# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1729

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

**Page:** 1730

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## [Revise.jl with Distributed and pmap -- why does this behavior not work?](https://discourse.julialang.org/t/revise-jl-with-distributed-and-pmap-why-does-this-behavior-not-work/35944)

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**Author:** [@torgo](https://discourse.julialang.org/u/torgo)\
**Replies:** 6\
**Last updated:** [June 3, 2020, 10:11pm UTC](https://discourse.julialang.org/t/revise-jl-with-distributed-and-pmap-why-does-this-behavior-not-work/35944 "2020-06-03T22:11:55Z")

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\# ModuleA.jl module ModuleA using Distributed function foo() # a = 5 r = pmap((x -\> myid()), fill(1, 10)) end export foo end First I run this: using Distributed addprocs(4) @everywhere push!(LOAD\_PATH, pwd(…

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## [Compile Julia from source with ease in VS Code (even on Windows!)](https://discourse.julialang.org/t/compile-julia-from-source-with-ease-in-vs-code-even-on-windows/35696)

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**Author:** [@davidanthoff](https://discourse.julialang.org/u/davidanthoff)\
**Replies:** 7\
**Last updated:** [June 3, 2020, 8:02pm UTC](https://discourse.julialang.org/t/compile-julia-from-source-with-ease-in-vs-code-even-on-windows/35696 "2020-06-03T20:02:44Z")

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We just merged a devcontainer.json configuration into the Julia repo. This small change should make it much easier to compile and run Julia from source, in particular for folks that run on Windows or users that only occa…

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## [Accelerate solving many matrix problems](https://discourse.julialang.org/t/accelerate-solving-many-matrix-problems/40500)

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**Author:** [@clinton](https://discourse.julialang.org/u/clinton)\
**Replies:** 8\
**Last updated:** [June 3, 2020, 7:17pm UTC](https://discourse.julialang.org/t/accelerate-solving-many-matrix-problems/40500 "2020-06-03T19:17:01Z")

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Say I have a whole lot of independent small matrix problems (posed as regression problems below). Each individual problem is too small for effective CUDA deployment, yet I am wondering if there is an opportunity for subs…

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## [Strictly for fun: TSP images with Julia](https://discourse.julialang.org/t/strictly-for-fun-tsp-images-with-julia/40527)

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**Author:** [@evanfields](https://discourse.julialang.org/u/evanfields)\
**Replies:** 4\
**Last updated:** [June 3, 2020, 6:59pm UTC](https://discourse.julialang.org/t/strictly-for-fun-tsp-images-with-julia/40527 "2020-06-03T18:59:36Z")

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(Because we can’t all be as good as @cormullion, but you gotta start somewhere…) I put together a small personal project to generate TSP-style images in Julia. The classic example is the TSP Mona Lisa, though I should b…

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## [Can a PlotlyJS plot be exported in a form that includes pan/zoom interactivity?](https://discourse.julialang.org/t/can-a-plotlyjs-plot-be-exported-in-a-form-that-includes-pan-zoom-interactivity/40685)

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**Author:** [@klaff](https://discourse.julialang.org/u/klaff)\
**Replies:** 5\
**Last updated:** [June 3, 2020, 6:47pm UTC](https://discourse.julialang.org/t/can-a-plotlyjs-plot-be-exported-in-a-form-that-includes-pan-zoom-interactivity/40685 "2020-06-03T18:47:04Z")

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Hi, I’m using PlotlyJS to explore some lengthy time series data, and it would be great if I could export a plot with the zoom/pan interactivity. I would like to give it to someone who doesn’t have Julia, as a web page t…

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## [Taking gradients when propagating through an ODE solver](https://discourse.julialang.org/t/taking-gradients-when-propagating-through-an-ode-solver/40652)

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**Author:** [@MikeKlocCZ](https://discourse.julialang.org/u/MikeKlocCZ)\
**Replies:** 6\
**Last updated:** [June 3, 2020, 6:45pm UTC](https://discourse.julialang.org/t/taking-gradients-when-propagating-through-an-ode-solver/40652 "2020-06-03T18:45:35Z")

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I need to differentiate parameters of my model (neural network) through an ODE solver. Apparently, DiffEqFlux allows me to do that but it seems that the gradients are computed only if the network parameters enter direct…

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## [Segfault wrapping GNU multiprecision library MPFR](https://discourse.julialang.org/t/segfault-wrapping-gnu-multiprecision-library-mpfr/40066)

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**Author:** [@mzaffalon](https://discourse.julialang.org/u/mzaffalon)\
**Replies:** 7\
**Last updated:** [June 3, 2020, 6:28pm UTC](https://discourse.julialang.org/t/segfault-wrapping-gnu-multiprecision-library-mpfr/40066 "2020-06-03T18:28:56Z")

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I would like to wrap the GNU multiprecision library MPFR to do in-place operations, and I get a segfault on Windows10 (and Julia 1.4.0 and 1.4.1) when running include("test.jl"). The file test.jl (code below) wraps the t…

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## [How to efficiently do a martix multiplication?](https://discourse.julialang.org/t/how-to-efficiently-do-a-martix-multiplication/40669)

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**Author:** [@Julia\_TestLang](https://discourse.julialang.org/u/Julia_TestLang)\
**Replies:** 7\
**Last updated:** [June 3, 2020, 6:25pm UTC](https://discourse.julialang.org/t/how-to-efficiently-do-a-martix-multiplication/40669 "2020-06-03T18:25:43Z")

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Hello! I’m a Julia beginner and I’d like to know is there any way to make this code more memory efficient? function myAllocTest() p = rand(50,1); A = rand(50,50); W = similar(A); D = similar(A); m =…

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## [Sparse to dense matrix](https://discourse.julialang.org/t/sparse-to-dense-matrix/8380)

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**Author:** [@IljaK91](https://discourse.julialang.org/u/IljaK91)\
**Replies:** 15\
**Last updated:** [June 3, 2020, 5:34pm UTC](https://discourse.julialang.org/t/sparse-to-dense-matrix/8380 "2020-06-03T17:34:15Z")

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For some numerical optimization I need to get the inverse of a sparse matrix. How do I compute it efficiently? Julia throws me an error when I try to use either inv() or A\\B and tells me to convert my sparse matrix first…

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## [PlotlyJS example failure](https://discourse.julialang.org/t/plotlyjs-example-failure/40479)

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**Author:** [@Honza9723](https://discourse.julialang.org/u/Honza9723)\
**Replies:** 9\
**Last updated:** [June 3, 2020, 5:19pm UTC](https://discourse.julialang.org/t/plotlyjs-example-failure/40479 "2020-06-03T17:19:03Z")

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Dear All, I would like to ask for help/advice with following problem. Previously, I used PlotlyJS on Julia 1.1.1 for plotting 3D objects. Unfortunately, after upgrading to Julia 1.4.2 (I deleted Atom + Julia and re-inst…

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## [Custom Sampler in Turing.jl](https://discourse.julialang.org/t/custom-sampler-in-turing-jl/40629)

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**Author:** [@bdeonovic](https://discourse.julialang.org/u/bdeonovic)\
**Replies:** 2\
**Last updated:** [June 3, 2020, 4:04pm UTC](https://discourse.julialang.org/t/custom-sampler-in-turing-jl/40629 "2020-06-03T16:04:12Z")

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Lets say I have some Bayesian model for which the full conditional distributions of some of the variables are known in closed form. How can I write the appropriate Gibbs sampler for these variables in Turing.jl? Lets sa…

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## [Wrapping a recursive struct with Clang.jl](https://discourse.julialang.org/t/wrapping-a-recursive-struct-with-clang-jl/40680)

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**Author:** [@KajWiik](https://discourse.julialang.org/u/KajWiik)\
**Replies:** 1\
**Last updated:** [June 3, 2020, 3:38pm UTC](https://discourse.julialang.org/t/wrapping-a-recursive-struct-with-clang-jl/40680 "2020-06-03T15:38:59Z")

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I am trying to wrap a C library containing several recursive structs like this: struct B; typedef struct A { int foo; struct B \*b; } A; typedef struct B { int faa; A \*a; } B; produces wrapper like this # Aut…

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## [How to extend different internal methods based on the module I load?](https://discourse.julialang.org/t/how-to-extend-different-internal-methods-based-on-the-module-i-load/40661)

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**Author:** [@singularitti](https://discourse.julialang.org/u/singularitti)\
**Replies:** 4\
**Last updated:** [June 3, 2020, 3:38pm UTC](https://discourse.julialang.org/t/how-to-extend-different-internal-methods-based-on-the-module-i-load/40661 "2020-06-03T15:38:05Z")

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For example, if I have a function outer that has an internal implementation inner, and I want to extend inner in different modules. module Outer export outer function outer(a, b) # do something print(methods(inne…

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## [How to discretize and solve a 3D Poisson Equation with Dirichlet boundary conditions owing to DifEqOperators](https://discourse.julialang.org/t/how-to-discretize-and-solve-a-3d-poisson-equation-with-dirichlet-boundary-conditions-owing-to-difeqoperators/40681)

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**Author:** [@RenaudV](https://discourse.julialang.org/u/RenaudV)\
**Replies:** 0\
**Last updated:** [June 3, 2020, 3:24pm UTC](https://discourse.julialang.org/t/how-to-discretize-and-solve-a-3d-poisson-equation-with-dirichlet-boundary-conditions-owing-to-difeqoperators/40681 "2020-06-03T15:24:02Z")

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I love the following example of solving a 1D Poisson equation with DiffEqOperators. However , I struggle to do the analog 3D example. Can somebody indicate me the right steps? using DiffEqOperators, Plots #Poisson Eq …

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## [The right mental model of \`@threads\`?](https://discourse.julialang.org/t/the-right-mental-model-of-threads/40651)

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**Author:** [@scheidan](https://discourse.julialang.org/u/scheidan)\
**Replies:** 6\
**Last updated:** [June 3, 2020, 2:32pm UTC](https://discourse.julialang.org/t/the-right-mental-model-of-threads/40651 "2020-06-03T14:32:40Z")

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Hi, After reading this blog about multi-threading I’ve tried to parallelize a recursive algorithm. The problem is that it used modifying functions and the docs warn us that “we might get a wrong answer”. And indeed, in …

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## [Correct way to include a Distributed workflow in a module](https://discourse.julialang.org/t/correct-way-to-include-a-distributed-workflow-in-a-module/40672)

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**Author:** [@ianshmean](https://discourse.julialang.org/u/ianshmean)\
**Replies:** 0\
**Last updated:** [June 3, 2020, 2:18pm UTC](https://discourse.julialang.org/t/correct-way-to-include-a-distributed-workflow-in-a-module/40672 "2020-06-03T14:18:10Z")

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I want to produce a private package that fully manages and runs a series of distributed processes on private workers, but I’m seeing unstable code loading & scope issues. The kind of approach below errors most of the tim…

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## [Refactoring Clang - could this benefit Julia?](https://discourse.julialang.org/t/refactoring-clang-could-this-benefit-julia/40621)

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**Author:** [@awarzynski](https://discourse.julialang.org/u/awarzynski)\
**Replies:** 2\
**Last updated:** [June 3, 2020, 2:00pm UTC](https://discourse.julialang.org/t/refactoring-clang-could-this-benefit-julia/40621 "2020-06-03T14:00:02Z")

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I’m new to this community so first of all, Hi everyone! I am a member of the Fortran Team at Arm and would like to draw your attention to the RFC that our team has sent today to llvm-dev/cfe-dev/flang-dev: \[llvm-dev\] \[R…

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## [Animation from data points (arrays)](https://discourse.julialang.org/t/animation-from-data-points-arrays/40642)

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**Author:** [@Joey](https://discourse.julialang.org/u/Joey)\
**Replies:** 4\
**Last updated:** [June 3, 2020, 12:24pm UTC](https://discourse.julialang.org/t/animation-from-data-points-arrays/40642 "2020-06-03T12:24:48Z")

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Hello, everyone. I recently switched from MATLAB to Julia, and I do not know a lot of stuff about plotting in Julia. It is a really simple problem yet unclear to me: I need to build a 3d animation out of a set of data p…

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## [From LaTeX to Julia](https://discourse.julialang.org/t/from-latex-to-julia/32485)

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**Author:** [@IljaK91](https://discourse.julialang.org/u/IljaK91)\
**Replies:** 10\
**Last updated:** [June 3, 2020, 11:30am UTC](https://discourse.julialang.org/t/from-latex-to-julia/32485 "2020-06-03T11:30:37Z")

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Hey everyone, my current workflow consists of writing my paper in LyX and then copying the formulas to Julia. This is however often prone to errors. Ideally, I would like to copy my equation from Latex directly to Julia…

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## [How to access columns in a Vector{Array{Float64,2}}](https://discourse.julialang.org/t/how-to-access-columns-in-a-vector-array-float64-2/40659)

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**Author:** [@HelgavonLichtenstein](https://discourse.julialang.org/u/HelgavonLichtenstein)\
**Replies:** 2\
**Last updated:** [June 3, 2020, 11:13am UTC](https://discourse.julialang.org/t/how-to-access-columns-in-a-vector-array-float64-2/40659 "2020-06-03T11:13:40Z")

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I have a Vector{Array{Float64,2}} that I want to access columns from, but I don’t know how. It is generated via comprehension. Does it need to be turned into a DataFrame? If so, how? When I try df1 = DataFrames(one\_foodw…

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## [Something like C++ static declaration for functions in Julia?](https://discourse.julialang.org/t/something-like-c-static-declaration-for-functions-in-julia/40631)

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**Author:** [@Bogo](https://discourse.julialang.org/u/Bogo)\
**Replies:** 15\
**Last updated:** [June 3, 2020, 11:13am UTC](https://discourse.julialang.org/t/something-like-c-static-declaration-for-functions-in-julia/40631 "2020-06-03T11:13:23Z")

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Hi everyone! I was trying to implement a few simple algorithms in Julia, and now have a question about declaring functions static. Minimal example: function myfun(u::Vector{Float64}, param::NTuple{3,Float64}) A1=#do st…

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## [Could not load library "libanco-ratip2013.so" The specified module could not be found](https://discourse.julialang.org/t/could-not-load-library-libanco-ratip2013-so-the-specified-module-could-not-be-found/35415)

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**Author:** [@Mehran\_Baki](https://discourse.julialang.org/u/Mehran_Baki)\
**Replies:** 8\
**Last updated:** [June 3, 2020, 10:59am UTC](https://discourse.julialang.org/t/could-not-load-library-libanco-ratip2013-so-the-specified-module-could-not-be-found/35415 "2020-06-03T10:59:43Z")

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I have a problem with opening a library using JuliaPro\_v1.3.1-1 on Windows 10. the error is “could not load library “C:\\Users\\username.juliapro\\JuliaPro\_v1.3.1-1\\packages\\JAC\\ztL1S\\deps\\bin\\libanco-ratip2013.so” The spec…

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## [PkgAuthentication](https://discourse.julialang.org/t/pkgauthentication/40548)

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**Author:** [@stv1314](https://discourse.julialang.org/u/stv1314)\
**Replies:** 5\
**Last updated:** [June 3, 2020, 10:18am UTC](https://discourse.julialang.org/t/pkgauthentication/40548 "2020-06-03T10:18:36Z")

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## [How to name a dataframe based on a value in a comprehension list](https://discourse.julialang.org/t/how-to-name-a-dataframe-based-on-a-value-in-a-comprehension-list/40655)

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**Author:** [@HelgavonLichtenstein](https://discourse.julialang.org/u/HelgavonLichtenstein)\
**Replies:** 1\
**Last updated:** [June 3, 2020, 9:24am UTC](https://discourse.julialang.org/t/how-to-name-a-dataframe-based-on-a-value-in-a-comprehension-list/40655 "2020-06-03T09:24:33Z")

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Hello, is there a way to name a dataframe using the value of x in a comprehension list? I hoped using $variable\_I\_am\_interested would take the value of that variable and put it into the name, similar to using $ in a stri…

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## [Contours with equal area changing system](https://discourse.julialang.org/t/contours-with-equal-area-changing-system/40644)

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**Author:** [@Tamuzd](https://discourse.julialang.org/u/Tamuzd)\
**Replies:** 3\
**Last updated:** [June 3, 2020, 9:03am UTC](https://discourse.julialang.org/t/contours-with-equal-area-changing-system/40644 "2020-06-03T09:03:39Z")

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Let’s say I have a system with 3 particles in 2d system a,b,c with the following positions a = \[0.1,0.0\] b = \[-0.1,0.0\] c = \[0.0,0.1\] each particle is described by Gaussian function, therefore the system function is as…

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## [Free GPU resources?](https://discourse.julialang.org/t/free-gpu-resources/40653)

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**Author:** [@Ferran\_Mazzanti](https://discourse.julialang.org/u/Ferran_Mazzanti)\
**Replies:** 1\
**Last updated:** [June 3, 2020, 8:54am UTC](https://discourse.julialang.org/t/free-gpu-resources/40653 "2020-06-03T08:54:07Z")

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Hi, I’m running the same Julia code using CuArrays etc in two machines, one at home and one at work. At home my code works well, this is a 16Gb RAM, Ubuntu 18.04 linux box with a Geoforce 1050Ti, 4Gb RAM. On the compute…

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## [From zero to Julia! Learn how to code in Julia](https://discourse.julialang.org/t/from-zero-to-julia-learn-how-to-code-in-julia/33595)

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**Author:** [@aurelio-amerio](https://discourse.julialang.org/u/aurelio-amerio)\
**Replies:** 11\
**Last updated:** [June 3, 2020, 8:32am UTC](https://discourse.julialang.org/t/from-zero-to-julia-learn-how-to-code-in-julia/33595 "2020-06-03T08:32:12Z")

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Hello! In the past few months I’ve been writing a series of introductory lessons to the Julia language. They cover the basics of Julia and gradually move on to more advanced topics, including plotting, parallel computing…

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## [Collection of Examples and Packages ready for App (executables) creation](https://discourse.julialang.org/t/collection-of-examples-and-packages-ready-for-app-executables-creation/40648)

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**Author:** [@uwechsler](https://discourse.julialang.org/u/uwechsler)\
**Replies:** 0\
**Last updated:** [June 3, 2020, 7:51am UTC](https://discourse.julialang.org/t/collection-of-examples-and-packages-ready-for-app-executables-creation/40648 "2020-06-03T07:51:10Z")

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After watching the Webinar on the PackagCompiler and skimming through the documentation, I am really excited about the progress made towards creating an executable from a Julia module. From my understanding, once conditi…

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## [Organisation into submodules and multiple dispatch](https://discourse.julialang.org/t/organisation-into-submodules-and-multiple-dispatch/40641)

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**Author:** [@sparrowhawk](https://discourse.julialang.org/u/sparrowhawk)\
**Replies:** 7\
**Last updated:** [June 3, 2020, 6:15am UTC](https://discourse.julialang.org/t/organisation-into-submodules-and-multiple-dispatch/40641 "2020-06-03T06:15:29Z")

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I want to have a supermodule that contains a function, which carries out different operations depending on the input type. Depending on the type, this function is defined in various submodules. The submodules can be supe…

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## [How to make a wind rose in Julia](https://discourse.julialang.org/t/how-to-make-a-wind-rose-in-julia/40229)

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**Author:** [@scone](https://discourse.julialang.org/u/scone)\
**Replies:** 22\
**Last updated:** [June 3, 2020, 6:10am UTC](https://discourse.julialang.org/t/how-to-make-a-wind-rose-in-julia/40229 "2020-06-03T06:10:05Z")

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Hi, I am trying to just make a wind rose. Its a pretty basic thing, and I can’t find any implementation of it in Julia. The closest I have come is to use the plotlyjs backend, but I can’t figure out how to reverse a…

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