# General Usage

**URL:** https://discourse.julialang.org/c/usage/6.md?page=45

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

**Page:** 46

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## [Error using TestItems in VSCode](https://discourse.julialang.org/t/error-using-testitems-in-vscode/120699)

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**Author:** [@brianguenter](https://discourse.julialang.org/u/brianguenter)\
**Replies:** 21\
**Last updated:** [August 18, 2025, 9:41pm UTC](https://discourse.julialang.org/t/error-using-testitems-in-vscode/120699 "2025-08-18T21:41:47Z")

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I get this error when I try to run tests using the TestItems framework in VSCode: An error occurred attempting to run tests: Error: Pending response rejected since connection got disposed The test runs fine from the VS…

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## [Writing a function that also works broadcasts over DataFrames](https://discourse.julialang.org/t/writing-a-function-that-also-works-broadcasts-over-dataframes/131675)

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**Author:** [@freeman](https://discourse.julialang.org/u/freeman)\
**Replies:** 16\
**Last updated:** [August 18, 2025, 9:07pm UTC](https://discourse.julialang.org/t/writing-a-function-that-also-works-broadcasts-over-dataframes/131675 "2025-08-18T21:07:04Z")

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I love broadcasting over arrays. I love that in Julia I can define func(x) where x is e.g. a namedtuple and then call it on func.(x) where x is a vector of namedtuples. However… I’m having difficulty extending this to …

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## [Segmentation fault in executable after compilation with juliac including --trim --experimental arguments](https://discourse.julialang.org/t/segmentation-fault-in-executable-after-compilation-with-juliac-including-trim-experimental-arguments/125303)

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**Author:** [@borisjo](https://discourse.julialang.org/u/borisjo)\
**Replies:** 4\
**Last updated:** [August 18, 2025, 9:10pm UTC](https://discourse.julialang.org/t/segmentation-fault-in-executable-after-compilation-with-juliac-including-trim-experimental-arguments/125303 "2025-08-18T21:10:39Z")

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I’m trying out the juliac compilation functionality and I’m getting segmentation faults in my executable. My code I try to compile: module ABCD Base.@ccallable function main()::Cint return 0 end end # Module ABCD…

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## [Building a Julia-Powered E-Ink Dashboard: A Dev Log](https://discourse.julialang.org/t/building-a-julia-powered-e-ink-dashboard-a-dev-log/130709)

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**Author:** [@TheCedarPrince](https://discourse.julialang.org/u/TheCedarPrince)\
**Replies:** 16\
**Last updated:** [August 18, 2025, 7:18pm UTC](https://discourse.julialang.org/t/building-a-julia-powered-e-ink-dashboard-a-dev-log/130709 "2025-08-18T19:18:12Z")

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Every great journey starts with a single step. :man\_mage: In the spirit of open source, adventure, and fun, I am making an on-going development log here about building a Julia-powered e-ink dashboard ran on a Raspberr…

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## [How does nested tab completion work in the REPL?](https://discourse.julialang.org/t/how-does-nested-tab-completion-work-in-the-repl/102953)

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**Author:** [@mkitti](https://discourse.julialang.org/u/mkitti)\
**Replies:** 7\
**Last updated:** [August 18, 2025, 7:15pm UTC](https://discourse.julialang.org/t/how-does-nested-tab-completion-work-in-the-repl/102953 "2025-08-18T19:15:31Z")

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How does nested tab completion work in the REPL? I notice I can get this to work with nested NamedTuple but I am struggling to get it to work with a custom type.

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## [Thread safe memoization](https://discourse.julialang.org/t/thread-safe-memoization/131673)

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**Author:** [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Replies:** 17\
**Last updated:** [August 18, 2025, 3:57pm UTC](https://discourse.julialang.org/t/thread-safe-memoization/131673 "2025-08-18T15:57:40Z")

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I have the following code, using memoization: # Copyright (c) 2025 Marcus Becker, Uwe Fechner # SPDX-License-Identifier: BSD-3-Clause """ discretizeRotor(n\_rp::Int) -\> Tuple{Matrix{Float64}, Vector{Float64}} Discr…

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## [Parallel Processing and Eigenvalue calculation](https://discourse.julialang.org/t/parallel-processing-and-eigenvalue-calculation/131659)

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**Author:** [@FranciscoZick](https://discourse.julialang.org/u/FranciscoZick)\
**Replies:** 2\
**Last updated:** [August 18, 2025, 9:41am UTC](https://discourse.julialang.org/t/parallel-processing-and-eigenvalue-calculation/131659 "2025-08-18T09:41:41Z")

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Hey everyone, I’m not necessarily new to Julia but new to parallel processing and writing fast code. I am trying to optimize this piece of code: BLAS.set\_num\_threads(16) MAX\_CONC = 4 # limit to 4 concurrent tasks @s…

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## [Strategy to get best performance with @turbo and multithreading in real applications?](https://discourse.julialang.org/t/strategy-to-get-best-performance-with-turbo-and-multithreading-in-real-applications/131666)

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**Author:** [@jsjie](https://discourse.julialang.org/u/jsjie)\
**Replies:** 3\
**Last updated:** [August 18, 2025, 5:04am UTC](https://discourse.julialang.org/t/strategy-to-get-best-performance-with-turbo-and-multithreading-in-real-applications/131666 "2025-08-18T05:04:25Z")

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A simple example is shown in the end of the post. It can be seen that for the smaller vectors, the multithreading in @turbo makes no difference. For the larger vectors, increasing nthreads will enhance the performance, b…

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## [Exception Control in Iteration over Channels, Latest Version](https://discourse.julialang.org/t/exception-control-in-iteration-over-channels-latest-version/131651)

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**Author:** [@mraic1](https://discourse.julialang.org/u/mraic1)\
**Replies:** 8\
**Last updated:** [August 17, 2025, 8:49pm UTC](https://discourse.julialang.org/t/exception-control-in-iteration-over-channels-latest-version/131651 "2025-08-17T20:49:46Z")

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Dear all, I got intrigued when I realized that exceptions can be silenced when iterating over a channel. However, the source code on GitHub indicates that exceptions should actually be rethrown. Then I realized that the…

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## [Failing to install OrdinaryDiffEq in the new Julia update](https://discourse.julialang.org/t/failing-to-install-ordinarydiffeq-in-the-new-julia-update/131511)

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**Author:** [@Marco\_Masi](https://discourse.julialang.org/u/Marco_Masi)\
**Replies:** 10\
**Last updated:** [August 17, 2025, 7:40pm UTC](https://discourse.julialang.org/t/failing-to-install-ordinarydiffeq-in-the-new-julia-update/131511 "2025-08-17T19:40:12Z")

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I installed the latest version of Julia (in Windows), and I am encountering issues with the ODE package. Neither launching nor importing it resolves the problem. I initially thought the issue might be due to an incorrect…

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## [Help to build a django-like orm in julia](https://discourse.julialang.org/t/help-to-build-a-django-like-orm-in-julia/105091)

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**Author:** [@Rafael\_Brus](https://discourse.julialang.org/u/Rafael_Brus)\
**Replies:** 7\
**Last updated:** [August 17, 2025, 12:47pm UTC](https://discourse.julialang.org/t/help-to-build-a-django-like-orm-in-julia/105091 "2025-08-17T12:47:42Z")

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I’m spending some time these last days studying the viability of building a Django-like orm in julia. I made some progress, but I haven’t had much luck with the performance. I’ve used the searchlight with the start point…

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## [Question about cluster setup on windows](https://discourse.julialang.org/t/question-about-cluster-setup-on-windows/104972)

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**Author:** [@lionisxn](https://discourse.julialang.org/u/lionisxn)\
**Replies:** 5\
**Last updated:** [August 17, 2025, 1:53am UTC](https://discourse.julialang.org/t/question-about-cluster-setup-on-windows/104972 "2025-08-17T01:53:54Z")

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I am learning how to build up a computer cluster for computation. Now I have already started up the SSH service on one server running windows 10 and keep the same julia version of the latest 1.9.3 installed in the same p…

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## [Gtk4.jl get selected values from GtkMultiSelection](https://discourse.julialang.org/t/gtk4-jl-get-selected-values-from-gtkmultiselection/131596)

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**Author:** [@jwright11](https://discourse.julialang.org/u/jwright11)\
**Replies:** 3\
**Last updated:** [August 17, 2025, 12:31am UTC](https://discourse.julialang.org/t/gtk4-jl-get-selected-values-from-gtkmultiselection/131596 "2025-08-17T00:31:15Z")

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Does anyone know how to get the user-selected values from a GtkMultiSelection in Gtk4.jl? I am trying the example code found here and shown below. I can’t seem to find any documentation on how to do it. using Gtk4 mod…

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## [Using pmap within a package](https://discourse.julialang.org/t/using-pmap-within-a-package/131627)

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**Author:** [@veddox](https://discourse.julialang.org/u/veddox)\
**Replies:** 6\
**Last updated:** [August 16, 2025, 9:26am UTC](https://discourse.julialang.org/t/using-pmap-within-a-package/131627 "2025-08-16T09:26:40Z")

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I’ve been trying to wrap my head around how to use pmap() properly within a package, but I’m still a bit confused and am starting to suspect my original plan may not work. For context: I’m working on a process-based eco…

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## [Dividing a Dataframe](https://discourse.julialang.org/t/dividing-a-dataframe/131631)

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**Author:** [@SergeantMike67](https://discourse.julialang.org/u/SergeantMike67)\
**Replies:** 6\
**Last updated:** [August 15, 2025, 9:54pm UTC](https://discourse.julialang.org/t/dividing-a-dataframe/131631 "2025-08-15T21:54:54Z")

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I have a dataframe Row │ VarietyA VarietyB Variety.p.adj │ String String Float64 ─────┼─────────────────────────…

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## [Why has simple threading using \`threadid\` become so complex in v1.12...?](https://discourse.julialang.org/t/why-has-simple-threading-using-threadid-become-so-complex-in-v1-12/129135)

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**Author:** [@Datseris](https://discourse.julialang.org/u/Datseris)\
**Replies:** 39\
**Last updated:** [August 15, 2025, 9:50pm UTC](https://discourse.julialang.org/t/why-has-simple-threading-using-threadid-become-so-complex-in-v1-12/129135 "2025-08-15T21:50:30Z")

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Hi, several of my repos got raised an issue for the upcoming v1.12 and changes to multithreading, notifying of erroneous usage of threadid. E.g., Likely erroneous use of \`Threads.nthreads\` and \`Threads.threadid\` · Issue …

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## [Handling errors in threads](https://discourse.julialang.org/t/handling-errors-in-threads/94321)

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**Author:** [@Ross\_Boylan](https://discourse.julialang.org/u/Ross_Boylan)\
**Replies:** 1\
**Last updated:** [August 15, 2025, 3:52pm UTC](https://discourse.julialang.org/t/handling-errors-in-threads/94321 "2025-08-15T15:52:27Z")

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My program keeps encountering errors in threads it has spawned; the only symptom I see is the main thread stalled trying to assign work. The tendency of threads and tasks to swallow errors silently is apparently long-st…

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## [Symbolics.jl and Latexify.jl: customize latex representations?](https://discourse.julialang.org/t/symbolics-jl-and-latexify-jl-customize-latex-representations/72180)

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**Author:** [@adomasbaliuka](https://discourse.julialang.org/u/adomasbaliuka)\
**Replies:** 4\
**Last updated:** [August 15, 2025, 3:00pm UTC](https://discourse.julialang.org/t/symbolics-jl-and-latexify-jl-customize-latex-representations/72180 "2025-08-15T15:00:52Z")

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(Julia 1.6) I deal with equations from publications and the variables there have lots of subscripts and superscripts. They cannot be represented as Julia variable names and I would prefer not to compromise. For example,…

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## [Optimizing multi-threading of tasks of varying duration](https://discourse.julialang.org/t/optimizing-multi-threading-of-tasks-of-varying-duration/131521)

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**Author:** [@oscarvdvelde](https://discourse.julialang.org/u/oscarvdvelde)\
**Replies:** 8\
**Last updated:** [August 15, 2025, 2:39pm UTC](https://discourse.julialang.org/t/optimizing-multi-threading-of-tasks-of-varying-duration/131521 "2025-08-15T14:39:54Z")

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I am processing batches of data by 10-minute time steps. Per step, my script calls an external binary (like 10 times as a sort of Monte Carlo variation) that produces data from raw files, and writes output, which is then…

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## [Julia callback not invoked by C library. Works manually (in script) but not in function](https://discourse.julialang.org/t/julia-callback-not-invoked-by-c-library-works-manually-in-script-but-not-in-function/131561)

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**Author:** [@amit1](https://discourse.julialang.org/u/amit1)\
**Replies:** 9\
**Last updated:** [August 15, 2025, 9:41am UTC](https://discourse.julialang.org/t/julia-callback-not-invoked-by-c-library-works-manually-in-script-but-not-in-function/131561 "2025-08-15T09:41:50Z")

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I’m developing a Julia wrapper for KIM-API called kim\_api.jl and encountering a puzzling issue where my Julia callback function isn’t being invoked by the C library during computation. So KIM-API is supposed to register…

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## [No more threadid indexing? \[thread-local storage\]](https://discourse.julialang.org/t/no-more-threadid-indexing-thread-local-storage/131535)

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**Author:** [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Replies:** 36\
**Last updated:** [August 15, 2025, 5:12am UTC](https://discourse.julialang.org/t/no-more-threadid-indexing-thread-local-storage/131535 "2025-08-15T05:12:13Z")

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I am implementing multi-threaded scientific software, an so far it works quite well. But now I am told that thread-local storage is no longer supported by Julia. Well, it still works, even under Julia 1.12rc1, but i am …

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## [Does Revise/CodeTracking work with PrecompileTools](https://discourse.julialang.org/t/does-revise-codetracking-work-with-precompiletools/131615)

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**Author:** [@co1emi11er](https://discourse.julialang.org/u/co1emi11er)\
**Replies:** 7\
**Last updated:** [August 15, 2025, 4:38am UTC](https://discourse.julialang.org/t/does-revise-codetracking-work-with-precompiletools/131615 "2025-08-15T04:38:35Z")

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I can’t seem to get things to precompile for my package when I try to use CodeTracking. @setup\_workload begin # Putting some things in \`@setup\_workload\` instead of \`@compile\_workload\` can reduce the size of the …

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## [Problems installing RSvg.jl on Windows](https://discourse.julialang.org/t/problems-installing-rsvg-jl-on-windows/131308)

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**Author:** [@cormullion](https://discourse.julialang.org/u/cormullion)\
**Replies:** 17\
**Last updated:** [August 14, 2025, 8:34pm UTC](https://discourse.julialang.org/t/problems-installing-rsvg-jl-on-windows/131308 "2025-08-14T20:34:15Z")

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Some people are having trouble installing Rsvg.jl on Windows (Luxor doesn't compile on julia v1.11.5 · Issue #332 · JuliaGraphics/Luxor.jl · GitHub). Can anyone with Windows (and a few spare minutes) install Rsvg.jl (or …

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## [How to divide a project into files and submodules?](https://discourse.julialang.org/t/how-to-divide-a-project-into-files-and-submodules/131593)

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**Author:** [@Snowy](https://discourse.julialang.org/u/Snowy)\
**Replies:** 5\
**Last updated:** [August 14, 2025, 5:42pm UTC](https://discourse.julialang.org/t/how-to-divide-a-project-into-files-and-submodules/131593 "2025-08-14T17:42:26Z")

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Thanks, this seems like probably a little more of an elegant solution. If working on a large project, is the best solution here to create a module with defined structs then include them in other appropriate modules?

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## [Find out which solver was used in automatic solver selection](https://discourse.julialang.org/t/find-out-which-solver-was-used-in-automatic-solver-selection/131564)

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**Author:** [@diffeqslvr](https://discourse.julialang.org/u/diffeqslvr)\
**Replies:** 5\
**Last updated:** [August 14, 2025, 10:16am UTC](https://discourse.julialang.org/t/find-out-which-solver-was-used-in-automatic-solver-selection/131564 "2025-08-14T10:16:20Z")

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In julia, I am using an automatic solver selection to solve differential equations using the DifferentialEquations package. I would like to know which solver was used in the end, but when I run sol.alg, I get CompositeA…

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## [Strange GC issue on Julia 1.12-rc1](https://discourse.julialang.org/t/strange-gc-issue-on-julia-1-12-rc1/131529)

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**Author:** [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Replies:** 9\
**Last updated:** [August 12, 2025, 9:07pm UTC](https://discourse.julialang.org/t/strange-gc-issue-on-julia-1-12-rc1/131529 "2025-08-12T21:07:17Z")

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I am happy that I can now use multi-threading on Julia 1.12rc1. I had to do some changes to my code, but now it works. But the garbage collector behaves differently. I am using two different settings. First settings: j…

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## [Package compiles only after "instantiate" but after a "resolve" that apparently doesn't change anything](https://discourse.julialang.org/t/package-compiles-only-after-instantiate-but-after-a-resolve-that-apparently-doesnt-change-anything/131582)

<div class="topic-metadata">

**Author:** [@sylvaticus](https://discourse.julialang.org/u/sylvaticus)\
**Replies:** 7\
**Last updated:** [August 14, 2025, 9:44am UTC](https://discourse.julialang.org/t/package-compiles-only-after-instantiate-but-after-a-resolve-that-apparently-doesnt-change-anything/131582 "2025-08-14T09:44:17Z")

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Ok, this happens often when I add a new dependency to a package I am developing. My issue is that the sequence I need to go is to make an istantiate, resolve, istantiate, but the message on resolve looks like this resol…

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## [How does one turn off Autodiff +Jacobian in DifferentialEquations.jl solvers?](https://discourse.julialang.org/t/how-does-one-turn-off-autodiff-jacobian-in-differentialequations-jl-solvers/131588)

<div class="topic-metadata">

**Author:** [@erny123](https://discourse.julialang.org/u/erny123)\
**Replies:** 4\
**Last updated:** [August 14, 2025, 4:39am UTC](https://discourse.julialang.org/t/how-does-one-turn-off-autodiff-jacobian-in-differentialequations-jl-solvers/131588 "2025-08-14T04:39:20Z")

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EDIT I’m trying to solve a simple mixed point BVP such as: \\partial\_z \\mathbf{a} = C\_1 \\mathbf{a} + g \\mathbf{a} \\mathbf{b} \\mathbf{b}^{\*} \\partial\_z \\mathbf{b} = C\_2 \\mathbf{b} + g \\mathbf{b} \\mathbf{a} \\ma…

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## [Struct copy with change in the value of fields](https://discourse.julialang.org/t/struct-copy-with-change-in-the-value-of-fields/19592)

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**Author:** [@rveltz](https://discourse.julialang.org/u/rveltz)\
**Replies:** 8\
**Last updated:** [August 14, 2025, 12:33am UTC](https://discourse.julialang.org/t/struct-copy-with-change-in-the-value-of-fields/19592 "2025-08-14T00:33:29Z")

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Hi, I have an anoying situation where I want to copy a variable of composed type by changing a value of the field which may in turn change the type. Here is an example # in my application, the following struct contain…

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## [How can I start a Julia worker on my laptop from a remote server?](https://discourse.julialang.org/t/how-can-i-start-a-julia-worker-on-my-laptop-from-a-remote-server/131406)

<div class="topic-metadata">

**Author:** [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Replies:** 12\
**Last updated:** [August 13, 2025, 12:30pm UTC](https://discourse.julialang.org/t/how-can-i-start-a-julia-worker-on-my-laptop-from-a-remote-server/131406 "2025-08-13T12:30:45Z")

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I can use ssh to connect to a remote server. Now I would like to display plots on my laptop (from the server) by launching a worker on my laptop using the addprocs function. I have this code, which works fine as long as…

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