# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1677

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

**Page:** 1678

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## [Read multiple csv files](https://discourse.julialang.org/t/read-multiple-csv-files/43806)

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**Author:** [@Ruan\_Stander](https://discourse.julialang.org/u/Ruan_Stander)\
**Replies:** 1\
**Last updated:** [July 28, 2020, 9:33am UTC](https://discourse.julialang.org/t/read-multiple-csv-files/43806 "2020-07-28T09:33:35Z")

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How should I approach reading multiple files in one CSV.File call ? fileDirectory="d:/Data/Test/" using Glob files=glob("\*.txt", fileDirectory) df3=DataFrame(CSV.File(files)) MethodError: no method matching joinpath(:…

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## [Let expression problem](https://discourse.julialang.org/t/let-expression-problem/43734)

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**Author:** [@Qiyamah](https://discourse.julialang.org/u/Qiyamah)\
**Replies:** 6\
**Last updated:** [July 28, 2020, 9:08am UTC](https://discourse.julialang.org/t/let-expression-problem/43734 "2020-07-28T09:08:02Z")

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x=1 y=2 z=3 u=4 a=5 v=6 let x=11, y=11, z::Int=11, u::Int=11, v=(a=11; 22) x=22 println("x = ", x) println("y = ", y) …

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## [Help finding what's causing a semi-hang](https://discourse.julialang.org/t/help-finding-whats-causing-a-semi-hang/43805)

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**Author:** [@akdor1154](https://discourse.julialang.org/u/akdor1154)\
**Replies:** 0\
**Last updated:** [July 28, 2020, 9:03am UTC](https://discourse.julialang.org/t/help-finding-whats-causing-a-semi-hang/43805 "2020-07-28T09:03:24Z")

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Hey guys, I’ve just found some really strange (and irritating) behaviour: when both IndexedTables and DataFrames are using-ed, IndexedTables.table() takes like 5 minutes to run if a certain argument is passed. To reprod…

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## [Parser support for open/closed interval notation?](https://discourse.julialang.org/t/parser-support-for-open-closed-interval-notation/43781)

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**Author:** [@cce](https://discourse.julialang.org/u/cce)\
**Replies:** 1\
**Last updated:** [July 28, 2020, 8:37am UTC](https://discourse.julialang.org/t/parser-support-for-open-closed-interval-notation/43781 "2020-07-28T08:37:21Z")

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I’m working with Interval{DateTime} these days, in particular, within a medical data processing application that requires modeling of with closed/open endpoints. It’s inconvenient to write/update intervals due to the pe…

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## [Send lines to REPL in Tmux](https://discourse.julialang.org/t/send-lines-to-repl-in-tmux/43772)

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**Author:** [@natema](https://discourse.julialang.org/u/natema)\
**Replies:** 2\
**Last updated:** [July 28, 2020, 8:33am UTC](https://discourse.julialang.org/t/send-lines-to-repl-in-tmux/43772 "2020-07-28T08:33:44Z")

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I’d like to share one way to get the evaluate line behavior of Juno/VSCode in Tmux. Just a bit of context on why I’m trying to do that: today I found myself with three weeks to go without my laptop and very limited inte…

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## [Create eventplot using PyPlot.jl through Plots.jl](https://discourse.julialang.org/t/create-eventplot-using-pyplot-jl-through-plots-jl/43802)

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**Author:** [@smonsays](https://discourse.julialang.org/u/smonsays)\
**Replies:** 0\
**Last updated:** [July 28, 2020, 7:36am UTC](https://discourse.julialang.org/t/create-eventplot-using-pyplot-jl-through-plots-jl/43802 "2020-07-28T07:36:18Z")

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I would like to create what matplotlib calls an eventplot. As far as I understand, this is only viable through the PyPlot backend for Plots. I tried the following: using Random using Plots pyplot() events = rand((0,1),…

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## [Can Julia really be used as a scripting language? (Performance)](https://discourse.julialang.org/t/can-julia-really-be-used-as-a-scripting-language-performance/40384)

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**Author:** [@singpolyma](https://discourse.julialang.org/u/singpolyma)\
**Replies:** 69\
**Last updated:** [July 28, 2020, 6:50am UTC](https://discourse.julialang.org/t/can-julia-really-be-used-as-a-scripting-language-performance/40384 "2020-07-28T06:50:48Z")

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I’ve been reading the docs, and getting pretty excited about Julia’s potential as a replacement for Ruby in my workflows, however I very quickly seem to have run into a brick wall once trying to actually use it: it’s inc…

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## [Why do we need to define separate methods for commutative binary operators?](https://discourse.julialang.org/t/why-do-we-need-to-define-separate-methods-for-commutative-binary-operators/42044)

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**Author:** [@jishnub](https://discourse.julialang.org/u/jishnub)\
**Replies:** 12\
**Last updated:** [July 28, 2020, 6:37am UTC](https://discourse.julialang.org/t/why-do-we-need-to-define-separate-methods-for-commutative-binary-operators/42044 "2020-07-28T06:37:07Z")

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Eg: julia\> struct abc x :: Int end julia\> Base.:(+)(a::abc, b::Int) = abc(a.x + b) julia\> abc(1) + 1 abc(2) julia\> 1 + abc(1) ERROR: MethodError: no method matching +(::Int64, ::abc) julia\> Base.:(==)(…

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## [Transforming \`GeometryBasics.Ngon\` using \`CoordinateTransformations\`](https://discourse.julialang.org/t/transforming-geometrybasics-ngon-using-coordinatetransformations/42680)

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**Author:** [@lassepe](https://discourse.julialang.org/u/lassepe)\
**Replies:** 2\
**Last updated:** [July 28, 2020, 6:22am UTC](https://discourse.julialang.org/t/transforming-geometrybasics-ngon-using-coordinatetransformations/42680 "2020-07-28T06:22:04Z")

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I am trying to transform some GeometryBasics.Line objects using CoordinateTransformations but I can’t find a convenient way to transform anything other than GeometryBasics.Point out of the box. For example, if I have u…

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## [Implementing dosing regimens in diffeq](https://discourse.julialang.org/t/implementing-dosing-regimens-in-diffeq/43173)

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**Author:** [@Janssena](https://discourse.julialang.org/u/Janssena)\
**Replies:** 2\
**Last updated:** [July 28, 2020, 6:15am UTC](https://discourse.julialang.org/t/implementing-dosing-regimens-in-diffeq/43173 "2020-07-28T06:15:18Z")

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Hey all, I’ve been working to implement a complex dosing regimen consisting of both IV bolus doses and continuous IV infusions. An example would be: t = -80, dose = 1000, rate = 0 t = -2, dose = 2500, rate = 100 t =…

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## [JuliaCon 2020 is Live!](https://discourse.julialang.org/t/juliacon-2020-is-live/43623)

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**Author:** [@mbauman](https://discourse.julialang.org/u/mbauman)\
**Replies:** 3\
**Last updated:** [July 28, 2020, 4:07am UTC](https://discourse.julialang.org/t/juliacon-2020-is-live/43623 "2020-07-28T04:07:58Z")

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JuliaCon 2020 is Live! The workshops were a great success, with the second day of talks today. If you haven’t done so yet, register for free today so you can more fully participate in the sessions. Find the complete sche…

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## [Clearing a scene in Makie](https://discourse.julialang.org/t/clearing-a-scene-in-makie/43790)

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**Author:** [@pauljurczak](https://discourse.julialang.org/u/pauljurczak)\
**Replies:** 1\
**Last updated:** [July 28, 2020, 3:54am UTC](https://discourse.julialang.org/t/clearing-a-scene-in-makie/43790 "2020-07-28T03:54:28Z")

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I have a visualization with sub-scenes. scene2 displays a polyline with text labels. Polylines change depending on mouse selections in scene1. I would like to be able to clear scene2 in example below at commented line: u…

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## [Question about writting custom training function using Flux.jl](https://discourse.julialang.org/t/question-about-writting-custom-training-function-using-flux-jl/43743)

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**Author:** [@XiaodongMa-MRI](https://discourse.julialang.org/u/XiaodongMa-MRI)\
**Replies:** 2\
**Last updated:** [July 28, 2020, 1:27am UTC](https://discourse.julialang.org/t/question-about-writting-custom-training-function-using-flux-jl/43743 "2020-07-28T01:27:02Z")

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Hello, I am trying to write a custom training function instead of using Flux!train, following the documentation https://fluxml.ai/Flux.jl/stable/training/training/#Model-parameters-1, but it will pop up error message “O…

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## [Why the separation of \`ODEProblem\` and \`solve\` in DifferentialEquations.jl?](https://discourse.julialang.org/t/why-the-separation-of-odeproblem-and-solve-in-differentialequations-jl/43737)

<div class="topic-metadata">

**Author:** [@Samuel\_Ainsworth](https://discourse.julialang.org/u/Samuel_Ainsworth)\
**Replies:** 13\
**Last updated:** [July 28, 2020, 1:10am UTC](https://discourse.julialang.org/t/why-the-separation-of-odeproblem-and-solve-in-differentialequations-jl/43737 "2020-07-28T01:10:54Z")

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Is there a performance benefit to reusing ODEProblems? I’m curious why the ODEProblem struct/function if the equivalent info could also just be handed off to solve? I have a problem where I repeatedly need to solve the …

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## [How to pass a function in a variable inside a linear regression?](https://discourse.julialang.org/t/how-to-pass-a-function-in-a-variable-inside-a-linear-regression/43793)

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**Author:** [@pauloat](https://discourse.julialang.org/u/pauloat)\
**Replies:** 2\
**Last updated:** [July 28, 2020, 12:12am UTC](https://discourse.julialang.org/t/how-to-pass-a-function-in-a-variable-inside-a-linear-regression/43793 "2020-07-28T00:12:31Z")

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Hi, im trying to replicate this excercises in R, but in Julia and wanted to know if there’s a way to do what they did in 2.2, that is, passing a linear model the next way linearRegressor = lm(log(dependente variable ) …

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## [ANN: Convex 0.13 released](https://discourse.julialang.org/t/ann-convex-0-13-released/35304)

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**Author:** [@ericphanson](https://discourse.julialang.org/u/ericphanson)\
**Replies:** 2\
**Last updated:** [July 27, 2020, 10:38pm UTC](https://discourse.julialang.org/t/ann-convex-0-13-released/35304 "2020-07-27T22:38:03Z")

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This is a breaking release to Convex.jl which switches the backend from the deprecated MathProgBase to MathOptInterface (usually shortened to MOI). This means that one should use MOI-compatible solvers. For example, if y…

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## [Is it correct that it recompiles packages every time a new REPL is opened?](https://discourse.julialang.org/t/is-it-correct-that-it-recompiles-packages-every-time-a-new-repl-is-opened/30266)

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**Author:** [@Nycto](https://discourse.julialang.org/u/Nycto)\
**Replies:** 10\
**Last updated:** [July 27, 2020, 10:23pm UTC](https://discourse.julialang.org/t/is-it-correct-that-it-recompiles-packages-every-time-a-new-repl-is-opened/30266 "2020-07-27T22:23:31Z")

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E.g. the first time you use plots.jl after opening a new REPL it has to recompile. I was thinking that since the code is unchanged, shouldn’t it just use the old compiled version? Is it going to always recompile, or is t…

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## [Having to press Enter twice with autocompletion](https://discourse.julialang.org/t/having-to-press-enter-twice-with-autocompletion/43787)

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**Author:** [@pauljurczak](https://discourse.julialang.org/u/pauljurczak)\
**Replies:** 3\
**Last updated:** [July 27, 2020, 8:22pm UTC](https://discourse.julialang.org/t/having-to-press-enter-twice-with-autocompletion/43787 "2020-07-27T20:22:55Z")

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Is there a way not to have to press enter twice with autocompletion when you just type the whole keyword? For example, here I have to press Enter twice after typing end: In practical terms: deactivate autocomplete whe…

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## [Postdoc and Ph.D. openings associated with a Skoltech/MIT project](https://discourse.julialang.org/t/postdoc-and-ph-d-openings-associated-with-a-skoltech-mit-project/43785)

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**Author:** [@David\_Pozo](https://discourse.julialang.org/u/David_Pozo)\
**Replies:** 0\
**Last updated:** [July 27, 2020, 7:40pm UTC](https://discourse.julialang.org/t/postdoc-and-ph-d-openings-associated-with-a-skoltech-mit-project/43785 "2020-07-27T19:40:12Z")

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Dear colleagues, We are looking for two excellent and motivated Post-doctoral researchers and 2 Ph.D. candidates in the frame of a 3-year joint project between the Skolkovo Institute of Science and Technology (Skoltec…

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## [How to make faster in a matrix multiplication inside a loop?](https://discourse.julialang.org/t/how-to-make-faster-in-a-matrix-multiplication-inside-a-loop/43783)

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**Author:** [@jmcastro2109](https://discourse.julialang.org/u/jmcastro2109)\
**Replies:** 2\
**Last updated:** [July 27, 2020, 6:48pm UTC](https://discourse.julialang.org/t/how-to-make-faster-in-a-matrix-multiplication-inside-a-loop/43783 "2020-07-27T18:48:19Z")

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Hi! Is there a way to implement the following function faster? Seeds = rand(200,90,15000,10) Mat = rand(200,200) @views function testfunction(Seeds,Mat) (J,T,N,S) = size(Seeds) ν = zeros(Float32,J,T,N,S)…

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## [Classification of numbers using metaprogramming](https://discourse.julialang.org/t/classification-of-numbers-using-metaprogramming/43775)

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**Author:** [@j\_tanu](https://discourse.julialang.org/u/j_tanu)\
**Replies:** 4\
**Last updated:** [July 27, 2020, 5:36pm UTC](https://discourse.julialang.org/t/classification-of-numbers-using-metaprogramming/43775 "2020-07-27T17:36:55Z")

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Hi, I am trying to classify a large set of floating-point numbers in various range and count them. I want to divide them into a large no of classes. Practically it is impossible to write every clause using an if-else ki…

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## [Multithreading on a Linux HPC cluster](https://discourse.julialang.org/t/multithreading-on-a-linux-hpc-cluster/43780)

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**Author:** [@CameronBieganek](https://discourse.julialang.org/u/CameronBieganek)\
**Replies:** 0\
**Last updated:** [July 27, 2020, 5:32pm UTC](https://discourse.julialang.org/t/multithreading-on-a-linux-hpc-cluster/43780 "2020-07-27T17:32:30Z")

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I’m running some machine learning code on a linux HPC cluster that is managed by a PBS scheduler. The code consists mostly of training a bunch of random forests using MLJ.jl and DecisionTree.jl. DecisionTree.jl uses mult…

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## [Matrix input](https://discourse.julialang.org/t/matrix-input/43776)

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**Author:** [@mamo](https://discourse.julialang.org/u/mamo)\
**Replies:** 2\
**Last updated:** [July 27, 2020, 5:16pm UTC](https://discourse.julialang.org/t/matrix-input/43776 "2020-07-27T17:16:46Z")

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If I have a matrix input: A=\[. . . 25; 12 . . .\] dots mean that there are no value for that i-j combination. Zeros are not appropriate since the inputs will be used for division. Are the dots interpreted as non-exist…

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## [How to generate Coverage for CUDA functions](https://discourse.julialang.org/t/how-to-generate-coverage-for-cuda-functions/43752)

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**Author:** [@Zitzeronion](https://discourse.julialang.org/u/Zitzeronion)\
**Replies:** 2\
**Last updated:** [July 27, 2020, 4:56pm UTC](https://discourse.julialang.org/t/how-to-generate-coverage-for-cuda-functions/43752 "2020-07-27T16:56:40Z")

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Hey there I have a hard time getting the correct coverage for my small project. So I am trying to do simple CFD and run most of the computation on the GPU with CUDA.jl. Everything works as I would expect it and the tes…

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## [Matrix computation](https://discourse.julialang.org/t/matrix-computation/42835)

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**Author:** [@nhavt](https://discourse.julialang.org/u/nhavt)\
**Replies:** 6\
**Last updated:** [July 27, 2020, 4:36pm UTC](https://discourse.julialang.org/t/matrix-computation/42835 "2020-07-27T16:36:27Z")

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Hello all, I have the following function that I would need to optimize. This is because this function is called multiple times (at least 500). So, it is crucial to optimize this function. The computing time with my comp…

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## [Julia+JuMP performances](https://discourse.julialang.org/t/julia-jump-performances/43766)

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**Author:** [@mamo](https://discourse.julialang.org/u/mamo)\
**Replies:** 2\
**Last updated:** [July 27, 2020, 4:24pm UTC](https://discourse.julialang.org/t/julia-jump-performances/43766 "2020-07-27T16:24:29Z")

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A question for Julia community. The problem I have has: \_nvars = 2483610 \_ncons = 1269620 \_total\_solve\_time = 91.625 sec Solver is AMPL+CPLEX. Is this a feasible problem for JuMP + GLPK? Anybody compared performanc…

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## [Lost: Hoverall "structure" of the conference ? Missing an "about" session](https://discourse.julialang.org/t/lost-hoverall-structure-of-the-conference-missing-an-about-session/43745)

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**Author:** [@sylvaticus](https://discourse.julialang.org/u/sylvaticus)\
**Replies:** 4\
**Last updated:** [July 27, 2020, 4:18pm UTC](https://discourse.julialang.org/t/lost-hoverall-structure-of-the-conference-missing-an-about-session/43745 "2020-07-27T16:18:40Z")

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I have often a problem with large conferences. I feel lost. I need to have a nice schedule, maybe with a discussion on which is the rational of the organisation. So, you have red track, green track, BOF… do they mean s…

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## [Weird behavior calling FORTRAN function](https://discourse.julialang.org/t/weird-behavior-calling-fortran-function/43764)

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**Author:** [@AstroBarker](https://discourse.julialang.org/u/AstroBarker)\
**Replies:** 6\
**Last updated:** [July 27, 2020, 4:18pm UTC](https://discourse.julialang.org/t/weird-behavior-calling-fortran-function/43764 "2020-07-27T16:18:40Z")

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I have a Julia function that calls a FORTRAN subroutine that I have written. Everything was working fine until recently I tried to change the return type of the Julia function - an array of the FORTRAN returns instead of…

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## [Calling fortran function](https://discourse.julialang.org/t/calling-fortran-function/2288)

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**Author:** [@bdeonovic](https://discourse.julialang.org/u/bdeonovic)\
**Replies:** 10\
**Last updated:** [February 25, 2017, 7:23pm UTC](https://discourse.julialang.org/t/calling-fortran-function/2288 "2017-02-25T19:23:59Z")

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Trying to call a fortran function. The fortran library is qrupdate. The fortran files were compiled with flags -fimplicit-none -O3 -funroll-loops -fPIC using gfortran. My julia command looks like ccall(("sqrinr\_","…

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## [Ccall julia ReadOnlyMemoryError()](https://discourse.julialang.org/t/ccall-julia-readonlymemoryerror/43765)

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**Author:** [@Ashwin\_Sundarka](https://discourse.julialang.org/u/Ashwin_Sundarka)\
**Replies:** 0\
**Last updated:** [July 27, 2020, 3:23pm UTC](https://discourse.julialang.org/t/ccall-julia-readonlymemoryerror/43765 "2020-07-27T15:23:49Z")

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Hii! I am calling a C function from Julia using ccall. When I am running using a small data size it works perfectly but when I am using a huge data size it gives error ReadOnlyMemoryError() I tried to show a demo of my…

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