# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1334

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

**Page:** 1335

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## [ModelingToolkit matrix form system of equations and complex values](https://discourse.julialang.org/t/modelingtoolkit-matrix-form-system-of-equations-and-complex-values/64431)

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**Author:** [@ograsdijk](https://discourse.julialang.org/u/ograsdijk)\
**Replies:** 5\
**Last updated:** [July 10, 2021, 9:55pm UTC](https://discourse.julialang.org/t/modelingtoolkit-matrix-form-system-of-equations-and-complex-values/64431 "2021-07-10T21:55:56Z")

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I’ve started looking into ModelingToolkit and I wanted to solve optical bloch differential equations with it, which have a complex part. I’ll preface this by saying I don’t have much experience with Julia yet, I started…

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## [Error when calculating RHS of reaction ode "no method matching Float64(::Num)"](https://discourse.julialang.org/t/error-when-calculating-rhs-of-reaction-ode-no-method-matching-float64-num/64420)

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**Author:** [@SA8416](https://discourse.julialang.org/u/SA8416)\
**Replies:** 4\
**Last updated:** [July 10, 2021, 8:59pm UTC](https://discourse.julialang.org/t/error-when-calculating-rhs-of-reaction-ode-no-method-matching-float64-num/64420 "2021-07-10T20:59:44Z")

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I have some code that uses a function to calculate some changes in concentration, but I get an error of: ERROR: LoadError: MethodError: no method matching Float64(::Num) Closest candidates are: (::Type{T})(::Real, ::R…

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## [Is there a unitful benchmark tool?](https://discourse.julialang.org/t/is-there-a-unitful-benchmark-tool/64436)

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**Author:** [@jzr](https://discourse.julialang.org/u/jzr)\
**Replies:** 0\
**Last updated:** [July 10, 2021, 7:35pm UTC](https://discourse.julialang.org/t/is-there-a-unitful-benchmark-tool/64436 "2021-07-10T19:35:11Z")

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It would be nice to have units on all my benchmarks. Does something like that exist? https://painterqubits.github.io/Unitful.jl/stable/

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## [DiffEqFlux “boundary” value problem](https://discourse.julialang.org/t/diffeqflux-boundary-value-problem/64110)

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**Author:** [@clm](https://discourse.julialang.org/u/clm)\
**Replies:** 3\
**Last updated:** [July 10, 2021, 7:12pm UTC](https://discourse.julialang.org/t/diffeqflux-boundary-value-problem/64110 "2021-07-10T19:12:22Z")

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After reading through a handful of DiffEqFlux examples, I’m really interested in how I might be able to apply it to a research question of mine measuring wind and temperature over glaciers. I have to solve this as a boun…

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## [Documenter.jl deployment issue with repo containing protocol](https://discourse.julialang.org/t/documenter-jl-deployment-issue-with-repo-containing-protocol/64367)

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**Author:** [@jeremiedb](https://discourse.julialang.org/u/jeremiedb)\
**Replies:** 1\
**Last updated:** [July 10, 2021, 6:45pm UTC](https://discourse.julialang.org/t/documenter-jl-deployment-issue-with-repo-containing-protocol/64367 "2021-07-10T18:45:04Z")

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Attempt to deploy docs using Documenter.jl fails following merge into master with the following error: ┌ Info: Deployment criteria for deploying devbranch build from GitHub Actions: │ - ✔ ENV\["GITHUB\_REPOSITORY"\]="Evove…

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## [\[ACCEPTED\] BoF for Live Coding & Beyond! Please Give Feedback!](https://discourse.julialang.org/t/accepted-bof-for-live-coding-beyond-please-give-feedback/62313)

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**Author:** [@TheCedarPrince](https://discourse.julialang.org/u/TheCedarPrince)\
**Replies:** 3\
**Last updated:** [July 10, 2021, 5:55pm UTC](https://discourse.julialang.org/t/accepted-bof-for-live-coding-beyond-please-give-feedback/62313 "2021-07-10T17:55:25Z")

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Hi all! Exciting news: our JuliaCon BoF proposal for live streaming was accepted to JuliaCon 2021! I have been reaching out to members of our Julia community and elsewhere to get some feedback on what would make a good …

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## [Fastest way of contracting arrays](https://discourse.julialang.org/t/fastest-way-of-contracting-arrays/64415)

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**Author:** [@Frisus95](https://discourse.julialang.org/u/Frisus95)\
**Replies:** 8\
**Last updated:** [July 10, 2021, 5:44pm UTC](https://discourse.julialang.org/t/fastest-way-of-contracting-arrays/64415 "2021-07-10T17:44:43Z")

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Good afternoon everyone! I have the following piece of code, which essentially contracts some multidimensional arrays along specific dimensions (this is a no-sense example, which has the only purpose of illustrating cle…

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## [Why Mosek can not resolve new model when the added new constraints include SOCP constraints?](https://discourse.julialang.org/t/why-mosek-can-not-resolve-new-model-when-the-added-new-constraints-include-socp-constraints/64411)

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**Author:** [@Sawyer\_Zhou](https://discourse.julialang.org/u/Sawyer_Zhou)\
**Replies:** 1\
**Last updated:** [July 10, 2021, 4:18pm UTC](https://discourse.julialang.org/t/why-mosek-can-not-resolve-new-model-when-the-added-new-constraints-include-socp-constraints/64411 "2021-07-10T16:18:38Z")

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Here is a mini-case of my mathematical model. First, solve the initial model, and check if the solution meets the condition. If it does not, the new constraints will be added, and solve the new model. But there are som…

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## [Get access to 7×0 view](https://discourse.julialang.org/t/get-access-to-7x0-view/64419)

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**Author:** [@mhex](https://discourse.julialang.org/u/mhex)\
**Replies:** 1\
**Last updated:** [July 10, 2021, 2:04pm UTC](https://discourse.julialang.org/t/get-access-to-7x0-view/64419 "2021-07-10T14:04:52Z")

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Hi, could anyone show me how to get the values of this 7x0 view, please: debug\> x 7×0 view(::Matrix{Float32}, :, 1:0) with eltype Float32 I have already tried debug\> x\[:\] Float32\[\] debug\> x\[:,:\] 7×0 Matrix{Float32} …

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## [Get individual frames of an \`Animation\` object](https://discourse.julialang.org/t/get-individual-frames-of-an-animation-object/64310)

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**Author:** [@maxkapur](https://discourse.julialang.org/u/maxkapur)\
**Replies:** 2\
**Last updated:** [July 10, 2021, 11:19am UTC](https://discourse.julialang.org/t/get-individual-frames-of-an-animation-object/64310 "2021-07-10T11:19:54Z")

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Here is an example from the Plots documentation: using Plots @userplot CirclePlot @recipe function f(cp::CirclePlot) x, y, i = cp.args n = length(x) inds = circshift(1:n, 1 - i) linewidth --\> range(0, 1…

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## [What's wrong with my chi-squared goodness of fits tests?](https://discourse.julialang.org/t/whats-wrong-with-my-chi-squared-goodness-of-fits-tests/64334)

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**Author:** [@sylvaticus](https://discourse.julialang.org/u/sylvaticus)\
**Replies:** 5\
**Last updated:** [July 10, 2021, 9:47am UTC](https://discourse.julialang.org/t/whats-wrong-with-my-chi-squared-goodness-of-fits-tests/64334 "2021-07-10T09:47:11Z")

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Hi there. I am following a MOOC where I am learning goodness of fits tests, in particular the chi-square test for discrete rv and the Kolmogorov-Smirnov test for continuous rv. I implemented the tests in the following c…

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## [Trouble when I want to fit the model](https://discourse.julialang.org/t/trouble-when-i-want-to-fit-the-model/64406)

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**Author:** [@Marbunnn09](https://discourse.julialang.org/u/Marbunnn09)\
**Replies:** 0\
**Last updated:** [July 10, 2021, 9:01am UTC](https://discourse.julialang.org/t/trouble-when-i-want-to-fit-the-model/64406 "2021-07-10T09:01:21Z")

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Hi Everyone Right now, I’m building the GRU model in Julia by using PyCall with Keras Package from Python. When I want to fit the model then I got the problem issue. this is my code # The GRU architecture model\_GRU = …

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## [ModernGL basics: compile shader](https://discourse.julialang.org/t/moderngl-basics-compile-shader/64393)

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**Author:** [@L\_Adam](https://discourse.julialang.org/u/L_Adam)\
**Replies:** 5\
**Last updated:** [July 10, 2021, 3:17am UTC](https://discourse.julialang.org/t/moderngl-basics-compile-shader/64393 "2021-07-10T03:17:07Z")

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I’m getting confused by ModernGL API. It would due to i’m new to using ccall and pointer in julia i’m new to opengl i try some code found in this repo, specifically the simplest part: triangle const vert\_source = """…

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## [Exporting Excel data to an already existing .xlsx file](https://discourse.julialang.org/t/exporting-excel-data-to-an-already-existing-xlsx-file/19790)

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**Author:** [@ale](https://discourse.julialang.org/u/ale)\
**Replies:** 9\
**Last updated:** [July 10, 2021, 2:21am UTC](https://discourse.julialang.org/t/exporting-excel-data-to-an-already-existing-xlsx-file/19790 "2021-07-10T02:21:08Z")

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Hi, I am trying to export different arrays to different sheets of an already existing Excel file. The format of this file is .xlsx. Since I need to have several sheets in the same file, I can’t use “CSV”. Secondly, it…

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## [(Spanish) tutorial about fundamentals of classical molecular dynamics simulations](https://discourse.julialang.org/t/spanish-tutorial-about-fundamentals-of-classical-molecular-dynamics-simulations/64391)

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**Author:** [@lmiq](https://discourse.julialang.org/u/lmiq)\
**Replies:** 0\
**Last updated:** [July 10, 2021, 1:55am UTC](https://discourse.julialang.org/t/spanish-tutorial-about-fundamentals-of-classical-molecular-dynamics-simulations/64391 "2021-07-10T01:55:19Z")

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I will be teaching next week a short course on the fundamentals of classical molecular dynamics as part of an initiative from the University of Buenos Aires (https://sites.google.com/view/simulacionenquimica/), and for t…

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## [Dockerhub Julia Dockerfile using Outdated Key Server](https://discourse.julialang.org/t/dockerhub-julia-dockerfile-using-outdated-key-server/64381)

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**Author:** [@Satvik](https://discourse.julialang.org/u/Satvik)\
**Replies:** 3\
**Last updated:** [July 10, 2021, 1:09am UTC](https://discourse.julialang.org/t/dockerhub-julia-dockerfile-using-outdated-key-server/64381 "2021-07-10T01:09:14Z")

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Hi, I wasn’t sure where to file this, but when trying to set up the Julia 1.6.1 docker image, I got the following error: gpg: keyserver receive failed: No name Googling around a bit, it looks like the keyserver the Do…

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## [For web scrapers masters](https://discourse.julialang.org/t/for-web-scrapers-masters/64388)

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**Author:** [@joa-quim](https://discourse.julialang.org/u/joa-quim)\
**Replies:** 6\
**Last updated:** [July 9, 2021, 11:59pm UTC](https://discourse.julialang.org/t/for-web-scrapers-masters/64388 "2021-07-09T23:59:49Z")

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Hi, This week Nature’s images has one, among others (the sleeping Elephants is so sweet) that is truly spectacular. I’ll call it the Van Gogh’s paddlers. But, damn it, the browsers manage to prevent us from saving the p…

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## [Readline() and end-of-file](https://discourse.julialang.org/t/readline-and-end-of-file/64384)

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**Author:** [@lmiq](https://discourse.julialang.org/u/lmiq)\
**Replies:** 6\
**Last updated:** [July 9, 2021, 10:10pm UTC](https://discourse.julialang.org/t/readline-and-end-of-file/64384 "2021-07-09T22:10:59Z")

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I need to read a file with a loop that is something like this: file = open("file.txt","r") while true length(readline(file)) == 0 && break # ignore this line and exit if file ended?? for i in 1:n line = read…

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## [How to merge 2 dataframes (DataFrames.jl)](https://discourse.julialang.org/t/how-to-merge-2-dataframes-dataframes-jl/64321)

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**Author:** [@Based](https://discourse.julialang.org/u/Based)\
**Replies:** 5\
**Last updated:** [July 9, 2021, 10:03pm UTC](https://discourse.julialang.org/t/how-to-merge-2-dataframes-dataframes-jl/64321 "2021-07-09T22:03:06Z")

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I have 2 dataframes. Each contains independent datapoints in different rows with different IDs. They share most of the same columns, except for one. I want to combine them into one data frame. I feel like there should be…

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## [Creating User-Defined Grouped DataFrames](https://discourse.julialang.org/t/creating-user-defined-grouped-dataframes/64387)

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**Author:** [@TheCedarPrince](https://discourse.julialang.org/u/TheCedarPrince)\
**Replies:** 1\
**Last updated:** [July 9, 2021, 9:13pm UTC](https://discourse.julialang.org/t/creating-user-defined-grouped-dataframes/64387 "2021-07-09T21:13:20Z")

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Hi all, Just wanted to post a little snippet I learned from @kevbonham about how to create user-defined grouped data frames. What I mean by this, is I was working with time series data recently and wanted to generate gr…

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## [How do I reload a module under development in Julia 1.6?](https://discourse.julialang.org/t/how-do-i-reload-a-module-under-development-in-julia-1-6/64377)

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**Author:** [@orome](https://discourse.julialang.org/u/orome)\
**Replies:** 3\
**Last updated:** [July 9, 2021, 8:41pm UTC](https://discourse.julialang.org/t/how-do-i-reload-a-module-under-development-in-julia-1-6/64377 "2021-07-09T20:41:15Z")

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I know this question has been asked and answered before, but none of the many answers work for me as described. What is the procedure for reloading a module that I’m working on in Julia (1.6)? For example, I have modu…

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## [Triangulation for Cloth Simulation](https://discourse.julialang.org/t/triangulation-for-cloth-simulation/64375)

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**Author:** [@graham](https://discourse.julialang.org/u/graham)\
**Replies:** 6\
**Last updated:** [July 9, 2021, 8:30pm UTC](https://discourse.julialang.org/t/triangulation-for-cloth-simulation/64375 "2021-07-09T20:30:02Z")

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Hi all, I’m working on porting over my implementation of the seminal cloth simulator designed by Baraff and Witkin. As first steps, I’m trying to generate a flat plane, triangulated with approximately evenly spaced node…

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## [Use two system images programmatically in C](https://discourse.julialang.org/t/use-two-system-images-programmatically-in-c/64374)

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**Author:** [@benoit](https://discourse.julialang.org/u/benoit)\
**Replies:** 0\
**Last updated:** [July 9, 2021, 6:34pm UTC](https://discourse.julialang.org/t/use-two-system-images-programmatically-in-c/64374 "2021-07-09T18:34:50Z")

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I saw that it is possible to boot Julia with up to 2 sysimages by using the -J argument. I was wondering if it possible to do the same thing programmatically in C? I did not see any options other than jl\_options.image\_…

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## [Argument passing with dataframes](https://discourse.julialang.org/t/argument-passing-with-dataframes/64355)

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**Author:** [@Mastomaki](https://discourse.julialang.org/u/Mastomaki)\
**Replies:** 4\
**Last updated:** [July 9, 2021, 6:10pm UTC](https://discourse.julialang.org/t/argument-passing-with-dataframes/64355 "2021-07-09T18:10:29Z")

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Hello! I am wondering the following with dataframes: function addcol1(x) x.mycol = x.ID .+ 1 end function join1(x) jobs = DataFrame(ID = \[20, 40,45\], Job = \["Lawyer", "Doctor","teacher"\]) x = innerjoin(x, jobs, on …

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## [Scientific notation + sum() function](https://discourse.julialang.org/t/scientific-notation-sum-function/64368)

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**Author:** [@Alex\_Tantos](https://discourse.julialang.org/u/Alex_Tantos)\
**Replies:** 3\
**Last updated:** [July 9, 2021, 6:08pm UTC](https://discourse.julialang.org/t/scientific-notation-sum-function/64368 "2021-07-09T18:08:58Z")

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Hi there! As part of getting to know the language I am preparing the code for the softmax function and I just found out that the sum() function does not return the expected result when some of the numbers of a vector are…

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## [PlotlyJS’s parallel coordinates plot](https://discourse.julialang.org/t/plotlyjs-s-parallel-coordinates-plot/64371)

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**Author:** [@saraflgarcia](https://discourse.julialang.org/u/saraflgarcia)\
**Replies:** 0\
**Last updated:** [July 9, 2021, 6:05pm UTC](https://discourse.julialang.org/t/plotlyjs-s-parallel-coordinates-plot/64371 "2021-07-09T18:05:39Z")

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Hi there, I’m using Julia with PlotlyJS’s parallel coordinates plot. Is there any way to use string values? Plot(PlotlyJS.parcoords(dimensions=\[attr(range =\[1,5\], label = "A", values = \[4,2\]), attr(label =…

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## [Julia ecosystem == Jungle?](https://discourse.julialang.org/t/julia-ecosystem-jungle/64326)

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**Author:** [@Bardo](https://discourse.julialang.org/u/Bardo)\
**Replies:** 6\
**Last updated:** [July 9, 2021, 5:18pm UTC](https://discourse.julialang.org/t/julia-ecosystem-jungle/64326 "2021-07-09T17:18:42Z")

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Hi, I’m struggling to find my way in this jungle… Objective: Build an event-based simulator in Julia. I have coded one in Matlab, now looking for speed. Instead of simple translating, I looked how others do it. Reac…

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## [Testing a Package: Warning about test dependency](https://discourse.julialang.org/t/testing-a-package-warning-about-test-dependency/64363)

<div class="topic-metadata">

**Author:** [@v-i-s-h](https://discourse.julialang.org/u/v-i-s-h)\
**Replies:** 1\
**Last updated:** [July 9, 2021, 5:05pm UTC](https://discourse.julialang.org/t/testing-a-package-warning-about-test-dependency/64363 "2021-07-09T17:05:35Z")

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Hi, I am working on a package (GitHub - v-i-s-h/Runner.jl: Provides \`@runit\` macro for running scripts with commandline arguments from REPL) and also wrote some test cases. When I tried to test it through pkg \> test, I…

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## [Replace non ascii char](https://discourse.julialang.org/t/replace-non-ascii-char/64358)

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**Author:** [@agatheLG](https://discourse.julialang.org/u/agatheLG)\
**Replies:** 2\
**Last updated:** [July 9, 2021, 4:44pm UTC](https://discourse.julialang.org/t/replace-non-ascii-char/64358 "2021-07-09T16:44:59Z")

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Hi, I am switching a lot between format from dataframe to csv file to sql and of course I have an error about invalid character (Base.InvalidCharError{Char}(‘\\x8e’) when I try to load my data into SQL. I can indeed see…

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## [How to retrieve more results from NEOS Server?](https://discourse.julialang.org/t/how-to-retrieve-more-results-from-neos-server/64222)

<div class="topic-metadata">

**Author:** [@fredih](https://discourse.julialang.org/u/fredih)\
**Replies:** 5\
**Last updated:** [July 9, 2021, 4:32pm UTC](https://discourse.julialang.org/t/how-to-retrieve-more-results-from-neos-server/64222 "2021-07-09T16:32:46Z")

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Hello! How can I retrieve the variable values from the NEOS server? Currently I only receive the objective function value in my e-mail. For example, to this code: using JuMP, NamedArrays, Cbc, NEOSServer threath = Mod…

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