# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1594

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

**Page:** 1595

---

## [A blog post involving Julia](https://discourse.julialang.org/t/a-blog-post-involving-julia/48809)

<div class="topic-metadata">

**Author:** [@stla](https://discourse.julialang.org/u/stla)\
**Replies:** 15\
**Last updated:** [October 23, 2020, 9:25am UTC](https://discourse.julialang.org/t/a-blog-post-involving-julia/48809 "2020-10-23T09:25:39Z")

</div>

Hello, I’ve just blogged a post involving Julia. It compares the speed of the same algorithm in C++, Haskell, and Julia. Haskell won vs Julia 1.2.0, but now it is beaten by Julia 1.5.2. Cheers.

---

## [Calculation time of Runge Kutta method](https://discourse.julialang.org/t/calculation-time-of-runge-kutta-method/48869)

<div class="topic-metadata">

**Author:** [@yosuga](https://discourse.julialang.org/u/yosuga)\
**Replies:** 1\
**Last updated:** [October 23, 2020, 8:28am UTC](https://discourse.julialang.org/t/calculation-time-of-runge-kutta-method/48869 "2020-10-23T08:28:35Z")

</div>

I’m trying to calculate a matrix-form ODE, i.e., (∂/∂t)ψ = -iHψ ,where ψ is a vector and H is a (time-independent) matrix. I have two problems. 1. Difference of calculation time between DifferentialEquations.jl and Ru…

---

## [Find packages by function names](https://discourse.julialang.org/t/find-packages-by-function-names/48823)

<div class="topic-metadata">

**Author:** [@rdemaria](https://discourse.julialang.org/u/rdemaria)\
**Replies:** 5\
**Last updated:** [October 23, 2020, 7:40am UTC](https://discourse.julialang.org/t/find-packages-by-function-names/48823 "2020-10-23T07:40:07Z")

</div>

I am taking my first steps with Julia (using version 1.5), I found a nice package and tried to run an example, which was making use of “norm” and “info”. These functions are not in the default scope, but probably they …

---

## [Using views slows down my code](https://discourse.julialang.org/t/using-views-slows-down-my-code/48863)

<div class="topic-metadata">

**Author:** [@ash](https://discourse.julialang.org/u/ash)\
**Replies:** 5\
**Last updated:** [October 23, 2020, 7:32am UTC](https://discourse.julialang.org/t/using-views-slows-down-my-code/48863 "2020-10-23T07:32:16Z")

</div>

Several people on the discourse have recently suggested I use views to improve my code’s performance. However, for some reason, it actually slows down my code when I use them. To test this, I wrote the following MWE: us…

---

## [Flux with Julia master fails with IRCode error](https://discourse.julialang.org/t/flux-with-julia-master-fails-with-ircode-error/48865)

<div class="topic-metadata">

**Author:** [@Colin\_Beckingham](https://discourse.julialang.org/u/Colin_Beckingham)\
**Replies:** 0\
**Last updated:** [October 23, 2020, 6:14am UTC](https://discourse.julialang.org/t/flux-with-julia-master-fails-with-ircode-error/48865 "2020-10-23T06:14:57Z")

</div>

Using the sample code from the documentation for Flux Optimizers, with Julia 1.5.2 the code works (apart from a warning about slow compilation) but fails with master on julia\> grads = gradient(() -\> loss(x, y), θ) ERROR…

---

## [Using \`DataType\` as key in \`Dict\`](https://discourse.julialang.org/t/using-datatype-as-key-in-dict/48796)

<div class="topic-metadata">

**Author:** [@colintbowers](https://discourse.julialang.org/u/colintbowers)\
**Replies:** 10\
**Last updated:** [October 23, 2020, 5:53am UTC](https://discourse.julialang.org/t/using-datatype-as-key-in-dict/48796 "2020-10-23T05:53:40Z")

</div>

Hi all, Just a quick question: Is it a bad idea to use DataType as the key in a Dict if performance is reasonably important? So, something like this: struct MyType ; end d = Dict(Float64=\>"a", MyType=\>"b") Using Bench…

---

## [Unsatisfiable requirements detected for package DifferentialEquations](https://discourse.julialang.org/t/unsatisfiable-requirements-detected-for-package-differentialequations/48860)

<div class="topic-metadata">

**Author:** [@HerAdri](https://discourse.julialang.org/u/HerAdri)\
**Replies:** 1\
**Last updated:** [October 23, 2020, 5:20am UTC](https://discourse.julialang.org/t/unsatisfiable-requirements-detected-for-package-differentialequations/48860 "2020-10-23T05:20:26Z")

</div>

pkg\> update ERROR: Unsatisfiable requirements detected for package DifferentialEquations \[0c46a032\]: DifferentialEquations \[0c46a032\] log: ├─DifferentialEquations \[0c46a032\] has no known versions! └─restricted to vers…

---

## [Passing \`limits\` as function arguments](https://discourse.julialang.org/t/passing-limits-as-function-arguments/13777)

<div class="topic-metadata">

**Author:** [@hasanOryx](https://discourse.julialang.org/u/hasanOryx)\
**Replies:** 15\
**Last updated:** [October 23, 2020, 4:39am UTC](https://discourse.julialang.org/t/passing-limits-as-function-arguments/13777 "2020-10-23T04:39:40Z")

</div>

I’m tryin to build a function that take 2 inputs limits and Function, so I wrote the below: function Σ(limits, f::Function) @show limits @show f end Σ((i=1:3), :(x-\>x^2)) But it could not run, with the below e…

---

## [Function searchindex not defined?](https://discourse.julialang.org/t/function-searchindex-not-defined/48854)

<div class="topic-metadata">

**Author:** [@KW2P](https://discourse.julialang.org/u/KW2P)\
**Replies:** 2\
**Last updated:** [October 23, 2020, 4:04am UTC](https://discourse.julialang.org/t/function-searchindex-not-defined/48854 "2020-10-23T04:04:42Z")

</div>

This has to be something dumb but I’m not seeing it. I get this error: ERROR: LoadError: UndefVarError: searchindex not defined Stacktrace: \[1\] readConfigFile() at /home/phil/dev/jdev/utils.jl:114 \[2\] top-level scope…

---

## [Which symbols are special cased in the same way as \`.\*\`, \`.+\`, etc](https://discourse.julialang.org/t/which-symbols-are-special-cased-in-the-same-way-as-etc/48849)

<div class="topic-metadata">

**Author:** [@pdeffebach](https://discourse.julialang.org/u/pdeffebach)\
**Replies:** 5\
**Last updated:** [October 22, 2020, 10:15pm UTC](https://discourse.julialang.org/t/which-symbols-are-special-cased-in-the-same-way-as-etc/48849 "2020-10-22T22:15:33Z")

</div>

I am working on something in DataFramesMeta where I take an expression z = :x + :y if, like the expression above, the RHS is of the form +(:x, :y), then I can use DataFrames to create the object \[:x, :y\] =\> (+) =\> :y…

---

## [Numerical error when optimising expression with JuMP](https://discourse.julialang.org/t/numerical-error-when-optimising-expression-with-jump/48847)

<div class="topic-metadata">

**Author:** [@f6v](https://discourse.julialang.org/u/f6v)\
**Replies:** 1\
**Last updated:** [October 22, 2020, 9:58pm UTC](https://discourse.julialang.org/t/numerical-error-when-optimising-expression-with-jump/48847 "2020-10-22T21:58:40Z")

</div>

I’m completely new to mathematical optimisation and would appreciate if you could give a hint here. I have a function of three vectors x, y and z(each of size 15). Now I want to maximise a function of the vectors with c…

---

## [Computing the rank of a symbolic matrix in Julia](https://discourse.julialang.org/t/computing-the-rank-of-a-symbolic-matrix-in-julia/48651)

<div class="topic-metadata">

**Author:** [@AS90](https://discourse.julialang.org/u/AS90)\
**Replies:** 25\
**Last updated:** [October 22, 2020, 8:58pm UTC](https://discourse.julialang.org/t/computing-the-rank-of-a-symbolic-matrix-in-julia/48651 "2020-10-22T20:58:05Z")

</div>

Hello. The context is that of discrete state space representations. x\_{t}=Ax\_{t-1}+Bu\_{t} y\_{t}=Cx\_{t-1}+Du\_{t} I am making observational assumptions on the rows of x\_{t} and I need to work symbolically. Specifically,…

---

## [Are there idioms in Julia for fast Algebraic Data Types (ADT)?](https://discourse.julialang.org/t/are-there-idioms-in-julia-for-fast-algebraic-data-types-adt/37244)

<div class="topic-metadata">

**Author:** [@jonathan-laurent](https://discourse.julialang.org/u/jonathan-laurent)\
**Replies:** 41\
**Last updated:** [October 22, 2020, 8:11pm UTC](https://discourse.julialang.org/t/are-there-idioms-in-julia-for-fast-algebraic-data-types-adt/37244 "2020-10-22T20:11:51Z")

</div>

Coming from functional programming, one of the features I have been missing the most in Julia are Algebraic Data Types. Packages such as MLStyle are doing a pretty good job at adding them into the language but I am more …

---

## [Display of =\> using JuliaMono](https://discourse.julialang.org/t/display-of-using-juliamono/48619)

<div class="topic-metadata">

**Author:** [@jishnub](https://discourse.julialang.org/u/jishnub)\
**Replies:** 3\
**Last updated:** [October 22, 2020, 7:53pm UTC](https://discourse.julialang.org/t/display-of-using-juliamono/48619 "2020-10-22T19:53:17Z")

</div>

I’ve been facing a somewhat strange issue using the JuliaMono font, where the Dict map character =\> displays differently depending on the type of the key. I am using Sublime text as my editor, wondering if anyone else…

---

## [Warning on Plots in Jupyter](https://discourse.julialang.org/t/warning-on-plots-in-jupyter/48836)

<div class="topic-metadata">

**Author:** [@gideonsimpson](https://discourse.julialang.org/u/gideonsimpson)\
**Replies:** 3\
**Last updated:** [October 22, 2020, 7:18pm UTC](https://discourse.julialang.org/t/warning-on-plots-in-jupyter/48836 "2020-10-22T19:18:34Z")

</div>

Not sure if this merits a bug report, but I recently started having the following warning pop up. It doesn’t seem to interfere with my ability to generate figures, and it does not show up in the REPL: │ MethodError: no…

---

## [\[ANN\] Interpolations.jl v0.13.x](https://discourse.julialang.org/t/ann-interpolations-jl-v0-13-x/48607)

<div class="topic-metadata">

**Author:** [@mkitti](https://discourse.julialang.org/u/mkitti)\
**Replies:** 6\
**Last updated:** [October 22, 2020, 6:08pm UTC](https://discourse.julialang.org/t/ann-interpolations-jl-v0-13-x/48607 "2020-10-22T18:08:45Z")

</div>

Hello all, I would like to announce the registration of Interpolations.jl v0.13.0. This marks my first release as the new maintainer for Interpolations.jl after @tim.holy stepped down as maintainer. The new release i…

---

## [Parrallel programming with Distributed Arrays](https://discourse.julialang.org/t/parrallel-programming-with-distributed-arrays/48794)

<div class="topic-metadata">

**Author:** [@hyacykcharel](https://discourse.julialang.org/u/hyacykcharel)\
**Replies:** 5\
**Last updated:** [October 22, 2020, 6:01pm UTC](https://discourse.julialang.org/t/parrallel-programming-with-distributed-arrays/48794 "2020-10-22T18:01:41Z")

</div>

please I need help, I'm trying to do this equation in parallel but it is not working can someone tell what's wrong? thanks #Heat Equation #Numerical Solution using Distributed addprocs(4) @everywhere using LinearAlgebra…

---

## [Dot notation](https://discourse.julialang.org/t/dot-notation/48776)

<div class="topic-metadata">

**Author:** [@rcnlee](https://discourse.julialang.org/u/rcnlee)\
**Replies:** 5\
**Last updated:** [October 22, 2020, 4:38pm UTC](https://discourse.julialang.org/t/dot-notation/48776 "2020-10-22T16:38:32Z")

</div>

Hello, I’m trying to understand the internals of what happens when using the dot notation. There seems to be a few ways to make the call: x = \[1,2,3\]; y=\[0,2,4\] x .\<= y #method 1 .\<=(x,y) #method 2 (\<=).(x,y) #method …

---

## [Is it possible to use variables in Pluto sliders?](https://discourse.julialang.org/t/is-it-possible-to-use-variables-in-pluto-sliders/48828)

<div class="topic-metadata">

**Author:** [@mihalybaci](https://discourse.julialang.org/u/mihalybaci)\
**Replies:** 2\
**Last updated:** [October 22, 2020, 4:21pm UTC](https://discourse.julialang.org/t/is-it-possible-to-use-variables-in-pluto-sliders/48828 "2020-10-22T16:21:52Z")

</div>

So far I am loving the interactivity in Pluto notebooks, but I am frequently hitting a roadblock in setting up sliders. I find I have to manually set the slider range like this begin number\_slider = @bind number html"\<i…

---

## [Load a dependency only when calling a method that needs it](https://discourse.julialang.org/t/load-a-dependency-only-when-calling-a-method-that-needs-it/48804)

<div class="topic-metadata">

**Author:** [@pablosanjose](https://discourse.julialang.org/u/pablosanjose)\
**Replies:** 6\
**Last updated:** [October 22, 2020, 3:04pm UTC](https://discourse.julialang.org/t/load-a-dependency-only-when-calling-a-method-that-needs-it/48804 "2020-10-22T15:04:21Z")

</div>

I’m building a package for which I want to minimize using load time. It has a bunch of dependencies that are only needed for some specific functionalities, called via specific methods. Can I somehow delay loading the dep…

---

## [No collect!() function?](https://discourse.julialang.org/t/no-collect-function/48815)

<div class="topic-metadata">

**Author:** [@tomtom](https://discourse.julialang.org/u/tomtom)\
**Replies:** 6\
**Last updated:** [October 22, 2020, 2:29pm UTC](https://discourse.julialang.org/t/no-collect-function/48815 "2020-10-22T14:29:30Z")

</div>

seems like an implementation of collect!() is missing? how could I do in-place collection like collect!(v, range(1, 10, length=3)) then? Thanks.

---

## [Custom versus Package function names](https://discourse.julialang.org/t/custom-versus-package-function-names/48711)

<div class="topic-metadata">

**Author:** [@dalarev](https://discourse.julialang.org/u/dalarev)\
**Replies:** 9\
**Last updated:** [October 22, 2020, 2:26pm UTC](https://discourse.julialang.org/t/custom-versus-package-function-names/48711 "2020-10-22T14:26:28Z")

</div>

I think I am having issues with my custom function grid conflicting with the Plots package grid . How can I specify (is “qualify” the better term?) that I want to use my own? To specify Plots’ version, I would do Plots.…

---

## [How to debug dead IJulia kernels (julia 1.4.1)](https://discourse.julialang.org/t/how-to-debug-dead-ijulia-kernels-julia-1-4-1/39063)

<div class="topic-metadata">

**Author:** [@Alexander-Barth](https://discourse.julialang.org/u/Alexander-Barth)\
**Replies:** 2\
**Last updated:** [October 22, 2020, 1:59pm UTC](https://discourse.julialang.org/t/how-to-debug-dead-ijulia-kernels-julia-1-4-1/39063 "2020-10-22T13:59:00Z")

</div>

I am trying to help two students whom I asked to install julia 1.4.1 and IJulia (one on Windows, and one on Kubuntu 20.04). Both have the issue that the IJulia kernel is crashing directly. Here is a thread of the discus…

---

## [Substituting Expression for Symbol in Nested Expression](https://discourse.julialang.org/t/substituting-expression-for-symbol-in-nested-expression/36366)

<div class="topic-metadata">

**Author:** [@r-b0](https://discourse.julialang.org/u/r-b0)\
**Replies:** 5\
**Last updated:** [October 22, 2020, 12:55pm UTC](https://discourse.julialang.org/t/substituting-expression-for-symbol-in-nested-expression/36366 "2020-10-22T12:55:54Z")

</div>

Let’s suppose I have a situation which necessitates substituting an expression for a symbol in a nested expression. Let’s further suppose that I am unable to acomplish this by acting on the string before parsing using s…

---

## [How to run julia code remotely on another local machine?](https://discourse.julialang.org/t/how-to-run-julia-code-remotely-on-another-local-machine/48765)

<div class="topic-metadata">

**Author:** [@StatisticalMouse](https://discourse.julialang.org/u/StatisticalMouse)\
**Replies:** 12\
**Last updated:** [October 22, 2020, 12:33pm UTC](https://discourse.julialang.org/t/how-to-run-julia-code-remotely-on-another-local-machine/48765 "2020-10-22T12:33:43Z")

</div>

My main machine is a MacBook Pro, where I edit Julia. I also have a PC running Windows that has an 8-core CPU and a GTX-1070ti. I can connect them via local LAN. Is there some good way that I could send Julia that I e…

---

## [Exponential matrix calculation with the exp() function vs procedure with the use of the eigen() function](https://discourse.julialang.org/t/exponential-matrix-calculation-with-the-exp-function-vs-procedure-with-the-use-of-the-eigen-function/48798)

<div class="topic-metadata">

**Author:** [@HerAdri](https://discourse.julialang.org/u/HerAdri)\
**Replies:** 7\
**Last updated:** [October 22, 2020, 12:11pm UTC](https://discourse.julialang.org/t/exponential-matrix-calculation-with-the-exp-function-vs-procedure-with-the-use-of-the-eigen-function/48798 "2020-10-22T12:11:02Z")

</div>

Using the procedure shown in Matrix Exponentiation , I have performed the calculation of the exponential matrix: for the case of the first matrix, the result of the procedure matches the result returned by the function …

---

## [How to convert UniformScaling with single entry to Number?](https://discourse.julialang.org/t/how-to-convert-uniformscaling-with-single-entry-to-number/48751)

<div class="topic-metadata">

**Author:** [@juliohm](https://discourse.julialang.org/u/juliohm)\
**Replies:** 8\
**Last updated:** [October 22, 2020, 11:56am UTC](https://discourse.julialang.org/t/how-to-convert-uniformscaling-with-single-entry-to-number/48751 "2020-10-22T11:56:20Z")

</div>

Copying a question from Zulip given that it may be useful in general to discuss in Discourse… A good trick to perform algebraic operations with both arrays and numbers generically is to use LinearAlgebra.I instead of 1: …

---

## [Techniques to improve resolution of a system of nonlinear equations](https://discourse.julialang.org/t/techniques-to-improve-resolution-of-a-system-of-nonlinear-equations/48712)

<div class="topic-metadata">

**Author:** [@mleprovost](https://discourse.julialang.org/u/mleprovost)\
**Replies:** 13\
**Last updated:** [October 22, 2020, 10:28am UTC](https://discourse.julialang.org/t/techniques-to-improve-resolution-of-a-system-of-nonlinear-equations/48712 "2020-10-22T10:28:36Z")

</div>

Hello, I would like to solve a set of N = 300 independent 1D nonlinear equations of the type f\_i(x\_i) = a\_i where the a\_i are given and each function f\_i is a univariate strictly increasing bijection. There is a unique…

---

## [Couenne with JuMP: can't evaluate pow"(0,1.5)](https://discourse.julialang.org/t/couenne-with-jump-cant-evaluate-pow-0-1-5/48734)

<div class="topic-metadata">

**Author:** [@Shuhua](https://discourse.julialang.org/u/Shuhua)\
**Replies:** 3\
**Last updated:** [October 22, 2020, 9:15am UTC](https://discourse.julialang.org/t/couenne-with-jump-cant-evaluate-pow-0-1-5/48734 "2020-10-22T09:15:52Z")

</div>

I am playing with Couenne for NLP optimization problems with JuMP and AmplNLWriter. After setting up these packages, I tried the toy example in Couenne’s documentation (section 5). For convenience, the problem is posted …

---

## [Using Gtk can I make a dialog pop up where I enter some text?](https://discourse.julialang.org/t/using-gtk-can-i-make-a-dialog-pop-up-where-i-enter-some-text/48774)

<div class="topic-metadata">

**Author:** [@Ahmed\_Salih](https://discourse.julialang.org/u/Ahmed_Salih)\
**Replies:** 4\
**Last updated:** [October 22, 2020, 8:30am UTC](https://discourse.julialang.org/t/using-gtk-can-i-make-a-dialog-pop-up-where-i-enter-some-text/48774 "2020-10-22T08:30:22Z")

</div>

Hi! Basically I want a small GUI to open up where it is just possible to write a line and then save that string. Is that possible? This is how far I am right now: ## Make small interface win = GtkWindow("Save File",30…

[Previous page](https://discourse.julialang.org/latest.md?page=1593)

[Next page](https://discourse.julialang.org/latest.md?page=1595)