# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1652

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

**Page:** 1653

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## [ANN: Exfiltrator](https://discourse.julialang.org/t/ann-exfiltrator/44455)

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**Author:** [@antoine-levitt](https://discourse.julialang.org/u/antoine-levitt)\
**Replies:** 16\
**Last updated:** [August 21, 2020, 8:26pm UTC](https://discourse.julialang.org/t/ann-exfiltrator/44455 "2020-08-21T20:26:43Z")

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Exfiltrator (https://github.com/antoine-levitt/Exfiltrator.jl) is Infiltrator’s younger sibling. It exfiltrates local variables to the global scope for easier exploration in the REPL. Example from the readme: using Exfi…

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## [Non-negative ODE solution](https://discourse.julialang.org/t/non-negative-ode-solution/23449)

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**Author:** [@dg.aragones](https://discourse.julialang.org/u/dg.aragones)\
**Replies:** 5\
**Last updated:** [August 21, 2020, 7:53pm UTC](https://discourse.julialang.org/t/non-negative-ode-solution/23449 "2020-08-21T19:53:36Z")

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Is there any Julia option equivalent to “Nonnegative” in “odeset” in Matlab? Here is the documentation about the function I’m talking about: I think it’s a very useful function and it’d be nice to have something simi…

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## [Usage of \`@eval\` in Base code when defining a NamedTuple constructor](https://discourse.julialang.org/t/usage-of-eval-in-base-code-when-defining-a-namedtuple-constructor/45328)

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**Author:** [@CameronBieganek](https://discourse.julialang.org/u/CameronBieganek)\
**Replies:** 5\
**Last updated:** [August 21, 2020, 6:52pm UTC](https://discourse.julialang.org/t/usage-of-eval-in-base-code-when-defining-a-namedtuple-constructor/45328 "2020-08-21T18:52:46Z")

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Can anyone explain to me what is going on in this chunk of code from Base? @eval function NamedTuple{names,T}(args::Tuple) where {names, T \<: Tuple} if length(args) != length(names::Tuple) throw(ArgumentErro…

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## [Plots colorbar doesn't scale with pgfplots backend](https://discourse.julialang.org/t/plots-colorbar-doesnt-scale-with-pgfplots-backend/45283)

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**Author:** [@scone](https://discourse.julialang.org/u/scone)\
**Replies:** 2\
**Last updated:** [August 21, 2020, 6:06pm UTC](https://discourse.julialang.org/t/plots-colorbar-doesnt-scale-with-pgfplots-backend/45283 "2020-08-21T18:06:13Z")

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Hello everyone, I just developed a new issue I wasn’t having before. I updated my packages a few days ago, and now when I scatterplot, the color bar is locked to the interval \[0,1\] for some reason. For example: usi…

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## [Failure to add IJulia in Julia 1.50](https://discourse.julialang.org/t/failure-to-add-ijulia-in-julia-1-50/45321)

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**Author:** [@Ramiro\_Bravo](https://discourse.julialang.org/u/Ramiro_Bravo)\
**Replies:** 1\
**Last updated:** [August 21, 2020, 4:35pm UTC](https://discourse.julialang.org/t/failure-to-add-ijulia-in-julia-1-50/45321 "2020-08-21T16:35:01Z")

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I am trying to add Jupyterlab to my installation of Julia 1.50. When I type add IJulia inside the package manager, the installation process crashes Julia and takes me back to the Ubuntu shell. The final message is “Illeg…

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## [Help with a shell command](https://discourse.julialang.org/t/help-with-a-shell-command/45312)

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**Author:** [@Joachim\_Dahl](https://discourse.julialang.org/u/Joachim_Dahl)\
**Replies:** 3\
**Last updated:** [August 21, 2020, 1:59pm UTC](https://discourse.julialang.org/t/help-with-a-shell-command/45312 "2020-08-21T13:59:07Z")

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I am trying to construct a shell command for running $ python3 script.py X=“a b c” Here’s what I tried: julia\> args = \["script.py", "X=\\"a b c\\""\] 2-element Array{String,1}: "script.py" "X=\\"a b c\\"" julia\> cmd =…

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## [Deep-equal](https://discourse.julialang.org/t/deep-equal/45315)

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**Author:** [@cstjean](https://discourse.julialang.org/u/cstjean)\
**Replies:** 7\
**Last updated:** [August 21, 2020, 3:37pm UTC](https://discourse.julialang.org/t/deep-equal/45315 "2020-08-21T15:37:25Z")

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We have deepcopy, which recursively copies the object down to its “atoms”. Has anyone written the corresponding deepequal, such that deepequal(deepcopy(x), deepcopy(x)) == true?

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## [Scalar getindex during Flux gradient computation](https://discourse.julialang.org/t/scalar-getindex-during-flux-gradient-computation/45325)

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**Author:** [@HenriDeh](https://discourse.julialang.org/u/HenriDeh)\
**Replies:** 0\
**Last updated:** [August 21, 2020, 3:34pm UTC](https://discourse.julialang.org/t/scalar-getindex-during-flux-gradient-computation/45325 "2020-08-21T15:34:47Z")

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I have a issue with a GPU scalar getindex during gradient computation with Flux. Problem is, I just can’t reproduce the problem with a simpler MWE. I swear I tried so hard. So here’s a chunk of the code and what I unders…

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## [Your Julia language journey](https://discourse.julialang.org/t/your-julia-language-journey/45241)

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**Author:** [@JaydevSR](https://discourse.julialang.org/u/JaydevSR)\
**Replies:** 5\
**Last updated:** [August 21, 2020, 12:11pm UTC](https://discourse.julialang.org/t/your-julia-language-journey/45241 "2020-08-21T12:11:38Z")

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I have been learning Julia for a few months now and want to know how others have walked this path before. Please share how you started learning Julia, the difficulties you faced, and other interesting things you did whil…

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## [Ordered arrays](https://discourse.julialang.org/t/ordered-arrays/45258)

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**Author:** [@mamo](https://discourse.julialang.org/u/mamo)\
**Replies:** 4\
**Last updated:** [August 21, 2020, 11:55am UTC](https://discourse.julialang.org/t/ordered-arrays/45258 "2020-08-21T11:55:49Z")

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If I have a Dict: P=Dict(“F1”=\>(“a30”, “a37”), “F2”=\>(“a10”, “a11”, “a12”), “F3”=\>(“a15”, “a22”, “a31”)) how to make it ordered - when it is used to be used by order - F1,F2,F3…? Thank you! Marco

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## [How to make LoopVectorization work with computing Euclidean distance for every column?](https://discourse.julialang.org/t/how-to-make-loopvectorization-work-with-computing-euclidean-distance-for-every-column/45307)

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**Author:** [@xiaodai](https://discourse.julialang.org/u/xiaodai)\
**Replies:** 13\
**Last updated:** [August 21, 2020, 11:06am UTC](https://discourse.julialang.org/t/how-to-make-loopvectorization-work-with-computing-euclidean-distance-for-every-column/45307 "2020-08-21T11:06:12Z")

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Consider the below. The code works but when I add @avx it gives error true && (view)(a, :, i) ERROR: "Expression not recognized." Stacktrace: \[1\] add\_operation!(::LoopVectorization.LoopSet, ::Symbol, ::Expr, ::Int64, :…

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## [Error in ploting](https://discourse.julialang.org/t/error-in-ploting/45137)

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**Author:** [@Nithin\_M](https://discourse.julialang.org/u/Nithin_M)\
**Replies:** 28\
**Last updated:** [August 21, 2020, 10:31am UTC](https://discourse.julialang.org/t/error-in-ploting/45137 "2020-08-21T10:31:07Z")

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## [Smooth delta functions to compute Jacobian and Hessian from samples](https://discourse.julialang.org/t/smooth-delta-functions-to-compute-jacobian-and-hessian-from-samples/45282)

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**Author:** [@mleprovost](https://discourse.julialang.org/u/mleprovost)\
**Replies:** 10\
**Last updated:** [August 21, 2020, 10:16am UTC](https://discourse.julialang.org/t/smooth-delta-functions-to-compute-jacobian-and-hessian-from-samples/45282 "2020-08-21T10:16:18Z")

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Hello, Given an expensive function \\boldsymbol{G} :\\mathbb{R}^n \\xrightarrow{} \\mathbb{R}^m whose value is known at samples \\boldsymbol{x}^1,\\ldots, \\boldsymbol{x}^N, I would like to compute the Jacobian and Hessian a…

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## [Multi-threading changing results](https://discourse.julialang.org/t/multi-threading-changing-results/44671)

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**Author:** [@Joao\_Barata](https://discourse.julialang.org/u/Joao_Barata)\
**Replies:** 18\
**Last updated:** [August 21, 2020, 6:51am UTC](https://discourse.julialang.org/t/multi-threading-changing-results/44671 "2020-08-21T06:51:28Z")

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Hello, I’m doing some parallel loops in my code using multi-threading. As I was reviewing my results, I noticed that I kept having different results in a piece of code, although the input data was always the same. So in…

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## [ERROR: UndefVarError: Compiler not defined](https://discourse.julialang.org/t/error-undefvarerror-compiler-not-defined/45142)

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**Author:** [@colintbowers](https://discourse.julialang.org/u/colintbowers)\
**Replies:** 7\
**Last updated:** [August 21, 2020, 4:52am UTC](https://discourse.julialang.org/t/error-undefvarerror-compiler-not-defined/45142 "2020-08-21T04:52:49Z")

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Hi all, I’m getting the following error: ERROR: UndefVarError: Compiler not defined Stacktrace: \[1\] collect\_to\_with\_first! at ./array.jl:689 \[inlined\] \[2\] collect(::Base.Generator{UnitRange{Int64},IGGen.var"#126#127"…

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## [Query.jl: collect's return type is not as expected](https://discourse.julialang.org/t/query-jl-collects-return-type-is-not-as-expected/45278)

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**Author:** [@kai](https://discourse.julialang.org/u/kai)\
**Replies:** 3\
**Last updated:** [August 21, 2020, 4:10am UTC](https://discourse.julialang.org/t/query-jl-collects-return-type-is-not-as-expected/45278 "2020-08-21T04:10:57Z")

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Hello, here’s something I don’t understand about Query.jl: After running a few query commands and calling collect, I was expecting the result to be of type Array{MyObs{Float64}, 1}, but got Array{MyObs,1} instead. When I…

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## [One trick to get to background-only threads](https://discourse.julialang.org/t/one-trick-to-get-to-background-only-threads/33175)

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**Author:** [@tro3](https://discourse.julialang.org/u/tro3)\
**Replies:** 3\
**Last updated:** [August 21, 2020, 3:22am UTC](https://discourse.julialang.org/t/one-trick-to-get-to-background-only-threads/33175 "2020-08-21T03:22:19Z")

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Currently in the v1.3(.1) threading implementation, tasks are assigned to a random thread, and that thread might be the primary thread. This can be problematic in a couple of use cases, for example a GUI that suddenly s…

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## [RigidBodyDynamics visualization not working](https://discourse.julialang.org/t/rigidbodydynamics-visualization-not-working/45232)

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**Author:** [@\_dominic](https://discourse.julialang.org/u/_dominic)\
**Replies:** 6\
**Last updated:** [August 21, 2020, 3:06am UTC](https://discourse.julialang.org/t/rigidbodydynamics-visualization-not-working/45232 "2020-08-21T03:06:45Z")

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I am playing with the example from the RigidBodyDynamic.jl documentation with the MeshCatMechanisms.jl. No major changes. How do I get the last link to show? using RigidBodyDynamics using LinearAlgebra using StaticArra…

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## [Importing SharedArray module](https://discourse.julialang.org/t/importing-sharedarray-module/44953)

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**Author:** [@trathi](https://discourse.julialang.org/u/trathi)\
**Replies:** 1\
**Last updated:** [August 21, 2020, 2:43am UTC](https://discourse.julialang.org/t/importing-sharedarray-module/44953 "2020-08-21T02:43:31Z")

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I understand that we need @everywhere before any functions or modules that we want to make available to all the processes. My question is if need to have @everywhere before importing the SharedArrays module as well, i.e…

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## [Blog Post: Ray Tracing Algebraic Surfaces](https://discourse.julialang.org/t/blog-post-ray-tracing-algebraic-surfaces/45298)

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**Author:** [@philzook58](https://discourse.julialang.org/u/philzook58)\
**Replies:** 0\
**Last updated:** [August 21, 2020, 2:38am UTC](https://discourse.julialang.org/t/blog-post-ray-tracing-algebraic-surfaces/45298 "2020-08-21T02:38:58Z")

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I had a fun idea for a blog post using the Julia polynomials ecosystem that I thought I’d share. Came out pretty cute I thought.

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## [JuliaDB, dataframes: Speculations over the future of data packages](https://discourse.julialang.org/t/juliadb-dataframes-speculations-over-the-future-of-data-packages/14012)

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**Author:** [@DominiqueMakowski](https://discourse.julialang.org/u/DominiqueMakowski)\
**Replies:** 24\
**Last updated:** [August 21, 2020, 2:11am UTC](https://discourse.julialang.org/t/juliadb-dataframes-speculations-over-the-future-of-data-packages/14012 "2020-08-21T02:11:53Z")

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It is kinda unsettling for newcomers (at least those that are used to R or pandas) to see that there are different data-storage packages with the same goal, such as dataframes or JuliaDB, since many other packages depend…

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## [Experienced software guy for hire](https://discourse.julialang.org/t/experienced-software-guy-for-hire/45290)

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**Author:** [@a5vzener](https://discourse.julialang.org/u/a5vzener)\
**Replies:** 3\
**Last updated:** [August 21, 2020, 1:15am UTC](https://discourse.julialang.org/t/experienced-software-guy-for-hire/45290 "2020-08-21T01:15:55Z")

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Hello all, Please allow me to announce that I am available for hire as a Julia-enabled developer and software architect. I have 20+ years experience as a Java, Ruby and now Julia developer as well as mid- and senior-lev…

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## [How to properly define a function with changeable parameters within a struct?](https://discourse.julialang.org/t/how-to-properly-define-a-function-with-changeable-parameters-within-a-struct/45292)

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**Author:** [@RuckerC](https://discourse.julialang.org/u/RuckerC)\
**Replies:** 4\
**Last updated:** [August 21, 2020, 1:12am UTC](https://discourse.julialang.org/t/how-to-properly-define-a-function-with-changeable-parameters-within-a-struct/45292 "2020-08-21T01:12:51Z")

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Is there a way to define a function within a struct such that the function depends on some of the other fields in the struct? For example, I currently have mutable struct Net a::Float64 b::Float64 f::Function end f…

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## [Why sum of the measured times of each function is not equal to the total run time?](https://discourse.julialang.org/t/why-sum-of-the-measured-times-of-each-function-is-not-equal-to-the-total-run-time/45261)

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**Author:** [@Nova](https://discourse.julialang.org/u/Nova)\
**Replies:** 20\
**Last updated:** [August 21, 2020, 12:47am UTC](https://discourse.julialang.org/t/why-sum-of-the-measured-times-of-each-function-is-not-equal-to-the-total-run-time/45261 "2020-08-21T00:47:03Z")

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Here is the code. I’m just providing the code to executed and observe the issue that I am talking about. A= sparse(\[0 1 0 1;1 0 1 0;0 1 0 0;1 0 0 0\]) sm\_vec = rand(4, 5) k = 3 function Filter(sm\_vec, k, A) @time …

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## [CUDA matmul performance](https://discourse.julialang.org/t/cuda-matmul-performance/45267)

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**Author:** [@acxz](https://discourse.julialang.org/u/acxz)\
**Replies:** 11\
**Last updated:** [August 21, 2020, 12:42am UTC](https://discourse.julialang.org/t/cuda-matmul-performance/45267 "2020-08-21T00:42:22Z")

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Hello everyone, I have recently been trying to GPUify my code. I first tried replacing my CPU Arrays with CuArrays as recommended, however, that resulted in a slower program execution time. So I’m trying to dig a bit d…

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## [Is there a Julia equivalent of scipy.optimize.minimize(method='TNC')?](https://discourse.julialang.org/t/is-there-a-julia-equivalent-of-scipy-optimize-minimize-method-tnc/45154)

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**Author:** [@liuyxpp](https://discourse.julialang.org/u/liuyxpp)\
**Replies:** 23\
**Last updated:** [August 21, 2020, 12:12am UTC](https://discourse.julialang.org/t/is-there-a-julia-equivalent-of-scipy-optimize-minimize-method-tnc/45154 "2020-08-21T00:12:52Z")

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which is a truncated Newton (TNC) algorithm, see here for details: minimize(method=’TNC’) — SciPy v1.9.1 Manual. I have a box constrained optimization problem which requires more evaluations with Optim.jl + BFGS (or any…

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## [Please don't use "Taking ... seriously" as a topic name](https://discourse.julialang.org/t/please-dont-use-taking-seriously-as-a-topic-name/45207)

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**Author:** [@fabiangans](https://discourse.julialang.org/u/fabiangans)\
**Replies:** 17\
**Last updated:** [August 20, 2020, 10:51pm UTC](https://discourse.julialang.org/t/please-dont-use-taking-seriously-as-a-topic-name/45207 "2020-08-20T22:51:17Z")

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A very popular topic title on this forum seems to be “Taking ABC seriously”, just use the search on this forum and enter “Taking seriously” and you will see a large list. Although a lot of interesting and fruitful discus…

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## [\[ANN\] EvoTrees.jl: experimental GPU support for gradient boosting trees](https://discourse.julialang.org/t/ann-evotrees-jl-experimental-gpu-support-for-gradient-boosting-trees/44726)

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**Author:** [@jeremiedb](https://discourse.julialang.org/u/jeremiedb)\
**Replies:** 4\
**Last updated:** [August 20, 2020, 10:14pm UTC](https://discourse.julialang.org/t/ann-evotrees-jl-experimental-gpu-support-for-gradient-boosting-trees/44726 "2020-08-20T22:14:40Z")

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Starting with v0.5.0, it’s now possible to build GBT models on GPU, thanks to the underlying CUDA.jl package providing nimble tools to handle kernels. Speedups are modest compared to those observed with XGBoost’s gpu\_his…

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## [Tranducers.jl's \`Filter\` is slow simple cases. When to use Transducers?](https://discourse.julialang.org/t/tranducers-jls-filter-is-slow-simple-cases-when-to-use-transducers/45247)

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**Author:** [@xiaodai](https://discourse.julialang.org/u/xiaodai)\
**Replies:** 1\
**Last updated:** [August 20, 2020, 10:13pm UTC](https://discourse.julialang.org/t/tranducers-jls-filter-is-slow-simple-cases-when-to-use-transducers/45247 "2020-08-20T22:13:33Z")

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Transducers.jl have lots of functionality but I it’s not clear WHEN I use it as in when can I expect a speed up and what operations can be done in parallel. See using Transducers x = rand(Int, 100\_000\_000) f(x) = x |\>…

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## [Passing a pointer to struct of arrays and bitfields to ccall](https://discourse.julialang.org/t/passing-a-pointer-to-struct-of-arrays-and-bitfields-to-ccall/45254)

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**Author:** [@pauljurczak](https://discourse.julialang.org/u/pauljurczak)\
**Replies:** 11\
**Last updated:** [August 20, 2020, 2:10pm UTC](https://discourse.julialang.org/t/passing-a-pointer-to-struct-of-arrays-and-bitfields-to-ccall/45254 "2020-08-20T14:10:11Z")

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I still can’t figure out memory layout of Julia data structures. I have: mutable struct Stimuli rgb::Array{UInt8, 1} depth::Array{Float32, 1} batteryLevel::Float32 end const N = 10^6 stimuli = Stimuli(zeros(UInt…

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