# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=328

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**Page:** 329

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## ["rv\_to\_tle" function in satellite toolbox](https://discourse.julialang.org/t/rv-to-tle-function-in-satellite-toolbox/69919)

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**Author:** [@sxd190026](https://discourse.julialang.org/u/sxd190026)\
**Replies:** 2\
**Last updated:** [October 18, 2021, 3:19am UTC](https://discourse.julialang.org/t/rv-to-tle-function-in-satellite-toolbox/69919 "2021-10-18T03:19:17Z")

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I am using SGP4 package in satellite toolbox. But I want to modify bstar term at every orbit. For this purpose, I am trying to propagate a given tle for a single orbit and define a new tle at that point. Then I want to p…

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## [Using JuMP to solve the heat equation - performance tips requested](https://discourse.julialang.org/t/using-jump-to-solve-the-heat-equation-performance-tips-requested/69749)

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**Author:** [@krusharth.shah](https://discourse.julialang.org/u/krusharth.shah)\
**Replies:** 11\
**Last updated:** [October 17, 2021, 7:55pm UTC](https://discourse.julialang.org/t/using-jump-to-solve-the-heat-equation-performance-tips-requested/69749 "2021-10-17T19:55:32Z")

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Hello everyone! I am studying MSc Mechatronics and currently working on my scientific project. It is regarding making the Julia code of 1D Heat equation faster. With this message, I have also attached the Julia source…

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## [My gradients IdDIct keys are GlobalRefs instead of arrays](https://discourse.julialang.org/t/my-gradients-iddict-keys-are-globalrefs-instead-of-arrays/69665)

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**Author:** [@Johan-Gronqvist](https://discourse.julialang.org/u/Johan-Gronqvist)\
**Replies:** 2\
**Last updated:** [October 17, 2021, 5:50pm UTC](https://discourse.julialang.org/t/my-gradients-iddict-keys-are-globalrefs-instead-of-arrays/69665 "2021-10-17T17:50:11Z")

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My gradients sometimes appear with keys of type GlobalRef. I do not understand why and I do not understand how to change that. Example code: using Flux function h(x; bs=bs) for b in bs\[1:end-1\] x = x+b …

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## [Error using Differential Equations and Unitful](https://discourse.julialang.org/t/error-using-differential-equations-and-unitful/69909)

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**Author:** [@MisterBiggs](https://discourse.julialang.org/u/MisterBiggs)\
**Replies:** 5\
**Last updated:** [October 17, 2021, 4:59pm UTC](https://discourse.julialang.org/t/error-using-differential-equations-and-unitful/69909 "2021-10-17T16:59:54Z")

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I am using Differential Equations and Unitful together for the first time and I am running into the following error when trying to solve my OdeProblem: ArgumentError: zero(Unitful.Quantity{Float64}) not defined. My ODE …

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## [Gnuplot (Gaston.jl) backend for Plots](https://discourse.julialang.org/t/gnuplot-gaston-jl-backend-for-plots/64122)

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**Author:** [@isentropic](https://discourse.julialang.org/u/isentropic)\
**Replies:** 4\
**Last updated:** [October 17, 2021, 4:10pm UTC](https://discourse.julialang.org/t/gnuplot-gaston-jl-backend-for-plots/64122 "2021-10-17T16:10:53Z")

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Dear Plot users, Experimental gnuplot/gaston.jl backend has been merged into Plots.jl master branch (including a release). My primary goal is to have a lightweight backend in plots that supports REPL plotting. Since man…

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## [Data augmentation question (CIFAR10)](https://discourse.julialang.org/t/data-augmentation-question-cifar10/69667)

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**Author:** [@Rasmus\_Hoier](https://discourse.julialang.org/u/Rasmus_Hoier)\
**Replies:** 9\
**Last updated:** [October 17, 2021, 9:36am UTC](https://discourse.julialang.org/t/data-augmentation-question-cifar10/69667 "2021-10-17T09:36:22Z")

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Hi, I am training a CNN on CIFAR10 (via Flux.DataLoader) and am trying to apply some stochastic data transformations to each batch of data at runtime. My goal is to apply the following operations to each batch I get fr…

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## [Function parameter estimation similar to Octave fminsearch](https://discourse.julialang.org/t/function-parameter-estimation-similar-to-octave-fminsearch/69485)

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**Author:** [@John\_Peach](https://discourse.julialang.org/u/John_Peach)\
**Replies:** 4\
**Last updated:** [October 16, 2021, 6:33pm UTC](https://discourse.julialang.org/t/function-parameter-estimation-similar-to-octave-fminsearch/69485 "2021-10-16T18:33:43Z")

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I’m trying to solve a simple parameter estimation problem in Julia similar to how fminsearch works in Octave/Matlab. The RAFF.jl package seemed like a nice approach, but perhaps there’s a better way? For context, I have…

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## [\[ANN\] DataFramesMeta 0.10.0 release](https://discourse.julialang.org/t/ann-dataframesmeta-0-10-0-release/69903)

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**Author:** [@pdeffebach](https://discourse.julialang.org/u/pdeffebach)\
**Replies:** 0\
**Last updated:** [October 16, 2021, 4:38pm UTC](https://discourse.julialang.org/t/ann-dataframesmeta-0-10-0-release/69903 "2021-10-16T16:38:53Z")

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We are pleased to announce the release of DataFramesMeta.jl version 0.10.0. This release adds the @astable macro-flag, which is similar to the @t macro-flag in DataFrameMacros.jl. Thanks to @jules for taking initiating …

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## [\*Cache and \*ConstantCache versions of ODE solvers. What is the difference?](https://discourse.julialang.org/t/cache-and-constantcache-versions-of-ode-solvers-what-is-the-difference/69810)

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**Author:** [@Andrey](https://discourse.julialang.org/u/Andrey)\
**Replies:** 1\
**Last updated:** [October 16, 2021, 1:30pm UTC](https://discourse.julialang.org/t/cache-and-constantcache-versions-of-ode-solvers-what-is-the-difference/69810 "2021-10-16T13:30:34Z")

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I was going through Rodas4 solver source code and found that there are 2 different implementations of this solver - Rodas4Cache and Rodas4ConstantCache. Is there any principal difference between these 2 variants? It lo…

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## [PES2021 Players Comparison](https://discourse.julialang.org/t/pes2021-players-comparison/69894)

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**Author:** [@cepel](https://discourse.julialang.org/u/cepel)\
**Replies:** 0\
**Last updated:** [October 16, 2021, 12:19pm UTC](https://discourse.julialang.org/t/pes2021-players-comparison/69894 "2021-10-16T12:19:46Z")

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Hey everyone! I developed a dash julia application that allows you to compare PES2021 players on a radar chart. You can select multiple players and update the graph. Feel free to review the code on GitHub and ask me any…

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## [JuMP with absolute value constraint on variables](https://discourse.julialang.org/t/jump-with-absolute-value-constraint-on-variables/69863)

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**Author:** [@qiujj](https://discourse.julialang.org/u/qiujj)\
**Replies:** 2\
**Last updated:** [October 16, 2021, 12:03pm UTC](https://discourse.julialang.org/t/jump-with-absolute-value-constraint-on-variables/69863 "2021-10-16T12:03:48Z")

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I’m trying to optimize a function with absolute constraints on its variable (a\<=|x|\<=b), but I don’t know how to replace function “abs” in JuMP constraint or variable. At first I wrote this one, where x\_min and x\_max ar…

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## [Not a question, but a 3D PlotlyJS gallery](https://discourse.julialang.org/t/not-a-question-but-a-3d-plotlyjs-gallery/65063)

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**Author:** [@empet](https://discourse.julialang.org/u/empet)\
**Replies:** 7\
**Last updated:** [October 16, 2021, 11:20am UTC](https://discourse.julialang.org/t/not-a-question-but-a-3d-plotlyjs-gallery/65063 "2021-10-16T11:20:00Z")

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I’m a Julia beginner, as you may have noticed from the basic questions I have asked here. To practice it I created a small project and gallery of 3D PlotlyJS charts, here: https://github.com/empet/3D-Viz-with-PlotlyJ…

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## [Optimizing model description](https://discourse.julialang.org/t/optimizing-model-description/69885)

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**Author:** [@BLI](https://discourse.julialang.org/u/BLI)\
**Replies:** 0\
**Last updated:** [October 16, 2021, 11:05am UTC](https://discourse.julialang.org/t/optimizing-model-description/69885 "2021-10-16T11:05:52Z")

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I need to optimize a model description for an ODEProblem, which is a hand-coded discretization of a PDE (so the state is a matrix). I know I should… avoid creating arrays in the model. My plan is to instead operate on …

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## [Using PPOPolicy with custom environment with action masking in ReinforcementLearning.jl](https://discourse.julialang.org/t/using-ppopolicy-with-custom-environment-with-action-masking-in-reinforcementlearning-jl/69625)

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**Author:** [@mfg](https://discourse.julialang.org/u/mfg)\
**Replies:** 14\
**Last updated:** [October 16, 2021, 3:30am UTC](https://discourse.julialang.org/t/using-ppopolicy-with-custom-environment-with-action-masking-in-reinforcementlearning-jl/69625 "2021-10-16T03:30:47Z")

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In order to use Action Masking with he PPOPolicy i think i have to use a MaskedPPOTrajectory. The legal\_actions\_mask gets updated in the update! function with the result of legal\_action\_space\_mask(env), but afaiu this sh…

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## [Interval Compiler for Sound Float Computations](https://discourse.julialang.org/t/interval-compiler-for-sound-float-computations/69857)

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**Author:** [@JeffreySarnoff](https://discourse.julialang.org/u/JeffreySarnoff)\
**Replies:** 0\
**Last updated:** [October 15, 2021, 9:38pm UTC](https://discourse.julialang.org/t/interval-compiler-for-sound-float-computations/69857 "2021-10-15T21:38:55Z")

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For those interested in llvm mods for enhancing floats. IGen is a source-to-source compiler for interval arithmetic. IGen takes as input a C function doing floating-point computations, possibly using SIMD intrinsics, a…

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## [Independent variable t - @parameter or @variable?](https://discourse.julialang.org/t/independent-variable-t-parameter-or-variable/69619)

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**Author:** [@SCher](https://discourse.julialang.org/u/SCher)\
**Replies:** 1\
**Last updated:** [October 15, 2021, 2:37pm UTC](https://discourse.julialang.org/t/independent-variable-t-parameter-or-variable/69619 "2021-10-15T14:37:29Z")

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While creating models in MTK for a system of ODEs, should time t be specified as a @parameter or @variable? I have seen different examples use both ways, and both seem to work. Which is recommended? Any particular reaso…

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## [Solving time-dependent system of equations from Modelica with ModelingToolkit - hasmetadata error](https://discourse.julialang.org/t/solving-time-dependent-system-of-equations-from-modelica-with-modelingtoolkit-hasmetadata-error/69817)

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**Author:** [@Pere](https://discourse.julialang.org/u/Pere)\
**Replies:** 4\
**Last updated:** [October 15, 2021, 1:37pm UTC](https://discourse.julialang.org/t/solving-time-dependent-system-of-equations-from-modelica-with-modelingtoolkit-hasmetadata-error/69817 "2021-10-15T13:37:29Z")

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I’m trying to find \\bar{v}\_{dq}^+ and \\bar{v}\_{dq}^- in the equation below where {v}\_{dq}^+ and {v}\_{dq}^- are known time-varying signals. I’ve done this in Modelica, but I’d like to try with Julia. This is the Mod…

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## [Sparsity in DifferentialEquations: how to exploit?](https://discourse.julialang.org/t/sparsity-in-differentialequations-how-to-exploit/69808)

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**Author:** [@ignace](https://discourse.julialang.org/u/ignace)\
**Replies:** 8\
**Last updated:** [October 15, 2021, 1:35pm UTC](https://discourse.julialang.org/t/sparsity-in-differentialequations-how-to-exploit/69808 "2021-10-15T13:35:20Z")

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Sorry for bothering you with a small request for help. I have the following code, but I would expect the solution to the one-timestep ODEProblem (using implicit Euler) to be computed in a time similar to AA\\b or (I+AA)…

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## [Makie mouse click position](https://discourse.julialang.org/t/makie-mouse-click-position/9062)

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**Author:** [@yakir12](https://discourse.julialang.org/u/yakir12)\
**Replies:** 8\
**Last updated:** [October 15, 2021, 8:12am UTC](https://discourse.julialang.org/t/makie-mouse-click-position/9062 "2021-10-15T08:12:24Z")

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Can someone please show me how to get the location of a mouse left click on a Makie.jl scene ? Here’s what I have now: using Makie img = rand(100,100) scene = Scene(resolution = (100, 100)) heatmap(img) Makie.add\_mouse…

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## [FFTs in probabilistic models](https://discourse.julialang.org/t/ffts-in-probabilistic-models/69775)

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**Author:** [@bdecost](https://discourse.julialang.org/u/bdecost)\
**Replies:** 5\
**Last updated:** [October 15, 2021, 3:19am UTC](https://discourse.julialang.org/t/ffts-in-probabilistic-models/69775 "2021-10-15T03:19:55Z")

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I’m working on a model that involves a Fourier transform, and I’m running the limits of my julia debugging ability I’m using this AbstractFFTs PR to try to get it working with the ForwardDiff backend. (Zygote fails with…

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## [Makie: zoom by keyboard.up/down?](https://discourse.julialang.org/t/makie-zoom-by-keyboard-up-down/69781)

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**Author:** [@Bardo](https://discourse.julialang.org/u/Bardo)\
**Replies:** 0\
**Last updated:** [October 14, 2021, 9:45pm UTC](https://discourse.julialang.org/t/makie-zoom-by-keyboard-up-down/69781 "2021-10-14T21:45:38Z")

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Hi, how to zoom into a plot using keyboard.up/down additionally to the usual mouse scroll? Interesting for laptop use without a mouse. Thx

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## [Julia stats, data, ML: expanding usability](https://discourse.julialang.org/t/julia-stats-data-ml-expanding-usability/67948)

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**Author:** [@mit.edelman](https://discourse.julialang.org/u/mit.edelman)\
**Replies:** 84\
**Last updated:** [October 14, 2021, 3:03pm UTC](https://discourse.julialang.org/t/julia-stats-data-ml-expanding-usability/67948 "2021-10-14T15:03:55Z")

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I’d like to share a presentation that was shared with me by a colleague interested in making Julia’s ecosystem more widely used. His conjecture is that Julia has remarkable capabilities, but if we only increased the usab…

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## [Makie: fitting of x- or y-axes to visible data range?](https://discourse.julialang.org/t/makie-fitting-of-x-or-y-axes-to-visible-data-range/69758)

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**Author:** [@Bardo](https://discourse.julialang.org/u/Bardo)\
**Replies:** 0\
**Last updated:** [October 14, 2021, 2:25pm UTC](https://discourse.julialang.org/t/makie-fitting-of-x-or-y-axes-to-visible-data-range/69758 "2021-10-14T14:25:13Z")

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How to optimally fit an x- or y-axis to visible data? (the automatic equivalent of manually x- or y-axis zooming) Related: How to get the minimum/maximum coordinates of visible zoomed in data?

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## [Broadcasting a function on GPU](https://discourse.julialang.org/t/broadcasting-a-function-on-gpu/69694)

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**Author:** [@lodygaw](https://discourse.julialang.org/u/lodygaw)\
**Replies:** 3\
**Last updated:** [October 14, 2021, 1:51pm UTC](https://discourse.julialang.org/t/broadcasting-a-function-on-gpu/69694 "2021-10-14T13:51:36Z")

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Hi, I am looking for some advice on finding the most efficient way to parallelize my code on GPU. Let’s assume the simplified situation: struct MyOtherStruct1 end struct MyOtherStruct2 end struct MyStructType1 end str…

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## [Body Mass Index (BMI) Calculator with Dash Julia](https://discourse.julialang.org/t/body-mass-index-bmi-calculator-with-dash-julia/69711)

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**Author:** [@cepel](https://discourse.julialang.org/u/cepel)\
**Replies:** 0\
**Last updated:** [October 13, 2021, 6:37pm UTC](https://discourse.julialang.org/t/body-mass-index-bmi-calculator-with-dash-julia/69711 "2021-10-13T18:37:11Z")

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Hey everyone! I developed a new Dash Julia application for body mass index (BMI) calculation. You can calculate BMI value and see the weight ranges. Feel free to review the codes on GitHub and ask me anything. Live on …

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## [Multilayer perceptron with multidimensional output array using Flux](https://discourse.julialang.org/t/multilayer-perceptron-with-multidimensional-output-array-using-flux/69747)

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**Author:** [@FrootLoops](https://discourse.julialang.org/u/FrootLoops)\
**Replies:** 2\
**Last updated:** [October 14, 2021, 12:50pm UTC](https://discourse.julialang.org/t/multilayer-perceptron-with-multidimensional-output-array-using-flux/69747 "2021-10-14T12:50:22Z")

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Hi, I have some problems coding a multilayer perceptron using Flux. My data is given in the form D=(x\_i, y\_i)\_{i=1}^n where x\_i is a scalar and y\_i is a 3-dim vector . I want to train a neural network using flux. Due to…

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## [Makie: Animation via Node() works with text(), but not with scatter()](https://discourse.julialang.org/t/makie-animation-via-node-works-with-text-but-not-with-scatter/28100)

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**Author:** [@Arjen\_Suijker](https://discourse.julialang.org/u/Arjen_Suijker)\
**Replies:** 8\
**Last updated:** [October 14, 2021, 12:39pm UTC](https://discourse.julialang.org/t/makie-animation-via-node-works-with-text-but-not-with-scatter/28100 "2021-10-14T12:39:24Z")

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I have been struggling with this for days, I don’t know if this is a bug or if I’m just missing something. I want to animate both text and and scatters based on real-time input. I’m using Node for this (Observables). Th…

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## [Corrections for juliadatascience book](https://discourse.julialang.org/t/corrections-for-juliadatascience-book/69204)

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**Author:** [@empet](https://discourse.julialang.org/u/empet)\
**Replies:** 23\
**Last updated:** [October 14, 2021, 12:25pm UTC](https://discourse.julialang.org/t/corrections-for-juliadatascience-book/69204 "2021-10-14T12:25:30Z")

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It’s incredible what wrong definitions the authors of the juliadatascience give in their online book, accessible at: https://juliadatascience.io/. There are so many scientists on this forum and no one has read what th…

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## [Forcing Neldermead from Optim.jl to abort when "stuck"](https://discourse.julialang.org/t/forcing-neldermead-from-optim-jl-to-abort-when-stuck/69041)

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**Author:** [@Nikos\_Gianniotis](https://discourse.julialang.org/u/Nikos_Gianniotis)\
**Replies:** 8\
**Last updated:** [October 14, 2021, 12:16pm UTC](https://discourse.julialang.org/t/forcing-neldermead-from-optim-jl-to-abort-when-stuck/69041 "2021-10-14T12:16:32Z")

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I am a very frequent user of the Nelder-Mead optimisation routine (of the excellent Optim.jl package) which I find very effective for problems with a handful of free parameters to tune. I have very little knowledge of ho…

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## [Periodic Boundary conditions in ParallelStencil / ImplicitGlobalGrid](https://discourse.julialang.org/t/periodic-boundary-conditions-in-parallelstencil-implicitglobalgrid/69670)

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**Author:** [@gerhardu](https://discourse.julialang.org/u/gerhardu)\
**Replies:** 2\
**Last updated:** [October 14, 2021, 10:53am UTC](https://discourse.julialang.org/t/periodic-boundary-conditions-in-parallelstencil-implicitglobalgrid/69670 "2021-10-14T10:53:25Z")

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Hello, i want to solve a pde with periodic boundary conditions on multiple processors. There is a good way to do it with Petsc, but i would like to move to julia. Is there a way to do this with ParallelStencil / Impli…

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