# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=21

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**Page:** 22

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## [Optimization with AD of complex struct-based architecture](https://discourse.julialang.org/t/optimization-with-ad-of-complex-struct-based-architecture/133436)

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**Author:** [@stevenhughes](https://discourse.julialang.org/u/stevenhughes)\
**Replies:** 3\
**Last updated:** [October 27, 2025, 7:44am UTC](https://discourse.julialang.org/t/optimization-with-ad-of-complex-struct-based-architecture/133436 "2025-10-27T07:44:15Z")

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Hi everyone, I’m working on adding automatic differentiation to an optimization framework and running into some fundamental architectural issues. The framework uses a Directed Acyclic Graph modeled after Fig. 7 in this …

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## [Solving SemilinearODE without using automatic differentiation](https://discourse.julialang.org/t/solving-semilinearode-without-using-automatic-differentiation/133434)

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**Author:** [@sanjeev](https://discourse.julialang.org/u/sanjeev)\
**Replies:** 4\
**Last updated:** [October 27, 2025, 2:10am UTC](https://discourse.julialang.org/t/solving-semilinearode-without-using-automatic-differentiation/133434 "2025-10-27T02:10:13Z")

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I have semilinear ODE with the time-dependent linear implicit part as function f1! So, instead of solving (I - γΔt \* J₁) \* u\_{n+1} = rhs, I want to use Krylov method to solve (I - γΔt \* J1) \* u\_{n+1} = rhs, where J1 \* u…

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## [Export makie figure object to file](https://discourse.julialang.org/t/export-makie-figure-object-to-file/84160)

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**Author:** [@Thomberger](https://discourse.julialang.org/u/Thomberger)\
**Replies:** 4\
**Last updated:** [October 26, 2025, 3:30pm UTC](https://discourse.julialang.org/t/export-makie-figure-object-to-file/84160 "2025-10-26T15:30:03Z")

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Is it possible to export a makie figure to a file, so later i can just load the file to recreate the figure and do not need to import my data, make all the computation required and finally plot it again ? I don’t want t…

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## [ModelingToolKit and the number pi](https://discourse.julialang.org/t/modelingtoolkit-and-the-number-pi/132543)

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**Author:** [@ziolai](https://discourse.julialang.org/u/ziolai)\
**Replies:** 5\
**Last updated:** [October 26, 2025, 9:44am UTC](https://discourse.julialang.org/t/modelingtoolkit-and-the-number-pi/132543 "2025-10-26T09:44:37Z")

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I am likely misunderstanding the issue below. The issues, however, of ModelingToolkit not liking pi reported previously at Discretization of semi-coupled wave and diffusion equations fails for step size of pi/(25n) usin…

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## [Status of geodesy packages in Julia (DGGS experiments)](https://discourse.julialang.org/t/status-of-geodesy-packages-in-julia-dggs-experiments/133379)

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**Author:** [@allixender](https://discourse.julialang.org/u/allixender)\
**Replies:** 12\
**Last updated:** [October 25, 2025, 10:27am UTC](https://discourse.julialang.org/t/status-of-geodesy-packages-in-julia-dggs-experiments/133379 "2025-10-25T10:27:13Z")

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Hi all, I would like to instigate a short review discussion on geodesy-related packages in Julia. My background is GIS, geospatial, and recently Discrete Global Grid Systems (DGGS) in particular. If you have heard of Ub…

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## [Understanding and optimizing Enzyme.jl Reverse AD on CUDA](https://discourse.julialang.org/t/understanding-and-optimizing-enzyme-jl-reverse-ad-on-cuda/133357)

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**Author:** [@Riccardo\_Buscicchio](https://discourse.julialang.org/u/Riccardo_Buscicchio)\
**Replies:** 5\
**Last updated:** [October 25, 2025, 7:36am UTC](https://discourse.julialang.org/t/understanding-and-optimizing-enzyme-jl-reverse-ad-on-cuda/133357 "2025-10-25T07:36:54Z")

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Hi all, we are working on a nested sampling algorithm whose proposals are assisted by HMC, and we want to leverage Enzyme.jl to autodiff our loglikelihood kernel. We have a MWE on a simple 4D gaussian likelihood (4 par…

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## [Julia crashes without reporting anything when I optimize a vector of models in parallel](https://discourse.julialang.org/t/julia-crashes-without-reporting-anything-when-i-optimize-a-vector-of-models-in-parallel/131801)

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**Author:** [@WalterMadelim](https://discourse.julialang.org/u/WalterMadelim)\
**Replies:** 22\
**Last updated:** [October 25, 2025, 1:55am UTC](https://discourse.julialang.org/t/julia-crashes-without-reporting-anything-when-i-optimize-a-vector-of-models-in-parallel/131801 "2025-10-25T01:55:47Z")

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My setting is julia\> Threads.nthreads() 4 I can’t figure out what is happening here. The behavior is julia\> parallel\_CG!(B, θ, β, μ, ν) ┌ Info: before entering @threads │ sub\_j\_vec = │ 4-element Vector{Int64}: │ …

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## [Modeling Toolkit with ∇c · ∇Φ\_2 Term](https://discourse.julialang.org/t/modeling-toolkit-with-c-2-term/133180)

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**Author:** [@nickbrady](https://discourse.julialang.org/u/nickbrady)\
**Replies:** 4\
**Last updated:** [October 24, 2025, 10:44pm UTC](https://discourse.julialang.org/t/modeling-toolkit-with-c-2-term/133180 "2025-10-24T22:44:38Z")

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I am trying to solve a system of PDE in the ModelingToolkit. I can solve the unsteady heat equation for multiple species and for Neumann and Dirichlet boundary conditions, see MWE. However, I am looking to solve more co…

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## [Graphviz running but not printing](https://discourse.julialang.org/t/graphviz-running-but-not-printing/133394)

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**Author:** [@aidanpetro1](https://discourse.julialang.org/u/aidanpetro1)\
**Replies:** 4\
**Last updated:** [October 24, 2025, 7:26pm UTC](https://discourse.julialang.org/t/graphviz-running-but-not-printing/133394 "2025-10-24T19:26:40Z")

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Hey, I’m trying to run the code below in VS code. I have graphviz installed and have the Julia graphviz pkg installed as well. The code runs without errors besides the graphviz part which gives the below error. using C…

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## [Issue using ModelingToolkit to simulate electrical circuits](https://discourse.julialang.org/t/issue-using-modelingtoolkit-to-simulate-electrical-circuits/133415)

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**Author:** [@JaviJR](https://discourse.julialang.org/u/JaviJR)\
**Replies:** 7\
**Last updated:** [October 24, 2025, 5:40pm UTC](https://discourse.julialang.org/t/issue-using-modelingtoolkit-to-simulate-electrical-circuits/133415 "2025-10-24T17:40:28Z")

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Hello everyone, Lately, I have been working quite extensively with ModelingToolkit, particularly migrating some dynamic control models that I had previously implemented in various closed-source programs (often achieving…

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## [Is it possible to use structural\_parameters as an argument of \`System\` in ModelingToolkit?](https://discourse.julialang.org/t/is-it-possible-to-use-structural-parameters-as-an-argument-of-system-in-modelingtoolkit/133396)

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**Author:** [@pmc4](https://discourse.julialang.org/u/pmc4)\
**Replies:** 6\
**Last updated:** [October 24, 2025, 4:15pm UTC](https://discourse.julialang.org/t/is-it-possible-to-use-structural-parameters-as-an-argument-of-system-in-modelingtoolkit/133396 "2025-10-24T16:15:21Z")

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Hello everyone. When building a model in ModelingToolkit, there is the option of doing it with the macro @mtkmodel. Inside the macro, we can define structural parameters for defining numerical variables. For example, co…

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## [Method Error when using Method of Lines to solve PDEs](https://discourse.julialang.org/t/method-error-when-using-method-of-lines-to-solve-pdes/132951)

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**Author:** [@gst1017](https://discourse.julialang.org/u/gst1017)\
**Replies:** 3\
**Last updated:** [October 24, 2025, 3:52pm UTC](https://discourse.julialang.org/t/method-error-when-using-method-of-lines-to-solve-pdes/132951 "2025-10-24T15:52:53Z")

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Hello all! I’m new to Julia and am trying to use the Method of Lines and MTK packages to solve a system of PDEs. I am running into repeated method errors, and the stacktrace keeps pointing to a line from Macro Expanded c…

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## [How to properly set aspect for Axis defined in multiple fig positions in Makie](https://discourse.julialang.org/t/how-to-properly-set-aspect-for-axis-defined-in-multiple-fig-positions-in-makie/133216)

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**Author:** [@albertomercurio](https://discourse.julialang.org/u/albertomercurio)\
**Replies:** 7\
**Last updated:** [October 24, 2025, 1:38pm UTC](https://discourse.julialang.org/t/how-to-properly-set-aspect-for-axis-defined-in-multiple-fig-positions-in-makie/133216 "2025-10-24T13:38:33Z")

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Hello, I have the following figure structure fig = Figure() ax1 = Axis(fig\[1,1\]) ax2 = Axis(fig\[1,2\]) ax3 = Axis(fig\[2,1\]) ax4 = Axis(fig\[2,2\]) ax5 = Axis(fig\[1:2,3\]) colsize!(fig.layout, 3, Relative(0.6)) fig where…

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## [Problems when replacing Flux by Lux in anodes example](https://discourse.julialang.org/t/problems-when-replacing-flux-by-lux-in-anodes-example/133120)

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**Author:** [@Jaime\_Araneda](https://discourse.julialang.org/u/Jaime_Araneda)\
**Replies:** 1\
**Last updated:** [October 24, 2025, 1:19pm UTC](https://discourse.julialang.org/t/problems-when-replacing-flux-by-lux-in-anodes-example/133120 "2025-10-24T13:19:21Z")

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Hello, I’m trying to reproduce the anodes example on augmented neural ODEs from the thread Fitting neural ODE to periodic time series. However, when replacing Flux by the Lux library (with the corresponding changes) I g…

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## [How to ignore minibatches with NaN gradients optimizing a hybrid LUX model using Optimization.jl](https://discourse.julialang.org/t/how-to-ignore-minibatches-with-nan-gradients-optimizing-a-hybrid-lux-model-using-optimization-jl/132615)

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**Author:** [@progtw1](https://discourse.julialang.org/u/progtw1)\
**Replies:** 1\
**Last updated:** [October 24, 2025, 1:17pm UTC](https://discourse.julialang.org/t/how-to-ignore-minibatches-with-nan-gradients-optimizing-a-hybrid-lux-model-using-optimization-jl/132615 "2025-10-24T13:17:45Z")

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I try following the LUX tutorial on fitting an ML model using Optimization.jl for fitting a hybrid model, where the LUX model predicts some parameters of a process-based model, the LUX model application is just a call in…

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## [Best options for Graph Neural Network integration with Flux](https://discourse.julialang.org/t/best-options-for-graph-neural-network-integration-with-flux/133368)

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**Author:** [@AriMarkowitz](https://discourse.julialang.org/u/AriMarkowitz)\
**Replies:** 5\
**Last updated:** [October 24, 2025, 7:15am UTC](https://discourse.julialang.org/t/best-options-for-graph-neural-network-integration-with-flux/133368 "2025-10-24T07:15:42Z")

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Hello! I built a library that utilizes GraphNeuralNetworks.jl and Flux.jl, but the GraphNeuralNetworks.jl tests are currently failing in Julia 1.12 (and the same failure is causing my custom library to crash when used).…

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## [Beginning with PEtab, only one entry per measurement?](https://discourse.julialang.org/t/beginning-with-petab-only-one-entry-per-measurement/133388)

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**Author:** [@kraqbi](https://discourse.julialang.org/u/kraqbi)\
**Replies:** 0\
**Last updated:** [October 23, 2025, 2:11pm UTC](https://discourse.julialang.org/t/beginning-with-petab-only-one-entry-per-measurement/133388 "2025-10-23T14:11:20Z")

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Hello, I try PEtab for the first time and I am studying the documentation and tutorial of PEtab. I was wondering, the DataFrame I create, is it absolutely necessary to have just one entry per measurement? There is no b…

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## [Is it possible to add legends with Makie recepies?](https://discourse.julialang.org/t/is-it-possible-to-add-legends-with-makie-recepies/133375)

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**Author:** [@ohmsweetohm1](https://discourse.julialang.org/u/ohmsweetohm1)\
**Replies:** 1\
**Last updated:** [October 23, 2025, 8:51am UTC](https://discourse.julialang.org/t/is-it-possible-to-add-legends-with-makie-recepies/133375 "2025-10-23T08:51:42Z")

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I have a Makie.@recipe for a custom type. When creating the plot, I also supply labels to the plot elements such as line!. However, when I call Legend on the axis where the plot is, Makie complaints that there are no lab…

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## [Efficiently Retrieving Variable Values after Gurobi optimization with JuMP](https://discourse.julialang.org/t/efficiently-retrieving-variable-values-after-gurobi-optimization-with-jump/127049)

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**Author:** [@Mathis\_3](https://discourse.julialang.org/u/Mathis_3)\
**Replies:** 29\
**Last updated:** [October 23, 2025, 4:45am UTC](https://discourse.julialang.org/t/efficiently-retrieving-variable-values-after-gurobi-optimization-with-jump/127049 "2025-10-23T04:45:19Z")

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Hello, I’m solving a large number of LPs using Gurobi with JuMP, and I noticed that most of the computation time is spent retrieving variable values rather than optimizing the model. Is there a more efficient way to ext…

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## [Help reformulating nonlinear problem](https://discourse.julialang.org/t/help-reformulating-nonlinear-problem/133292)

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**Author:** [@chensunn](https://discourse.julialang.org/u/chensunn)\
**Replies:** 2\
**Last updated:** [October 22, 2025, 8:57pm UTC](https://discourse.julialang.org/t/help-reformulating-nonlinear-problem/133292 "2025-10-22T20:57:29Z")

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I have a nonlinear problem that I wish to solve with Ipopt and derive gradients with DiffOpt.jl. Unfortunately, I’m running into problems with the gradients from DiffOpt. I suspect that I might be able to resolve those i…

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## [Kolmogorov-Smirnov test](https://discourse.julialang.org/t/kolmogorov-smirnov-test/89990)

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**Author:** [@GHTaarn](https://discourse.julialang.org/u/GHTaarn)\
**Replies:** 23\
**Last updated:** [October 22, 2025, 6:46pm UTC](https://discourse.julialang.org/t/kolmogorov-smirnov-test/89990 "2025-10-22T18:46:20Z")

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I have a sample consisting of a set of integers and want to test if can be from a specific distribution. I am not that strong in statistics, but my understanding is that the Kolmogorov-Smirnov test is a good choice for a…

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## [HiGHS solver \>100x slower than Gurobi with bilinear big-m relaxation](https://discourse.julialang.org/t/highs-solver-100x-slower-than-gurobi-with-bilinear-big-m-relaxation/114905)

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**Author:** [@this\_josh](https://discourse.julialang.org/u/this_josh)\
**Replies:** 3\
**Last updated:** [October 22, 2025, 6:24pm UTC](https://discourse.julialang.org/t/highs-solver-100x-slower-than-gurobi-with-bilinear-big-m-relaxation/114905 "2025-10-22T18:24:08Z")

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I’m not sure where to put this as it’s not specifically an issue, and I’m not sure who would improve it. For my research I need to solve a bilinear model and I’d like to use an open-source solver ideally. ▶ Rough exampl…

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## [Package for Multivariate (normal) Conditional Distribution](https://discourse.julialang.org/t/package-for-multivariate-normal-conditional-distribution/112765)

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**Author:** [@PharmCat](https://discourse.julialang.org/u/PharmCat)\
**Replies:** 2\
**Last updated:** [October 22, 2025, 2:23pm UTC](https://discourse.julialang.org/t/package-for-multivariate-normal-conditional-distribution/112765 "2025-10-22T14:23:59Z")

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Hi! Is any package to get Multivariate (normal) Conditional Distribution? Something like described here.

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## [Issubset gives error for this Hexahedron](https://discourse.julialang.org/t/issubset-gives-error-for-this-hexahedron/133346)

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**Author:** [@raman\_kumar](https://discourse.julialang.org/u/raman_kumar)\
**Replies:** 2\
**Last updated:** [October 22, 2025, 1:07pm UTC](https://discourse.julialang.org/t/issubset-gives-error-for-this-hexahedron/133346 "2025-10-22T13:07:12Z")

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In this code m ⊆ m2 should output either true or false. using Meshes m = Hexahedron((0.1547376288700546, 0.05921552849426126, 1.7379087983473205), (0.17193069874450512, 0.05921552849426126, 1.7379087983473205), (0.1719…

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## [Interpolated parameters into the PDESystems](https://discourse.julialang.org/t/interpolated-parameters-into-the-pdesystems/132736)

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**Author:** [@sraghuram](https://discourse.julialang.org/u/sraghuram)\
**Replies:** 6\
**Last updated:** [October 22, 2025, 12:47pm UTC](https://discourse.julialang.org/t/interpolated-parameters-into-the-pdesystems/132736 "2025-10-22T12:47:42Z")

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Hey I am trying to solve a system of equations where my input parameters are altitude dependent values. These values should be supplied into system of equations after discretizing the equation. I have created an Interpol…

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## [Negative loss when doing parameter estimation of ODEs](https://discourse.julialang.org/t/negative-loss-when-doing-parameter-estimation-of-odes/133299)

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**Author:** [@macquarrielucas](https://discourse.julialang.org/u/macquarrielucas)\
**Replies:** 7\
**Last updated:** [October 22, 2025, 9:10am UTC](https://discourse.julialang.org/t/negative-loss-when-doing-parameter-estimation-of-odes/133299 "2025-10-22T09:10:41Z")

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When doing parameter estimation of ODEs using the optim package I’m seeing negative losses returned by the optimizer. I set up a simple example which reproduces it, and I can’t see anything strange I’m doing that might …

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## [Fastest way to access individual frames from .avi video?](https://discourse.julialang.org/t/fastest-way-to-access-individual-frames-from-avi-video/133339)

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**Author:** [@mastrof](https://discourse.julialang.org/u/mastrof)\
**Replies:** 3\
**Last updated:** [October 22, 2025, 2:42am UTC](https://discourse.julialang.org/t/fastest-way-to-access-individual-frames-from-avi-video/133339 "2025-10-22T02:42:20Z")

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I have a collection of relatively large videos (~10k frames), and I need to perform some operation on each of these frames, independently. In an ideal world I would have each frame as a separate tiff, but these are .avi…

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## [JuMP reports an error when attempting to sum the empty DenseAxisArray as the objective function](https://discourse.julialang.org/t/jump-reports-an-error-when-attempting-to-sum-the-empty-denseaxisarray-as-the-objective-function/133332)

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**Author:** [@karei](https://discourse.julialang.org/u/karei)\
**Replies:** 7\
**Last updated:** [October 22, 2025, 1:15am UTC](https://discourse.julialang.org/t/jump-reports-an-error-when-attempting-to-sum-the-empty-denseaxisarray-as-the-objective-function/133332 "2025-10-22T01:15:57Z")

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Minimal Reproducible Example using JuMP set = Symbol\[\] m = Model() @variable(m, x\[i in set\]) @objective(m, Min, sum(x; init=0)) In this case, optimization is not impossible; rather, an unexpected error occurs when the …

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## [Catalyst.jl - model reaction network with changing parameters during drug dosing](https://discourse.julialang.org/t/catalyst-jl-model-reaction-network-with-changing-parameters-during-drug-dosing/133340)

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**Author:** [@Mindy](https://discourse.julialang.org/u/Mindy)\
**Replies:** 2\
**Last updated:** [October 21, 2025, 6:14pm UTC](https://discourse.julialang.org/t/catalyst-jl-model-reaction-network-with-changing-parameters-during-drug-dosing/133340 "2025-10-21T18:14:25Z")

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Hi, I am trying to implement a infusion dosing with my reaction network. The infusion rate will be changing depending on the time. If during the infusion duration, there’s a value for k\_inf, otherwise it will be 0. and t…

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## [Visual connection between different axes in Makie.jl](https://discourse.julialang.org/t/visual-connection-between-different-axes-in-makie-jl/116535)

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**Author:** [@albertomercurio](https://discourse.julialang.org/u/albertomercurio)\
**Replies:** 11\
**Last updated:** [October 21, 2025, 3:10pm UTC](https://discourse.julialang.org/t/visual-connection-between-different-axes-in-makie-jl/116535 "2025-10-21T15:10:54Z")

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Hello, I have a figure generated with CairoMakie.jl. This figure contains two axes, something like fig = Figure(size=(380, 220)) ax1 = Axis(fig\[1, 1\]) ax2 = Axis(fig\[2, 1\]) Now, I want to draw some lines (or even …

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