# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1591

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

**Page:** 1592

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## [Difference-Differential system in ModelingToolkit.jl](https://discourse.julialang.org/t/difference-differential-system-in-modelingtoolkit-jl/48605)

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**Author:** [@Honza9723](https://discourse.julialang.org/u/Honza9723)\
**Replies:** 5\
**Last updated:** [October 26, 2020, 7:34pm UTC](https://discourse.julialang.org/t/difference-differential-system-in-modelingtoolkit-jl/48605 "2020-10-26T19:34:10Z")

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Dear All, I would like to ask for advice regarding ModellingToolkit.jl. I am working on a problem (macroeconomic model) that reduces to the solution of a highly nonlinear dynamic system. Because of high-nonlinearity and…

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## [Large sum returns negative numbers in julia](https://discourse.julialang.org/t/large-sum-returns-negative-numbers-in-julia/49032)

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**Author:** [@dashanan](https://discourse.julialang.org/u/dashanan)\
**Replies:** 5\
**Last updated:** [October 26, 2020, 6:55pm UTC](https://discourse.julialang.org/t/large-sum-returns-negative-numbers-in-julia/49032 "2020-10-26T18:55:22Z")

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hello , i am trying to do a counter for some problem I am having, but while I was testing I see that Julia was returning negative numbers after some time, I have no idea why this is happening, now to check that, i ha…

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## [Formalizing a governance structure for JuMP](https://discourse.julialang.org/t/formalizing-a-governance-structure-for-jump/49017)

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**Author:** [@odow](https://discourse.julialang.org/u/odow)\
**Replies:** 2\
**Last updated:** [October 26, 2020, 6:53pm UTC](https://discourse.julialang.org/t/formalizing-a-governance-structure-for-jump/49017 "2020-10-26T18:53:23Z")

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Dear all, Recently, JuMP turned eight years old. (The first commit for “Julp” was made on 10 October 2012!) It has come a long way since it’s creation as a side-project of two graduate students at MIT, and as we approac…

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## [Method that acts on union types, what is wrong?](https://discourse.julialang.org/t/method-that-acts-on-union-types-what-is-wrong/49057)

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**Author:** [@lmiq](https://discourse.julialang.org/u/lmiq)\
**Replies:** 8\
**Last updated:** [October 26, 2020, 5:55pm UTC](https://discourse.julialang.org/t/method-that-acts-on-union-types-what-is-wrong/49057 "2020-10-26T17:55:08Z")

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What is wrong with this definition of a method that is thought to work on both types defined? julia\> struct A end julia\> struct B end julia\> function test( x :: T, y :: T ) where T \<: Union{A,B} true e…

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## [MethodError when solving SDE in DifferentialEquations.jl](https://discourse.julialang.org/t/methoderror-when-solving-sde-in-differentialequations-jl/49053)

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**Author:** [@Sam\_Power](https://discourse.julialang.org/u/Sam_Power)\
**Replies:** 4\
**Last updated:** [October 26, 2020, 5:35pm UTC](https://discourse.julialang.org/t/methoderror-when-solving-sde-in-differentialequations-jl/49053 "2020-10-26T17:35:14Z")

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Hi, Apologies for not having a more informative title. I’m having a little trouble solving a 2-dimensional SDE in DifferentialEquations.jl. My current code is using DifferentialEquations, ForwardDiff # Solve Chemical …

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## [Representation of ODEs with mix of Matrix and Vector Components](https://discourse.julialang.org/t/representation-of-odes-with-mix-of-matrix-and-vector-components/48687)

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**Author:** [@Sam\_Power](https://discourse.julialang.org/u/Sam_Power)\
**Replies:** 8\
**Last updated:** [October 26, 2020, 4:52pm UTC](https://discourse.julialang.org/t/representation-of-odes-with-mix-of-matrix-and-vector-components/48687 "2020-10-26T16:52:51Z")

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Hi, I’m currently using DifferentialEquations.jl to solve some ODEs arising in Chemical Reaction Networks, in particular the Linear Noise Approximation to the Chemical Langevin Equation. In my example, the ODE involves…

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## [Graph processing framework](https://discourse.julialang.org/t/graph-processing-framework/48987)

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**Author:** [@Aje12](https://discourse.julialang.org/u/Aje12)\
**Replies:** 2\
**Last updated:** [October 26, 2020, 4:20pm UTC](https://discourse.julialang.org/t/graph-processing-framework/48987 "2020-10-26T16:20:32Z")

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Hi everyone, I am new to Julia as of my final university project. I have been tasked with creating a graph processing framework similar to the Ligra API in C++. Does anybody have any tips or ideas? I have been looking o…

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## [Visualizing the grid JuAFEM](https://discourse.julialang.org/t/visualizing-the-grid-juafem/49052)

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**Author:** [@Hrishikesh\_Das](https://discourse.julialang.org/u/Hrishikesh_Das)\
**Replies:** 1\
**Last updated:** [October 26, 2020, 3:50pm UTC](https://discourse.julialang.org/t/visualizing-the-grid-juafem/49052 "2020-10-26T15:50:44Z")

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I am new to Julia. Cn someone tell me how to visualize the grid I have generated?

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## [Set Id of struct on construction](https://discourse.julialang.org/t/set-id-of-struct-on-construction/48977)

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**Author:** [@cojua8](https://discourse.julialang.org/u/cojua8)\
**Replies:** 9\
**Last updated:** [October 26, 2020, 3:44pm UTC](https://discourse.julialang.org/t/set-id-of-struct-on-construction/48977 "2020-10-26T15:44:19Z")

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Hi, I’m trying to implement a struct that must have an Id, which is set on construction, similar to C# static member So far, I have been able to do it like this: x = 0 struct A prop1 id A(prop1) = begin …

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## [Base.precompile appears not to work](https://discourse.julialang.org/t/base-precompile-appears-not-to-work/49027)

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**Author:** [@Benny](https://discourse.julialang.org/u/Benny)\
**Replies:** 2\
**Last updated:** [October 26, 2020, 2:33pm UTC](https://discourse.julialang.org/t/base-precompile-appears-not-to-work/49027 "2020-10-26T14:33:01Z")

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I found out about Base.precompile for compiling functions without running, so I tried it out. It doesn’t seem to work though when I put this in the REPL: \> using Plots \> precompile(plot, (typeof(rand(10)),) ) # returns…

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## [JunoLab: Cannot Interrupt/Kill Julia Process Midway](https://discourse.julialang.org/t/junolab-cannot-interrupt-kill-julia-process-midway/19336)

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**Author:** [@Piper](https://discourse.julialang.org/u/Piper)\
**Replies:** 10\
**Last updated:** [October 26, 2020, 2:04pm UTC](https://discourse.julialang.org/t/junolab-cannot-interrupt-kill-julia-process-midway/19336 "2020-10-26T14:04:03Z")

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Hello! I posted about this on the Atom discussion page, but I was recommended to post it here as well. I am currently using Atom version 1.33.1 on Windows 10 to execute Julia code through the JunoLab package, and I’m u…

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## [Scope of parametric types and associated error messages](https://discourse.julialang.org/t/scope-of-parametric-types-and-associated-error-messages/48928)

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**Author:** [@plafl](https://discourse.julialang.org/u/plafl)\
**Replies:** 5\
**Last updated:** [October 26, 2020, 12:42pm UTC](https://discourse.julialang.org/t/scope-of-parametric-types-and-associated-error-messages/48928 "2020-10-26T12:42:38Z")

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Hello, first post here. Sorry it’s so long. I’m a little confused about the errors I’m getting with different levels of type annotations on a struct with an inner constructor. I have actually solved the problem but I ha…

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## [Improving performance of network sampling/inference algorithm](https://discourse.julialang.org/t/improving-performance-of-network-sampling-inference-algorithm/45536)

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**Author:** [@Adam\_Haber](https://discourse.julialang.org/u/Adam_Haber)\
**Replies:** 2\
**Last updated:** [October 26, 2020, 12:12pm UTC](https://discourse.julialang.org/t/improving-performance-of-network-sampling-inference-algorithm/45536 "2020-10-26T12:12:25Z")

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Hi, I’m trying to write a Julia package that does roughly what R’s ergm package does: fit, simulate and diagnose exponential-family models of networks. R’s ergm is an excellent and a very mature package, and I’m definit…

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## [Timed loop](https://discourse.julialang.org/t/timed-loop/48802)

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**Author:** [@yakir12](https://discourse.julialang.org/u/yakir12)\
**Replies:** 9\
**Last updated:** [October 26, 2020, 11:46am UTC](https://discourse.julialang.org/t/timed-loop/48802 "2020-10-26T11:46:09Z")

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I’m running a loop asynchronously. I’d like to have each iteration take at most max\_ns nanoseconds. Here’s what i have so far: function wait4it(t₀, max\_ns) t₁ = time\_ns() t = t₁ - t₀ if t \< max\_ns s …

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## [NamedArrays question / request](https://discourse.julialang.org/t/namedarrays-question-request/49021)

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**Author:** [@Lincoln\_Hannah](https://discourse.julialang.org/u/Lincoln_Hannah)\
**Replies:** 6\
**Last updated:** [October 26, 2020, 11:17am UTC](https://discourse.julialang.org/t/namedarrays-question-request/49021 "2020-10-26T11:17:40Z")

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Using NamedAarrays.jl I can define an array as: x = NamedArray( zeros(2,3,4), ( \[:A, :B\], \[:X, :Y, :Z\], 1:4 ), (:Dim1, :DimXYZ, :DimNum) ) I’d like to write it as: x = …

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## [Julia 1.5 + vscode runs very slow](https://discourse.julialang.org/t/julia-1-5-vscode-runs-very-slow/45483)

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**Author:** [@RaulDurand](https://discourse.julialang.org/u/RaulDurand)\
**Replies:** 3\
**Last updated:** [October 26, 2020, 10:21am UTC](https://discourse.julialang.org/t/julia-1-5-vscode-runs-very-slow/45483 "2020-10-26T10:21:32Z")

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Running code in vscode using Julia 1.5 is very slow. Even when using Ctrl+F5 it seems that it is running as if it were debugging since at the end it prints in the terminal: Julia debuggee finished. Press ENTER to close …

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## [Add row to 2D array in a loop](https://discourse.julialang.org/t/add-row-to-2d-array-in-a-loop/48993)

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**Author:** [@mhex](https://discourse.julialang.org/u/mhex)\
**Replies:** 2\
**Last updated:** [October 26, 2020, 9:50am UTC](https://discourse.julialang.org/t/add-row-to-2d-array-in-a-loop/48993 "2020-10-26T09:50:32Z")

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Hi, my aim is to add a new row to a 2D array in a for-loop. If I execute A = Array{Int64}(undef, 0, 2) A = \[A; \[1 2\]\] A = \[A; \[2 3\]\] println(A) I receive \[1 2; 2 3\] that is correct. But if I run it in a for loop: …

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## [Recommended serialization interface in Oct 2020: JLD, JLD2,](https://discourse.julialang.org/t/recommended-serialization-interface-in-oct-2020-jld-jld2/48994)

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**Author:** [@mkarikom](https://discourse.julialang.org/u/mkarikom)\
**Replies:** 6\
**Last updated:** [October 26, 2020, 9:49am UTC](https://discourse.julialang.org/t/recommended-serialization-interface-in-oct-2020-jld-jld2/48994 "2020-10-26T09:49:17Z")

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Obviously a corporation like Mathworks (for all its limitations) shines in its ability to define an official serialization interface: .mat (complexity of .mat versions aside) Is there any plan to do the same for JLDx? …

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## [In what way are Julia sets immutable?](https://discourse.julialang.org/t/in-what-way-are-julia-sets-immutable/49009)

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**Author:** [@Mark\_Graph](https://discourse.julialang.org/u/Mark_Graph)\
**Replies:** 5\
**Last updated:** [October 26, 2020, 9:46am UTC](https://discourse.julialang.org/t/in-what-way-are-julia-sets-immutable/49009 "2020-10-26T09:46:32Z")

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If I create a set in Julia, then Julia will tell me that the set is immutable. julia\> pets = Set(\["dog", "cat", "budgerigar"\]) Set{String} with 3 elements: "cat" "budgerigar" "dog" julia\> ismutable(pets) false N…

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## [Dropping missing values in dataframes](https://discourse.julialang.org/t/dropping-missing-values-in-dataframes/48967)

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**Author:** [@StatisticalMouse](https://discourse.julialang.org/u/StatisticalMouse)\
**Replies:** 14\
**Last updated:** [October 26, 2020, 9:13am UTC](https://discourse.julialang.org/t/dropping-missing-values-in-dataframes/48967 "2020-10-26T09:13:39Z")

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The dataframe column’s describe shows: 5 age 29.6991 0.42 28.0 80.0 177 Union{Missing, Float64} I can get rid of the missing values with this: replace!(train\_df.age, missing =\> median(skipmissing(train\_df\[:age\]))); H…

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## [Can unicode fraction symbols be used in equations](https://discourse.julialang.org/t/can-unicode-fraction-symbols-be-used-in-equations/49023)

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**Author:** [@Lincoln\_Hannah](https://discourse.julialang.org/u/Lincoln_Hannah)\
**Replies:** 2\
**Last updated:** [October 26, 2020, 5:13am UTC](https://discourse.julialang.org/t/can-unicode-fraction-symbols-be-used-in-equations/49023 "2020-10-26T05:13:29Z")

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I’d like to use ½ in equations e.g. X = 2 Y = ½X Is this possible? I just get error invalid character “½”

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## [Confusion about type stability of function within a struct](https://discourse.julialang.org/t/confusion-about-type-stability-of-function-within-a-struct/49003)

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**Author:** [@ash](https://discourse.julialang.org/u/ash)\
**Replies:** 1\
**Last updated:** [October 26, 2020, 1:03am UTC](https://discourse.julialang.org/t/confusion-about-type-stability-of-function-within-a-struct/49003 "2020-10-26T01:03:48Z")

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I have a struct called Operators that contains a bunch of functions. However, I can’t get it to be type stable. I have read Type Unstable: Function within a Struct and implemented the solution but it has not helped for t…

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## [Is garbage collection bad for gpu programming?](https://discourse.julialang.org/t/is-garbage-collection-bad-for-gpu-programming/48942)

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**Author:** [@lmiq](https://discourse.julialang.org/u/lmiq)\
**Replies:** 15\
**Last updated:** [October 25, 2020, 11:34pm UTC](https://discourse.julialang.org/t/is-garbage-collection-bad-for-gpu-programming/48942 "2020-10-25T23:34:48Z")

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I was hearing this podcast: and the Swift guy at a moment (about minute 56) said something like that no language would replace Python if one of the qualities of Python is not followed, concerning not having garbage co…

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## [Possible "multiple dispatch" due to API differences between package versions?](https://discourse.julialang.org/t/possible-multiple-dispatch-due-to-api-differences-between-package-versions/49005)

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**Author:** [@indycdrom](https://discourse.julialang.org/u/indycdrom)\
**Replies:** 1\
**Last updated:** [October 25, 2020, 10:15pm UTC](https://discourse.julialang.org/t/possible-multiple-dispatch-due-to-api-differences-between-package-versions/49005 "2020-10-25T22:15:44Z")

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hi there, I am wondering whether it is possible to have one function having multiple dispatches simply due to the API changes between package versions. For example, the newest version of ODBC.jl (v1.0.4), does no longe…

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## [Only one legend for scenarios](https://discourse.julialang.org/t/only-one-legend-for-scenarios/48991)

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**Author:** [@Arega\_Getaneh](https://discourse.julialang.org/u/Arega_Getaneh)\
**Replies:** 4\
**Last updated:** [October 25, 2020, 9:45pm UTC](https://discourse.julialang.org/t/only-one-legend-for-scenarios/48991 "2020-10-25T21:45:23Z")

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I wanted to have only one legened for this scenario generated plot instead of 11 similar names over my plot. How can I do that? t= \[1; 2; 3; 4; 5; 6; 7;8; 9; 10; 11; 12\] y= rand(12,24) plot(t,y, color="blue", linewidth…

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## [Legacy code on MacOS](https://discourse.julialang.org/t/legacy-code-on-macos/36580)

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**Author:** [@fipelle](https://discourse.julialang.org/u/fipelle)\
**Replies:** 3\
**Last updated:** [October 25, 2020, 8:21pm UTC](https://discourse.julialang.org/t/legacy-code-on-macos/36580 "2020-10-25T20:21:34Z")

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Hi all, I need to run an old code written for Julia 0.6.\*. I have installed Julia 0.6.4 on my macbook, but it does not work properly. As soon as I try to install common packages I get the following error message: ERROR…

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## [Julia newbie, interested in "learning by doing" in collaboration](https://discourse.julialang.org/t/julia-newbie-interested-in-learning-by-doing-in-collaboration/49001)

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**Author:** [@denka](https://discourse.julialang.org/u/denka)\
**Replies:** 0\
**Last updated:** [October 25, 2020, 8:12pm UTC](https://discourse.julialang.org/t/julia-newbie-interested-in-learning-by-doing-in-collaboration/49001 "2020-10-25T20:12:33Z")

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Hi! I am fascinated with a problem in Customer Data Platforms domain, striving to build a customer graph by feeding clickstream to a model. I would love to partner with likeminded folks to learn how to do it in Julia - …

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## [Multipath TCP awareness in Sockets.jl](https://discourse.julialang.org/t/multipath-tcp-awareness-in-sockets-jl/48952)

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**Author:** [@mks](https://discourse.julialang.org/u/mks)\
**Replies:** 3\
**Last updated:** [October 25, 2020, 7:50pm UTC](https://discourse.julialang.org/t/multipath-tcp-awareness-in-sockets-jl/48952 "2020-10-25T19:50:55Z")

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Hello, I’m new to the Julia community and currently try to understand the basic lower level networks terminology, even if it’s above my skill level. There is work going on by the IETF Multipath TCP Working Group that s…

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## [Zygote: CuArray only supports bits types](https://discourse.julialang.org/t/zygote-cuarray-only-supports-bits-types/48910)

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**Author:** [@Jack](https://discourse.julialang.org/u/Jack)\
**Replies:** 6\
**Last updated:** [October 25, 2020, 6:35pm UTC](https://discourse.julialang.org/t/zygote-cuarray-only-supports-bits-types/48910 "2020-10-25T18:35:48Z")

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Hi all, I encountered the ERROR: CuArray only supports bits types while doing gradient calculation. The calculation is a simple RNN that would pick the output sequence element based on sequence length in a batched tra…

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## [Where to put files used in src/test?](https://discourse.julialang.org/t/where-to-put-files-used-in-src-test/48984)

<div class="topic-metadata">

**Author:** [@mkarikom](https://discourse.julialang.org/u/mkarikom)\
**Replies:** 1\
**Last updated:** [October 25, 2020, 5:36pm UTC](https://discourse.julialang.org/t/where-to-put-files-used-in-src-test/48984 "2020-10-25T17:36:10Z")

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A couple of my unit tests read sample configs from external files (which also serve as examples for how to write user config files for various functions). Is there a convention on where to put these (eg /src/test/includ…

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