# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=354

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**Page:** 355

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## [Gnuplot.jl : Filled contour plot with constant color between contour lines](https://discourse.julialang.org/t/gnuplot-jl-filled-contour-plot-with-constant-color-between-contour-lines/63876)

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**Author:** [@Inna](https://discourse.julialang.org/u/Inna)\
**Replies:** 3\
**Last updated:** [July 2, 2021, 8:41am UTC](https://discourse.julialang.org/t/gnuplot-jl-filled-contour-plot-with-constant-color-between-contour-lines/63876 "2021-07-02T08:41:45Z")

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Hello, using Gnuplot I want to plot contour lines with constant color between them. my code (from https://lazarusa.github.io/gnuplot-examples/menu1/) : x = y = -15:0.33:15 fz(x,y) = sin.(sqrt.(x.^2 + y.^2))./sqrt.(x.…

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## [Help needed with CUDA](https://discourse.julialang.org/t/help-needed-with-cuda/63923)

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**Author:** [@Fabrice\_Rosay](https://discourse.julialang.org/u/Fabrice_Rosay)\
**Replies:** 2\
**Last updated:** [July 2, 2021, 6:31am UTC](https://discourse.julialang.org/t/help-needed-with-cuda/63923 "2021-07-02T06:31:39Z")

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“Oups I did it again”, but I don’t really know what. Suddenly CUDA won’t compile anymore. I got a warning message: WARNING: both ExprTools and LLVM export “parameters”; uses of it in module CUDA must be qualified and …

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## [Using intermediate results in conditional Gibbs in Turing](https://discourse.julialang.org/t/using-intermediate-results-in-conditional-gibbs-in-turing/58203)

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**Author:** [@jbmuir](https://discourse.julialang.org/u/jbmuir)\
**Replies:** 2\
**Last updated:** [July 2, 2021, 5:12am UTC](https://discourse.julialang.org/t/using-intermediate-results-in-conditional-gibbs-in-turing/58203 "2021-07-02T05:12:08Z")

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I have a problem with an expensive intermediate computation that I have to use both within the normal model definition, and in a conditional Gibbs update - is there some way that I can reuse the computation directly in t…

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## [Constrained parameter in Turing](https://discourse.julialang.org/t/constrained-parameter-in-turing/63869)

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**Author:** [@Farlein](https://discourse.julialang.org/u/Farlein)\
**Replies:** 8\
**Last updated:** [July 1, 2021, 7:38pm UTC](https://discourse.julialang.org/t/constrained-parameter-in-turing/63869 "2021-07-01T19:38:23Z")

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Hi there, I get “ERROR: ArgumentError: Bernoulli: the condition zero(p) \<= p \<= one(p) is not satisfied.” from the code below, when using Turing to fit parameters with a constrain, α\_1 + β\_1 \* t \<=0. From the error, I t…

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## [Event handling in jump problems](https://discourse.julialang.org/t/event-handling-in-jump-problems/63882)

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**Author:** [@skleinbo](https://discourse.julialang.org/u/skleinbo)\
**Replies:** 3\
**Last updated:** [July 1, 2021, 4:40pm UTC](https://discourse.julialang.org/t/event-handling-in-jump-problems/63882 "2021-07-01T16:40:26Z")

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Consider for the sake of a minimal example the following pure jump problem. rn2 = @reaction\_network begin a, 0 --\> X end a prob2\_jump = JumpProblem(rn2, DiscreteProblem(rn2, \[0\], (0.0, 10.0), \[1.0\]), Direct()) I w…

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## [Great Makie examples](https://discourse.julialang.org/t/great-makie-examples/63820)

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**Author:** [@sdanisch](https://discourse.julialang.org/u/sdanisch)\
**Replies:** 1\
**Last updated:** [June 30, 2021, 2:26pm UTC](https://discourse.julialang.org/t/great-makie-examples/63820 "2021-06-30T14:26:44Z")

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I’d love to show off some outstanding Makie examples at JuliaCon - and in general work towards collecting examples to show off Makies capabilities and get an overview of what people are up to. Code would be great for fu…

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## [How to make a user-defined objective function with mulitple vector variable and parameter arguments?](https://discourse.julialang.org/t/how-to-make-a-user-defined-objective-function-with-mulitple-vector-variable-and-parameter-arguments/63849)

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**Author:** [@thompsonmj](https://discourse.julialang.org/u/thompsonmj)\
**Replies:** 6\
**Last updated:** [July 1, 2021, 2:18am UTC](https://discourse.julialang.org/t/how-to-make-a-user-defined-objective-function-with-mulitple-vector-variable-and-parameter-arguments/63849 "2021-07-01T02:18:35Z")

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I would like to optimize a set of 3 variable vectors to minimize the total variance in a dataset. I think my problem is in passing variable and parameter vectors into my user-defined objective. I found this question on …

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## [Using Arrow.DictEncode()](https://discourse.julialang.org/t/using-arrow-dictencode/63788)

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**Author:** [@jbshannon](https://discourse.julialang.org/u/jbshannon)\
**Replies:** 1\
**Last updated:** [June 30, 2021, 10:45pm UTC](https://discourse.julialang.org/t/using-arrow-dictencode/63788 "2021-06-30T22:45:47Z")

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How exactly does the Arrow.DictEncode() method work? I’ve tried using it to signal that a DataFrame column be dictionary encoding when writing to a .arrow file, but I can’t see any indication that this works. I’ve looked…

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## [\[Convex.jl\] Objective function of matrix factorization with missing data](https://discourse.julialang.org/t/convex-jl-objective-function-of-matrix-factorization-with-missing-data/34253)

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**Author:** [@4aHxKzD](https://discourse.julialang.org/u/4aHxKzD)\
**Replies:** 21\
**Last updated:** [June 30, 2021, 3:05pm UTC](https://discourse.julialang.org/t/convex-jl-objective-function-of-matrix-factorization-with-missing-data/34253 "2021-06-30T15:05:27Z")

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I’m trying to solve a matrix factorization problem with alternating minimization. My data matrix has missing entries and because of that I can not simply write my objective function as: # A is a n x m data matrix n, m…

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## [Julia + Notebook memory leak](https://discourse.julialang.org/t/julia-notebook-memory-leak/63830)

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**Author:** [@Xeos](https://discourse.julialang.org/u/Xeos)\
**Replies:** 2\
**Last updated:** [June 30, 2021, 2:41pm UTC](https://discourse.julialang.org/t/julia-notebook-memory-leak/63830 "2021-06-30T14:41:20Z")

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Hi, I’ve started trying out jupyterlab with IJulia to see if I could free myself from some large data loading processes that take a lot of time at every run. The CSV I’m working on is decently large (2GB) which then ta…

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## [Why do bigfloats allocate that much ? Could a native rewrite solve the problem?](https://discourse.julialang.org/t/why-do-bigfloats-allocate-that-much-could-a-native-rewrite-solve-the-problem/63809)

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**Author:** [@lrnv](https://discourse.julialang.org/u/lrnv)\
**Replies:** 4\
**Last updated:** [June 30, 2021, 1:40pm UTC](https://discourse.julialang.org/t/why-do-bigfloats-allocate-that-much-could-a-native-rewrite-solve-the-problem/63809 "2021-06-30T13:40:29Z")

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Hi. Everything is in the title: I dont think I understood why BigFloats allocate that much, and why nothing could be done about it. Is there some source, article or doc that explains this ? As @JeffreySarnoff showed in…

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## [ModelingToolkit: troubles using ode\_order\_lowering (A differentiated state's operation must be a \`Sym\`)](https://discourse.julialang.org/t/modelingtoolkit-troubles-using-ode-order-lowering-a-differentiated-states-operation-must-be-a-sym/63716)

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**Author:** [@zdenek\_hurak](https://discourse.julialang.org/u/zdenek_hurak)\
**Replies:** 1\
**Last updated:** [June 30, 2021, 11:56am UTC](https://discourse.julialang.org/t/modelingtoolkit-troubles-using-ode-order-lowering-a-differentiated-states-operation-must-be-a-sym/63716 "2021-06-30T11:56:25Z")

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I am trying to model a simple mechanical chain composed of a few masses interconnected with springs and exposed to friction. Such model comes in the form of a few coupled second-order differential equations. These I mode…

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## [Update parameters in ModelingToolkit using callbacks](https://discourse.julialang.org/t/update-parameters-in-modelingtoolkit-using-callbacks/63770)

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**Author:** [@jairorua](https://discourse.julialang.org/u/jairorua)\
**Replies:** 12\
**Last updated:** [June 30, 2021, 8:19am UTC](https://discourse.julialang.org/t/update-parameters-in-modelingtoolkit-using-callbacks/63770 "2021-06-30T08:19:30Z")

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Hello, I was trying to create a simple control loop with modelingtoolkit. The idea was to have a generic controller whose setpoint can be changed using callbacks during a dynamic simulation. For example: using Modelin…

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## [reactionMechanismSimulator.jl idealGas() call fails due to no default for stoichmatrix](https://discourse.julialang.org/t/reactionmechanismsimulator-jl-idealgas-call-fails-due-to-no-default-for-stoichmatrix/61502)

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**Author:** [@ziolai](https://discourse.julialang.org/u/ziolai)\
**Replies:** 7\
**Last updated:** [June 30, 2021, 6:51am UTC](https://discourse.julialang.org/t/reactionmechanismsimulator-jl-idealgas-call-fails-due-to-no-default-for-stoichmatrix/61502 "2021-06-30T06:51:04Z")

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The basic example of idealGas in reactionMechanism.jl fails to due no default for stoichmatrix. Advice to fix is much appreciated. Thx! using ReactionMechanismSimulator phaseDict = readinput("src/superminimal.rms"…

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## [Delaunay triangulation in best fit plane](https://discourse.julialang.org/t/delaunay-triangulation-in-best-fit-plane/63792)

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**Author:** [@sparrowhawk](https://discourse.julialang.org/u/sparrowhawk)\
**Replies:** 0\
**Last updated:** [June 30, 2021, 2:42am UTC](https://discourse.julialang.org/t/delaunay-triangulation-in-best-fit-plane/63792 "2021-06-30T02:42:07Z")

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Hi I have a set of points scattered in 3D x,y, z, with an associated scalar property f. But these points are very nearly planar, and I want the triangulation of f in a “best fit” plane, which I can then import as a VTK f…

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## [Sub plus (₊) instead of dot in the dot notation in equations displayed by ModelingToolkit](https://discourse.julialang.org/t/sub-plus-instead-of-dot-in-the-dot-notation-in-equations-displayed-by-modelingtoolkit/61113)

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**Author:** [@zdenek\_hurak](https://discourse.julialang.org/u/zdenek_hurak)\
**Replies:** 4\
**Last updated:** [June 29, 2021, 6:45pm UTC](https://discourse.julialang.org/t/sub-plus-instead-of-dot-in-the-dot-notation-in-equations-displayed-by-modelingtoolkit/61113 "2021-06-29T18:45:49Z")

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I was just wondering what was the reason for displaying the MTK equations using (for example) capacitor₊n₊v instead of capacitor.n.v (as in the RC Circuit example). Couldn’t dots be used for displaying as well (when they…

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## [Convex.jl matrix constraints interface : How can i supply this matrix?](https://discourse.julialang.org/t/convex-jl-matrix-constraints-interface-how-can-i-supply-this-matrix/63753)

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**Author:** [@lrnv](https://discourse.julialang.org/u/lrnv)\
**Replies:** 2\
**Last updated:** [June 29, 2021, 5:32pm UTC](https://discourse.julialang.org/t/convex-jl-matrix-constraints-interface-how-can-i-supply-this-matrix/63753 "2021-06-29T17:32:36Z")

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Hi, I want to constraint some matrix that is given as a linear functions of the variables to be semi-definite positive. However, I found something strange : function get\_hankels(s,a,b) m = length(s)-1 if iseven…

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## [GLMakie Method error (Makie.image!)](https://discourse.julialang.org/t/glmakie-method-error-makie-image/63090)

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**Author:** [@Jake](https://discourse.julialang.org/u/Jake)\
**Replies:** 9\
**Last updated:** [June 29, 2021, 1:22pm UTC](https://discourse.julialang.org/t/glmakie-method-error-makie-image/63090 "2021-06-29T13:22:14Z")

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I am trying to duplicate the example on the VideoIO github page that uses Makie. My code is very similar to this example but using some cell phone video from a Blackberry Key2. using VideoIO using GLMakie path = strin…

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## [Display image in Dash app](https://discourse.julialang.org/t/display-image-in-dash-app/63745)

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**Author:** [@Aju](https://discourse.julialang.org/u/Aju)\
**Replies:** 0\
**Last updated:** [June 29, 2021, 12:05pm UTC](https://discourse.julialang.org/t/display-image-in-dash-app/63745 "2021-06-29T12:05:02Z")

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Hello, I am currently building an app for image visualisation using Dash platform. But, I am unable to find the right graph to display the image, which could be a 2D array or 3D array with RGB channels. Here is a simple…

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## [Hypergeometric functions](https://discourse.julialang.org/t/hypergeometric-functions/63621)

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**Author:** [@marcobonici](https://discourse.julialang.org/u/marcobonici)\
**Replies:** 6\
**Last updated:** [June 29, 2021, 9:48am UTC](https://discourse.julialang.org/t/hypergeometric-functions/63621 "2021-06-29T09:48:29Z")

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Hello, I need to evaluate the Gauss Hypergeometric functions \_2F\_1(a,b;c;z). Here are some specifications for the arguments of this function a has compex values. The real part is \\sim2 (and is strictly positive), whi…

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## [What happens if I set more threads than available?](https://discourse.julialang.org/t/what-happens-if-i-set-more-threads-than-available/63717)

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**Author:** [@fredih](https://discourse.julialang.org/u/fredih)\
**Replies:** 2\
**Last updated:** [June 29, 2021, 3:06am UTC](https://discourse.julialang.org/t/what-happens-if-i-set-more-threads-than-available/63717 "2021-06-29T03:06:16Z")

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My computer has 8 cores, so use set\_optimizer\_attribute(myModel, "threads", 8) before starting the optimization. What would happen if I use the exact same code on another computer that has, for example, 4 cores? The prog…

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## [Eigenvectors from quadratic form of a low-rank matrix](https://discourse.julialang.org/t/eigenvectors-from-quadratic-form-of-a-low-rank-matrix/63715)

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**Author:** [@mleprovost](https://discourse.julialang.org/u/mleprovost)\
**Replies:** 2\
**Last updated:** [June 28, 2021, 10:07pm UTC](https://discourse.julialang.org/t/eigenvectors-from-quadratic-form-of-a-low-rank-matrix/63715 "2021-06-28T22:07:14Z")

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Hello, I would like to compute the leading eigenvectors of a positive semi-definite matrix A with a low-rank structure. Are you aware of method that only rely on evaluations of y^\\top A x for arbitrary y, x vectors?

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## [Center colorbar ticks in a categorical colorbar in Makie.jl](https://discourse.julialang.org/t/center-colorbar-ticks-in-a-categorical-colorbar-in-makie-jl/63691)

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**Author:** [@Datseris](https://discourse.julialang.org/u/Datseris)\
**Replies:** 4\
**Last updated:** [June 28, 2021, 1:52pm UTC](https://discourse.julialang.org/t/center-colorbar-ticks-in-a-categorical-colorbar-in-makie-jl/63691 "2021-06-28T13:52:45Z")

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MWE: using GLMakie xg = range(0, 10; length = 100) yg = range(0, 10; length = 100) bsn = rand(1:5, (100, 100)) fig = Figure(resolution = (700,600)) display(fig) colors = \[:black, :blue, :red, :teal, :yellow\] cmap = …

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## [3D scatter with AlgebraOfGraphics.jl](https://discourse.julialang.org/t/3d-scatter-with-algebraofgraphics-jl/63686)

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**Author:** [@juliohm](https://discourse.julialang.org/u/juliohm)\
**Replies:** 7\
**Last updated:** [June 28, 2021, 1:18pm UTC](https://discourse.julialang.org/t/3d-scatter-with-algebraofgraphics-jl/63686 "2021-06-28T13:18:50Z")

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Is it possible to get a 3D scatter plot with AlgebraOfGraphics.jl? I tried it with data(df) \* mapping(:X, :Y, :Z) |\> draw but it only shows a 2D scatter as if the3rd argument :Z was ignored.

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## [Help with constraints to select and/or insert columns to a matrix](https://discourse.julialang.org/t/help-with-constraints-to-select-and-or-insert-columns-to-a-matrix/63654)

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**Author:** [@DrChainsaw](https://discourse.julialang.org/u/DrChainsaw)\
**Replies:** 3\
**Last updated:** [June 28, 2021, 10:48am UTC](https://discourse.julialang.org/t/help-with-constraints-to-select-and-or-insert-columns-to-a-matrix/63654 "2021-06-28T10:48:12Z")

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I suppose this might be more of a generic MIP formulation question, but I’m not sure stackexchange would accept it and in here I can at least provide some almost working code using JuMP. Simple context free question is …

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## [Drawing a median line in a histogram in Makie](https://discourse.julialang.org/t/drawing-a-median-line-in-a-histogram-in-makie/63359)

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**Author:** [@ericphanson](https://discourse.julialang.org/u/ericphanson)\
**Replies:** 5\
**Last updated:** [June 28, 2021, 10:14am UTC](https://discourse.julialang.org/t/drawing-a-median-line-in-a-histogram-in-makie/63359 "2021-06-28T10:14:33Z")

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I can’t figure out a non-manual way to do this: mwe\_fig = let fig = Figure() data = randn(1000) .+ 1 ax = Axis(fig\[1,1\]; xlabel="Value", ylabel="Count") hist!(ax, data) m = median(data) m\_color = Makie.wong\_colors…

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## [Weights update in Flux](https://discourse.julialang.org/t/weights-update-in-flux/63657)

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**Author:** [@Mariana](https://discourse.julialang.org/u/Mariana)\
**Replies:** 2\
**Last updated:** [June 28, 2021, 9:24am UTC](https://discourse.julialang.org/t/weights-update-in-flux/63657 "2021-06-28T09:24:16Z")

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Hello! I am trying to use Flux to train a neural network but, in this case I don’t have the target values for the output. I will try to formulate a simpler version of my problem. Suppose I have an input input = \[0.8 0…

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## [Get a legend with twinx()](https://discourse.julialang.org/t/get-a-legend-with-twinx/63672)

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**Author:** [@Paolo\_Jara](https://discourse.julialang.org/u/Paolo_Jara)\
**Replies:** 1\
**Last updated:** [June 28, 2021, 8:39am UTC](https://discourse.julialang.org/t/get-a-legend-with-twinx/63672 "2021-06-28T08:39:50Z")

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Hi, I’m using the twinx () command, is there a way to have both labels in the same legend? using Plots x12=randn(10) y12=1000\*randn(10) plot(x12, label="x12") plot!(twinx(), y12, c=:red, legend=:bottomleft, label="y12")…

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## [Round CategoricalArrays.cut labels](https://discourse.julialang.org/t/round-categoricalarrays-cut-labels/63674)

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**Author:** [@jzr](https://discourse.julialang.org/u/jzr)\
**Replies:** 1\
**Last updated:** [June 28, 2021, 7:09am UTC](https://discourse.julialang.org/t/round-categoricalarrays-cut-labels/63674 "2021-06-28T07:09:47Z")

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How can I round the labels to two digits without changing anything else? using CategoricalArrays cut(rand(5), 2, labels=((from, to, i;kw...)-\>"$(round(from, digits=2))-$(round(to, digits=2))")) ERROR: MethodError: no m…

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## [First CUDA Program- Addressing Scalar Indexing](https://discourse.julialang.org/t/first-cuda-program-addressing-scalar-indexing/63396)

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**Author:** [@loki](https://discourse.julialang.org/u/loki)\
**Replies:** 5\
**Last updated:** [June 28, 2021, 5:50am UTC](https://discourse.julialang.org/t/first-cuda-program-addressing-scalar-indexing/63396 "2021-06-28T05:50:41Z")

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Hello, I am trying to get my feet wet in the world of CUDA programming. I started with some CPU code that I previously written but have been having some trouble with Scalar Indexing slowing down the computation. The prob…

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