# Latest

**URL:** https://discourse.julialang.org/latest.md?page=984

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

**Page:** 985

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## [VideoIO.jl can’t seem to open a .mkv video](https://discourse.julialang.org/t/videoio-jl-can-t-seem-to-open-a-mkv-video/83875)

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**Author:** [@Hareruya](https://discourse.julialang.org/u/Hareruya)\
**Replies:** 13\
**Last updated:** [July 12, 2022, 6:53am UTC](https://discourse.julialang.org/t/videoio-jl-can-t-seem-to-open-a-mkv-video/83875 "2022-07-12T06:53:53Z")

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Greetings. I do image signal processing as a hobby, especially playing around with images taken from video. I used to take screenshots using MPV, but I started to wonder if it would not be better to take shots from with…

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## [PlotlyJS 3D Annotations](https://discourse.julialang.org/t/plotlyjs-3d-annotations/84048)

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**Author:** [@Freya\_the\_Goddess](https://discourse.julialang.org/u/Freya_the_Goddess)\
**Replies:** 2\
**Last updated:** [July 12, 2022, 7:37am UTC](https://discourse.julialang.org/t/plotlyjs-3d-annotations/84048 "2022-07-12T07:37:10Z")

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Hi all, I am playing around with this PlotlyJS, I want to know: how to change the marker color so each can have different color. how to change the label of x,y,z ? x is for years, y is for pandemics, and z is for Deat…

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## [Jmathplot via JavaCall.jl](https://discourse.julialang.org/t/jmathplot-via-javacall-jl/69686)

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**Author:** [@Bardo](https://discourse.julialang.org/u/Bardo)\
**Replies:** 3\
**Last updated:** [October 13, 2021, 8:37pm UTC](https://discourse.julialang.org/t/jmathplot-via-javacall-jl/69686 "2021-10-13T20:37:57Z")

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Hi, would be glad if someone could give a hand with the example from https://github.com/yannrichet/jmathplot. jmathplot.jar is in https://github.com/yannrichet/jmathplot/tree/master/dist Got lost in the calling synta…

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## [Make Documenter.jl understand where to search local markdown links](https://discourse.julialang.org/t/make-documenter-jl-understand-where-to-search-local-markdown-links/84012)

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**Author:** [@Lecrapouille](https://discourse.julialang.org/u/Lecrapouille)\
**Replies:** 5\
**Last updated:** [July 12, 2022, 6:33am UTC](https://discourse.julialang.org/t/make-documenter-jl-understand-where-to-search-local-markdown-links/84012 "2022-07-12T06:33:43Z")

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Hi ! I’m working on my git branch dev for my MyProject.jl project. The README.md is placed at the root of my like any GitHub project it and is referring to a local folder ./tutorial. For example: See my \[tutorial\](tutor…

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## [Sample from csv to build surrogate model](https://discourse.julialang.org/t/sample-from-csv-to-build-surrogate-model/84031)

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**Author:** [@chenr86](https://discourse.julialang.org/u/chenr86)\
**Replies:** 4\
**Last updated:** [July 12, 2022, 6:15am UTC](https://discourse.julialang.org/t/sample-from-csv-to-build-surrogate-model/84031 "2022-07-12T06:15:30Z")

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Hello I attempt to use Surrogate.jl to build a surrogate model of a set of measurement data, coming from a csv file. For the model, there will be 5 inputs and 1 output. I review the user manual of Surrogate.jl and I fin…

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## [Add varargs... to generic function](https://discourse.julialang.org/t/add-varargs-to-generic-function/84046)

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**Author:** [@Lincoln\_Hannah](https://discourse.julialang.org/u/Lincoln_Hannah)\
**Replies:** 3\
**Last updated:** [July 12, 2022, 5:59am UTC](https://discourse.julialang.org/t/add-varargs-to-generic-function/84046 "2022-07-12T05:59:35Z")

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Is there a function that can take any kwargs function and return the same function with a varargs… parameter? That is convert f(; a ) = 1 to f(; a, X... ) = 1 and f(; a,b,c ) = a+b+c to f(; a,b,c, X... ) = a+b+…

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## [Convert dataframe to array of tuples](https://discourse.julialang.org/t/convert-dataframe-to-array-of-tuples/84085)

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**Author:** [@chenr86](https://discourse.julialang.org/u/chenr86)\
**Replies:** 1\
**Last updated:** [July 12, 2022, 5:47am UTC](https://discourse.julialang.org/t/convert-dataframe-to-array-of-tuples/84085 "2022-07-12T05:47:03Z")

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Hello, I have a dataframe of 2 columns reading from csv file, how can I convert each line of dataframe into a tuple, and combine all the tuples to form like Array{Tuple{Float64, Float64}} or Vector{Tuple{Float64, Float6…

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## [Embedding Julia in the Java Virtual Machine](https://discourse.julialang.org/t/embedding-julia-in-the-java-virtual-machine/51444)

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**Author:** [@mkitti](https://discourse.julialang.org/u/mkitti)\
**Replies:** 11\
**Last updated:** [October 5, 2021, 1:55pm UTC](https://discourse.julialang.org/t/embedding-julia-in-the-java-virtual-machine/51444 "2021-10-05T13:55:06Z")

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Is it easier to embed Julia into the Java Virtual Machine (JVM) or easier to embed the JVM into Julia? Embedding the JVM into Julia I’ve been working with @avik on JavaCall.jl for the better part of this year. To make …

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## [When Zygote.jl meets Quadgk.jl: Mutating arrays is not supported -- called setindex!(::Vector{QuadGK.Segment})](https://discourse.julialang.org/t/when-zygote-jl-meets-quadgk-jl-mutating-arrays-is-not-supported-called-setindex-vector-quadgk-segment/84042)

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**Author:** [@F-YF](https://discourse.julialang.org/u/F-YF)\
**Replies:** 6\
**Last updated:** [July 12, 2022, 5:14am UTC](https://discourse.julialang.org/t/when-zygote-jl-meets-quadgk-jl-mutating-arrays-is-not-supported-called-setindex-vector-quadgk-segment/84042 "2022-07-12T05:14:15Z")

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I have a problem calculating the derivative of a function that involves an integral operation. Examples are as follows: using QuadGK using Zygote function test() f(t)=quadgk(x-\>sin(x)\*exp(t\*cos(x)) , 0, pi, atol=1…

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## [Finding Derivative of 2 arrays of numbers Using Zygote](https://discourse.julialang.org/t/finding-derivative-of-2-arrays-of-numbers-using-zygote/83822)

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**Author:** [@alegeaa](https://discourse.julialang.org/u/alegeaa)\
**Replies:** 15\
**Last updated:** [July 12, 2022, 4:36am UTC](https://discourse.julialang.org/t/finding-derivative-of-2-arrays-of-numbers-using-zygote/83822 "2022-07-12T04:36:49Z")

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Hello, Please I am working on a physical system, and after running simulations I have 2 arrays of variables like this: D = \[0.01, 0.02, …, 0.05\] m = \[1, 2, …, 5\] Please how do I find the derivative (∂D/∂m) using Zygo…

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## [Type instability in Folds.map](https://discourse.julialang.org/t/type-instability-in-folds-map/84080)

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**Author:** [@MattSainsbury-Dale](https://discourse.julialang.org/u/MattSainsbury-Dale)\
**Replies:** 0\
**Last updated:** [July 12, 2022, 3:54am UTC](https://discourse.julialang.org/t/type-instability-in-folds-map/84080 "2022-07-12T03:54:28Z")

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Hello, I’ve noticed that the Folds version of map() seems to introduce type instability: using Folds f1(K::Integer) = map(identity, 1:K) f2(K::Integer) = Folds.map(identity, 1:K) @code\_warntype f1(5) @code\_warntype f…

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## [Annotations using Package Gaston](https://discourse.julialang.org/t/annotations-using-package-gaston/84076)

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**Author:** [@angeloaliano1](https://discourse.julialang.org/u/angeloaliano1)\
**Replies:** 0\
**Last updated:** [July 11, 2022, 11:46pm UTC](https://discourse.julialang.org/t/annotations-using-package-gaston/84076 "2022-07-11T23:46:41Z")

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Dear all, I have the code to plot a graph using Gaston using Gaston L=\[1 2;3 4\] scatter(L\[1:1,1\], L\[1:1,2\],linewidth="3", pointtype="fsquare", plotstyle="linespoints",Axes(key = :off)) How can I do a annotation at rig…

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## [Dispatching on type alias](https://discourse.julialang.org/t/dispatching-on-type-alias/84035)

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**Author:** [@torrance](https://discourse.julialang.org/u/torrance)\
**Replies:** 2\
**Last updated:** [July 12, 2022, 1:46am UTC](https://discourse.julialang.org/t/dispatching-on-type-alias/84035 "2022-07-12T01:46:55Z")

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I want to create a type alias for the standard array type, i.e.: const MyArray = Array and I want to be able to dispatch on this type in a way that is unique for MyArray, e.g.: function test(::MyArray) println("It…

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## [Joining forwards- and backwards-in-time ODE solutions](https://discourse.julialang.org/t/joining-forwards-and-backwards-in-time-ode-solutions/82071)

<div class="topic-metadata">

**Author:** [@moble](https://discourse.julialang.org/u/moble)\
**Replies:** 5\
**Last updated:** [July 12, 2022, 1:28am UTC](https://discourse.julialang.org/t/joining-forwards-and-backwards-in-time-ode-solutions/82071 "2022-07-12T01:28:56Z")

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As in this question, I’m hoping to combine two ODE solutions, but I really need some of the nice features of the solutions — mostly dense output. And maybe in some ways my problem is easier because I really have the sam…

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## [Struggling to Run Distributed I/O Operations on SLURM Cluster](https://discourse.julialang.org/t/struggling-to-run-distributed-i-o-operations-on-slurm-cluster/84075)

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**Author:** [@TheCedarPrince](https://discourse.julialang.org/u/TheCedarPrince)\
**Replies:** 1\
**Last updated:** [July 12, 2022, 12:40am UTC](https://discourse.julialang.org/t/struggling-to-run-distributed-i-o-operations-on-slurm-cluster/84075 "2022-07-12T00:40:18Z")

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Hi all, Problem Background I have been struggling a couple days to understand parallel and distributed computing on a remote cluster that runs SLURM. I have 100s of huge files that I need to extract information from an…

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## [Dot matrix of parameters of a neural network?](https://discourse.julialang.org/t/dot-matrix-of-parameters-of-a-neural-network/84072)

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**Author:** [@MysteriousStranger](https://discourse.julialang.org/u/MysteriousStranger)\
**Replies:** 1\
**Last updated:** [July 11, 2022, 10:51pm UTC](https://discourse.julialang.org/t/dot-matrix-of-parameters-of-a-neural-network/84072 "2022-07-11T22:51:44Z")

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Hello, I am trying to do the dot product of the parameters of a Zygote neural network times some big matrix: params = best\_model |\> Flux.params dot( params\[1\], big\_matrix) but I am getting this error message: Scal…

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## [Matrix Column/Row Labelling](https://discourse.julialang.org/t/matrix-column-row-labelling/84064)

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**Author:** [@xztt](https://discourse.julialang.org/u/xztt)\
**Replies:** 3\
**Last updated:** [July 11, 2022, 10:17pm UTC](https://discourse.julialang.org/t/matrix-column-row-labelling/84064 "2022-07-11T22:17:31Z")

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Hi, Is there a simple way of assigning labels to matrix columns such that if operations are performed to that matrix you still can see where that specific column has ended up for example reduced row echelon or if I perf…

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## [Represent dimensions with primes](https://discourse.julialang.org/t/represent-dimensions-with-primes/84029)

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**Author:** [@dmoored4](https://discourse.julialang.org/u/dmoored4)\
**Replies:** 3\
**Last updated:** [July 11, 2022, 8:59pm UTC](https://discourse.julialang.org/t/represent-dimensions-with-primes/84029 "2022-07-11T20:59:22Z")

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I use Unitful in every single project so this is not to suggest that there is any kind of inadequacy! More of just a thought exercise. I was wondering if there would be any benefit if the different core dimensions were r…

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## [I need to convert these parallel robot algorithms to Julia from Matlab, but I cannot get the forward kinematics to work](https://discourse.julialang.org/t/i-need-to-convert-these-parallel-robot-algorithms-to-julia-from-matlab-but-i-cannot-get-the-forward-kinematics-to-work/83835)

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**Author:** [@Mervyn\_Larrier](https://discourse.julialang.org/u/Mervyn_Larrier)\
**Replies:** 20\
**Last updated:** [July 11, 2022, 8:02pm UTC](https://discourse.julialang.org/t/i-need-to-convert-these-parallel-robot-algorithms-to-julia-from-matlab-but-i-cannot-get-the-forward-kinematics-to-work/83835 "2022-07-11T20:02:16Z")

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I’ve been trying for over a week to translate this Matlab code into Julia. I’ve got the inverse kinematics, Jacobian, and other associate scripts translated. But this FK script is being a colossal pain. A link to videos …

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## [@benchmark takes extra long time](https://discourse.julialang.org/t/benchmark-takes-extra-long-time/84056)

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**Author:** [@Daniel\_Scheinerman](https://discourse.julialang.org/u/Daniel_Scheinerman)\
**Replies:** 2\
**Last updated:** [July 11, 2022, 7:51pm UTC](https://discourse.julialang.org/t/benchmark-takes-extra-long-time/84056 "2022-07-11T19:51:01Z")

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I have found that @benchmark takes an exceptionally long (additional) time to run when the computation it is timing is more than a second or so. Here is an example: julia\> using Combinatorics function sum\_subsets(A) …

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## [Error: I cannot install package Meshes](https://discourse.julialang.org/t/error-i-cannot-install-package-meshes/84051)

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**Author:** [@evandro.schulz](https://discourse.julialang.org/u/evandro.schulz)\
**Replies:** 8\
**Last updated:** [July 11, 2022, 7:34pm UTC](https://discourse.julialang.org/t/error-i-cannot-install-package-meshes/84051 "2022-07-11T19:34:20Z")

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Hi, I’m a new user and I have had problems with scripts that use the command Point3f, Point2f and others to generate plots. Well, apparently, the problem is caused by errors in packages installation. I uninstalled the Ju…

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## [Changing field with a function in a mutable struct](https://discourse.julialang.org/t/changing-field-with-a-function-in-a-mutable-struct/84006)

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**Author:** [@RicardoFR](https://discourse.julialang.org/u/RicardoFR)\
**Replies:** 9\
**Last updated:** [July 11, 2022, 7:25pm UTC](https://discourse.julialang.org/t/changing-field-with-a-function-in-a-mutable-struct/84006 "2022-07-11T19:25:16Z")

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Hello all! I have a mutable struct that must carry a function in one of its fields. Once I assign it to a variable, however, I cannot change the function. Here’s an example: mutable struct Foo{T\<:Real,F\<:Function} …

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## [Color opacity](https://discourse.julialang.org/t/color-opacity/84063)

<div class="topic-metadata">

**Author:** [@ahmed](https://discourse.julialang.org/u/ahmed)\
**Replies:** 5\
**Last updated:** [July 11, 2022, 6:50pm UTC](https://discourse.julialang.org/t/color-opacity/84063 "2022-07-11T18:50:55Z")

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I have a variable that I would like to assign the color red to it simply by using RGB{Float64}(1, 0, 0) but I’d like the absolute value of the variable to determine the opacity of the color. How can one change the color…

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## [JuliaSurveyForm: JuliaCon Survery Form generated from Julia](https://discourse.julialang.org/t/juliasurveyform-juliacon-survery-form-generated-from-julia/84068)

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**Author:** [@Roger-luo](https://discourse.julialang.org/u/Roger-luo)\
**Replies:** 0\
**Last updated:** [July 11, 2022, 6:33pm UTC](https://discourse.julialang.org/t/juliasurveyform-juliacon-survery-form-generated-from-julia/84068 "2022-07-11T18:33:34Z")

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We translate new questions for JuliaCon survey every year, which has been a bit painful since it’s hard to look for differences between the previous year and the new survey and keep track of the translation and updates o…

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## [Simple vector algebra with Symbolics/SymbolicUtils](https://discourse.julialang.org/t/simple-vector-algebra-with-symbolics-symbolicutils/79054)

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**Author:** [@nchisholm](https://discourse.julialang.org/u/nchisholm)\
**Replies:** 6\
**Last updated:** [July 11, 2022, 6:21pm UTC](https://discourse.julialang.org/t/simple-vector-algebra-with-symbolics-symbolicutils/79054 "2022-07-11T18:21:38Z")

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I am trying to define a simple symbolic vector type to use with the Symbolics and/or SymbolicUtils packages. I have looked through the documentation of these packages, but I am still at a loss. I am aware that Symbolic…

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## [Julia shell and Windows shell (cmd) giving different result](https://discourse.julialang.org/t/julia-shell-and-windows-shell-cmd-giving-different-result/84053)

<div class="topic-metadata">

**Author:** [@Brad\_Carman](https://discourse.julialang.org/u/Brad_Carman)\
**Replies:** 4\
**Last updated:** [July 11, 2022, 5:47pm UTC](https://discourse.julialang.org/t/julia-shell-and-windows-shell-cmd-giving-different-result/84053 "2022-07-11T17:47:49Z")

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I am attempting to call xelatex from Julia’s run() function. For some reason I am getting a missing fonts error when running this from Julia. When running the same command (from the same location) in Windows cmd, the d…

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## [Software Development Engineer at AWS Center for Quantum Computing](https://discourse.julialang.org/t/software-development-engineer-at-aws-center-for-quantum-computing/84062)

<div class="topic-metadata">

**Author:** [@ajkeller34](https://discourse.julialang.org/u/ajkeller34)\
**Replies:** 0\
**Last updated:** [July 11, 2022, 4:34pm UTC](https://discourse.julialang.org/t/software-development-engineer-at-aws-center-for-quantum-computing/84062 "2022-07-11T16:34:09Z")

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The AWS Center for Quantum Computing is hiring a software engineer with expertise in electronic computer-aided design automation, computational geometry, and/or research software engineering. Working in a team of scienti…

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## [What is the standard Markdown implementation for Julia?](https://discourse.julialang.org/t/what-is-the-standard-markdown-implementation-for-julia/84059)

<div class="topic-metadata">

**Author:** [@cadojo](https://discourse.julialang.org/u/cadojo)\
**Replies:** 1\
**Last updated:** [July 11, 2022, 4:28pm UTC](https://discourse.julialang.org/t/what-is-the-standard-markdown-implementation-for-julia/84059 "2022-07-11T16:28:05Z")

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I had remembered that Markdown.jl is the standard implementation of Markdown in Julia. I am working on a MyST-markdown wrapper in Julia, and I’m trying to see what the other implementations are. I see Markdown.jl is par…

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## [Why XLSX.readxlsx not working?](https://discourse.julialang.org/t/why-xlsx-readxlsx-not-working/84052)

<div class="topic-metadata">

**Author:** [@Optimization](https://discourse.julialang.org/u/Optimization)\
**Replies:** 4\
**Last updated:** [July 11, 2022, 3:35pm UTC](https://discourse.julialang.org/t/why-xlsx-readxlsx-not-working/84052 "2022-07-11T15:35:39Z")

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I’m trying to read a first column of an excel file (from sheet2 column d2). This is my try: using XLSX, , DataFrames xf = XLSX.readxlsx("C:/Data/sample.xlsx") sh = xf\["sheet2"\] sh\["d2"\] ; sh\[3\]; # or any other simila…

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## [\`im\` as global constant](https://discourse.julialang.org/t/im-as-global-constant/84055)

<div class="topic-metadata">

**Author:** [@kurt](https://discourse.julialang.org/u/kurt)\
**Replies:** 2\
**Last updated:** [July 11, 2022, 3:22pm UTC](https://discourse.julialang.org/t/im-as-global-constant/84055 "2022-07-11T15:22:10Z")

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Where is im as a global constant defined? I’ve checked base.jl, complex.jl and mathconsts.jl. I cant seem to find it. Help would be appreciated. Thank you

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