# General Usage

**URL:** https://discourse.julialang.org/c/usage/6.md?page=59

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**Page:** 60

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## [Cycling categorical color scale for unlimited unique values in Makie?](https://discourse.julialang.org/t/cycling-categorical-color-scale-for-unlimited-unique-values-in-makie/129578)

<div class="topic-metadata">

**Author:** [@oscarvdvelde](https://discourse.julialang.org/u/oscarvdvelde)\
**Replies:** 4\
**Last updated:** [June 7, 2025, 12:29pm UTC](https://discourse.julialang.org/t/cycling-categorical-color-scale-for-unlimited-unique-values-in-makie/129578 "2025-06-07T12:29:27Z")

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I am looking for a solution for a color map in Makie, for groups of points that need to be colored by their integer values (e.g. group number). There may be hundreds of unique values, so one can not see any visual differ…

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## [Large number of memory allocations using Dict with custom key type](https://discourse.julialang.org/t/large-number-of-memory-allocations-using-dict-with-custom-key-type/129676)

<div class="topic-metadata">

**Author:** [@erenust](https://discourse.julialang.org/u/erenust)\
**Replies:** 10\
**Last updated:** [June 7, 2025, 11:13am UTC](https://discourse.julialang.org/t/large-number-of-memory-allocations-using-dict-with-custom-key-type/129676 "2025-06-07T11:13:39Z")

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As part of the code I’m working on I need to find the unique elements of a collection of small integer arrays and assign a unique identifier to each one of them. To do this I could do something like the following: array…

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## [New String7 type from result of CSV.file|\>DataFrame makes my function failing (which takes a String as input)](https://discourse.julialang.org/t/new-string7-type-from-result-of-csv-file-dataframe-makes-my-function-failing-which-takes-a-string-as-input/68985)

<div class="topic-metadata">

**Author:** [@jdad](https://discourse.julialang.org/u/jdad)\
**Replies:** 10\
**Last updated:** [June 7, 2025, 7:13am UTC](https://discourse.julialang.org/t/new-string7-type-from-result-of-csv-file-dataframe-makes-my-function-failing-which-takes-a-string-as-input/68985 "2025-06-07T07:13:37Z")

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My script used to work till yesterday, but is now failing because of the following error ERROR: LoadError: MethodError: no method matching get\_symbols\_ta(::String7, ::String, ::String) Closest candidates are: get\_symb…

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## [PETSC.jl MPI wrapper](https://discourse.julialang.org/t/petsc-jl-mpi-wrapper/77900)

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**Author:** [@Srikumar](https://discourse.julialang.org/u/Srikumar)\
**Replies:** 8\
**Last updated:** [June 7, 2025, 3:23am UTC](https://discourse.julialang.org/t/petsc-jl-mpi-wrapper/77900 "2025-06-07T03:23:08Z")

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Hello, I would love to know if someone has used PETSC wrapper in Julia for MPI? I am planning to develop a parallel code using the PETSC wrapper and would like to know how extensive the PETSC functionality is in Julia.…

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## [How complete is PETSc.jl for parallel linear solves in FEM/CFD applications?](https://discourse.julialang.org/t/how-complete-is-petsc-jl-for-parallel-linear-solves-in-fem-cfd-applications/129227)

<div class="topic-metadata">

**Author:** [@priyanshuFSI](https://discourse.julialang.org/u/priyanshuFSI)\
**Replies:** 1\
**Last updated:** [June 7, 2025, 3:17am UTC](https://discourse.julialang.org/t/how-complete-is-petsc-jl-for-parallel-linear-solves-in-fem-cfd-applications/129227 "2025-06-07T03:17:32Z")

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Hi everyone, I’m solving a finite element (FEM) problem in Julia and need to scale up the code. The main issue for me is solving large sparse linear systems in parallel. I know that in CFD and FEM communities, many peo…

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## [Killed VS OutOfMemoryError()](https://discourse.julialang.org/t/killed-vs-outofmemoryerror/129716)

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**Author:** [@raman\_kumar](https://discourse.julialang.org/u/raman_kumar)\
**Replies:** 2\
**Last updated:** [June 7, 2025, 1:55am UTC](https://discourse.julialang.org/t/killed-vs-outofmemoryerror/129716 "2025-06-07T01:55:55Z")

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Why we have two different error messages? What is the difference between Killed and OutOfMemoryError() messages? julia\> A = fill(2, 5000000000) ERROR: OutOfMemoryError() slightly lower: julia\> A = fill(2, 4000000000) K…

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## [Dropping a column from a matrix](https://discourse.julialang.org/t/dropping-a-column-from-a-matrix/33944)

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**Author:** [@dmbates](https://discourse.julialang.org/u/dmbates)\
**Replies:** 12\
**Last updated:** [June 6, 2025, 10:51pm UTC](https://discourse.julialang.org/t/dropping-a-column-from-a-matrix/33944 "2025-06-06T22:51:27Z")

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I seem to be hitting a wall deciding how to drop a column from a matrix. My background in R tells me I should use a negative index but that is not idiomatic Julia (or even valid Julia). The best I have been able to com…

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## [State of closures, Fix1/Fix2](https://discourse.julialang.org/t/state-of-closures-fix1-fix2/118997)

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**Author:** [@Deduction42](https://discourse.julialang.org/u/Deduction42)\
**Replies:** 16\
**Last updated:** [June 6, 2025, 10:31pm UTC](https://discourse.julialang.org/t/state-of-closures-fix1-fix2/118997 "2025-06-06T22:31:51Z")

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I’ve been seeing more Base.Fix1 and Base.Fix2 inside code-bases these days, even though I thought most of these performance issues were fixed with v1.0. Apparently they aren’t? In Performance Tips it looks like we still …

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## [Efficient Event Driven Entity Component System](https://discourse.julialang.org/t/efficient-event-driven-entity-component-system/129715)

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**Author:** [@Gesee](https://discourse.julialang.org/u/Gesee)\
**Replies:** 0\
**Last updated:** [June 6, 2025, 9:38pm UTC](https://discourse.julialang.org/t/efficient-event-driven-entity-component-system/129715 "2025-06-06T21:38:25Z")

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While exploring ECS design patterns and analyzing various engine architectures, I identified a recurring trade-off between flexibility, memory locality, and query overhead. I decided to explore a different approach: an E…

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## [Time range with reversed bounds](https://discourse.julialang.org/t/time-range-with-reversed-bounds/129693)

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**Author:** [@Ju\_ska](https://discourse.julialang.org/u/Ju_ska)\
**Replies:** 5\
**Last updated:** [June 6, 2025, 4:51pm UTC](https://discourse.julialang.org/t/time-range-with-reversed-bounds/129693 "2025-06-06T16:51:12Z")

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Hi, I have: using Dates lower\_bound = Dates.Time(23,59,00) upper\_bound = Dates.Time(00,01,00) I do: julia\> collect(upper\_bound:Dates.Minute(1):lower\_bound) 1439-element Vector{Time}: 00:01:00 00:02:00 00:03:00 ⋮ …

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## [How to Run Julia Online and Create an Interactive Scene/Figure Window using Makie/GLMakie/WGLMakie on Codespaces or JuliaHub](https://discourse.julialang.org/t/how-to-run-julia-online-and-create-an-interactive-scene-figure-window-using-makie-glmakie-wglmakie-on-codespaces-or-juliahub/129662)

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**Author:** [@Maddy](https://discourse.julialang.org/u/Maddy)\
**Replies:** 6\
**Last updated:** [June 5, 2025, 8:27pm UTC](https://discourse.julialang.org/t/how-to-run-julia-online-and-create-an-interactive-scene-figure-window-using-makie-glmakie-wglmakie-on-codespaces-or-juliahub/129662 "2025-06-05T20:27:50Z")

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I am trying to run my code online, verifying if people would be able to test my Simulation online without having to download Julia on their devices. How do I use GLMakie or WGLMakie to create a Scene/Figure displayed in…

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## [Error when using Enzyme to train a model with frozen layers](https://discourse.julialang.org/t/error-when-using-enzyme-to-train-a-model-with-frozen-layers/129646)

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**Author:** [@demco](https://discourse.julialang.org/u/demco)\
**Replies:** 2\
**Last updated:** [June 5, 2025, 1:51pm UTC](https://discourse.julialang.org/t/error-when-using-enzyme-to-train-a-model-with-frozen-layers/129646 "2025-06-05T13:51:50Z")

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Hi, I am using Julia to solve a 1D poisson equation using a shallow 1 layer PINN, I have successfully implemented a code based on the 2D PINN tutorial on the Lux website. Out of curiosity, I wanted to experiment with fr…

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## [Projecting u during propagation](https://discourse.julialang.org/t/projecting-u-during-propagation/129663)

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**Author:** [@diffeqslvr](https://discourse.julialang.org/u/diffeqslvr)\
**Replies:** 3\
**Last updated:** [June 5, 2025, 1:00pm UTC](https://discourse.julialang.org/t/projecting-u-during-propagation/129663 "2025-06-05T13:00:00Z")

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I am solving a set of equations of motion that I know is only approximate and will lead to unphysical results. After each propagation step, I want to project u back onto a physical subspace. I was wondering if something…

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## [Franklin.jl project status? Alternatives?](https://discourse.julialang.org/t/franklin-jl-project-status-alternatives/129618)

<div class="topic-metadata">

**Author:** [@PowerUser64](https://discourse.julialang.org/u/PowerUser64)\
**Replies:** 7\
**Last updated:** [June 5, 2025, 10:06am UTC](https://discourse.julialang.org/t/franklin-jl-project-status-alternatives/129618 "2025-06-05T10:06:19Z")

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I was looking around for a static site generator (SSG) to write a blog with, and I noticed that Franklin.jl seems to be unmaintained right now, as the last commit was over a year ago. (Source: Contributors to tlien…

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## [Which copy function should I overload?](https://discourse.julialang.org/t/which-copy-function-should-i-overload/129595)

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**Author:** [@mhauru](https://discourse.julialang.org/u/mhauru)\
**Replies:** 9\
**Last updated:** [June 5, 2025, 7:42am UTC](https://discourse.julialang.org/t/which-copy-function-should-i-overload/129595 "2025-06-05T07:42:26Z")

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I have an abstract type, call it Abe, subtypes of which may or may not be mutable. I want a function that I can call on Abes that will make a (deepish) copy of the ones that are mutable (or in some cases wrap objects tha…

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## [Surprising slowdown from using array comprehension](https://discourse.julialang.org/t/surprising-slowdown-from-using-array-comprehension/129583)

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**Author:** [@jwortmann](https://discourse.julialang.org/u/jwortmann)\
**Replies:** 8\
**Last updated:** [June 4, 2025, 10:01pm UTC](https://discourse.julialang.org/t/surprising-slowdown-from-using-array-comprehension/129583 "2025-06-04T22:01:56Z")

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Hello! I recently came across a (for me) quite difficult to debug performance issue in my code, and it still leaves me somewhat puzzled. An algorithm that I wrote seems to experience severe slowdowns when using an array …

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## [Tracking a program and storing information in a data structure](https://discourse.julialang.org/t/tracking-a-program-and-storing-information-in-a-data-structure/129651)

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**Author:** [@billyblueberry](https://discourse.julialang.org/u/billyblueberry)\
**Replies:** 0\
**Last updated:** [June 4, 2025, 6:06pm UTC](https://discourse.julialang.org/t/tracking-a-program-and-storing-information-in-a-data-structure/129651 "2025-06-04T18:06:50Z")

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I am relatively new to Julia (\<1 year) and I am developing a tool for tracking floating point addition. I have set up my work as a package, here is a reduced MWE: module TestModule # used for storing information when a…

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## [In 1.11 and 1.10: ERROR: expected package \`JuliaSyntaxHighlighting \[dc6e5ff7\]\` to be registered](https://discourse.julialang.org/t/in-1-11-and-1-10-error-expected-package-juliasyntaxhighlighting-dc6e5ff7-to-be-registered/122555)

<div class="topic-metadata">

**Author:** [@Palli](https://discourse.julialang.org/u/Palli)\
**Replies:** 1\
**Last updated:** [May 27, 2025, 11:42am UTC](https://discourse.julialang.org/t/in-1-11-and-1-10-error-expected-package-juliasyntaxhighlighting-dc6e5ff7-to-be-registered/122555 "2025-05-27T11:42:16Z")

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What is it about? I removed my ./Project.toml file just in case, then: $ julia +1.11 --project=. julia\> using JSON .. Resolving package versions... ERROR: expected package \`JuliaSyntaxHighlighting \[dc6e5ff7\]\` to be …

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## [Navigation between tests & src/](https://discourse.julialang.org/t/navigation-between-tests-src/129390)

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**Author:** [@Ken\_Williams](https://discourse.julialang.org/u/Ken_Williams)\
**Replies:** 14\
**Last updated:** [June 4, 2025, 3:50pm UTC](https://discourse.julialang.org/t/navigation-between-tests-src/129390 "2025-06-04T15:50:57Z")

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This is a pretty minor thing, but I figured I’d ask about it anyway. In VS Code, when working on code in a package, I can command-click on a function call and be taken to its definition (although if there are multiple m…

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## [Julia Script-Based Development Workflow](https://discourse.julialang.org/t/julia-script-based-development-workflow/129639)

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**Author:** [@lopenguin](https://discourse.julialang.org/u/lopenguin)\
**Replies:** 5\
**Last updated:** [June 4, 2025, 3:43pm UTC](https://discourse.julialang.org/t/julia-script-based-development-workflow/129639 "2025-06-04T15:43:47Z")

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Hi all, I’m looking for advice on a development workflow for Julia. I really like how easy it is to debug scripts (most variables can be checked in the REPL after running). On the other hand, packages with functions run…

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## [How to change the number of threads?](https://discourse.julialang.org/t/how-to-change-the-number-of-threads/6169)

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**Author:** [@jw3126](https://discourse.julialang.org/u/jw3126)\
**Replies:** 10\
**Last updated:** [June 4, 2025, 3:00pm UTC](https://discourse.julialang.org/t/how-to-change-the-number-of-threads/6169 "2025-06-04T15:00:41Z")

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How to change the number of threads? Currently it is one for me: julia\> Threads.nthreads() 1 Is there a function/command line flag to add more threads? Is this documented somewhere?

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## [What is interaction between F.() broadcasting and keyword args?](https://discourse.julialang.org/t/what-is-interaction-between-f-broadcasting-and-keyword-args/3648)

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**Author:** [@ndbecker](https://discourse.julialang.org/u/ndbecker)\
**Replies:** 13\
**Last updated:** [June 4, 2025, 12:44pm UTC](https://discourse.julialang.org/t/what-is-interaction-between-f-broadcasting-and-keyword-args/3648 "2025-06-04T12:44:49Z")

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How does F.(a, b; c=d) work with respect to broadcasting? I understand that the arguments a, b will be broadcast. What about the keyword argument?

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## [How to better initialize a dictionary containing multidimensional array?](https://discourse.julialang.org/t/how-to-better-initialize-a-dictionary-containing-multidimensional-array/129632)

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**Author:** [@Harrykjg-physics](https://discourse.julialang.org/u/Harrykjg-physics)\
**Replies:** 10\
**Last updated:** [June 4, 2025, 11:52am UTC](https://discourse.julialang.org/t/how-to-better-initialize-a-dictionary-containing-multidimensional-array/129632 "2025-06-04T11:52:38Z")

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Hi everyone, I want to create a Dict() object where the keys are NTuple{6, Int} and the corresponding values are rank-6 arrays. I found the following function to create such Dict object with 64 items are much slower than…

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## [What's the best GUI library for doing asynchronous work?](https://discourse.julialang.org/t/whats-the-best-gui-library-for-doing-asynchronous-work/128525)

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**Author:** [@AwesomeQuest](https://discourse.julialang.org/u/AwesomeQuest)\
**Replies:** 6\
**Last updated:** [June 4, 2025, 9:48am UTC](https://discourse.julialang.org/t/whats-the-best-gui-library-for-doing-asynchronous-work/128525 "2025-06-04T09:48:02Z")

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I’m making a GUI to control a robot over serial and I want to be able to use buttons and text fields to control asynchronous loops that send and receive data over serial. What GUI library makes this easiest? There seem …

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## [Equivelent HTTP.jl code for Python socket implementation](https://discourse.julialang.org/t/equivelent-http-jl-code-for-python-socket-implementation/129566)

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**Author:** [@AwesomeQuest](https://discourse.julialang.org/u/AwesomeQuest)\
**Replies:** 1\
**Last updated:** [June 3, 2025, 9:50am UTC](https://discourse.julialang.org/t/equivelent-http-jl-code-for-python-socket-implementation/129566 "2025-06-03T09:50:13Z")

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I’m trying to emulate a piece of Python code that talks to a http server in Julia but I don’t really understand the python code or how to translate it into equivalent HTTP.jl and Sockets.jl code. Here’s a very compresse…

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## [How can interfaces work with symbolic-diff?](https://discourse.julialang.org/t/how-can-interfaces-work-with-symbolic-diff/129565)

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**Author:** [@mrufsvold](https://discourse.julialang.org/u/mrufsvold)\
**Replies:** 8\
**Last updated:** [June 3, 2025, 9:01am UTC](https://discourse.julialang.org/t/how-can-interfaces-work-with-symbolic-diff/129565 "2025-06-03T09:01:18Z")

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In @MilesCranmer’s post about abstract typing, @ChrisRackauckas wrote I didn’t want to take that thread off topic, so pulling this out. I’m interested to see @ChrisRackauckas mention function interfaces as a solution w…

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## [Sum over view of BitArray](https://discourse.julialang.org/t/sum-over-view-of-bitarray/129585)

<div class="topic-metadata">

**Author:** [@jerry\_ji](https://discourse.julialang.org/u/jerry_ji)\
**Replies:** 3\
**Last updated:** [June 3, 2025, 8:39am UTC](https://discourse.julialang.org/t/sum-over-view-of-bitarray/129585 "2025-06-03T08:39:39Z")

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q=trues(10000) d=view(q,1:10000) @btime sum($q) 17.034 ns (0 allocations: 0 bytes) 10000 @btime sum($d) 2.678 μs (0 allocations: 0 bytes) 10000 how can i improve performance of sum over continuous subset of a Bit…

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## [VS Code won't run tests anymore](https://discourse.julialang.org/t/vs-code-wont-run-tests-anymore/129233)

<div class="topic-metadata">

**Author:** [@Ken\_Williams](https://discourse.julialang.org/u/Ken_Williams)\
**Replies:** 14\
**Last updated:** [June 3, 2025, 7:08am UTC](https://discourse.julialang.org/t/vs-code-wont-run-tests-anymore/129233 "2025-06-03T07:08:43Z")

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My test pane (with the chemistry beaker icon) in VS Code won’t run tests anymore, as of this week. When I click on the “run” button, for all of the tests together or just a single test, it seems to just hang forever. R…

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## [Downloads.download not working on github while OS curl does](https://discourse.julialang.org/t/downloads-download-not-working-on-github-while-os-curl-does/129272)

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**Author:** [@disberd](https://discourse.julialang.org/u/disberd)\
**Replies:** 15\
**Last updated:** [June 2, 2025, 7:55pm UTC](https://discourse.julialang.org/t/downloads-download-not-working-on-github-while-os-curl-does/129272 "2025-06-02T19:55:40Z")

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Hi All, I am facing problems downloading artifacts on a linux remote server I connect to via SSH. This is an issue that I have been facing only in the last days and I am using this server daily since months now. This i…

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## [Disable promotion from Float64 to BigFloat](https://discourse.julialang.org/t/disable-promotion-from-float64-to-bigfloat/129529)

<div class="topic-metadata">

**Author:** [@iryabink](https://discourse.julialang.org/u/iryabink)\
**Replies:** 20\
**Last updated:** [June 2, 2025, 5:28pm UTC](https://discourse.julialang.org/t/disable-promotion-from-float64-to-bigfloat/129529 "2025-06-02T17:28:26Z")

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Dear community, Recently, I’ve been trying to debug an arbitrary precision algorithms/formulae. I stumbled upon to the fact that it is by default users are allowed to have mixed precision input without any warnings, e.g…

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