcbritobr)\
**Replies:** 5\
**Last updated:** [January 30, 2023, 7:52pm UTC](https://discourse.julialang.org/t/vmls-sum-of-vectors-displacement/93779 "2023-01-30T19:52:33Z")

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Hello, good afternoon. I’m reading the VMLS book introduction about algebra linear and trying to draw the vector displacement in a plot. When sum two vectors a and b, the a+b vector dont need to connect to the end of b…

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## [Inplace multiplication of sub-matrices without allocations](https://discourse.julialang.org/t/inplace-multiplication-of-sub-matrices-without-allocations/91534)

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**Author:** [@CeterisPartybus](https://discourse.julialang.org/u/CeterisPartybus)\
**Replies:** 12\
**Last updated:** [December 12, 2022, 8:44pm UTC](https://discourse.julialang.org/t/inplace-multiplication-of-sub-matrices-without-allocations/91534 "2022-12-12T20:44:36Z")

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I am writing a performance-critical part and would like to avoid any memory allocations in that part by creating caches beforehand. I then essentially need to multiply sub-arrays in a loop. Is there any way to do these m…

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## [Dependency Error :'(](https://discourse.julialang.org/t/dependency-error/90262)

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**Author:** [@chelseas](https://discourse.julialang.org/u/chelseas)\
**Replies:** 2\
**Last updated:** [November 14, 2022, 10:05pm UTC](https://discourse.julialang.org/t/dependency-error/90262 "2022-11-14T22:05:14Z")

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I am getting this error from my use of BlockDiagonals: ERROR: Unsatisfiable requirements detected for package BlockDiagonals \[0a1fb500\]: BlockDiagonals \[0a1fb500\] log: ├─BlockDiagonals \[0a1fb500\] has no known versions…

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## [Linear Algebra Application: Warps and Morphs in Julia](https://discourse.julialang.org/t/linear-algebra-application-warps-and-morphs-in-julia/83716)

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**Author:** [@Freya\_the\_Goddess](https://discourse.julialang.org/u/Freya_the_Goddess)\
**Replies:** 0\
**Last updated:** [July 4, 2022, 12:55am UTC](https://discourse.julialang.org/t/linear-algebra-application-warps-and-morphs-in-julia/83716 "2022-07-04T00:55:09Z")

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Hi all, I am reading Linear Algebra book and I am wondering, is Julia capable of doing warps and morphs? The example is attached (a picture of a projection how someone will get old). Anyone ever done similar thing here…