# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1418

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

**Page:** 1419

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## [Julia 1.6: using curl behind proxy for artifacts downloads on windows](https://discourse.julialang.org/t/julia-1-6-using-curl-behind-proxy-for-artifacts-downloads-on-windows/58029)

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**Author:** [@lrnv](https://discourse.julialang.org/u/lrnv)\
**Replies:** 2\
**Last updated:** [April 20, 2021, 8:04pm UTC](https://discourse.julialang.org/t/julia-1-6-using-curl-behind-proxy-for-artifacts-downloads-on-windows/58029 "2021-04-20T20:04:37Z")

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Hey, I just removed my 1.5.3 julia to install the new 1.6 on a window machine behind a proxy. For some reasons Pkg cannot download artifacts anymore: (@v1.6) pkg\> add Distributions Updating registry at \`C:\\Users\\u0…

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## [Bounding Correlation Coefficients for Multiple Problems with JuMP](https://discourse.julialang.org/t/bounding-correlation-coefficients-for-multiple-problems-with-jump/59690)

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**Author:** [@phantom](https://discourse.julialang.org/u/phantom)\
**Replies:** 1\
**Last updated:** [April 20, 2021, 7:57pm UTC](https://discourse.julialang.org/t/bounding-correlation-coefficients-for-multiple-problems-with-jump/59690 "2021-04-20T19:57:56Z")

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Hi this is a very elementary questions but I’m still trying to understand the code from this example for the correlation problem. The example I am using is the bounding correlation coefficients problem from “Convex Opti…

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## [Help: policy iteration](https://discourse.julialang.org/t/help-policy-iteration/59685)

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**Author:** [@ZettEff](https://discourse.julialang.org/u/ZettEff)\
**Replies:** 0\
**Last updated:** [April 20, 2021, 6:29pm UTC](https://discourse.julialang.org/t/help-policy-iteration/59685 "2021-04-20T18:29:36Z")

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I am struggling with the implementation of an (toy) optimization problem using dynamic programming. Although this is not a pure Julia question, I hope someone can help me with this. Being new to dynamic programming / re…

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## [Gtk: How do I resize a window programmatically?](https://discourse.julialang.org/t/gtk-how-do-i-resize-a-window-programmatically/59684)

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**Author:** [@johntrinder](https://discourse.julialang.org/u/johntrinder)\
**Replies:** 2\
**Last updated:** [April 20, 2021, 7:50pm UTC](https://discourse.julialang.org/t/gtk-how-do-i-resize-a-window-programmatically/59684 "2021-04-20T19:50:57Z")

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In Julia Gtk, how do I resize a window or widget/container programmatically?

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## [Understanding allocations when collapsing function arugments](https://discourse.julialang.org/t/understanding-allocations-when-collapsing-function-arugments/59668)

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**Author:** [@bashonubuntu](https://discourse.julialang.org/u/bashonubuntu)\
**Replies:** 15\
**Last updated:** [April 20, 2021, 7:24pm UTC](https://discourse.julialang.org/t/understanding-allocations-when-collapsing-function-arugments/59668 "2021-04-20T19:24:25Z")

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Hi everyone, I was hoping I could be helped in understanding the following concept. The code is a bit too long to provide a clean MWE, but I am trying to understanding the following: julia\> @btime integrand\_B1\_new($y,$…

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## [Quiver plot (Plots.pyplot) with different colors depending on the length of the arrow](https://discourse.julialang.org/t/quiver-plot-plots-pyplot-with-different-colors-depending-on-the-length-of-the-arrow/59577)

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**Author:** [@hardy](https://discourse.julialang.org/u/hardy)\
**Replies:** 11\
**Last updated:** [April 20, 2021, 7:01pm UTC](https://discourse.julialang.org/t/quiver-plot-plots-pyplot-with-different-colors-depending-on-the-length-of-the-arrow/59577 "2021-04-20T19:01:43Z")

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Hello, I am new to Julia and tried to plot the gradient field of a loss function. I can get the lengths of the arrows by norm(dx, dy). But I don’t know how to convert a vector of values (lengths) into a vector of colors…

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## [Not sure to understand how matrices are displayed](https://discourse.julialang.org/t/not-sure-to-understand-how-matrices-are-displayed/59371)

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**Author:** [@Lecrapouille](https://discourse.julialang.org/u/Lecrapouille)\
**Replies:** 8\
**Last updated:** [April 20, 2021, 6:57pm UTC](https://discourse.julialang.org/t/not-sure-to-understand-how-matrices-are-displayed/59371 "2021-04-20T18:57:08Z")

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Hi ! At least, since Julia 1.3, still now with Julia 1.6 I did not know how to fix misaligned simple matrices. julia\> A=\[45 "m" 6; 4.5 5 't'\] 2×3 Matrix{Any}: 45 "m" 6 4.5 5 't' This is an issue for my p…

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## [JuliaFEM cannot be precompiled](https://discourse.julialang.org/t/juliafem-cannot-be-precompiled/47119)

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**Author:** [@Alex2](https://discourse.julialang.org/u/Alex2)\
**Replies:** 6\
**Last updated:** [April 20, 2021, 6:57pm UTC](https://discourse.julialang.org/t/juliafem-cannot-be-precompiled/47119 "2021-04-20T18:57:01Z")

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Hi julia experts, I installed and built JuliaFEM right after installing Julia1.5 but when I type ‘using JuliaFEM’, I got error: ERROR:LoadError:LoadError:Evaluation into the closed module ‘Calculus’ breaks incremental…

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## [Mentor at a GPU Hackathon](https://discourse.julialang.org/t/mentor-at-a-gpu-hackathon/59688)

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**Author:** [@jlevites](https://discourse.julialang.org/u/jlevites)\
**Replies:** 0\
**Last updated:** [April 20, 2021, 6:50pm UTC](https://discourse.julialang.org/t/mentor-at-a-gpu-hackathon/59688 "2021-04-20T18:50:02Z")

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Hi Everyone! We are hosting a GPU Hackathon in Princeton and looks like 2 teams will be using Julia for their codes. The dates are June 2, 9,10,11. We are looking for mentors to support the teams for the duration of the …

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## [Custom hash function in dict is very slow?](https://discourse.julialang.org/t/custom-hash-function-in-dict-is-very-slow/59683)

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**Author:** [@pjentsch0](https://discourse.julialang.org/u/pjentsch0)\
**Replies:** 3\
**Last updated:** [April 20, 2021, 6:44pm UTC](https://discourse.julialang.org/t/custom-hash-function-in-dict-is-very-slow/59683 "2021-04-20T18:44:57Z")

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why is using a custom hash function in a dict so slow? using BenchmarkTools import Base.hash,Base.isequal rtuple() = (trunc(Int,rand()\*10\_000),trunc(Int,rand()\*10\_000)) #make random tuple in \[0,10\_000) function Base.ha…

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## ["Broken" link in main Julia Discourse page](https://discourse.julialang.org/t/broken-link-in-main-julia-discourse-page/59682)

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**Author:** [@mocalvao](https://discourse.julialang.org/u/mocalvao)\
**Replies:** 1\
**Last updated:** [April 20, 2021, 5:42pm UTC](https://discourse.julialang.org/t/broken-link-in-main-julia-discourse-page/59682 "2021-04-20T17:42:39Z")

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I would like to call attention to whoever is in charge of the maintenance of this Julia discourse, to the fact that the link, in its main page, to https://discourse.julialang.org/c/user/first-steps does not work or rathe…

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## [How can I clear the REPL's scrollback buffer?](https://discourse.julialang.org/t/how-can-i-clear-the-repls-scrollback-buffer/45049)

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**Author:** [@NightMachinary](https://discourse.julialang.org/u/NightMachinary)\
**Replies:** 6\
**Last updated:** [April 20, 2021, 5:06pm UTC](https://discourse.julialang.org/t/how-can-i-clear-the-repls-scrollback-buffer/45049 "2021-04-20T17:06:50Z")

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I like to clear the REPL’s scrollback buffer programmatically. This helps me when running functions with long outputs, as I can easily use the scrollbar to jump to anywhere in the logs created by that function. Using CTR…

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## [Performance closures with changing value of closed over variables](https://discourse.julialang.org/t/performance-closures-with-changing-value-of-closed-over-variables/59671)

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**Author:** [@lmiq](https://discourse.julialang.org/u/lmiq)\
**Replies:** 1\
**Last updated:** [April 20, 2021, 4:58pm UTC](https://discourse.julialang.org/t/performance-closures-with-changing-value-of-closed-over-variables/59671 "2021-04-20T16:58:36Z")

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Similar things have been discussed in other threads, but this particular example was surprising to me: julia\> function main(x) g(x,y) = x + y f(x,inner\_g) = inner\_g(x) y = 1 f(x, x -\> …

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## [Libnetcdf not defined](https://discourse.julialang.org/t/libnetcdf-not-defined/59039)

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**Author:** [@mixstam1453](https://discourse.julialang.org/u/mixstam1453)\
**Replies:** 6\
**Last updated:** [April 20, 2021, 4:45pm UTC](https://discourse.julialang.org/t/libnetcdf-not-defined/59039 "2021-04-20T16:45:52Z")

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Hello everybody, I get “libnetcdf not defined” when i try to open a ncfile, using NCDatasets & NetCDF. I use Debian Buster, 32 bit. Julia 1.5.3. Have you any idea to solve it ? I already did this " using Pkg pkg"ad…

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## [Getting to 1.0 -- How can we get packages to "make that tag"?](https://discourse.julialang.org/t/getting-to-1-0-how-can-we-get-packages-to-make-that-tag/59608)

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**Author:** [@cce](https://discourse.julialang.org/u/cce)\
**Replies:** 17\
**Last updated:** [April 20, 2021, 4:38pm UTC](https://discourse.julialang.org/t/getting-to-1-0-how-can-we-get-packages-to-make-that-tag/59608 "2021-04-20T16:38:15Z")

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So many core packages in the Julia community, such as DataFrames are still pre-1.0 well after they have become ubiquitous. This causes a bit of confusion. Is the lack of a 1.0 a suggestion to users that they shouldn’t d…

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## [Cannot load image and do fftshift inside the same function](https://discourse.julialang.org/t/cannot-load-image-and-do-fftshift-inside-the-same-function/59663)

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**Author:** [@alberttxu](https://discourse.julialang.org/u/alberttxu)\
**Replies:** 2\
**Last updated:** [April 20, 2021, 4:12pm UTC](https://discourse.julialang.org/t/cannot-load-image-and-do-fftshift-inside-the-same-function/59663 "2021-04-20T16:12:56Z")

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Hi all, I encountered an error while trying to load an image and run an fftshift inside a function. My minimal working example is using TestImages, FFTW function f() img = testimage("mandrill") fftshift(img) e…

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## [What would it take to bring this Julia 0.6 package to Julia 1.6?](https://discourse.julialang.org/t/what-would-it-take-to-bring-this-julia-0-6-package-to-julia-1-6/59652)

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**Author:** [@lrnv](https://discourse.julialang.org/u/lrnv)\
**Replies:** 31\
**Last updated:** [April 20, 2021, 3:52pm UTC](https://discourse.julialang.org/t/what-would-it-take-to-bring-this-julia-0-6-package-to-julia-1-6/59652 "2021-04-20T15:52:19Z")

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Hi, I found myself in a position where i need to solve a fully constraint lasso. There is a package there : GitHub - Hua-Zhou/ConstrainedLasso.jl: Algorithms for fit constrained lasso that does exactly what i need, but …

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## [Adventure is SQL and Graph Theory (part 1)](https://discourse.julialang.org/t/adventure-is-sql-and-graph-theory-part-1/59665)

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**Author:** [@AlexanderChen](https://discourse.julialang.org/u/AlexanderChen)\
**Replies:** 1\
**Last updated:** [April 20, 2021, 3:29pm UTC](https://discourse.julialang.org/t/adventure-is-sql-and-graph-theory-part-1/59665 "2021-04-20T15:29:17Z")

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Graph theory and SQL I have recently finish a project on the intersection of Graph Theory and SQL. And I would like to share my experience for others. Research question: find a valid usecase to combine traditional SQL…

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## [How to create a multilayer perceptron using Flux](https://discourse.julialang.org/t/how-to-create-a-multilayer-perceptron-using-flux/59673)

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**Author:** [@Antonino\_Gandolfo](https://discourse.julialang.org/u/Antonino_Gandolfo)\
**Replies:** 0\
**Last updated:** [April 20, 2021, 3:27pm UTC](https://discourse.julialang.org/t/how-to-create-a-multilayer-perceptron-using-flux/59673 "2021-04-20T15:27:23Z")

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Hi I’m new with Julia and I have some problems with the creation of a multilayer perceptron. I’ve tried following some guides about this topic but I couldn’t figure it out the solution. My question is: How can i add a…

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## [Concatenate Generators](https://discourse.julialang.org/t/concatenate-generators/59653)

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**Author:** [@etienne\_dg](https://discourse.julialang.org/u/etienne_dg)\
**Replies:** 18\
**Last updated:** [April 20, 2021, 3:01pm UTC](https://discourse.julialang.org/t/concatenate-generators/59653 "2021-04-20T15:01:00Z")

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Hi, I try to initialize a vector in two parts, for example, a vector with fifty 0’s then fifty 1’s. I can create it in a loop, but it is not very concise: function foo1() a = Array{Int64}(undef, 100) for i in …

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## [Describing the state of a Julia program](https://discourse.julialang.org/t/describing-the-state-of-a-julia-program/59610)

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**Author:** [@jzr](https://discourse.julialang.org/u/jzr)\
**Replies:** 5\
**Last updated:** [April 20, 2021, 2:53pm UTC](https://discourse.julialang.org/t/describing-the-state-of-a-julia-program/59610 "2021-04-20T14:53:18Z")

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In this GitHub comment @StefanKarpinski wrote I’ve often wanted the ability to snapshot a running program and be able to restart the snapshot – multi-shot continuations but for programs, if you will – but it seems to b…

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## [Order matters in the conflicts with imported names](https://discourse.julialang.org/t/order-matters-in-the-conflicts-with-imported-names/59628)

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**Author:** [@heliosdrm](https://discourse.julialang.org/u/heliosdrm)\
**Replies:** 2\
**Last updated:** [April 20, 2021, 2:37pm UTC](https://discourse.julialang.org/t/order-matters-in-the-conflicts-with-imported-names/59628 "2021-04-20T14:37:43Z")

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I have been struggling to understand the nuances of what happens when there are conflicts with names imported from other modules. I eventually found by myself a consistent explanation for import Foo: bar. If I’m not mis…

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## [Generating "INSERT INTO" SQL statement](https://discourse.julialang.org/t/generating-insert-into-sql-statement/59106)

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**Author:** [@Laco\_Kovac](https://discourse.julialang.org/u/Laco_Kovac)\
**Replies:** 19\
**Last updated:** [April 20, 2021, 1:00pm UTC](https://discourse.julialang.org/t/generating-insert-into-sql-statement/59106 "2021-04-20T13:00:45Z")

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I have either LibPQ.Result or DataFrame as an input, and as output I need to generate SQL statement in the form: INSERT INTO table VALUES (v1,v2,v3), (v4,v5,v6); I cannot use LibPQ.load! because I don’t want to execute…

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## [Fail to execute jl. file](https://discourse.julialang.org/t/fail-to-execute-jl-file/59590)

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**Author:** [@Rafael\_Brus](https://discourse.julialang.org/u/Rafael_Brus)\
**Replies:** 4\
**Last updated:** [April 20, 2021, 12:11pm UTC](https://discourse.julialang.org/t/fail-to-execute-jl-file/59590 "2021-04-20T12:11:02Z")

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How can I execute this code by clicking on the jl file on windows? using Gtk ls = GtkListStore(String, Int, Bool) push!(ls,("Peter",20,false)) push!(ls,("Paul",30,false)) push!(ls,("Mary",25,true)) insert!(ls, 2, ("Sus…

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## [Column selection in DataFrames comb](https://discourse.julialang.org/t/column-selection-in-dataframes-comb/59648)

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**Author:** [@danielw2904](https://discourse.julialang.org/u/danielw2904)\
**Replies:** 3\
**Last updated:** [April 20, 2021, 12:08pm UTC](https://discourse.julialang.org/t/column-selection-in-dataframes-comb/59648 "2021-04-20T12:08:53Z")

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I think I am misunderstanding the column selection in grouped DataFrames. I would like to select a range of variables in a combine operation but I cannot make it work with any of the DataAPI selectors: using DataFrames,…

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## [How to arrange data for time series forecasting (mini-batching) without violoating the GPU memory for a LSTM?](https://discourse.julialang.org/t/how-to-arrange-data-for-time-series-forecasting-mini-batching-without-violoating-the-gpu-memory-for-a-lstm/54171)

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**Author:** [@Volker](https://discourse.julialang.org/u/Volker)\
**Replies:** 7\
**Last updated:** [April 20, 2021, 11:10am UTC](https://discourse.julialang.org/t/how-to-arrange-data-for-time-series-forecasting-mini-batching-without-violoating-the-gpu-memory-for-a-lstm/54171 "2021-04-20T11:10:01Z")

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Hi, I would like to know how I have to arrange data for time series forecasting (mini-batching) without violoating the GPU memory for a LSTM. I tried to follow the instructions of @jeremiedb of the following link: http…

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## [Efficient structure of Unitful arrays](https://discourse.julialang.org/t/efficient-structure-of-unitful-arrays/59612)

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**Author:** [@snowgum](https://discourse.julialang.org/u/snowgum)\
**Replies:** 8\
**Last updated:** [April 20, 2021, 10:54am UTC](https://discourse.julialang.org/t/efficient-structure-of-unitful-arrays/59612 "2021-04-20T10:54:40Z")

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I’m experiencing performance issues when using Unitful arrays inside a structure. I don’t know how to specify the type so well, so the problem may be from the type definition. Here is a simple example using a struct and…

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## [Accessing values in a matrix for a column before the first?](https://discourse.julialang.org/t/accessing-values-in-a-matrix-for-a-column-before-the-first/59634)

<div class="topic-metadata">

**Author:** [@mdsa3d](https://discourse.julialang.org/u/mdsa3d)\
**Replies:** 4\
**Last updated:** [April 20, 2021, 10:46am UTC](https://discourse.julialang.org/t/accessing-values-in-a-matrix-for-a-column-before-the-first/59634 "2021-04-20T10:46:10Z")

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I am trying to access elements of the previous columns than first column. For example in python if i try to access elements before the first column 0 it will return an empty array. import numpy as np x = np.matrix(\[\[ 1…

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## [Simulated annealing Algorithm](https://discourse.julialang.org/t/simulated-annealing-algorithm/41503)

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**Author:** [@A.U.M](https://discourse.julialang.org/u/A.U.M)\
**Replies:** 13\
**Last updated:** [April 20, 2021, 10:01am UTC](https://discourse.julialang.org/t/simulated-annealing-algorithm/41503 "2021-04-20T10:01:28Z")

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Hello, I am trying to implement a basic simulated annealing Algorithm and test it on some benchmarks but when I test it on Rosenbrock Function I got some errors ( MethodError: objects of type Int64 are not callable ) an…

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## [String encoding with DelimitedFiles](https://discourse.julialang.org/t/string-encoding-with-delimitedfiles/59646)

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**Author:** [@amrods](https://discourse.julialang.org/u/amrods)\
**Replies:** 8\
**Last updated:** [April 20, 2021, 9:45am UTC](https://discourse.julialang.org/t/string-encoding-with-delimitedfiles/59646 "2021-04-20T09:45:50Z")

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I’m importing some files with DelimitedFiles and I keep getting some weird characters in the header. For example: julia\> using DelimitedFiles julia\> csv, names = readdlm("data1.csv", ',', header=true) julia\> names 1×5…

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