# Latest

**URL:** https://discourse.julialang.org/latest.md?page=582

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

**Page:** 583

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## [Fastest way possible to find index of value equals 1 across a matrix column](https://discourse.julialang.org/t/fastest-way-possible-to-find-index-of-value-equals-1-across-a-matrix-column/104485)

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**Author:** [@eduardosalaz](https://discourse.julialang.org/u/eduardosalaz)\
**Replies:** 7\
**Last updated:** [October 6, 2023, 4:32pm UTC](https://discourse.julialang.org/t/fastest-way-possible-to-find-index-of-value-equals-1-across-a-matrix-column/104485 "2023-10-06T16:32:06Z")

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Hi there everyone. I am currently working on my thesis which involves an optimization problem in which I have an X decision matrix filled with 0s, each column must have a 1 value as it represents an allocation. In my lo…

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## [How to make this custom median for color images faster](https://discourse.julialang.org/t/how-to-make-this-custom-median-for-color-images-faster/104651)

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**Author:** [@Rakesh](https://discourse.julialang.org/u/Rakesh)\
**Replies:** 2\
**Last updated:** [October 6, 2023, 3:47pm UTC](https://discourse.julialang.org/t/how-to-make-this-custom-median-for-color-images-faster/104651 "2023-10-06T15:47:00Z")

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I have made custom median filter for color images, but it performs slow and takes high memory compared to OpenCV.medianBlur. Here is code using ImageIO using FileIO using ImageFiltering using ImageCore # using Statistic…

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## [What should be the mental model of computers for new Julia devs/ software devs in general?](https://discourse.julialang.org/t/what-should-be-the-mental-model-of-computers-for-new-julia-devs-software-devs-in-general/104488)

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**Author:** [@Tarny\_GG\_Channie](https://discourse.julialang.org/u/Tarny_GG_Channie)\
**Replies:** 8\
**Last updated:** [October 6, 2023, 3:05pm UTC](https://discourse.julialang.org/t/what-should-be-the-mental-model-of-computers-for-new-julia-devs-software-devs-in-general/104488 "2023-10-06T15:05:44Z")

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This post is thought-provoking, yet what this post entails is not trivial at all… I understand that some courses make students see computers as single-cycle processors with no cache and single-cycle memory allocator. …

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## [Estimate memory requirements of ODE solver](https://discourse.julialang.org/t/estimate-memory-requirements-of-ode-solver/104567)

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**Author:** [@Salmon](https://discourse.julialang.org/u/Salmon)\
**Replies:** 7\
**Last updated:** [October 6, 2023, 2:57pm UTC](https://discourse.julialang.org/t/estimate-memory-requirements-of-ode-solver/104567 "2023-10-06T14:57:02Z")

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Hi everyone, I am solving a very large (~10^8) system of ODE’s. I would like to use the VCABM solver from ordinaryDiffEq since that seems to be fastest, but I have memory issues that I would like to understand better. I…

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## [Writing dataframe to arrow format with column metadata](https://discourse.julialang.org/t/writing-dataframe-to-arrow-format-with-column-metadata/104407)

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**Author:** [@alicepiller](https://discourse.julialang.org/u/alicepiller)\
**Replies:** 6\
**Last updated:** [October 6, 2023, 11:33am UTC](https://discourse.julialang.org/t/writing-dataframe-to-arrow-format-with-column-metadata/104407 "2023-10-06T11:33:08Z")

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I’m trying to write a dataframe to an arrow file and include column metadata. The code below runs, but example\_metadata has none of the metadata. using Arrow using DataFrames df = DataFrame(x = \[1, 2, 3\], y = \[4, 5, 6…

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## [Any good resource to understand the issues with recursion in Julia?](https://discourse.julialang.org/t/any-good-resource-to-understand-the-issues-with-recursion-in-julia/104615)

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**Author:** [@bguillen](https://discourse.julialang.org/u/bguillen)\
**Replies:** 11\
**Last updated:** [October 6, 2023, 11:20am UTC](https://discourse.julialang.org/t/any-good-resource-to-understand-the-issues-with-recursion-in-julia/104615 "2023-10-06T11:20:49Z")

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I’m implementing basically the Median of Medians (actually, Median of Ninthers) algorithm for quick deterministic selection (see \[original post\]). It is recursive, as in the way to find a pivot is by calculating the medi…

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## [How to write a unit test that checks whether a function is type stable](https://discourse.julialang.org/t/how-to-write-a-unit-test-that-checks-whether-a-function-is-type-stable/104587)

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**Author:** [@CFBaptista](https://discourse.julialang.org/u/CFBaptista)\
**Replies:** 23\
**Last updated:** [October 6, 2023, 11:07am UTC](https://discourse.julialang.org/t/how-to-write-a-unit-test-that-checks-whether-a-function-is-type-stable/104587 "2023-10-06T11:07:18Z")

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I want to write unit tests that check whether a function is type stable. What is currently the most recommendable way to do this? There is an old post on this subject which mentions the Traceur.jl and TraceCalls.jl pac…

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## [Julia potential for high energy physics computing](https://discourse.julialang.org/t/julia-potential-for-high-energy-physics-computing/99992)

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**Author:** [@grasph](https://discourse.julialang.org/u/grasph)\
**Replies:** 3\
**Last updated:** [October 6, 2023, 9:50am UTC](https://discourse.julialang.org/t/julia-potential-for-high-energy-physics-computing/99992 "2023-10-06T09:50:11Z")

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Hello, On behalf of its authors, I would like to announce the following preprint released last night, Potential of the Julia programming language for high energy physics computing, J. Eschle et al., arXiv:2306.03675 T…

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## [Considering static files in PkgTemplates.jl](https://discourse.julialang.org/t/considering-static-files-in-pkgtemplates-jl/104652)

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**Author:** [@Anton\_Hinneck](https://discourse.julialang.org/u/Anton_Hinneck)\
**Replies:** 0\
**Last updated:** [October 6, 2023, 9:24am UTC](https://discourse.julialang.org/t/considering-static-files-in-pkgtemplates-jl/104652 "2023-10-06T09:24:31Z")

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I am working on a Julia template that needs static files for containerization and deployment. ./templates/ looks as follows: src test docs deployment .gitlab-ci.yml LICENSE script.jl … The problem I found is that…

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## [Configurations.jl Option Type with StaticArrays.jl](https://discourse.julialang.org/t/configurations-jl-option-type-with-staticarrays-jl/104640)

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**Author:** [@matthew3245](https://discourse.julialang.org/u/matthew3245)\
**Replies:** 6\
**Last updated:** [October 6, 2023, 7:46am UTC](https://discourse.julialang.org/t/configurations-jl-option-type-with-staticarrays-jl/104640 "2023-10-06T07:46:56Z")

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I’m trying to use Configuration.jl to load a TOML config file into an option structure with StaticVectors or Floats. There are two approaches I’ve used so far to try and achieve this, however, they both have terrible per…

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## [Writing Turing.jl model to avoid loops?](https://discourse.julialang.org/t/writing-turing-jl-model-to-avoid-loops/104593)

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**Author:** [@dleather](https://discourse.julialang.org/u/dleather)\
**Replies:** 2\
**Last updated:** [October 6, 2023, 7:39am UTC](https://discourse.julialang.org/t/writing-turing-jl-model-to-avoid-loops/104593 "2023-10-06T07:39:37Z")

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I’m trying to estimate an 2-dimension Multivariate Ornstein-Uhlenbeck process in Turing.jl using the NUTS algorithm. The solution to this model involves the computation of a matrix exponential. As far as I can deduce, t…

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## [Turing's summary statistics - ESS](https://discourse.julialang.org/t/turings-summary-statistics-ess/103537)

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**Author:** [@PrimulaBunce](https://discourse.julialang.org/u/PrimulaBunce)\
**Replies:** 2\
**Last updated:** [October 6, 2023, 7:35am UTC](https://discourse.julialang.org/t/turings-summary-statistics-ess/103537 "2023-10-06T07:35:31Z")

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Hi, I’m new to MCMC, and I’m using the Turing package to implement NUTS. par\_NUTS = sample(model, NUTS(1000, 0.65), MCMCThreads(), 1000, 3) I’m trying to figure out what the Effective Sample Size (ESS) values returned…

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## [Disease Modeling Specialist (Epidemic Modeling)](https://discourse.julialang.org/t/disease-modeling-specialist-epidemic-modeling/104647)

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**Author:** [@ChrisRackauckas](https://discourse.julialang.org/u/ChrisRackauckas)\
**Replies:** 0\
**Last updated:** [October 6, 2023, 6:48am UTC](https://discourse.julialang.org/t/disease-modeling-specialist-epidemic-modeling/104647 "2023-10-06T06:48:45Z")

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Posting for a friend:

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## [Code uses excessive memory when using \`\`\`.+\`\`\` instead of a loop?](https://discourse.julialang.org/t/code-uses-excessive-memory-when-using-instead-of-a-loop/104624)

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**Author:** [@felipeh](https://discourse.julialang.org/u/felipeh)\
**Replies:** 3\
**Last updated:** [October 6, 2023, 3:13am UTC](https://discourse.julialang.org/t/code-uses-excessive-memory-when-using-instead-of-a-loop/104624 "2023-10-06T03:13:59Z")

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In debugging some code I wrote, I noticed that there seems to be a significant difference between x = x .+ 1 and writing the loop out explicitly. In particular, the following code runs in 0.006 seconds and reports only …

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## [Hot to maintain equal plot sizes of subplot when using e.g. \`legend=:outertop\`?](https://discourse.julialang.org/t/hot-to-maintain-equal-plot-sizes-of-subplot-when-using-e-g-legend-outertop/104637)

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**Author:** [@Torkel](https://discourse.julialang.org/u/Torkel)\
**Replies:** 0\
**Last updated:** [October 5, 2023, 11:48pm UTC](https://discourse.julialang.org/t/hot-to-maintain-equal-plot-sizes-of-subplot-when-using-e-g-legend-outertop/104637 "2023-10-05T23:48:29Z")

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MWE: using Plots p1 = plot(x-\>x^2, label = "my curve") plot(x-\>x^1, label = "A curve") plot!(x-\>x^1, label = "Curve 1") plot!(x-\>x^2, label = "Curve 2") plot!(x-\>x^3, label = "Curve 3") plot!(x-\>x^4, label = "Curve 4") …

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## [Postdoc at Los Alamos National Laboratory](https://discourse.julialang.org/t/postdoc-at-los-alamos-national-laboratory/104636)

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**Author:** [@omalled](https://discourse.julialang.org/u/omalled)\
**Replies:** 0\
**Last updated:** [October 5, 2023, 10:33pm UTC](https://discourse.julialang.org/t/postdoc-at-los-alamos-national-laboratory/104636 "2023-10-05T22:33:42Z")

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I’m looking to hire a postdoc working on computational modeling of subsurface flow and transport related to one of the Department of Energy’s Earthshot projects. Someone with Julia experience would be great. You can appl…

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## [Functions: What can I know? What may I hope for?](https://discourse.julialang.org/t/functions-what-can-i-know-what-may-i-hope-for/104628)

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**Author:** [@laborg](https://discourse.julialang.org/u/laborg)\
**Replies:** 3\
**Last updated:** [October 5, 2023, 7:23pm UTC](https://discourse.julialang.org/t/functions-what-can-i-know-what-may-i-hope-for/104628 "2023-10-05T19:23:06Z")

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In Julia many packages add methods to well known existing functions. My simple question: How to decide whether to reuse an existing name as to come up with a new one? An example: In DataStructures.jl there is a MutableL…

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## [How to Create a 3D-Transparent Cylinder with GLMakie or Plots if possible?](https://discourse.julialang.org/t/how-to-create-a-3d-transparent-cylinder-with-glmakie-or-plots-if-possible/92099)

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**Author:** [@Freya\_the\_Goddess](https://discourse.julialang.org/u/Freya_the_Goddess)\
**Replies:** 9\
**Last updated:** [October 5, 2023, 6:57pm UTC](https://discourse.julialang.org/t/how-to-create-a-3d-transparent-cylinder-with-glmakie-or-plots-if-possible/92099 "2023-10-05T18:57:16Z")

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Hi all, I created this sphere with GL Makie: using GLMakie n = 20 θ = \[0;(0.5:n-0.5)/n;1\] φ = \[(0:2n-2)\*2/(2n-1);2\] x = \[cospi(φ)\*sinpi(θ) for θ in θ, φ in φ\] y = \[sinpi(φ)\*sinpi(θ) for θ in θ, φ in φ\] z = \[cospi(θ)…

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## [Weird matrix multiplication results from MKL](https://discourse.julialang.org/t/weird-matrix-multiplication-results-from-mkl/104623)

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**Author:** [@jacques1](https://discourse.julialang.org/u/jacques1)\
**Replies:** 2\
**Last updated:** [October 5, 2023, 6:32pm UTC](https://discourse.julialang.org/t/weird-matrix-multiplication-results-from-mkl/104623 "2023-10-05T18:32:29Z")

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Hi, I’m trying to use a simple OLS solution to an overdetermined linear system using MKL and LinearAlgebra, with coefficient matrix ‘’’ M = \[200000 0 0 (2e5)^2 0; 0 0 0 0 0; 0 0 0 0 0; 0 0 0 0 0; 0 2e5 0 0 (2e5)^2; 0 0…

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## [Mongoc and DataFrames](https://discourse.julialang.org/t/mongoc-and-dataframes/104622)

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**Author:** [@ginger\_snaps](https://discourse.julialang.org/u/ginger_snaps)\
**Replies:** 0\
**Last updated:** [October 5, 2023, 5:48pm UTC](https://discourse.julialang.org/t/mongoc-and-dataframes/104622 "2023-10-05T17:48:24Z")

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Hello, I work with mongo and financial data and I need to read data from csv write it to mongo get from mongo DataFrame dataframe as I just read it from csv file (types, etc) I wrote some function for that using Mong…

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## [Strange allocation in loop when calling function](https://discourse.julialang.org/t/strange-allocation-in-loop-when-calling-function/104620)

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**Author:** [@GrantHecht](https://discourse.julialang.org/u/GrantHecht)\
**Replies:** 2\
**Last updated:** [October 5, 2023, 5:35pm UTC](https://discourse.julialang.org/t/strange-allocation-in-loop-when-calling-function/104620 "2023-10-05T17:35:52Z")

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Hello! I’ve been working on writing some very simple ODE solvers as an exercise to improve my understanding of Julia and how it can be used to write fast code. In doing so, I’ve arrived at some code that exhibits some s…

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## [\[ANN\] Two new packages for metrics in statistics and ML](https://discourse.julialang.org/t/ann-two-new-packages-for-metrics-in-statistics-and-ml/104374)

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**Author:** [@ablaom](https://discourse.julialang.org/u/ablaom)\
**Replies:** 1\
**Last updated:** [October 5, 2023, 4:47pm UTC](https://discourse.julialang.org/t/ann-two-new-packages-for-metrics-in-statistics-and-ml/104374 "2023-10-05T16:47:09Z")

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I am pleased to announce two new packages for measures (aka metrics) for statistics and machine learning: Build complex measures with StatisticalMeasuresBase.jl Use StatisticalMeasuresBase.jl to quickly build production…

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## [How to use the transform function on data frames](https://discourse.julialang.org/t/how-to-use-the-transform-function-on-data-frames/104582)

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**Author:** [@RobertTalbert](https://discourse.julialang.org/u/RobertTalbert)\
**Replies:** 6\
**Last updated:** [October 5, 2023, 4:01pm UTC](https://discourse.julialang.org/t/how-to-use-the-transform-function-on-data-frames/104582 "2023-10-05T16:01:21Z")

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I apologize for a very low-level question but I’ve just started learning the language and getting stumped. I am trying to take a dataframe and create a new column that’s the average of two other columns. I understand tha…

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## [Interpolate across arc length for constant distances between points](https://discourse.julialang.org/t/interpolate-across-arc-length-for-constant-distances-between-points/104520)

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**Author:** [@modifiedbear](https://discourse.julialang.org/u/modifiedbear)\
**Replies:** 1\
**Last updated:** [October 5, 2023, 2:47pm UTC](https://discourse.julialang.org/t/interpolate-across-arc-length-for-constant-distances-between-points/104520 "2023-10-05T14:47:07Z")

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Is there a way to divide a discretized curve (or a set of points) into another where the segments are of equal length? For example, in Matlab I can do the following to get an ellipse with equispaced points or discretiza…

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## [Micro-benchmark](https://discourse.julialang.org/t/micro-benchmark/104588)

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**Author:** [@lewis](https://discourse.julialang.org/u/lewis)\
**Replies:** 7\
**Last updated:** [October 5, 2023, 6:14am UTC](https://discourse.julialang.org/t/micro-benchmark/104588 "2023-10-05T06:14:06Z")

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Here is a micro-benchmark of Julia, Nim, sbcl, Gambit-Scheme, and Racket for summing a vector of floating point values. Not really any feedback for Julia: this doesn’t warrant finding any extra performance tricks for Ju…

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## [OpinionatedJulia Package?](https://discourse.julialang.org/t/opinionatedjulia-package/103522)

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**Author:** [@mrufsvold](https://discourse.julialang.org/u/mrufsvold)\
**Replies:** 16\
**Last updated:** [October 5, 2023, 7:02am UTC](https://discourse.julialang.org/t/opinionatedjulia-package/103522 "2023-10-05T07:02:09Z")

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I’ve read a lot of opinions about what should be default for Julia to make it more accessible. Some conflicting but a lot of it is in alignment. Some of it is breaking to be in Base. Some of it is a matter of network/com…

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## [One Does Not Simply Walk Into Mordor: Julia, the last language?](https://discourse.julialang.org/t/one-does-not-simply-walk-into-mordor-julia-the-last-language/104544)

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**Author:** [@algunion](https://discourse.julialang.org/u/algunion)\
**Replies:** 4\
**Last updated:** [October 5, 2023, 12:46am UTC](https://discourse.julialang.org/t/one-does-not-simply-walk-into-mordor-julia-the-last-language/104544 "2023-10-05T00:46:12Z")

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Just wanted to let you all know that one does not simply give up Julia. I attempted to do this without being able to evaluate in advance how hooked my brain became on multiple dispatch. With some effort, I can compensat…

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## [CEnum v0.4.2 unavailable from us-east.pkg.julialang.org](https://discourse.julialang.org/t/cenum-v0-4-2-unavailable-from-us-east-pkg-julialang-org/104584)

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**Author:** [@Samuel\_Stapleton](https://discourse.julialang.org/u/Samuel_Stapleton)\
**Replies:** 3\
**Last updated:** [October 5, 2023, 1:40pm UTC](https://discourse.julialang.org/t/cenum-v0-4-2-unavailable-from-us-east-pkg-julialang-org/104584 "2023-10-05T13:40:40Z")

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Requesting CEnum v0.4.2 from us-west results in a 200 status: https://us-west.pkg.julialang.org/package/fa961155-64e5-5f13-b03f-caf6b980ea82/eb4cb44a499229b3b8426dcfb5dd85333951ff90 However, requesting from us-east res…

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## [About Start Values in JuMP - MOA](https://discourse.julialang.org/t/about-start-values-in-jump-moa/104500)

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**Author:** [@rodolforbcoutinho](https://discourse.julialang.org/u/rodolforbcoutinho)\
**Replies:** 6\
**Last updated:** [October 5, 2023, 1:39pm UTC](https://discourse.julialang.org/t/about-start-values-in-jump-moa/104500 "2023-10-05T13:39:54Z")

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Hello to all! I have a doubt about using start values in variables. My hypothesis was that could speed up the execution time if I provide most of the values in variable vector already in optimum position. In my proble…

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## [Struggling with creating a faster threaded version of a concurrent problem](https://discourse.julialang.org/t/struggling-with-creating-a-faster-threaded-version-of-a-concurrent-problem/104549)

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**Author:** [@tamasgal](https://discourse.julialang.org/u/tamasgal)\
**Replies:** 16\
**Last updated:** [October 5, 2023, 12:22pm UTC](https://discourse.julialang.org/t/struggling-with-creating-a-faster-threaded-version-of-a-concurrent-problem/104549 "2023-10-05T12:22:56Z")

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Alright, I am so desperate that I call for some help from people experienced in concurrent/threaded programming in Julia since I am hitting a wall here. I can’t even provide a MWE but I am getting more and more desperate…

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