# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1719

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

**Page:** 1720

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## [Introductory textbooks](https://discourse.julialang.org/t/introductory-textbooks/41214)

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**Author:** [@Ramayya](https://discourse.julialang.org/u/Ramayya)\
**Replies:** 5\
**Last updated:** [June 12, 2020, 7:56pm UTC](https://discourse.julialang.org/t/introductory-textbooks/41214 "2020-06-12T19:56:02Z")

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Dr. Shah, Need a very good introductory publication on “Julia" with illustrations, similar to the book “Illustrating C (revised edition ansi iso version)” by Donald Alcock (1992) or “Illustrating Pascal” by Donald Alcoc…

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## [Using a specific commit or branch when \`using mypkg\`](https://discourse.julialang.org/t/using-a-specific-commit-or-branch-when-using-mypkg/41293)

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**Author:** [@affans](https://discourse.julialang.org/u/affans)\
**Replies:** 3\
**Last updated:** [June 12, 2020, 7:02pm UTC](https://discourse.julialang.org/t/using-a-specific-commit-or-branch-when-using-mypkg/41293 "2020-06-12T19:02:01Z")

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I have a simulation model that is in the form of a Julia package, i.e. I can do using mypkg and call the function run(). This works fine, but I have several scientific projects that use this model and each project is sli…

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## [Large CPU time overhead RK4 ODE solver for parabolic problem](https://discourse.julialang.org/t/large-cpu-time-overhead-rk4-ode-solver-for-parabolic-problem/41174)

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**Author:** [@egcjm](https://discourse.julialang.org/u/egcjm)\
**Replies:** 15\
**Last updated:** [June 12, 2020, 7:00pm UTC](https://discourse.julialang.org/t/large-cpu-time-overhead-rk4-ode-solver-for-parabolic-problem/41174 "2020-06-12T19:00:34Z")

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I am solving a simple periodic vector parabolic equation using DifferentialEquations’ RK4() ODE solver. The code below is self contained. For the parameters specified, the ODE solver on my computer takes 0.23s (average …

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## [How can I tell if a compilation is happening?](https://discourse.julialang.org/t/how-can-i-tell-if-a-compilation-is-happening/41292)

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**Author:** [@miak](https://discourse.julialang.org/u/miak)\
**Replies:** 2\
**Last updated:** [June 12, 2020, 6:57pm UTC](https://discourse.julialang.org/t/how-can-i-tell-if-a-compilation-is-happening/41292 "2020-06-12T18:57:24Z")

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If I have a type struct Foo{N} end and N is intended to be a value, do methods on Foo{N} where N get compiled for each value of N or each type? For example, if I have a function foo\_stuff(f::Foo{N}) where {N} and I call …

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## [Lyapunov spectrum](https://discourse.julialang.org/t/lyapunov-spectrum/41281)

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**Author:** [@AhmedAlreweny](https://discourse.julialang.org/u/AhmedAlreweny)\
**Replies:** 0\
**Last updated:** [June 12, 2020, 4:45pm UTC](https://discourse.julialang.org/t/lyapunov-spectrum/41281 "2020-06-12T16:45:16Z")

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I have a bit of confusion using the function lyapunovs(ds::DynamicalSystem, N \[, k::Int | Q0\]; kwargs...) -\> λs in ChaosTools.lyapunovs. I am not sure if the second argument N can be seen as the number of time steps, o…

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## [Function callback with GtkSwitch](https://discourse.julialang.org/t/function-callback-with-gtkswitch/41287)

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**Author:** [@Christopher\_Fisher](https://discourse.julialang.org/u/Christopher_Fisher)\
**Replies:** 0\
**Last updated:** [June 12, 2020, 5:29pm UTC](https://discourse.julialang.org/t/function-callback-with-gtkswitch/41287 "2020-06-12T17:29:18Z")

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Hi all- I’m trying to create a function callback for GtkSwitch. What I current have does not work: using Gtk win = GtkWindow() switch = Gtk.GtkSwitchLeaf() f(x) = println("Swiched!") signal\_connect(f, switch, :activate…

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## [Give data by cmd?](https://discourse.julialang.org/t/give-data-by-cmd/41254)

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**Author:** [@Ravinder\_Ram](https://discourse.julialang.org/u/Ravinder_Ram)\
**Replies:** 7\
**Last updated:** [June 12, 2020, 5:20pm UTC](https://discourse.julialang.org/t/give-data-by-cmd/41254 "2020-06-12T17:20:49Z")

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let’s suppose i make function sum(x,y) { x + y}. I want to input(data) by cmd. how to do that?

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## [Match exact \`axes\`, something more strict than broadcasting or \`map!\`](https://discourse.julialang.org/t/match-exact-axes-something-more-strict-than-broadcasting-or-map/41206)

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**Author:** [@goretkin](https://discourse.julialang.org/u/goretkin)\
**Replies:** 2\
**Last updated:** [June 12, 2020, 5:08pm UTC](https://discourse.julialang.org/t/match-exact-axes-something-more-strict-than-broadcasting-or-map/41206 "2020-06-12T17:08:17Z")

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Is there an operation that is strict in the sense that the destination has to exactly equal the axes of the source? using OffsetArrays s = 1 a5\_10 = fill(0, 10:15) a5\_0 = fill(1, 0:5) a4\_0 = fill(2, 0:4) a5\_10 .= s # a…

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## [Multi Way Summary](https://discourse.julialang.org/t/multi-way-summary/41269)

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**Author:** [@bernhard](https://discourse.julialang.org/u/bernhard)\
**Replies:** 3\
**Last updated:** [June 12, 2020, 4:08pm UTC](https://discourse.julialang.org/t/multi-way-summary/41269 "2020-06-12T16:08:15Z")

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All I am looking for a simple way to perform a summary on multiple levels Attached is a screenshot from SAS, which shows what I am trying to achieve (consider the first row as well as the subsequent 26 rows). Is there …

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## [Should Revise work within the debugger?](https://discourse.julialang.org/t/should-revise-work-within-the-debugger/41240)

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**Author:** [@Alon](https://discourse.julialang.org/u/Alon)\
**Replies:** 6\
**Last updated:** [June 12, 2020, 3:49pm UTC](https://discourse.julialang.org/t/should-revise-work-within-the-debugger/41240 "2020-06-12T15:49:05Z")

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(Disclaimer: I’m a newbie) I wanted to learn how Revise work. I created a function within a module: in a file called some\_module.jl: module myModule function myFunc(name) println("Hello ",name) end end In a diffe…

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## [Newbie question about loop fusion and broadcasting](https://discourse.julialang.org/t/newbie-question-about-loop-fusion-and-broadcasting/41210)

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**Author:** [@cwindolf](https://discourse.julialang.org/u/cwindolf)\
**Replies:** 9\
**Last updated:** [June 12, 2020, 3:47pm UTC](https://discourse.julialang.org/t/newbie-question-about-loop-fusion-and-broadcasting/41210 "2020-06-12T15:47:16Z")

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Dear JuliaLang, I’m excited to get started with Julia as a long-time Python user, tired of typing np.array. One thing that is really exciting to me is the ability to avoid writing my own ufuncs, especially avoiding the …

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## [Why there are different execution times for same function calls](https://discourse.julialang.org/t/why-there-are-different-execution-times-for-same-function-calls/41259)

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**Author:** [@akhil\_teja](https://discourse.julialang.org/u/akhil_teja)\
**Replies:** 4\
**Last updated:** [June 12, 2020, 3:37pm UTC](https://discourse.julialang.org/t/why-there-are-different-execution-times-for-same-function-calls/41259 "2020-06-12T15:37:54Z")

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Below is my Code: function bisection(custom\_func,starting::T,ending::K) where {T\<:Real,K\<:Real} if custom\_func(starting)==0 return starting elseif custom\_func(ending)==0 return ending elseif …

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## [Reduce: init for non-empty collections](https://discourse.julialang.org/t/reduce-init-for-non-empty-collections/41181)

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**Author:** [@aplavin](https://discourse.julialang.org/u/aplavin)\
**Replies:** 8\
**Last updated:** [June 12, 2020, 2:58pm UTC](https://discourse.julialang.org/t/reduce-init-for-non-empty-collections/41181 "2020-06-12T14:58:16Z")

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I noticed that the docs for reduce say: reduce(op, itr; \[init\]) ... If provided, the initial value init must be a neutral element for op that will be returned for empty collections. It is unspecified whether init…

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## [Setting an upper and lower limit on a differential equation](https://discourse.julialang.org/t/setting-an-upper-and-lower-limit-on-a-differential-equation/41144)

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**Author:** [@HelgavonLichtenstein](https://discourse.julialang.org/u/HelgavonLichtenstein)\
**Replies:** 14\
**Last updated:** [June 12, 2020, 2:56pm UTC](https://discourse.julialang.org/t/setting-an-upper-and-lower-limit-on-a-differential-equation/41144 "2020-06-12T14:56:51Z")

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This is the last piece I need for my model to work, yet the result keeps going over what I thought I had set the limit to. The simplified scenario is: there is a fishing boat - on the boat work is done - the amount of w…

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## [Implementing recipes on a per package basis?](https://discourse.julialang.org/t/implementing-recipes-on-a-per-package-basis/41198)

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**Author:** [@juliohm](https://discourse.julialang.org/u/juliohm)\
**Replies:** 8\
**Last updated:** [June 12, 2020, 1:24pm UTC](https://discourse.julialang.org/t/implementing-recipes-on-a-per-package-basis/41198 "2020-06-12T13:24:38Z")

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I recently started thinking about an alternative strategy to improving the end user experience in the plotting ecosystem. Is it correct that the recipe system nowadays is decoupled from Plots.jl? For instance, could an a…

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## [Can we have \`String\`s/\`Cmd\`s as type parameter?](https://discourse.julialang.org/t/can-we-have-string-s-cmd-s-as-type-parameter/31647)

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**Author:** [@singularitti](https://discourse.julialang.org/u/singularitti)\
**Replies:** 2\
**Last updated:** [June 12, 2020, 12:06pm UTC](https://discourse.julialang.org/t/can-we-have-string-s-cmd-s-as-type-parameter/31647 "2020-06-12T12:06:33Z")

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I am working on Julia 1.3 and find we can have Numbers, Symbols and Chars, etc., as type parameters, but they cannot be Strings, Cmds, etc. julia\> struct A{T} end julia\> A{333}() A{333}() julia\> A{"fd"}() ERROR…

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## [BenchmarkTools keep failing in a loop](https://discourse.julialang.org/t/benchmarktools-keep-failing-in-a-loop/41261)

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**Author:** [@tirthasheshpatel](https://discourse.julialang.org/u/tirthasheshpatel)\
**Replies:** 4\
**Last updated:** [June 12, 2020, 11:59am UTC](https://discourse.julialang.org/t/benchmarktools-keep-failing-in-a-loop/41261 "2020-06-12T11:59:05Z")

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I am trying to use BenchmarkTools to benchmark some of my algorithms but I keep getting an error I don’t really understand. Why does it keep failing in a loop? I think the @benchmark macro isn’t a blocking line due to wh…

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## [Packages to determine confidence intervals](https://discourse.julialang.org/t/packages-to-determine-confidence-intervals/41233)

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**Author:** [@feanor12](https://discourse.julialang.org/u/feanor12)\
**Replies:** 1\
**Last updated:** [June 12, 2020, 11:16am UTC](https://discourse.julialang.org/t/packages-to-determine-confidence-intervals/41233 "2020-06-12T11:16:34Z")

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As LsqFit.jl only calculates the standard error by using the Jacobian at the best-fit position I thought I try to write a small package for determining the confidence interval by data exploration. https://github.com/fea…

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## [Cant install OpenSpecFun\_jll](https://discourse.julialang.org/t/cant-install-openspecfun-jll/33593)

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**Author:** [@mariok90](https://discourse.julialang.org/u/mariok90)\
**Replies:** 50\
**Last updated:** [June 12, 2020, 9:45am UTC](https://discourse.julialang.org/t/cant-install-openspecfun-jll/33593 "2020-06-12T09:45:35Z")

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When I install JuMP I get the following error. Any idea on how to fix this? Installed OpenSpecFun\_jll ──── v0.5.3+1 ERROR: Unable to automatically install 'OpenSpecFun' from '/homes2/ivw/kendzior/.julia/packages/OpenSpe…

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## [Off diagonal elements of Matrix](https://discourse.julialang.org/t/off-diagonal-elements-of-matrix/41169)

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**Author:** [@jamblejoe](https://discourse.julialang.org/u/jamblejoe)\
**Replies:** 14\
**Last updated:** [June 12, 2020, 9:37am UTC](https://discourse.julialang.org/t/off-diagonal-elements-of-matrix/41169 "2020-06-12T09:37:28Z")

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Hi, what is the Julia-way of obtaining off-diagonal elements of a matrix flattend as a vector, e.g. A = \[1 2; 3 4\] offdiag(A) = \[2, 3\] I stumbled across diagind but could not figure out how to do it neatly. Best, ja…

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## [How to insatll 'OpenBLAS' manually?](https://discourse.julialang.org/t/how-to-insatll-openblas-manually/41185)

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**Author:** [@jkwwwwow](https://discourse.julialang.org/u/jkwwwwow)\
**Replies:** 5\
**Last updated:** [June 12, 2020, 8:38am UTC](https://discourse.julialang.org/t/how-to-insatll-openblas-manually/41185 "2020-06-12T08:38:56Z")

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When I try to add POMDPSimulators I met the following error: julia\> import Pkg julia\> Pkg.add("POMDPSimulators") Updating registry at \`~/.julia/registries/General\` Updating git-repo \`https://github.com/JuliaRegis…

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## [Cannot \`convert\` an object of type Random.\_GLOBAL\_RNG to an object of type Random.MersenneTwister](https://discourse.julialang.org/t/cannot-convert-an-object-of-type-random-global-rng-to-an-object-of-type-random-mersennetwister/41172)

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**Author:** [@logankilpatrick](https://discourse.julialang.org/u/logankilpatrick)\
**Replies:** 2\
**Last updated:** [June 12, 2020, 8:20am UTC](https://discourse.julialang.org/t/cannot-convert-an-object-of-type-random-global-rng-to-an-object-of-type-random-mersennetwister/41172 "2020-06-12T08:20:06Z")

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Here is the error: ERROR: LoadError: MethodError: Cannot \`convert\` an object of type Random.\_GLOBAL\_RNG to an object of type Random.MersenneTwister Closest candidates are: convert(::Type{S}, ::T) where {S, T\<:Categori…

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## [Zygote in Turing: Mutating arrays is not supported](https://discourse.julialang.org/t/zygote-in-turing-mutating-arrays-is-not-supported/41155)

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**Author:** [@Manoj\_Gopalkrishnan](https://discourse.julialang.org/u/Manoj_Gopalkrishnan)\
**Replies:** 2\
**Last updated:** [June 12, 2020, 6:56am UTC](https://discourse.julialang.org/t/zygote-in-turing-mutating-arrays-is-not-supported/41155 "2020-06-12T06:56:19Z")

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I am trying to use Zygote in Turing. Here’s my MWE @model function mwe(B, ::Type{T} = Vector{Float64}) where {T} μ = mapslices(lsexp, B; dims=\[1\])\[1,:\] end mwe\_model = mwe(\[1.0 2; 3 4\]) mwe\_ch = sample(mwe\_model, N…

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## [Fresh Arch Linux install: UndefVarError: backend not defined](https://discourse.julialang.org/t/fresh-arch-linux-install-undefvarerror-backend-not-defined/41245)

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**Author:** [@fusion809](https://discourse.julialang.org/u/fusion809)\
**Replies:** 1\
**Last updated:** [June 12, 2020, 6:07am UTC](https://discourse.julialang.org/t/fresh-arch-linux-install-undefvarerror-backend-not-defined/41245 "2020-06-12T06:07:57Z")

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I just created a new Arch Linux install, and while on my old Arch Linux install my Julia scripts run fine, on this fresh install this one keeps returning the error: UndefVarError: backend not defined Stacktrace: \[1\] p…

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## [What Juno features do you use most?](https://discourse.julialang.org/t/what-juno-features-do-you-use-most/39271)

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**Author:** [@pfitzseb](https://discourse.julialang.org/u/pfitzseb)\
**Replies:** 108\
**Last updated:** [June 12, 2020, 3:50am UTC](https://discourse.julialang.org/t/what-juno-features-do-you-use-most/39271 "2020-06-12T03:50:34Z")

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Hey everyone, since we’re considering to move Juno from Atom to VSCode, we’d like to know what parts of Juno you use (and/or like) most. Is it inline evaluation (in a specified module), the remote execution capabilitie…

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## [Gadfly Geom.ribbon bounded left and right - Feature Request](https://discourse.julialang.org/t/gadfly-geom-ribbon-bounded-left-and-right-feature-request/39161)

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**Author:** [@Humphrey\_Lee](https://discourse.julialang.org/u/Humphrey_Lee)\
**Replies:** 2\
**Last updated:** [June 12, 2020, 1:12am UTC](https://discourse.julialang.org/t/gadfly-geom-ribbon-bounded-left-and-right-feature-request/39161 "2020-06-12T01:12:06Z")

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Current implementation of Geom.ribbon is to draw a ribbon at the positions in x bounded above and below by ymax and ymin. Is it possible to draw a ribbon at the positions in y bounded left and right by xmax and xmin? T…

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## [Anonymous function applied to multiple arguments](https://discourse.julialang.org/t/anonymous-function-applied-to-multiple-arguments/41221)

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**Author:** [@hendri54](https://discourse.julialang.org/u/hendri54)\
**Replies:** 13\
**Last updated:** [June 12, 2020, 1:10am UTC](https://discourse.julialang.org/t/anonymous-function-applied-to-multiple-arguments/41221 "2020-06-12T01:10:22Z")

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What is the correct syntax for the following: julia\> xV = 1:5; yV = 2:6; julia\> findall((x,y) -\> ((x \> 2) & (y \> 4)), (xV, yV)) The docs only have examples with one argument.

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## [Error while using @time on a Multi-threaded Julia function!](https://discourse.julialang.org/t/error-while-using-time-on-a-multi-threaded-julia-function/41189)

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**Author:** [@Saad\_Mahmud](https://discourse.julialang.org/u/Saad_Mahmud)\
**Replies:** 9\
**Last updated:** [June 12, 2020, 12:51am UTC](https://discourse.julialang.org/t/error-while-using-time-on-a-multi-threaded-julia-function/41189 "2020-06-12T00:51:05Z")

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I am trying to time a Julia function and inside that function, I am using Multiple threads. Example of the code is given below: function function1(input) @threads for i in 1:N #does something with the input end end for…

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## [Query.jl @mutate command does not preserve column types](https://discourse.julialang.org/t/query-jl-mutate-command-does-not-preserve-column-types/41231)

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**Author:** [@affans](https://discourse.julialang.org/u/affans)\
**Replies:** 4\
**Last updated:** [June 12, 2020, 12:46am UTC](https://discourse.julialang.org/t/query-jl-mutate-command-does-not-preserve-column-types/41231 "2020-06-12T00:46:02Z")

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I have a dataframe that I read from CSV. I.e. df = CSV.read("myfile.csv" , header=1, select=(i, name) -\> i \< 5 && return true) The parser automatically gets the correct type of each column 92×5 DataFrame │ Row │ neck …

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## [How to make an abstract type as a super type of composite types](https://discourse.julialang.org/t/how-to-make-an-abstract-type-as-a-super-type-of-composite-types/27174)

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**Author:** [@Volker](https://discourse.julialang.org/u/Volker)\
**Replies:** 8\
**Last updated:** [June 11, 2020, 11:49pm UTC](https://discourse.julialang.org/t/how-to-make-an-abstract-type-as-a-super-type-of-composite-types/27174 "2020-06-11T23:49:58Z")

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Hi, I would like to create an abstract type, which is a supertype of several composite types, which I coded in modules, so that a function just works for the composite types, which have this specific abstract type as su…

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