# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1715

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

**Page:** 1716

---

## [Converting from Shell to Julia](https://discourse.julialang.org/t/converting-from-shell-to-julia/41531)

<div class="topic-metadata">

**Author:** [@siralfbaez](https://discourse.julialang.org/u/siralfbaez)\
**Replies:** 6\
**Last updated:** [June 17, 2020, 2:54am UTC](https://discourse.julialang.org/t/converting-from-shell-to-julia/41531 "2020-06-17T02:54:23Z")

</div>

Hello there geeks, New to Julia, I’m curious to see how much of my shell scripts I will be able to convert to Julia. I have this script that create user accounts with random passwords #!/bin/bash # This script automat…

---

## [Best Solver for Bessel-like Differential Equations with Singularity; unexpected Interpolation Behavior](https://discourse.julialang.org/t/best-solver-for-bessel-like-differential-equations-with-singularity-unexpected-interpolation-behavior/41482)

<div class="topic-metadata">

**Author:** [@CosmoProf](https://discourse.julialang.org/u/CosmoProf)\
**Replies:** 6\
**Last updated:** [June 17, 2020, 2:27am UTC](https://discourse.julialang.org/t/best-solver-for-bessel-like-differential-equations-with-singularity-unexpected-interpolation-behavior/41482 "2020-06-17T02:27:20Z")

</div>

Hi, I’m starting a project solving equations (using the DifferentialEquations.jl package) that will be similar to Bessel equations: oscillatory in general, with a singularity in the function and its derivatives at t=0. (…

---

## [Hi everybody](https://discourse.julialang.org/t/hi-everybody/41567)

<div class="topic-metadata">

**Author:** [@Crazyguy98](https://discourse.julialang.org/u/Crazyguy98)\
**Replies:** 2\
**Last updated:** [June 17, 2020, 2:06am UTC](https://discourse.julialang.org/t/hi-everybody/41567 "2020-06-17T02:06:41Z")

</div>

Hi everybody Pleased to meet you! First, let me introduce myself. I am Huynh I just joined this forum. I am very happy to get to know everyone. The forum has lots of useful news. I will read it every day. It was a ple…

---

## [Stack overflow error with @SDconstraint](https://discourse.julialang.org/t/stack-overflow-error-with-sdconstraint/41557)

<div class="topic-metadata">

**Author:** [@stephentu](https://discourse.julialang.org/u/stephentu)\
**Replies:** 3\
**Last updated:** [June 17, 2020, 12:59am UTC](https://discourse.julialang.org/t/stack-overflow-error-with-sdconstraint/41557 "2020-06-17T00:59:30Z")

</div>

I have the following simple code snippet which is causing me issues: function find\_common\_lyapunov(system::PiecewiseLinearSystem, gamma::Float64) @assert(gamma \> 0.0) dim = system\_dim(system) model = Model(M…

---

## [Multithreaded GC?](https://discourse.julialang.org/t/multithreaded-gc/41541)

<div class="topic-metadata">

**Author:** [@dlakelan](https://discourse.julialang.org/u/dlakelan)\
**Replies:** 18\
**Last updated:** [June 16, 2020, 11:39pm UTC](https://discourse.julialang.org/t/multithreaded-gc/41541 "2020-06-16T23:39:14Z")

</div>

I’ve seen several threads on garbage collection and its impact on low-latency / soft realtime usage. I was thinking about some raspberry pi type projects (I need to come up with things to do with my kids during COVID) an…

---

## [Nominate for the Julia Community Prize, 2020](https://discourse.julialang.org/t/nominate-for-the-julia-community-prize-2020/40263)

<div class="topic-metadata">

**Author:** [@avik](https://discourse.julialang.org/u/avik)\
**Replies:** 11\
**Last updated:** [June 16, 2020, 10:19pm UTC](https://discourse.julialang.org/t/nominate-for-the-julia-community-prize-2020/40263 "2020-06-16T22:19:18Z")

</div>

It’s time to nominate your favourite Julia contributor for the Julia Community Prize, 2020. The prize will be announced at JuliaCon 2020 in July. Contributions can be in any area - code, packages, documentation, applica…

---

## [Lightgraph + ModelToolkit optimization](https://discourse.julialang.org/t/lightgraph-modeltoolkit-optimization/40696)

<div class="topic-metadata">

**Author:** [@erlebach](https://discourse.julialang.org/u/erlebach)\
**Replies:** 61\
**Last updated:** [June 16, 2020, 10:08pm UTC](https://discourse.julialang.org/t/lightgraph-modeltoolkit-optimization/40696 "2020-06-16T22:08:49Z")

</div>

Hi, I finally got an SIR model to work with SIR combined with ModelToolkit. Here is the code: using Plots using DataFrames using ModelingToolkit using DiffEqBase using DiffEqJump using LightGraphs using SpecialGraphs …

---

## [Why selectdim is type instable](https://discourse.julialang.org/t/why-selectdim-is-type-instable/25271)

<div class="topic-metadata">

**Author:** [@shipengcheng1230](https://discourse.julialang.org/u/shipengcheng1230)\
**Replies:** 9\
**Last updated:** [June 16, 2020, 9:54pm UTC](https://discourse.julialang.org/t/why-selectdim-is-type-instable/25271 "2020-06-16T21:54:58Z")

</div>

Hi, I just found that selectdim does not infer the concrete SubArray: julia\> using InteractiveUtils julia\> a = rand(5, 5); julia\> @code\_warntype selectdim(a, 2, 1) Body::SubArray 1 ─ %1 = (Base.arraysize)(A, 1)::Int6…

---

## [Solving Differential Equations in "real time"](https://discourse.julialang.org/t/solving-differential-equations-in-real-time/41546)

<div class="topic-metadata">

**Author:** [@Ronis\_BR](https://discourse.julialang.org/u/Ronis_BR)\
**Replies:** 6\
**Last updated:** [June 16, 2020, 9:20pm UTC](https://discourse.julialang.org/t/solving-differential-equations-in-real-time/41546 "2020-06-16T21:20:10Z")

</div>

Hi! Is there a way to use Differential Equations to solve a system in “real time”? I want to solve a dynamic system that will receive data from the Raspberry Pi to update the simulation. Thus, this system must be solved…

---

## [Accelerated gradient descent algorithm](https://discourse.julialang.org/t/accelerated-gradient-descent-algorithm/41551)

<div class="topic-metadata">

**Author:** [@A.U.M](https://discourse.julialang.org/u/A.U.M)\
**Replies:** 1\
**Last updated:** [June 16, 2020, 8:59pm UTC](https://discourse.julialang.org/t/accelerated-gradient-descent-algorithm/41551 "2020-06-16T20:59:42Z")

</div>

Hello, I am searching for an Example of the accelerated gradient descent Algorithm written in Julia … any recommendation?

---

## [Mechanism for optional interface functions - is this a bad idea?](https://discourse.julialang.org/t/mechanism-for-optional-interface-functions-is-this-a-bad-idea/41466)

<div class="topic-metadata">

**Author:** [@zsunberg](https://discourse.julialang.org/u/zsunberg)\
**Replies:** 2\
**Last updated:** [June 16, 2020, 8:48pm UTC](https://discourse.julialang.org/t/mechanism-for-optional-interface-functions-is-this-a-bad-idea/41466 "2020-06-16T20:48:10Z")

</div>

Hi all, some of us are working on an interface for reinforcement learning https://github.com/JuliaReinforcementLearning/CommonRLInterface.jl. There will be many interface functions that are optional, and perhaps multiple…

---

## [Updating to MCMCChains v4.0.0 results in Turing downgrade](https://discourse.julialang.org/t/updating-to-mcmcchains-v4-0-0-results-in-turing-downgrade/41463)

<div class="topic-metadata">

**Author:** [@EricChameroy](https://discourse.julialang.org/u/EricChameroy)\
**Replies:** 9\
**Last updated:** [June 16, 2020, 7:23pm UTC](https://discourse.julialang.org/t/updating-to-mcmcchains-v4-0-0-results-in-turing-downgrade/41463 "2020-06-16T19:23:19Z")

</div>

Upgrading to the latest MCMChains results in Turing downgrading from v0.13.0 to v0.7.1. Has anyone else had this issue? Is there a workaround? In the meantime, I’ve pinned Turing to prevent the downgrade. Should I repor…

---

## [Failure to calculate the gradient of ODE with the RHS as an argument: "LoadError: TypeError: in TrackedReal, in V, expected V\<:Real, got Type{Any}"](https://discourse.julialang.org/t/failure-to-calculate-the-gradient-of-ode-with-the-rhs-as-an-argument-loaderror-typeerror-in-trackedreal-in-v-expected-v-real-got-type-any/41480)

<div class="topic-metadata">

**Author:** [@yanz4](https://discourse.julialang.org/u/yanz4)\
**Replies:** 4\
**Last updated:** [June 16, 2020, 6:16pm UTC](https://discourse.julialang.org/t/failure-to-calculate-the-gradient-of-ode-with-the-rhs-as-an-argument-loaderror-typeerror-in-trackedreal-in-v-expected-v-real-got-type-any/41480 "2020-06-16T18:16:55Z")

</div>

Dear Forum, I am trying to add ODE into machine learning pipeline and calculate the gradient of an ode layer that takes the RHS as an argument. We tried to feed the RHS, in terms of inputFunction(t), into ODE (i.e. fiip…

---

## [How to use the summation in Julia?](https://discourse.julialang.org/t/how-to-use-the-summation-in-julia/41522)

<div class="topic-metadata">

**Author:** [@RaquelSantos](https://discourse.julialang.org/u/RaquelSantos)\
**Replies:** 5\
**Last updated:** [June 16, 2020, 6:07pm UTC](https://discourse.julialang.org/t/how-to-use-the-summation-in-julia/41522 "2020-06-16T18:07:52Z")

</div>

I need to put this objective function in Julia, but I don’t know how to build a sum that has 3 indexes. Can someone help me? I started doing like this using JuMP, Cbc Model1 = Model(with\_optimizer(Cbc.Optimizer)) CR …

---

## [What's wrong with the 'while' line which is "missing comma or )"?](https://discourse.julialang.org/t/whats-wrong-with-the-while-line-which-is-missing-comma-or/41537)

<div class="topic-metadata">

**Author:** [@reb](https://discourse.julialang.org/u/reb)\
**Replies:** 1\
**Last updated:** [June 16, 2020, 5:46pm UTC](https://discourse.julialang.org/t/whats-wrong-with-the-while-line-which-is-missing-comma-or/41537 "2020-06-16T17:46:19Z")

</div>

arr = \[“6”,“-”,“2”," “,“6=”,”-“,“3”\] lenarr = 7 println(“arr=”,arr,” lenarr=",lenarr) i = 1 while (((arr\[i\] == " ") or (arr\[i\] == “\\t”)) and (i \< lenarr)) i = i + 1 end firstindex = i

---

## [Playing with function composition, is there a name for what I'm doing?](https://discourse.julialang.org/t/playing-with-function-composition-is-there-a-name-for-what-im-doing/41533)

<div class="topic-metadata">

**Author:** [@klaff](https://discourse.julialang.org/u/klaff)\
**Replies:** 2\
**Last updated:** [June 16, 2020, 5:06pm UTC](https://discourse.julialang.org/t/playing-with-function-composition-is-there-a-name-for-what-im-doing/41533 "2020-06-16T17:06:34Z")

</div>

For AC analysis of circuits the following is handy: using Plots ZL(L) = f -\> im\*2π\*f\*L ZC(C) = f -\> 1/(im\*2π\*f\*C) ZR(R) = f -\> R series(a,b,c...) = f -\> sum(\[x(f) for x in \[\[a,b\]; \[c...\]\]\]) parallel(a,b,c...) = f -\> 1/…

---

## [Plan: when julia base will start to use threads?](https://discourse.julialang.org/t/plan-when-julia-base-will-start-to-use-threads/41507)

<div class="topic-metadata">

**Author:** [@stakaz](https://discourse.julialang.org/u/stakaz)\
**Replies:** 1\
**Last updated:** [June 16, 2020, 4:46pm UTC](https://discourse.julialang.org/t/plan-when-julia-base-will-start-to-use-threads/41507 "2020-06-16T16:46:06Z")

</div>

Hello, I just wonder, if there is a time plan for julia base to use threads to parallelized the computations by default? Right now as I can see, only user defined threads actually can speed up things but not the base-co…

---

## [How to easily rename column of GroupedDataFrame](https://discourse.julialang.org/t/how-to-easily-rename-column-of-groupeddataframe/41505)

<div class="topic-metadata">

**Author:** [@SSU](https://discourse.julialang.org/u/SSU)\
**Replies:** 2\
**Last updated:** [June 16, 2020, 1:58pm UTC](https://discourse.julialang.org/t/how-to-easily-rename-column-of-groupeddataframe/41505 "2020-06-16T13:58:49Z")

</div>

Hi! I want to know how to rename the column of GroupedDataFrame easily. The following code is an example of what I want to do. Note: the real data I want to handle is a huge dataframe(~ 10 millions of rows). Any sugg…

---

## [The usage of \`QMDP\`](https://discourse.julialang.org/t/the-usage-of-qmdp/41518)

<div class="topic-metadata">

**Author:** [@jkwwwwow](https://discourse.julialang.org/u/jkwwwwow)\
**Replies:** 0\
**Last updated:** [June 16, 2020, 1:25pm UTC](https://discourse.julialang.org/t/the-usage-of-qmdp/41518 "2020-06-16T13:25:01Z")

</div>

Hello everyone, I’m not particularly sure if I posted this content in the appropriate section. I am trying to run a program on Github (https://github.com/mexsser/POMDPIDMModel.jl), but when I finish the installation par…

---

## [Error building \`GR\`](https://discourse.julialang.org/t/error-building-gr/41489)

<div class="topic-metadata">

**Author:** [@jkwwwwow](https://discourse.julialang.org/u/jkwwwwow)\
**Replies:** 3\
**Last updated:** [June 16, 2020, 12:29pm UTC](https://discourse.julialang.org/t/error-building-gr/41489 "2020-06-16T12:29:51Z")

</div>

I met a building error when I tried to add a package in here: Error: Error building \`GR\`: │ │ gzip: stdin: unexpected end of file │ tar: 归档文件中异常的 EOF │ tar: 归档文件中异常的 EOF │ tar: Error is not recoverable: exiting now │ …

---

## [Problem Lambdifying atan function](https://discourse.julialang.org/t/problem-lambdifying-atan-function/41501)

<div class="topic-metadata">

**Author:** [@Jake\_Double\_U](https://discourse.julialang.org/u/Jake_Double_U)\
**Replies:** 3\
**Last updated:** [June 16, 2020, 12:20pm UTC](https://discourse.julialang.org/t/problem-lambdifying-atan-function/41501 "2020-06-16T12:20:46Z")

</div>

Hi Folks, Apology if this is not the appropriate location for this post. Also, I am not much of a computer programmer so I also apologize for any incorrect terminology in the following. I have run across a problem tha…

---

## [TensorCast & CUDA](https://discourse.julialang.org/t/tensorcast-cuda/41483)

<div class="topic-metadata">

**Author:** [@bryce](https://discourse.julialang.org/u/bryce)\
**Replies:** 2\
**Last updated:** [June 16, 2020, 12:16pm UTC](https://discourse.julialang.org/t/tensorcast-cuda/41483 "2020-06-16T12:16:35Z")

</div>

I’m having problems using TensorCast on CuArrays. When I run the following with normal arrays, it works fine: using TensorCast C = ones(10,2) L = ones(10,3) @reduce D\[m,a\] := sum(p) C\[p,a\] + L\[p,m\] 3×2 Array{Float64,2}…

---

## [Distributed computing, not found package error](https://discourse.julialang.org/t/distributed-computing-not-found-package-error/34851)

<div class="topic-metadata">

**Author:** [@rbontekoe](https://discourse.julialang.org/u/rbontekoe)\
**Replies:** 7\
**Last updated:** [June 16, 2020, 12:08pm UTC](https://discourse.julialang.org/t/distributed-computing-not-found-package-error/34851 "2020-06-16T12:08:46Z")

</div>

Hello, I need some help. I am using Julia 1.3.1 on Ubuntu 18.4. My code doesn’t run on a worker. What am I doing wrong? I created a Julia module AppliSales.jl: (AppliMaster) pkg\> add https://github.com/rbontekoe/AppliSa…

---

## [Compatibility problem when installing julia packages](https://discourse.julialang.org/t/compatibility-problem-when-installing-julia-packages/41423)

<div class="topic-metadata">

**Author:** [@jkwwwwow](https://discourse.julialang.org/u/jkwwwwow)\
**Replies:** 5\
**Last updated:** [June 16, 2020, 11:53am UTC](https://discourse.julialang.org/t/compatibility-problem-when-installing-julia-packages/41423 "2020-06-16T11:53:10Z")

</div>

I’m trying to run a Julia program (here), and I get the following error message: julia\> using Pkg julia\> Pkg.add(PackageSpec(url = "https://github.com/mexsser/POMDPIDMModel.jl")) Updating git-repo \`https://github.c…

---

## [Front ends for Julia codebases?](https://discourse.julialang.org/t/front-ends-for-julia-codebases/31370)

<div class="topic-metadata">

**Author:** [@anon92994695](https://discourse.julialang.org/u/anon92994695)\
**Replies:** 72\
**Last updated:** [June 16, 2020, 10:48am UTC](https://discourse.julialang.org/t/front-ends-for-julia-codebases/31370 "2020-06-16T10:48:15Z")

</div>

I have an idea. It involves a pretty UI with low latency. Unfortunately, I lack a bit of soft-ware skills. I know JAVA, a bit of scala, C#, bit of C/C++, yadda yadda. I’m most comfy in JAVA because development is easy, a…

---

## [Initialise a dict in a mutually circular type](https://discourse.julialang.org/t/initialise-a-dict-in-a-mutually-circular-type/41476)

<div class="topic-metadata">

**Author:** [@nacnudus](https://discourse.julialang.org/u/nacnudus)\
**Replies:** 5\
**Last updated:** [June 16, 2020, 5:40am UTC](https://discourse.julialang.org/t/initialise-a-dict-in-a-mutually-circular-type/41476 "2020-06-16T05:40:52Z")

</div>

I need to define two mutually circular types. I have read this issue, which suggests using a forward declaration. That works. However, I also need to contain the types in Dicts, which must be initialised. abstract ty…

---

## [Can I draw dot lines with GraphRecipes.jl?](https://discourse.julialang.org/t/can-i-draw-dot-lines-with-graphrecipes-jl/41495)

<div class="topic-metadata">

**Author:** [@larrylan](https://discourse.julialang.org/u/larrylan)\
**Replies:** 0\
**Last updated:** [June 16, 2020, 4:17am UTC](https://discourse.julialang.org/t/can-i-draw-dot-lines-with-graphrecipes-jl/41495 "2020-06-16T04:17:06Z")

</div>

Greetings, I’m trying to use GraphRecipes to draw networks because I can spot nodes with their specific coordinates with GraphRecipes, e.g. this simple example GitHub - JuliaPlots/GraphRecipes.jl: Graph-related recipes …

---

## [Anyway to increase the heatmap "block" height?](https://discourse.julialang.org/t/anyway-to-increase-the-heatmap-block-height/41355)

<div class="topic-metadata">

**Author:** [@affans](https://discourse.julialang.org/u/affans)\
**Replies:** 2\
**Last updated:** [June 16, 2020, 12:05am UTC](https://discourse.julialang.org/t/anyway-to-increase-the-heatmap-block-height/41355 "2020-06-16T00:05:09Z")

</div>

I am constructing a heatmap heatmap(xvals, yvals, zvals, size=(500,2000) but because the yvals are texts, they seem to overlap and jumble together. See Now increase size=(500, 10000) helps only slightly and seems to…

---

## [Pkg.develop() causing package to downgrade](https://discourse.julialang.org/t/pkg-develop-causing-package-to-downgrade/41484)

<div class="topic-metadata">

**Author:** [@EmadMasroor](https://discourse.julialang.org/u/EmadMasroor)\
**Replies:** 0\
**Last updated:** [June 15, 2020, 11:46pm UTC](https://discourse.julialang.org/t/pkg-develop-causing-package-to-downgrade/41484 "2020-06-15T23:46:28Z")

</div>

I am having trouble using pkg\> develop on a registered Julia package. Here’s the situation: When I enter Pkg mode on the REPL and add ViscousFlow, the correct package at the most recent version gets downloaded from the g…

---

## [Access jth component of stacked 1D array](https://discourse.julialang.org/t/access-jth-component-of-stacked-1d-array/41461)

<div class="topic-metadata">

**Author:** [@mleprovost](https://discourse.julialang.org/u/mleprovost)\
**Replies:** 6\
**Last updated:** [June 15, 2020, 11:07pm UTC](https://discourse.julialang.org/t/access-jth-component-of-stacked-1d-array/41461 "2020-06-15T23:07:04Z")

</div>

Hello, I would like to access the jth component of stacked 1D arrays, what is the best option? Is it possible to create a view of this subarray? e.g.: Nx = 50 Ne = 20 A = map(i-\>randn(Nx,1:Ne) # Access jth component…

[Previous page](https://discourse.julialang.org/latest.md?page=1714)

[Next page](https://discourse.julialang.org/latest.md?page=1716)