# Latest

**URL:** https://discourse.julialang.org/latest.md?page=145

[Latest](https://discourse.julialang.org/latest.md) · [Categories](https://discourse.julialang.org/categories.md) · [Tags](https://discourse.julialang.org/tags.md)

**Page:** 146

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## [Is \`Core.Compiler.return\_type\` foldable?](https://discourse.julialang.org/t/is-core-compiler-return-type-foldable/130173)

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**Author:** [@MilesCranmer](https://discourse.julialang.org/u/MilesCranmer)\
**Replies:** 19\
**Last updated:** [June 24, 2025, 10:27pm UTC](https://discourse.julialang.org/t/is-core-compiler-return-type-foldable/130173 "2025-06-24T22:27:53Z")

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Let’s say I want to introduce the following utility function in my library so I have a way of type stable get!ing on generic dictionaries: function stable\_get!(f::F, dict, key) where {F} return get!(f, dict, key)::(…

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## [Error adding package from local registry: , Class:SSH, failed to set hostkey preference](https://discourse.julialang.org/t/error-adding-package-from-local-registry-class-ssh-failed-to-set-hostkey-preference/130183)

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**Author:** [@Christopher\_Fisher](https://discourse.julialang.org/u/Christopher_Fisher)\
**Replies:** 3\
**Last updated:** [June 24, 2025, 9:42pm UTC](https://discourse.julialang.org/t/error-adding-package-from-local-registry-class-ssh-failed-to-set-hostkey-preference/130183 "2025-06-24T21:42:10Z")

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I’ve been working with a local registry on a Windows computer for a while. After an update, I receive the following error: (Environment) pkg\> add TrueAndErrorModels Resolving package versions... Cloning \[260ba6b…

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## [Add elements to tuples or arrays](https://discourse.julialang.org/t/add-elements-to-tuples-or-arrays/75885)

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**Author:** [@Leticia-maria](https://discourse.julialang.org/u/Leticia-maria)\
**Replies:** 32\
**Last updated:** [June 24, 2025, 9:39pm UTC](https://discourse.julialang.org/t/add-elements-to-tuples-or-arrays/75885 "2025-06-24T21:39:03Z")

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Hi everyone, do you know a way to have this working on Julia REPL? \>\>\> a = \[1,2,3\] \>\>\> a + \[4\] \[1, 2, 3, 4\]

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## [The package \*\*FowardDiff.jl\*\* could not load because it failed to initialize](https://discourse.julialang.org/t/the-package-fowarddiff-jl-could-not-load-because-it-failed-to-initialize/130180)

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**Author:** [@Miguel](https://discourse.julialang.org/u/Miguel)\
**Replies:** 3\
**Last updated:** [June 24, 2025, 9:16pm UTC](https://discourse.julialang.org/t/the-package-fowarddiff-jl-could-not-load-because-it-failed-to-initialize/130180 "2025-06-24T21:16:50Z")

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The package FowardDiff.jl could not load because it failed to initialize. That’s not nice! Things you could try: \*\*\* Restart the notebook.\*\* \*\*\* Try a different Julia version.\*\* \*\*\* Contact the developers of FowardDi…

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## [Modifying subentries in a Vector{SVector}, @set and reinterpret](https://discourse.julialang.org/t/modifying-subentries-in-a-vector-svector-set-and-reinterpret/130178)

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**Author:** [@eldee](https://discourse.julialang.org/u/eldee)\
**Replies:** 1\
**Last updated:** [June 24, 2025, 7:41pm UTC](https://discourse.julialang.org/t/modifying-subentries-in-a-vector-svector-set-and-reinterpret/130178 "2025-06-24T19:41:58Z")

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Hi, Most of the time it makes conceptually more sense to store some data as a Vector{SVector{Float64, 3}} v as opposed to a Matrix{Float64} M of size (3, n). However, this makes updating (sub)entries more difficult. I.…

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## [Agent based network model using EventQueueABM](https://discourse.julialang.org/t/agent-based-network-model-using-eventqueueabm/129889)

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**Author:** [@zoek](https://discourse.julialang.org/u/zoek)\
**Replies:** 15\
**Last updated:** [June 24, 2025, 7:33pm UTC](https://discourse.julialang.org/t/agent-based-network-model-using-eventqueueabm/129889 "2025-06-24T19:33:02Z")

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Hello, I’m trying to use EventQueueABM from agents.jl on a completely connected network to model disease spread (susceptible, exposed, infected and recovered states). Since it’s completely connected, I believe I should b…

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## [Using JuMP for solving a symbolic algebraic system](https://discourse.julialang.org/t/using-jump-for-solving-a-symbolic-algebraic-system/130153)

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**Author:** [@jonlym](https://discourse.julialang.org/u/jonlym)\
**Replies:** 2\
**Last updated:** [June 24, 2025, 7:00pm UTC](https://discourse.julialang.org/t/using-jump-for-solving-a-symbolic-algebraic-system/130153 "2025-06-24T19:00:05Z")

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Hi All, I’d like to solve a system of algebraic equations with the flexibility to specify one variable as independent and one as the dependent variable. In the toy example below, I am calculating the Reynolds number, Re …

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## [KNITRO license path](https://discourse.julialang.org/t/knitro-license-path/130145)

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**Author:** [@CeterisPartybus](https://discourse.julialang.org/u/CeterisPartybus)\
**Replies:** 4\
**Last updated:** [June 24, 2025, 6:42pm UTC](https://discourse.julialang.org/t/knitro-license-path/130145 "2025-06-24T18:42:53Z")

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From where does Julia in VS Code source environmental variables setting the KNITRO license path ENV\[“ARTELYS\_LICENSE”\]? The issue: I updated my KNITRO license file and its location and set the environment variable in .…

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## [Solvers for Block-Tridiagonal](https://discourse.julialang.org/t/solvers-for-block-tridiagonal/130013)

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**Author:** [@rsenne](https://discourse.julialang.org/u/rsenne)\
**Replies:** 14\
**Last updated:** [June 24, 2025, 6:41pm UTC](https://discourse.julialang.org/t/solvers-for-block-tridiagonal/130013 "2025-06-24T18:41:55Z")

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Block Tridiagonal Linear System Performance: Custom vs Package Implementations I recently submitted an issue to BlockBandedMatrices.jl about this, but thought it might be interesting to the broader community. Problem I …

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## [What's the feasibility of and interest in tooling for building desktop science, engineering and analysis tools?](https://discourse.julialang.org/t/whats-the-feasibility-of-and-interest-in-tooling-for-building-desktop-science-engineering-and-analysis-tools/130094)

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**Author:** [@MDSW](https://discourse.julialang.org/u/MDSW)\
**Replies:** 3\
**Last updated:** [June 24, 2025, 6:41pm UTC](https://discourse.julialang.org/t/whats-the-feasibility-of-and-interest-in-tooling-for-building-desktop-science-engineering-and-analysis-tools/130094 "2025-06-24T18:41:41Z")

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I’ve been doing some small proof-of-concepts while getting deeper on some of the technical aspects of Julia around compilation and deployment packaging. I’m drawn to Julia as a result of having seen the challenges with t…

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## [Matrix multiplication and vector multiplication give different results!](https://discourse.julialang.org/t/matrix-multiplication-and-vector-multiplication-give-different-results/130177)

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**Author:** [@tomtom](https://discourse.julialang.org/u/tomtom)\
**Replies:** 4\
**Last updated:** [June 24, 2025, 5:04pm UTC](https://discourse.julialang.org/t/matrix-multiplication-and-vector-multiplication-give-different-results/130177 "2025-06-24T17:04:11Z")

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I found that (slightly) different results coming from matrix-matrix vs. matrix-vector multiplication! julia\> m1 = randn(200, 300); julia\> m2 = randn(300, 400); julia\> m12 = m1 \* m2; # matrix-matrix multiplicati…

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## [Is Juliacon housing favouring students?](https://discourse.julialang.org/t/is-juliacon-housing-favouring-students/128935)

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**Author:** [@cstjean](https://discourse.julialang.org/u/cstjean)\
**Replies:** 3\
**Last updated:** [June 24, 2025, 2:41pm UTC](https://discourse.julialang.org/t/is-juliacon-housing-favouring-students/128935 "2025-06-24T14:41:23Z")

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Continuing the discussion from \[JuliaCon\] Housing is now available for purchase for JuliaCon 2025!: The Juliacon housing looks like a great deal, even just for the social / logistic aspect. However: @rayegun Should th…

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## [Training Neural ODEs - Advice](https://discourse.julialang.org/t/training-neural-odes-advice/130141)

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**Author:** [@julianewbsourcream](https://discourse.julialang.org/u/julianewbsourcream)\
**Replies:** 2\
**Last updated:** [June 24, 2025, 1:49pm UTC](https://discourse.julialang.org/t/training-neural-odes-advice/130141 "2025-06-24T13:49:26Z")

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Hi, I am looking for some advice about training neural ODE models. I am looking to train a neural ODE model on a sample of ~25000, 10x4000 matrices. The columns represent time so I was looking to at use an increasing am…

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## [Optional argument in macro](https://discourse.julialang.org/t/optional-argument-in-macro/130057)

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**Author:** [@alex180500](https://discourse.julialang.org/u/alex180500)\
**Replies:** 8\
**Last updated:** [June 24, 2025, 12:46pm UTC](https://discourse.julialang.org/t/optional-argument-in-macro/130057 "2025-06-24T12:46:48Z")

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I’m creating my custom progress bar for my ML related loop. It’s based on ProgressMeter.jl. The macro takes an argument as input that is a dictionary associating names to vectors of data that I’m saving during the comput…

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## [Extracting internally computed array from \`KrylovKit.eigsolve\` (without forking)](https://discourse.julialang.org/t/extracting-internally-computed-array-from-krylovkit-eigsolve-without-forking/130161)

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**Author:** [@NitinGupta](https://discourse.julialang.org/u/NitinGupta)\
**Replies:** 6\
**Last updated:** [June 24, 2025, 12:51pm UTC](https://discourse.julialang.org/t/extracting-internally-computed-array-from-krylovkit-eigsolve-without-forking/130161 "2025-06-24T12:51:59Z")

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I’d like to access the array T defined at line 44 of KrylovKit.jl/src/eigsolve/lanczos external to the function KrylovKit.eigsolve i.e. I want that eigsolve return T as well. What is the best way to go about this withou…

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## [Exact Cygwin package versions when building Julia](https://discourse.julialang.org/t/exact-cygwin-package-versions-when-building-julia/130162)

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**Author:** [@gitboy16](https://discourse.julialang.org/u/gitboy16)\
**Replies:** 0\
**Last updated:** [June 24, 2025, 10:58am UTC](https://discourse.julialang.org/t/exact-cygwin-package-versions-when-building-julia/130162 "2025-06-24T10:58:56Z")

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Hi, I have moved to a new computer and struggling to build Julia from source on Windows with Cygwin. I am getting a message error saying: fatal error: mm\_malloc.h : No such file or directory. Is there a way to know w…

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## [How to forward differentiate a complex function?](https://discourse.julialang.org/t/how-to-forward-differentiate-a-complex-function/130127)

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**Author:** [@albertomercurio](https://discourse.julialang.org/u/albertomercurio)\
**Replies:** 19\
**Last updated:** [June 24, 2025, 10:13am UTC](https://discourse.julialang.org/t/how-to-forward-differentiate-a-complex-function/130127 "2025-06-24T10:13:02Z")

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Hello, I have a very basic question, but I haven’t found any solution. I want to differentiate a holomorphic complex function. My function is f(z) = \[z^3 + exp(im\*z), exp(im\*z^2) + 1\] And I differentiate it using Dif…

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## [Sorting when the comparison operator depends on the entire input vector](https://discourse.julialang.org/t/sorting-when-the-comparison-operator-depends-on-the-entire-input-vector/130152)

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**Author:** [@colintbowers](https://discourse.julialang.org/u/colintbowers)\
**Replies:** 6\
**Last updated:** [June 24, 2025, 6:04am UTC](https://discourse.julialang.org/t/sorting-when-the-comparison-operator-depends-on-the-entire-input-vector/130152 "2025-06-24T06:04:22Z")

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Hi all. Given a parameter Vector{Float64} called x, I want to find x\* such that f(x\*) \> f(x) for all possible permutations of x, where f maps x to a single Float64. I could (and have successfully) used a general optimiza…

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## [Problem loading ducklake extension](https://discourse.julialang.org/t/problem-loading-ducklake-extension/130154)

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**Author:** [@kobusherbst](https://discourse.julialang.org/u/kobusherbst)\
**Replies:** 1\
**Last updated:** [June 24, 2025, 5:24am UTC](https://discourse.julialang.org/t/problem-loading-ducklake-extension/130154 "2025-06-24T05:24:28Z")

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When trying to load the ducklake extension in DuckDB v1.3.1 I get the following error: ERROR: Execute of query "LOAD ducklake;" failed: HTTP Error: Failed to download extension "ducklake" at URL "http://extensions.duckd…

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## [WunDeeDB.jl a lightweight sqlite backed vector database](https://discourse.julialang.org/t/wundeedb-jl-a-lightweight-sqlite-backed-vector-database/130151)

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**Author:** [@mantzaris](https://discourse.julialang.org/u/mantzaris)\
**Replies:** 0\
**Last updated:** [June 24, 2025, 1:11am UTC](https://discourse.julialang.org/t/wundeedb-jl-a-lightweight-sqlite-backed-vector-database/130151 "2025-06-24T01:11:34Z")

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WunDeeDB.jl: An easy to use, zero config, WAL, SQLite backend vector database Is now in the general repository, GitHub - mantzaris/WunDeeDB.jl: Your just-works / zero-config / embedded / WAL: vector database What WunDe…

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## ['Python can run Mojo now' :: What would the equivalent Julia look like?](https://discourse.julialang.org/t/python-can-run-mojo-now-what-would-the-equivalent-julia-look-like/130135)

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**Author:** [@MDSW](https://discourse.julialang.org/u/MDSW)\
**Replies:** 1\
**Last updated:** [June 23, 2025, 11:14pm UTC](https://discourse.julialang.org/t/python-can-run-mojo-now-what-would-the-equivalent-julia-look-like/130135 "2025-06-23T23:14:41Z")

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Since I often get asked about Mojo when advocating for Julia these days, I’m curious when I see an article like this: Python can run Mojo now | Vincent D. Warmerdam . What would the equivalent call out from Python to J…

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## [Do you use SolveDSGE.jl, ChebyshevApprox.jl, SmolyakApprox.jl, HyperbolicCrossApprox.jl or NLboxsolve.jl?](https://discourse.julialang.org/t/do-you-use-solvedsge-jl-chebyshevapprox-jl-smolyakapprox-jl-hyperboliccrossapprox-jl-or-nlboxsolve-jl/130146)

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**Author:** [@RJDennis](https://discourse.julialang.org/u/RJDennis)\
**Replies:** 0\
**Last updated:** [June 23, 2025, 11:12pm UTC](https://discourse.julialang.org/t/do-you-use-solvedsge-jl-chebyshevapprox-jl-smolyakapprox-jl-hyperboliccrossapprox-jl-or-nlboxsolve-jl/130146 "2025-06-23T23:12:08Z")

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Hi All, in UK academia we have these periodic REF review exercises. The next one is a few years away, but planning and prreparation are already underway. One of the things that the REF looks into is “impact”, which ca…

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## [RECS: A Reactive ECS Framework for High-Performance Simulations in Julia](https://discourse.julialang.org/t/recs-a-reactive-ecs-framework-for-high-performance-simulations-in-julia/130098)

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**Author:** [@Gesee](https://discourse.julialang.org/u/Gesee)\
**Replies:** 16\
**Last updated:** [June 23, 2025, 5:09pm UTC](https://discourse.julialang.org/t/recs-a-reactive-ecs-framework-for-high-performance-simulations-in-julia/130098 "2025-06-23T17:09:00Z")

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I am thrilled to introduce RECS (Reactive Entity-Component-System), a new Julia package designed for building high-performance, modular, and reactive simulations, with a focus on game development and scientific applicati…

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## [SDDP model sometimes fails during training, or simulation](https://discourse.julialang.org/t/sddp-model-sometimes-fails-during-training-or-simulation/130139)

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**Author:** [@slwu89](https://discourse.julialang.org/u/slwu89)\
**Replies:** 2\
**Last updated:** [June 23, 2025, 9:49pm UTC](https://discourse.julialang.org/t/sddp-model-sometimes-fails-during-training-or-simulation/130139 "2025-06-23T21:49:33Z")

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Hi all. I’m seeking help to diagnose a simple inventory problem over a finite horizon I’ve set up with SDDP. Currently, my model is such that the stochasticity is demand, for which we assume we know the intensity of the …

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## [How to best check in on a job application via email?](https://discourse.julialang.org/t/how-to-best-check-in-on-a-job-application-via-email/130126)

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**Author:** [@xiaodai](https://discourse.julialang.org/u/xiaodai)\
**Replies:** 5\
**Last updated:** [June 23, 2025, 9:37pm UTC](https://discourse.julialang.org/t/how-to-best-check-in-on-a-job-application-via-email/130126 "2025-06-23T21:37:04Z")

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I interviewed for a leadership role but was not selected. I want to send some emails to the recruiter and interviewer to show my appreciation. I drafted the email with AI and I changed the language a bit to get rid bits …

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## [Has anyone added a MyST markdown extension to Julia?](https://discourse.julialang.org/t/has-anyone-added-a-myst-markdown-extension-to-julia/83289)

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**Author:** [@cadojo](https://discourse.julialang.org/u/cadojo)\
**Replies:** 3\
**Last updated:** [June 23, 2025, 9:01pm UTC](https://discourse.julialang.org/t/has-anyone-added-a-myst-markdown-extension-to-julia/83289 "2025-06-23T21:01:22Z")

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The good folks over at Executable Books have developed a new markdown flavor which adds support for function-like operations, citations, custom labeling, and more. The new markdown flavor is called MyST. Is this availa…

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## [How to properly do thread-safe element-wise mutation on atomic fields?](https://discourse.julialang.org/t/how-to-properly-do-thread-safe-element-wise-mutation-on-atomic-fields/130138)

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**Author:** [@frankwswang](https://discourse.julialang.org/u/frankwswang)\
**Replies:** 4\
**Last updated:** [June 23, 2025, 7:57pm UTC](https://discourse.julialang.org/t/how-to-properly-do-thread-safe-element-wise-mutation-on-atomic-fields/130138 "2025-06-23T19:57:52Z")

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MWE: julia\> mutable struct Atomic{T} @atomic a::T end julia\> obj1 = Atomic(collect(1:4)) Atomic{Vector{Int64}}(\[1, 2, 3, 4\]) julia\> obj1.a .= 2 4-element Vector{Int64}: 2 2 2 2 Unlike directly c…

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## [How to get ranges of valid data in vectors or dataframes?](https://discourse.julialang.org/t/how-to-get-ranges-of-valid-data-in-vectors-or-dataframes/129985)

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**Author:** [@Ju\_ska](https://discourse.julialang.org/u/Ju_ska)\
**Replies:** 7\
**Last updated:** [June 23, 2025, 6:59pm UTC](https://discourse.julialang.org/t/how-to-get-ranges-of-valid-data-in-vectors-or-dataframes/129985 "2025-06-23T18:59:08Z")

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Hi, using DataFrames df = DataFrame(col1 = \[1, NaN, 3, 4, NaN, 6, 7, 8, 9, 10, NaN, NaN\], col2 = \[missing, 2, 3, 4, 5, 6, missing, 8, 9, 10, 11, 12\]) 12×2 DataFrame Row │ col1 col2 │ Float64 Int64? ──…

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## [ExponentialUtilities.jl expv!() allocations](https://discourse.julialang.org/t/exponentialutilities-jl-expv-allocations/129917)

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**Author:** [@random\_guy](https://discourse.julialang.org/u/random_guy)\
**Replies:** 11\
**Last updated:** [June 23, 2025, 4:56pm UTC](https://discourse.julialang.org/t/exponentialutilities-jl-expv-allocations/129917 "2025-06-23T16:56:05Z")

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Hi everyone, I’m trying to use Julia’s ExponentialUtilities.jl package to perform matrix-exponential-matrix multiplication. I have a sparse NxN Hamiltonian H, a small time step dt, and an NxN matrix A. The goal is to co…

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## [Nested loop in @mtkmodel / Matrix manipulation](https://discourse.julialang.org/t/nested-loop-in-mtkmodel-matrix-manipulation/130133)

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**Author:** [@madtorresga](https://discourse.julialang.org/u/madtorresga)\
**Replies:** 2\
**Last updated:** [June 23, 2025, 4:56pm UTC](https://discourse.julialang.org/t/nested-loop-in-mtkmodel-matrix-manipulation/130133 "2025-06-23T16:56:09Z")

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Hi :slight\_smile: I’m trying to automate the battery cells’ creation from an already defined ECM model: const Qs = \[4.8 4.4 4.2 ; 3.7 3.5 3.3\] @mtkmodel Series\_Connection begin @variables begin v\_max …

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