# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1569

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

**Page:** 1570

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## [Error in ploting a surface with Plots+plotlyjs()](https://discourse.julialang.org/t/error-in-ploting-a-surface-with-plots-plotlyjs/50373)

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**Author:** [@tiago](https://discourse.julialang.org/u/tiago)\
**Replies:** 2\
**Last updated:** [November 18, 2020, 12:48pm UTC](https://discourse.julialang.org/t/error-in-ploting-a-surface-with-plots-plotlyjs/50373 "2020-11-18T12:48:40Z")

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Hello, I’m having troubles to plot a surface using the plotlyjs() of the package Plots.jl. Let me show you a simple example of what I’m getting: plotlyjs() x=1:10 y=1:10 z=rand(10,10) plot(x,y,z,st=:surface,fill=true)…

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## [Gpu\_rand inside @cuda](https://discourse.julialang.org/t/gpu-rand-inside-cuda/50322)

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**Author:** [@dgatey](https://discourse.julialang.org/u/dgatey)\
**Replies:** 2\
**Last updated:** [November 18, 2020, 10:41am UTC](https://discourse.julialang.org/t/gpu-rand-inside-cuda/50322 "2020-11-18T10:41:14Z")

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Hey Everyone, I’ve managed to use gpu\_rand via gpu\_call but was wondering if it is possible to use gpu\_rand via @cuda as I’m currently using a 2D block. The @cuda function call only accepts bit types so I’m struggling …

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## [Reload a module imported with Using/import in main](https://discourse.julialang.org/t/reload-a-module-imported-with-using-import-in-main/50335)

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**Author:** [@lorrp1](https://discourse.julialang.org/u/lorrp1)\
**Replies:** 1\
**Last updated:** [November 18, 2020, 10:07am UTC](https://discourse.julialang.org/t/reload-a-module-imported-with-using-import-in-main/50335 "2020-11-18T10:07:15Z")

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Hello, i have a .jl in which i have created a module. module name end import Main.name or using Main. in the same file of the module created im importing/using them, but modifying the module and then reloading with …

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## [Julia on Apple M1?](https://discourse.julialang.org/t/julia-on-apple-m1/50366)

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**Author:** [@robertfeldt](https://discourse.julialang.org/u/robertfeldt)\
**Replies:** 2\
**Last updated:** [November 18, 2020, 9:32am UTC](https://discourse.julialang.org/t/julia-on-apple-m1/50366 "2020-11-18T09:32:59Z")

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Has anyone tried/managed to compile Julia on one of the new Macs with the ARM Apple M1 CPU? I will get my MacBook in circa 2 weeks and the first thing to get up and running is Julia, if possible. If anyone already has ex…

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## [How to use a range of DateTime as Dict keys](https://discourse.julialang.org/t/how-to-use-a-range-of-datetime-as-dict-keys/26688)

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**Author:** [@farasa](https://discourse.julialang.org/u/farasa)\
**Replies:** 2\
**Last updated:** [November 18, 2020, 9:10am UTC](https://discourse.julialang.org/t/how-to-use-a-range-of-datetime-as-dict-keys/26688 "2020-11-18T09:10:22Z")

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Hello, Is there any way to to do this: P1= DateTime(2015,08,1,12,00,00) P2=DateTime(2015,08,1,20,00,00) range(P1,P2) ==\> 3 . . So then I would like to check time periods if they are between P1 and P2?

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## [Arpack and MKL](https://discourse.julialang.org/t/arpack-and-mkl/50291)

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**Author:** [@Jonas](https://discourse.julialang.org/u/Jonas)\
**Replies:** 1\
**Last updated:** [November 18, 2020, 9:07am UTC](https://discourse.julialang.org/t/arpack-and-mkl/50291 "2020-11-18T09:07:20Z")

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Hello everyone, I wrote some code to calculate the first n eigenvalues and eigenvectors of a generalized eigenvalue problem over a two-dimensional mesh. For this I used the function eigs() of the package Arpack. Since t…

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## [Julia DifferentialEquations: increase maxiter](https://discourse.julialang.org/t/julia-differentialequations-increase-maxiter/50318)

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**Author:** [@Luigi\_Marongiu](https://discourse.julialang.org/u/Luigi_Marongiu)\
**Replies:** 6\
**Last updated:** [November 18, 2020, 7:57am UTC](https://discourse.julialang.org/t/julia-differentialequations-increase-maxiter/50318 "2020-11-18T07:57:54Z")

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Hello, I have set an ODEProblem object, but the procedure is stopped (although I still get t a solution) because a higher maxiters is needed. How can I check what is the default value and what is the syntax to increase…

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## [Julia DifferentialEquations: add delay into ODE](https://discourse.julialang.org/t/julia-differentialequations-add-delay-into-ode/50337)

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**Author:** [@Luigi\_Marongiu](https://discourse.julialang.org/u/Luigi_Marongiu)\
**Replies:** 3\
**Last updated:** [November 18, 2020, 7:03am UTC](https://discourse.julialang.org/t/julia-differentialequations-add-delay-into-ode/50337 "2020-11-18T07:03:01Z")

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Hello, I have a set of ODE to model the growth of bacteria nad phages: function multiInfect!(du, u, p, t) μ, ν, κ, φ, ψ, ω, β, Β, ρ, τ, η, Η = p #= du\[1\] = resident susceptible du\[2\] = resident infected…

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## [Some structures cannot be differentiated automatically?](https://discourse.julialang.org/t/some-structures-cannot-be-differentiated-automatically/50358)

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**Author:** [@yeruoforever](https://discourse.julialang.org/u/yeruoforever)\
**Replies:** 0\
**Last updated:** [November 18, 2020, 5:46am UTC](https://discourse.julialang.org/t/some-structures-cannot-be-differentiated-automatically/50358 "2020-11-18T05:46:43Z")

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Dear All, I am a student learning neural network. I implemented a small graph neural network model using Flux and MetaGraphs, but there was a problem that puzzled me. I posted the problematic code below, hope my friends…

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## [Slurm cpus vs tasks in Distributed](https://discourse.julialang.org/t/slurm-cpus-vs-tasks-in-distributed/50357)

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**Author:** [@mkarikom](https://discourse.julialang.org/u/mkarikom)\
**Replies:** 0\
**Last updated:** [November 18, 2020, 5:39am UTC](https://discourse.julialang.org/t/slurm-cpus-vs-tasks-in-distributed/50357 "2020-11-18T05:39:18Z")

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Given that Slurm tasks map to workers in Distributed, it seems like there is actually no representation of Slurm “cpus” in the sbatch “–cpus-per-task” sense. Is this correct?

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## [\[ANN\] PopGen.jl v0.4.0 and PopGenSims.jl v0.0.2](https://discourse.julialang.org/t/ann-popgen-jl-v0-4-0-and-popgensims-jl-v0-0-2/50316)

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**Author:** [@pdimens](https://discourse.julialang.org/u/pdimens)\
**Replies:** 4\
**Last updated:** [November 17, 2020, 9:47pm UTC](https://discourse.julialang.org/t/ann-popgen-jl-v0-4-0-and-popgensims-jl-v0-0-2/50316 "2020-11-17T21:47:05Z")

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Hello all, I’m thrilled to announce the next release of PopGen.jl v0.4.0 (although incorrectly versioned in the release, oops). Internal tweaks removing CategoricalArrays in favor of PooledArrays cleaning up and adding…

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## [Environment variable for julia --procs](https://discourse.julialang.org/t/environment-variable-for-julia-procs/50356)

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**Author:** [@jzr](https://discourse.julialang.org/u/jzr)\
**Replies:** 0\
**Last updated:** [November 18, 2020, 5:12am UTC](https://discourse.julialang.org/t/environment-variable-for-julia-procs/50356 "2020-11-18T05:12:16Z")

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For --threads there is JULIA\_NUM\_THREADS. Is there an environment variable for --procs?

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## [Not show plot in juno ide](https://discourse.julialang.org/t/not-show-plot-in-juno-ide/50354)

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**Author:** [@Ravinder\_Ram](https://discourse.julialang.org/u/Ravinder_Ram)\
**Replies:** 0\
**Last updated:** [November 18, 2020, 3:56am UTC](https://discourse.julialang.org/t/not-show-plot-in-juno-ide/50354 "2020-11-18T03:56:31Z")

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when i use gadfly… use plot() nothing is shown in plot tab in juno ide what should i do?

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## [Specify alternative ffmpeg](https://discourse.julialang.org/t/specify-alternative-ffmpeg/50353)

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**Author:** [@jzr](https://discourse.julialang.org/u/jzr)\
**Replies:** 0\
**Last updated:** [November 18, 2020, 3:42am UTC](https://discourse.julialang.org/t/specify-alternative-ffmpeg/50353 "2020-11-18T03:42:49Z")

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FFMPEG.jl uses an included artifact for ffmpeg, but I want to use a different one. How can I specify an alternative ffmpeg?

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## [JuMP model Polyhedron](https://discourse.julialang.org/t/jump-model-polyhedron/50108)

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**Author:** [@JohnZ](https://discourse.julialang.org/u/JohnZ)\
**Replies:** 11\
**Last updated:** [November 18, 2020, 1:33am UTC](https://discourse.julialang.org/t/jump-model-polyhedron/50108 "2020-11-18T01:33:34Z")

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Hi, I am trying to plot the feasible set of a JuMP model as a 3D figure. I have used the syntax provided in Polyhedra.jl documentation to create a polyhedron: Optimization · Polyhedra A simple example is given below: …

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## [Heart given by mistake cannot be erased?](https://discourse.julialang.org/t/heart-given-by-mistake-cannot-be-erased/29852)

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**Author:** [@PetrKryslUCSD](https://discourse.julialang.org/u/PetrKryslUCSD)\
**Replies:** 5\
**Last updated:** [November 18, 2020, 1:27am UTC](https://discourse.julialang.org/t/heart-given-by-mistake-cannot-be-erased/29852 "2020-11-18T01:27:41Z")

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My mouse fell and the button press put a :heartbeat: on Now I can’t “unlike” it. Why is it just in this post (it works elsewhere), and can I undo it? Thanks @vchuravy

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## [How to get better performance from NUTS in Turing?](https://discourse.julialang.org/t/how-to-get-better-performance-from-nuts-in-turing/50349)

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**Author:** [@mkarikom](https://discourse.julialang.org/u/mkarikom)\
**Replies:** 0\
**Last updated:** [November 18, 2020, 12:54am UTC](https://discourse.julialang.org/t/how-to-get-better-performance-from-nuts-in-turing/50349 "2020-11-18T00:54:32Z")

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I’m wondering if anyone has further performance tips to speed this up? This MWE is an attempt to use NUTS on data that is similar in size to my actual use case, following the model introduced in this post, but no longer…

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## [DBnomics - World Economic Database](https://discourse.julialang.org/t/dbnomics-world-economic-database/50242)

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**Author:** [@tlorans](https://discourse.julialang.org/u/tlorans)\
**Replies:** 1\
**Last updated:** [November 18, 2020, 12:28am UTC](https://discourse.julialang.org/t/dbnomics-world-economic-database/50242 "2020-11-18T00:28:32Z")

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Hello everybody, This is my first post in this forum. :slight\_smile: I would like to point out the existence of a Julia version of the DBnomics API. The DBnomics project is led by French academics and aims to concatena…

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## [Substituting state and parameter values in jacobian of DifferentialEquations.jl system using ModelingToolkit](https://discourse.julialang.org/t/substituting-state-and-parameter-values-in-jacobian-of-differentialequations-jl-system-using-modelingtoolkit/50264)

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**Author:** [@claudio20497](https://discourse.julialang.org/u/claudio20497)\
**Replies:** 2\
**Last updated:** [November 17, 2020, 11:48pm UTC](https://discourse.julialang.org/t/substituting-state-and-parameter-values-in-jacobian-of-differentialequations-jl-system-using-modelingtoolkit/50264 "2020-11-17T23:48:31Z")

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So I would like to explicitly evaluate the R\_0 of an epidemiological model written in DifferentialEquations.jl using ModelingToolkit.jl. Here is a simple SIRD model: using DifferentialEquations, ModelingToolkit # Mode…

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## [Float64 error when using ForwardDiff.gradient for nested functions](https://discourse.julialang.org/t/float64-error-when-using-forwarddiff-gradient-for-nested-functions/50343)

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**Author:** [@yips](https://discourse.julialang.org/u/yips)\
**Replies:** 0\
**Last updated:** [November 17, 2020, 11:22pm UTC](https://discourse.julialang.org/t/float64-error-when-using-forwarddiff-gradient-for-nested-functions/50343 "2020-11-17T23:22:54Z")

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I am trying to use ForwardDiff.gradient find the gradient of the following function: function loss\_test(x::Array{T,2},SecreteFuncs,pInf::Array{T,2},cmat::Array{T,2}) where {T \<: Real} cmat\_sol = Findcss(x,SecreteFuncs…

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## [When does package code get loaded in a module](https://discourse.julialang.org/t/when-does-package-code-get-loaded-in-a-module/50253)

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**Author:** [@louisponet](https://discourse.julialang.org/u/louisponet)\
**Replies:** 16\
**Last updated:** [November 17, 2020, 10:17pm UTC](https://discourse.julialang.org/t/when-does-package-code-get-loaded-in-a-module/50253 "2020-11-17T22:17:54Z")

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Hi all, Since my last question world age problem when does a generated function get generated did not get any answers, maybe because it was too specific, I’ll try again here. I think my issue boils down to this questio…

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## [TableOperations.select](https://discourse.julialang.org/t/tableoperations-select/50334)

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**Author:** [@djholiver](https://discourse.julialang.org/u/djholiver)\
**Replies:** 0\
**Last updated:** [November 17, 2020, 9:43pm UTC](https://discourse.julialang.org/t/tableoperations-select/50334 "2020-11-17T21:43:20Z")

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Hi, I have been making use of the Arrow.jl library and am currently experiencing difficulty in attempting to obtain a subset of columns from the original (Arrow) table and writing to another, via the TableOperations.sel…

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## [Using addprocs and pmap inside a function](https://discourse.julialang.org/t/using-addprocs-and-pmap-inside-a-function/50329)

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**Author:** [@sdgu](https://discourse.julialang.org/u/sdgu)\
**Replies:** 0\
**Last updated:** [November 17, 2020, 8:53pm UTC](https://discourse.julialang.org/t/using-addprocs-and-pmap-inside-a-function/50329 "2020-11-17T20:53:07Z")

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Heya, Here’s a code file ex1.jl that does what it’s supposed to when I run julia ex1.jl: module MWE export gen\_complicated\_thing, do\_para function complicated\_helper() return Dict() end function gen\_complicated\_t…

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## [Optimization of Curves](https://discourse.julialang.org/t/optimization-of-curves/50312)

<div class="topic-metadata">

**Author:** [@brett\_knoss](https://discourse.julialang.org/u/brett_knoss)\
**Replies:** 8\
**Last updated:** [November 17, 2020, 8:50pm UTC](https://discourse.julialang.org/t/optimization-of-curves/50312 "2020-11-17T20:50:55Z")

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What is a good option for finding the x value of a tangent point of a curve (such as matching price and value), or finding the minimum or maximum of a curve.

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## [Interface for subtypes of Core.Real](https://discourse.julialang.org/t/interface-for-subtypes-of-core-real/50299)

<div class="topic-metadata">

**Author:** [@josuagrw](https://discourse.julialang.org/u/josuagrw)\
**Replies:** 6\
**Last updated:** [November 17, 2020, 8:34pm UTC](https://discourse.julialang.org/t/interface-for-subtypes-of-core-real/50299 "2020-11-17T20:34:28Z")

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Many packages subtype Core.Real to take advantage of the generic methods in Base and interface with third-party packages. However, while similar supertypes like Base.Array have their interface defined in the Julia manual…

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## [How to add a Feature in Julia Lang](https://discourse.julialang.org/t/how-to-add-a-feature-in-julia-lang/50325)

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**Author:** [@Impressium](https://discourse.julialang.org/u/Impressium)\
**Replies:** 7\
**Last updated:** [November 17, 2020, 8:33pm UTC](https://discourse.julialang.org/t/how-to-add-a-feature-in-julia-lang/50325 "2020-11-17T20:33:04Z")

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I would like to use Sets like this: julia\> Set(1,2,3) Set{Int64} with 3 elements: 2 3 1 I want to add one overload. julia\> Set(args::T...) where T = Set(args) Set julia\> Set(args::Any...) = Set(args) Set How w…

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## [Deleting constraints strange behavior](https://discourse.julialang.org/t/deleting-constraints-strange-behavior/50324)

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**Author:** [@J\_Friedman](https://discourse.julialang.org/u/J_Friedman)\
**Replies:** 0\
**Last updated:** [November 17, 2020, 7:59pm UTC](https://discourse.julialang.org/t/deleting-constraints-strange-behavior/50324 "2020-11-17T19:59:03Z")

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Why is it that when one deletes an object from a model, it keeps the variable attached? @constraint(model, con, 2x \<= 1) delete(model, con) @constraint(model, con, 2x \<= 1) ERROR: An object of name con is already att…

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## [Matrix multiplication](https://discourse.julialang.org/t/matrix-multiplication/50293)

<div class="topic-metadata">

**Author:** [@nhavt](https://discourse.julialang.org/u/nhavt)\
**Replies:** 6\
**Last updated:** [November 17, 2020, 7:45pm UTC](https://discourse.julialang.org/t/matrix-multiplication/50293 "2020-11-17T19:45:22Z")

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Hi there, I need to perform many matrix multiplications as follows. Here I proposed two functions (f1 and f2). I am wondering whether we could improve the speed of the function f2 further? Thanks in advance! using Line…

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## [Variable which disappear in a for](https://discourse.julialang.org/t/variable-which-disappear-in-a-for/50304)

<div class="topic-metadata">

**Author:** [@Dailysight](https://discourse.julialang.org/u/Dailysight)\
**Replies:** 6\
**Last updated:** [November 17, 2020, 7:32pm UTC](https://discourse.julialang.org/t/variable-which-disappear-in-a-for/50304 "2020-11-17T19:32:17Z")

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Hey everyone ! First of all, i would like to thank everyone of this community for the help you give to beginners like me. Actually, i have a problem about a variable which disappear when i enter a for loop. Does anyon…

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## [2D Structured Mesh Generator](https://discourse.julialang.org/t/2d-structured-mesh-generator/50310)

<div class="topic-metadata">

**Author:** [@Obtuya7](https://discourse.julialang.org/u/Obtuya7)\
**Replies:** 1\
**Last updated:** [November 17, 2020, 6:49pm UTC](https://discourse.julialang.org/t/2d-structured-mesh-generator/50310 "2020-11-17T18:49:05Z")

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This is more of a programming question than a Julia question… I am trying to create a 2D structured mesh generator for an arbitrary domain shape of square elements. There are probably packages available to accomplish thi…

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