# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=12

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**Page:** 13

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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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## [Gaussian Copula Priors in Turing: Auto-differentiation Error with Beta Quantile Function](https://discourse.julialang.org/t/gaussian-copula-priors-in-turing-auto-differentiation-error-with-beta-quantile-function/132779)

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**Author:** [@giovannitinervia9](https://discourse.julialang.org/u/giovannitinervia9)\
**Replies:** 7\
**Last updated:** [January 26, 2026, 1:16pm UTC](https://discourse.julialang.org/t/gaussian-copula-priors-in-turing-auto-differentiation-error-with-beta-quantile-function/132779 "2026-01-26T13:16:37Z")

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I’m trying to fit a Bayesian model in Turing that uses Gaussian copula priors for parameters bounded in (0, 1). The baseline model with independent priors works fine, but when I introduce copula-based correlations, I enc…

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## [Singular BVP with integrable boundaries](https://discourse.julialang.org/t/singular-bvp-with-integrable-boundaries/135224)

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**Author:** [@NoFishLikeIan](https://discourse.julialang.org/u/NoFishLikeIan)\
**Replies:** 2\
**Last updated:** [January 26, 2026, 7:13am UTC](https://discourse.julialang.org/t/singular-bvp-with-integrable-boundaries/135224 "2026-01-26T07:13:46Z")

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I’m solving a singular first-order, two dimensional ODE arising in reputation games (Faingold & Sannikov, 2011). On \\phi \\in \[0, 1\], I have u' = \\frac{v}{\\phi(1-\\phi)} \\\\ v' = \\frac{1}{\\phi(1-\\phi)} \\left(v + 2\\rho \\f…

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## [How to create a standalone \`JuMP.Containers.SparseAxisArray{Float64, n, Tuple{Int, ...}}\`?](https://discourse.julialang.org/t/how-to-create-a-standalone-jump-containers-sparseaxisarray-float64-n-tuple-int/135253)

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**Author:** [@WalterMadelim](https://discourse.julialang.org/u/WalterMadelim)\
**Replies:** 2\
**Last updated:** [January 26, 2026, 12:02am UTC](https://discourse.julialang.org/t/how-to-create-a-standalone-jump-containers-sparseaxisarray-float64-n-tuple-int/135253 "2026-01-26T00:02:02Z")

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I’m interested in the X per se, as a container of a set of Float64 numbers (not depending on some JuMP variable x built beforehand). julia\> import JuMP, Gurobi julia\> model = JuMP.direct\_model(Gurobi.Optimizer()); jul…

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## [Saving GLMakie figure without widgets](https://discourse.julialang.org/t/saving-glmakie-figure-without-widgets/135258)

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**Author:** [@AdamWysokinski](https://discourse.julialang.org/u/AdamWysokinski)\
**Replies:** 2\
**Last updated:** [January 25, 2026, 9:42pm UTC](https://discourse.julialang.org/t/saving-glmakie-figure-without-widgets/135258 "2026-01-25T21:42:00Z")

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Hi, Is there any way to save GLMakie figure without buttons/sliders? MWE: p = Figure(size=(500, 500)) ax = Axis(p\[1, 1\]) b = Button(p\[2, 1\], label="button", tellwidth=false) GLMakie.scatter!(1, 1) GLMakie.save("test.p…

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