# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?page=13

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

**Page:** 14

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## [HTTP/3 and QUIC protocols, status of for Julia web clients or servers](https://discourse.julialang.org/t/http-3-and-quic-protocols-status-of-for-julia-web-clients-or-servers/78473)

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**Author:** [@Palli](https://discourse.julialang.org/u/Palli)\
**Replies:** 9\
**Last updated:** [February 4, 2026, 9:13pm UTC](https://discourse.julialang.org/t/http-3-and-quic-protocols-status-of-for-julia-web-clients-or-servers/78473 "2026-02-04T21:13:20Z")

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HTTP/3 seems to be around the corner, already implemented in most web browsers (may be off by default), makes web browsing much faster. It’s based on QUIC protocal (which IS DONE), then UDP, not TCP of TCP/IP (so it’s go…

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## [MTK - Any models of electrical machines?](https://discourse.julialang.org/t/mtk-any-models-of-electrical-machines/135446)

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**Author:** [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Replies:** 1\
**Last updated:** [February 4, 2026, 2:23pm UTC](https://discourse.julialang.org/t/mtk-any-models-of-electrical-machines/135446 "2026-02-04T14:23:51Z")

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Are there any models of electrical machines already available that are programmed using MTK? I am looking for: DC machine asynchronous machine synchronous machine two-speed Dahlander motor

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## [MTK & library components - good practice?](https://discourse.julialang.org/t/mtk-library-components-good-practice/135448)

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**Author:** [@BLI](https://discourse.julialang.org/u/BLI)\
**Replies:** 0\
**Last updated:** [February 4, 2026, 1:36pm UTC](https://discourse.julialang.org/t/mtk-library-components-good-practice/135448 "2026-02-04T13:36:46Z")

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I’m curious: what is good practice with MTK components which uses Stream variables/has multiple substances? How to ensure that the various components are created/instantiated with equal number of substances, so that I …

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## [MTK -- status of symbolic vectors?](https://discourse.julialang.org/t/mtk-status-of-symbolic-vectors/135150)

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**Author:** [@BLI](https://discourse.julialang.org/u/BLI)\
**Replies:** 12\
**Last updated:** [February 4, 2026, 11:52am UTC](https://discourse.julialang.org/t/mtk-status-of-symbolic-vectors/135150 "2026-02-04T11:52:35Z")

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What is the status of MTK and vectors of symbolic variables? I am working my way through connectors and components, aided by Google AI Studio, but I have a feeling it is hallucinating some proposals…

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## [Help with setting up coupled PDE system for adsorption column](https://discourse.julialang.org/t/help-with-setting-up-coupled-pde-system-for-adsorption-column/130751)

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**Author:** [@shisac](https://discourse.julialang.org/u/shisac)\
**Replies:** 9\
**Last updated:** [February 4, 2026, 7:53am UTC](https://discourse.julialang.org/t/help-with-setting-up-coupled-pde-system-for-adsorption-column/130751 "2026-02-04T07:53:19Z")

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Hi all, I’m trying to model an adsorption column with a system of PDEs, which have been discretized in space using a WENO finite volume scheme. I’m new to julia and this is my first time simulating a complex system like…

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## [Solving optimization problems involving orthogonal matrices](https://discourse.julialang.org/t/solving-optimization-problems-involving-orthogonal-matrices/135431)

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**Author:** [@HMegh](https://discourse.julialang.org/u/HMegh)\
**Replies:** 4\
**Last updated:** [February 3, 2026, 7:13pm UTC](https://discourse.julialang.org/t/solving-optimization-problems-involving-orthogonal-matrices/135431 "2026-02-03T19:13:20Z")

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I am working on an optimization problem on the set of orthogonal matrices O\_n=\\{A \\text{ is } n\\times n \\text{ and }AA^T=I\_n\\}. Basically, it is a minimization problem of the form \\min\_{(A,\\mathbf{x})\\in O\_n\\times \\mat…

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## [Error in conversion pipeline. xs and ys should have size ni+1, nj+1](https://discourse.julialang.org/t/error-in-conversion-pipeline-xs-and-ys-should-have-size-ni-1-nj-1/102372)

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**Author:** [@CosmicSpittle](https://discourse.julialang.org/u/CosmicSpittle)\
**Replies:** 3\
**Last updated:** [February 3, 2026, 3:36pm UTC](https://discourse.julialang.org/t/error-in-conversion-pipeline-xs-and-ys-should-have-size-ni-1-nj-1/102372 "2026-02-03T15:36:44Z")

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Hi - Can someone tell me what this error means? Error in conversion pipeline. xs and ys should have size ni+1, nj+1. I am trying to create a spectrogram heatmap in CairoMakie. I’ve created some test data (called test)…

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## [Parameter sensitivity of ODE with parameter-dependent event](https://discourse.julialang.org/t/parameter-sensitivity-of-ode-with-parameter-dependent-event/103602)

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**Author:** [@Neodym](https://discourse.julialang.org/u/Neodym)\
**Replies:** 4\
**Last updated:** [February 2, 2026, 11:28am UTC](https://discourse.julialang.org/t/parameter-sensitivity-of-ode-with-parameter-dependent-event/103602 "2026-02-02T11:28:17Z")

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Hey, I’m trying to get parameter sensitivities of an ODE problem with a parameter-dependent time-event. Just throwing AD at the problem doesn’t seem to work: using OrdinaryDiffEq using SciMLSensitivity using ForwardDi…

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## [Callbacks are skipped in various settings](https://discourse.julialang.org/t/callbacks-are-skipped-in-various-settings/135293)

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**Author:** [@sceptri](https://discourse.julialang.org/u/sceptri)\
**Replies:** 2\
**Last updated:** [February 2, 2026, 10:59am UTC](https://discourse.julialang.org/t/callbacks-are-skipped-in-various-settings/135293 "2026-02-02T10:59:58Z")

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Hello! I am working on simulations related to spiking neuron networks (with discontinuous models, like LIF, and possible delays), and I have run into several problems with callbacks in DifferentialEquations.jl. I opene…

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## [Paper on the accuracy of math functions](https://discourse.julialang.org/t/paper-on-the-accuracy-of-math-functions/132227)

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**Author:** [@JeffreySarnoff](https://discourse.julialang.org/u/JeffreySarnoff)\
**Replies:** 1\
**Last updated:** [February 1, 2026, 9:04pm UTC](https://discourse.julialang.org/t/paper-on-the-accuracy-of-math-functions/132227 "2026-02-01T21:04:20Z")

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Mantas Mikaitis and Tejaswa Rizyal have this well developed, reliable paper The software is available on github:

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## [Concave parameteric surface mesh generation](https://discourse.julialang.org/t/concave-parameteric-surface-mesh-generation/135375)

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**Author:** [@Avina-cK](https://discourse.julialang.org/u/Avina-cK)\
**Replies:** 2\
**Last updated:** [February 1, 2026, 3:54pm UTC](https://discourse.julialang.org/t/concave-parameteric-surface-mesh-generation/135375 "2026-02-01T15:54:10Z")

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I would like to generate a surface mesh, using a parametric function f(x,y,z) = (x-(z^2))^2 + y^2 + z^2-1. Generating points and creating a vertex list is not an issue. How would I create a proper topology, to then crea…

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## [Direct collocation, stiff dynamics, and discrete adjoints — where does the instability go?](https://discourse.julialang.org/t/direct-collocation-stiff-dynamics-and-discrete-adjoints-where-does-the-instability-go/135385)

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**Author:** [@PhysicsBender](https://discourse.julialang.org/u/PhysicsBender)\
**Replies:** 3\
**Last updated:** [February 1, 2026, 1:33pm UTC](https://discourse.julialang.org/t/direct-collocation-stiff-dynamics-and-discrete-adjoints-where-does-the-instability-go/135385 "2026-02-01T13:33:00Z")

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Hi all, I’ve been experimenting with ModelingToolkit.jl and InfiniteOpt.jl for direct-collocation optimal control problems. In my model I am using smooth boolean logic that is based on hyperbolic functions quite extensi…

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## [Show significance on boxplots](https://discourse.julialang.org/t/show-significance-on-boxplots/77365)

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**Author:** [@jewh](https://discourse.julialang.org/u/jewh)\
**Replies:** 18\
**Last updated:** [January 31, 2026, 10:32am UTC](https://discourse.julialang.org/t/show-significance-on-boxplots/77365 "2026-01-31T10:32:34Z")

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I want to annotate the statistical significance of the difference between a pair of boxplots on my figure, as one of 'n.s.', '\*', '\*\*', '\*\*\*'. An example image of what I want is below, the best analogue I can find of wha…

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## [Savefig causes a flash on the display](https://discourse.julialang.org/t/savefig-causes-a-flash-on-the-display/56647)

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**Author:** [@LeePhillips](https://discourse.julialang.org/u/LeePhillips)\
**Replies:** 2\
**Last updated:** [January 30, 2026, 8:46pm UTC](https://discourse.julialang.org/t/savefig-causes-a-flash-on-the-display/56647 "2026-01-30T20:46:02Z")

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Calling savefig(“file”) writes the file, and the plots are as expected. But every call causes the screen to flash. I believe the plot is momentarily displayed and the plot window removed before the file is written. Runni…

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## [How to trace positions of agents](https://discourse.julialang.org/t/how-to-trace-positions-of-agents/135340)

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**Author:** [@ahcvankampen](https://discourse.julialang.org/u/ahcvankampen)\
**Replies:** 5\
**Last updated:** [January 30, 2026, 12:23pm UTC](https://discourse.julialang.org/t/how-to-trace-positions-of-agents/135340 "2026-01-30T12:23:39Z")

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Hi, I have a multiagent model and want to extract agent data from this model. In one of the tutorial examples we have something like: adata = \[(cd4, count), (cd8, count), (dc, count)\] fig, ax, abmobs = abmplot(ln\_mode…

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## [How to run a Julia package using Visual Studio Code?](https://discourse.julialang.org/t/how-to-run-a-julia-package-using-visual-studio-code/135338)

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**Author:** [@xulongxu](https://discourse.julialang.org/u/xulongxu)\
**Replies:** 3\
**Last updated:** [January 30, 2026, 11:31am UTC](https://discourse.julialang.org/t/how-to-run-a-julia-package-using-visual-studio-code/135338 "2026-01-30T11:31:58Z")

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I am reading the article - “Quasinormal mode/grey-body factor correspondence for Kerr black holes”, which use the the following pacakge to compute the the QNM frequencies of the fundamental mode and the first overto…

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## [Parameter sharing and abstraction in MTK](https://discourse.julialang.org/t/parameter-sharing-and-abstraction-in-mtk/135269)

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**Author:** [@cstjean](https://discourse.julialang.org/u/cstjean)\
**Replies:** 3\
**Last updated:** [January 30, 2026, 9:26am UTC](https://discourse.julialang.org/t/parameter-sharing-and-abstraction-in-mtk/135269 "2026-01-30T09:26:27Z")

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I have started using ParametrizedInterpolation from the standard library in my code, and while it works fine, having to add a clock to each component that uses it tarnishes the code a bit. So I wrote this: """ A step fu…

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## [\[ANN\] PortfolioOptimisers.jl](https://discourse.julialang.org/t/ann-portfoliooptimisers-jl/135325)

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**Author:** [@dcelisgarza](https://discourse.julialang.org/u/dcelisgarza)\
**Replies:** 0\
**Last updated:** [January 29, 2026, 4:26pm UTC](https://discourse.julialang.org/t/ann-portfoliooptimisers-jl/135325 "2026-01-29T16:26:05Z")

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PortfolioOptimisers.jl I noticed Julia there was no comprehensive portfolio optimisation package, so I made one. It has a huge number of features, many of them composable, so the world is your oyster. I’m still actively…

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## [Flexible linear constraints for MPC and codegen](https://discourse.julialang.org/t/flexible-linear-constraints-for-mpc-and-codegen/135285)

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**Author:** [@franckgaga](https://discourse.julialang.org/u/franckgaga)\
**Replies:** 10\
**Last updated:** [January 29, 2026, 4:19pm UTC](https://discourse.julialang.org/t/flexible-linear-constraints-for-mpc-and-codegen/135285 "2026-01-29T16:19:39Z")

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Following the subject \[ANN\] ModelPredictiveControl.jl with @langestefan and @darnstrom: The expressiveness of the linear MPC framework is already very limited and the current syntax limits it further. As long as my exp…

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## [Plots.jl: QPaintDevice: Cannot destroy paint device that is being painted \[SOLVED\]](https://discourse.julialang.org/t/plots-jl-qpaintdevice-cannot-destroy-paint-device-that-is-being-painted-solved/135323)

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**Author:** [@ericsfraga](https://discourse.julialang.org/u/ericsfraga)\
**Replies:** 1\
**Last updated:** [January 29, 2026, 1:46pm UTC](https://discourse.julialang.org/t/plots-jl-qpaintdevice-cannot-destroy-paint-device-that-is-being-painted-solved/135323 "2026-01-29T13:46:15Z")

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Good morning. Anybody here using the Plots.jl package for Julia? I am trying to generate some plots in files without having them display on the screen. I have a sequence of plt = plot(...) plot!(plt, ...) plot!(plt, ...…

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## [Force MTK to generate explicit ODEs?](https://discourse.julialang.org/t/force-mtk-to-generate-explicit-odes/135245)

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**Author:** [@benjamin](https://discourse.julialang.org/u/benjamin)\
**Replies:** 9\
**Last updated:** [January 29, 2026, 1:30pm UTC](https://discourse.julialang.org/t/force-mtk-to-generate-explicit-odes/135245 "2026-01-29T13:30:05Z")

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Hi! I am using ModelingToolkit.jl to model a physical system. The compiler generates an index-1 DAE, which works great for simulation. However, I need to use a standard Kalman Filter, which requires a minimal state-spa…

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## [Stokes solver as an ODEproblem takes time to initiate](https://discourse.julialang.org/t/stokes-solver-as-an-odeproblem-takes-time-to-initiate/135317)

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**Author:** [@Iddingsite](https://discourse.julialang.org/u/Iddingsite)\
**Replies:** 6\
**Last updated:** [January 29, 2026, 10:15am UTC](https://discourse.julialang.org/t/stokes-solver-as-an-odeproblem-takes-time-to-initiate/135317 "2026-01-29T10:15:42Z")

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Hi everyone. I wrote a small code to solve 2D linear visco-elastic Stokes using finite difference and OrdinaryDiffEq to test how that would work out. So, in this case, I only have algebraic equations and have some param…

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## [Sometimes no objective\_bound info from an LP solve, by Gurobi](https://discourse.julialang.org/t/sometimes-no-objective-bound-info-from-an-lp-solve-by-gurobi/135080)

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**Author:** [@WalterMadelim](https://discourse.julialang.org/u/WalterMadelim)\
**Replies:** 13\
**Last updated:** [January 29, 2026, 7:35am UTC](https://discourse.julialang.org/t/sometimes-no-objective-bound-info-from-an-lp-solve-by-gurobi/135080 "2026-01-29T07:35:35Z")

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I solved an LP by Gurobi using Non-default parameters: Method 6 Crossover 0 PDHGGPU 1 And here’s the result julia\> model A JuMP Model ├ mode: DIRECT ├ solver: Gurobi ├ objective\_sense: MIN\_SENSE │ └ objective\_funct…

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## [Best way to forcibly passify a result using ForwardDiff?](https://discourse.julialang.org/t/best-way-to-forcibly-passify-a-result-using-forwarddiff/135283)

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**Author:** [@afleming](https://discourse.julialang.org/u/afleming)\
**Replies:** 3\
**Last updated:** [January 28, 2026, 10:30am UTC](https://discourse.julialang.org/t/best-way-to-forcibly-passify-a-result-using-forwarddiff/135283 "2026-01-28T10:30:33Z")

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I’m working on the implementation of a time-stepping method and would like to force that part of the computation always be a passive value (in the AD sense). The function in question is a simple broadcasted computation,…

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## [Eigen value and eigen functions of linear operator](https://discourse.julialang.org/t/eigen-value-and-eigen-functions-of-linear-operator/133859)

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**Author:** [@Liris](https://discourse.julialang.org/u/Liris)\
**Replies:** 19\
**Last updated:** [January 28, 2026, 9:20am UTC](https://discourse.julialang.org/t/eigen-value-and-eigen-functions-of-linear-operator/133859 "2026-01-28T09:20:20Z")

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I am doing the linear stability analysis of a system of equations representing a free surface flow, which typically ends up with a generalised eigenvalue problem of the form: L\_{1} X = \\lambda p(z) u L\_{2} X = \\lambda …

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## [Debugging Container of Constraints in JuMP](https://discourse.julialang.org/t/debugging-container-of-constraints-in-jump/122509)

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**Author:** [@lamont](https://discourse.julialang.org/u/lamont)\
**Replies:** 9\
**Last updated:** [January 28, 2026, 7:56am UTC](https://discourse.julialang.org/t/debugging-container-of-constraints-in-jump/122509 "2026-01-28T07:56:50Z")

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I’m trying to debug a container of constraints built using the vectorized linear algebra syntax and trying to go in through the MOI interface to check the constraint value based on the start\_value of the variables. I’ve…

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## [Catalyst.jl and ModelingToolkit (question after reading about ModelingToolkit license changes)](https://discourse.julialang.org/t/catalyst-jl-and-modelingtoolkit-question-after-reading-about-modelingtoolkit-license-changes/135303)

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**Author:** [@twcawm](https://discourse.julialang.org/u/twcawm)\
**Replies:** 1\
**Last updated:** [January 28, 2026, 4:06am UTC](https://discourse.julialang.org/t/catalyst-jl-and-modelingtoolkit-question-after-reading-about-modelingtoolkit-license-changes/135303 "2026-01-28T04:06:51Z")

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Hi, I have been investigating and trying out the Catalyst.jl package (it’s really awesome, by the way!). I saw recently the discussions on ModelingToolkit license changes. Is the plan to keep maintaining Catalyst.jl a…

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## [\[ANN\] Casacore.jl - routines for radio astronomy](https://discourse.julialang.org/t/ann-casacore-jl-routines-for-radio-astronomy/89590)

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**Author:** [@torrance](https://discourse.julialang.org/u/torrance)\
**Replies:** 6\
**Last updated:** [January 27, 2026, 10:51pm UTC](https://discourse.julialang.org/t/ann-casacore-jl-routines-for-radio-astronomy/89590 "2026-01-27T22:51:23Z")

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I’m excited to announce the first public release of Casacore.jl - a high-level Julia wrapper for the popular C++ (radio) astronomy package Casacore. This first release of Casacore.jl focuses on exposing Casacore.Tables …

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## [Stokes Operator is Singular After Applying Dirichlet Boundary Conditions](https://discourse.julialang.org/t/stokes-operator-is-singular-after-applying-dirichlet-boundary-conditions/135278)

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**Author:** [@noetheriankoala](https://discourse.julialang.org/u/noetheriankoala)\
**Replies:** 7\
**Last updated:** [January 27, 2026, 5:53pm UTC](https://discourse.julialang.org/t/stokes-operator-is-singular-after-applying-dirichlet-boundary-conditions/135278 "2026-01-27T17:53:11Z")

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Hello! I am trying to implement a simple incompressible Navier-Stokes simulation. I have a mesh consisting of a cylinder with the Stanford bunny excised from its center. When I apply Drichlet boundary conditions, the Sto…

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## [Increase margin of combined plot made out of subplots with Plots.jl](https://discourse.julialang.org/t/increase-margin-of-combined-plot-made-out-of-subplots-with-plots-jl/135270)

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**Author:** [@Fourier](https://discourse.julialang.org/u/Fourier)\
**Replies:** 2\
**Last updated:** [January 26, 2026, 2:23pm UTC](https://discourse.julialang.org/t/increase-margin-of-combined-plot-made-out-of-subplots-with-plots-jl/135270 "2026-01-26T14:23:00Z")

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I am plotting multiple plots in a combined plot like this: using Plots using Plots.Measures: mm plots = Vector{Any}() for (i,j) in Iterators.product(1:4, 1:4) p = scatter(rand(100), xlabel="X-axis $i,$j", ylabel="Y…

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