# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1033

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

**Page:** 1034

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## [How do I get CI to use the nightly version of Julia for Documenter-produced documentation?](https://discourse.julialang.org/t/how-do-i-get-ci-to-use-the-nightly-version-of-julia-for-documenter-produced-documentation/81467)

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**Author:** [@Joris\_Pinkse](https://discourse.julialang.org/u/Joris_Pinkse)\
**Replies:** 1\
**Last updated:** [May 22, 2022, 5:57pm UTC](https://discourse.julialang.org/t/how-do-i-get-ci-to-use-the-nightly-version-of-julia-for-documenter-produced-documentation/81467 "2022-05-22T17:57:19Z")

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How do I get CI to use the nightly version of Julia for Documenter-produced documentation? It currently uses 1.7.2 but my package requires 1.8beta3. I can’t figure out how to do it. (I’d asked a similar question on th…

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## [Julia user's guide for the positive semidefinite program with variables in {-1,1}](https://discourse.julialang.org/t/julia-users-guide-for-the-positive-semidefinite-program-with-variables-in-1-1/81460)

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**Author:** [@Huyen26n](https://discourse.julialang.org/u/Huyen26n)\
**Replies:** 1\
**Last updated:** [May 22, 2022, 5:31pm UTC](https://discourse.julialang.org/t/julia-users-guide-for-the-positive-semidefinite-program-with-variables-in-1-1/81460 "2022-05-22T17:31:25Z")

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Dear all, I am using Julia for the first time to work on the positive semidefinite program. I’m trying to solve the PSD with variables in {-1,1}. I don’t understand how to write objective functions or variables, … I wis…

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## [\[ANN\] Timers.jl tic() toc() and accurate delays](https://discourse.julialang.org/t/ann-timers-jl-tic-toc-and-accurate-delays/81461)

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**Author:** [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Replies:** 3\
**Last updated:** [May 22, 2022, 3:37pm UTC](https://discourse.julialang.org/t/ann-timers-jl-tic-toc-and-accurate-delays/81461 "2022-05-22T15:37:53Z")

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The package GitHub - ufechner7/Timers.jl: Timers for Julia provides the helper functions tic() and \`toc() that where removed from Julia in version 1.0. I still find them very useful, for example to measure the time unti…

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## [Google Summer of Code 2022 Projects Announced!](https://discourse.julialang.org/t/google-summer-of-code-2022-projects-announced/81445)

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**Author:** [@logankilpatrick](https://discourse.julialang.org/u/logankilpatrick)\
**Replies:** 3\
**Last updated:** [May 22, 2022, 3:31pm UTC](https://discourse.julialang.org/t/google-summer-of-code-2022-projects-announced/81445 "2022-05-22T15:31:11Z")

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Hey all, We are really excited to share that this year we will have 21 contributors participate in Google Summer of code with the Julia Language (2 projects will be under the JSoC umbrella) and 11 more through NumFOCUS …

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## [Question about Julia zeros matrix?](https://discourse.julialang.org/t/question-about-julia-zeros-matrix/81350)

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**Author:** [@Raymond](https://discourse.julialang.org/u/Raymond)\
**Replies:** 12\
**Last updated:** [May 22, 2022, 3:06pm UTC](https://discourse.julialang.org/t/question-about-julia-zeros-matrix/81350 "2022-05-22T15:06:58Z")

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Dear all, In matlab, we can add complex values into zeros matrix, but in Julia I cannot .Can you help me to modify my codes to add complex values into zeros matrix in Julia? This is the matlab code. \>\> A = zeros(2, 2)…

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## [DataFrames - reduce allocations and improve speed](https://discourse.julialang.org/t/dataframes-reduce-allocations-and-improve-speed/81380)

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**Author:** [@bojusemo](https://discourse.julialang.org/u/bojusemo)\
**Replies:** 5\
**Last updated:** [May 22, 2022, 2:52pm UTC](https://discourse.julialang.org/t/dataframes-reduce-allocations-and-improve-speed/81380 "2022-05-22T14:52:06Z")

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Hello folks, I have two huge data frames (described below) and I’m running my\_module.f5(df1, df2) based on the module and functions described below. The code works with small data frames, but when I run it with those bi…

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## [BoundsError trying to solve DDEProblem](https://discourse.julialang.org/t/boundserror-trying-to-solve-ddeproblem/81441)

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**Author:** [@Achraf\_el\_fadli](https://discourse.julialang.org/u/Achraf_el_fadli)\
**Replies:** 6\
**Last updated:** [May 22, 2022, 1:30pm UTC](https://discourse.julialang.org/t/boundserror-trying-to-solve-ddeproblem/81441 "2022-05-22T13:30:08Z")

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function f(du,u,h,p,t) k1,k2,tau=p hist=h(p,t-tau)\[0\] du\[0\]=u0 end h(p,t)=ones(1) tau=7 lags=\[tau\] k1=0.5;k2=0.1 p=k1,k2,tau span=(0.0,10.0) u0=\[1.0\] prob = DDEProblem(f,u0,h,span,p; constant\_lags=lags) sol=…

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## [Printing in a background process](https://discourse.julialang.org/t/printing-in-a-background-process/81453)

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**Author:** [@FedeClaudi](https://discourse.julialang.org/u/FedeClaudi)\
**Replies:** 10\
**Last updated:** [May 22, 2022, 12:51pm UTC](https://discourse.julialang.org/t/printing-in-a-background-process/81453 "2022-05-22T12:51:07Z")

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Hi everyone, I’m trying to do something that feels like should be easy but I can’t figure it out. Basically, let’s say I have a function (doer) which takes a while to run and I want to have another function printer pri…

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## [Issue with Local Sensitivites and dt \<= dtmin](https://discourse.julialang.org/t/issue-with-local-sensitivites-and-dt-dtmin/81426)

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**Author:** [@xztt](https://discourse.julialang.org/u/xztt)\
**Replies:** 4\
**Last updated:** [May 22, 2022, 12:14pm UTC](https://discourse.julialang.org/t/issue-with-local-sensitivites-and-dt-dtmin/81426 "2022-05-22T12:14:33Z")

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Hi, I am trying to calculate the local sensitivities for a large circulation model (Shi 2006) I am Importing the model using CellML.jl when I define an ODEproblem and simulate the solution appears fine and also when pe…

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## [Linting stage in CI pipeline - which to use and how?](https://discourse.julialang.org/t/linting-stage-in-ci-pipeline-which-to-use-and-how/80697)

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**Author:** [@FireCrumb](https://discourse.julialang.org/u/FireCrumb)\
**Replies:** 13\
**Last updated:** [May 22, 2022, 10:30am UTC](https://discourse.julialang.org/t/linting-stage-in-ci-pipeline-which-to-use-and-how/80697 "2022-05-22T10:30:04Z")

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Hello, I have a CI/CD pipeline in GitLab, and I want to run a lintig stage to fail the build on detected bugs. What is the proper way to do this? Found Lint.jl but it’s abandoned (last update 2019) Found StaticLint.jl …

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## [What does the REPL keybinding ctrl + \< + t correspond to?](https://discourse.julialang.org/t/what-does-the-repl-keybinding-ctrl-t-correspond-to/81424)

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**Author:** [@jishnub](https://discourse.julialang.org/u/jishnub)\
**Replies:** 2\
**Last updated:** [May 22, 2022, 10:14am UTC](https://discourse.julialang.org/t/what-does-the-repl-keybinding-ctrl-t-correspond-to/81424 "2022-05-22T10:14:42Z")

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Because of a weird keyboard layout, I often end up pressing ctrl + \< + t instead of ctrl + shift + t, and I obtain the following output: julia\> \<┌ Error: Error in the keymap │ exception = │ EOFError: read end of fi…

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## [Problem after discretizing a PDE to ODE and solve with DifferentialEquations.jl](https://discourse.julialang.org/t/problem-after-discretizing-a-pde-to-ode-and-solve-with-differentialequations-jl/81451)

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**Author:** [@Molox](https://discourse.julialang.org/u/Molox)\
**Replies:** 1\
**Last updated:** [May 22, 2022, 9:42am UTC](https://discourse.julialang.org/t/problem-after-discretizing-a-pde-to-ode-and-solve-with-differentialequations-jl/81451 "2022-05-22T09:42:01Z")

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Hi, I was reading https://www.stochasticlifestyle.com/solving-systems-stochastic-pdes-using-gpus-julia/ And I would like to know if it is possible to discretize a 4th derivative PDE to ODE: ddt(u) = ddddx(u) and solve w…

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## [How to set up toolbar using Gtk.jl's GtkAction with custom toolbar icons?](https://discourse.julialang.org/t/how-to-set-up-toolbar-using-gtk-jls-gtkaction-with-custom-toolbar-icons/81457)

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**Author:** [@fjg](https://discourse.julialang.org/u/fjg)\
**Replies:** 0\
**Last updated:** [May 22, 2022, 9:04am UTC](https://discourse.julialang.org/t/how-to-set-up-toolbar-using-gtk-jls-gtkaction-with-custom-toolbar-icons/81457 "2022-05-22T09:04:17Z")

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using Gtk using Gtk.ShortNames win = GtkWindow( “toolbar”, 800, 600) file = GtkMenuItem(“\_File”) filemenu = GtkMenu(file) new\_ = GtkMenuItem(“New”) push!(filemenu, new\_) mb = GtkMenuBar() push!(mb, file) g = Gtk…

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## [Type of composition of functions is not predictable](https://discourse.julialang.org/t/type-of-composition-of-functions-is-not-predictable/81446)

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**Author:** [@Veenty](https://discourse.julialang.org/u/Veenty)\
**Replies:** 1\
**Last updated:** [May 22, 2022, 6:08am UTC](https://discourse.julialang.org/t/type-of-composition-of-functions-is-not-predictable/81446 "2022-05-22T06:08:15Z")

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I’m trying to figure out why the type of this function is not predictable function η\_const(r, η\_) if r\>=1 return convert( typeof(r), 0.0) elseif r\<=0.8 return convert( typeof(r), 1.0) els…

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## [@everywhere and PackageCompiler build\_executable()](https://discourse.julialang.org/t/everywhere-and-packagecompiler-build-executable/16121)

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**Author:** [@waldoc](https://discourse.julialang.org/u/waldoc)\
**Replies:** 1\
**Last updated:** [May 21, 2022, 9:33am UTC](https://discourse.julialang.org/t/everywhere-and-packagecompiler-build-executable/16121 "2022-05-21T09:33:44Z")

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I am trying to build an executable using a package I created. The code makes use of pmap to run on multiple workers. I created a new module with the function name as per PackageCompiler recommendations and compiled with…

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## [Superexpressive Activation function (paper) and "Three Hidden Layers Are Enough" paper](https://discourse.julialang.org/t/superexpressive-activation-function-paper-and-three-hidden-layers-are-enough-paper/81336)

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**Author:** [@Palli](https://discourse.julialang.org/u/Palli)\
**Replies:** 1\
**Last updated:** [May 22, 2022, 1:25am UTC](https://discourse.julialang.org/t/superexpressive-activation-function-paper-and-three-hidden-layers-are-enough-paper/81336 "2022-05-22T01:25:15Z")

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I came across Superexpressive Activation functions, the elementary kind on arxiv, the paper on it is also at: A. Elementary Superexpressive Activations http://proceedings.mlr.press/v139/yarotsky21a/yarotsky21a.pdf we…

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## [\[sparse modelling\] Does JuMP automatically remove "uninfluent" variables from constraints/objective?](https://discourse.julialang.org/t/sparse-modelling-does-jump-automatically-remove-uninfluent-variables-from-constraints-objective/81366)

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**Author:** [@sylvaticus](https://discourse.julialang.org/u/sylvaticus)\
**Replies:** 6\
**Last updated:** [May 22, 2022, 12:13am UTC](https://discourse.julialang.org/t/sparse-modelling-does-jump-automatically-remove-uninfluent-variables-from-constraints-objective/81366 "2022-05-22T00:13:02Z")

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Hello, I am designing a non-linear model where some quantities depend from many variables, but only a few of them actually have a parameter that allow the dependent variable to play. The actual implementation is: quant…

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## [Understand why type stability depends on number of methods](https://discourse.julialang.org/t/understand-why-type-stability-depends-on-number-of-methods/81434)

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**Author:** [@bgctw](https://discourse.julialang.org/u/bgctw)\
**Replies:** 2\
**Last updated:** [May 22, 2022, 12:01am UTC](https://discourse.julialang.org/t/understand-why-type-stability-depends-on-number-of-methods/81434 "2022-05-22T00:01:50Z")

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I am reading the of Julia book of Kwong (@tk3369) and Karpinski 2020 and like to use the singleton type dispatch pattern. However, when I check type stability (on Julia 1.7.3), I find that it suddenly fails when more me…

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## [Make documentation for package under Julia 1.8beta3](https://discourse.julialang.org/t/make-documentation-for-package-under-julia-1-8beta3/81437)

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**Author:** [@Joris\_Pinkse](https://discourse.julialang.org/u/Joris_Pinkse)\
**Replies:** 0\
**Last updated:** [May 21, 2022, 9:53pm UTC](https://discourse.julialang.org/t/make-documentation-for-package-under-julia-1-8beta3/81437 "2022-05-21T21:53:05Z")

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I’m working on developing a new package that uses some features only available in Julia 1.8. It runs fine under the nightly, except that the documentation (Documenter) does not get deployed because the package requires …

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## [Why don't macros and modules also have backedges to allow "invalidating" dependent code?](https://discourse.julialang.org/t/why-dont-macros-and-modules-also-have-backedges-to-allow-invalidating-dependent-code/81408)

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**Author:** [@Benny](https://discourse.julialang.org/u/Benny)\
**Replies:** 0\
**Last updated:** [May 21, 2022, 10:07am UTC](https://discourse.julialang.org/t/why-dont-macros-and-modules-also-have-backedges-to-allow-invalidating-dependent-code/81408 "2022-05-21T10:07:32Z")

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Something cool that Julia does is method invalidation. When a method is compiled to a MethodInstance upon a call, assumptions like what methods are dispatched to and compile-time constants are baked in. When a function i…

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## [How to define and integrate a HamiltonianProblem?](https://discourse.julialang.org/t/how-to-define-and-integrate-a-hamiltonianproblem/81303)

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**Author:** [@cdawg](https://discourse.julialang.org/u/cdawg)\
**Replies:** 5\
**Last updated:** [May 21, 2022, 6:51pm UTC](https://discourse.julialang.org/t/how-to-define-and-integrate-a-hamiltonianproblem/81303 "2022-05-21T18:51:49Z")

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Dear friends. I have a hamiltonian for the cart and pole system which is a standard problem in RL. Lagrangian version shown here, I just legendre transformed it. I don’t need a full solution. I just want to step it forw…

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## [Plot image in memory how to get at a pixel on a line](https://discourse.julialang.org/t/plot-image-in-memory-how-to-get-at-a-pixel-on-a-line/81312)

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**Author:** [@anon69491625](https://discourse.julialang.org/u/anon69491625)\
**Replies:** 1\
**Last updated:** [May 21, 2022, 6:07pm UTC](https://discourse.julialang.org/t/plot-image-in-memory-how-to-get-at-a-pixel-on-a-line/81312 "2022-05-21T18:07:42Z")

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hi all I am thinking about how to access a memory location that represents a pixel on an image. So in the image below the first pixel of the first line or the first pixel of the 2nd row line. I’d like to keep it si…

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## [How to read without blocking](https://discourse.julialang.org/t/how-to-read-without-blocking/81409)

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**Author:** [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Replies:** 6\
**Last updated:** [May 21, 2022, 1:41pm UTC](https://discourse.julialang.org/t/how-to-read-without-blocking/81409 "2022-05-21T13:41:31Z")

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How can I read from an input device on Linux in a non-blocking way, perhaps with a timeout? I have this function: function read\_event(js::JSDevice) event = read(js.device, sizeof(JSEvent); all = false) if sizeo…

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## [From recursive to iterative](https://discourse.julialang.org/t/from-recursive-to-iterative/81411)

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**Author:** [@rocco\_sprmnt21](https://discourse.julialang.org/u/rocco_sprmnt21)\
**Replies:** 0\
**Last updated:** [May 21, 2022, 10:56am UTC](https://discourse.julialang.org/t/from-recursive-to-iterative/81411 "2022-05-21T10:56:06Z")

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Given a table nxn and a starting position, it is required to determine a sequence of steps / moves that allow you to go through all the cells once and only once. The allowed moves are those that move vertically and hori…

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## [Documentation about using anonymous and named functions with pmap](https://discourse.julialang.org/t/documentation-about-using-anonymous-and-named-functions-with-pmap/19337)

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**Author:** [@zsunberg](https://discourse.julialang.org/u/zsunberg)\
**Replies:** 9\
**Last updated:** [May 21, 2022, 8:23am UTC](https://discourse.julialang.org/t/documentation-about-using-anonymous-and-named-functions-with-pmap/19337 "2022-05-21T08:23:14Z")

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I noticed that anonymous functions behave differently from regular functions w.r.t. serialization and code availability on other processes. e.g., when julia is run with multiple processes, f(x) = x^2 pmap(f, 1:10) thro…

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## [How to track memory allocation in vscode](https://discourse.julialang.org/t/how-to-track-memory-allocation-in-vscode/81230)

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**Author:** [@jisutich](https://discourse.julialang.org/u/jisutich)\
**Replies:** 12\
**Last updated:** [May 21, 2022, 3:21am UTC](https://discourse.julialang.org/t/how-to-track-memory-allocation-in-vscode/81230 "2022-05-21T03:21:08Z")

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Hi, I recently have a small code which runs fast. But when I change the arguments the memory allocation grows quickly. I want to see where the memory allocation happens. I just find this https://github.com/JuliaCI/Cove…

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## [Module correctly loaded from LOAD\_PATH but still getting a dependencies warning](https://discourse.julialang.org/t/module-correctly-loaded-from-load-path-but-still-getting-a-dependencies-warning/58087)

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**Author:** [@essenciary](https://discourse.julialang.org/u/essenciary)\
**Replies:** 1\
**Last updated:** [May 21, 2022, 3:02am UTC](https://discourse.julialang.org/t/module-correctly-loaded-from-load-path-but-still-getting-a-dependencies-warning/58087 "2022-05-21T03:02:27Z")

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I have a folder added to LOAD\_PATH, and in this folder the TestsController.jl module. In another file I have using TestsController. Everything works as expected, but upon loading the app/script I’m getting a warning abou…

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## ["Warning: Package \_\_\_\_ does not have \_\_\_\_\_ in its dependencies" when Genie loaded but not in REPL](https://discourse.julialang.org/t/warning-package-does-not-have-in-its-dependencies-when-genie-loaded-but-not-in-repl/81404)

<div class="topic-metadata">

**Author:** [@andromodon](https://discourse.julialang.org/u/andromodon)\
**Replies:** 0\
**Last updated:** [May 21, 2022, 3:00am UTC](https://discourse.julialang.org/t/warning-package-does-not-have-in-its-dependencies-when-genie-loaded-but-not-in-repl/81404 "2022-05-21T03:00:53Z")

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I’m fairly new to Genie, but I created an app called “Jane” with a resource called TTIntervals: Here is the code I’m running as part of a route: push!(LOAD\_PATH, "src/resources/ttintervals") println("") @show LOAD\_PATH…

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## [Speed up a derivative calculation?](https://discourse.julialang.org/t/speed-up-a-derivative-calculation/80921)

<div class="topic-metadata">

**Author:** [@vshesh](https://discourse.julialang.org/u/vshesh)\
**Replies:** 10\
**Last updated:** [May 21, 2022, 2:04am UTC](https://discourse.julialang.org/t/speed-up-a-derivative-calculation/80921 "2022-05-21T02:04:41Z")

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Hi, I am trying to write a function to compute the derivative of a cost function. The cost function is used to express how good a distance function is at separating labeled data into its respective classes. I’m trying …

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## [Read Joystick from Julia](https://discourse.julialang.org/t/read-joystick-from-julia/81325)

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**Author:** [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Replies:** 22\
**Last updated:** [May 20, 2022, 11:42pm UTC](https://discourse.julialang.org/t/read-joystick-from-julia/81325 "2022-05-20T23:42:37Z")

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Hello, I would like to read a joystick on Linux to control my kite simulator (see: GitHub - aenarete/KiteViewers.jl: 3D viewer for airborne wind energy systems ). The following test on the command line works: jstest --…

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