# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1748

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

**Page:** 1749

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## [Packages: build, precompile and add](https://discourse.julialang.org/t/packages-build-precompile-and-add/39281)

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**Author:** [@v-i-s-h](https://discourse.julialang.org/u/v-i-s-h)\
**Replies:** 3\
**Last updated:** [May 13, 2020, 4:56am UTC](https://discourse.julialang.org/t/packages-build-precompile-and-add/39281 "2020-05-13T04:56:04Z")

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When I install some packages, upon first use it shows messages about building and/or precompile. Why these build/precompile tasks are not completed during the install phase itself? Now I do a manual build and precompile …

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## [Array/Vector multiplication for single element arrays](https://discourse.julialang.org/t/array-vector-multiplication-for-single-element-arrays/39377)

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**Author:** [@willcclarke](https://discourse.julialang.org/u/willcclarke)\
**Replies:** 8\
**Last updated:** [May 13, 2020, 3:15am UTC](https://discourse.julialang.org/t/array-vector-multiplication-for-single-element-arrays/39377 "2020-05-13T03:15:11Z")

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Hi, I’m a long term Matlab user just starting to wade into the world of Julia, so forgive me if my question is naive. I’m am currently writing some code to perform a number of matrix manipulation tasks. I came across wh…

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## [Passing a string into function as a expression](https://discourse.julialang.org/t/passing-a-string-into-function-as-a-expression/31625)

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**Author:** [@ke\_xu](https://discourse.julialang.org/u/ke_xu)\
**Replies:** 17\
**Last updated:** [May 12, 2020, 9:58pm UTC](https://discourse.julialang.org/t/passing-a-string-into-function-as-a-expression/31625 "2020-05-12T21:58:40Z")

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function Compare(a,b,c::String) d = Meta.parse(c) if eval(d) true else false end end Compare(1,1,"a\>b") I tried to compare two integers by a customized expression, like the function above…

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## [Proposal for deterministic memory management](https://discourse.julialang.org/t/proposal-for-deterministic-memory-management/39305)

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**Author:** [@Amin\_Yahyaabadi](https://discourse.julialang.org/u/Amin_Yahyaabadi)\
**Replies:** 53\
**Last updated:** [May 12, 2020, 9:29pm UTC](https://discourse.julialang.org/t/proposal-for-deterministic-memory-management/39305 "2020-05-12T21:29:01Z")

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I gave a proposal for deterministic memory management here: https://github.com/JuliaLang/julia/issues/7721#issuecomment-626123507

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## [@fastmath macro accuracy](https://discourse.julialang.org/t/fastmath-macro-accuracy/38847)

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**Author:** [@s-baumann](https://discourse.julialang.org/u/s-baumann)\
**Replies:** 26\
**Last updated:** [May 12, 2020, 9:06pm UTC](https://discourse.julialang.org/t/fastmath-macro-accuracy/38847 "2020-05-12T21:06:42Z")

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As I understand it @fastmath explores whatever functions you write and replaces them with fast and rough versions of these functions. For instance rather than the proper exp function you get a faster and less accurate ve…

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## [How to get Automa to work with stdin?](https://discourse.julialang.org/t/how-to-get-automa-to-work-with-stdin/39360)

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**Author:** [@lesshaste](https://discourse.julialang.org/u/lesshaste)\
**Replies:** 2\
**Last updated:** [May 12, 2020, 8:25pm UTC](https://discourse.julialang.org/t/how-to-get-automa-to-work-with-stdin/39360 "2020-05-12T20:25:00Z")

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I have some code which parses a string using Automa. I believe it simply travels through the string from left to right. I would like to make it work on a string coming from stdin but I am not sure how to do it. Here is …

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## [Sublime Text 3: Worth a look!](https://discourse.julialang.org/t/sublime-text-3-worth-a-look/17142)

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**Author:** [@PetrKryslUCSD](https://discourse.julialang.org/u/PetrKryslUCSD)\
**Replies:** 110\
**Last updated:** [May 12, 2020, 7:42pm UTC](https://discourse.julialang.org/t/sublime-text-3-worth-a-look/17142 "2020-05-12T19:42:57Z")

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The “Tooling” category lists Juno and VS Code explicitly, probably because they are considered general-purpose and widely used (and widely usable?). I believe from my very recent experience that Sublime Text 3 is at leas…

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## [JuliaCon 2020 Update](https://discourse.julialang.org/t/juliacon-2020-update/38876)

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**Author:** [@avik](https://discourse.julialang.org/u/avik)\
**Replies:** 19\
**Last updated:** [May 8, 2020, 2:50pm UTC](https://discourse.julialang.org/t/juliacon-2020-update/38876 "2020-05-08T14:50:27Z")

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Following on from our earlier announcement about going virtual, here are some updates about the new format. JuliaCon is a rather large conference (by number of talks) and so running it online is not trivial. We do want …

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## [Union troubles](https://discourse.julialang.org/t/union-troubles/39340)

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**Author:** [@maarten\_van\_damme](https://discourse.julialang.org/u/maarten_van_damme)\
**Replies:** 7\
**Last updated:** [May 12, 2020, 4:50pm UTC](https://discourse.julialang.org/t/union-troubles/39340 "2020-05-12T16:50:08Z")

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I want to define a type that is effectively a vector of a matrix of operators. However, if the operator has norm zero or is proportional to the identity then we can simplify the necessary operations =\> we want to store t…

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## [Type instability with Dirichlet distribution in Turing](https://discourse.julialang.org/t/type-instability-with-dirichlet-distribution-in-turing/39300)

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**Author:** [@ElOceanografo](https://discourse.julialang.org/u/ElOceanografo)\
**Replies:** 3\
**Last updated:** [May 12, 2020, 4:26pm UTC](https://discourse.julialang.org/t/type-instability-with-dirichlet-distribution-in-turing/39300 "2020-05-12T16:26:52Z")

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I’m fitting a marginalized Gaussian mixture model with Turing, and the sampler is running very slowly. Looking at the output of @code\_warntype, it appears that drawing the mixture weights from a Dirichlet distribution i…

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## [Dictionary with loop and squared numbers](https://discourse.julialang.org/t/dictionary-with-loop-and-squared-numbers/39353)

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**Author:** [@Ancapistola](https://discourse.julialang.org/u/Ancapistola)\
**Replies:** 5\
**Last updated:** [May 12, 2020, 4:18pm UTC](https://discourse.julialang.org/t/dictionary-with-loop-and-squared-numbers/39353 "2020-05-12T16:18:59Z")

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i’m learning Julia through juliaacademy.com and i’m not getting past exercise 4.2. 4.1 I got it easy, but I ended up stalling right away. I’ve tried everything but it didn’t work at all. if anyone can help me i will be…

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## [Very slow pre-compiling and \`using\`of custom Julia package](https://discourse.julialang.org/t/very-slow-pre-compiling-and-using-of-custom-julia-package/24708)

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**Author:** [@CameronBieganek](https://discourse.julialang.org/u/CameronBieganek)\
**Replies:** 3\
**Last updated:** [May 12, 2020, 4:12pm UTC](https://discourse.julialang.org/t/very-slow-pre-compiling-and-using-of-custom-julia-package/24708 "2020-05-12T16:12:10Z")

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I’ve been working on a Julia package at work, call it Unicorns.jl. The package is currently in dev mode. Whenever I make changes to the source and then call using Unicorns (yes, I know about Revise.jl), it takes a very l…

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## [Problem in upgrading Atom to Julia 1.4](https://discourse.julialang.org/t/problem-in-upgrading-atom-to-julia-1-4/38749)

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**Author:** [@Luigi\_Marongiu](https://discourse.julialang.org/u/Luigi_Marongiu)\
**Replies:** 9\
**Last updated:** [May 12, 2020, 4:03pm UTC](https://discourse.julialang.org/t/problem-in-upgrading-atom-to-julia-1-4/38749 "2020-05-12T16:03:10Z")

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I have upgraded to Julia 1.4. On terminal, Julia runs smoothly but on Atom, the packages do not load. If I run using Pkg, for instance, the evaluator remains stuck. What might be the problem? Also, I tried to copy only…

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## [Error when installing PowerModels](https://discourse.julialang.org/t/error-when-installing-powermodels/39320)

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**Author:** [@waeltaha10](https://discourse.julialang.org/u/waeltaha10)\
**Replies:** 1\
**Last updated:** [May 12, 2020, 3:06pm UTC](https://discourse.julialang.org/t/error-when-installing-powermodels/39320 "2020-05-12T15:06:52Z")

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I have just installed Juno and I have a problem with installing the package PowerModels. I’m using windows 10 home 64-bit. The problem is displayed in the next lines (@v1.4) pkg\> test PowerModels Testing PowerModels …

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## [Package Installation Failing April 2020 - JuliaDB, OnlineStats](https://discourse.julialang.org/t/package-installation-failing-april-2020-juliadb-onlinestats/38395)

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**Author:** [@eyedia](https://discourse.julialang.org/u/eyedia)\
**Replies:** 6\
**Last updated:** [May 12, 2020, 3:02pm UTC](https://discourse.julialang.org/t/package-installation-failing-april-2020-juliadb-onlinestats/38395 "2020-05-12T15:02:07Z")

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Seems like error has something to do with JuliaDB, OnlineStats, but not sure. Just execute below code: using Pkg Pkg.add(“CSV”) Pkg.add(“DataFrames”) Pkg.add(“HTTP”) Pkg.add(“JSON”) Pkg.add(“JuliaDB”) Pkg.add(“Mb…

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## [Naming output files from processes spawned using addprocs\_slurm on a cluster](https://discourse.julialang.org/t/naming-output-files-from-processes-spawned-using-addprocs-slurm-on-a-cluster/39174)

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**Author:** [@HarrisonWilde](https://discourse.julialang.org/u/HarrisonWilde)\
**Replies:** 1\
**Last updated:** [May 12, 2020, 2:14pm UTC](https://discourse.julialang.org/t/naming-output-files-from-processes-spawned-using-addprocs-slurm-on-a-cluster/39174 "2020-05-12T14:14:00Z")

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Hi, I am running some distributed code using ClusterManagers.jl’s addprocs\_slurm command to spawn processes after submitting an sbatch script on our cluster’s login node. I can happily rename the output file for the “hea…

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## [Size vs length](https://discourse.julialang.org/t/size-vs-length/37101)

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**Author:** [@isentropic](https://discourse.julialang.org/u/isentropic)\
**Replies:** 13\
**Last updated:** [May 12, 2020, 1:28pm UTC](https://discourse.julialang.org/t/size-vs-length/37101 "2020-05-12T13:28:45Z")

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I wonder why the performance of size is so much faster when it comes to matrices: julia\> a = rand(100,2) 100×2 Array{Float64,2}: 0.47076 0.605881 0.0432887 0.318102 0.12271 0.121367 0.0737559 0.885239 0.389…

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## [How to allow time array to be passed as an input for the parameter p associated with differential equations](https://discourse.julialang.org/t/how-to-allow-time-array-to-be-passed-as-an-input-for-the-parameter-p-associated-with-differential-equations/39346)

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**Author:** [@quantiota](https://discourse.julialang.org/u/quantiota)\
**Replies:** 2\
**Last updated:** [May 12, 2020, 1:06pm UTC](https://discourse.julialang.org/t/how-to-allow-time-array-to-be-passed-as-an-input-for-the-parameter-p-associated-with-differential-equations/39346 "2020-05-12T13:06:01Z")

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hey, i am learning the example it works but i do not know if it is correct. using DifferentialEquations, Plots l = 1.0 # length \[m\] m = 1.0 # mass\[m\] g = 9.8…

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## [Is there any way to speed up Documenter a bit?](https://discourse.julialang.org/t/is-there-any-way-to-speed-up-documenter-a-bit/39345)

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**Author:** [@Xing\_Shi\_Cai](https://discourse.julialang.org/u/Xing_Shi_Cai)\
**Replies:** 2\
**Last updated:** [May 12, 2020, 12:54pm UTC](https://discourse.julialang.org/t/is-there-any-way-to-speed-up-documenter-a-bit/39345 "2020-05-12T12:54:19Z")

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I use Documenter to build a fairly small site with very few pages. But it still takes two and a half minutes for it to finish. This makes fixing things and seeing the change very tedious. Is there a way to speed things u…

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## [How fast can Plots.jl work after being compiled with PackageCompiler?](https://discourse.julialang.org/t/how-fast-can-plots-jl-work-after-being-compiled-with-packagecompiler/39314)

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**Author:** [@Xing\_Shi\_Cai](https://discourse.julialang.org/u/Xing_Shi_Cai)\
**Replies:** 13\
**Last updated:** [May 12, 2020, 12:47pm UTC](https://discourse.julialang.org/t/how-fast-can-plots-jl-work-after-being-compiled-with-packagecompiler/39314 "2020-05-12T12:47:37Z")

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I just tried using PackageComipler on Plots.jl. With precompiled images, I got julia\> @time using Plots 0.891786 seconds (1.26 M allocations: 59.289 MiB, 16.97% gc time) julia\> @time (p = plot(rand(5), rand(5)); disp…

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## [Are packages which I download from GitHub secure?](https://discourse.julialang.org/t/are-packages-which-i-download-from-github-secure/39334)

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**Author:** [@DKad](https://discourse.julialang.org/u/DKad)\
**Replies:** 1\
**Last updated:** [May 12, 2020, 11:49am UTC](https://discourse.julialang.org/t/are-packages-which-i-download-from-github-secure/39334 "2020-05-12T11:49:44Z")

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Noticing strange behaviour of a package in julia, I don’t know which is the culprit: Is the downloading of packages from Github secure? My system is OpenSuse Leap 15.1, my julia has version 1.4.1. After running include…

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## [Parametric type that can "act" as its parameter type](https://discourse.julialang.org/t/parametric-type-that-can-act-as-its-parameter-type/39339)

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**Author:** [@rlrs](https://discourse.julialang.org/u/rlrs)\
**Replies:** 2\
**Last updated:** [May 12, 2020, 11:04am UTC](https://discourse.julialang.org/t/parametric-type-that-can-act-as-its-parameter-type/39339 "2020-05-12T11:04:20Z")

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I’m trying to write a type, let’s call it Hole{T}, which can be assigned to a field of type T in a struct. Is this possible to do? I realize it might be quite weird type-wise, but if my other option is to rewrite all my …

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## [Defining structs inside functions during runtime (versioned structs design? value types?)](https://discourse.julialang.org/t/defining-structs-inside-functions-during-runtime-versioned-structs-design-value-types/39315)

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**Author:** [@tamasgal](https://discourse.julialang.org/u/tamasgal)\
**Replies:** 10\
**Last updated:** [May 12, 2020, 7:58am UTC](https://discourse.julialang.org/t/defining-structs-inside-functions-during-runtime-versioned-structs-design-value-types/39315 "2020-05-12T07:58:30Z")

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I need help (again) with macros. This was driving me crazy today, although I found quite a few “related” posts, nothing worked to achieve what I want so I start to think that I am working on a horribly bad design. I deci…

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## [ConstraintSolver Series](https://discourse.julialang.org/t/constraintsolver-series/39335)

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**Author:** [@Wikunia](https://discourse.julialang.org/u/Wikunia)\
**Replies:** 1\
**Last updated:** [May 12, 2020, 9:30am UTC](https://discourse.julialang.org/t/constraintsolver-series/39335 "2020-05-12T09:30:40Z")

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Just found out about the blog-post tag :smiley: Some of you might have seen this already but maybe it’s something new for others who are interested in this kinda stuff. I’ve started to create a sudoku solver back in Se…

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## [Let julia return default Int32 or Float32-type data?](https://discourse.julialang.org/t/let-julia-return-default-int32-or-float32-type-data/39331)

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**Author:** [@bigdataman2015](https://discourse.julialang.org/u/bigdataman2015)\
**Replies:** 1\
**Last updated:** [May 12, 2020, 9:18am UTC](https://discourse.julialang.org/t/let-julia-return-default-int32-or-float32-type-data/39331 "2020-05-12T09:18:27Z")

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x = \[1, 2, 3\]; typeof(x) always return Vector{Int64}; y = 1.0; typeof(y) always return Float64; myfunc(my\_param) always return Int64 or Float64; … … is it possible to make a global setting to make sure every evaluati…

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## [Linprog and Clp under JuMP or MathOptInterface - Why is it so hard?](https://discourse.julialang.org/t/linprog-and-clp-under-jump-or-mathoptinterface-why-is-it-so-hard/39323)

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**Author:** [@scotts](https://discourse.julialang.org/u/scotts)\
**Replies:** 2\
**Last updated:** [May 12, 2020, 8:33am UTC](https://discourse.julialang.org/t/linprog-and-clp-under-jump-or-mathoptinterface-why-is-it-so-hard/39323 "2020-05-12T08:33:19Z")

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Julia is working beautifully on an LP problem on my mac. My optimisation problem is structured with inequality constraints and the sense vector: sol = linprog(-f,A,sense,b,lb,ub,ClpSolver()) For some reason running t…

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## [Timing Clebsch-Gordan-coefficients calls in Julia (beating c++ again)](https://discourse.julialang.org/t/timing-clebsch-gordan-coefficients-calls-in-julia-beating-c-again/32736)

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**Author:** [@misha\_mikhasenko](https://discourse.julialang.org/u/misha_mikhasenko)\
**Replies:** 7\
**Last updated:** [May 12, 2020, 8:45am UTC](https://discourse.julialang.org/t/timing-clebsch-gordan-coefficients-calls-in-julia-beating-c-again/32736 "2020-05-12T08:45:34Z")

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I have compared 4 different implementations of the Clebsch-Gordan coefficients freshly coded in my ThreeBodyDecay.jl package from GSL.jl call (c++ implementation) from SymPy.jl (for the sake of completeness) julia pac…

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## [Sparse matrix and zero pivots](https://discourse.julialang.org/t/sparse-matrix-and-zero-pivots/39332)

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**Author:** [@Mirsad\_Cosovic](https://discourse.julialang.org/u/Mirsad_Cosovic)\
**Replies:** 2\
**Last updated:** [May 12, 2020, 8:24am UTC](https://discourse.julialang.org/t/sparse-matrix-and-zero-pivots/39332 "2020-05-12T08:24:20Z")

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I have a large sparse matrix and I need to find a position of zero pivots, so my matrix is singular. Standard QR factorization for dense matrices without permutations gives the result that I need, the pivots are on the m…

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## [Regression Workflow](https://discourse.julialang.org/t/regression-workflow/39071)

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**Author:** [@IljaK91](https://discourse.julialang.org/u/IljaK91)\
**Replies:** 6\
**Last updated:** [May 12, 2020, 7:36am UTC](https://discourse.julialang.org/t/regression-workflow/39071 "2020-05-12T07:36:27Z")

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Hi everyone, So far I did not succeed in moving my empirical workflow to Julia: Data cleaning (Query.jl/DataFrames.jl) → Regression (GLM.jl) → Custom Standard Errors (CovarianceMatrices.jl) ??? Latex-Regressiontable (R…

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## [An unexpected result using DataFrames.jl](https://discourse.julialang.org/t/an-unexpected-result-using-dataframes-jl/39249)

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**Author:** [@ameresv](https://discourse.julialang.org/u/ameresv)\
**Replies:** 12\
**Last updated:** [May 12, 2020, 6:08am UTC](https://discourse.julialang.org/t/an-unexpected-result-using-dataframes-jl/39249 "2020-05-12T06:08:52Z")

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Hi! Following JuliaAcademy, I had found something that results confusing. using DataFrames, Random function sim\_e() draw = Float64\[\] while true push!(draw, rand()) sum(draw) \> 1.0 && return draw…

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