# Latest

**URL:** https://discourse.julialang.org/latest.md?page=246

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

**Page:** 247

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## [My insane garbage collector idea. Why wouldn't it work?](https://discourse.julialang.org/t/my-insane-garbage-collector-idea-why-wouldnt-it-work/124273)

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**Author:** [@Tarny\_GG\_Channie](https://discourse.julialang.org/u/Tarny_GG_Channie)\
**Replies:** 6\
**Last updated:** [December 30, 2024, 12:41pm UTC](https://discourse.julialang.org/t/my-insane-garbage-collector-idea-why-wouldnt-it-work/124273 "2024-12-30T12:41:36Z")

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This probably wouldn’t work but I can’t figure out why… Garbage collectors can either stop the world, which has the most throughput, but ruins real-time performance, or it could be concurrent, and there are many version…

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## [Forecast Time series using Neural ODE for supervised learning](https://discourse.julialang.org/t/forecast-time-series-using-neural-ode-for-supervised-learning/124268)

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**Author:** [@roilsed0903](https://discourse.julialang.org/u/roilsed0903)\
**Replies:** 0\
**Last updated:** [December 30, 2024, 5:59am UTC](https://discourse.julialang.org/t/forecast-time-series-using-neural-ode-for-supervised-learning/124268 "2024-12-30T05:59:43Z")

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I’m aiming for time series prediction. I’ve seen a good prediction of time series through the post forcast weather NODE(“Forecasting the weather with neural ODEs” taked Sebastian Callh personal blog and “Forcasting time …

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## [Error in multiple dispatch](https://discourse.julialang.org/t/error-in-multiple-dispatch/124239)

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**Author:** [@langestefan](https://discourse.julialang.org/u/langestefan)\
**Replies:** 10\
**Last updated:** [December 30, 2024, 5:28am UTC](https://discourse.julialang.org/t/error-in-multiple-dispatch/124239 "2024-12-30T05:28:25Z")

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Hi, I am trying to learn multiple dispatch and I can’t figure out why the following code is not working. module GeoLocation using TimeZones using DynamicQuantities using Unitful: Unitful using DocStringExtensions expo…

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## [Feasibility Inquiry: Building a Chemical Process Simulation and Optimization Package with JuMP](https://discourse.julialang.org/t/feasibility-inquiry-building-a-chemical-process-simulation-and-optimization-package-with-jump/109236)

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**Author:** [@JackaChou](https://discourse.julialang.org/u/JackaChou)\
**Replies:** 44\
**Last updated:** [December 30, 2024, 3:56am UTC](https://discourse.julialang.org/t/feasibility-inquiry-building-a-chemical-process-simulation-and-optimization-package-with-jump/109236 "2024-12-30T03:56:21Z")

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I am a user of JuMP and am aware that the Institute for the Design of Advanced Energy Systems (IDAES) is a recently developed tool built on Python that utilizes the Pyomo optimization modeling language (https://doi.org/…

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## [How I made a new, very hard logic puzzle using Julia](https://discourse.julialang.org/t/how-i-made-a-new-very-hard-logic-puzzle-using-julia/124262)

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**Author:** [@Tarny\_GG\_Channie](https://discourse.julialang.org/u/Tarny_GG_Channie)\
**Replies:** 0\
**Last updated:** [December 29, 2024, 11:56pm UTC](https://discourse.julialang.org/t/how-i-made-a-new-very-hard-logic-puzzle-using-julia/124262 "2024-12-29T23:56:02Z")

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Here’s how I used Julia to make possibly one of the most difficult logic puzzles ever made. This one is truly diabolical. The question is that there are four gods, true, lie, rand, and rock. You can ask three questions…

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## [Can't refer to columns with spaces in names in @mutate](https://discourse.julialang.org/t/cant-refer-to-columns-with-spaces-in-names-in-mutate/123733)

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**Author:** [@Geoff\_Russell](https://discourse.julialang.org/u/Geoff_Russell)\
**Replies:** 4\
**Last updated:** [December 29, 2024, 11:25pm UTC](https://discourse.julialang.org/t/cant-refer-to-columns-with-spaces-in-names-in-mutate/123733 "2024-12-29T23:25:53Z")

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I want to do a simple mutate(a=b+c), but b and c have spaces in the names. Have tried various things without success. using DataFrames using TidierData df=DataFrame(“The Name”=\>\[4,5,6\],“Second Name”=\>\[7,8,9\]) @chain …

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## [Linestyles look the same in legend](https://discourse.julialang.org/t/linestyles-look-the-same-in-legend/124170)

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**Author:** [@bast](https://discourse.julialang.org/u/bast)\
**Replies:** 5\
**Last updated:** [December 29, 2024, 11:16pm UTC](https://discourse.julialang.org/t/linestyles-look-the-same-in-legend/124170 "2024-12-29T23:16:13Z")

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After increasing the linewidth the linestyles in the legend are indistinguishable: using Plots testplt = plot(0:0.1:1, rand(11), label="dashdot", ls=:dashdot, color=:black, lw=4) plot!(0:0.1:1, rand(11), label="dash", …

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## [Clp: 0 dependencies successfully precompiled in 4 seconds. 107 already precompiled](https://discourse.julialang.org/t/clp-0-dependencies-successfully-precompiled-in-4-seconds-107-already-precompiled/124148)

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**Author:** [@anonymous\_user](https://discourse.julialang.org/u/anonymous_user)\
**Replies:** 8\
**Last updated:** [December 29, 2024, 11:09pm UTC](https://discourse.julialang.org/t/clp-0-dependencies-successfully-precompiled-in-4-seconds-107-already-precompiled/124148 "2024-12-29T23:09:39Z")

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Help I cannot fix this on my Macbook julia\> Pkg.add(“Clp”) Resolving package versions… No Changes to ~/.julia/environments/v1.11/Project.toml No Changes to ~/.julia/environments/v1.11/Manifest.toml Precompiling proj…

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## [Optimization of the use of observables and globals in Makie (from script to @main function)](https://discourse.julialang.org/t/optimization-of-the-use-of-observables-and-globals-in-makie-from-script-to-main-function/124258)

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**Author:** [@oscarvdvelde](https://discourse.julialang.org/u/oscarvdvelde)\
**Replies:** 3\
**Last updated:** [December 29, 2024, 8:54pm UTC](https://discourse.julialang.org/t/optimization-of-the-use-of-observables-and-globals-in-makie-from-script-to-main-function/124258 "2024-12-29T20:54:33Z")

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I am trying to make my Makie GUI run faster and allocate less. I have just upgraded to Julia 1.11.2 and thought it was a good opportunity to use function (@main) in other words, wrap all my global scope code into a funct…

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## [Recursion base vs hand-made recursion](https://discourse.julialang.org/t/recursion-base-vs-hand-made-recursion/124235)

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**Author:** [@rocco\_sprmnt21](https://discourse.julialang.org/u/rocco_sprmnt21)\
**Replies:** 13\
**Last updated:** [December 29, 2024, 6:07pm UTC](https://discourse.julialang.org/t/recursion-base-vs-hand-made-recursion/124235 "2024-12-29T18:07:17Z")

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Trying to solve the problem d17 of this year’s AOC, I found that, among the proposed solutions, the most efficient seems to be the one that uses recursion. for example, compared to an iterative one that works on the sam…

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## [Is it okay that, in Julia, code that never executes can change the result of programs?](https://discourse.julialang.org/t/is-it-okay-that-in-julia-code-that-never-executes-can-change-the-result-of-programs/124195)

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**Author:** [@sadish-d](https://discourse.julialang.org/u/sadish-d)\
**Replies:** 27\
**Last updated:** [December 29, 2024, 12:18pm UTC](https://discourse.julialang.org/t/is-it-okay-that-in-julia-code-that-never-executes-can-change-the-result-of-programs/124195 "2024-12-29T12:18:39Z")

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Consider the following code. The x expression right after the inner let block throws an error because x is not defined in that scope. This is expected given the scoping rules inside let end block. let let x …

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## [Recommended workflow for map combining topography and street network](https://discourse.julialang.org/t/recommended-workflow-for-map-combining-topography-and-street-network/124208)

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**Author:** [@fa-bien](https://discourse.julialang.org/u/fa-bien)\
**Replies:** 8\
**Last updated:** [December 29, 2024, 11:41am UTC](https://discourse.julialang.org/t/recommended-workflow-for-map-combining-topography-and-street-network/124208 "2024-12-29T11:41:51Z")

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I want to plot what I imagine (perhaps naively) to be a simple map, combining a topographic layer and the street network, for a small geographic area (one city district). I believe I cannot use an already-existing layer …

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## [Type assertion for parametric constructors behaves strangely](https://discourse.julialang.org/t/type-assertion-for-parametric-constructors-behaves-strangely/124184)

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**Author:** [@Wu-Chenyang](https://discourse.julialang.org/u/Wu-Chenyang)\
**Replies:** 4\
**Last updated:** [December 29, 2024, 11:15am UTC](https://discourse.julialang.org/t/type-assertion-for-parametric-constructors-behaves-strangely/124184 "2024-12-29T11:15:56Z")

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struct A{T\<:Real, N} a::T A{N}(a::T) where {T,N} = new{T,N}(a) end For this simple parametric type, A{2}(1.0) fails with a TypeError, ERROR: TypeError: in A, in T, expected T\<:Real, got a value of type In…

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## [I need help with routing in the Genie app](https://discourse.julialang.org/t/i-need-help-with-routing-in-the-genie-app/124223)

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**Author:** [@gromblr1](https://discourse.julialang.org/u/gromblr1)\
**Replies:** 4\
**Last updated:** [December 29, 2024, 4:52am UTC](https://discourse.julialang.org/t/i-need-help-with-routing-in-the-genie-app/124223 "2024-12-29T04:52:24Z")

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Hola Julians :julia-smirk: i need some help por favor i am able to get the Genie app running and it opens successfully at localhost:8000 but i am getting this error every time I refresh… .how do i point the server to …

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## [Julia runs slower after many loop iterations (solve ODE problem)](https://discourse.julialang.org/t/julia-runs-slower-after-many-loop-iterations-solve-ode-problem/124238)

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**Author:** [@chooron](https://discourse.julialang.org/u/chooron)\
**Replies:** 3\
**Last updated:** [December 29, 2024, 4:00am UTC](https://discourse.julialang.org/t/julia-runs-slower-after-many-loop-iterations-solve-ode-problem/124238 "2024-12-29T04:00:38Z")

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Hello, I need to perform optimization of many groups of ODE problems. The optimization time required for the first few groups is about 20 minutes, but after completing multiple optimizations, the time required gradually …

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## [PATHSolver.jl not working on ARM Linux](https://discourse.julialang.org/t/pathsolver-jl-not-working-on-arm-linux/124203)

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**Author:** [@nealhughes](https://discourse.julialang.org/u/nealhughes)\
**Replies:** 13\
**Last updated:** [December 29, 2024, 2:35am UTC](https://discourse.julialang.org/t/pathsolver-jl-not-working-on-arm-linux/124203 "2024-12-29T02:35:53Z")

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I have a JuMP MCP model using PATHSolver.jl which works fine on Windows x86. I am trying to get it working on an ARM laptop in WSL (Ubuntu). All packages have installed fine out of the box except PATHSolver.jl, which gi…

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## [Is there a function in Base that determines the most specific type?](https://discourse.julialang.org/t/is-there-a-function-in-base-that-determines-the-most-specific-type/124215)

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**Author:** [@tqml](https://discourse.julialang.org/u/tqml)\
**Replies:** 1\
**Last updated:** [December 27, 2024, 9:38pm UTC](https://discourse.julialang.org/t/is-there-a-function-in-base-that-determines-the-most-specific-type/124215 "2024-12-27T21:38:31Z")

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I’m currently wondering if there is a function anywhere in Base or the standard library that figures out the most specific type element for a given type (e.g. like multiple dispatch does). I would like to have a functio…

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## [No method matching Float64(::ForwardDiff.Dual{Nothing, Float64, 1})](https://discourse.julialang.org/t/no-method-matching-float64-forwarddiff-dual-nothing-float64-1/124228)

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**Author:** [@CatY](https://discourse.julialang.org/u/CatY)\
**Replies:** 9\
**Last updated:** [December 29, 2024, 1:42am UTC](https://discourse.julialang.org/t/no-method-matching-float64-forwarddiff-dual-nothing-float64-1/124228 "2024-12-29T01:42:04Z")

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Hi, I’m a new user for Julia, and I’m trying to use neural networks to simulate test data with differential equations, while I’m getting an error that no method matching Float64. I checked the DifferentialEquations.jl do…

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## [Kahan summation in \`sum\`?](https://discourse.julialang.org/t/kahan-summation-in-sum/102723)

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**Author:** [@CameronBieganek](https://discourse.julialang.org/u/CameronBieganek)\
**Replies:** 13\
**Last updated:** [December 29, 2024, 1:04am UTC](https://discourse.julialang.org/t/kahan-summation-in-sum/102723 "2024-12-29T01:04:03Z")

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I was under the impression that sum(itr) uses Kahan summation, but after inspecting the Julia repo it appears that it calls mapreduce(identity, add\_sum, itr). And add\_sum is basically just + with some promotions for smal…

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## [Displaying plots alongside each other in Pluto](https://discourse.julialang.org/t/displaying-plots-alongside-each-other-in-pluto/124116)

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**Author:** [@s-baumann](https://discourse.julialang.org/u/s-baumann)\
**Replies:** 4\
**Last updated:** [December 28, 2024, 11:57am UTC](https://discourse.julialang.org/t/displaying-plots-alongside-each-other-in-pluto/124116 "2024-12-28T11:57:14Z")

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I have made plots in VegaLite. I want to display the plots alongside each other in a pluto notebook. The standard way to do this would be to combine the plots as below Plots.plot(plot1, plot2, layout = (2,1)) but that …

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## [SLURM manager: one node with multiple tasks](https://discourse.julialang.org/t/slurm-manager-one-node-with-multiple-tasks/124173)

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**Author:** [@kerim](https://discourse.julialang.org/u/kerim)\
**Replies:** 2\
**Last updated:** [December 28, 2024, 11:45am UTC](https://discourse.julialang.org/t/slurm-manager-one-node-with-multiple-tasks/124173 "2024-12-28T11:45:25Z")

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Hi, I have access to a single node with many 24 cores. I want Julia to treat that node as 4 workers with 6 cores per each worker. My attempt is: using Distributed, ClusterManagers addprocs(SlurmManager(1), nodes=1, n…

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## [Redirect stdout, stderr to string/stream C++ (embedded)](https://discourse.julialang.org/t/redirect-stdout-stderr-to-string-stream-c-embedded/124210)

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**Author:** [@Nelson-numerical-sof](https://discourse.julialang.org/u/Nelson-numerical-sof)\
**Replies:** 7\
**Last updated:** [December 27, 2024, 11:21pm UTC](https://discourse.julialang.org/t/redirect-stdout-stderr-to-string-stream-c-embedded/124210 "2024-12-27T23:21:09Z")

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Hi, I am currently a newbie on julia I try to redirect all outputs stderr, stdout to C/C++ from julia Currently I do and it seems to work: # Create custom IO buffer const io = IOBuffer() Ba…

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## [Don't understand why code runs out of memory and crashes](https://discourse.julialang.org/t/dont-understand-why-code-runs-out-of-memory-and-crashes/123559)

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**Author:** [@Davide98888](https://discourse.julialang.org/u/Davide98888)\
**Replies:** 29\
**Last updated:** [December 27, 2024, 9:42pm UTC](https://discourse.julialang.org/t/dont-understand-why-code-runs-out-of-memory-and-crashes/123559 "2024-12-27T21:42:15Z")

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Hello all We are having a fantastic experience with Julia, but then had a confusing experience. I am doing a simulation study, multithreaded, and eventually Julia runs out of memory and crashes. This happens especially …

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## [Dark- and light-mode images in documenter](https://discourse.julialang.org/t/dark-and-light-mode-images-in-documenter/124214)

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**Author:** [@moble](https://discourse.julialang.org/u/moble)\
**Replies:** 1\
**Last updated:** [December 27, 2024, 6:37pm UTC](https://discourse.julialang.org/t/dark-and-light-mode-images-in-documenter/124214 "2024-12-27T18:37:32Z")

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In github markdown, you can supply two images and include them both in the markdown, appending #gh-dark-mode-only or #gh-light-mode-only to the end of the image url and the appropriate one will display, depending on whet…

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## [Scaling issue (probably) while solving simple PINN problem](https://discourse.julialang.org/t/scaling-issue-probably-while-solving-simple-pinn-problem/124183)

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**Author:** [@nico](https://discourse.julialang.org/u/nico)\
**Replies:** 3\
**Last updated:** [December 27, 2024, 4:04pm UTC](https://discourse.julialang.org/t/scaling-issue-probably-while-solving-simple-pinn-problem/124183 "2024-12-27T16:04:14Z")

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Hi All! I am trying to solve a simple ODE with the PINN technology. There might be better ways to do that, but I am using it to test and understand few practical things. This code worked perfectly as long as the probl…

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## [Ccall with a C struct containing a pointer](https://discourse.julialang.org/t/ccall-with-a-c-struct-containing-a-pointer/124036)

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**Author:** [@luke-kiernan](https://discourse.julialang.org/u/luke-kiernan)\
**Replies:** 8\
**Last updated:** [December 27, 2024, 3:55pm UTC](https://discourse.julialang.org/t/ccall-with-a-c-struct-containing-a-pointer/124036 "2024-12-27T15:55:02Z")

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I’m writing a Julia interface for a C library. I have a C struct containing C-style array. I’ve wrapped said struct in Julia like so: mutable struct Example data::Ptr{Int64} # in the C, this is an array. end x = Int6…

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## [How to broadcast this function call?](https://discourse.julialang.org/t/how-to-broadcast-this-function-call/124190)

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**Author:** [@homocomputeris](https://discourse.julialang.org/u/homocomputeris)\
**Replies:** 6\
**Last updated:** [December 27, 2024, 2:58pm UTC](https://discourse.julialang.org/t/how-to-broadcast-this-function-call/124190 "2024-12-27T14:58:00Z")

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I want to broadcast the function g(u,t) over the argument u: module mwe t = 1.0 xs = rand(4) u = sin.(xs) # therefore, length(xs) is always equal to length(u) function Φ(x, t) return 2 \* exp(t) + exp(t) \* (1 - x) …

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## [Palindrome](https://discourse.julialang.org/t/palindrome/124054)

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**Author:** [@hack3rcon](https://discourse.julialang.org/u/hack3rcon)\
**Replies:** 19\
**Last updated:** [December 27, 2024, 6:20am UTC](https://discourse.julialang.org/t/palindrome/124054 "2024-12-27T06:20:14Z")

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Hello, I want to write a program that determines whether a sentence is a palindrome or not. I wrote the following program and it works, but I want to know if this piece of code is flawed from a programming science persp…

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## [Nested C structs, alignment, and "do not copy fields over"](https://discourse.julialang.org/t/nested-c-structs-alignment-and-do-not-copy-fields-over/124191)

<div class="topic-metadata">

**Author:** [@luke-kiernan](https://discourse.julialang.org/u/luke-kiernan)\
**Replies:** 5\
**Last updated:** [December 26, 2024, 11:37pm UTC](https://discourse.julialang.org/t/nested-c-structs-alignment-and-do-not-copy-fields-over/124191 "2024-12-26T23:37:46Z")

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I’m writing a Julia interface for a C library. I have two nested C-style structs, where the inner is used by-value. Thes docs say “declare an isbits struct,” but the inner C struct stores pointers, so that isn’t an optio…

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## [Can not add FixedEffectsModels package](https://discourse.julialang.org/t/can-not-add-fixedeffectsmodels-package/124193)

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**Author:** [@sb\_ali](https://discourse.julialang.org/u/sb_ali)\
**Replies:** 5\
**Last updated:** [December 26, 2024, 7:52pm UTC](https://discourse.julialang.org/t/can-not-add-fixedeffectsmodels-package/124193 "2024-12-26T19:52:53Z")

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I was trying add package FixedEffectsModels. but it says, ERROR: The following package names could not be resolved: FixedEffectsModels (not found in project, manifest or registry) I updated my Julia, still it is show…

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