# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=30

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

**Page:** 31

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## [An idea to explain a drastic difference in computation times for optimizing a JuMP model, and the unexpected ranking of solvers used?](https://discourse.julialang.org/t/an-idea-to-explain-a-drastic-difference-in-computation-times-for-optimizing-a-jump-model-and-the-unexpected-ranking-of-solvers-used/131253)

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**Author:** [@XavierG](https://discourse.julialang.org/u/XavierG)\
**Replies:** 8\
**Last updated:** [August 6, 2025, 11:47pm UTC](https://discourse.julialang.org/t/an-idea-to-explain-a-drastic-difference-in-computation-times-for-optimizing-a-jump-model-and-the-unexpected-ranking-of-solvers-used/131253 "2025-08-06T23:47:11Z")

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I have to solve a basic parametric MILP.: \\begin{equation} \\begin{split} \\mbox{maximize} & \\quad \\alpha \\\\ \\mbox{s.t.} & \\quad \\alpha \\leq - \\lambda\_j(\\psi)(r\_{\*j} - z\_j(x)), \\,\\, j=1,\\dots,d \\\\ & \\qua…

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## [Julia crashed when using Gurobi](https://discourse.julialang.org/t/julia-crashed-when-using-gurobi/131402)

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**Author:** [@Z\_M](https://discourse.julialang.org/u/Z_M)\
**Replies:** 3\
**Last updated:** [August 6, 2025, 11:45pm UTC](https://discourse.julialang.org/t/julia-crashed-when-using-gurobi/131402 "2025-08-06T23:45:12Z")

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I used JuMP and use Gurobi. But julia crashed, and the log is as follows: Please submit a bug report with steps to reproduce this fault, and any error messages that follow (in their entirety). Thanks. Exception: EXCEPT…

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## [Trinary/Ternary Variables](https://discourse.julialang.org/t/trinary-ternary-variables/87679)

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**Author:** [@chelseas](https://discourse.julialang.org/u/chelseas)\
**Replies:** 4\
**Last updated:** [August 6, 2025, 11:43pm UTC](https://discourse.julialang.org/t/trinary-ternary-variables/87679 "2025-08-06T23:43:56Z")

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I am looking to efficiently implement trinary/ternary variables in a JuMP model. I am considering the following options: An integer variable with lb=-1, ub=1 (set of values {-1,0,1}) A semi-integer variable…(can take 0…

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## [Pure-Julia Sparse Cholesky](https://discourse.julialang.org/t/pure-julia-sparse-cholesky/131293)

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**Author:** [@samuelsonric](https://discourse.julialang.org/u/samuelsonric)\
**Replies:** 31\
**Last updated:** [August 6, 2025, 10:01pm UTC](https://discourse.julialang.org/t/pure-julia-sparse-cholesky/131293 "2025-08-06T22:01:33Z")

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I implemented the Cholesky decomposition of sparse positive-definite matrices in CliqueTrees.jl. The implementation is pure-Julia, except for some calls to BLAS and LAPACK kernels. Even the column-ordering algorithm is w…

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## [New package: SimplexTableaux](https://discourse.julialang.org/t/new-package-simplextableaux/131422)

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**Author:** [@scheinerman](https://discourse.julialang.org/u/scheinerman)\
**Replies:** 0\
**Last updated:** [August 6, 2025, 7:49pm UTC](https://discourse.julialang.org/t/new-package-simplextableaux/131422 "2025-08-06T19:49:53Z")

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Primarily for educational purposes, announcing SimplexTableaux: a package for creating and working with linear programming tableaux. Users can create a tableau for a linear program, specify a basis (or have the computer …

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## [How to handle missing values in Turing.jl](https://discourse.julialang.org/t/how-to-handle-missing-values-in-turing-jl/131395)

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**Author:** [@imantha](https://discourse.julialang.org/u/imantha)\
**Replies:** 1\
**Last updated:** [August 6, 2025, 6:01pm UTC](https://discourse.julialang.org/t/how-to-handle-missing-values-in-turing-jl/131395 "2025-08-06T18:01:33Z")

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I am attempting a problem where my observed variable (tested\_positive) has missing values. I am wondering how to attempt such a problem using Turing.jl. In my cases I have popn covariates which have no missing values, t…

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## [Plot Shape by Value](https://discourse.julialang.org/t/plot-shape-by-value/131183)

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**Author:** [@ziolai](https://discourse.julialang.org/u/ziolai)\
**Replies:** 17\
**Last updated:** [August 6, 2025, 6:02pm UTC](https://discourse.julialang.org/t/plot-shape-by-value/131183 "2025-08-06T18:02:08Z")

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Greetings. I am seeking to extend using Plots p1 = \[(0., 0.), (1., 0.), (2., 0.)\]; p2 = \[(1., 0.), (2., 0.), (3., 0.)\]; p3 = \[(1., 1.), (2., 1.), (3., 1.)\]; p = Plots.plot(xlabel = "x", ylabel = "y",legend = false,a…

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## [Graphics Learning in Julia](https://discourse.julialang.org/t/graphics-learning-in-julia/131407)

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**Author:** [@raman\_kumar](https://discourse.julialang.org/u/raman_kumar)\
**Replies:** 2\
**Last updated:** [August 6, 2025, 4:04pm UTC](https://discourse.julialang.org/t/graphics-learning-in-julia/131407 "2025-08-06T16:04:40Z")

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I saw this course of Ray Tracing. I thing it would be good to have such courses in Julia. Do we have such other graphics learning resources in Julia? Please tell resources/books that you think would be good for learning …

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## [Catalyst.jl - @observables usage](https://discourse.julialang.org/t/catalyst-jl-observables-usage/131377)

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**Author:** [@Mindy](https://discourse.julialang.org/u/Mindy)\
**Replies:** 3\
**Last updated:** [August 6, 2025, 2:22pm UTC](https://discourse.julialang.org/t/catalyst-jl-observables-usage/131377 "2025-08-06T14:22:39Z")

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Hi, I have a question about using @observables inside @reaction\_network - How to write the observable contains both parameters and species? For example, what’s the correct syntax for writing Tree? function model() …

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## [Optimization-based PI controller tuning for a delay system](https://discourse.julialang.org/t/optimization-based-pi-controller-tuning-for-a-delay-system/131405)

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**Author:** [@VPBML](https://discourse.julialang.org/u/VPBML)\
**Replies:** 3\
**Last updated:** [August 6, 2025, 2:06pm UTC](https://discourse.julialang.org/t/optimization-based-pi-controller-tuning-for-a-delay-system/131405 "2025-08-06T14:06:28Z")

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Hi, I am trying to find a good tuning for a PI controler on a first-order-plus-delay system using Optimization. A naive first try combining ControlSystems.jl and Optimization.jl did not work and gave some errors. I wond…

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## [Choosing suitable options for solver ODE](https://discourse.julialang.org/t/choosing-suitable-options-for-solver-ode/77843)

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**Author:** [@Camilo\_Chaparro](https://discourse.julialang.org/u/Camilo_Chaparro)\
**Replies:** 2\
**Last updated:** [August 6, 2025, 1:28pm UTC](https://discourse.julialang.org/t/choosing-suitable-options-for-solver-ode/77843 "2025-08-06T13:28:41Z")

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Hello everyone, I want about the most suitable ODE solver for the following problem: using DifferentialEquations using Plots; plotly() #Parameters omega\_m = 1.6e6 N = 1 Delta\_mw = -0.7 …

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## [Is it possible to evaluate the objective function within the "Optimisers.apply!" function?](https://discourse.julialang.org/t/is-it-possible-to-evaluate-the-objective-function-within-the-optimisers-apply-function/130826)

<div class="topic-metadata">

**Author:** [@lorena](https://discourse.julialang.org/u/lorena)\
**Replies:** 2\
**Last updated:** [August 6, 2025, 11:35am UTC](https://discourse.julialang.org/t/is-it-possible-to-evaluate-the-objective-function-within-the-optimisers-apply-function/130826 "2025-08-06T11:35:08Z")

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I am working on implementing the MoMo method for adaptive learning rates in momentum optimizers, and it requires an evaluation of the objective function within the update rule. Until now I have been implementing my own …

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## [Deconstruct NamedTupleColumn with Prefix](https://discourse.julialang.org/t/deconstruct-namedtuplecolumn-with-prefix/131297)

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**Author:** [@mreichMPI-BGC](https://discourse.julialang.org/u/mreichMPI-BGC)\
**Replies:** 5\
**Last updated:** [August 5, 2025, 9:17pm UTC](https://discourse.julialang.org/t/deconstruct-namedtuplecolumn-with-prefix/131297 "2025-08-05T21:17:23Z")

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Similar to this one: Transform! to destructure NamedTuple into columns I’d like to do the same, but be able to programmatically prefix the "child"columns with the “parent” prefix. That is in the linked MWE, I would lik…

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## [Setting \`abstol\` and \`reltol\` when solving the Schrödinger equation with OrdinaryDiffEq](https://discourse.julialang.org/t/setting-abstol-and-reltol-when-solving-the-schrodinger-equation-with-ordinarydiffeq/125534)

<div class="topic-metadata">

**Author:** [@goerz](https://discourse.julialang.org/u/goerz)\
**Replies:** 27\
**Last updated:** [August 5, 2025, 9:10pm UTC](https://discourse.julialang.org/t/setting-abstol-and-reltol-when-solving-the-schrodinger-equation-with-ordinarydiffeq/125534 "2025-08-05T21:10:57Z")

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Note: This topic was originally title “DiffEqOrdinaryDiffEq fails to preserve norm in simple Schrödinger equation”, which was solved by setting reltol. The more interesting part of the discussion is how to set abstol and…

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## [Genie modularize @app logic](https://discourse.julialang.org/t/genie-modularize-app-logic/131373)

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**Author:** [@vh94](https://discourse.julialang.org/u/vh94)\
**Replies:** 0\
**Last updated:** [August 5, 2025, 12:40pm UTC](https://discourse.julialang.org/t/genie-modularize-app-logic/131373 "2025-08-05T12:40:21Z")

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Is there a way to programmatically initialize @in and @out vars in GenieFramework.jl ? I would like to call a type of constructor from a module sever logic using namespaces , :tree, :ghost, to not have to initialize ev…

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## [Differentiation of struct based simulations and applications](https://discourse.julialang.org/t/differentiation-of-struct-based-simulations-and-applications/131319)

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**Author:** [@stevenhughes](https://discourse.julialang.org/u/stevenhughes)\
**Replies:** 5\
**Last updated:** [August 5, 2025, 12:03pm UTC](https://discourse.julialang.org/t/differentiation-of-struct-based-simulations-and-applications/131319 "2025-08-05T12:03:54Z")

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Hello, I’m building an aerospace simulator and solver in Julia. It’s coming together well, and I plan to release the first public version in about a month. The system models spacecraft, maneuvers, events, and so on, and…

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## [Loading Lux params and states in a new script](https://discourse.julialang.org/t/loading-lux-params-and-states-in-a-new-script/131370)

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**Author:** [@imantha](https://discourse.julialang.org/u/imantha)\
**Replies:** 1\
**Last updated:** [August 5, 2025, 11:49am UTC](https://discourse.julialang.org/t/loading-lux-params-and-states-in-a-new-script/131370 "2025-08-05T11:49:29Z")

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To save a model the Training a Simple Lstm tutorial shows the following using JDL2 package # train.jl using JLD2 @save "trained\_model.jld2" ps\_trained st\_trained @load "trained\_model.jld2" ps\_trained st\_trained But th…

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## [Issue with recreating MTK problems](https://discourse.julialang.org/t/issue-with-recreating-mtk-problems/131344)

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**Author:** [@VPBML](https://discourse.julialang.org/u/VPBML)\
**Replies:** 4\
**Last updated:** [August 5, 2025, 8:45am UTC](https://discourse.julialang.org/t/issue-with-recreating-mtk-problems/131344 "2025-08-05T08:45:00Z")

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Hi, I am playing with a simple system consisting of a first-order dynamics and a PI-controller. The goal is to find a good tuning of the controller using optimization, with Integral Square Error as the objective functio…

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## [Why doesn't 1//0 throw an error?](https://discourse.julialang.org/t/why-doesnt-1-0-throw-an-error/131354)

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**Author:** [@HMegh](https://discourse.julialang.org/u/HMegh)\
**Replies:** 5\
**Last updated:** [August 5, 2025, 4:21am UTC](https://discourse.julialang.org/t/why-doesnt-1-0-throw-an-error/131354 "2025-08-05T04:21:30Z")

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Hi, I have noticed that 1//0 does not throw any errors, which is a bit unexpected. Even more, inv(0//1) is 1//0. On the other hand, 0//0 throws an argument error (understandably). Is this the intended behavior? My cur…

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## [How to use Lux.apply for a composite model](https://discourse.julialang.org/t/how-to-use-lux-apply-for-a-composite-model/131331)

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**Author:** [@imantha](https://discourse.julialang.org/u/imantha)\
**Replies:** 1\
**Last updated:** [August 5, 2025, 12:44am UTC](https://discourse.julialang.org/t/how-to-use-lux-apply-for-a-composite-model/131331 "2025-08-05T00:44:07Z")

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I am following the CVAE tutorial in Lux (Convolutional VAE for MNIST using Reactant | Lux.jl Docs) to construct a VAE . Everything was all good till I came to the loss function which looks like this function loss\_funct…

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## [\`IOStream\` buffering pitfalls when communicating to a device file](https://discourse.julialang.org/t/iostream-buffering-pitfalls-when-communicating-to-a-device-file/130071)

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**Author:** [@Yuan-Ru-Lin](https://discourse.julialang.org/u/Yuan-Ru-Lin)\
**Replies:** 1\
**Last updated:** [August 4, 2025, 9:26pm UTC](https://discourse.julialang.org/t/iostream-buffering-pitfalls-when-communicating-to-a-device-file/130071 "2025-08-04T21:26:32Z")

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I was talking to an ADS1115 ADC over I²C via /dev/i2c-1 on a Raspberry Pi 4. My first attempt was using high-level IOStream APIs like write(io, bytes) and read(io, n), and it worked but only for the first value. Every v…

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## [Reverse rule in Enzyme for an implicit function](https://discourse.julialang.org/t/reverse-rule-in-enzyme-for-an-implicit-function/131327)

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**Author:** [@Tamas\_Papp](https://discourse.julialang.org/u/Tamas_Papp)\
**Replies:** 2\
**Last updated:** [August 4, 2025, 1:19pm UTC](https://discourse.julialang.org/t/reverse-rule-in-enzyme-for-an-implicit-function/131327 "2025-08-04T13:19:08Z")

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Suppose H is the cdf of a distribution, A, B are real numbers, and p is defined by p = H(p A + (1 - p) B) This can be implemented simply in Julia as using Roots, Distributions struct Problem{T,S} H::T A::S …

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## [Dyad vs Dyad](https://discourse.julialang.org/t/dyad-vs-dyad/131330)

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**Author:** [@zdenek\_hurak](https://discourse.julialang.org/u/zdenek_hurak)\
**Replies:** 0\
**Last updated:** [August 4, 2025, 12:15pm UTC](https://discourse.julialang.org/t/dyad-vs-dyad/131330 "2025-08-04T12:15:56Z")

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I have just noticed that besides Dyad, there is also Dyad (https://www.dyad.sh). By the way, both referring to AI. I bet that it will happen frequently that people searching for one will be directed to the other. But per…

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## [Spherical to cartesian coordinate transformation](https://discourse.julialang.org/t/spherical-to-cartesian-coordinate-transformation/131202)

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**Author:** [@raman\_kumar](https://discourse.julialang.org/u/raman_kumar)\
**Replies:** 1\
**Last updated:** [August 4, 2025, 11:23am UTC](https://discourse.julialang.org/t/spherical-to-cartesian-coordinate-transformation/131202 "2025-08-04T11:23:48Z")

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How to convert spherical coordinates points to Cartesian coordinates points? using Meshes, CoordRefSystems ,GLMakie, LinearAlgebra, Unitful r = Float32\[1.6, 1.754088, 1.9230156, 2.1082115, 2.311243, 2.5338273, 2.77784…

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## [Mind maps in Julia](https://discourse.julialang.org/t/mind-maps-in-julia/131321)

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**Author:** [@rafael.guerra](https://discourse.julialang.org/u/rafael.guerra)\
**Replies:** 4\
**Last updated:** [August 4, 2025, 7:44am UTC](https://discourse.julialang.org/t/mind-maps-in-julia/131321 "2025-08-04T07:44:27Z")

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Is there any work on creating mind maps using Julia? I’ve started using the free version of MindMup, which lets us save and open mind maps on Google Drive. It is user-friendly and also lets users open Freemind maps. Ho…

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## [Finalizer triggers "task switch not allowed" when used under multi-threaded GC](https://discourse.julialang.org/t/finalizer-triggers-task-switch-not-allowed-when-used-under-multi-threaded-gc/131232)

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**Author:** [@Cyunkitlau](https://discourse.julialang.org/u/Cyunkitlau)\
**Replies:** 7\
**Last updated:** [August 4, 2025, 4:39am UTC](https://discourse.julialang.org/t/finalizer-triggers-task-switch-not-allowed-when-used-under-multi-threaded-gc/131232 "2025-08-04T04:39:03Z")

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Hi there: I’m working on parameter identification using ModelingToolkit-based ODE models. I construct a symbolic system using ModelingToolkit.jl and build a custom loss function, which is optimized under multithreaded…

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## [Coloring part of the background with a specific color](https://discourse.julialang.org/t/coloring-part-of-the-background-with-a-specific-color/131312)

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**Author:** [@imantha](https://discourse.julialang.org/u/imantha)\
**Replies:** 1\
**Last updated:** [August 3, 2025, 5:43am UTC](https://discourse.julialang.org/t/coloring-part-of-the-background-with-a-specific-color/131312 "2025-08-03T05:43:37Z")

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I am trying to color part of the background in in a plot with a specific color and unsure how to achieve it. In this case I want to color x \< 9 in grey and x\> 9 in orange. Any idea how to do it. This is just adds the …

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## [Convergence Issues with Controllable Switch and Square Wave using MTK](https://discourse.julialang.org/t/convergence-issues-with-controllable-switch-and-square-wave-using-mtk/131264)

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**Author:** [@junmorenodi99](https://discourse.julialang.org/u/junmorenodi99)\
**Replies:** 3\
**Last updated:** [August 3, 2025, 1:13am UTC](https://discourse.julialang.org/t/convergence-issues-with-controllable-switch-and-square-wave-using-mtk/131264 "2025-08-03T01:13:36Z")

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Hi everyone, I am new to the Julia community and I’m interested in the applications of the ModelingToolkit package. In particular, I’m trying to simulate a switching circuit using an External Control Signal and a Cont…

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## [How to tweak PolarAxis?](https://discourse.julialang.org/t/how-to-tweak-polaraxis/131286)

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**Author:** [@vladdez](https://discourse.julialang.org/u/vladdez)\
**Replies:** 2\
**Last updated:** [August 2, 2025, 3:14pm UTC](https://discourse.julialang.org/t/how-to-tweak-polaraxis/131286 "2025-08-02T15:14:30Z")

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Two things I would like to clarify: How to remove these empty areas marked by red How to correctly put labels at their places: at least put ylabel tilted. As you see I used dummy axis, because PolarAxis can not put the…

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## [Callback in DifferentialEquation.jl changes the \`p\` parameter vector. Is this expected behaviour?](https://discourse.julialang.org/t/callback-in-differentialequation-jl-changes-the-p-parameter-vector-is-this-expected-behaviour/131273)

<div class="topic-metadata">

**Author:** [@Vitor\_Patricio\_Canta](https://discourse.julialang.org/u/Vitor_Patricio_Canta)\
**Replies:** 3\
**Last updated:** [August 2, 2025, 9:33am UTC](https://discourse.julialang.org/t/callback-in-differentialequation-jl-changes-the-p-parameter-vector-is-this-expected-behaviour/131273 "2025-08-02T09:33:06Z")

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This is a MWE showing that p defined outside of the integrator is also modified by the callback. Is this expected behaviour? Thanks, using OrdinaryDiffEq function rhs(du, u, p, t) V, Q, c\_in = p c = u\[1\] d…

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