# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1464

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

**Page:** 1465

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## [Is there a many to one dictionary shorthand?](https://discourse.julialang.org/t/is-there-a-many-to-one-dictionary-shorthand/56837)

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**Author:** [@Lincoln\_Hannah](https://discourse.julialang.org/u/Lincoln_Hannah)\
**Replies:** 4\
**Last updated:** [March 10, 2021, 10:18pm UTC](https://discourse.julialang.org/t/is-there-a-many-to-one-dictionary-shorthand/56837 "2021-03-10T22:18:09Z")

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Consider this named tuple, which could also be written as a dictionary (a = 1, b = 1, c = 2, d = 2) Is there a shorthand to group keys with the same value eg? ( (a,b) = 1, (c,d) = 2) Could use an if - in statement.…

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## [Where does Julia (ecosystem) provide the greatest speedup, and where does it lag the most behind (compared to e.g. Python)?](https://discourse.julialang.org/t/where-does-julia-ecosystem-provide-the-greatest-speedup-and-where-does-it-lag-the-most-behind-compared-to-e-g-python/56565)

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**Author:** [@Palli](https://discourse.julialang.org/u/Palli)\
**Replies:** 44\
**Last updated:** [March 10, 2021, 9:43pm UTC](https://discourse.julialang.org/t/where-does-julia-ecosystem-provide-the-greatest-speedup-and-where-does-it-lag-the-most-behind-compared-to-e-g-python/56565 "2021-03-10T21:43:41Z")

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A. First on where Julia is ahead: \[EDIT: What are the greatest Julia (public) package success-stories, with speed-up factors? Feel free to also mention your proprietary non-public success…\] At best the speed is compara…

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## [Update Makie plot in a loop](https://discourse.julialang.org/t/update-makie-plot-in-a-loop/56911)

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**Author:** [@rveltz](https://discourse.julialang.org/u/rveltz)\
**Replies:** 6\
**Last updated:** [March 10, 2021, 9:06pm UTC](https://discourse.julialang.org/t/update-makie-plot-in-a-loop/56911 "2021-03-10T21:06:09Z")

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Hi, I am looking for the equivalent of Plots.display() to update a plot in Atom Juno for example during a computation. I was suggested AbstractPlotting.inline!(false) but it did not seem to work. Thank you for your hel…

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## [Possible bug in KrylovKit.eigsolve](https://discourse.julialang.org/t/possible-bug-in-krylovkit-eigsolve/55962)

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**Author:** [@iamsuddhasattwa](https://discourse.julialang.org/u/iamsuddhasattwa)\
**Replies:** 11\
**Last updated:** [March 10, 2021, 8:36pm UTC](https://discourse.julialang.org/t/possible-bug-in-krylovkit-eigsolve/55962 "2021-03-10T20:36:06Z")

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I am trying to find the first 4 eigenvalues of a symmetric 8X8 matrix, arranged in increasing order of real part. Symmetry means that the eigenvalues are real. Moreover, as you will see from the output, it is a block dia…

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## [Question about write.to.file with .lp (JuMP context)](https://discourse.julialang.org/t/question-about-write-to-file-with-lp-jump-context/56892)

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**Author:** [@felcbd](https://discourse.julialang.org/u/felcbd)\
**Replies:** 1\
**Last updated:** [March 10, 2021, 7:40pm UTC](https://discourse.julialang.org/t/question-about-write-to-file-with-lp-jump-context/56892 "2021-03-10T19:40:35Z")

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Hi everyone, I had a question about a practice case I actually have with the write.to.file function. I have my model writed with JuMP and I want to solve it with CPLEX directly from my .jl file with !optimize, and I ha…

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## [Help with GLM logistic regression](https://discourse.julialang.org/t/help-with-glm-logistic-regression/56899)

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**Author:** [@jonjilla](https://discourse.julialang.org/u/jonjilla)\
**Replies:** 4\
**Last updated:** [March 10, 2021, 7:01pm UTC](https://discourse.julialang.org/t/help-with-glm-logistic-regression/56899 "2021-03-10T19:01:21Z")

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Can someone help me with using GLM for logistic regression. I’m testing this out on the iris dataset. using RDatasets iris = dataset("datasets","iris") I’ve worked with this before and know that the PetalLength is a …

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## [Precompilation conflicts between Symbolics and ModelingToolkit while installing DifferentialEquations](https://discourse.julialang.org/t/precompilation-conflicts-between-symbolics-and-modelingtoolkit-while-installing-differentialequations/56869)

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**Author:** [@jishnub](https://discourse.julialang.org/u/jishnub)\
**Replies:** 2\
**Last updated:** [March 10, 2021, 5:50pm UTC](https://discourse.julialang.org/t/precompilation-conflicts-between-symbolics-and-modelingtoolkit-while-installing-differentialequations/56869 "2021-03-10T17:50:36Z")

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While precompiling DifferentialEquations in a new environment, I encounter the following warnings: (NewEnv) pkg\> add DifferentialEquations Resolving package versions... Updating \`~/NewEnv/Project.toml\` \[0c46a032\] + …

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## [Hot restart of the main loop when the source code changes](https://discourse.julialang.org/t/hot-restart-of-the-main-loop-when-the-source-code-changes/38840)

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**Author:** [@waralex](https://discourse.julialang.org/u/waralex)\
**Replies:** 5\
**Last updated:** [March 10, 2021, 5:43pm UTC](https://discourse.julialang.org/t/hot-restart-of-the-main-loop-when-the-source-code-changes/38840 "2021-03-10T17:43:30Z")

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Hi, everybody! I’m currently working on the Julia backend for Plotly Dash and I’m faced with the following task. In Python and R, Dash has the following feature: if the server is running in debug mode, changes to the ap…

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## [How to release memory from jupyter notebook?](https://discourse.julialang.org/t/how-to-release-memory-from-jupyter-notebook/56886)

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**Author:** [@bharland](https://discourse.julialang.org/u/bharland)\
**Replies:** 6\
**Last updated:** [March 10, 2021, 5:33pm UTC](https://discourse.julialang.org/t/how-to-release-memory-from-jupyter-notebook/56886 "2021-03-10T17:33:21Z")

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Here is a minimal example that reproduces my problem on a new JupyterLab kernel: x = rand(2^29); varinfo() shows the 4.00 Gb size of ‘x’. But x = nothing does not release this memory. varinfo shows that it is indee…

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## [Is there a Function type which captures its return type](https://discourse.julialang.org/t/is-there-a-function-type-which-captures-its-return-type/56890)

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**Author:** [@feanor12](https://discourse.julialang.org/u/feanor12)\
**Replies:** 4\
**Last updated:** [March 10, 2021, 4:08pm UTC](https://discourse.julialang.org/t/is-there-a-function-type-which-captures-its-return-type/56890 "2021-03-10T16:08:38Z")

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I have a struct which should contain a parametrized function returning a certain type. Can I impose this type restriction onto the struct field? using Unitful struct a T::Function # This will allow any function end o…

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## [Non-english discussion section?](https://discourse.julialang.org/t/non-english-discussion-section/56268)

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**Author:** [@lmiq](https://discourse.julialang.org/u/lmiq)\
**Replies:** 38\
**Last updated:** [March 10, 2021, 3:59pm UTC](https://discourse.julialang.org/t/non-english-discussion-section/56268 "2021-03-10T15:59:26Z")

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@mbauman Do you think there could be a “Multilingual” category where we could automatically move posts like this? Many of us can answer questions from people in other languages (I suppose they don’t feel comfortable e…

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## [SharedArray undefined on worker](https://discourse.julialang.org/t/sharedarray-undefined-on-worker/36926)

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**Author:** [@Paul\_McVay](https://discourse.julialang.org/u/Paul_McVay)\
**Replies:** 7\
**Last updated:** [March 10, 2021, 3:57pm UTC](https://discourse.julialang.org/t/sharedarray-undefined-on-worker/36926 "2021-03-10T15:57:38Z")

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I have what I thought was a really basic usage of SharedArrays. But it says the array is undefined on the worker processes and I have no idea why it would be. I have the following code in a file “test.jl”. I run it with j…

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## [Spectral acceleration](https://discourse.julialang.org/t/spectral-acceleration/56895)

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**Author:** [@Frederic\_Gilt](https://discourse.julialang.org/u/Frederic_Gilt)\
**Replies:** 0\
**Last updated:** [March 10, 2021, 3:52pm UTC](https://discourse.julialang.org/t/spectral-acceleration/56895 "2021-03-10T15:52:50Z")

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Dear community, I have accelerations ai during each time step ti for a given time range \[ai ti\] as raw datas and was wondering if Julia has some already prepared spectral acceleration tool… If not I have a pseudo-code …

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## [Julia: a post-mortem](https://discourse.julialang.org/t/julia-a-post-mortem/56809)

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**Author:** [@mashgholam](https://discourse.julialang.org/u/mashgholam)\
**Replies:** 67\
**Last updated:** [March 10, 2021, 3:46pm UTC](https://discourse.julialang.org/t/julia-a-post-mortem/56809 "2021-03-10T15:46:54Z")

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I have been interested in Julia for some time and I wanted to use it in part of my work. I have been learning it with the help of resources such as the courses available at Julia Academy. Reading a post a few days ago ma…

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## [ForwardDiff evaluation of objective in Optim returns wrong result (objective uses DifferentialEquations pkg)](https://discourse.julialang.org/t/forwarddiff-evaluation-of-objective-in-optim-returns-wrong-result-objective-uses-differentialequations-pkg/54624)

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**Author:** [@moesphere](https://discourse.julialang.org/u/moesphere)\
**Replies:** 7\
**Last updated:** [March 10, 2021, 3:38pm UTC](https://discourse.julialang.org/t/forwarddiff-evaluation-of-objective-in-optim-returns-wrong-result-objective-uses-differentialequations-pkg/54624 "2021-03-10T15:38:52Z")

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I am having a strange problem with ForwardDiff that is internally used in Optim. The minimum returned by Optim is not the same value as the value of the objective function when the minimizer returned by Optim is used, se…

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## [Function definition throwing UndefVarError](https://discourse.julialang.org/t/function-definition-throwing-undefvarerror/56845)

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**Author:** [@MattWillFlood](https://discourse.julialang.org/u/MattWillFlood)\
**Replies:** 2\
**Last updated:** [March 10, 2021, 3:34pm UTC](https://discourse.julialang.org/t/function-definition-throwing-undefvarerror/56845 "2021-03-10T15:34:20Z")

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Hello, I have a function which follows the condensed, simplified format shown below. using Statistics: std, mean, median, var function foo(a,b,c) """ Do some stuff """ if a \> 0 if a == 1 bar(x) = std(x, c…

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## [Delete all rows contained in a dataframe, as specified by an array of ids](https://discourse.julialang.org/t/delete-all-rows-contained-in-a-dataframe-as-specified-by-an-array-of-ids/56874)

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**Author:** [@Nash](https://discourse.julialang.org/u/Nash)\
**Replies:** 3\
**Last updated:** [March 10, 2021, 2:32pm UTC](https://discourse.julialang.org/t/delete-all-rows-contained-in-a-dataframe-as-specified-by-an-array-of-ids/56874 "2021-03-10T14:32:42Z")

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Using ids = findall(nonunique(mydata)) I have found the ids of all rows that are duplicates. Now, I want to clean mydata by erasing the duplicate rows. How is that done?

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## [Why is this a matching error?](https://discourse.julialang.org/t/why-is-this-a-matching-error/56882)

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**Author:** [@HenriDeh](https://discourse.julialang.org/u/HenriDeh)\
**Replies:** 4\
**Last updated:** [March 10, 2021, 2:14pm UTC](https://discourse.julialang.org/t/why-is-this-a-matching-error/56882 "2021-03-10T14:14:08Z")

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Hi, I’m facing this matching error but I simply don’t see why this is not matching… pull!(item, item2 =\> 10) MethodError: no method matching pull!(::Item{Float64,Dirac{Float64},linear\_holding\_cost{Float64}}, ::Pair{Ite…

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## [Where is lufact()?](https://discourse.julialang.org/t/where-is-lufact/56881)

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**Author:** [@compleat](https://discourse.julialang.org/u/compleat)\
**Replies:** 4\
**Last updated:** [March 10, 2021, 1:59pm UTC](https://discourse.julialang.org/t/where-is-lufact/56881 "2021-03-10T13:59:49Z")

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Hi All. Apologies for this, but after 2 years of Julia usage, I still feel like a ‘newbie’ sometimes. I see reference all over the place to ‘lufact()’ but I have tried adding package after package (LinearAlgebra, LinAl…

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## [Slowness of fieldnames and propertynames](https://discourse.julialang.org/t/slowness-of-fieldnames-and-propertynames/55364)

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**Author:** [@Mason](https://discourse.julialang.org/u/Mason)\
**Replies:** 5\
**Last updated:** [March 10, 2021, 12:40pm UTC](https://discourse.julialang.org/t/slowness-of-fieldnames-and-propertynames/55364 "2021-03-10T12:40:03Z")

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So I’ve seen disucssions of this pop up a few times, but I figure it might be good to have a more recent thread here on discourse that we can point people to (and maybe it can motivate a PR / issue to julia) The problem…

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## [FFT planning with flags fails for CUDA](https://discourse.julialang.org/t/fft-planning-with-flags-fails-for-cuda/56870)

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**Author:** [@roflmaostc](https://discourse.julialang.org/u/roflmaostc)\
**Replies:** 2\
**Last updated:** [March 10, 2021, 12:26pm UTC](https://discourse.julialang.org/t/fft-planning-with-flags-fails-for-cuda/56870 "2021-03-10T12:26:30Z")

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Hey, I was trying to do a FFT plan for a CuArray. The following works: julia\> using CUDA, CUDA.CUFFT julia\> x = CUDA.rand(2, 2) 2×2 CuArray{Float32, 2}: 0.318697 0.144699 0.631969 0.433798 julia\> fft(x) 2×2 CuArr…

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## [How to change arrays of a mutable struct](https://discourse.julialang.org/t/how-to-change-arrays-of-a-mutable-struct/56527)

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**Author:** [@DhananjayAshok](https://discourse.julialang.org/u/DhananjayAshok)\
**Replies:** 7\
**Last updated:** [March 10, 2021, 10:48am UTC](https://discourse.julialang.org/t/how-to-change-arrays-of-a-mutable-struct/56527 "2021-03-10T10:48:07Z")

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Hey there, I am currently trying to make a Dataset struct object that has new X and y values to it appended to it over time. This is my set up mutable struct Dataset{T\<:Real} X::AbstractMatrix{T} y::AbstractVect…

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## [Negative binomial layer](https://discourse.julialang.org/t/negative-binomial-layer/56804)

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**Author:** [@lubo](https://discourse.julialang.org/u/lubo)\
**Replies:** 5\
**Last updated:** [March 10, 2021, 10:45am UTC](https://discourse.julialang.org/t/negative-binomial-layer/56804 "2021-03-10T10:45:24Z")

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Hello, I am new to flux and I would appreciate help with implementing custom layer (or maybe custom activation?). Layer is like Dense layer, some inputs and outputs are exactly two neurons: first with NNlib.softplus ac…

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## [IDE eclipse plugin?](https://discourse.julialang.org/t/ide-eclipse-plugin/56836)

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**Author:** [@tonyhur](https://discourse.julialang.org/u/tonyhur)\
**Replies:** 4\
**Last updated:** [March 10, 2021, 10:32am UTC](https://discourse.julialang.org/t/ide-eclipse-plugin/56836 "2021-03-10T10:32:05Z")

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I am new in Julia and would like to work with eclipse. Is there any eclipse plugin available for julia IDE programming? I only found old links to JuliaDT. Is this still working? Thank you Tony

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## [How do I use symbolic variables with Unitful?](https://discourse.julialang.org/t/how-do-i-use-symbolic-variables-with-unitful/56420)

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**Author:** [@NightMachinary](https://discourse.julialang.org/u/NightMachinary)\
**Replies:** 8\
**Last updated:** [March 10, 2021, 10:05am UTC](https://discourse.julialang.org/t/how-do-i-use-symbolic-variables-with-unitful/56420 "2021-03-10T10:05:15Z")

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I am trying to do some basic Physics problems using Julia. I have had some success using Unitful, but I do not know how I can solve problems for general parameters (i.e., get a closed form of the solution in terms of the…

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## [Plot doesn't show up when calling \`x=\`, \`y=\` explicitly](https://discourse.julialang.org/t/plot-doesnt-show-up-when-calling-x-y-explicitly/56851)

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**Author:** [@maxkapur](https://discourse.julialang.org/u/maxkapur)\
**Replies:** 5\
**Last updated:** [March 10, 2021, 10:04am UTC](https://discourse.julialang.org/t/plot-doesnt-show-up-when-calling-x-y-explicitly/56851 "2021-03-10T10:04:58Z")

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Am I wrong for being surprised by this behavior? julia\> using Plots julia\> a = rand(10); b = rand(10); julia\> plot(a, b) # Works julia\> plot(x=a, y=b) # Plots a blank canvas

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## [Check gpu availability on a non-gpu machine with CUDA.jl](https://discourse.julialang.org/t/check-gpu-availability-on-a-non-gpu-machine-with-cuda-jl/56862)

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**Author:** [@kadir-gunel](https://discourse.julialang.org/u/kadir-gunel)\
**Replies:** 1\
**Last updated:** [March 10, 2021, 9:23am UTC](https://discourse.julialang.org/t/check-gpu-availability-on-a-non-gpu-machine-with-cuda-jl/56862 "2021-03-10T09:23:09Z")

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Hello, I need to check the availability of the gpu on the machine - if exists one. How do we check it ? using CUDA CUDA.deviceid() != - 1 ? CuArray : Array But this seems not working with a gpuless computer - the co…

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## [Creation of range along given dimension](https://discourse.julialang.org/t/creation-of-range-along-given-dimension/56747)

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**Author:** [@BambOoxX](https://discourse.julialang.org/u/BambOoxX)\
**Replies:** 5\
**Last updated:** [March 10, 2021, 9:13am UTC](https://discourse.julialang.org/t/creation-of-range-along-given-dimension/56747 "2021-03-10T09:13:42Z")

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I currently have to handle multi-dimensional data, where I have to compute several broadcasting operations with ranges. In 2D I use e.g (1:10) .\* (1:5)' which gives a nice matrix. The first vector is of type UnitRange…

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## [Analog of markevery in Plots.jl?](https://discourse.julialang.org/t/analog-of-markevery-in-plots-jl/10269)

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**Author:** [@gideonsimpson](https://discourse.julialang.org/u/gideonsimpson)\
**Replies:** 10\
**Last updated:** [March 9, 2021, 11:05pm UTC](https://discourse.julialang.org/t/analog-of-markevery-in-plots-jl/10269 "2021-03-09T23:05:26Z")

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Matplotlib had a nice feature, markevery=n, that, for a bivariate data set, allowed you to only plot every n-th point. This was quite useful if you had an abundance of data and wanted to reduce the graphical intensity o…

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## [Question on ODE system with inhomogeneous coefficients, parameters, code design](https://discourse.julialang.org/t/question-on-ode-system-with-inhomogeneous-coefficients-parameters-code-design/56849)

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**Author:** [@Ininterrompue](https://discourse.julialang.org/u/Ininterrompue)\
**Replies:** 5\
**Last updated:** [March 10, 2021, 6:08am UTC](https://discourse.julialang.org/t/question-on-ode-system-with-inhomogeneous-coefficients-parameters-code-design/56849 "2021-03-10T06:08:38Z")

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Hi, I have a question relating to code design. I’m using some ODE solvers to calculate a system of ODEs with time-varying coefficients which I am interested in. They take on the form F, G, and dG in the MWE and depend o…

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