# General Usage

**URL:** https://discourse.julialang.org/c/usage/6.md?page=748

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

**Page:** 749

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## [Property Inheritance Pattern](https://discourse.julialang.org/t/property-inheritance-pattern/40101)

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**Author:** [@virtualgraham](https://discourse.julialang.org/u/virtualgraham)\
**Replies:** 20\
**Last updated:** [May 26, 2020, 3:09am UTC](https://discourse.julialang.org/t/property-inheritance-pattern/40101 "2020-05-26T03:09:36Z")

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As of version 1.4 Julia does not support property inheritance. However, many other languages such as Python do support inheritance and porting libraries from these languages becomes difficult. I am proposing an informal…

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## [Why isn't 10^6 evaluated at compile time?](https://discourse.julialang.org/t/why-isnt-10-6-evaluated-at-compile-time/40124)

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**Author:** [@robsmith11](https://discourse.julialang.org/u/robsmith11)\
**Replies:** 21\
**Last updated:** [May 25, 2020, 11:12pm UTC](https://discourse.julialang.org/t/why-isnt-10-6-evaluated-at-compile-time/40124 "2020-05-25T23:12:29Z")

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I was optimizing some code in the hot path and was surprised to see that constants written as 10^6 were being evaluated at run-time. Isn’t evaluating constants like this one of the simplest optimizations? Why wouldn’t …

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## [Very slow execution time](https://discourse.julialang.org/t/very-slow-execution-time/40141)

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**Author:** [@Adamszk](https://discourse.julialang.org/u/Adamszk)\
**Replies:** 4\
**Last updated:** [May 25, 2020, 7:50pm UTC](https://discourse.julialang.org/t/very-slow-execution-time/40141 "2020-05-25T19:50:45Z")

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Hi, I just build Julia 1.4.2. (I could not install prebuild). I managed to run Julia Kernel in jupyter. To test OrdinaryDIffEq tutorial, I run introductory page. I noticed that Julia takes like 2-4 seconds to print …

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## [Made Julia quit and now won't run even after re-install](https://discourse.julialang.org/t/made-julia-quit-and-now-wont-run-even-after-re-install/39805)

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**Author:** [@HelgavonLichtenstein](https://discourse.julialang.org/u/HelgavonLichtenstein)\
**Replies:** 11\
**Last updated:** [May 25, 2020, 3:36pm UTC](https://discourse.julialang.org/t/made-julia-quit-and-now-wont-run-even-after-re-install/39805 "2020-05-25T15:36:38Z")

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I pasted the error message here I was using callbacks with differential equations and comprehension. Julia quit and when I tried to run Atom again there was an error regarding resolve (?). I de-installed and re-instal…

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## [Warning in package dependency that I do not understand](https://discourse.julialang.org/t/warning-in-package-dependency-that-i-do-not-understand/40110)

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**Author:** [@sylvaticus](https://discourse.julialang.org/u/sylvaticus)\
**Replies:** 6\
**Last updated:** [May 25, 2020, 3:15pm UTC](https://discourse.julialang.org/t/warning-in-package-dependency-that-i-do-not-understand/40110 "2020-05-25T15:15:26Z")

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I am developing a package (Bblt) and at a certain point I added (or at least, I thought to have added) a dependency to ProgressMeter. I did that by activating the package environment and adding ProgressMeter. This acti…

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## [Julia has exited. Press Enter to start a new session.!](https://discourse.julialang.org/t/julia-has-exited-press-enter-to-start-a-new-session/40122)

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**Author:** [@SackMyRedBullz](https://discourse.julialang.org/u/SackMyRedBullz)\
**Replies:** 1\
**Last updated:** [May 25, 2020, 2:24pm UTC](https://discourse.julialang.org/t/julia-has-exited-press-enter-to-start-a-new-session/40122 "2020-05-25T14:24:12Z")

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My Julia was working just fine this morning, but after opening and closing it, suddenly I could not use the software and no matter what i did it just states: Julia has exited. Press Enter to start a new session. with …

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## [How to list the sysimage that is used](https://discourse.julialang.org/t/how-to-list-the-sysimage-that-is-used/40127)

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**Author:** [@feanor12](https://discourse.julialang.org/u/feanor12)\
**Replies:** 0\
**Last updated:** [May 25, 2020, 2:13pm UTC](https://discourse.julialang.org/t/how-to-list-the-sysimage-that-is-used/40127 "2020-05-25T14:13:22Z")

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Is there a way to list the filename of the sysimage that is used? I checked versioninfo() but I could not find it.

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## [Being in julia and killing julia in package manager (\]) stops not all subprocesses resulting in problems later](https://discourse.julialang.org/t/being-in-julia-and-killing-julia-in-package-manager-stops-not-all-subprocesses-resulting-in-problems-later/39175)

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**Author:** [@DKad](https://discourse.julialang.org/u/DKad)\
**Replies:** 29\
**Last updated:** [May 25, 2020, 12:16pm UTC](https://discourse.julialang.org/t/being-in-julia-and-killing-julia-in-package-manager-stops-not-all-subprocesses-resulting-in-problems-later/39175 "2020-05-25T12:16:39Z")

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I have started julia REPL (v.1.4.1), went into the packet manager, ran update and finally stopped julia inside the packet manager with Ctrl-D. Unfortunately not all processes were stopped. I still had a process running: …

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## [Interact package not working](https://discourse.julialang.org/t/interact-package-not-working/40106)

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**Author:** [@Longblackcoffee](https://discourse.julialang.org/u/Longblackcoffee)\
**Replies:** 1\
**Last updated:** [May 25, 2020, 5:47am UTC](https://discourse.julialang.org/t/interact-package-not-working/40106 "2020-05-25T05:47:57Z")

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Ever since the latest Atom update, has anyone else been having trouble with the Interact package? Even when I tried running something super basic that worked before, like the following: using Plots using Interact gr() …

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## [Controlling info-level logging?](https://discourse.julialang.org/t/controlling-info-level-logging/34420)

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**Author:** [@oschulz](https://discourse.julialang.org/u/oschulz)\
**Replies:** 3\
**Last updated:** [May 25, 2020, 3:18am UTC](https://discourse.julialang.org/t/controlling-info-level-logging/34420 "2020-05-25T03:18:15Z")

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Is it possible to control @info logging, per module, like @debug. I need to disable info output for a module/package sometimes.

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## [Very poor performance with DistributedArrays?](https://discourse.julialang.org/t/very-poor-performance-with-distributedarrays/40085)

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**Author:** [@angelv](https://discourse.julialang.org/u/angelv)\
**Replies:** 6\
**Last updated:** [May 25, 2020, 12:58am UTC](https://discourse.julialang.org/t/very-poor-performance-with-distributedarrays/40085 "2020-05-25T00:58:27Z")

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Hello, I’m following the Parallel Computing course at JuliaAcademy, and I’m trying to replicate the results in the course when using DistributedArrays. In there a simple sum over 1e7 random numbers, when done without Di…

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## [Ignoring \`NaN\` with \`findmax()\`](https://discourse.julialang.org/t/ignoring-nan-with-findmax/39891)

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**Author:** [@sergevic](https://discourse.julialang.org/u/sergevic)\
**Replies:** 9\
**Last updated:** [May 25, 2020, 12:22am UTC](https://discourse.julialang.org/t/ignoring-nan-with-findmax/39891 "2020-05-25T00:22:53Z")

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Suppose I have the following array: a=\[NaN, 1,2,3\] If I use findmax(a), I obtain (NaN, 1). How can I use findmax() ignoring all NaN values? I tried findmax(filter(!isnan, a)) but it returns (3.0,3) when I want (3.0,4).…

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## [The best linear solver for sparse bandedblockbandedmatricies](https://discourse.julialang.org/t/the-best-linear-solver-for-sparse-bandedblockbandedmatricies/40052)

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**Author:** [@RangeFu](https://discourse.julialang.org/u/RangeFu)\
**Replies:** 30\
**Last updated:** [May 24, 2020, 9:36pm UTC](https://discourse.julialang.org/t/the-best-linear-solver-for-sparse-bandedblockbandedmatricies/40052 "2020-05-24T21:36:07Z")

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Hi Community, I’m working on a program that requires solving A\\B repeatedly, where A is a sparse matrix that looks like this (it’s from finite-difference of an 2d PDE). I was wondering is there any method that can u…

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## [Changing number format when concatenating](https://discourse.julialang.org/t/changing-number-format-when-concatenating/40084)

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**Author:** [@sergevic](https://discourse.julialang.org/u/sergevic)\
**Replies:** 6\
**Last updated:** [May 24, 2020, 8:59pm UTC](https://discourse.julialang.org/t/changing-number-format-when-concatenating/40084 "2020-05-24T20:59:59Z")

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I have an integer Array a=\[1,2,3,4\] and a floating Array b=\[0.5, 0.671, 0.875, 1.5\]. When I try to concatenate with cat(dims=2,a,b), I obtain what I want, but the integer numbers are now floating numbers: 4×2 Array{Flo…

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## [Is there a function to name generated plot or rename variable?](https://discourse.julialang.org/t/is-there-a-function-to-name-generated-plot-or-rename-variable/40064)

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**Author:** [@1634](https://discourse.julialang.org/u/1634)\
**Replies:** 3\
**Last updated:** [May 24, 2020, 12:03pm UTC](https://discourse.julialang.org/t/is-there-a-function-to-name-generated-plot-or-rename-variable/40064 "2020-05-24T12:03:23Z")

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Hi, I’d like to naming plot or variables in a for loop, interpolating corresponding id to their name, so later on I can use them in manner of my combination and order. I checked related functions by ?name but haven’t f…

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## [Printing of an Expr seems wrong](https://discourse.julialang.org/t/printing-of-an-expr-seems-wrong/40051)

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**Author:** [@Stephan\_Meyn](https://discourse.julialang.org/u/Stephan_Meyn)\
**Replies:** 2\
**Last updated:** [May 24, 2020, 5:18am UTC](https://discourse.julialang.org/t/printing-of-an-expr-seems-wrong/40051 "2020-05-24T05:18:16Z")

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I have an EXPR. dump() shows up as follows: dump(x) Expr head: Symbol :: args: Array{Any}((2,)) 1: Symbol afield 2: Symbol Union{Nothing, Int32} put print shows up as: print(x) afield::var"Union{Nothing, Int…

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## [Using the @memoize macro](https://discourse.julialang.org/t/using-the-memoize-macro/39992)

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**Author:** [@Nimpa](https://discourse.julialang.org/u/Nimpa)\
**Replies:** 1\
**Last updated:** [May 24, 2020, 12:07am UTC](https://discourse.julialang.org/t/using-the-memoize-macro/39992 "2020-05-24T00:07:40Z")

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macro memoize(fun::Expr) local call = fun.args\[1\] local name = call.args\[1\].args\[1\] local arg1 = call.args\[1\].args\[2\] local arg1\_name = arg1.args\[1\] local arg1\_type = arg1.args\[2\] local return\_type = call.args\[2\] local b…

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## [Why FOR Loop last iteration ITEM not available GLOBALLY?](https://discourse.julialang.org/t/why-for-loop-last-iteration-item-not-available-globally/40046)

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**Author:** [@santokalayil](https://discourse.julialang.org/u/santokalayil)\
**Replies:** 11\
**Last updated:** [May 23, 2020, 10:44pm UTC](https://discourse.julialang.org/t/why-for-loop-last-iteration-item-not-available-globally/40046 "2020-05-23T22:44:26Z")

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Can Someone help me: I am from a python background. for loop last interation item variable is globally available in Python. But Julia throws error. Why is it so?. Is there any other way to make that last iteration item…

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## [Compile-time recognition of parametric types e.g. K{T} for any K](https://discourse.julialang.org/t/compile-time-recognition-of-parametric-types-e-g-k-t-for-any-k/40041)

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**Author:** [@dataSurfer](https://discourse.julialang.org/u/dataSurfer)\
**Replies:** 3\
**Last updated:** [May 23, 2020, 9:20pm UTC](https://discourse.julialang.org/t/compile-time-recognition-of-parametric-types-e-g-k-t-for-any-k/40041 "2020-05-23T21:20:11Z")

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Hi, I’m don’t know how to get the compiler to recognise a type K{T} where K could be any type. For example: abstract type AbstractGeneric{T} end #... after defining further types \<: AbstractGeneric{T} for example ... #…

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## [Pass local module to a function?](https://discourse.julialang.org/t/pass-local-module-to-a-function/40021)

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**Author:** [@pixel27](https://discourse.julialang.org/u/pixel27)\
**Replies:** 1\
**Last updated:** [May 23, 2020, 2:01pm UTC](https://discourse.julialang.org/t/pass-local-module-to-a-function/40021 "2020-05-23T14:01:47Z")

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I’m trying to create a minimal working example of a Documenter error I’m experiencing. However I’m having trouble passing the “local” module to the doctest function, This is what I’m trying: using Documenter module Fo…

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## [Implement Hessenberg factorization](https://discourse.julialang.org/t/implement-hessenberg-factorization/40006)

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**Author:** [@A.U.M](https://discourse.julialang.org/u/A.U.M)\
**Replies:** 4\
**Last updated:** [May 23, 2020, 1:44pm UTC](https://discourse.julialang.org/t/implement-hessenberg-factorization/40006 "2020-05-23T13:44:59Z")

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I am trying to Implement Hessenberg factorization in the following code. function GivensRotation(a::Float64, b::Float64) # Calculate the Given's rotation that rotates \[a;b\] to \[r;0\]: c = 0.; s = 0.; r = 0. if ( b ==…

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## [SQLite and locking](https://discourse.julialang.org/t/sqlite-and-locking/40018)

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**Author:** [@mlhetland](https://discourse.julialang.org/u/mlhetland)\
**Replies:** 0\
**Last updated:** [May 23, 2020, 1:01pm UTC](https://discourse.julialang.org/t/sqlite-and-locking/40018 "2020-05-23T13:01:10Z")

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I had a couple of processes working (intermittently) on the same SQLite file, and got a lock exception – and I couldn’t find any obvious way of handling that, other than using the low-level API or a loop with try/catch. …

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## [Remote Julia Process in Juno](https://discourse.julialang.org/t/remote-julia-process-in-juno/23230)

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**Author:** [@clinton](https://discourse.julialang.org/u/clinton)\
**Replies:** 11\
**Last updated:** [May 23, 2020, 9:49am UTC](https://discourse.julialang.org/t/remote-julia-process-in-juno/23230 "2020-05-23T09:49:41Z")

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I am trying to set up a remote Julia process in Juno, so I can use a powerful research server instead of a cruddy laptop. First, I tried to follow the FAQ for Juno. I opened a terminal, SSHed into the server, launched J…

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## [Trying to install CauseMap, error...HELP](https://discourse.julialang.org/t/trying-to-install-causemap-error-help/39736)

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**Author:** [@rklee1](https://discourse.julialang.org/u/rklee1)\
**Replies:** 6\
**Last updated:** [May 23, 2020, 5:55am UTC](https://discourse.julialang.org/t/trying-to-install-causemap-error-help/39736 "2020-05-23T05:55:02Z")

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Whenever I try to install CauseMap, I get this message: julia\> using Pkg julia\> Pkg.add(“CauseMap”) Updating registry at ~/.julia/registries/General Updating git-repo https://github.com/JuliaRegistries/General.git E…

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## [Large matrix with many updates](https://discourse.julialang.org/t/large-matrix-with-many-updates/39972)

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**Author:** [@alperyilmaz](https://discourse.julialang.org/u/alperyilmaz)\
**Replies:** 7\
**Last updated:** [May 23, 2020, 12:11am UTC](https://discourse.julialang.org/t/large-matrix-with-many-updates/39972 "2020-05-23T00:11:20Z")

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Hi, I would like to calculate a count matrix (expected to be 65,000x65,000) and then calculate PMI and then calculate SVD on it. Unfortunately many “large matrix” samples, tutorials start with rand(n,n) where the matri…

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## [Build fails with ERROR: Unsatisfiable requirements detected for package FFTW](https://discourse.julialang.org/t/build-fails-with-error-unsatisfiable-requirements-detected-for-package-fftw/39996)

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**Author:** [@ctkelley](https://discourse.julialang.org/u/ctkelley)\
**Replies:** 0\
**Last updated:** [May 22, 2020, 9:17pm UTC](https://discourse.julialang.org/t/build-fails-with-error-unsatisfiable-requirements-detected-for-package-fftw/39996 "2020-05-22T21:17:31Z")

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I know that question has come up before. I’m not sure I fully understand the solutions, however. I just added FFTW and AbstractFFTs as dependencies to a package. I’m getting this (see Travis CI - Test and Deploy with C…

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## [Debugger.jl: Access object \`%2\`](https://discourse.julialang.org/t/debugger-jl-access-object-2/39959)

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**Author:** [@gdkrmr](https://discourse.julialang.org/u/gdkrmr)\
**Replies:** 7\
**Last updated:** [May 22, 2020, 8:48pm UTC](https://discourse.julialang.org/t/debugger-jl-access-object-2/39959 "2020-05-22T20:48:30Z")

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I am trying to debug some code using Debug.jl: In \_pullback(ctx, f, args) at /home/gkraemer/.julia/packages/Zygote/YeCEW/src/compiler/interface2.jl:7 1 1 ─ $(Expr(:meta, :inline)) 2 │ %2 = (ZygoteRules.\_p…

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## [Issue plotting from REPL](https://discourse.julialang.org/t/issue-plotting-from-repl/39784)

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**Author:** [@Gaston](https://discourse.julialang.org/u/Gaston)\
**Replies:** 7\
**Last updated:** [May 22, 2020, 8:35pm UTC](https://discourse.julialang.org/t/issue-plotting-from-repl/39784 "2020-05-22T20:35:58Z")

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Hi, I’m facing a problem trying to plot from the REPL (that was working fine but for some reason has decided to stop doing so). If I run this simple code: julia\> using Plots julia\> gr() julia\> x = Vector(1:pi/10:6\*p…

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## [Getproperty optimization in struct](https://discourse.julialang.org/t/getproperty-optimization-in-struct/39990)

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**Author:** [@kirtsar](https://discourse.julialang.org/u/kirtsar)\
**Replies:** 1\
**Last updated:** [May 22, 2020, 8:29pm UTC](https://discourse.julialang.org/t/getproperty-optimization-in-struct/39990 "2020-05-22T20:29:00Z")

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I have the following code (example): struct Foo{N} t :: NTuple{N, Int} end foo = Foo((1,2,3)) Now if I try to get access to t field, I have some unnecessary allocations: using BenchmarkTools @benchmark getpropert…

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## [Help with LU factorization](https://discourse.julialang.org/t/help-with-lu-factorization/39911)

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**Author:** [@A.U.M](https://discourse.julialang.org/u/A.U.M)\
**Replies:** 21\
**Last updated:** [May 22, 2020, 2:14pm UTC](https://discourse.julialang.org/t/help-with-lu-factorization/39911 "2020-05-22T14:14:04Z")

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Is that possible to Implement 𝐿𝑈 factorization without row pivoting ? can someone give me an example?

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