# New to Julia

**URL:** https://discourse.julialang.org/c/first-steps/8.md?page=61

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

**Page:** 62

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## [Multivariate normal distribution?](https://discourse.julialang.org/t/multivariate-normal-distribution/107560)

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**Author:** [@disaster](https://discourse.julialang.org/u/disaster)\
**Replies:** 3\
**Last updated:** [December 13, 2023, 12:32pm UTC](https://discourse.julialang.org/t/multivariate-normal-distribution/107560 "2023-12-13T12:32:39Z")

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Hello, i’m new to Julia and have to plot a multivariate normal distribution. If i use MvNormal and try to plot it like plot(x\_values,MvNormal) I get the Error Cannot convert FullNormal to series data for plotting stacktr…

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## [Static Array With Random Numbers From a Uniform Distribution](https://discourse.julialang.org/t/static-array-with-random-numbers-from-a-uniform-distribution/107513)

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**Author:** [@hakanc](https://discourse.julialang.org/u/hakanc)\
**Replies:** 9\
**Last updated:** [December 13, 2023, 10:56am UTC](https://discourse.julialang.org/t/static-array-with-random-numbers-from-a-uniform-distribution/107513 "2023-12-13T10:56:44Z")

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I am trying to define a static array with numbers pulled from a uniform distribution (using Distributions) from -1 to 1. It is easy to generate a matrix: pvec=rand(Uniform(-1, 1), 3,10) But I want to have a static arra…

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## [Getting ForwardDiff.Dual to propagate through function](https://discourse.julialang.org/t/getting-forwarddiff-dual-to-propagate-through-function/107506)

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**Author:** [@keynescoefen](https://discourse.julialang.org/u/keynescoefen)\
**Replies:** 5\
**Last updated:** [December 13, 2023, 8:01am UTC](https://discourse.julialang.org/t/getting-forwarddiff-dual-to-propagate-through-function/107506 "2023-12-13T08:01:43Z")

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Hello! I would like to automatically differentiate a log-likelihood to obtain gradients and Hessians but have trouble propagating ForwardDiff.Dual types through my function. I have the same questions as here and tried t…

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## [SW engineering books](https://discourse.julialang.org/t/sw-engineering-books/107515)

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**Author:** [@gudyrmik](https://discourse.julialang.org/u/gudyrmik)\
**Replies:** 1\
**Last updated:** [December 12, 2023, 6:48pm UTC](https://discourse.julialang.org/t/sw-engineering-books/107515 "2023-12-12T18:48:39Z")

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Hello everyone, could please someboby reccommend some titles about software engineering using Julia? Design patterns, writing tests (maybe TDD generally), proper architecturing in Julia, etc etc. so, everything around …

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## [Fastest Way to Carry Out Multiple Cross Products](https://discourse.julialang.org/t/fastest-way-to-carry-out-multiple-cross-products/107495)

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**Author:** [@hakanc](https://discourse.julialang.org/u/hakanc)\
**Replies:** 12\
**Last updated:** [December 12, 2023, 5:02pm UTC](https://discourse.julialang.org/t/fastest-way-to-carry-out-multiple-cross-products/107495 "2023-12-12T17:02:48Z")

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Hi everyone, I am moving some code from Matlab to Julia and I need to carry out a large number (N) of cross products (at least ten thousand). In Matlab, I had two 3xN matrices and I could use cross(omega,pmat) to take th…

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## [Includes and loops](https://discourse.julialang.org/t/includes-and-loops/54752)

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**Author:** [@Benoit\_Gaudeul](https://discourse.julialang.org/u/Benoit_Gaudeul)\
**Replies:** 2\
**Last updated:** [December 12, 2023, 4:56pm UTC](https://discourse.julialang.org/t/includes-and-loops/54752 "2023-12-12T16:56:46Z")

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I have defined some code (generation of a mesh) in a file “mesh.jl” that I’m trying to include in an other one. The command include("mesh.jl") worked fine. To draw a convergence curve I tried to use it into a loop and ge…

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## [Load HDF5 file larger than memory](https://discourse.julialang.org/t/load-hdf5-file-larger-than-memory/107412)

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**Author:** [@jisutich](https://discourse.julialang.org/u/jisutich)\
**Replies:** 6\
**Last updated:** [December 12, 2023, 7:27am UTC](https://discourse.julialang.org/t/load-hdf5-file-larger-than-memory/107412 "2023-12-12T07:27:27Z")

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Hi, I am trying to read data from a HDF5 file which is larger than the memory of my computer. I think every time I just need part of data in the file. Is there a way to get part of groups/dataset in the file without loa…

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## [How to input multiple lines in Julia REPL](https://discourse.julialang.org/t/how-to-input-multiple-lines-in-julia-repl/92627)

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**Author:** [@Jack\_Chou](https://discourse.julialang.org/u/Jack_Chou)\
**Replies:** 12\
**Last updated:** [December 12, 2023, 5:17am UTC](https://discourse.julialang.org/t/how-to-input-multiple-lines-in-julia-repl/92627 "2023-12-12T05:17:01Z")

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How to input multiple lines in Julia REPL in Windows System, I try to use Ctrl + Enter, but it doesn’t work.

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## [Why is there a discrepancy in the value of sqrt(2) from Wolfram Alpha and Julia?](https://discourse.julialang.org/t/why-is-there-a-discrepancy-in-the-value-of-sqrt-2-from-wolfram-alpha-and-julia/107461)

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**Author:** [@chandra](https://discourse.julialang.org/u/chandra)\
**Replies:** 5\
**Last updated:** [December 11, 2023, 11:55pm UTC](https://discourse.julialang.org/t/why-is-there-a-discrepancy-in-the-value-of-sqrt-2-from-wolfram-alpha-and-julia/107461 "2023-12-11T23:55:14Z")

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On the Wolfram Alpha website, I get this approximation for sqrt(2) 1.4142135623730950488016887242096980785696718753769480731766797379... With the Julia REPL, I get sqrt(2) 1.4142135623730951 and convert(BigFloat, sq…

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## [Download decompressed .zip-archive from url](https://discourse.julialang.org/t/download-decompressed-zip-archive-from-url/107452)

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**Author:** [@maximikos](https://discourse.julialang.org/u/maximikos)\
**Replies:** 1\
**Last updated:** [December 11, 2023, 6:11pm UTC](https://discourse.julialang.org/t/download-decompressed-zip-archive-from-url/107452 "2023-12-11T18:11:28Z")

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Hi, I would like to extract and download files from a .zip-archive stored online (here) without having to download intermediate files. The .zip-archive consists of .txt and .json files and is nested. I have found two r…

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## [Tutorials/books on C++ Object Oriented methodology to Julia Multiple Dispatch](https://discourse.julialang.org/t/tutorials-books-on-c-object-oriented-methodology-to-julia-multiple-dispatch/107289)

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**Author:** [@PatrickChampion.NCHS](https://discourse.julialang.org/u/PatrickChampion.NCHS)\
**Replies:** 13\
**Last updated:** [December 11, 2023, 3:23pm UTC](https://discourse.julialang.org/t/tutorials-books-on-c-object-oriented-methodology-to-julia-multiple-dispatch/107289 "2023-12-11T15:23:03Z")

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Can someone give like the 5 best Tutorials, whitepapers, or books that clearly describe how to map classic C++ (or Java) object orientation (inheritance, virtual constructor/destructors, polymorphism, and templates) into…

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## [Resources to Understand Distributed.jl](https://discourse.julialang.org/t/resources-to-understand-distributed-jl/107395)

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**Author:** [@bdas123](https://discourse.julialang.org/u/bdas123)\
**Replies:** 5\
**Last updated:** [December 11, 2023, 1:50pm UTC](https://discourse.julialang.org/t/resources-to-understand-distributed-jl/107395 "2023-12-11T13:50:05Z")

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Besides the Distributed.jl documentation, are there any other good resources to understand the theory/application of the library? I’d figure to ask here before I do a deep dive on the topic.

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## [Trouble Enabling Multithreading within Jupyter Notebook](https://discourse.julialang.org/t/trouble-enabling-multithreading-within-jupyter-notebook/107411)

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**Author:** [@bdas123](https://discourse.julialang.org/u/bdas123)\
**Replies:** 5\
**Last updated:** [December 11, 2023, 1:10pm UTC](https://discourse.julialang.org/t/trouble-enabling-multithreading-within-jupyter-notebook/107411 "2023-12-11T13:10:48Z")

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When I execute the following command: using IJulia installkernel("Julia (4 threads)", env=Dict("JULIA\_NUM\_THREADS"=\>"4")) Threads.nthreads() I only get 1 thread. Is there a way to increase the number of threads within …

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## [How i can host my julia api for free](https://discourse.julialang.org/t/how-i-can-host-my-julia-api-for-free/107158)

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**Author:** [@Night\_Xcros](https://discourse.julialang.org/u/Night_Xcros)\
**Replies:** 7\
**Last updated:** [December 11, 2023, 12:29pm UTC](https://discourse.julialang.org/t/how-i-can-host-my-julia-api-for-free/107158 "2023-12-11T12:29:16Z")

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how i can host my julia api for free,is there any unoficioal trick for host it for free

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## [How to know which ContinuedFractions package to use?](https://discourse.julialang.org/t/how-to-know-which-continuedfractions-package-to-use/107381)

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**Author:** [@chandra](https://discourse.julialang.org/u/chandra)\
**Replies:** 2\
**Last updated:** [December 11, 2023, 8:31am UTC](https://discourse.julialang.org/t/how-to-know-which-continuedfractions-package-to-use/107381 "2023-12-11T08:31:44Z")

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I am interested in the ContinuedFractions package in Julia. I found two repositories: ContinuedFractions.jl-One and ContinuedFractions.jl-Two How do I find out which to use? If necessary, how do I uninstall the wro…

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## [Difference between JuliaGPU and Distributed.jl](https://discourse.julialang.org/t/difference-between-juliagpu-and-distributed-jl/107394)

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**Author:** [@bdas123](https://discourse.julialang.org/u/bdas123)\
**Replies:** 2\
**Last updated:** [December 11, 2023, 1:07am UTC](https://discourse.julialang.org/t/difference-between-juliagpu-and-distributed-jl/107394 "2023-12-11T01:07:01Z")

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Hello! This is more of a conceptual question. It seems like Distributed.jl and JuliaGPU.jl both take advantage of parallel operations. I guess what’s the difference? Why use JuilaGPU when Distributed gets the same job …

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## [How to correctly reach a Sagemaker endpoint with AWS.jl](https://discourse.julialang.org/t/how-to-correctly-reach-a-sagemaker-endpoint-with-aws-jl/107380)

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**Author:** [@Simone\_Gabbriellini](https://discourse.julialang.org/u/Simone_Gabbriellini)\
**Replies:** 0\
**Last updated:** [December 10, 2023, 4:26pm UTC](https://discourse.julialang.org/t/how-to-correctly-reach-a-sagemaker-endpoint-with-aws-jl/107380 "2023-12-10T16:26:20Z")

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I am using AWS.jl to call from my machine a Sagemaker endpoint I have on AWS like this: using JSON using AWS: @service @service Sagemaker\_Runtime; body = Dict(:inputs =\> "what is Python?", :parameters =\> Dict( :max\_new…

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## [AWS and sign\_aws4 request made with HTTP](https://discourse.julialang.org/t/aws-and-sign-aws4-request-made-with-http/107370)

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**Author:** [@Simone\_Gabbriellini](https://discourse.julialang.org/u/Simone_Gabbriellini)\
**Replies:** 19\
**Last updated:** [December 10, 2023, 2:29pm UTC](https://discourse.julialang.org/t/aws-and-sign-aws4-request-made-with-http/107370 "2023-12-10T14:29:42Z")

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I am trying to autenticate a request to my AWS endpoint using AWS Signature 4, I see there’s a function in AWS.jl called sign\_aws4!, but I would appreciate a code example of how to use it, because I don’t really understa…

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## [Where do I report possible errors in documentation?](https://discourse.julialang.org/t/where-do-i-report-possible-errors-in-documentation/107375)

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**Author:** [@chandra](https://discourse.julialang.org/u/chandra)\
**Replies:** 3\
**Last updated:** [December 10, 2023, 12:31pm UTC](https://discourse.julialang.org/t/where-do-i-report-possible-errors-in-documentation/107375 "2023-12-10T12:31:53Z")

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“However, despite integration being an algorithmic procedure, integration is not.” at https://docs.juliahub.com/CalculusWithJulia/AZHbv/0.0.5/integrals/partial\_fractions.html# probably should read However, despite d…

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## [Scopes: accessing a global variable hidden by a local of the same name](https://discourse.julialang.org/t/scopes-accessing-a-global-variable-hidden-by-a-local-of-the-same-name/107253)

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**Author:** [@ryofurue](https://discourse.julialang.org/u/ryofurue)\
**Replies:** 17\
**Last updated:** [December 9, 2023, 7:43pm UTC](https://discourse.julialang.org/t/scopes-accessing-a-global-variable-hidden-by-a-local-of-the-same-name/107253 "2023-12-09T19:43:56Z")

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I’m not exactly “new to Julia” but I thought this would belong here. How do you access a global variable hidden by a local variable of the same name? Reading the documentation (see the bottom of this message), I got th…

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## [Error building SymPy and PyCall when username has a space](https://discourse.julialang.org/t/error-building-sympy-and-pycall-when-username-has-a-space/107214)

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**Author:** [@cjslc008](https://discourse.julialang.org/u/cjslc008)\
**Replies:** 6\
**Last updated:** [December 9, 2023, 7:04pm UTC](https://discourse.julialang.org/t/error-building-sympy-and-pycall-when-username-has-a-space/107214 "2023-12-09T19:04:36Z")

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Hi I’m trying to use SymPy and PyCall,but there is an error of a bad installation to both of them.When I use the the command Pkg.build ,it says that there is an error of precompilation as Miniconda doesn’t support the d…

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## [Creating an package (and eventually app) with Python dependencies](https://discourse.julialang.org/t/creating-an-package-and-eventually-app-with-python-dependencies/107317)

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**Author:** [@sadish-d](https://discourse.julialang.org/u/sadish-d)\
**Replies:** 9\
**Last updated:** [December 9, 2023, 6:37pm UTC](https://discourse.julialang.org/t/creating-an-package-and-eventually-app-with-python-dependencies/107317 "2023-12-09T18:37:21Z")

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I’m working on my first package ever in any language. I want to eventually turn this package into an standalone app (using PackageCompiler.jl). I am running into some trouble. My (local) package MyPackage uses a python …

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## [GTK4 DropDown](https://discourse.julialang.org/t/gtk4-dropdown/107359)

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**Author:** [@SergeantMike67](https://discourse.julialang.org/u/SergeantMike67)\
**Replies:** 1\
**Last updated:** [December 9, 2023, 6:28pm UTC](https://discourse.julialang.org/t/gtk4-dropdown/107359 "2023-12-09T18:28:55Z")

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Keeping it simple about Drop Down widget how do you capture the item into a variable for use in a SQL query? how do you put in a list of new items into a previously created Drop Down? These seem like very basic …

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## [Tullio broadcasting issue](https://discourse.julialang.org/t/tullio-broadcasting-issue/107321)

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**Author:** [@swanchristmas](https://discourse.julialang.org/u/swanchristmas)\
**Replies:** 4\
**Last updated:** [December 9, 2023, 11:46am UTC](https://discourse.julialang.org/t/tullio-broadcasting-issue/107321 "2023-12-09T11:46:28Z")

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@tensor tmp1\[m,s,n,p\] := -λ\[l,m,s\]\*ω\[l,k\]\*λ\[k,n,p\] + λ\[l,m,s\]\*g\[l,n\]\*ones(2)\[p\]) @tullio tmp2\[m,s,n,p\] := -λ\[l,m,s\]\*ω\[l,k\]\*λ\[k,n,p\] + λ\[l,m,s\]\*g\[l,n\] tmp1 turns out to be different from tmp2. It seems that @tullio perfo…

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## [Sort indices based on value](https://discourse.julialang.org/t/sort-indices-based-on-value/107299)

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**Author:** [@putianyi888](https://discourse.julialang.org/u/putianyi888)\
**Replies:** 13\
**Last updated:** [December 8, 2023, 7:28pm UTC](https://discourse.julialang.org/t/sort-indices-based-on-value/107299 "2023-12-08T19:28:46Z")

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Is there an existing method that can get a value -\> index map of a vector? For example, something that works like this: function findalls(A::Vector) d = Dict{eltype(A), Vector{Int}}() for (i,v) in enumerate(A) …

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## [How can I view W matrix evaluation times and the W matrices themselves?](https://discourse.julialang.org/t/how-can-i-view-w-matrix-evaluation-times-and-the-w-matrices-themselves/107301)

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**Author:** [@novalex98](https://discourse.julialang.org/u/novalex98)\
**Replies:** 1\
**Last updated:** [December 8, 2023, 7:16pm UTC](https://discourse.julialang.org/t/how-can-i-view-w-matrix-evaluation-times-and-the-w-matrices-themselves/107301 "2023-12-08T19:16:24Z")

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I’m trying to solve a stubbornly unstable nonlinear ODE. When I plot the terms of my ODE its fairly obvious what time step things start to go wrong at. As seen in this graph, everything starts to fall apart at z = 35…

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## [Error when trying to add Pluto to Julia (Mac)](https://discourse.julialang.org/t/error-when-trying-to-add-pluto-to-julia-mac/107126)

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**Author:** [@molinq](https://discourse.julialang.org/u/molinq)\
**Replies:** 23\
**Last updated:** [December 8, 2023, 5:22pm UTC](https://discourse.julialang.org/t/error-when-trying-to-add-pluto-to-julia-mac/107126 "2023-12-08T17:22:59Z")

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Hey guys, I have just downloaded Julia 1.9 on my MacBook and everytime I try to add Pluto to Julia, I get this error message: (@v1.9) pkg\> dyld: Library not loaded: @rpath/libLLVM.dylib Referenced from: /Applications/…

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## [How to preallocate for a parallel monte carlo simulation?](https://discourse.julialang.org/t/how-to-preallocate-for-a-parallel-monte-carlo-simulation/107104)

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**Author:** [@Taneli\_Tolppanen](https://discourse.julialang.org/u/Taneli_Tolppanen)\
**Replies:** 5\
**Last updated:** [December 8, 2023, 8:08am UTC](https://discourse.julialang.org/t/how-to-preallocate-for-a-parallel-monte-carlo-simulation/107104 "2023-12-08T08:08:22Z")

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I am trying to run a series of monte carlo simulations. My simulation gives as an output a matrix. I would like to preallocate this matrix for each of the simulations, and also preallocate some work vectors since I am ru…

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## [Turn a module into a package locally](https://discourse.julialang.org/t/turn-a-module-into-a-package-locally/37370)

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**Author:** [@lewis](https://discourse.julialang.org/u/lewis)\
**Replies:** 43\
**Last updated:** [December 7, 2023, 10:35pm UTC](https://discourse.julialang.org/t/turn-a-module-into-a-package-locally/37370 "2023-12-07T22:35:42Z")

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This topic has been asked many times. I have read many posts. Much of the information is incomplete or contradictory. I have read the package manual. It uses the word “project” in 2 very different senses. So, let’s …

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## [Is there a clean one-liner to subset a vector of vectors?](https://discourse.julialang.org/t/is-there-a-clean-one-liner-to-subset-a-vector-of-vectors/107249)

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**Author:** [@Tetrakai](https://discourse.julialang.org/u/Tetrakai)\
**Replies:** 6\
**Last updated:** [December 7, 2023, 8:34pm UTC](https://discourse.julialang.org/t/is-there-a-clean-one-liner-to-subset-a-vector-of-vectors/107249 "2023-12-07T20:34:30Z")

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I have something like this: julia\> A = \[\[1,\[2,3\]\], \[4,\[5,6\]\], \[7,\[8,9\]\]\] 3-element Vector{Vector{Any}}: \[1, \[2, 3\]\] \[4, \[5, 6\]\] \[7, \[8, 9\]\] julia\> B = \[A\[i\]\[2\]\[1\] for i in 1:length(A)\] 3-element Vector{Int64}: 2 5…

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