# General Usage

**URL:** https://discourse.julialang.org/c/usage/6.md?page=516

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

**Page:** 517

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## [Exist a type tree of all types?](https://discourse.julialang.org/t/exist-a-type-tree-of-all-types/71913)

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**Author:** [@MeteorBizone](https://discourse.julialang.org/u/MeteorBizone)\
**Replies:** 5\
**Last updated:** [November 23, 2021, 11:26am UTC](https://discourse.julialang.org/t/exist-a-type-tree-of-all-types/71913 "2021-11-23T11:26:40Z")

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Hello, I’am new. Exist a picture with a type tree of all Julia types?

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## [Conda.search](https://discourse.julialang.org/t/conda-search/71936)

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**Author:** [@ellocco](https://discourse.julialang.org/u/ellocco)\
**Replies:** 0\
**Last updated:** [November 23, 2021, 10:53am UTC](https://discourse.julialang.org/t/conda-search/71936 "2021-11-23T10:53:41Z")

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Sorry I do not know how to remove this post, it is a known issue in “Conda.jl” /Conda.jl/issues/118 I am struggling with the Conda method “search”, is it a bug or do I missunderstand something, why is following throwin…

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## [How to build functions that work efficiently with arguments of different types?](https://discourse.julialang.org/t/how-to-build-functions-that-work-efficiently-with-arguments-of-different-types/71504)

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**Author:** [@MichaelGao](https://discourse.julialang.org/u/MichaelGao)\
**Replies:** 15\
**Last updated:** [November 23, 2021, 9:57am UTC](https://discourse.julialang.org/t/how-to-build-functions-that-work-efficiently-with-arguments-of-different-types/71504 "2021-11-23T09:57:58Z")

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For implementing sensitivity analysis, I need to build some functions, for example like the one below. function just\_an\_example(a, b, C) a::Float64 b::Float64 C::Vector{Float64} return a + b\*C end (…

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## [You appear to have run julia under a different \`mpiexec\` than the one used by MPI.jl](https://discourse.julialang.org/t/you-appear-to-have-run-julia-under-a-different-mpiexec-than-the-one-used-by-mpi-jl/51836)

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**Author:** [@Daniel\_Blatter](https://discourse.julialang.org/u/Daniel_Blatter)\
**Replies:** 4\
**Last updated:** [November 22, 2021, 9:53pm UTC](https://discourse.julialang.org/t/you-appear-to-have-run-julia-under-a-different-mpiexec-than-the-one-used-by-mpi-jl/51836 "2021-11-22T21:53:52Z")

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I’m running MacOS 10.15.6 and I use OpenMPI to run Julia programs. It worked fine with Julia 1.1. Then I uninstalled Julia 1.1, installed Julia 1.5.3, added the MPI.jl package, and now I get the following error whenever …

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## [Serial synchronization issue and request for some general advice](https://discourse.julialang.org/t/serial-synchronization-issue-and-request-for-some-general-advice/71921)

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**Author:** [@zchris9](https://discourse.julialang.org/u/zchris9)\
**Replies:** 1\
**Last updated:** [November 23, 2021, 7:44am UTC](https://discourse.julialang.org/t/serial-synchronization-issue-and-request-for-some-general-advice/71921 "2021-11-23T07:44:51Z")

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Dear Julia Community! I am currently working on a university project where data is streamed to a Raspberry Pi 4 and needs to be processed in a soft real-time environment. The projects goal is to provide infrastructure f…

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## [Unitful - derived unit simplification?](https://discourse.julialang.org/t/unitful-derived-unit-simplification/71186)

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**Author:** [@mde](https://discourse.julialang.org/u/mde)\
**Replies:** 2\
**Last updated:** [November 23, 2021, 7:32am UTC](https://discourse.julialang.org/t/unitful-derived-unit-simplification/71186 "2021-11-23T07:32:38Z")

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I am fairly new to Unitful and am running into an issue when I multiply a derived unit by one of its component units and want the resulting unit to simplify into the other component unit. Example: \> 1u"M" \* 1u"L" 1 L M…

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## [Find position on list (fast)](https://discourse.julialang.org/t/find-position-on-list-fast/71911)

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**Author:** [@programista](https://discourse.julialang.org/u/programista)\
**Replies:** 13\
**Last updated:** [November 22, 2021, 11:24pm UTC](https://discourse.julialang.org/t/find-position-on-list-fast/71911 "2021-11-22T23:24:11Z")

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Me vectors are very long and I am looking for efficient way to : If x=\[“a”;“b”;“c”;“d”;“e”\] and y=\[“b”; “a”; “a”; “c”\] How to find , but very fast, position any y on x expected result: 2 1 1 3 Thanks Pauls

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## [Constructing expressions with local macro variables and Symbols](https://discourse.julialang.org/t/constructing-expressions-with-local-macro-variables-and-symbols/71906)

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**Author:** [@filchristou](https://discourse.julialang.org/u/filchristou)\
**Replies:** 11\
**Last updated:** [November 22, 2021, 9:04pm UTC](https://discourse.julialang.org/t/constructing-expressions-with-local-macro-variables-and-symbols/71906 "2021-11-22T21:04:25Z")

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I want to construct an expression inside a macro, given a particular input parameter. The behavior should be like that: julia\> @macroexpand @mymacro mysym\[15\] :(\[\[:mysym\], 15\]) So I tried to write something like that: …

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## [Error in markdown with Weave.jl](https://discourse.julialang.org/t/error-in-markdown-with-weave-jl/71909)

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**Author:** [@Adam\_D](https://discourse.julialang.org/u/Adam_D)\
**Replies:** 1\
**Last updated:** [November 22, 2021, 7:56pm UTC](https://discourse.julialang.org/t/error-in-markdown-with-weave-jl/71909 "2021-11-22T19:56:37Z")

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Hi all, I just learnt that julia has markdown enabled by Weave.jl. I wanted to give it a try but I am having trouble creating a pdf document. Unfortunately, unlike Rmarkdown, there does not seem to be many resources ava…

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## [Iszero and zero: wrong usage (?) and bad error message](https://discourse.julialang.org/t/iszero-and-zero-wrong-usage-and-bad-error-message/71907)

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**Author:** [@lmiq](https://discourse.julialang.org/u/lmiq)\
**Replies:** 2\
**Last updated:** [November 22, 2021, 7:30pm UTC](https://discourse.julialang.org/t/iszero-and-zero-wrong-usage-and-bad-error-message/71907 "2021-11-22T19:30:29Z")

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I am trying to use iszero for a custom struct. I defined zero for it, which appeared to be the necessary method. But iszero does not work, and the error message is not clear, because it complains that the zero function …

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## [Makie hover tooltips in static offline html export](https://discourse.julialang.org/t/makie-hover-tooltips-in-static-offline-html-export/71810)

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**Author:** [@cyrieln](https://discourse.julialang.org/u/cyrieln)\
**Replies:** 3\
**Last updated:** [November 22, 2021, 6:43pm UTC](https://discourse.julialang.org/t/makie-hover-tooltips-in-static-offline-html-export/71810 "2021-11-22T18:43:11Z")

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Is it possible to have hover-labels in static exported HTML’s? I would like to have the behavior of DataInspector(fig) in an offline html file. This feature does not seem to translate over to html.

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## [Changing and accessing data in different threads](https://discourse.julialang.org/t/changing-and-accessing-data-in-different-threads/71899)

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**Author:** [@Impressium](https://discourse.julialang.org/u/Impressium)\
**Replies:** 3\
**Last updated:** [November 22, 2021, 4:44pm UTC](https://discourse.julialang.org/t/changing-and-accessing-data-in-different-threads/71899 "2021-11-22T16:44:07Z")

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Hi all :slight\_smile: In the docs is written that the following is not safe. https://docs.julialang.org/en/v1/manual/multi-threading/#Data-race-freedom Thread 1: global b = false global a = rand() global b = true Thr…

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## [Editable table using Stipple UI](https://discourse.julialang.org/t/editable-table-using-stipple-ui/71854)

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**Author:** [@wuxinyu](https://discourse.julialang.org/u/wuxinyu)\
**Replies:** 9\
**Last updated:** [November 22, 2021, 10:32am UTC](https://discourse.julialang.org/t/editable-table-using-stipple-ui/71854 "2021-11-22T10:32:49Z")

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I want to build a web app to interact with backend data processing. How can I write a editable table with stipple? I can’t find helpful documents and become struggling. Any help or suggestions would be much appreciated!

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## [Not understanding linear growing allocations](https://discourse.julialang.org/t/not-understanding-linear-growing-allocations/71734)

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**Author:** [@peremato](https://discourse.julialang.org/u/peremato)\
**Replies:** 27\
**Last updated:** [November 22, 2021, 4:35am UTC](https://discourse.julialang.org/t/not-understanding-linear-growing-allocations/71734 "2021-11-22T04:35:07Z")

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I’m trying to understand why returning a tuple of static vectors have the effect of constantly growing allocations. I have the following code to demonstrate using BenchmarkTools using StaticArrays Vector2 = SVector{2}{…

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## [\`mul\` dispatch to BLAS incomplete?](https://discourse.julialang.org/t/mul-dispatch-to-blas-incomplete/71831)

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**Author:** [@goerch](https://discourse.julialang.org/u/goerch)\
**Replies:** 18\
**Last updated:** [November 22, 2021, 1:34am UTC](https://discourse.julialang.org/t/mul-dispatch-to-blas-incomplete/71831 "2021-11-22T01:34:06Z")

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When translating the benchmark from Outperformed by Matlab using LinearAlgebra using MKL using BenchmarkTools function \_kron!(C::T1,A::T2,B::T3) where {T1 \<: AbstractVector,T2 \<: AbstractVector,T3 \<: AbstractVector} …

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## [Toggle Threads.@threads with a variable](https://discourse.julialang.org/t/toggle-threads-threads-with-a-variable/71818)

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**Author:** [@JackStrauss](https://discourse.julialang.org/u/JackStrauss)\
**Replies:** 8\
**Last updated:** [November 21, 2021, 10:25pm UTC](https://discourse.julialang.org/t/toggle-threads-threads-with-a-variable/71818 "2021-11-21T22:25:48Z")

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Hello I am sure the elegant answer is in the documentation, but I could not find it. I use threads but sometimes want to execute same loop without threads. Is there a way to tell Julia not to use Threads.@threads if s…

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## [VSCode: keyboard shortcuts broken?](https://discourse.julialang.org/t/vscode-keyboard-shortcuts-broken/71859)

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**Author:** [@roh\_codeur](https://discourse.julialang.org/u/roh_codeur)\
**Replies:** 2\
**Last updated:** [November 21, 2021, 8:33pm UTC](https://discourse.julialang.org/t/vscode-keyboard-shortcuts-broken/71859 "2021-11-21T20:33:00Z")

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Hi I must congratulate the VSCode team on a wonderful plugin. I have a project with multiple modules. To make it faster to develop, I follow the below pattern to debug: Create a script which calls multiple modules. I…

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## [Interpolate @show macro](https://discourse.julialang.org/t/interpolate-show-macro/71858)

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**Author:** [@filchristou](https://discourse.julialang.org/u/filchristou)\
**Replies:** 5\
**Last updated:** [November 21, 2021, 4:46pm UTC](https://discourse.julialang.org/t/interpolate-show-macro/71858 "2021-11-21T16:46:31Z")

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I want to interpolate the @show macro function. For example. I define a function f(x) = x + 1 I want to see the behavior for different inputs: julia\> \[@show f(x) for x = 1:3\]; f(x) = 2 f(x) = 3 f(x) = 4 But what I …

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## [Where does the default seed come from?](https://discourse.julialang.org/t/where-does-the-default-seed-come-from/71852)

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**Author:** [@jzr](https://discourse.julialang.org/u/jzr)\
**Replies:** 1\
**Last updated:** [November 21, 2021, 4:41am UTC](https://discourse.julialang.org/t/where-does-the-default-seed-come-from/71852 "2021-11-21T04:41:51Z")

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julia\> Random.default\_rng().seed 4-element Vector{UInt32}: 0x21fc2c5d 0x2ccb7f07 0xa6a6c199 0x7786f2df Where do these numbers come from?

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## [Unused variable in Optim?](https://discourse.julialang.org/t/unused-variable-in-optim/71840)

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**Author:** [@Joris\_Pinkse](https://discourse.julialang.org/u/Joris_Pinkse)\
**Replies:** 0\
**Last updated:** [November 20, 2021, 7:46pm UTC](https://discourse.julialang.org/t/unused-variable-in-optim/71840 "2021-11-20T19:46:51Z")

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On line 372 of newton\_trust\_region.jl of the Optim package, it defines a variable delta, which then is never used. Should that perhaps be state.delta instead? (already posted an issue on github, but hopeful that someon…

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## [Calling embedding api from within a ccall originating from Julia](https://discourse.julialang.org/t/calling-embedding-api-from-within-a-ccall-originating-from-julia/71834)

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**Author:** [@jordanmb](https://discourse.julialang.org/u/jordanmb)\
**Replies:** 0\
**Last updated:** [November 20, 2021, 4:00pm UTC](https://discourse.julialang.org/t/calling-embedding-api-from-within-a-ccall-originating-from-julia/71834 "2021-11-20T16:00:28Z")

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I’m attempting to integrate Julia into an existing Rust system. The julia embedding api works great when I have a rust executable calling into it, but if I try to call the same code from within a julia notebook it will s…

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## [Fast evaluation of multivariate integrals in Julia for integrands depending on many parameters](https://discourse.julialang.org/t/fast-evaluation-of-multivariate-integrals-in-julia-for-integrands-depending-on-many-parameters/71815)

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**Author:** [@vicdolean](https://discourse.julialang.org/u/vicdolean)\
**Replies:** 4\
**Last updated:** [November 20, 2021, 3:02pm UTC](https://discourse.julialang.org/t/fast-evaluation-of-multivariate-integrals-in-julia-for-integrands-depending-on-many-parameters/71815 "2021-11-20T15:02:35Z")

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Hi, I need to evaluate an oscillatory integral of the form \\int\_D f(x) exp(\\omega g(x)) dx on a two dimensional domain D that could be R^2, given than f(x) is a exponentially decreasing function equal to an exponentia…

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## [Plotting a phase portrait of a differential equation](https://discourse.julialang.org/t/plotting-a-phase-portrait-of-a-differential-equation/29208)

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**Author:** [@00krishna](https://discourse.julialang.org/u/00krishna)\
**Replies:** 11\
**Last updated:** [November 20, 2021, 12:18pm UTC](https://discourse.julialang.org/t/plotting-a-phase-portrait-of-a-differential-equation/29208 "2021-11-20T12:18:41Z")

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Hey Folks. I was just wondering if there was an existing package or tool for plotting the phase portrait of a system of differential equations, or a phase portrait plus direction field? I am thinking of a plot like this…

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## [Trouble installing Julia 1.6.4 to latest version of Vscode](https://discourse.julialang.org/t/trouble-installing-julia-1-6-4-to-latest-version-of-vscode/71811)

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**Author:** [@Peter-Jolly](https://discourse.julialang.org/u/Peter-Jolly)\
**Replies:** 2\
**Last updated:** [November 20, 2021, 8:31am UTC](https://discourse.julialang.org/t/trouble-installing-julia-1-6-4-to-latest-version-of-vscode/71811 "2021-11-20T08:31:54Z")

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I installed Julia 1.6.4 today (after uninstalling 1.6.3) on my Windows 11 machine. I now find I get the following error when trying to run Julia from vscode (I have set the environment path to point to Julia 1.6.4 binary…

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## [How to change the tolerance of the QRPivoted method](https://discourse.julialang.org/t/how-to-change-the-tolerance-of-the-qrpivoted-method/71753)

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**Author:** [@valperez](https://discourse.julialang.org/u/valperez)\
**Replies:** 5\
**Last updated:** [November 19, 2021, 6:08pm UTC](https://discourse.julialang.org/t/how-to-change-the-tolerance-of-the-qrpivoted-method/71753 "2021-11-19T18:08:19Z")

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Hi there :slight\_smile: I’m using the LinearAlgebra package in Julia to use the QRPivoted method. The documentation is not very clear about the use of the tolerance. I want to use que qr pivoted function on a matrix A b…

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## [Different behavior for same \`@code\_llvm\` for voxel traversal](https://discourse.julialang.org/t/different-behavior-for-same-code-llvm-for-voxel-traversal/71695)

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**Author:** [@goretkin](https://discourse.julialang.org/u/goretkin)\
**Replies:** 14\
**Last updated:** [November 20, 2021, 12:33am UTC](https://discourse.julialang.org/t/different-behavior-for-same-code-llvm-for-voxel-traversal/71695 "2021-11-20T00:33:51Z")

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I have a function that takes in a line segment. I wanted to benchmark the performance and see if there is a difference whether the line segment is specified with endpoints given in integers or floats. The function has an…

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## ["@generated" for structs?](https://discourse.julialang.org/t/generated-for-structs/71803)

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**Author:** [@wmanning-cra](https://discourse.julialang.org/u/wmanning-cra)\
**Replies:** 1\
**Last updated:** [November 20, 2021, 12:21am UTC](https://discourse.julialang.org/t/generated-for-structs/71803 "2021-11-20T00:21:05Z")

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I was playing with code that generates a struct + accompanying code, based on a set of information that can be represented with groups of symbols. It occurred to me that I could simplify the syntax around this stuff if I…

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## [DifferentialEquations.jl EnsembleThreads: crash w/increase in problem size](https://discourse.julialang.org/t/differentialequations-jl-ensemblethreads-crash-w-increase-in-problem-size/71799)

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**Author:** [@evolbio](https://discourse.julialang.org/u/evolbio)\
**Replies:** 3\
**Last updated:** [November 19, 2021, 11:15pm UTC](https://discourse.julialang.org/t/differentialequations-jl-ensemblethreads-crash-w-increase-in-problem-size/71799 "2021-11-19T23:15:23Z")

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DifferentialEquations.jl has facilities for parallel processing of the solver w/different parameters, see docs. In further testing of prior code, I added the option to run parallel threads using EmsembleThreads(), as doc…

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## [Parallelization on the CPU isn't effective](https://discourse.julialang.org/t/parallelization-on-the-cpu-isnt-effective/71795)

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**Author:** [@leopdsf](https://discourse.julialang.org/u/leopdsf)\
**Replies:** 19\
**Last updated:** [November 19, 2021, 10:29pm UTC](https://discourse.julialang.org/t/parallelization-on-the-cpu-isnt-effective/71795 "2021-11-19T22:29:52Z")

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Hello, everyone. I’m following the tutorial introduction to GPU programming in Julia (Introduction · CUDA.jl), and the first example in the tutorial discuss parallelization on CPU. Didn’t find a specific section for CPU,…

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## [How to make a Clipping of an image in Julia](https://discourse.julialang.org/t/how-to-make-a-clipping-of-an-image-in-julia/21756)

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**Author:** [@GERSON\_EZEQUIEL\_HERN](https://discourse.julialang.org/u/GERSON_EZEQUIEL_HERN)\
**Replies:** 1\
**Last updated:** [November 19, 2021, 8:01pm UTC](https://discourse.julialang.org/t/how-to-make-a-clipping-of-an-image-in-julia/21756 "2021-11-19T20:01:08Z")

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how to make a Clipping of an image in Julia When you have a grayscale image, it is quantized to one byte. (I would like to do it with a color image such as the mandrill) That means that only 255 bts can be quantified …

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