# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=11

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

**Page:** 12

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## [Double sum over two identical variables](https://discourse.julialang.org/t/double-sum-over-two-identical-variables/135703)

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**Author:** [@Saki](https://discourse.julialang.org/u/Saki)\
**Replies:** 3\
**Last updated:** [February 17, 2026, 10:39pm UTC](https://discourse.julialang.org/t/double-sum-over-two-identical-variables/135703 "2026-02-17T22:39:06Z")

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I am trying to implement a mathematical model in JuMP but cant seem to figure out how i should write this constraint because i needs to be in both A and P @constraint(m, \[(i,j) in data.A, i in data.P\], sum(xs\[(i, j), …

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## [ODE Parameter Estimation with Priors](https://discourse.julialang.org/t/ode-parameter-estimation-with-priors/135691)

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**Author:** [@donkeysaddle](https://discourse.julialang.org/u/donkeysaddle)\
**Replies:** 2\
**Last updated:** [February 17, 2026, 5:54pm UTC](https://discourse.julialang.org/t/ode-parameter-estimation-with-priors/135691 "2026-02-17T17:54:42Z")

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I have never done parameter estimation with priors(bayesian inference) before and I am a little unsure if I am going about it the right way. I created a simple example, but will ultimately be doing it for a more complica…

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## [(JuMP) Best way to implement sequential convex (or quadratic) programming](https://discourse.julialang.org/t/jump-best-way-to-implement-sequential-convex-or-quadratic-programming/135669)

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**Author:** [@jackyarndley](https://discourse.julialang.org/u/jackyarndley)\
**Replies:** 4\
**Last updated:** [February 17, 2026, 2:43am UTC](https://discourse.julialang.org/t/jump-best-way-to-implement-sequential-convex-or-quadratic-programming/135669 "2026-02-17T02:43:39Z")

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Hi all, I work with sequential convex programming (SCP) for trajectory optimization, which is where a nonlinear programming problem is approximated by a sequence of convex linearizations. The structure of the problem do…

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## [Zero copy conversion of FixedPointArrays to base types without specialization](https://discourse.julialang.org/t/zero-copy-conversion-of-fixedpointarrays-to-base-types-without-specialization/135668)

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**Author:** [@csvance](https://discourse.julialang.org/u/csvance)\
**Replies:** 3\
**Last updated:** [February 16, 2026, 10:47pm UTC](https://discourse.julialang.org/t/zero-copy-conversion-of-fixedpointarrays-to-base-types-without-specialization/135668 "2026-02-16T22:47:09Z")

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I mostly work with obscure image formats like lossless JPEG, but recently I needed ImageIO to load some other types of images for a training data pipeline. It seems to return images with fixed point types, and all of my …

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## [How to narrow the variants of agents returned by \`random\_agent\`?](https://discourse.julialang.org/t/how-to-narrow-the-variants-of-agents-returned-by-random-agent/135674)

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**Author:** [@filipe](https://discourse.julialang.org/u/filipe)\
**Replies:** 11\
**Last updated:** [February 16, 2026, 8:14pm UTC](https://discourse.julialang.org/t/how-to-narrow-the-variants-of-agents-returned-by-random-agent/135674 "2026-02-16T20:14:03Z")

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Hello! Is there a way to tell random\_agent which variant of a @multiagent model to return? My specific problem is this: @agent struct Supplier(NoSpaceAgent) sellingPrice::Float64 = 1 end @agent struct Buyer(NoSpac…

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## [How to define pre-compile workloads for Makie figures in a module?](https://discourse.julialang.org/t/how-to-define-pre-compile-workloads-for-makie-figures-in-a-module/135683)

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**Author:** [@RoyW](https://discourse.julialang.org/u/RoyW)\
**Replies:** 1\
**Last updated:** [February 16, 2026, 7:11pm UTC](https://discourse.julialang.org/t/how-to-define-pre-compile-workloads-for-makie-figures-in-a-module/135683 "2026-02-16T19:11:58Z")

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I modified the interactive button counting example from the official Makie documentation. It has a mouse-hover and button-click interactive events. May someone please help me with the pre-compilation workload code? I wo…

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## [Different initial conditions / trajectories when updating parameters with setp+remake vs re-solving steady state (ModelingToolkit ODEProblem)](https://discourse.julialang.org/t/different-initial-conditions-trajectories-when-updating-parameters-with-setp-remake-vs-re-solving-steady-state-modelingtoolkit-odeproblem/135676)

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**Author:** [@celia.bat](https://discourse.julialang.org/u/celia.bat)\
**Replies:** 2\
**Last updated:** [February 16, 2026, 4:20pm UTC](https://discourse.julialang.org/t/different-initial-conditions-trajectories-when-updating-parameters-with-setp-remake-vs-re-solving-steady-state-modelingtoolkit-odeproblem/135676 "2026-02-16T16:20:50Z")

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Hi all, I’m confused about how remake interacts with initialization / consistent initial conditions in a ModelingToolkit workflow where I: Solve a “static” system using a SteadyStateProblem to get an equilibrium. Use …

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## [How to make Makie themes work with plots inside loops?](https://discourse.julialang.org/t/how-to-make-makie-themes-work-with-plots-inside-loops/135666)

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**Author:** [@CosmoProf](https://discourse.julialang.org/u/CosmoProf)\
**Replies:** 2\
**Last updated:** [February 15, 2026, 11:29pm UTC](https://discourse.julialang.org/t/how-to-make-makie-themes-work-with-plots-inside-loops/135666 "2026-02-15T23:29:09Z")

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Hi again, another unusual question about getting Makie themes to work. I need plot elements to keep getting added to a big plot inside a loop, but then the Makie “with\_themes” command doesn’t work anymore. For example, I…

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## [Band in CairoMakie makes whole plot black](https://discourse.julialang.org/t/band-in-cairomakie-makes-whole-plot-black/135656)

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**Author:** [@phma](https://discourse.julialang.org/u/phma)\
**Replies:** 1\
**Last updated:** [February 15, 2026, 6:38pm UTC](https://discourse.julialang.org/t/band-in-cairomakie-makes-whole-plot-black/135656 "2026-02-15T18:38:25Z")

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function plotSmallSlices(allDiffs::smallDict,key::String,bytes::Integer) # one round, as more would look like noise sl=Figure(size=(1189,841)) slax=Axis3(sl\[1,1\], title=(@sprintf "Wring differential cryptanal…

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## [FreeType.jl Color emoji support, review wanted](https://discourse.julialang.org/t/freetype-jl-color-emoji-support-review-wanted/135658)

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**Author:** [@ErikBuer](https://discourse.julialang.org/u/ErikBuer)\
**Replies:** 0\
**Last updated:** [February 15, 2026, 12:25pm UTC](https://discourse.julialang.org/t/freetype-jl-color-emoji-support-review-wanted/135658 "2026-02-15T12:25:08Z")

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Hi everyone. I’m not sure if this is the correct platform, but i’m wondering if anyone part of Julia Graphics would have the time to look at my FreeType.jl Emoji PR? It adds necessary bindings to implement color emojis…

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## [LsqFit example](https://discourse.julialang.org/t/lsqfit-example/135621)

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**Author:** [@Jake](https://discourse.julialang.org/u/Jake)\
**Replies:** 1\
**Last updated:** [February 13, 2026, 6:19pm UTC](https://discourse.julialang.org/t/lsqfit-example/135621 "2026-02-13T18:19:49Z")

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I am working through the initial example in GitHub - JuliaNLSolvers/LsqFit.jl: Simple curve fitting in Julia and don’t know where the function model comes from. julia\> using LsqFit julia\> xdata = range(0, stop=10, leng…

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## [Linearising an nonlinear, algebraic DAE for MPC control](https://discourse.julialang.org/t/linearising-an-nonlinear-algebraic-dae-for-mpc-control/135151)

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**Author:** [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Replies:** 5\
**Last updated:** [February 13, 2026, 5:30pm UTC](https://discourse.julialang.org/t/linearising-an-nonlinear-algebraic-dae-for-mpc-control/135151 "2026-02-13T17:30:55Z")

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We have the idea that we might be able to use linear MPC to control kites modelled as differential-algebraic equations using MTK. I have a student who has some issues with linearizing: It is easy to linearize a system a…

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## [On a minimalistic interface for DifferentialEquations.jl](https://discourse.julialang.org/t/on-a-minimalistic-interface-for-differentialequations-jl/135575)

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**Author:** [@Bizzi](https://discourse.julialang.org/u/Bizzi)\
**Replies:** 3\
**Last updated:** [February 12, 2026, 1:48pm UTC](https://discourse.julialang.org/t/on-a-minimalistic-interface-for-differentialequations-jl/135575 "2026-02-12T13:48:24Z")

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I, like most people here, think that DifferentialEquations.jl is a truly fantastic package and one of the major reasons to use Julia over other langs. Still, I’ve found that it is often very bulky: instead of returning a…

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## [Any package for plots in style of Scientific Journals?](https://discourse.julialang.org/t/any-package-for-plots-in-style-of-scientific-journals/135378)

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**Author:** [@CosmoProf](https://discourse.julialang.org/u/CosmoProf)\
**Replies:** 33\
**Last updated:** [February 12, 2026, 7:59am UTC](https://discourse.julialang.org/t/any-package-for-plots-in-style-of-scientific-journals/135378 "2026-02-12T07:59:37Z")

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Hi, I am preparing plots for submission to a professional scientific journal (specifically, The Astrophysical Journal). Are there any Julia packages designed to make the plots look appropriate for the style of a journal …

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## [SDMX parser](https://discourse.julialang.org/t/sdmx-parser/61143)

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**Author:** [@gr\_julia](https://discourse.julialang.org/u/gr_julia)\
**Replies:** 2\
**Last updated:** [February 12, 2026, 2:59am UTC](https://discourse.julialang.org/t/sdmx-parser/61143 "2026-02-12T02:59:02Z")

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Hi all, I’m new to Julia and trying to automate data retrieval. That’s fairly easy for JSON formats but many organisations now use SDMX-ML. I could not find a parser though (and have no idea how to write one). Has anyon…

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## [ModelingToolkit.jl: Handling Output/Input Dependency in a DAE Model](https://discourse.julialang.org/t/modelingtoolkit-jl-handling-output-input-dependency-in-a-dae-model/126172)

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**Author:** [@AndhikaTama](https://discourse.julialang.org/u/AndhikaTama)\
**Replies:** 4\
**Last updated:** [February 11, 2026, 4:46am UTC](https://discourse.julialang.org/t/modelingtoolkit-jl-handling-output-input-dependency-in-a-dae-model/126172 "2026-02-11T04:46:00Z")

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Hello everyone, I’m currently working on a dynamic of microgas turbine system model in Julia using a system of Differential-Algebraic Equations (DAE). I want to adapt modelica acausal modelling problem into Julia …

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## [\`data\[i, "γ (N/m)"\] ~ Normal(γ\_pred, σ)\` disallowed in Turing.jl in v0.42? how to fix?](https://discourse.julialang.org/t/data-i-n-m-normal-pred-disallowed-in-turing-jl-in-v0-42-how-to-fix/135438)

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**Author:** [@Cory\_Simon](https://discourse.julialang.org/u/Cory_Simon)\
**Replies:** 2\
**Last updated:** [February 9, 2026, 7:51pm UTC](https://discourse.julialang.org/t/data-i-n-m-normal-pred-disallowed-in-turing-jl-in-v0-42-how-to-fix/135438 "2026-02-09T19:51:38Z")

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a Turing.jl breaking changes question: I updated ↑ Turing v0.41.1 ⇒ v0.42.8, then my code broke. is data\[i, "γ (N/m)"\] ~ Normal(γ\_pred, σ) disallowed now? see code and error below. I looked for breaking changes in 0.4…

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## [Problems with complex values in optimization objective (JuMP)](https://discourse.julialang.org/t/problems-with-complex-values-in-optimization-objective-jump/135504)

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**Author:** [@dnldlg](https://discourse.julialang.org/u/dnldlg)\
**Replies:** 5\
**Last updated:** [February 9, 2026, 12:35am UTC](https://discourse.julialang.org/t/problems-with-complex-values-in-optimization-objective-jump/135504 "2026-02-09T00:35:33Z")

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When using complex valued numbers in the objective function, get an error that I struggle to understand. This minimal example illustrates it very well. Let’s say we want to find parameters of a parametrised unitay matrix…

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## [Is there a reason to use \`@expression\`? I think it's redundant](https://discourse.julialang.org/t/is-there-a-reason-to-use-expression-i-think-its-redundant/131829)

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**Author:** [@WalterMadelim](https://discourse.julialang.org/u/WalterMadelim)\
**Replies:** 14\
**Last updated:** [February 8, 2026, 1:04am UTC](https://discourse.julialang.org/t/is-there-a-reason-to-use-expression-i-think-its-redundant/131829 "2026-02-08T01:04:58Z")

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Sometimes I build incorrect expressions obliviously, but JuMP won’t throw an ERROR. Is this good? import JuMP, Gurobi model1 = JuMP.Model(Gurobi.Optimizer); JuMP.@variable(model1, x1 \>= 1); JuMP.@objective(model1, Min, …

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## [Issue adding Julia package from GitHub: Unsatisfiable requirements (SymbolicUtils / SciCompDSL / ModelingToolkit)](https://discourse.julialang.org/t/issue-adding-julia-package-from-github-unsatisfiable-requirements-symbolicutils-scicompdsl-modelingtoolkit/135334)

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**Author:** [@pandeysudan27](https://discourse.julialang.org/u/pandeysudan27)\
**Replies:** 6\
**Last updated:** [February 7, 2026, 12:11am UTC](https://discourse.julialang.org/t/issue-adding-julia-package-from-github-unsatisfiable-requirements-symbolicutils-scicompdsl-modelingtoolkit/135334 "2026-02-07T00:11:47Z")

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Unsatisfiable requirements when adding package from GitHub (SymbolicUtils / SciCompDSL / MTK) Hi everyone, I’m developing a Julia package for acausal hydropower system modeling based on ModelingToolkit.jl and ModelingT…

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## [Dynamic optimization over a step function in MTK and InfiniteOpt](https://discourse.julialang.org/t/dynamic-optimization-over-a-step-function-in-mtk-and-infiniteopt/135496)

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**Author:** [@cstjean](https://discourse.julialang.org/u/cstjean)\
**Replies:** 1\
**Last updated:** [February 6, 2026, 3:07pm UTC](https://discourse.julialang.org/t/dynamic-optimization-over-a-step-function-in-mtk-and-infiniteopt/135496 "2026-02-06T15:07:00Z")

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After watching the inspiring Optimal Control in Julia: SciML’s newest tooling | Rackauckas | Paris 2025, I’d like to use the dynamic optimization interface. While InfiniteOpt is made to work with “infinite parameters”, c…

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## [Floating-point accuracy visualization example: the ULP error for each math function coming with Julia](https://discourse.julialang.org/t/floating-point-accuracy-visualization-example-the-ulp-error-for-each-math-function-coming-with-julia/135392)

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**Author:** [@nsajko](https://discourse.julialang.org/u/nsajko)\
**Replies:** 20\
**Last updated:** [February 6, 2026, 2:25pm UTC](https://discourse.julialang.org/t/floating-point-accuracy-visualization-example-the-ulp-error-for-each-math-function-coming-with-julia/135392 "2026-02-06T14:25:29Z")

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Introduction The implementation of a math function, such as cos(::Float64) in Julia, should be fast, but also needs to be at least somewhat accurate. Here I propose a method for visualizing empirical accuracy data. Cons…

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## [Simulating a disconnected line](https://discourse.julialang.org/t/simulating-a-disconnected-line/135324)

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**Author:** [@Magnus\_Lilledahl](https://discourse.julialang.org/u/Magnus_Lilledahl)\
**Replies:** 2\
**Last updated:** [February 6, 2026, 1:48pm UTC](https://discourse.julialang.org/t/simulating-a-disconnected-line/135324 "2026-02-06T13:48:40Z")

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In pandapower it is possible to set a line parameter “in\_service” to false and the model will still run with all connected loads set to zero. I tried to set “br\_status” to 0 in powermodels but then the model returns infe…

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## [HiGHS (via JuMP) decides MIP solution to be infeasible](https://discourse.julialang.org/t/highs-via-jump-decides-mip-solution-to-be-infeasible/135421)

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**Author:** [@asprionj](https://discourse.julialang.org/u/asprionj)\
**Replies:** 13\
**Last updated:** [February 6, 2026, 9:41am UTC](https://discourse.julialang.org/t/highs-via-jump-decides-mip-solution-to-be-infeasible/135421 "2026-02-06T09:41:08Z")

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As part of an optimisation-based control algorithm I solve a series of equally structured problems that only differ by the numerical values. For some “random” instances, I get output such as the following: MIP has 7 row…

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## [Sigma-clip function?](https://discourse.julialang.org/t/sigma-clip-function/88228)

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**Author:** [@mkretlow](https://discourse.julialang.org/u/mkretlow)\
**Replies:** 2\
**Last updated:** [February 5, 2026, 2:59pm UTC](https://discourse.julialang.org/t/sigma-clip-function/88228 "2026-02-05T14:59:29Z")

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Before I re-invent the wheel… Do a sigma-clip function exist (similar to scipy.stats.sigmaclip) in some Julia package, preferable which works also on DataFrames !?

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## [Convert symbolic expression to floating point?](https://discourse.julialang.org/t/convert-symbolic-expression-to-floating-point/107788)

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**Author:** [@Krastanov](https://discourse.julialang.org/u/Krastanov)\
**Replies:** 2\
**Last updated:** [February 5, 2026, 12:05pm UTC](https://discourse.julialang.org/t/convert-symbolic-expression-to-floating-point/107788 "2026-02-05T12:05:55Z")

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This is about Symbolics.jl I have a variableless symbolic expression wrap(Term(sqrt, \[2\])) as a way to represent an irrational constant symbolically. But at some point I want to actually compute the floating point value…

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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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