# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1187

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

**Page:** 1188

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## [Understanding DCP in Convex.jl and the difference of elapsed time](https://discourse.julialang.org/t/understanding-dcp-in-convex-jl-and-the-difference-of-elapsed-time/72626)

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**Author:** [@iHany](https://discourse.julialang.org/u/iHany)\
**Replies:** 8\
**Last updated:** [December 6, 2021, 2:38am UTC](https://discourse.julialang.org/t/understanding-dcp-in-convex-jl-and-the-difference-of-elapsed-time/72626 "2021-12-06T02:38:06Z")

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Hi, there! I’d like to understand why the following elapsed times to solve the following two problems are significantly different. Here is my code and the result (to avoid high latency due to JIT compile, the results a…

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## [NLP parameters inside a multithreaded loop](https://discourse.julialang.org/t/nlp-parameters-inside-a-multithreaded-loop/72622)

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**Author:** [@Joao\_Guilherme\_Santo](https://discourse.julialang.org/u/Joao_Guilherme_Santo)\
**Replies:** 2\
**Last updated:** [December 6, 2021, 12:06am UTC](https://discourse.julialang.org/t/nlp-parameters-inside-a-multithreaded-loop/72622 "2021-12-06T00:06:51Z")

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I am not sure if this is a JuMP or NLopt issue but whenever I try to do a loop with a NLP inside defining a parameter in each iteration, it only works if I am using a single thread. For example, the code below does not …

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## [Jlrs 0.13: LTS, stable, Windows, tokio, and plotting support](https://discourse.julialang.org/t/jlrs-0-13-lts-stable-windows-tokio-and-plotting-support/72616)

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**Author:** [@Taaitaaiger](https://discourse.julialang.org/u/Taaitaaiger)\
**Replies:** 1\
**Last updated:** [December 5, 2021, 11:01pm UTC](https://discourse.julialang.org/t/jlrs-0-13-lts-stable-windows-tokio-and-plotting-support/72616 "2021-12-05T23:01:57Z")

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jlrs is a crate for the Rust programming language that provides bindings to the Julia C API. As you’re probably well aware, last week a new stable version of Julia was released, version 1.7, and version 1.6 was designate…

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## [Parallel pre-calculation of optimization model](https://discourse.julialang.org/t/parallel-pre-calculation-of-optimization-model/72547)

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**Author:** [@kchnkrml](https://discourse.julialang.org/u/kchnkrml)\
**Replies:** 8\
**Last updated:** [December 5, 2021, 10:45pm UTC](https://discourse.julialang.org/t/parallel-pre-calculation-of-optimization-model/72547 "2021-12-05T22:45:54Z")

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I have got a rather large optimization problem, where creating the model (and writing an .lp file or passing it to a solver) takes a substantial amount of time (a few days), while solving it is (comparatively) quick. Sin…

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## [Massive crash](https://discourse.julialang.org/t/massive-crash/72552)

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**Author:** [@lewis](https://discourse.julialang.org/u/lewis)\
**Replies:** 6\
**Last updated:** [December 5, 2021, 9:23pm UTC](https://discourse.julialang.org/t/massive-crash/72552 "2021-12-05T21:23:29Z")

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This is very hard to figure out. I’ll try the debugger to find the exact line that crashes. Most of the code works, but there is new code that is run based on one input parameter, so I at least know what code file causes…

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## [ Why can't I use julia addprocs?(ECONNREFUSED)](https://discourse.julialang.org/t/why-cant-i-use-julia-addprocs-econnrefused/72477)

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**Author:** [@GalloLuigi](https://discourse.julialang.org/u/GalloLuigi)\
**Replies:** 19\
**Last updated:** [December 5, 2021, 8:51pm UTC](https://discourse.julialang.org/t/why-cant-i-use-julia-addprocs-econnrefused/72477 "2021-12-05T20:51:09Z")

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I’m writing a program that should connect to remote virtual machines and then do distributed execution. I have this warning: “Warning: Identity file /home/luigal/.ssh/id\_rsa not accessible: No such file or directory.”.(…

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## [Reimagining C++ project in Julia: arrays and structs vs data frames](https://discourse.julialang.org/t/reimagining-c-project-in-julia-arrays-and-structs-vs-data-frames/71435)

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**Author:** [@bjdaig](https://discourse.julialang.org/u/bjdaig)\
**Replies:** 23\
**Last updated:** [December 5, 2021, 8:46pm UTC](https://discourse.julialang.org/t/reimagining-c-project-in-julia-arrays-and-structs-vs-data-frames/71435 "2021-12-05T20:46:10Z")

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I have a working C++ project that involves reading in several different CSV files, some with header info, and some more like tables. Most of the data is record-like with “stn\_id” for column 1, followed by other column d…

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## [Cannot import function in Pluto](https://discourse.julialang.org/t/cannot-import-function-in-pluto/72608)

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**Author:** [@Christopher\_Fisher](https://discourse.julialang.org/u/Christopher_Fisher)\
**Replies:** 3\
**Last updated:** [December 5, 2021, 8:17pm UTC](https://discourse.julialang.org/t/cannot-import-function-in-pluto/72608 "2021-12-05T20:17:23Z")

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Hi all, I recieve an error indicating multiple function definitions when I import a function and define a method. The attached image shows a simple example. Am I doing something incorrectly? Version Julia 1.7 Plut…

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## [How to pass each column of a Matrix(which is the output of an NN) onto a layer seperately](https://discourse.julialang.org/t/how-to-pass-each-column-of-a-matrix-which-is-the-output-of-an-nn-onto-a-layer-seperately/72574)

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**Author:** [@Qfl3x](https://discourse.julialang.org/u/Qfl3x)\
**Replies:** 2\
**Last updated:** [December 5, 2021, 4:46pm UTC](https://discourse.julialang.org/t/how-to-pass-each-column-of-a-matrix-which-is-the-output-of-an-nn-onto-a-layer-seperately/72574 "2021-12-05T16:46:14Z")

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Hello, I have a net as follows: model = Chain(Embed(200,37),Dense(200,150),Dense(150,100)) The output of Embed (From Transformers.jl) is an embedding matrix of size (200,100) for a size 100 input vector. Meaning at t…

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## [Save figure with transparent background color in Plots.jl](https://discourse.julialang.org/t/save-figure-with-transparent-background-color-in-plots-jl/18808)

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**Author:** [@Shunsuke-Hori](https://discourse.julialang.org/u/Shunsuke-Hori)\
**Replies:** 19\
**Last updated:** [December 5, 2021, 4:40pm UTC](https://discourse.julialang.org/t/save-figure-with-transparent-background-color-in-plots-jl/18808 "2021-12-05T16:40:24Z")

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Is there a way to save a figure with transparent background color in Plots.jl? pyplot can do that by transparent=True.

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## [Valid GeoJSON object for choroplethmapbox Trace](https://discourse.julialang.org/t/valid-geojson-object-for-choroplethmapbox-trace/72592)

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**Author:** [@Dieter](https://discourse.julialang.org/u/Dieter)\
**Replies:** 4\
**Last updated:** [December 5, 2021, 4:28pm UTC](https://discourse.julialang.org/t/valid-geojson-object-for-choroplethmapbox-trace/72592 "2021-12-05T16:28:00Z")

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Hello Community! I try to create a plotly choroplethmapbox using a GeoJSON for the coordinates of the geographical regions and a dataframe containing the values which are used to color the regions. Plotly choroplethmap…

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## [JuMP.jl and DifferentialEquation.jl benchmarks on M1 Max Julia 1.7.0 x89 vs ARM. (spoiler: ARM is 1.5-2x faster)](https://discourse.julialang.org/t/jump-jl-and-differentialequation-jl-benchmarks-on-m1-max-julia-1-7-0-x89-vs-arm-spoiler-arm-is-1-5-2x-faster/72496)

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**Author:** [@DenisTitov](https://discourse.julialang.org/u/DenisTitov)\
**Replies:** 12\
**Last updated:** [December 5, 2021, 4:11pm UTC](https://discourse.julialang.org/t/jump-jl-and-differentialequation-jl-benchmarks-on-m1-max-julia-1-7-0-x89-vs-arm-spoiler-arm-is-1-5-2x-faster/72496 "2021-12-05T16:11:19Z")

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This is just FYI for fun in case people are interested. I compared JuMP, DiffEq and simple sort() on M1 Max MacBook using official binaries of Julia 1.7.0 with either Native ARM or x86 with Rosetta2. Native ARM version…

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## [Strange error from Turing.jl?](https://discourse.julialang.org/t/strange-error-from-turing-jl/68837)

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**Author:** [@dlakelan](https://discourse.julialang.org/u/dlakelan)\
**Replies:** 18\
**Last updated:** [December 5, 2021, 3:22pm UTC](https://discourse.julialang.org/t/strange-error-from-turing-jl/68837 "2021-12-05T15:22:13Z")

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I’ve got the following model, and some data, I’m trying to get a posterior over the infection probability for vaxxed and unvaxxed in my simulated dataset: @model function vaxxdecision(data) pv ~ Beta(1,100) pu…

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## [Question on the behavior of dot notation](https://discourse.julialang.org/t/question-on-the-behavior-of-dot-notation/72603)

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**Author:** [@yucho147](https://discourse.julialang.org/u/yucho147)\
**Replies:** 2\
**Last updated:** [December 5, 2021, 10:33am UTC](https://discourse.julialang.org/t/question-on-the-behavior-of-dot-notation/72603 "2021-12-05T10:33:23Z")

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As the title suggests, I have a question about the behavior of dot notation. Background I am implementing the conjugate gradient method. I am trying to speed up the vector processing by using dot notation. The problem …

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## [Laplacian of shallow Flux neural network with complex weights](https://discourse.julialang.org/t/laplacian-of-shallow-flux-neural-network-with-complex-weights/72600)

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**Author:** [@Matematija](https://discourse.julialang.org/u/Matematija)\
**Replies:** 0\
**Last updated:** [December 5, 2021, 4:14am UTC](https://discourse.julialang.org/t/laplacian-of-shallow-flux-neural-network-with-complex-weights/72600 "2021-12-05T04:14:06Z")

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Hi all, I am trying to use Julia’s AD ecosystem to calculate what the title says - a Laplacian (trace of Hessian matrix) of a shallow (1 layer) Flux neural net. There are two twists to the story: I need all of the we…

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## [Removed dev Pkg before free (1.6 and 1.7)](https://discourse.julialang.org/t/removed-dev-pkg-before-free-1-6-and-1-7/72428)

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**Author:** [@jacob-roth](https://discourse.julialang.org/u/jacob-roth)\
**Replies:** 5\
**Last updated:** [December 4, 2021, 7:32pm UTC](https://discourse.julialang.org/t/removed-dev-pkg-before-free-1-6-and-1-7/72428 "2021-12-04T19:32:13Z")

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I added a package and then dev’ed it and then removed it before freeing it. Now I am getting an error that I can’t fix. I removed the registries directory and also downloaded julia 1.7 and started fresh, but I get the fo…

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## [Github-action-benchmark with Julia support](https://discourse.julialang.org/t/github-action-benchmark-with-julia-support/72589)

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**Author:** [@findmyway](https://discourse.julialang.org/u/findmyway)\
**Replies:** 0\
**Last updated:** [December 4, 2021, 7:52pm UTC](https://discourse.julialang.org/t/github-action-benchmark-with-julia-support/72589 "2021-12-04T19:52:31Z")

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Recently I added the Julia support to an interesting github action: https://github.com/benchmark-action/github-action-benchmark Hope it might be useful to some other package developers. You can find how to enable the wo…

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## [IJulia notebook, local Pkg activate, julia-1.7.0 FAILures](https://discourse.julialang.org/t/ijulia-notebook-local-pkg-activate-julia-1-7-0-failures/72588)

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**Author:** [@proudindiv](https://discourse.julialang.org/u/proudindiv)\
**Replies:** 3\
**Last updated:** [December 4, 2021, 7:40pm UTC](https://discourse.julialang.org/t/ijulia-notebook-local-pkg-activate-julia-1-7-0-failures/72588 "2021-12-04T19:40:21Z")

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Julia-1.7.0 works fine in command-line REPL after getting Pkgs installed and recompiled, but has lots of various failures when precompiling some packages with the exact same code in IJulia notebooks: (I’ve deleted and r…

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## [Why is the intersection of a polyhedra with itself not equal to itself?](https://discourse.julialang.org/t/why-is-the-intersection-of-a-polyhedra-with-itself-not-equal-to-itself/72585)

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**Author:** [@XLVII](https://discourse.julialang.org/u/XLVII)\
**Replies:** 7\
**Last updated:** [December 4, 2021, 7:38pm UTC](https://discourse.julialang.org/t/why-is-the-intersection-of-a-polyhedra-with-itself-not-equal-to-itself/72585 "2021-12-04T19:38:42Z")

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using Polyhedra import CDDLib lib = CDDLib.Library() P = polyhedron(vrep(Acolums,Is),lib) #(lines=Acolums , rays = Is) println(intersect(P,P) == P ) # it should be true but it gives false How can it be made to ret…

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## [OverflowContexts.jl - Fine control of integer overflow checking](https://discourse.julialang.org/t/overflowcontexts-jl-fine-control-of-integer-overflow-checking/72273)

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**Author:** [@BioTurboNick](https://discourse.julialang.org/u/BioTurboNick)\
**Replies:** 1\
**Last updated:** [December 4, 2021, 6:54pm UTC](https://discourse.julialang.org/t/overflowcontexts-jl-fine-control-of-integer-overflow-checking/72273 "2021-12-04T18:54:14Z")

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Spurred on by a new gripe on Slack about an overflowing integer math issue, I revisited my test package for trying to allow Julia to switch between checked an unchecked arithmetic. I realized it essentially already provi…

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## [Embedding Julia in Julia](https://discourse.julialang.org/t/embedding-julia-in-julia/72586)

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**Author:** [@Chris\_Green](https://discourse.julialang.org/u/Chris_Green)\
**Replies:** 4\
**Last updated:** [December 4, 2021, 6:07pm UTC](https://discourse.julialang.org/t/embedding-julia-in-julia/72586 "2021-12-04T18:07:09Z")

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Suppose you were writing a GUI tool for Julia, in Julia. For instance if you were making an IDE or notebook-type interface with a Qt or Vulkan-based GUI. In order to execute Julia code that the user wants you to run with…

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## [Sparse matrix assembly with bad timings](https://discourse.julialang.org/t/sparse-matrix-assembly-with-bad-timings/72584)

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**Author:** [@Bardo](https://discourse.julialang.org/u/Bardo)\
**Replies:** 2\
**Last updated:** [December 4, 2021, 5:52pm UTC](https://discourse.julialang.org/t/sparse-matrix-assembly-with-bad-timings/72584 "2021-12-04T17:52:43Z")

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Hi, I took the 2016 codes from Julia iFEM 2: Optimizing Stiffness Matrix Assembly and made some cosmetic changes to run them with Julia 1.7. Chris’ old timings were: tic; assemblingstandard(node,elem); toc; tic; assem…

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## [Makie: problem with line plots?](https://discourse.julialang.org/t/makie-problem-with-line-plots/72534)

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**Author:** [@nchisholm](https://discourse.julialang.org/u/nchisholm)\
**Replies:** 5\
**Last updated:** [December 4, 2021, 5:39pm UTC](https://discourse.julialang.org/t/makie-problem-with-line-plots/72534 "2021-12-04T17:39:04Z")

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I am encountering an issue with GLMakie where lines on plots are drawn incorrectly as shown below. Only tiny segments of the line appear. Strangely, the plot is rendered correctly the first time the plotting command is…

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## [1 is not a UInt](https://discourse.julialang.org/t/1-is-not-a-uint/72578)

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**Author:** [@dodoplus](https://discourse.julialang.org/u/dodoplus)\
**Replies:** 5\
**Last updated:** [December 4, 2021, 5:12pm UTC](https://discourse.julialang.org/t/1-is-not-a-uint/72578 "2021-12-04T17:12:48Z")

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Hi, As typeof(1) == Int64, we have 1 isa UInt == false However, this makes it difficult to pass a default value: f(x::UInt = 1) = 2 f() # MethodError: no method matching f(::Int64) Sure, I can define: f(x::UInt = U…

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## [Derivative in Symbolics.jl becomes zero?](https://discourse.julialang.org/t/derivative-in-symbolics-jl-becomes-zero/72491)

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**Author:** [@Ahmed\_Salih](https://discourse.julialang.org/u/Ahmed_Salih)\
**Replies:** 2\
**Last updated:** [December 4, 2021, 2:47pm UTC](https://discourse.julialang.org/t/derivative-in-symbolics-jl-becomes-zero/72491 "2021-12-04T14:47:28Z")

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Hi! I am playing around with Julia 1.7.0. I am using this piece of code: using Symbolics @variables x z1(x) = x z2 = x Dx = Differential(x) expand\_derivatives(Dx(z1)) #Gives 0 expand\_derivatives(Dx(z2)) #Gi…

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## [Force keyword argument input with keyword name for a function](https://discourse.julialang.org/t/force-keyword-argument-input-with-keyword-name-for-a-function/72575)

<div class="topic-metadata">

**Author:** [@AtsushiSakai](https://discourse.julialang.org/u/AtsushiSakai)\
**Replies:** 1\
**Last updated:** [December 4, 2021, 1:26pm UTC](https://discourse.julialang.org/t/force-keyword-argument-input-with-keyword-name-for-a-function/72575 "2021-12-04T13:26:01Z")

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In python, we can force keyword argument input with keyword name for a function using “\*” like: In \[3\]: def f(a, b, c=0, d=1): ...: pass ...: In \[4\]: f(1, 2, 3, 4) In \[5\]: f(1, 2, c=3, d=4) In \[6\]: def f(a,…

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## [Plot @layout adjust width of grid](https://discourse.julialang.org/t/plot-layout-adjust-width-of-grid/72527)

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**Author:** [@evolbio](https://discourse.julialang.org/u/evolbio)\
**Replies:** 5\
**Last updated:** [December 4, 2021, 11:33am UTC](https://discourse.julialang.org/t/plot-layout-adjust-width-of-grid/72527 "2021-12-04T11:33:27Z")

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My goal is a layout like: @layout \[grid(4,2) \[b; c{0.166h}; d{0.166h}; e{0.166h}\]\] which is a 4 x 2 grid on the left and a stack of 4 plots on the right. However, I want the left 4 x 2 grid to be 1/3 of the total width…

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## [Forward- and reverse-mode AD comparisons with JAX](https://discourse.julialang.org/t/forward-and-reverse-mode-ad-comparisons-with-jax/72379)

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**Author:** [@wil-j-wil](https://discourse.julialang.org/u/wil-j-wil)\
**Replies:** 7\
**Last updated:** [December 4, 2021, 11:16am UTC](https://discourse.julialang.org/t/forward-and-reverse-mode-ad-comparisons-with-jax/72379 "2021-12-04T11:16:53Z")

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I have been attempting to compute the gradients of a covariance function (kernel) in Julia. I was initially using Zygote, incorrectly since forward-mode is much better suited to my task. However this resulted in some int…

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## [Segfaults on Julia 1.7 Apple M1](https://discourse.julialang.org/t/segfaults-on-julia-1-7-apple-m1/72566)

<div class="topic-metadata">

**Author:** [@essenciary](https://discourse.julialang.org/u/essenciary)\
**Replies:** 2\
**Last updated:** [December 4, 2021, 10:43am UTC](https://discourse.julialang.org/t/segfaults-on-julia-1-7-apple-m1/72566 "2021-12-04T10:43:22Z")

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Julia 1.7 is extremely unstable for me, to the point of being unusable. Getting segfaults in some apps about 50% of the times. It’s been like that since pre-release days but I hoped the issue would go away in the final r…

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## [Array slice \[1:\<variable\]](https://discourse.julialang.org/t/array-slice-1-variable/72567)

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**Author:** [@46do14](https://discourse.julialang.org/u/46do14)\
**Replies:** 2\
**Last updated:** [December 4, 2021, 9:46am UTC](https://discourse.julialang.org/t/array-slice-1-variable/72567 "2021-12-04T09:46:23Z")

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Hello I am new to Julia Language aund I am struggling with following problem: In my data array are empty elements and I am able to find the indices of these elements \> indices = findall(x → x == “”, data) Next I want…

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