# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1717

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

**Page:** 1718

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## [Using replace with a function of the match](https://discourse.julialang.org/t/using-replace-with-a-function-of-the-match/41264)

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**Author:** [@tlienart](https://discourse.julialang.org/u/tlienart)\
**Replies:** 4\
**Last updated:** [June 15, 2020, 8:58am UTC](https://discourse.julialang.org/t/using-replace-with-a-function-of-the-match/41264 "2020-06-15T08:58:54Z")

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Hello, It’s easy to recuperate the matched substring in replace and do something like: julia\> replace("foobar", r"b(\[a-z\])r" =\> s"\\1") "fooa" However I can’t pass the output to a function so for instance this: julia\> …

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## [Comparison of Windows 10 and Linux Julia](https://discourse.julialang.org/t/comparison-of-windows-10-and-linux-julia/41227)

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**Author:** [@PetrKryslUCSD](https://discourse.julialang.org/u/PetrKryslUCSD)\
**Replies:** 15\
**Last updated:** [June 15, 2020, 8:37am UTC](https://discourse.julialang.org/t/comparison-of-windows-10-and-linux-julia/41227 "2020-06-15T08:37:11Z")

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I was curious about some recent observations I made concerning the speed of sparse-matrix solve. Here are some measurements comparing Windows 10, WSL2, and Ubuntu 20.4, all running on the same laptop(HP Spectre 360 i7 a…

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## [Creating an anonymous function taking as arguments the elements in a vector](https://discourse.julialang.org/t/creating-an-anonymous-function-taking-as-arguments-the-elements-in-a-vector/41373)

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**Author:** [@Karel\_Van\_Brantegem](https://discourse.julialang.org/u/Karel_Van_Brantegem)\
**Replies:** 2\
**Last updated:** [June 15, 2020, 8:31am UTC](https://discourse.julialang.org/t/creating-an-anonymous-function-taking-as-arguments-the-elements-in-a-vector/41373 "2020-06-15T08:31:36Z")

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Hi Julians I have a vector vector\_symbol that contains a variable number of elements of type Symbol. I also have the variable ex of type Expr that is an expression of the Symbol elements in vector\_symbol. For example: …

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## [How to set @variable(m, tau\[1:N\] \>0 ) with JuMP](https://discourse.julialang.org/t/how-to-set-variable-m-tau-1-n-0-with-jump/41244)

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**Author:** [@namch](https://discourse.julialang.org/u/namch)\
**Replies:** 4\
**Last updated:** [June 15, 2020, 8:10am UTC](https://discourse.julialang.org/t/how-to-set-variable-m-tau-1-n-0-with-jump/41244 "2020-06-15T08:10:45Z")

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I get an error when trying to set variables larger than zero. Is there any way to over come this? ERROR: LoadError: LoadError: In @variable(m, tau\[1:N\] \> 0): Unknown sense \> Thank you

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## [Julia Starter Pack](https://discourse.julialang.org/t/julia-starter-pack/41359)

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**Author:** [@SubhadityaMukherjee](https://discourse.julialang.org/u/SubhadityaMukherjee)\
**Replies:** 2\
**Last updated:** [June 15, 2020, 7:33am UTC](https://discourse.julialang.org/t/julia-starter-pack/41359 "2020-06-15T07:33:00Z")

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Hello! I started with Julia maybe 3 weeks back and I have made a repository with everything that has helped me to get here. (And more). Hopefully, it will be of help to the community. A starter pack if you will. Reposi…

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## [The Euler and improved Euler methods](https://discourse.julialang.org/t/the-euler-and-improved-euler-methods/41404)

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**Author:** [@A.U.M](https://discourse.julialang.org/u/A.U.M)\
**Replies:** 1\
**Last updated:** [June 15, 2020, 4:23am UTC](https://discourse.julialang.org/t/the-euler-and-improved-euler-methods/41404 "2020-06-15T04:23:38Z")

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Hello, I am working on some implementation for Euler and Improved Euler method. for the Euler method, it works well but for the improved version, I got some "character ignored due to Unicode error " and the result is tot…

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## [RHS and LHS inconsistency in indexing over constraints](https://discourse.julialang.org/t/rhs-and-lhs-inconsistency-in-indexing-over-constraints/41409)

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**Author:** [@barguzin](https://discourse.julialang.org/u/barguzin)\
**Replies:** 2\
**Last updated:** [June 15, 2020, 1:33am UTC](https://discourse.julialang.org/t/rhs-and-lhs-inconsistency-in-indexing-over-constraints/41409 "2020-06-15T01:33:34Z")

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Hi folks, This is my first time using Julia for math optimization (was previously running Xpress FICO). I am trying to run a relatively easy anti-covering model. But I am running into issue with indices (or something e…

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## [Vcat slow?](https://discourse.julialang.org/t/vcat-slow/40579)

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**Author:** [@Ronneesley](https://discourse.julialang.org/u/Ronneesley)\
**Replies:** 12\
**Last updated:** [June 15, 2020, 12:47am UTC](https://discourse.julialang.org/t/vcat-slow/40579 "2020-06-15T00:47:53Z")

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Hello, I’m using vcat() to concatenate many vectors, but I observed that @code\_warntype it’s returning a red mark. I marked with \*\*\* in the code below: julia\> a = collect(1:10); julia\> b = collect(20:30); julia\> @cod…

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## [LoadError: MethodError: no method matching mdflatten](https://discourse.julialang.org/t/loaderror-methoderror-no-method-matching-mdflatten/24099)

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**Author:** [@etorkia](https://discourse.julialang.org/u/etorkia)\
**Replies:** 2\
**Last updated:** [June 15, 2020, 12:05am UTC](https://discourse.julialang.org/t/loaderror-methoderror-no-method-matching-mdflatten/24099 "2020-06-15T00:05:45Z")

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I am trying to run the Make.JL script but when it stream the markdown into Documenter, something is breaking and I don’t know where to look. I checked the Docstrings and the look ok…Any thoughts on how to interpret the m…

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## [Error Installing juno-client](https://discourse.julialang.org/t/error-installing-juno-client/41416)

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**Author:** [@ojo](https://discourse.julialang.org/u/ojo)\
**Replies:** 0\
**Last updated:** [June 14, 2020, 11:54pm UTC](https://discourse.julialang.org/t/error-installing-juno-client/41416 "2020-06-14T23:54:27Z")

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Hi everyone! This is my first time of using Julia. I tried installing juno in Atom using uber-juno. This is the error I get. Error installing juno-client. Check your internet or or report this to http://discuss.junolab…

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## [How do I tell the VSCode Langauge server to use my Project.toml?](https://discourse.julialang.org/t/how-do-i-tell-the-vscode-langauge-server-to-use-my-project-toml/41415)

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**Author:** [@oconnore](https://discourse.julialang.org/u/oconnore)\
**Replies:** 0\
**Last updated:** [June 14, 2020, 11:45pm UTC](https://discourse.julialang.org/t/how-do-i-tell-the-vscode-langauge-server-to-use-my-project-toml/41415 "2020-06-14T23:45:52Z")

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I have a project that I’m trying to edit in VSCode: eric@tara ~/s/c/sql\_explore (dev)\> tree . ├── Manifest.toml ├── Project.toml ├── main.jl ├── src │ └── sql\_explore.jl └── test └── runtests.jl The VSCode langua…

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## [A slight flaw in the Project/Manifest/Env logic?](https://discourse.julialang.org/t/a-slight-flaw-in-the-project-manifest-env-logic/41398)

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**Author:** [@affans](https://discourse.julialang.org/u/affans)\
**Replies:** 7\
**Last updated:** [June 14, 2020, 10:59pm UTC](https://discourse.julialang.org/t/a-slight-flaw-in-the-project-manifest-env-logic/41398 "2020-06-14T22:59:06Z")

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This post may seem long, but its a very step-by-step process and very easy to digest. Lets say I have developed a package (or more of a scientific simulation model) that depends on certain DataFrames, v0.20.2. The Proje…

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## [Debugger and Vega Plotting questions in Julia 1.4.1](https://discourse.julialang.org/t/debugger-and-vega-plotting-questions-in-julia-1-4-1/38705)

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**Author:** [@Clark\_Cruz](https://discourse.julialang.org/u/Clark_Cruz)\
**Replies:** 6\
**Last updated:** [June 14, 2020, 10:48pm UTC](https://discourse.julialang.org/t/debugger-and-vega-plotting-questions-in-julia-1-4-1/38705 "2020-06-14T22:48:05Z")

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Hi folks, I am moving away from Atom… and have installed VS code and the Julia extension. I am in Julia 1.4.1 The debugger extension is not doing anything. How do we Vega graph in the VS code? that is @vlplot in Qu…

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## [Heat / diffusion equation with co-ordinate dependent diffusion coefficient](https://discourse.julialang.org/t/heat-diffusion-equation-with-co-ordinate-dependent-diffusion-coefficient/41380)

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**Author:** [@Eben60](https://discourse.julialang.org/u/Eben60)\
**Replies:** 7\
**Last updated:** [June 14, 2020, 9:16pm UTC](https://discourse.julialang.org/t/heat-diffusion-equation-with-co-ordinate-dependent-diffusion-coefficient/41380 "2020-06-14T21:16:05Z")

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I am starting with the example at DiffEqOperators . I am interested in the steady state only. Let us have Neumann border condition (physically, a constant source of e.g. heat) on the left, and Dirichlet BC on the right. …

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## [Multidimentional integrals in julia: speed and automatic differentiation](https://discourse.julialang.org/t/multidimentional-integrals-in-julia-speed-and-automatic-differentiation/41375)

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**Author:** [@misha\_mikhasenko](https://discourse.julialang.org/u/misha_mikhasenko)\
**Replies:** 9\
**Last updated:** [June 14, 2020, 8:16pm UTC](https://discourse.julialang.org/t/multidimentional-integrals-in-julia-speed-and-automatic-differentiation/41375 "2020-06-14T20:16:14Z")

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I would like to differentiate through a two-dimensional integral. seems to be not possible for c++ wrappers (e.g. with the great Cuba.jl) Julia native integrators are way slower (HCubature.jl, NIntegration.jl) nested Q…

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## [Loading .txt files into an array](https://discourse.julialang.org/t/loading-txt-files-into-an-array/41370)

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**Author:** [@Fathya.Salih](https://discourse.julialang.org/u/Fathya.Salih)\
**Replies:** 4\
**Last updated:** [June 14, 2020, 7:04pm UTC](https://discourse.julialang.org/t/loading-txt-files-into-an-array/41370 "2020-06-14T19:04:28Z")

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Hi there, I am having trouble using the function readdlm(“file path”) from DelimitedFiles in a vscode .jl tab. I have the following code structure: # Test.jl using DelimitedFiles # function definitions # Defining cons…

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## [\[ANN\] MPFR\_wrap.jl](https://discourse.julialang.org/t/ann-mpfr-wrap-jl/41372)

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**Author:** [@mzaffalon](https://discourse.julialang.org/u/mzaffalon)\
**Replies:** 11\
**Last updated:** [June 14, 2020, 6:43pm UTC](https://discourse.julialang.org/t/ann-mpfr-wrap-jl/41372 "2020-06-14T18:43:29Z")

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Hello everyone, I would like to announce MPFR\_wrap.jl, a set of wrappers around MPFR, a multiple-precision floating-point library for in-place computation. MPFR\_wrap.jl does not introduce new types and makes instead use…

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## [How to check for packages updates without actually installing them](https://discourse.julialang.org/t/how-to-check-for-packages-updates-without-actually-installing-them/32498)

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**Author:** [@Jacky](https://discourse.julialang.org/u/Jacky)\
**Replies:** 4\
**Last updated:** [June 14, 2020, 6:24pm UTC](https://discourse.julialang.org/t/how-to-check-for-packages-updates-without-actually-installing-them/32498 "2020-06-14T18:24:54Z")

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Hi, currently I am using the Pkg.update() to check for available packages updates. However, Pkg.update() also automatically install the missing updates. Is there a way to check for package updates without installing them…

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## [Vector and integer variables](https://discourse.julialang.org/t/vector-and-integer-variables/41349)

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**Author:** [@Marques](https://discourse.julialang.org/u/Marques)\
**Replies:** 7\
**Last updated:** [June 14, 2020, 6:07pm UTC](https://discourse.julialang.org/t/vector-and-integer-variables/41349 "2020-06-14T18:07:49Z")

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Hi guys, could you help me please? I came across a problem and I can’t imagine a way out. How do I compare an integer value passed as a parameter to a function, for example: x = 123 and find out if the values of x exist …

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## [FFTW fails to build](https://discourse.julialang.org/t/fftw-fails-to-build/41392)

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**Author:** [@ctkelley](https://discourse.julialang.org/u/ctkelley)\
**Replies:** 1\
**Last updated:** [June 14, 2020, 5:44pm UTC](https://discourse.julialang.org/t/fftw-fails-to-build/41392 "2020-06-14T17:44:01Z")

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I did an \] update and FFTW failed with this message (@v1.4) pkg\> build FFTW Building FFTW → ~/.julia/packages/FFTW/kcXL6/deps/build.log ┌ Error: Error building FFTW: │ ERROR: LoadError: ArgumentError: Package Li…

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## [Different result with PeriodicCallback](https://discourse.julialang.org/t/different-result-with-periodiccallback/41273)

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**Author:** [@ohmsweetohm1](https://discourse.julialang.org/u/ohmsweetohm1)\
**Replies:** 13\
**Last updated:** [June 14, 2020, 4:47pm UTC](https://discourse.julialang.org/t/different-result-with-periodiccallback/41273 "2020-06-14T16:47:34Z")

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I am trieing to understand the PeriodicCallback method and noticed something weird. using DifferentialEquations, PyPlot mutable struct SimType{T} \<: DEDataVector{T} x::Vector{T} a::T end f1(du, u, p, t) = du\[1…

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## [Accessing elements in Gtk container by name](https://discourse.julialang.org/t/accessing-elements-in-gtk-container-by-name/41385)

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**Author:** [@Christopher\_Fisher](https://discourse.julialang.org/u/Christopher_Fisher)\
**Replies:** 0\
**Last updated:** [June 14, 2020, 3:29pm UTC](https://discourse.julialang.org/t/accessing-elements-in-gtk-container-by-name/41385 "2020-06-14T15:29:01Z")

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In Gtk.jl, elements are accessed by an integer index. For example, using Gtk win = GtkWindow() button = GtkButton("OK", name="ok\_button") push!(win, button) win\[1\] This has two limitations in my opinion. First, integer…

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## [JSON.parsefile() returning load error Unexpected Character](https://discourse.julialang.org/t/json-parsefile-returning-load-error-unexpected-character/41338)

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**Author:** [@waqas](https://discourse.julialang.org/u/waqas)\
**Replies:** 6\
**Last updated:** [June 14, 2020, 3:26pm UTC](https://discourse.julialang.org/t/json-parsefile-returning-load-error-unexpected-character/41338 "2020-06-14T15:26:15Z")

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Hi, I am trying to follow the tutorials on “Julia for Data science” and am getting Unexpected Character error whenever I try to use JSON.parsefile(). I have tried many different JSON files but, the error still pops up. …

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## [Julia save ".rdata" equivalent](https://discourse.julialang.org/t/julia-save-rdata-equivalent/41326)

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**Author:** [@laut](https://discourse.julialang.org/u/laut)\
**Replies:** 6\
**Last updated:** [June 14, 2020, 2:40pm UTC](https://discourse.julialang.org/t/julia-save-rdata-equivalent/41326 "2020-06-14T14:40:39Z")

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I can’t find a consensus for what would be a good .rdata file equivalent. I like rdata files because they are very compact and I can throw multiple objects into them. Any suggestions?

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## [Generate equal length strings from numbers by padding with "0"?](https://discourse.julialang.org/t/generate-equal-length-strings-from-numbers-by-padding-with-0/41365)

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**Author:** [@Iulian.Cioarca](https://discourse.julialang.org/u/Iulian.Cioarca)\
**Replies:** 6\
**Last updated:** [June 14, 2020, 1:07pm UTC](https://discourse.julialang.org/t/generate-equal-length-strings-from-numbers-by-padding-with-0/41365 "2020-06-14T13:07:59Z")

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Let’s say I have an array of integers x = \[1, 14, 356\]. I want to generate individual strings, with equal lengths: x\_str = \[“001”, “014”, “356”\]. How can I achieve that? The background of the problem is the following…

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## [How to tell if A\*B hits BLAS?](https://discourse.julialang.org/t/how-to-tell-if-a-b-hits-blas/41303)

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**Author:** [@e3c6](https://discourse.julialang.org/u/e3c6)\
**Replies:** 2\
**Last updated:** [June 14, 2020, 11:43am UTC](https://discourse.julialang.org/t/how-to-tell-if-a-b-hits-blas/41303 "2020-06-14T11:43:53Z")

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Julia’s type system for linear algebra is quite sophisticated. I have a case where, after some reshape and transpose operations, I obtain two matrices A,B for which for some reason, A\*B falls back to the slow generic\_mat…

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## [Backpropagation Through Time](https://discourse.julialang.org/t/backpropagation-through-time/40822)

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**Author:** [@Freddy\_Chua](https://discourse.julialang.org/u/Freddy_Chua)\
**Replies:** 1\
**Last updated:** [June 14, 2020, 10:50am UTC](https://discourse.julialang.org/t/backpropagation-through-time/40822 "2020-06-14T10:50:58Z")

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Hi, I noted the used of “record” for BPTT for LSTM/Recurrence based Models. Is this in used? I don’t see it being documented anywhere, i also could not find it in the code. How do we do BPTT?

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## [How to execute echo $PATH from Julia](https://discourse.julialang.org/t/how-to-execute-echo-path-from-julia/41364)

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**Author:** [@pauljurczak](https://discourse.julialang.org/u/pauljurczak)\
**Replies:** 2\
**Last updated:** [June 14, 2020, 10:49am UTC](https://discourse.julialang.org/t/how-to-execute-echo-path-from-julia/41364 "2020-06-14T10:49:16Z")

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I would like to run echo $PATH bash command, see the result and optionally capture it in a string or array of strings. I started with: julia\> run(\`echo $PATH\`) ERROR: UndefVarError: PATH not defined julia\> run(\`echo \\$P…

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## [Eigensolver for interior eigenvalues of sparse (banded) Hermitian matrices?](https://discourse.julialang.org/t/eigensolver-for-interior-eigenvalues-of-sparse-banded-hermitian-matrices/41360)

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**Author:** [@Grayscale](https://discourse.julialang.org/u/Grayscale)\
**Replies:** 3\
**Last updated:** [June 14, 2020, 8:54am UTC](https://discourse.julialang.org/t/eigensolver-for-interior-eigenvalues-of-sparse-banded-hermitian-matrices/41360 "2020-06-14T08:54:50Z")

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I am trying to compute many interior eigenvalues of large sparse banded complex Hermitian matrices. By the way, the (absolute value of the) matrix looks like this for the ~1500 by ~1500 case: Here, ~ 98.8% of the el…

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## [Reading parquet very slow](https://discourse.julialang.org/t/reading-parquet-very-slow/41344)

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**Author:** [@freeman](https://discourse.julialang.org/u/freeman)\
**Replies:** 4\
**Last updated:** [June 14, 2020, 8:48am UTC](https://discourse.julialang.org/t/reading-parquet-very-slow/41344 "2020-06-14T08:48:59Z")

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I have a parquet file, about 100mb compressed. In python, reading it with pd.read\_parquet(path) takes about 1 second. The file is 12GB in memory. In Julia this: using DataFrames, ParquetFiles df = DataFrame(lo…

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