# Latest

**URL:** https://discourse.julialang.org/latest.md?page=308

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

**Page:** 309

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## [How to calculate opnorm for a sparse matrix in julia?](https://discourse.julialang.org/t/how-to-calculate-opnorm-for-a-sparse-matrix-in-julia/120820)

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**Author:** [@usaer](https://discourse.julialang.org/u/usaer)\
**Replies:** 3\
**Last updated:** [October 2, 2024, 5:04pm UTC](https://discourse.julialang.org/t/how-to-calculate-opnorm-for-a-sparse-matrix-in-julia/120820 "2024-10-02T17:04:31Z")

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Please guide on how to calculate the opnorm for p=2 in julia for sparse matrices. When I try I get the error ArgumentError: 2-norm not yet implemented for sparse matrices. Try opnorm(Array(A)) or opnorm(A, p) where p=1 …

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## [How to run a Julia script from the command line which has package dependencies?](https://discourse.julialang.org/t/how-to-run-a-julia-script-from-the-command-line-which-has-package-dependencies/120813)

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**Author:** [@anon91151494](https://discourse.julialang.org/u/anon91151494)\
**Replies:** 4\
**Last updated:** [October 2, 2024, 3:10pm UTC](https://discourse.julialang.org/t/how-to-run-a-julia-script-from-the-command-line-which-has-package-dependencies/120813 "2024-10-02T15:10:01Z")

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I’m trying to run a Julia script like an executable program from the command line. $ julia myscript.jl If this script has dependencies on packages, such as the Distributions package, how can I run such a script from th…

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## [Change xticklabels in PolarAxis (GLMakie)](https://discourse.julialang.org/t/change-xticklabels-in-polaraxis-glmakie/120811)

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**Author:** [@NaSi](https://discourse.julialang.org/u/NaSi)\
**Replies:** 3\
**Last updated:** [October 2, 2024, 2:19pm UTC](https://discourse.julialang.org/t/change-xticklabels-in-polaraxis-glmakie/120811 "2024-10-02T14:19:11Z")

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Hello =) I work with GLMakie and I want to plot the following : rticklabels = \["a", "b", "c", "d", "e", "f", "g"\] rticks = 0:10:60 f = Figure(size = (800, 400)) ax = PolarAxis(f\[1, 1\], rticks = rticks, rticklabels = r…

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## [Yet another precompilation-on-HPC issue](https://discourse.julialang.org/t/yet-another-precompilation-on-hpc-issue/105731)

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**Author:** [@Davide\_DelVento](https://discourse.julialang.org/u/Davide_DelVento)\
**Replies:** 5\
**Last updated:** [October 2, 2024, 2:09pm UTC](https://discourse.julialang.org/t/yet-another-precompilation-on-hpc-issue/105731 "2024-10-02T14:09:58Z")

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I administer an HPC cluster and I’ve installed Julia (using spack as a package manager) globally. Spack compiled julia in /tmp/aaa/spack-stage/spack-stage-julia-1.9.2-yux5s54oyok6xiifl5xwqeqjljazifjg/spack-src/ and then …

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## [Intellisense not working with kwargs](https://discourse.julialang.org/t/intellisense-not-working-with-kwargs/120808)

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**Author:** [@Farouk](https://discourse.julialang.org/u/Farouk)\
**Replies:** 0\
**Last updated:** [October 2, 2024, 10:09am UTC](https://discourse.julialang.org/t/intellisense-not-working-with-kwargs/120808 "2024-10-02T10:09:50Z")

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Hi everyone, I am using VS Code (windows 10) with the Julia extension, however I have a problem with code auto completion. As you can see in the first image, when I enter the positional arguments IntelliSense works fine …

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## [Trying to understand low performance compared to C++](https://discourse.julialang.org/t/trying-to-understand-low-performance-compared-to-c/120804)

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**Author:** [@paulmelis](https://discourse.julialang.org/u/paulmelis)\
**Replies:** 13\
**Last updated:** [October 2, 2024, 1:19pm UTC](https://discourse.julialang.org/t/trying-to-understand-low-performance-compared-to-c/120804 "2024-10-02T13:19:46Z")

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With the toy problem below of approximating Pi by sampling a square I get an almost 4x lower performance with Julia than wit the C++ version. The code is very simple, just two nested 2 loops, no indexing, no type instabi…

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## [Flux: combine two neural networks to run simultaneously?](https://discourse.julialang.org/t/flux-combine-two-neural-networks-to-run-simultaneously/120776)

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**Author:** [@greatpet](https://discourse.julialang.org/u/greatpet)\
**Replies:** 4\
**Last updated:** [October 2, 2024, 12:21pm UTC](https://discourse.julialang.org/t/flux-combine-two-neural-networks-to-run-simultaneously/120776 "2024-10-02T12:21:34Z")

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For example, I have an input which is a length-10 vector. I want the first neural network to output a length-3 vector based on the first 5 elements of the input, and the second neural network to output a length-4 vector …

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## [Encouraging adoption story](https://discourse.julialang.org/t/encouraging-adoption-story/119098)

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**Author:** [@ElOceanografo](https://discourse.julialang.org/u/ElOceanografo)\
**Replies:** 16\
**Last updated:** [October 2, 2024, 11:53am UTC](https://discourse.julialang.org/t/encouraging-adoption-story/119098 "2024-10-02T11:53:49Z")

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I see posts on here occasionally that lament the slow uptake of Julia in the wide world, resistance from colleagues/employers, etc., and wanted to share an encouraging interaction I had recently. The story starts six ye…

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## [Can I register a package without doing unit tests? If it only has three functions and is meant to be simple](https://discourse.julialang.org/t/can-i-register-a-package-without-doing-unit-tests-if-it-only-has-three-functions-and-is-meant-to-be-simple/120803)

<div class="topic-metadata">

**Author:** [@sumant28](https://discourse.julialang.org/u/sumant28)\
**Replies:** 4\
**Last updated:** [October 2, 2024, 11:31am UTC](https://discourse.julialang.org/t/can-i-register-a-package-without-doing-unit-tests-if-it-only-has-three-functions-and-is-meant-to-be-simple/120803 "2024-10-02T11:31:05Z")

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I am trying to register this package GitHub - sumant-28/AppleHealthParser.jl I don’t have a software background so unit tests have always been foreign to me. Do I test this by adding a Monte Carlo function to my main so…

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## [Cases for using Downloads.Downloader()](https://discourse.julialang.org/t/cases-for-using-downloads-downloader/120806)

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**Author:** [@Ju\_ska](https://discourse.julialang.org/u/Ju_ska)\
**Replies:** 0\
**Last updated:** [October 2, 2024, 9:31am UTC](https://discourse.julialang.org/t/cases-for-using-downloads-downloader/120806 "2024-10-02T09:31:26Z")

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Hi, from Downloads · The Julia Language I wonder what are the benefits of using downloader = Downloads.Downloader() apart having more options. For instance, would it be useful if I download multiple files from the sa…

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## [Optimization question](https://discourse.julialang.org/t/optimization-question/120707)

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**Author:** [@lancejnelson](https://discourse.julialang.org/u/lancejnelson)\
**Replies:** 31\
**Last updated:** [October 1, 2024, 10:14pm UTC](https://discourse.julialang.org/t/optimization-question/120707 "2024-10-01T22:14:05Z")

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I’m trying to optimize the code block below: using Distributions order = 2 σ\_Priors = Array{Distribution,2}(undef,order,order) ϵ\_Priors = Array{Distribution,2}(undef,order,order) σ\_Priors\[:,:\] .= Gamma(10,0.1) ϵ\_Priors\[…

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## [Issue with SciMLSensitivity and DifferentialEquations](https://discourse.julialang.org/t/issue-with-scimlsensitivity-and-differentialequations/119796)

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**Author:** [@Nick1](https://discourse.julialang.org/u/Nick1)\
**Replies:** 10\
**Last updated:** [October 1, 2024, 10:43pm UTC](https://discourse.julialang.org/t/issue-with-scimlsensitivity-and-differentialequations/119796 "2024-10-01T22:43:37Z")

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I installed the SciMLSensitivity library and it removed the BoundaryValueDiffEq, so when I am trying to load the DifferentialEquations package, I get the following error: ERROR: LoadError: Failed to precompile Boundary…

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## [Benders Subproblem Infeasibility](https://discourse.julialang.org/t/benders-subproblem-infeasibility/102622)

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**Author:** [@bcoulier](https://discourse.julialang.org/u/bcoulier)\
**Replies:** 6\
**Last updated:** [October 1, 2024, 9:46pm UTC](https://discourse.julialang.org/t/benders-subproblem-infeasibility/102622 "2024-10-01T21:46:49Z")

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Hello everyone, I’m currently working on an optimization problem where I’m using Benders decomposition to determine the placement of EV charging stations. The master problem determines the placement of charging stations…

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## [Semiconductor laser simulation at WIAS Berlin](https://discourse.julialang.org/t/semiconductor-laser-simulation-at-wias-berlin/119544)

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**Author:** [@j-fu](https://discourse.julialang.org/u/j-fu)\
**Replies:** 1\
**Last updated:** [October 1, 2024, 8:50pm UTC](https://discourse.julialang.org/t/semiconductor-laser-simulation-at-wias-berlin/119544 "2024-10-01T20:50:04Z")

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2 Year Postdoc on Simulation of Photonic Crystal Surface Emitting Semiconductor Lasers at Weierstrass Institute, Berlin: see Research Assistant position (f/m/d) (Ref. 24/19) bei Weierstraß-Institut für Angewandte Analys…

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## [Community string benchmark suite](https://discourse.julialang.org/t/community-string-benchmark-suite/120771)

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**Author:** [@tecosaur](https://discourse.julialang.org/u/tecosaur)\
**Replies:** 3\
**Last updated:** [October 1, 2024, 7:27pm UTC](https://discourse.julialang.org/t/community-string-benchmark-suite/120771 "2024-10-01T19:27:37Z")

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Hello! I’d like your help formulating a high-quality suite of string benchmarks. Over in Internals & Design I’ve started a conversation about potentially renovating String’s memory representation to reduce memory usage …

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## [Use ⟹ instead of &&?](https://discourse.julialang.org/t/use-instead-of/120729)

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**Author:** [@Sariel](https://discourse.julialang.org/u/Sariel)\
**Replies:** 12\
**Last updated:** [October 1, 2024, 6:00pm UTC](https://discourse.julialang.org/t/use-instead-of/120729 "2024-10-01T18:00:03Z")

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I find the && notation a bit weird for shortening ifs - it works, but it feels like a hack. A nicer format might be: (condition) ⟹ do\_something It would be cool if there is a way to already define \\implies to do so, bu…

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## [Fast evaluation of linear/bilinear expressions and Jacobians from strings](https://discourse.julialang.org/t/fast-evaluation-of-linear-bilinear-expressions-and-jacobians-from-strings/120721)

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**Author:** [@Olegg](https://discourse.julialang.org/u/Olegg)\
**Replies:** 1\
**Last updated:** [October 1, 2024, 5:33pm UTC](https://discourse.julialang.org/t/fast-evaluation-of-linear-bilinear-expressions-and-jacobians-from-strings/120721 "2024-10-01T17:33:23Z")

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I have a set of m equality constraints with linear and/or bilinear terms, defined as strings. For example: \[ “P0\_I\_m − F1\_m − F2\_m”, “P0\_E\_m − F6\_m − F7\_m”, “P0\_dS\_m + P0\_E\_m − P0\_I\_m”, “F1\_m + F2\_m + F4\_m − F3\_m”, …

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## [Save\_positions parameter in solve's callback function](https://discourse.julialang.org/t/save-positions-parameter-in-solves-callback-function/102409)

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**Author:** [@yoshi](https://discourse.julialang.org/u/yoshi)\
**Replies:** 3\
**Last updated:** [August 3, 2023, 2:48am UTC](https://discourse.julialang.org/t/save-positions-parameter-in-solves-callback-function/102409 "2023-08-03T02:48:07Z")

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How does the save\_positions parameter in DiscreteCallback work? In the code example provided in Event Handling and Callback Functions · DifferentialEquations.jl (second example) the following discrete callbacks are writ…

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## [Throwing my own \`NotImplementedError\` to emulate abstract methods](https://discourse.julialang.org/t/throwing-my-own-notimplementederror-to-emulate-abstract-methods/97680)

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**Author:** [@zuckerruebe](https://discourse.julialang.org/u/zuckerruebe)\
**Replies:** 6\
**Last updated:** [October 1, 2024, 3:39pm UTC](https://discourse.julialang.org/t/throwing-my-own-notimplementederror-to-emulate-abstract-methods/97680 "2024-10-01T15:39:11Z")

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Hi there I want to write a piece of software that my users can extend by writing “plugins” for it. Specifically, they would provide their own types in their plugins, that the main program will then operate on. For the m…

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## [Why does GLM.jl fail to fit my logistic regression model but scikit learn and R has no issues? I think I found the reason](https://discourse.julialang.org/t/why-does-glm-jl-fail-to-fit-my-logistic-regression-model-but-scikit-learn-and-r-has-no-issues-i-think-i-found-the-reason/118553)

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**Author:** [@xiaodai](https://discourse.julialang.org/u/xiaodai)\
**Replies:** 5\
**Last updated:** [October 1, 2024, 2:43pm UTC](https://discourse.julialang.org/t/why-does-glm-jl-fail-to-fit-my-logistic-regression-model-but-scikit-learn-and-r-has-no-issues-i-think-i-found-the-reason/118553 "2024-10-01T14:43:54Z")

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I have been trying to use GLM.jl to fit some logistic regression models and the fit failed. I don’t remember the exact error message but it was something about singularity. That annoyed me for a couple of years but I ne…

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## [Problem with weight retrieval in Directed Graphs](https://discourse.julialang.org/t/problem-with-weight-retrieval-in-directed-graphs/120784)

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**Author:** [@paul20](https://discourse.julialang.org/u/paul20)\
**Replies:** 3\
**Last updated:** [October 1, 2024, 2:41pm UTC](https://discourse.julialang.org/t/problem-with-weight-retrieval-in-directed-graphs/120784 "2024-10-01T14:41:44Z")

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I’ve been using the SimpleWeightedDiGraph from the SimpleWeightedGraphs package for creating directed weighted graphs. Recently, I encountered a problem related to weight retrieval of edges. When initializing a SimpleWe…

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## [\[ANN\] DynamicExpressions.jl: Fast evaluation of runtime-generated expressions without compilation](https://discourse.julialang.org/t/ann-dynamicexpressions-jl-fast-evaluation-of-runtime-generated-expressions-without-compilation/88983)

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**Author:** [@MilesCranmer](https://discourse.julialang.org/u/MilesCranmer)\
**Replies:** 7\
**Last updated:** [October 1, 2024, 1:57pm UTC](https://discourse.julialang.org/t/ann-dynamicexpressions-jl-fast-evaluation-of-runtime-generated-expressions-without-compilation/88983 "2024-10-01T13:57:13Z")

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Need to work with a large space of symbolic expressions which are unknown at runtime, but numerically evaluate them just as quickly as if they were hard-coded? Then you need DynamicExpressions.jl! DynamicExpressions…

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## [\[ANN\] JMPReader.jl - Reader for JMP files in Julia](https://discourse.julialang.org/t/ann-jmpreader-jl-reader-for-jmp-files-in-julia/120710)

<div class="topic-metadata">

**Author:** [@jaakkor2](https://discourse.julialang.org/u/jaakkor2)\
**Replies:** 2\
**Last updated:** [October 1, 2024, 1:51pm UTC](https://discourse.julialang.org/t/ann-jmpreader-jl-reader-for-jmp-files-in-julia/120710 "2024-10-01T13:51:15Z")

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Announcing JMPReader.jl, a reader for files saved by JMP, commercial statistical software. Do you have a .jmp file and one or more of the following applies to you? You don’t have a JMP license You’re not running Win…

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## [Recompilation triggered when re-running function from module](https://discourse.julialang.org/t/recompilation-triggered-when-re-running-function-from-module/120770)

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**Author:** [@Rbthn](https://discourse.julialang.org/u/Rbthn)\
**Replies:** 5\
**Last updated:** [October 1, 2024, 1:36pm UTC](https://discourse.julialang.org/t/recompilation-triggered-when-re-running-function-from-module/120770 "2024-10-01T13:36:21Z")

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Hello! I’m relatively new to Julia and have encountered some behavior I cannot explain. In a MWE, I have a function that takes an ODEProblem and algorithm and just calls DiffEq.solve() with these arguments. function my…

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## [My system is overdetermined. Are there tools to find the culprit equation?](https://discourse.julialang.org/t/my-system-is-overdetermined-are-there-tools-to-find-the-culprit-equation/119947)

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**Author:** [@Datseris](https://discourse.julialang.org/u/Datseris)\
**Replies:** 4\
**Last updated:** [October 1, 2024, 1:29pm UTC](https://discourse.julialang.org/t/my-system-is-overdetermined-are-there-tools-to-find-the-culprit-equation/119947 "2024-10-01T13:29:57Z")

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Recently I’ve updated a very big project to the latest version of MTK. I now get this warning: ┌ Warning: Initialization system is overdetermined. 1 equations for 0 unknowns. Initialization will default to using least …

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## [Syntax highlighting for Pluto codecells](https://discourse.julialang.org/t/syntax-highlighting-for-pluto-codecells/118090)

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**Author:** [@biplab37](https://discourse.julialang.org/u/biplab37)\
**Replies:** 2\
**Last updated:** [October 1, 2024, 9:05am UTC](https://discourse.julialang.org/t/syntax-highlighting-for-pluto-codecells/118090 "2024-10-01T09:05:30Z")

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Is there a way to change the default syntax highlighting of the code cells in Pluto? Injecting Css might work with Stylus for a particular browser. But is there a nicer way to add CSS/JS which Pluto will read before lau…

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## [Latency with v1.11-rc3 REPL over SSH](https://discourse.julialang.org/t/latency-with-v1-11-rc3-repl-over-ssh/119498)

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**Author:** [@Qfl3x](https://discourse.julialang.org/u/Qfl3x)\
**Replies:** 22\
**Last updated:** [October 1, 2024, 6:40am UTC](https://discourse.julialang.org/t/latency-with-v1-11-rc3-repl-over-ssh/119498 "2024-10-01T06:40:33Z")

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I have a noticeable latency in 1.11-rc3 than in 1.10.5, when working locally it isn’t noticeable, but when using Julia through ssh it is quite noticeable. More info: It’s worst when starting the REPL and it gets smoothe…

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## [Adding uncertainty on timestep of Bayesian ODE solve through \`saveat\`](https://discourse.julialang.org/t/adding-uncertainty-on-timestep-of-bayesian-ode-solve-through-saveat/120424)

<div class="topic-metadata">

**Author:** [@japhir](https://discourse.julialang.org/u/japhir)\
**Replies:** 9\
**Last updated:** [October 1, 2024, 5:11am UTC](https://discourse.julialang.org/t/adding-uncertainty-on-timestep-of-bayesian-ode-solve-through-saveat/120424 "2024-10-01T05:11:17Z")

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I’d like to do a Bayesian inversion of parameters to an ODE model. I would like to add some uncertainty on the input time series. Is there any way to do this? I’ve tried to add a parameter tau ~ Uniform(-60, 60) and used…

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## [CheckGradient In Manopt.jl](https://discourse.julialang.org/t/checkgradient-in-manopt-jl/120743)

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**Author:** [@fimiller](https://discourse.julialang.org/u/fimiller)\
**Replies:** 0\
**Last updated:** [September 30, 2024, 11:25pm UTC](https://discourse.julialang.org/t/checkgradient-in-manopt-jl/120743 "2024-09-30T23:25:08Z")

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I am performing an optimization problem and wish to make sure that the gradient I have is correct. When using the check\_gradient function, I find that the gradient is only correct some of the time, (about 90% of the tim…

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## [Easy drawing of basic geometric objects: SimpleDrawingObjects](https://discourse.julialang.org/t/easy-drawing-of-basic-geometric-objects-simpledrawingobjects/120741)

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**Author:** [@scheinerman](https://discourse.julialang.org/u/scheinerman)\
**Replies:** 0\
**Last updated:** [September 30, 2024, 9:14pm UTC](https://discourse.julialang.org/t/easy-drawing-of-basic-geometric-objects-simpledrawingobjects/120741 "2024-09-30T21:14:35Z")

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There are full-featured, sophisticated Julia packages for plotting and visualization. Personally, I have found them to be so rich that they are difficult to learn and use (for me). To make drawing easier, I wrote SimpleD…

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