# General Usage

**URL:** https://discourse.julialang.org/c/usage/6.md?page=277

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**Page:** 278

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## [What is a model in Julia Flux 0.13 and higher?](https://discourse.julialang.org/t/what-is-a-model-in-julia-flux-0-13-and-higher/100653)

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**Author:** [@Yrogirg](https://discourse.julialang.org/u/Yrogirg)\
**Replies:** 2\
**Last updated:** [June 21, 2023, 2:52pm UTC](https://discourse.julialang.org/t/what-is-a-model-in-julia-flux-0-13-and-higher/100653 "2023-06-21T14:52:12Z")

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Cross post from stackoverflow (flux.jl - What is a model in Julia Flux 0.13 and higher? - Stack Overflow) I want to use Julia Flux for machine learning with custom models (not neural networks, so I won’t be using/combin…

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## [How to set global path?](https://discourse.julialang.org/t/how-to-set-global-path/100639)

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**Author:** [@tomtom](https://discourse.julialang.org/u/tomtom)\
**Replies:** 10\
**Last updated:** [June 21, 2023, 2:34pm UTC](https://discourse.julialang.org/t/how-to-set-global-path/100639 "2023-06-21T14:34:24Z")

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in startup.jl: if Sys.isapple() const ROOT\_PATH = "/Users/Tom/Documents/Julia/" else const ROOT\_PATH = "/home/Tom/Documents/Julia/" end import Abc then in Abc.jl: module Abc include(joinpath(ROOT\_PATH, "exte…

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## [Unhandled task error using pmap](https://discourse.julialang.org/t/unhandled-task-error-using-pmap/87927)

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**Author:** [@poopsilon](https://discourse.julialang.org/u/poopsilon)\
**Replies:** 1\
**Last updated:** [June 21, 2023, 1:55pm UTC](https://discourse.julialang.org/t/unhandled-task-error-using-pmap/87927 "2023-06-21T13:55:28Z")

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Hi, I’m using pmap to distribute a computation to many workers on a cluster, pretty straightforward. Here I am using 1 node and 10 processors. Things seem to be going fine for most cases, but sometimes I get an error li…

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## [Is PlotlyJS.add\_hline!() on y2-axis possible?](https://discourse.julialang.org/t/is-plotlyjs-add-hline-on-y2-axis-possible/100553)

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**Author:** [@ellocco](https://discourse.julialang.org/u/ellocco)\
**Replies:** 1\
**Last updated:** [June 19, 2023, 2:37pm UTC](https://discourse.julialang.org/t/is-plotlyjs-add-hline-on-y2-axis-possible/100553 "2023-06-19T14:37:34Z")

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Is it possible under PlotlyJS to add hlines on “y#” (e.g. “y2”)? Here my sample code: using PlotlyJS # --- function plot\_debug\_hline() scatter1 = PlotlyJS.scatter(;y = \[ 1, 2, 3, 4\], name= "Y1") scat…

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## [Simple things surprisingly broken](https://discourse.julialang.org/t/simple-things-surprisingly-broken/100622)

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**Author:** [@lewis](https://discourse.julialang.org/u/lewis)\
**Replies:** 2\
**Last updated:** [June 21, 2023, 11:54am UTC](https://discourse.julialang.org/t/simple-things-surprisingly-broken/100622 "2023-06-21T11:54:29Z")

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Days ago everything was working beautifully and fast with 1.9. Now, I have mysterious breakage that I can’t figure out. I have installed 1.9.1 and I have installed the package LazyTables. The latter should make no dif…

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## [Debugging performance difference between identical arrays](https://discourse.julialang.org/t/debugging-performance-difference-between-identical-arrays/96714)

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**Author:** [@f.ij](https://discourse.julialang.org/u/f.ij)\
**Replies:** 8\
**Last updated:** [June 21, 2023, 11:39am UTC](https://discourse.julialang.org/t/debugging-performance-difference-between-identical-arrays/96714 "2023-06-21T11:39:01Z")

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I’m working with arrays of the following type Vector{Vector{Tuple{Int32,Float32}}} to represent an adjacency matrix. These are stored in some struct mutable struct SomeStruct ... adj::Vector{Vector{Tuple{Int32,Float…

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## [Change to OpenLibm\_jll modifies find\_library in Libdl from Julia v1.7 to v1.9?](https://discourse.julialang.org/t/change-to-openlibm-jll-modifies-find-library-in-libdl-from-julia-v1-7-to-v1-9/100570)

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**Author:** [@diadora77](https://discourse.julialang.org/u/diadora77)\
**Replies:** 2\
**Last updated:** [June 21, 2023, 1:18am UTC](https://discourse.julialang.org/t/change-to-openlibm-jll-modifies-find-library-in-libdl-from-julia-v1-7-to-v1-9/100570 "2023-06-21T01:18:23Z")

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Hi - I recently updated from Julia v1.7 to v1.9. In using find\_library from Libdl.jl package, get different behavior. In v1.7, find\_library will work without specifying extension while in v1.9 it doesn’t. Both can fi…

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## [How to cross-compile using PackageCompiler?](https://discourse.julialang.org/t/how-to-cross-compile-using-packagecompiler/100551)

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**Author:** [@bertulli](https://discourse.julialang.org/u/bertulli)\
**Replies:** 14\
**Last updated:** [June 21, 2023, 1:15am UTC](https://discourse.julialang.org/t/how-to-cross-compile-using-packagecompiler/100551 "2023-06-21T01:15:25Z")

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Hi all! I am trying to use PackageCompiler to build a stand-alone app. Since I need to potentially ship it to different host systems, I need to cross-compile my project. The PackageCompiler’s docs say nothing about it (…

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## [Unable to automatically download/install artifact 'Ghostscript' from sources listed in .../.julia/...Artifects.toml](https://discourse.julialang.org/t/unable-to-automatically-download-install-artifact-ghostscript-from-sources-listed-in-julia-artifects-toml/98901)

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**Author:** [@chunjiw](https://discourse.julialang.org/u/chunjiw)\
**Replies:** 3\
**Last updated:** [June 20, 2023, 10:43pm UTC](https://discourse.julialang.org/t/unable-to-automatically-download-install-artifact-ghostscript-from-sources-listed-in-julia-artifects-toml/98901 "2023-06-20T22:43:33Z")

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I encounter this error using Julia 1.9.0 when adding a local package. The whole error message is Resolving package versions... Downloaded artifact: Ghostscript Downloaded artifact: Ghostscript ERROR: Unable to au…

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## [Solving Differential Equation with Delay](https://discourse.julialang.org/t/solving-differential-equation-with-delay/100601)

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**Author:** [@CurioMath](https://discourse.julialang.org/u/CurioMath)\
**Replies:** 2\
**Last updated:** [June 20, 2023, 1:58pm UTC](https://discourse.julialang.org/t/solving-differential-equation-with-delay/100601 "2023-06-20T13:58:23Z")

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Hi, I have an ODE problem to which I need to apply delay . But trying to solve as per the documentation of delay differential equations doesn’t seem to work for me…Can someone please lend a hand? Here is the ODE Proble…

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## [How to predict the new system from the pre-trained weight in NeuralPDE](https://discourse.julialang.org/t/how-to-predict-the-new-system-from-the-pre-trained-weight-in-neuralpde/100587)

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**Author:** [@Ethan\_Tran](https://discourse.julialang.org/u/Ethan_Tran)\
**Replies:** 2\
**Last updated:** [June 20, 2023, 1:17pm UTC](https://discourse.julialang.org/t/how-to-predict-the-new-system-from-the-pre-trained-weight-in-neuralpde/100587 "2023-06-20T13:17:03Z")

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I used the code below to solve the ODE system and save trained weight. using NeuralPDE, Lux, ModelingToolkit, Optimization, OptimizationOptimJL import ModelingToolkit: Interval, infimum, supremum @parameters t @variabl…

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## [Syntax for constructing a 1x1 matrix](https://discourse.julialang.org/t/syntax-for-constructing-a-1x1-matrix/5207)

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**Author:** [@pablosanjose](https://discourse.julialang.org/u/pablosanjose)\
**Replies:** 12\
**Last updated:** [June 20, 2023, 12:08pm UTC](https://discourse.julialang.org/t/syntax-for-constructing-a-1x1-matrix/5207 "2023-06-20T12:08:07Z")

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Before taking transposes seriously one could conveniently use e.g. \[5\]' to build a 1x1 matrix containing 5. In v0.6+ this results in a RowVector instead. Do we have any compact syntax for building initialized 1x1 matrice…

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## [Check the sum of a certain array index](https://discourse.julialang.org/t/check-the-sum-of-a-certain-array-index/100552)

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**Author:** [@divon](https://discourse.julialang.org/u/divon)\
**Replies:** 19\
**Last updated:** [June 20, 2023, 7:40am UTC](https://discourse.julialang.org/t/check-the-sum-of-a-certain-array-index/100552 "2023-06-20T07:40:34Z")

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Hello everyone, I would like to check the sum of certain indexes in the array. For example, I have the array: a = \[0, 0, 0, 1, 0, 1, 0, 1\] b = \[1, 2, 3, 5\] I will check the sum of a\[1\], a\[2\], a\[3\], and a\[5\]. If the su…

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## [Makie create\_app Font display is not normal](https://discourse.julialang.org/t/makie-create-app-font-display-is-not-normal/100588)

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**Author:** [@13299118606](https://discourse.julialang.org/u/13299118606)\
**Replies:** 1\
**Last updated:** [June 20, 2023, 5:02am UTC](https://discourse.julialang.org/t/makie-create-app-font-display-is-not-normal/100588 "2023-06-20T05:02:44Z")

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Both the original PC and the target PC platform are win10 64-bit Makie (on the original PC) uses PackageCompiler to create an app and migrate it to a PC without a network (on the target PC), it will prompt Download err…

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## [Oy vey: there is an error, but how to find it?](https://discourse.julialang.org/t/oy-vey-there-is-an-error-but-how-to-find-it/100578)

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**Author:** [@PetrKryslUCSD](https://discourse.julialang.org/u/PetrKryslUCSD)\
**Replies:** 3\
**Last updated:** [June 20, 2023, 12:25am UTC](https://discourse.julialang.org/t/oy-vey-there-is-an-error-but-how-to-find-it/100578 "2023-06-20T00:25:50Z")

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## [Required function input types in PyJulia](https://discourse.julialang.org/t/required-function-input-types-in-pyjulia/100580)

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**Author:** [@lkmc](https://discourse.julialang.org/u/lkmc)\
**Replies:** 0\
**Last updated:** [June 19, 2023, 11:18pm UTC](https://discourse.julialang.org/t/required-function-input-types-in-pyjulia/100580 "2023-06-19T23:18:26Z")

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I have a function in Julia that is called from Python and it seems to be enforcing a particular argument type, but I’m not sure how/where because when I change the allowed argument type to what should be the correct thin…

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## [Initializing lots of matrices in the same way](https://discourse.julialang.org/t/initializing-lots-of-matrices-in-the-same-way/100500)

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**Author:** [@hshackle](https://discourse.julialang.org/u/hshackle)\
**Replies:** 19\
**Last updated:** [June 19, 2023, 10:41pm UTC](https://discourse.julialang.org/t/initializing-lots-of-matrices-in-the-same-way/100500 "2023-06-19T22:41:31Z")

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The code I’m working with involves a few dozen matrices, let’s call them a, b, etc. They all end up being used in quite different fashions, so it makes sense to keep them separate rather than packing them all into one la…

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## [Grid data with interpolation](https://discourse.julialang.org/t/grid-data-with-interpolation/100574)

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**Author:** [@lukas\_r](https://discourse.julialang.org/u/lukas_r)\
**Replies:** 2\
**Last updated:** [June 19, 2023, 9:49pm UTC](https://discourse.julialang.org/t/grid-data-with-interpolation/100574 "2023-06-19T21:49:53Z")

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Hi All, I have two equidistant vectors (longitude and time) that make up a “grid” in which I want to plot velocity measurements. The velocity data points have corresponding longitudes and times, however not all of those…

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## [Julia training course costs?](https://discourse.julialang.org/t/julia-training-course-costs/100539)

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**Author:** [@ConnectedSystems](https://discourse.julialang.org/u/ConnectedSystems)\
**Replies:** 6\
**Last updated:** [June 19, 2023, 6:41pm UTC](https://discourse.julialang.org/t/julia-training-course-costs/100539 "2023-06-19T18:41:02Z")

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Hello Julia community! My workplace (based in Australia) is thinking of organising training for staff to learn Julia, specifically machine learning with Julia. Of course, part of the process involves giving a rough cost…

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## [Why is the default behaviour of DifferentialEquations to extrapolate the solution beyond the time range?](https://discourse.julialang.org/t/why-is-the-default-behaviour-of-differentialequations-to-extrapolate-the-solution-beyond-the-time-range/100421)

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**Author:** [@Larbino1](https://discourse.julialang.org/u/Larbino1)\
**Replies:** 3\
**Last updated:** [June 19, 2023, 11:03am UTC](https://discourse.julialang.org/t/why-is-the-default-behaviour-of-differentialequations-to-extrapolate-the-solution-beyond-the-time-range/100421 "2023-06-19T11:03:20Z")

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I just spent an entire afternoon debugging why my equation appears to go unstable. Stupidly, I was animating the solution for T=\[0, 10\], whereas the solution was solved on the interval T=\[0, 3\]. For clarity, my code (fr…

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## [What are the differences between PackageCompiler and BinaryBuilder to build stan-alone apps?](https://discourse.julialang.org/t/what-are-the-differences-between-packagecompiler-and-binarybuilder-to-build-stan-alone-apps/100531)

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**Author:** [@bertulli](https://discourse.julialang.org/u/bertulli)\
**Replies:** 3\
**Last updated:** [June 19, 2023, 9:12am UTC](https://discourse.julialang.org/t/what-are-the-differences-between-packagecompiler-and-binarybuilder-to-build-stan-alone-apps/100531 "2023-06-19T09:12:34Z")

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Hi all! Pretty much the title question, but I’d like to give a bit of context. I’m using Julia to develop my Master’s thesis (love the language so far). I need to integrate a linear model predictor I’m developing into t…

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## [Graph Plot with Custom Nodes](https://discourse.julialang.org/t/graph-plot-with-custom-nodes/100446)

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**Author:** [@flobe](https://discourse.julialang.org/u/flobe)\
**Replies:** 4\
**Last updated:** [June 19, 2023, 8:36am UTC](https://discourse.julialang.org/t/graph-plot-with-custom-nodes/100446 "2023-06-19T08:36:10Z")

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Hi all :slight\_smile: I’m currently working with GraphPlot.jl to visualize my data - works fine. However I want to enrich the visualization so that you can see the confidence of the nodes/data in the graph during the si…

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## [Are there online algorithms to solve/update Neural SDGs solutions incrementally?](https://discourse.julialang.org/t/are-there-online-algorithms-to-solve-update-neural-sdgs-solutions-incrementally/100385)

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**Author:** [@schlichtanders](https://discourse.julialang.org/u/schlichtanders)\
**Replies:** 2\
**Last updated:** [June 19, 2023, 8:09am UTC](https://discourse.julialang.org/t/are-there-online-algorithms-to-solve-update-neural-sdgs-solutions-incrementally/100385 "2023-06-19T08:09:29Z")

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Hi there, I am looking around for online algorithms to fit probablistic models for timeseries data. Neural Stochastic Differential Equations (as a subclass of Universal Differential Equations if I understood it right) s…

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## [Saving heatmap as pdf resolution](https://discourse.julialang.org/t/saving-heatmap-as-pdf-resolution/100499)

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**Author:** [@Peter\_Uhl1](https://discourse.julialang.org/u/Peter_Uhl1)\
**Replies:** 4\
**Last updated:** [June 19, 2023, 7:50am UTC](https://discourse.julialang.org/t/saving-heatmap-as-pdf-resolution/100499 "2023-06-19T07:50:40Z")

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I’m trying to save a simple 100x100 heatmap as a pdf. When I do, the heatmap ends up looking blurry in the saved image. Just doing heatmap(rand(100,100)) savefig("stuff.pdf") saves a pdf with the axis labels, colorbar,…

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## [Is there any way to check the installation time of a package?](https://discourse.julialang.org/t/is-there-any-way-to-check-the-installation-time-of-a-package/100509)

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**Author:** [@WuSiren](https://discourse.julialang.org/u/WuSiren)\
**Replies:** 10\
**Last updated:** [June 19, 2023, 7:44am UTC](https://discourse.julialang.org/t/is-there-any-way-to-check-the-installation-time-of-a-package/100509 "2023-06-19T07:44:32Z")

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I can’t remember under what circumstance I installed a certain package. Is there any way to check its installation time to help me recall that? Besides, when the number of packages grows is there any good solution to man…

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## [Efficient multiplication between a low-rank matrix approximation and a vector](https://discourse.julialang.org/t/efficient-multiplication-between-a-low-rank-matrix-approximation-and-a-vector/100512)

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**Author:** [@danieleavitabile](https://discourse.julialang.org/u/danieleavitabile)\
**Replies:** 6\
**Last updated:** [June 18, 2023, 6:02pm UTC](https://discourse.julialang.org/t/efficient-multiplication-between-a-low-rank-matrix-approximation-and-a-vector/100512 "2023-06-18T18:02:31Z")

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Dear All, I am quite new to Julia, and I am searching for a recommendation. Calling svd(A), I obtain a singular-value decomposition object that gives me access to the U, S, V, as discussed in the documentation. I am in…

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## [CondaPkg error](https://discourse.julialang.org/t/condapkg-error/100523)

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**Author:** [@e3c6](https://discourse.julialang.org/u/e3c6)\
**Replies:** 2\
**Last updated:** [June 18, 2023, 5:59pm UTC](https://discourse.julialang.org/t/condapkg-error/100523 "2023-06-18T17:59:31Z")

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I’ve been getting errors like this lately, from CondaPkg: critical libmamba filesystem error: cannot copy symlink: Operation not permitted \[~/.julia/scratchspaces/0b3b1443-0f03-428d-bdfb-f27f9c1191ea/root/pkgs/libstdcx…

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## [JavaCallError when using Spark.jl](https://discourse.julialang.org/t/javacallerror-when-using-spark-jl/100496)

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**Author:** [@taotree](https://discourse.julialang.org/u/taotree)\
**Replies:** 1\
**Last updated:** [June 18, 2023, 12:41pm UTC](https://discourse.julialang.org/t/javacallerror-when-using-spark-jl/100496 "2023-06-18T12:41:38Z")

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When running using Spark: julia\> using Spark ERROR: InitError: JavaCall.JavaCallError("JULIA\_COPY\_STACKS should not be set on Windows.") Stacktrace: \[1\] assertroottask\_or\_goodenv @ C:\\Users\\joel\\.julia\\packages\\Ja…

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## [Similar MArray with different size](https://discourse.julialang.org/t/similar-marray-with-different-size/100490)

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**Author:** [@nicolas](https://discourse.julialang.org/u/nicolas)\
**Replies:** 7\
**Last updated:** [June 18, 2023, 12:37pm UTC](https://discourse.julialang.org/t/similar-marray-with-different-size/100490 "2023-06-18T12:37:43Z")

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I want to create an array similar to some other array, which could be an Array, a MArray, or some other kind of mutable array-like container. But I would also like to set its dimensions to m×n. I’ve tried similar and it …

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## [Multiple Widgets and Plots (Interact, Plotly)](https://discourse.julialang.org/t/multiple-widgets-and-plots-interact-plotly/100508)

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**Author:** [@StrangePlay](https://discourse.julialang.org/u/StrangePlay)\
**Replies:** 0\
**Last updated:** [June 18, 2023, 7:34am UTC](https://discourse.julialang.org/t/multiple-widgets-and-plots-interact-plotly/100508 "2023-06-18T07:34:48Z")

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Hello folks, Not sure if this is the right place for this question (if not please direct me there). I’m trying to plot 4 plots on a 2 x 2 layout using Interact, Plotly (plotlyjs backend) along with a massive number of …

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