# Latest

**URL:** https://discourse.julialang.org/latest.md?page=418

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

**Page:** 419

---

## [Quantum Simulation in Julia](https://discourse.julialang.org/t/quantum-simulation-in-julia/113829)

<div class="topic-metadata">

**Author:** [@Kamran](https://discourse.julialang.org/u/Kamran)\
**Replies:** 14\
**Last updated:** [May 5, 2024, 12:31am UTC](https://discourse.julialang.org/t/quantum-simulation-in-julia/113829 "2024-05-05T00:31:53Z")

</div>

I am facing Problem in Simulation can anyone help me to solve a small problem

---

## [Get the actual type from an Expr representing a type](https://discourse.julialang.org/t/get-the-actual-type-from-an-expr-representing-a-type/113848)

<div class="topic-metadata">

**Author:** [@mrufsvold](https://discourse.julialang.org/u/mrufsvold)\
**Replies:** 2\
**Last updated:** [May 4, 2024, 11:42pm UTC](https://discourse.julialang.org/t/get-the-actual-type-from-an-expr-representing-a-type/113848 "2024-05-04T23:42:50Z")

</div>

I think this may be the question being asked here, but it wasn’t resolved. I am writing a macro that manipulates the signature of a function. I want to know if an argument is annotated with a subtype of a type owned by …

---

## [Package in julia for solving optimization problems with cubic objective function](https://discourse.julialang.org/t/package-in-julia-for-solving-optimization-problems-with-cubic-objective-function/113055)

<div class="topic-metadata">

**Author:** [@heiwie](https://discourse.julialang.org/u/heiwie)\
**Replies:** 24\
**Last updated:** [May 4, 2024, 9:46pm UTC](https://discourse.julialang.org/t/package-in-julia-for-solving-optimization-problems-with-cubic-objective-function/113055 "2024-05-04T21:46:27Z")

</div>

Hello, I am trying to solve an optimization problem which looks like this: @objective(model, Max, sum(beta\_2\[n\] \* node\_info\[2\]\[1\]\[n\]\[1\] \* prod\_levels\[2\]\[1\]\[n\] \* uncon\_probs\[2\]\[1\]\[n\] for n in 1:num\_nodes) …

---

## [How to convert a Julia 3D array to a Python 3D list](https://discourse.julialang.org/t/how-to-convert-a-julia-3d-array-to-a-python-3d-list/113840)

<div class="topic-metadata">

**Author:** [@heiwie](https://discourse.julialang.org/u/heiwie)\
**Replies:** 5\
**Last updated:** [May 4, 2024, 6:52pm UTC](https://discourse.julialang.org/t/how-to-convert-a-julia-3d-array-to-a-python-3d-list/113840 "2024-05-04T18:52:33Z")

</div>

I have a Julia 3D array on the format Vector{Vector{Vector{Float64}}} and I am wondering how I can convert it into a 3D list in Python with the same indexing. Thanks for any help!

---

## [Classical Hypothesis tests: Wald, LR, LM](https://discourse.julialang.org/t/classical-hypothesis-tests-wald-lr-lm/39575)

<div class="topic-metadata">

**Author:** [@Albert\_Zevelev](https://discourse.julialang.org/u/Albert_Zevelev)\
**Replies:** 10\
**Last updated:** [May 4, 2024, 6:34pm UTC](https://discourse.julialang.org/t/classical-hypothesis-tests-wald-lr-lm/39575 "2024-05-04T18:34:35Z")

</div>

I was able to code up the LR & Wald tests. I need help w/ the score test. Does anyone know how to obtain the loglik functions after glm? using DataFrames, GLM, Distributions n=7; k=1; X=randn(n,k); β=\[2 ;-4\]; σ\_e = 10…

---

## [Announcing our 2024 GSoC & JSoC Fellows!](https://discourse.julialang.org/t/announcing-our-2024-gsoc-jsoc-fellows/113842)

<div class="topic-metadata">

**Author:** [@TheCedarPrince](https://discourse.julialang.org/u/TheCedarPrince)\
**Replies:** 0\
**Last updated:** [May 4, 2024, 5:32pm UTC](https://discourse.julialang.org/t/announcing-our-2024-gsoc-jsoc-fellows/113842 "2024-05-04T17:32:55Z")

</div>

Hi folks! We’ve written up a little blog post for the Julia website sharing about the new projects for this year’s Google Summer of Code & Julia Summer of Code cohorts! Follow the link to check them out! A huge congratu…

---

## [Single Day JuliaCon Tickets are now available](https://discourse.julialang.org/t/single-day-juliacon-tickets-are-now-available/113839)

<div class="topic-metadata">

**Author:** [@mkitti](https://discourse.julialang.org/u/mkitti)\
**Replies:** 0\
**Last updated:** [May 4, 2024, 4:45pm UTC](https://discourse.julialang.org/t/single-day-juliacon-tickets-are-now-available/113839 "2024-05-04T16:45:53Z")

</div>

JuliaCon 2024 tickets for individual days are now available. With the release of the JuliaCon 2024 Schedule you can now get tickets for one or two days. You can now purchase a ticket for Tuesday (workshops)- €300 Wedn…

---

## [MTK & NonlinearSolve](https://discourse.julialang.org/t/mtk-nonlinearsolve/113834)

<div class="topic-metadata">

**Author:** [@BLI](https://discourse.julialang.org/u/BLI)\
**Replies:** 0\
**Last updated:** [May 4, 2024, 3:29pm UTC](https://discourse.julialang.org/t/mtk-nonlinearsolve/113834 "2024-05-04T15:29:56Z")

</div>

I have converted a Python function to Julia which involves: kwargs to specify units, correlations, etc. unit conversion solving an implicit equation My Julia conversion works, but I’m thinking of converting the functi…

---

## [Custom optimized hash tables with UInt64 keys, lower level than Dict for ultra speed](https://discourse.julialang.org/t/custom-optimized-hash-tables-with-uint64-keys-lower-level-than-dict-for-ultra-speed/113831)

<div class="topic-metadata">

**Author:** [@0x0f0f0f](https://discourse.julialang.org/u/0x0f0f0f)\
**Replies:** 5\
**Last updated:** [May 4, 2024, 2:40pm UTC](https://discourse.julialang.org/t/custom-optimized-hash-tables-with-uint64-keys-lower-level-than-dict-for-ultra-speed/113831 "2024-05-04T14:40:57Z")

</div>

In Metatheory.jl we have e-graphs, which are basically made of some Dicts. We are encountering some performance bottlenecks because of the implementation of Dict, and we realized that optimized data structures could go a…

---

## [Taking gradient to update a Flux.jl CNN](https://discourse.julialang.org/t/taking-gradient-to-update-a-flux-jl-cnn/113822)

<div class="topic-metadata">

**Author:** [@mward19](https://discourse.julialang.org/u/mward19)\
**Replies:** 2\
**Last updated:** [May 4, 2024, 2:21pm UTC](https://discourse.julialang.org/t/taking-gradient-to-update-a-flux-jl-cnn/113822 "2024-05-04T14:21:39Z")

</div>

Hello, I am new to Julia and Flux.jl, and I’ve been working on some toy problems to learn. I have been struggling to get my networks to train – I have yet to get Flux.train! to work, so I’ve been writing my gradient desc…

---

## [Equivalent to pipx (install Julia apps)](https://discourse.julialang.org/t/equivalent-to-pipx-install-julia-apps/113826)

<div class="topic-metadata">

**Author:** [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Replies:** 5\
**Last updated:** [May 4, 2024, 12:02pm UTC](https://discourse.julialang.org/t/equivalent-to-pipx-install-julia-apps/113826 "2024-05-04T12:02:05Z")

</div>

Is there an equivalent to pipx for Julia apps? pipx makes it so easy to install Python apps, mainly intended for console apps, but also works with gui apps. Example: pipx install mnemosyne-proj on Ubuntu installs the…

---

## [Experience report after finishing a (reasonably substantial) Julia project in 2024](https://discourse.julialang.org/t/experience-report-after-finishing-a-reasonably-substantial-julia-project-in-2024/113148)

<div class="topic-metadata">

**Author:** [@rongcuid](https://discourse.julialang.org/u/rongcuid)\
**Replies:** 80\
**Last updated:** [May 4, 2024, 11:23am UTC](https://discourse.julialang.org/t/experience-report-after-finishing-a-reasonably-substantial-julia-project-in-2024/113148 "2024-05-04T11:23:29Z")

</div>

Originally published on Reddit, got advised to post it here as well. TL;DR Great community. Excellent at expressing “math”. Very fast language. Almost great REPL. Immature ecosystem. Inconvenient debugging. Bad code org…

---

## [Coupled PDE solver](https://discourse.julialang.org/t/coupled-pde-solver/113636)

<div class="topic-metadata">

**Author:** [@avishipoddar](https://discourse.julialang.org/u/avishipoddar)\
**Replies:** 1\
**Last updated:** [May 4, 2024, 10:45am UTC](https://discourse.julialang.org/t/coupled-pde-solver/113636 "2024-05-04T10:45:16Z")

</div>

I am trying to solve a coupled linear pde I have attached my code below using DifferentialEquations using FiniteDifferences Define your system of coupled linear partial differential equations function coupled\_pdes(du…

---

## [Database backed for DataFrames](https://discourse.julialang.org/t/database-backed-for-dataframes/94768)

<div class="topic-metadata">

**Author:** [@ayushpatnaikgit](https://discourse.julialang.org/u/ayushpatnaikgit)\
**Replies:** 6\
**Last updated:** [May 4, 2024, 3:05am UTC](https://discourse.julialang.org/t/database-backed-for-dataframes/94768 "2024-05-04T03:05:54Z")

</div>

Any package in Julia like R’s dbplyr? dbplyr allows you to use remote database tables as if they are in-memory data frames by automatically converting dplyr code into SQL. I want to do the same with DataFrames and SQL.

---

## [Error updating Julia to 1.10.3 with UpdateJulia on mac?](https://discourse.julialang.org/t/error-updating-julia-to-1-10-3-with-updatejulia-on-mac/113703)

<div class="topic-metadata">

**Author:** [@phantom](https://discourse.julialang.org/u/phantom)\
**Replies:** 12\
**Last updated:** [May 4, 2024, 12:37am UTC](https://discourse.julialang.org/t/error-updating-julia-to-1-10-3-with-updatejulia-on-mac/113703 "2024-05-04T00:37:47Z")

</div>

Hi I’m currently using Julia Version 1.10.2 on a macOS (arm64) Apple M1 Max I get the following error when trying to update julia to 1.10.3 julia\> using UpdateJulia julia\> update\_julia() ERROR: No valid download for …

---

## [Jldoctest: number of elements printed for array](https://discourse.julialang.org/t/jldoctest-number-of-elements-printed-for-array/113794)

<div class="topic-metadata">

**Author:** [@lmiq](https://discourse.julialang.org/u/lmiq)\
**Replies:** 12\
**Last updated:** [May 4, 2024, 12:06am UTC](https://discourse.julialang.org/t/jldoctest-number-of-elements-printed-for-array/113794 "2024-05-04T00:06:21Z")

</div>

In a docstring like: \`\`\`jldoctest julia\> x = rand(1000) 1000-element Vector{Float64}: 0.9193285028224774 0.35444797029663266 0.1201916693868853 0.35371426411293694 0.11668489865605236 0.6506991967008628 ⋮ 0.5180…

---

## [Collapse duplicate rows in Julia matrix](https://discourse.julialang.org/t/collapse-duplicate-rows-in-julia-matrix/113817)

<div class="topic-metadata">

**Author:** [@Santiago\_Lopez](https://discourse.julialang.org/u/Santiago_Lopez)\
**Replies:** 2\
**Last updated:** [May 3, 2024, 9:45pm UTC](https://discourse.julialang.org/t/collapse-duplicate-rows-in-julia-matrix/113817 "2024-05-03T21:45:21Z")

</div>

I have a matrix U = vcat(s, e, p) of the form 3167×2 Matrix{Int64}: 1 1 1 1 1 1 1 1 1 2 1 2 1 2 1 3 1 3 1 3 3 2 3 2 3 3 ⋮ 962 5 962 5 962 5…

---

## [Finding functions](https://discourse.julialang.org/t/finding-functions/105285)

<div class="topic-metadata">

**Author:** [@panos.asproulis](https://discourse.julialang.org/u/panos.asproulis)\
**Replies:** 13\
**Last updated:** [May 3, 2024, 9:29pm UTC](https://discourse.julialang.org/t/finding-functions/105285 "2024-05-03T21:29:08Z")

</div>

One issue I have with Julia is remembering the name of functions and what they do. In a typical OOP language and IDE/editor typing the name of an object and then the dot character a pop-up window will produce a list of a…

---

## [Why does \`let\` allow comma-separated assignments?](https://discourse.julialang.org/t/why-does-let-allow-comma-separated-assignments/113812)

<div class="topic-metadata">

**Author:** [@MilesCranmer](https://discourse.julialang.org/u/MilesCranmer)\
**Replies:** 7\
**Last updated:** [May 3, 2024, 9:06pm UTC](https://discourse.julialang.org/t/why-does-let-allow-comma-separated-assignments/113812 "2024-05-03T21:06:46Z")

</div>

This is something I’ve always wondered… Why does a let block allow comma-separated assignments? let x = 1, y = 2, z = 3 (x, y, z) end As far as I can tell, this is completely identical to let x = 1; y = 2; z = 3 …

---

## [Error when updating Julia via UpdateJulia](https://discourse.julialang.org/t/error-when-updating-julia-via-updatejulia/91046)

<div class="topic-metadata">

**Author:** [@phantom](https://discourse.julialang.org/u/phantom)\
**Replies:** 9\
**Last updated:** [May 3, 2024, 9:01pm UTC](https://discourse.julialang.org/t/error-when-updating-julia-via-updatejulia/91046 "2024-05-03T21:01:02Z")

</div>

I am currently using Julia version 1.7.2. on macOS Monterey with an arm processor, When I tried updating to 1.8.3 via the UpdateJulia package I received the following permission error /dev/disk4 GUID\_partit…

---

## [Jupyter-notebook cannot connect Julia kernel](https://discourse.julialang.org/t/jupyter-notebook-cannot-connect-julia-kernel/113814)

<div class="topic-metadata">

**Author:** [@appletree999](https://discourse.julialang.org/u/appletree999)\
**Replies:** 2\
**Last updated:** [May 3, 2024, 8:53pm UTC](https://discourse.julialang.org/t/jupyter-notebook-cannot-connect-julia-kernel/113814 "2024-05-03T20:53:10Z")

</div>

Hi, I installed Julia both using directions here Installation · IJulia and using conda-forge. But none of this works for jupyter-notebook, as shown in the picture: Errors from terminal: WARNING: Error during initial…

---

## [Converting Float32 values back to Float64 without introducing nonzero digits at the end?](https://discourse.julialang.org/t/converting-float32-values-back-to-float64-without-introducing-nonzero-digits-at-the-end/113810)

<div class="topic-metadata">

**Author:** [@Norman](https://discourse.julialang.org/u/Norman)\
**Replies:** 2\
**Last updated:** [May 3, 2024, 6:59pm UTC](https://discourse.julialang.org/t/converting-float32-values-back-to-float64-without-introducing-nonzero-digits-at-the-end/113810 "2024-05-03T18:59:17Z")

</div>

I hope this question is not silly. When converting a Float32 value back to Float64, I get something like this: julia\> Float64(Float32(0.1)) 0.10000000149011612 Is there a way to obtain exactly 0.1 without having the no…

---

## [\[Vaporware/RFC\] Width-Qualified FixedPointNumbers](https://discourse.julialang.org/t/vaporware-rfc-width-qualified-fixedpointnumbers/113774)

<div class="topic-metadata">

**Author:** [@kimikage](https://discourse.julialang.org/u/kimikage)\
**Replies:** 3\
**Last updated:** [May 3, 2024, 7:06pm UTC](https://discourse.julialang.org/t/vaporware-rfc-width-qualified-fixedpointnumbers/113774 "2024-05-03T19:06:07Z")

</div>

First of all, I apologize to you all for the clickbait. FixedPointNumbers.jl v0.8.5 is being prepared for release. Edit: CANCELED That is 77% of what I want to announce. Let’s talk about the other 33%. WidthQualified…

---

## [Parsing Julia code to separate symbols based on scoping and create a symbol table](https://discourse.julialang.org/t/parsing-julia-code-to-separate-symbols-based-on-scoping-and-create-a-symbol-table/113809)

<div class="topic-metadata">

**Author:** [@Akhil\_Akkapelli](https://discourse.julialang.org/u/Akhil_Akkapelli)\
**Replies:** 1\
**Last updated:** [May 3, 2024, 7:00pm UTC](https://discourse.julialang.org/t/parsing-julia-code-to-separate-symbols-based-on-scoping-and-create-a-symbol-table/113809 "2024-05-03T19:00:39Z")

</div>

I have a quote block in Julia containing functions, modules, and etc. Assuming that quote block is in Main module and Main module does not have these symbols with same names. I want to separate the symbols based on their…

---

## [Do you use PkgTemplates for personal projects?](https://discourse.julialang.org/t/do-you-use-pkgtemplates-for-personal-projects/113780)

<div class="topic-metadata">

**Author:** [@greatpet](https://discourse.julialang.org/u/greatpet)\
**Replies:** 3\
**Last updated:** [May 3, 2024, 6:30pm UTC](https://discourse.julialang.org/t/do-you-use-pkgtemplates-for-personal-projects/113780 "2024-05-03T18:30:20Z")

</div>

For personal projects which likely won’t become a published package, do you use Pkg.generate or the full-fledged PkgTemplates.jl? The latter has nice things like setting up the CI, but I’m not sure if I should use it for…

---

## [How to exit from loop on keyboard button pressing?](https://discourse.julialang.org/t/how-to-exit-from-loop-on-keyboard-button-pressing/113808)

<div class="topic-metadata">

**Author:** [@andrey2185](https://discourse.julialang.org/u/andrey2185)\
**Replies:** 0\
**Last updated:** [May 3, 2024, 5:59pm UTC](https://discourse.julialang.org/t/how-to-exit-from-loop-on-keyboard-button-pressing/113808 "2024-05-03T17:59:27Z")

</div>

Hello, how to exit from loop on keyboard button pressing? I see two ways: catch InterruptException or this: function main\_loop() println("Press 'Enter' to stop.") task = Threads.@spawn readline(stdin) while true …

---

## [Plots.jl package ceases to work](https://discourse.julialang.org/t/plots-jl-package-ceases-to-work/113798)

<div class="topic-metadata">

**Author:** [@torein](https://discourse.julialang.org/u/torein)\
**Replies:** 9\
**Last updated:** [May 3, 2024, 5:36pm UTC](https://discourse.julialang.org/t/plots-jl-package-ceases-to-work/113798 "2024-05-03T17:36:56Z")

</div>

Hi there, I have been using Julia 1.82 on Windows 10 for nearly two years. Up til now, the Plots.jl package has funcioned very well. Suddenly, however, the package fails to work. Whenever I run a code that includes…

---

## [Error: Installation of Plots](https://discourse.julialang.org/t/error-installation-of-plots/100318)

<div class="topic-metadata">

**Author:** [@ilex](https://discourse.julialang.org/u/ilex)\
**Replies:** 1\
**Last updated:** [May 3, 2024, 4:38pm UTC](https://discourse.julialang.org/t/error-installation-of-plots/100318 "2024-05-03T16:38:28Z")

</div>

Trying to install Plots following error occures: julia\> import Pkg; julia\> Pkg.add(“Plots”) Updating registry at C:\\Users\\angel.naya-geiger\\Juliawin\\userdata\\.julia\\registries\\General.toml Resolving package versions…

---

## [How to extract the Std. Error of a linear regression model by GLM?](https://discourse.julialang.org/t/how-to-extract-the-std-error-of-a-linear-regression-model-by-glm/113793)

<div class="topic-metadata">

**Author:** [@Shayan](https://discourse.julialang.org/u/Shayan)\
**Replies:** 3\
**Last updated:** [May 3, 2024, 3:10pm UTC](https://discourse.julialang.org/t/how-to-extract-the-std-error-of-a-linear-regression-model-by-glm/113793 "2024-05-03T15:10:39Z")

</div>

How to extract the Std. Error of a linear regression model by GLM.jl? julia\> using GLM julia\> x = rand(10); y = rand(10); julia\> lr = lm(@formula(y~x), (;x, y)) StatsModels.TableRegressionModel{LinearModel{GLM.LmResp{…

---

## [Convergence of RK4 solver](https://discourse.julialang.org/t/convergence-of-rk4-solver/113770)

<div class="topic-metadata">

**Author:** [@Pranav\_Vinod](https://discourse.julialang.org/u/Pranav_Vinod)\
**Replies:** 5\
**Last updated:** [May 3, 2024, 2:40pm UTC](https://discourse.julialang.org/t/convergence-of-rk4-solver/113770 "2024-05-03T14:40:32Z")

</div>

Hi, I am working on solving some differential equations and noticed some discrepancies in the convergence of the RK4 solver. I tested the error by finding the difference between the solver solution and analytical result…

[Previous page](https://discourse.julialang.org/latest.md?page=417)

[Next page](https://discourse.julialang.org/latest.md?page=419)