# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1718

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

**Page:** 1719

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## [Large Number Formats](https://discourse.julialang.org/t/large-number-formats/41357)

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**Author:** [@johnh](https://discourse.julialang.org/u/johnh)\
**Replies:** 1\
**Last updated:** [June 14, 2020, 7:21am UTC](https://discourse.julialang.org/t/large-number-formats/41357 "2020-06-14T07:21:19Z")

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## [Custom dataset](https://discourse.julialang.org/t/custom-dataset/41329)

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**Author:** [@SubhadityaMukherjee](https://discourse.julialang.org/u/SubhadityaMukherjee)\
**Replies:** 2\
**Last updated:** [June 14, 2020, 6:42am UTC](https://discourse.julialang.org/t/custom-dataset/41329 "2020-06-14T06:42:01Z")

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Hello! I am new here. I have been trying to use Metalhead.jl/Flux.jl to train custom image classifiers but I cant seem to be able to load data from a folder directly. (Not part of the standard datasets). Say I have a f…

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## [How to extend a vector the Julian way](https://discourse.julialang.org/t/how-to-extend-a-vector-the-julian-way/41351)

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**Author:** [@erlebach](https://discourse.julialang.org/u/erlebach)\
**Replies:** 1\
**Last updated:** [June 14, 2020, 3:06am UTC](https://discourse.julialang.org/t/how-to-extend-a-vector-the-julian-way/41351 "2020-06-14T03:06:04Z")

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In Python, given a list a=\[1,2\], I can extend it with a.extend(\[3,4\]) Now a contains \[1,2,3,4\]. Does Julia have a simple way to extend vectors? Of course, vcat comes to mind: a = \[1,2\] a = vcat(a,\[3,4\]) Are there be…

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## [Keep Gtk dialog windows on top](https://discourse.julialang.org/t/keep-gtk-dialog-windows-on-top/41350)

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**Author:** [@cvq](https://discourse.julialang.org/u/cvq)\
**Replies:** 0\
**Last updated:** [June 14, 2020, 2:13am UTC](https://discourse.julialang.org/t/keep-gtk-dialog-windows-on-top/41350 "2020-06-14T02:13:54Z")

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How to keep Gtk open\_dialog always on top of the others?’ Thank you.

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## [Slow arbitrary base exponentiation, a^b](https://discourse.julialang.org/t/slow-arbitrary-base-exponentiation-a-b/25386)

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**Author:** [@JesseSantoso](https://discourse.julialang.org/u/JesseSantoso)\
**Replies:** 22\
**Last updated:** [June 14, 2020, 1:49am UTC](https://discourse.julialang.org/t/slow-arbitrary-base-exponentiation-a-b/25386 "2020-06-14T01:49:25Z")

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Hey everyone, I’ve been having fun optimising my code and I’ve noticed that raising a Float64 to the power of another Float64 (e.g. a^b) is very slow compared to base e exponentiation using the exp() function, even to th…

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## [Making iterators as fast as loops](https://discourse.julialang.org/t/making-iterators-as-fast-as-loops/21377)

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**Author:** [@pablosanjose](https://discourse.julialang.org/u/pablosanjose)\
**Replies:** 25\
**Last updated:** [June 14, 2020, 12:34am UTC](https://discourse.julialang.org/t/making-iterators-as-fast-as-loops/21377 "2020-06-14T00:34:42Z")

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I’m trying to build an efficient iterator for a bunch of nested loops, so that the inner loops depend on the outer loops. I’m having problems achieving comparable performance with the iterator approach as with the loop a…

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## [A question about Atom](https://discourse.julialang.org/t/a-question-about-atom/36095)

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**Author:** [@abcde](https://discourse.julialang.org/u/abcde)\
**Replies:** 2\
**Last updated:** [June 13, 2020, 9:58pm UTC](https://discourse.julialang.org/t/a-question-about-atom/36095 "2020-06-13T21:58:09Z")

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All the required installation packages are installed but it does not work. :sleepy:

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## [Plots Heatmap is not showing categorical variable](https://discourse.julialang.org/t/plots-heatmap-is-not-showing-categorical-variable/41340)

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**Author:** [@affans](https://discourse.julialang.org/u/affans)\
**Replies:** 2\
**Last updated:** [June 13, 2020, 9:29pm UTC](https://discourse.julialang.org/t/plots-heatmap-is-not-showing-categorical-variable/41340 "2020-06-13T21:29:34Z")

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I am trying to plot a heatmap where the data is coming from a DataFrame. The arrays look like the following yvals = df\_normal\[:, :county\] xvals = names(df\_normal)\[dbegin:dend\] zvals = Matrix(df\_normal\[:, dbegin:dend\]) w…

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## [LangServer keeps indexing everytime I open up VS Code](https://discourse.julialang.org/t/langserver-keeps-indexing-everytime-i-open-up-vs-code/41275)

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**Author:** [@affans](https://discourse.julialang.org/u/affans)\
**Replies:** 4\
**Last updated:** [June 13, 2020, 9:00pm UTC](https://discourse.julialang.org/t/langserver-keeps-indexing-everytime-i-open-up-vs-code/41275 "2020-06-13T21:00:20Z")

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I am using the new WSL2 feature in Windows and have installed Ubuntu on my machine. The goal is to move my dev stuff over to WSL2. I uninstalled Julia from my Windows machine and deleted the .julia folder. I furthered u…

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## [Dance.jl - Python Flask equivalent web framework](https://discourse.julialang.org/t/dance-jl-python-flask-equivalent-web-framework/38560)

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**Author:** [@yoh-meyers](https://discourse.julialang.org/u/yoh-meyers)\
**Replies:** 3\
**Last updated:** [June 13, 2020, 8:46pm UTC](https://discourse.julialang.org/t/dance-jl-python-flask-equivalent-web-framework/38560 "2020-06-13T20:46:06Z")

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Hello Julia community, Am pleased to announce a new web framework focused on facilitating process of outputting Julia computed data to the web very easily. Feel that reason Python is still more mainstream than Julia is …

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## [Setfield: set properties of nested subfields](https://discourse.julialang.org/t/setfield-set-properties-of-nested-subfields/41304)

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**Author:** [@Ian\_Slagle](https://discourse.julialang.org/u/Ian_Slagle)\
**Replies:** 4\
**Last updated:** [June 13, 2020, 6:11pm UTC](https://discourse.julialang.org/t/setfield-set-properties-of-nested-subfields/41304 "2020-06-13T18:11:56Z")

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I’m trying to use the setproperties function of Setfield.jl to set multiple different fields at once for immutable structs, but I’m running into this issue. using Setfield struct A foo::Int bar::Int end struct…

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## [Make typeof(T::Type) = Type{T}?](https://discourse.julialang.org/t/make-typeof-t-type-type-t/41333)

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**Author:** [@schlichtanders](https://discourse.julialang.org/u/schlichtanders)\
**Replies:** 0\
**Last updated:** [June 13, 2020, 5:26pm UTC](https://discourse.julialang.org/t/make-typeof-t-type-type-t/41333 "2020-06-13T17:26:35Z")

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Hi Julia pros, if we use e.g. typeof((Vector, Int, 1)) we get Tuple{UnionAll, DataType, Int}, which I guess is due to typeof(Vector) = UnionAll and the like. Wouldn’t it be better for the compiler and hence performance…

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## [Cannot start Julia 1.4.2](https://discourse.julialang.org/t/cannot-start-julia-1-4-2/41267)

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**Author:** [@Yifan\_Liu](https://discourse.julialang.org/u/Yifan_Liu)\
**Replies:** 7\
**Last updated:** [June 13, 2020, 5:02pm UTC](https://discourse.julialang.org/t/cannot-start-julia-1-4-2/41267 "2020-06-13T17:02:58Z")

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After an update to Julia 1.4.2, my Fedora 32 desktop cannot start Julia anymore. The error message says: julia: error while loading shared libraries: libLLVM-8jl.so: cannot open shared object file: No such file or dire…

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## [Is there a \`\`mytypeof((Vector, Int))\`\` returning \`\`Tuple{Type{Vector}, Type{Int}}\`\`?](https://discourse.julialang.org/t/is-there-a-mytypeof-vector-int-returning-tuple-type-vector-type-int/41322)

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**Author:** [@schlichtanders](https://discourse.julialang.org/u/schlichtanders)\
**Replies:** 2\
**Last updated:** [June 13, 2020, 12:00pm UTC](https://discourse.julialang.org/t/is-there-a-mytypeof-vector-int-returning-tuple-type-vector-type-int/41322 "2020-06-13T12:00:36Z")

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I just was surprised that some code was not optimized accordingly and I realized it is because I used something like typeof((Vector, Int, 1)) which unfortunately forgets the type information and returns Tuple{UnionAll, D…

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## [Use of Base.@propagate\_inbounds in OffsetArrays.jl](https://discourse.julialang.org/t/use-of-base-propagate-inbounds-in-offsetarrays-jl/41313)

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**Author:** [@jishnub](https://discourse.julialang.org/u/jishnub)\
**Replies:** 2\
**Last updated:** [June 13, 2020, 10:50am UTC](https://discourse.julialang.org/t/use-of-base-propagate-inbounds-in-offsetarrays-jl/41313 "2020-06-13T10:50:46Z")

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I am trying to understand how Base.@propagate\_inbounds works by studying its use in OffsetArrays.jl. Currently setindex! is implemented as @propagate\_inbounds function Base.setindex!(A::OffsetArray{T,N}, val, I::Vararg{…

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## [On iterators](https://discourse.julialang.org/t/on-iterators/41315)

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**Author:** [@binarygcd](https://discourse.julialang.org/u/binarygcd)\
**Replies:** 2\
**Last updated:** [June 13, 2020, 9:19am UTC](https://discourse.julialang.org/t/on-iterators/41315 "2020-06-13T09:19:51Z")

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Is there a plan for a shorter alternative to ‘Iterators.filter’ and the like? The ‘Iterators’ word takes quite a number of columns, especially if used multiple times. Why is it not allowed to use ‘takewhile’, ‘dropwhile…

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## [\[ANN\] Ripserer - Efficient Persistent Homology Computation in Julia](https://discourse.julialang.org/t/ann-ripserer-efficient-persistent-homology-computation-in-julia/40639)

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**Author:** [@mtsch](https://discourse.julialang.org/u/mtsch)\
**Replies:** 12\
**Last updated:** [June 13, 2020, 9:55am UTC](https://discourse.julialang.org/t/ann-ripserer-efficient-persistent-homology-computation-in-julia/40639 "2020-06-13T09:55:28Z")

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Hi guys, I’m pleased to announce Ripserer.jl, a pure Julia library for computing persistent homology. It uses the same algorithm as Ripser, which is known to be one of the fastest pieces of software for this purpose. T…

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## [Cookbook package for tested one-liners and snippets](https://discourse.julialang.org/t/cookbook-package-for-tested-one-liners-and-snippets/41291)

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**Author:** [@jules](https://discourse.julialang.org/u/jules)\
**Replies:** 3\
**Last updated:** [June 13, 2020, 9:30am UTC](https://discourse.julialang.org/t/cookbook-package-for-tested-one-liners-and-snippets/41291 "2020-06-13T09:30:57Z")

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The recent discussion on package registration waiting periods and the merit of one-function packages got me thinking. I think stackoverflow shows that there is a demand for simple functions that solve problems that are q…

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## [How to only return values from the last time step in a saving callback?](https://discourse.julialang.org/t/how-to-only-return-values-from-the-last-time-step-in-a-saving-callback/41276)

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**Author:** [@HelgavonLichtenstein](https://discourse.julialang.org/u/HelgavonLichtenstein)\
**Replies:** 1\
**Last updated:** [June 13, 2020, 7:47am UTC](https://discourse.julialang.org/t/how-to-only-return-values-from-the-last-time-step-in-a-saving-callback/41276 "2020-06-13T07:47:05Z")

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I’ve tried these combinations and haven’t found the correct one yet. cb\_save = SavingCallback(saving\_func, saved\_values, saveat=sol.t\[end\]) cb\_save = SavingCallback(saving\_func, saved\_values, save\_start=false,save\_ever…

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## [Efficient closures](https://discourse.julialang.org/t/efficient-closures/41262)

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**Author:** [@tfr](https://discourse.julialang.org/u/tfr)\
**Replies:** 4\
**Last updated:** [June 13, 2020, 6:18am UTC](https://discourse.julialang.org/t/efficient-closures/41262 "2020-06-13T06:18:23Z")

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Hello. I have a function of many variables, hermite\_interpolation(t, t\_array, f\_array, df\_array), and I want to use this function as the argument of another function, that I shall call do\_something(pulse). However, the …

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## [A question about Plots](https://discourse.julialang.org/t/a-question-about-plots/41311)

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**Author:** [@abcde](https://discourse.julialang.org/u/abcde)\
**Replies:** 3\
**Last updated:** [June 13, 2020, 4:16am UTC](https://discourse.julialang.org/t/a-question-about-plots/41311 "2020-06-13T04:16:52Z")

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The program has run ,but the scatter diagram does not show ,why? Is it too much data in my code?

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## [Macro through variable assignment](https://discourse.julialang.org/t/macro-through-variable-assignment/41280)

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**Author:** [@Magalame](https://discourse.julialang.org/u/Magalame)\
**Replies:** 3\
**Last updated:** [June 13, 2020, 3:42am UTC](https://discourse.julialang.org/t/macro-through-variable-assignment/41280 "2020-06-13T03:42:40Z")

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I want to use two macros (@m1(x), @m2(y)), so that the behaviour of @m2(y) would defer depending on if y = @m1(x) or not. Is this achievable as such? Or do I need to wrap the output of @m1 in a “label” type that would t…

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## [Gamma function at a negative whole number: a cautionary tale](https://discourse.julialang.org/t/gamma-function-at-a-negative-whole-number-a-cautionary-tale/41307)

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**Author:** [@billmclean](https://discourse.julialang.org/u/billmclean)\
**Replies:** 2\
**Last updated:** [June 13, 2020, 3:09am UTC](https://discourse.julialang.org/t/gamma-function-at-a-negative-whole-number-a-cautionary-tale/41307 "2020-06-13T03:09:00Z")

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Consider the following results: julia\> using SpecialFunctions julia\> gamma(-1.999) 500.4623295054461 julia\> gamma(-2.0) ERROR: DomainError with -2.0: NaN result for non-NaN input. julia\> gamma(-2.001) -499.5395437293…

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## [Add object to existing BSON file?](https://discourse.julialang.org/t/add-object-to-existing-bson-file/41305)

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**Author:** [@e3c6](https://discourse.julialang.org/u/e3c6)\
**Replies:** 1\
**Last updated:** [June 13, 2020, 1:44am UTC](https://discourse.julialang.org/t/add-object-to-existing-bson-file/41305 "2020-06-13T01:44:25Z")

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Suppose I saved a BSON file with BSON.@save "path/to/file.bson" obj1 obj2 . Then later on I create a new obj3 and I want to also add to this file, as if I had executed BSON.@save "path/to/file.bson" obj1 obj2 obj3 …

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## [Strange round() results?](https://discourse.julialang.org/t/strange-round-results/22446)

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**Author:** [@tomtom](https://discourse.julialang.org/u/tomtom)\
**Replies:** 8\
**Last updated:** [June 13, 2020, 12:56am UTC](https://discourse.julialang.org/t/strange-round-results/22446 "2020-06-13T00:56:21Z")

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I found that the results of round() are hard to understand: julia\> round(Int, 0.5) 0 julia\> round(Int, 1.49999999) 1 julia\> round(Int, 1.5) 2 julia\> round(Int, 2.5) 2 julia\> round(Int, 3.5) 4 julia\> round(Int, 4.5) 4 ju…

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## [Reading a file with blank last line](https://discourse.julialang.org/t/reading-a-file-with-blank-last-line/41257)

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**Author:** [@binarygcd](https://discourse.julialang.org/u/binarygcd)\
**Replies:** 1\
**Last updated:** [June 12, 2020, 10:48pm UTC](https://discourse.julialang.org/t/reading-a-file-with-blank-last-line/41257 "2020-06-12T22:48:02Z")

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I made a code for a problem that gets its inputs from a file. The inputs are integers and the last line is blank. Below are the ones I’ve tried. for line in eachline() isempty(strip(line)) && break n = parse(Int…

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## [About inheritance and abstract types](https://discourse.julialang.org/t/about-inheritance-and-abstract-types/5801)

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**Author:** [@tobydriscoll](https://discourse.julialang.org/u/tobydriscoll)\
**Replies:** 46\
**Last updated:** [June 12, 2020, 8:47pm UTC](https://discourse.julialang.org/t/about-inheritance-and-abstract-types/5801 "2020-06-12T20:47:23Z")

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There’s something about Julia style that I’m just not getting. Let’s say I want a Curve type for a curve in the complex plane. It’s meant to be abstract, since I will have different subtypes of Curve (Line, Circle, etc).…

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## [Understanding environments and DrWatson](https://discourse.julialang.org/t/understanding-environments-and-drwatson/41294)

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**Author:** [@affans](https://discourse.julialang.org/u/affans)\
**Replies:** 5\
**Last updated:** [June 12, 2020, 8:20pm UTC](https://discourse.julialang.org/t/understanding-environments-and-drwatson/41294 "2020-06-12T20:20:46Z")

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Suppose I have a package that looks like this module MyPkg using Distributions, DataFrames function a() end end There is an associated environment with this that has Project.toml.Manifest.toml files that tell MyP…

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## [Why are my linear interpolations 10x faster in MATLAB?](https://discourse.julialang.org/t/why-are-my-linear-interpolations-10x-faster-in-matlab/41232)

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**Author:** [@elenev](https://discourse.julialang.org/u/elenev)\
**Replies:** 26\
**Last updated:** [June 12, 2020, 8:35pm UTC](https://discourse.julialang.org/t/why-are-my-linear-interpolations-10x-faster-in-matlab/41232 "2020-06-12T20:35:06Z")

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The consensus on this forum seems to be that Interpolations.jl is extremely fast, so I must not be using it in a smart way. Here’s an MWE of the Matlab code I’m trying to adapt to Julia. If some stuff looks weird (e.g. …

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## [Update Conda JupyterLab kernel with Julia 1.4.2](https://discourse.julialang.org/t/update-conda-jupyterlab-kernel-with-julia-1-4-2/41289)

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**Author:** [@bobmccrory](https://discourse.julialang.org/u/bobmccrory)\
**Replies:** 4\
**Last updated:** [June 12, 2020, 8:15pm UTC](https://discourse.julialang.org/t/update-conda-jupyterlab-kernel-with-julia-1-4-2/41289 "2020-06-12T20:15:50Z")

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I’ve been building Conda JupyterLab notebooks with a Julia 1.4.1 kernel. I’ve downloaded 1.4.2, but JupyterLab doesn’t see it. Does anyone know how to fix this? Thanks.

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