# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1863

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

**Page:** 1864

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## [When to ask on Discourse and when to ask on Stackoverflow?](https://discourse.julialang.org/t/when-to-ask-on-discourse-and-when-to-ask-on-stackoverflow/32172)

<div class="topic-metadata">

**Author:** [@xiaodai](https://discourse.julialang.org/u/xiaodai)\
**Replies:** 12\
**Last updated:** [December 12, 2019, 7:29pm UTC](https://discourse.julialang.org/t/when-to-ask-on-discourse-and-when-to-ask-on-stackoverflow/32172 "2019-12-12T19:29:02Z")

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I have been following a rule when I decide where to ask a question. I think the process is like this: If I think the problem has a definitive answer, and is based on something that has been definitely achieved then I …

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## [Parallel calculations with CUDA](https://discourse.julialang.org/t/parallel-calculations-with-cuda/32199)

<div class="topic-metadata">

**Author:** [@Diger](https://discourse.julialang.org/u/Diger)\
**Replies:** 0\
**Last updated:** [December 12, 2019, 5:30pm UTC](https://discourse.julialang.org/t/parallel-calculations-with-cuda/32199 "2019-12-12T17:30:31Z")

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I’m going through the tutorial https://juliagpu.gitlab.io/CuArrays.jl/tutorials/generated/intro/ and have some problems and errors. First the problems: I’m starting as in the tutorial using CuArrays, CUDAnative, Benchm…

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## [MIP starts in JuMP - an example](https://discourse.julialang.org/t/mip-starts-in-jump-an-example/32198)

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**Author:** [@angeloaliano1](https://discourse.julialang.org/u/angeloaliano1)\
**Replies:** 1\
**Last updated:** [December 12, 2019, 5:27pm UTC](https://discourse.julialang.org/t/mip-starts-in-jump-an-example/32198 "2019-12-12T17:27:19Z")

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Dear all, Could anyone provide a simple example of how can I use MIP starts in integer programming in Julia language? I have a problem and a feasible solution, but I cannot to use this solution inside of the CPLEX. Fo…

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## [Vspan vertical scale wrong when using dates as x axis](https://discourse.julialang.org/t/vspan-vertical-scale-wrong-when-using-dates-as-x-axis/31904)

<div class="topic-metadata">

**Author:** [@jdad](https://discourse.julialang.org/u/jdad)\
**Replies:** 3\
**Last updated:** [December 12, 2019, 3:39pm UTC](https://discourse.julialang.org/t/vspan-vertical-scale-wrong-when-using-dates-as-x-axis/31904 "2019-12-12T15:39:28Z")

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Hello, I am trying to use vspan to highlight specific periods in a plot with dates as x axis. It seems that vspan changes the y axis units to dates also (which is wrong). MWE : # Show vspan problem with date abscissae…

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## [Revise with Requires?](https://discourse.julialang.org/t/revise-with-requires/19347)

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**Author:** [@Raf](https://discourse.julialang.org/u/Raf)\
**Replies:** 14\
**Last updated:** [December 12, 2019, 1:11pm UTC](https://discourse.julialang.org/t/revise-with-requires/19347 "2019-12-12T13:11:26Z")

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Is there a way of getting Revise working on files included with Requires? My experience is files included in a @require block don’t get updated with Revise.

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## [Stacking layers example Flux - Flux.params empty](https://discourse.julialang.org/t/stacking-layers-example-flux-flux-params-empty/32186)

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**Author:** [@Volker](https://discourse.julialang.org/u/Volker)\
**Replies:** 2\
**Last updated:** [December 12, 2019, 12:26pm UTC](https://discourse.julialang.org/t/stacking-layers-example-flux-flux-params-empty/32186 "2019-12-12T12:26:45Z")

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Hi, I used the following example of the Flux documentation and when I execute the code the parameters are empty. using Flux struct Affine W b end Affine(in::Integer, out::Integer) = Affine(randn(out, in), rand…

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## [How to start numerous threads on windows](https://discourse.julialang.org/t/how-to-start-numerous-threads-on-windows/32144)

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**Author:** [@Diger](https://discourse.julialang.org/u/Diger)\
**Replies:** 6\
**Last updated:** [December 12, 2019, 11:58am UTC](https://discourse.julialang.org/t/how-to-start-numerous-threads-on-windows/32144 "2019-12-12T11:58:36Z")

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In the manual it says to use $ JULIA\_NUM\_THREADS=4 ./julia But how to invoke threads on windows with the julia icon?

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## [Stdlib tests that fail with v1.3.0 binary](https://discourse.julialang.org/t/stdlib-tests-that-fail-with-v1-3-0-binary/32159)

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**Author:** [@braydenware](https://discourse.julialang.org/u/braydenware)\
**Replies:** 4\
**Last updated:** [December 12, 2019, 9:42am UTC](https://discourse.julialang.org/t/stdlib-tests-that-fail-with-v1-3-0-binary/32159 "2019-12-12T09:42:11Z")

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I was building v1.3.0 from source, and out of habit ran make testall to make sure the tests pass with my build before I started using it. I had 52 tests fail from a variety of stdlib packages, so naturally I tried buildi…

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## [Issues with PGFPlotsX / PGFPlots](https://discourse.julialang.org/t/issues-with-pgfplotsx-pgfplots/32083)

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**Author:** [@ASF](https://discourse.julialang.org/u/ASF)\
**Replies:** 15\
**Last updated:** [December 12, 2019, 9:05am UTC](https://discourse.julialang.org/t/issues-with-pgfplotsx-pgfplots/32083 "2019-12-12T09:05:51Z")

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I’m trying to recreate this graph using PGFPlotsX but i cannot get it to render an image. I have pdf2svg, imagemagick and latex installed.

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## [Is there a bug in the flux convolution code?](https://discourse.julialang.org/t/is-there-a-bug-in-the-flux-convolution-code/32169)

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**Author:** [@jaynick](https://discourse.julialang.org/u/jaynick)\
**Replies:** 1\
**Last updated:** [December 12, 2019, 8:53am UTC](https://discourse.julialang.org/t/is-there-a-bug-in-the-flux-convolution-code/32169 "2019-12-12T08:53:50Z")

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Apology because this is a vague question, but: is there something wrong with the convolution code in Flux? Looking at the results of this example https://github.com/avik-pal/FastStyleTransfer.jl , they just do not “loo…

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## [Help with generating a function progamatically](https://discourse.julialang.org/t/help-with-generating-a-function-progamatically/32157)

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**Author:** [@DrChainsaw](https://discourse.julialang.org/u/DrChainsaw)\
**Replies:** 2\
**Last updated:** [December 12, 2019, 8:20am UTC](https://discourse.julialang.org/t/help-with-generating-a-function-progamatically/32157 "2019-12-12T08:20:07Z")

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Hi, I’m trying to generate a function (or an expression which evaluates to function to be precise) where arguments are given by a vector of symbols, perhaps easiest explained by this example: function fexpr() vars = \[:…

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## [Feedback on new package](https://discourse.julialang.org/t/feedback-on-new-package/31710)

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**Author:** [@venuur](https://discourse.julialang.org/u/venuur)\
**Replies:** 2\
**Last updated:** [December 12, 2019, 6:04am UTC](https://discourse.julialang.org/t/feedback-on-new-package/31710 "2019-12-12T06:04:20Z")

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I’m still pretty new to Julia so I’m looking for advice on how share a package. It ports over Unix style shell pattern matching from the Python module fnmatch: https://github.com/venuur/FnMatch.jl It should be usable f…

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## [Errors on new install of JuliaPro1.2.0 on Win10 x64 : LoadError and GitError](https://discourse.julialang.org/t/errors-on-new-install-of-juliapro1-2-0-on-win10-x64-loaderror-and-giterror/32179)

<div class="topic-metadata">

**Author:** [@kwic1975](https://discourse.julialang.org/u/kwic1975)\
**Replies:** 0\
**Last updated:** [December 12, 2019, 2:51am UTC](https://discourse.julialang.org/t/errors-on-new-install-of-juliapro1-2-0-on-win10-x64-loaderror-and-giterror/32179 "2019-12-12T02:51:02Z")

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Hello, I need some advice resolving installation of JuliaPro v1.2.0. I am very new to JuliaPro and I have tried the steps described below by running JuliaPro with administrator privileges and with current user privileges…

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## [Gadfly and flatten not defined](https://discourse.julialang.org/t/gadfly-and-flatten-not-defined/32161)

<div class="topic-metadata">

**Author:** [@alphasig329](https://discourse.julialang.org/u/alphasig329)\
**Replies:** 4\
**Last updated:** [December 12, 2019, 1:54am UTC](https://discourse.julialang.org/t/gadfly-and-flatten-not-defined/32161 "2019-12-12T01:54:35Z")

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using JuliaDB, JuliaDBMeta, DataFrames, Gadfly import Cairo import Fontconfig using Compose group\_data = JuliaDB.load("group\_data") test\_plot = Gadfly.plot( group\_data |\> DataFrame, x = "Group", …

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## [ZeroMQ vs. other transport protocols (such as nanomsg)?](https://discourse.julialang.org/t/zeromq-vs-other-transport-protocols-such-as-nanomsg/2136)

<div class="topic-metadata">

**Author:** [@ScottPJones](https://discourse.julialang.org/u/ScottPJones)\
**Replies:** 4\
**Last updated:** [December 12, 2019, 12:38am UTC](https://discourse.julialang.org/t/zeromq-vs-other-transport-protocols-such-as-nanomsg/2136 "2019-12-12T00:38:54Z")

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I’m interested in your opinion on ZMQ vs. other things such as nanomsg - we are currently also using ZeroMQ for communications in Julia (with our own wrapper), but one of the people at my company is concerned because th…

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## [Can't build Julia on Raspberry Pi zero locally on Raspbian buster](https://discourse.julialang.org/t/cant-build-julia-on-raspberry-pi-zero-locally-on-raspbian-buster/31378)

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**Author:** [@terasakisatoshi](https://discourse.julialang.org/u/terasakisatoshi)\
**Replies:** 4\
**Last updated:** [December 11, 2019, 11:47pm UTC](https://discourse.julialang.org/t/cant-build-julia-on-raspberry-pi-zero-locally-on-raspbian-buster/31378 "2019-12-11T23:47:10Z")

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I try to build Julia on Raspberry Pi(with Raspbian buster) zero without using Docker, but fails. For Julia v1.0.5, v1.1.1 and v1.2.0, I get error with the following message: In file included from /usr/include/c++/8/uti…

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## [Group DataFrames by a function of a column](https://discourse.julialang.org/t/group-dataframes-by-a-function-of-a-column/32173)

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**Author:** [@robsmith11](https://discourse.julialang.org/u/robsmith11)\
**Replies:** 4\
**Last updated:** [December 11, 2019, 11:29pm UTC](https://discourse.julialang.org/t/group-dataframes-by-a-function-of-a-column/32173 "2019-12-11T23:29:22Z")

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I’m starting to use DataFrames more frequently and find myself often having to create a temporary table and column just to get a transformed column by which to group. For example: julia\> d=DataFrame(x=rand(10^6)); jul…

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## [Ifelse statement leads to a length(hess\_I) \> 0 AssertionError](https://discourse.julialang.org/t/ifelse-statement-leads-to-a-length-hess-i-0-assertionerror/32139)

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**Author:** [@DanielPompermayer](https://discourse.julialang.org/u/DanielPompermayer)\
**Replies:** 3\
**Last updated:** [December 11, 2019, 9:02pm UTC](https://discourse.julialang.org/t/ifelse-statement-leads-to-a-length-hess-i-0-assertionerror/32139 "2019-12-11T21:02:32Z")

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Hey there, I’m new to JuMP but I need to solve an optimization problem which I am not being able to run. Let’s say I have a circumference with a given radius of 5 and such a circumference is built from the a and b comp…

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## [Can \`eltype()\` deduce the element type of a generator?](https://discourse.julialang.org/t/can-eltype-deduce-the-element-type-of-a-generator/6429)

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**Author:** [@Alexander\_Belopolsky](https://discourse.julialang.org/u/Alexander_Belopolsky)\
**Replies:** 30\
**Last updated:** [December 11, 2019, 8:40pm UTC](https://discourse.julialang.org/t/can-eltype-deduce-the-element-type-of-a-generator/6429 "2019-12-11T20:40:22Z")

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As of Julia Version 0.7.0-DEV.2036, calling eltype() on even the simplest generator returns Any: julia\> eltype(x for x in 1:2) Any Unless the generator function is very complicated, It does not look like a hard problem…

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## [Stop\_gradient/detach equivalent in flux](https://discourse.julialang.org/t/stop-gradient-detach-equivalent-in-flux/31926)

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**Author:** [@Rassibassi](https://discourse.julialang.org/u/Rassibassi)\
**Replies:** 2\
**Last updated:** [December 11, 2019, 8:34pm UTC](https://discourse.julialang.org/t/stop-gradient-detach-equivalent-in-flux/31926 "2019-12-11T20:34:14Z")

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Hi, is there an equivalent to Tensorflow’s stop\_gradient/PyTorch’s detach in FluxML? Thanks! Rasmus

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## [Autoencoder for telecommunication (Constellation shaping)](https://discourse.julialang.org/t/autoencoder-for-telecommunication-constellation-shaping/30613)

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**Author:** [@Rassibassi](https://discourse.julialang.org/u/Rassibassi)\
**Replies:** 4\
**Last updated:** [December 11, 2019, 8:32pm UTC](https://discourse.julialang.org/t/autoencoder-for-telecommunication-constellation-shaping/30613 "2019-12-11T20:32:25Z")

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Hi, in telecommunication one can use a autoencoder-ish structure to learn a channel code/constellation shape. I’ve got a working Tensorflow implementation for constellation shaping, but cannot make it work in Julia. I t…

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## [Solver-dependent callbacks in JuMP -- How to do it right?](https://discourse.julialang.org/t/solver-dependent-callbacks-in-jump-how-to-do-it-right/32130)

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**Author:** [@Henrique\_Becker](https://discourse.julialang.org/u/Henrique_Becker)\
**Replies:** 8\
**Last updated:** [December 11, 2019, 8:21pm UTC](https://discourse.julialang.org/t/solver-dependent-callbacks-in-jump-how-to-do-it-right/32130 "2019-12-11T20:21:11Z")

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Inspired by this answer, I tried to create a small example using the JuMP direct\_model together with solver-specific callbacks. I adapted the knapsack example provided with JuMP to reject solutions using the most efficie…

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## [Pkg.update() fails after upgrading to v1.3](https://discourse.julialang.org/t/pkg-update-fails-after-upgrading-to-v1-3/32165)

<div class="topic-metadata">

**Author:** [@bliang26](https://discourse.julialang.org/u/bliang26)\
**Replies:** 8\
**Last updated:** [December 11, 2019, 8:17pm UTC](https://discourse.julialang.org/t/pkg-update-fails-after-upgrading-to-v1-3/32165 "2019-12-11T20:17:12Z")

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I just upgraded Julia to v1.3 and Pkg.update() fails with the following message. It was working fine with v1.2. I tried deleting ~/.julia but it didn’t work. Please help. julia\> Pkg.update() Cloning default registries …

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## [Defining \`getindex\` for \`Tables.columntable\` objects](https://discourse.julialang.org/t/defining-getindex-for-tables-columntable-objects/31944)

<div class="topic-metadata">

**Author:** [@pdeffebach](https://discourse.julialang.org/u/pdeffebach)\
**Replies:** 2\
**Last updated:** [December 11, 2019, 6:15pm UTC](https://discourse.julialang.org/t/defining-getindex-for-tables-columntable-objects/31944 "2019-12-11T18:15:49Z")

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Let’s say you are working with tabular objects and for convenience and want to use t\[i, j\] getindexing (and not too many other functions) throughout your code. On the other hand you want to support the Tables.jl interfa…

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## [Copy with CuArrays and \`allowscalar(false)\`](https://discourse.julialang.org/t/copy-with-cuarrays-and-allowscalar-false/12341)

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**Author:** [@rveltz](https://discourse.julialang.org/u/rveltz)\
**Replies:** 6\
**Last updated:** [December 11, 2019, 6:08pm UTC](https://discourse.julialang.org/t/copy-with-cuarrays-and-allowscalar-false/12341 "2019-12-11T18:08:17Z")

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Hi, I am using CuArrays but the following operation seems unsupported: using CuArrays x=rand(10) |\> cu; CuArrays.allowscalar(false) V\[:,1\] .= x; It gives: ERROR: scalar getindex is disabled Using copy! from link is …

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## [WTF plots causing Signal desktop app to run?](https://discourse.julialang.org/t/wtf-plots-causing-signal-desktop-app-to-run/32126)

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**Author:** [@dlakelan](https://discourse.julialang.org/u/dlakelan)\
**Replies:** 6\
**Last updated:** [December 11, 2019, 5:55pm UTC](https://discourse.julialang.org/t/wtf-plots-causing-signal-desktop-app-to-run/32126 "2019-12-11T17:55:21Z")

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I am relatively new to Julia, I try to use it every so often. Right now I have a problem where I’m solving some diffusion problems and have some data that I want to plot. So, Queryverse looks nice, and I decide to try t…

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## [Custom layer with new parameters in Flux.jl](https://discourse.julialang.org/t/custom-layer-with-new-parameters-in-flux-jl/32143)

<div class="topic-metadata">

**Author:** [@Antomek](https://discourse.julialang.org/u/Antomek)\
**Replies:** 3\
**Last updated:** [December 11, 2019, 5:32pm UTC](https://discourse.julialang.org/t/custom-layer-with-new-parameters-in-flux-jl/32143 "2019-12-11T17:32:14Z")

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Hello everyone, I am new to Flux, but so far I really like it. I was trying to train a neural network where I wanted to include the gain of the sigmoidal activation functions in the cost function, to penalise small gai…

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## [Best practices for using random number generators with threads](https://discourse.julialang.org/t/best-practices-for-using-random-number-generators-with-threads/32158)

<div class="topic-metadata">

**Author:** [@dmbates](https://discourse.julialang.org/u/dmbates)\
**Replies:** 0\
**Last updated:** [December 11, 2019, 4:23pm UTC](https://discourse.julialang.org/t/best-practices-for-using-random-number-generators-with-threads/32158 "2019-12-11T16:23:02Z")

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In a single-threaded simulation it is common to pass the random number generator, of type AbstractRNG as the first argument in the method that actually performs the simulation and have another method without this argumen…

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## [Precompiling JuMP and GLPK cause segfaults](https://discourse.julialang.org/t/precompiling-jump-and-glpk-cause-segfaults/31905)

<div class="topic-metadata">

**Author:** [@amca01](https://discourse.julialang.org/u/amca01)\
**Replies:** 4\
**Last updated:** [December 11, 2019, 4:10pm UTC](https://discourse.julialang.org/t/precompiling-jump-and-glpk-cause-segfaults/31905 "2019-12-11T16:10:34Z")

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I’m using Julia 1.2.0. Just now, I tried to install JuMP and GLPK (using Pkg.add), and then tried to use them with using .... The attempt to precompile led to a slew of errors, and a segmentation fault (this is in Linu…

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## [Memory usage in nested loops](https://discourse.julialang.org/t/memory-usage-in-nested-loops/32098)

<div class="topic-metadata">

**Author:** [@M\_Kaj](https://discourse.julialang.org/u/M_Kaj)\
**Replies:** 2\
**Last updated:** [December 10, 2019, 3:44pm UTC](https://discourse.julialang.org/t/memory-usage-in-nested-loops/32098 "2019-12-10T15:44:17Z")

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Hey everyone, i would like to have some advise how to perform loops over vector multiplication. I need to do this for alot of vectors, so i try to use multi threading. The memory consumption of my function is really h…

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