# General Usage

**URL:** https://discourse.julialang.org/c/usage/6.md?page=525

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

**Page:** 526

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## [Unsatisfiable requirements detected for package OpenBLAS\_jll (error indirectly from PackageCompiler)](https://discourse.julialang.org/t/unsatisfiable-requirements-detected-for-package-openblas-jll-error-indirectly-from-packagecompiler/70811)

<div class="topic-metadata">

**Author:** [@Palli](https://discourse.julialang.org/u/Palli)\
**Replies:** 3\
**Last updated:** [November 2, 2021, 4:21pm UTC](https://discourse.julialang.org/t/unsatisfiable-requirements-detected-for-package-openblas-jll-error-indirectly-from-packagecompiler/70811 "2021-11-02T16:21:55Z")

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Any idea why this seeming MWE doesn’t work (confirmed below, is a known bug in 1.8): (@v1.8) pkg\> add OpenBLAS\_jll@v0.3.13 Resolving package versions... ERROR: Unsatisfiable requirements detected for package OpenBLAS…

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## [VideoIO.jl don't recognizes encodevideo() function anymore](https://discourse.julialang.org/t/videoio-jl-dont-recognizes-encodevideo-function-anymore/58479)

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**Author:** [@Renan\_Rabelo](https://discourse.julialang.org/u/Renan_Rabelo)\
**Replies:** 5\
**Last updated:** [November 2, 2021, 4:12pm UTC](https://discourse.julialang.org/t/videoio-jl-dont-recognizes-encodevideo-function-anymore/58479 "2021-11-02T16:12:56Z")

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Hi, Last week I was using VideoIO.jl package and everything was normal. Today I tried to encode a video and the function simply doesn’t exists anymore. I searched in the GitHub page and noticed that the last update was…

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## [Distributing loops across threads manually (something like OpenMP)](https://discourse.julialang.org/t/distributing-loops-across-threads-manually-something-like-openmp/70701)

<div class="topic-metadata">

**Author:** [@tgautam03](https://discourse.julialang.org/u/tgautam03)\
**Replies:** 14\
**Last updated:** [November 2, 2021, 4:09pm UTC](https://discourse.julialang.org/t/distributing-loops-across-threads-manually-something-like-openmp/70701 "2021-11-02T16:09:00Z")

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Hi, I’m quite familiar with the workings of OpenMP and have understood the parallel programming concepts using Fork Join Model. I’m just starting out with julia and was hoping to understand multithreading in julia better…

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## [(discrete cosine transform) DCT on GPU](https://discourse.julialang.org/t/discrete-cosine-transform-dct-on-gpu/64273)

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**Author:** [@rveltz](https://discourse.julialang.org/u/rveltz)\
**Replies:** 4\
**Last updated:** [November 2, 2021, 3:44pm UTC](https://discourse.julialang.org/t/discrete-cosine-transform-dct-on-gpu/64273 "2021-11-02T15:44:38Z")

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Hi, Although I have discussed some of this with some developers at Oceananigans.jl, I am reaching you out here to ask if anybody has a plan\_dct! which works on GPU? Should we parallel FFTW.jl? Thank you, Bests

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## [Jupyter notebook -- disappearing cells?](https://discourse.julialang.org/t/jupyter-notebook-disappearing-cells/70726)

<div class="topic-metadata">

**Author:** [@BLI](https://discourse.julialang.org/u/BLI)\
**Replies:** 7\
**Last updated:** [November 2, 2021, 3:07pm UTC](https://discourse.julialang.org/t/jupyter-notebook-disappearing-cells/70726 "2021-11-02T15:07:31Z")

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I had a Jupyter notebook running in my browser, and suddenly I was told that there was a problem with connection to the server. It seemed like Julia had crashed… When I open notebooks after that, some cells don’t show i…

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## [Julia program aborting when trying to run KrylovKit.svdsolve](https://discourse.julialang.org/t/julia-program-aborting-when-trying-to-run-krylovkit-svdsolve/70809)

<div class="topic-metadata">

**Author:** [@iamsuddhasattwa](https://discourse.julialang.org/u/iamsuddhasattwa)\
**Replies:** 0\
**Last updated:** [November 2, 2021, 2:52pm UTC](https://discourse.julialang.org/t/julia-program-aborting-when-trying-to-run-krylovkit-svdsolve/70809 "2021-11-02T14:52:15Z")

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I am trying to execute a simple SVD computation using the KrylovKit.svdsolve function. However not only does Julia report an error, but the program also terminates. It seems to me to be a problem with both the package as…

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## [Add deepcopy operator := to avoid bugs](https://discourse.julialang.org/t/add-deepcopy-operator-to-avoid-bugs/70793)

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**Author:** [@martin.demare](https://discourse.julialang.org/u/martin.demare)\
**Replies:** 7\
**Last updated:** [November 2, 2021, 11:41am UTC](https://discourse.julialang.org/t/add-deepcopy-operator-to-avoid-bugs/70793 "2021-11-02T11:41:20Z")

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When doing everyday data analysis, avoiding bugs is often more time saving than having great code performance. One of my reoccurring bugs is that I forget that z=x doesn’t create a copy of x if x is an array. Therefo…

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## [Genie multi-instance](https://discourse.julialang.org/t/genie-multi-instance/70798)

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**Author:** [@HANHAOHAN](https://discourse.julialang.org/u/HANHAOHAN)\
**Replies:** 0\
**Last updated:** [November 2, 2021, 10:55am UTC](https://discourse.julialang.org/t/genie-multi-instance/70798 "2021-11-02T10:55:51Z")

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How to use Genie multiprocess or multithread to use multi-core cpu

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## [How can I parallelize my Neural Network training](https://discourse.julialang.org/t/how-can-i-parallelize-my-neural-network-training/70771)

<div class="topic-metadata">

**Author:** [@oijoij](https://discourse.julialang.org/u/oijoij)\
**Replies:** 0\
**Last updated:** [November 2, 2021, 1:05am UTC](https://discourse.julialang.org/t/how-can-i-parallelize-my-neural-network-training/70771 "2021-11-02T01:05:05Z")

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Hello, new here. Sorry if I make any mistakes. I am currently trying to train a Neural Network to approximate a function. However it is not fast enough, and I think the most obvious gains can come from parallelizing. S…

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## [The bin2 function](https://discourse.julialang.org/t/the-bin2-function/70488)

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**Author:** [@marouane](https://discourse.julialang.org/u/marouane)\
**Replies:** 7\
**Last updated:** [November 1, 2021, 9:06pm UTC](https://discourse.julialang.org/t/the-bin2-function/70488 "2021-11-01T21:06:46Z")

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I am looking at a code of an early version of Julia and there is this function, bin2() that I don’t know what is it for specially I can’t see the output how can I write in Julia 1.5 ?

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## [Improving the start banner with BetterBanner.jl](https://discourse.julialang.org/t/improving-the-start-banner-with-betterbanner-jl/70711)

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**Author:** [@longemen3000](https://discourse.julialang.org/u/longemen3000)\
**Replies:** 8\
**Last updated:** [November 1, 2021, 1:19pm UTC](https://discourse.julialang.org/t/improving-the-start-banner-with-betterbanner-jl/70711 "2021-11-01T13:19:14Z")

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All started in the Humans of Julia discord server, when one user was showcasing julia on a mobile device, and one thing that standed out was that the start banner text overflows, ruining the julia logo. A similar thing …

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## [A \* B \* A' is not hermitian, even when B is](https://discourse.julialang.org/t/a-b-a-is-not-hermitian-even-when-b-is/70611)

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**Author:** [@jlbosse](https://discourse.julialang.org/u/jlbosse)\
**Replies:** 8\
**Last updated:** [November 1, 2021, 1:17pm UTC](https://discourse.julialang.org/t/a-b-a-is-not-hermitian-even-when-b-is/70611 "2021-11-01T13:17:11Z")

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The title essentially says it all: If I create a hermitian matrix A with julia\> R = randn(10,10) julia\> A = R \* R' # definitely hermitian and positive semidefinite and another arbitrary matrix B julia\> B = rand(7, 10…

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## [Question about UMAP](https://discourse.julialang.org/t/question-about-umap/70733)

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**Author:** [@abcde](https://discourse.julialang.org/u/abcde)\
**Replies:** 1\
**Last updated:** [November 1, 2021, 1:10pm UTC](https://discourse.julialang.org/t/question-about-umap/70733 "2021-11-01T13:10:05Z")

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I performed the following operations, but Julia reported an error \]add UMAP ERROR: Unsatisfiable requirements detected for package Reexport \[189a3867\]: Reexport \[189a3867\] log: ├─possible versions are: 0.2.0-1.2.2 or…

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## [Get true maximum value of a raster](https://discourse.julialang.org/t/get-true-maximum-value-of-a-raster/70622)

<div class="topic-metadata">

**Author:** [@CompulsoryCoffee](https://discourse.julialang.org/u/CompulsoryCoffee)\
**Replies:** 4\
**Last updated:** [November 1, 2021, 11:25am UTC](https://discourse.julialang.org/t/get-true-maximum-value-of-a-raster/70622 "2021-11-01T11:25:41Z")

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Hi, I have raster which I would like to get the maximum value from using ArchGDAL but I get only the (I believe 98th percentile (as it is done in QGIS) using ArchGDAL const AG = ArchGDAL dataset = AG.readraster("rast…

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## [Qt platform plugin required for PyPlot](https://discourse.julialang.org/t/qt-platform-plugin-required-for-pyplot/70725)

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**Author:** [@mzaffalon](https://discourse.julialang.org/u/mzaffalon)\
**Replies:** 0\
**Last updated:** [November 1, 2021, 9:48am UTC](https://discourse.julialang.org/t/qt-platform-plugin-required-for-pyplot/70725 "2021-11-01T09:48:19Z")

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I have removed the .julia directory and used Pkg package manager to install PyPlot only in Julia 1.6.3 on a Windows machine. qt.qpa.plugin returns an error. julia\> versioninfo() Julia Version 1.6.3 Commit ae8452a9e0 (20…

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## [Reversing Axis of the plot](https://discourse.julialang.org/t/reversing-axis-of-the-plot/58604)

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**Author:** [@tgautam03](https://discourse.julialang.org/u/tgautam03)\
**Replies:** 1\
**Last updated:** [November 1, 2021, 5:51am UTC](https://discourse.julialang.org/t/reversing-axis-of-the-plot/58604 "2021-11-01T05:51:06Z")

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Hi, I’m plotting using Plots and noticed that by default 0,0 is at bottom left. Is there any way by which I can move this to top left (i.e. reverse y-axis). Thanks

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## [Cannot start Julia 1.7 rc2](https://discourse.julialang.org/t/cannot-start-julia-1-7-rc2/70629)

<div class="topic-metadata">

**Author:** [@matthieu](https://discourse.julialang.org/u/matthieu)\
**Replies:** 1\
**Last updated:** [October 29, 2021, 9:24pm UTC](https://discourse.julialang.org/t/cannot-start-julia-1-7-rc2/70629 "2021-10-29T21:24:23Z")

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I cannot launch Julia 1.7 rc2 after updating to Monterey (macOS 12.0). When I try to launch it in the Terminal, I get the error: fatal: error thrown and no exception handler available. InitError(mod=:Sys, error=ErrorExc…

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## [Turing models: Errors when generating random numbers using parameters (Tracked reals)](https://discourse.julialang.org/t/turing-models-errors-when-generating-random-numbers-using-parameters-tracked-reals/70702)

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**Author:** [@dlakelan](https://discourse.julialang.org/u/dlakelan)\
**Replies:** 0\
**Last updated:** [October 31, 2021, 8:28pm UTC](https://discourse.julialang.org/t/turing-models-errors-when-generating-random-numbers-using-parameters-tracked-reals/70702 "2021-10-31T20:28:34Z")

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Inside a Turing model, for some generated quantities, I’m doing rand(Normal(0.0,scale)) where “scale” is a parameter. I’m getting an error: ERROR: LoadError: MethodError: no method matching randn(::Random.\_GLOBAL\_RNG, …

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## [For loop optimization](https://discourse.julialang.org/t/for-loop-optimization/70700)

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**Author:** [@claudio20497](https://discourse.julialang.org/u/claudio20497)\
**Replies:** 3\
**Last updated:** [October 31, 2021, 7:39pm UTC](https://discourse.julialang.org/t/for-loop-optimization/70700 "2021-10-31T19:39:39Z")

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Hello, I’m not sure how to optimize the following for loop. array\_1 and array\_2 are two Vector{Vector{Int64}}s, and I’m interested in evaluating which combinations (of 2 elements) of their vector components has an elem…

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## [Parallelization of for loop](https://discourse.julialang.org/t/parallelization-of-for-loop/70557)

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**Author:** [@Germinator](https://discourse.julialang.org/u/Germinator)\
**Replies:** 3\
**Last updated:** [October 31, 2021, 7:52pm UTC](https://discourse.julialang.org/t/parallelization-of-for-loop/70557 "2021-10-31T19:52:45Z")

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Dear Julia users, I am trying to parallelize the following loop, what do you think is the best approach? for n = 1:N kron!(temp,A\[n,:\],B\[n,:\]) C.+= temp.\*temp' Cx .+= tem…

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## [Understanding how an array of structures works](https://discourse.julialang.org/t/understanding-how-an-array-of-structures-works/46011)

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**Author:** [@rjmoses](https://discourse.julialang.org/u/rjmoses)\
**Replies:** 31\
**Last updated:** [October 31, 2021, 6:14pm UTC](https://discourse.julialang.org/t/understanding-how-an-array-of-structures-works/46011 "2021-10-31T18:14:17Z")

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I tripped across something that I just plain don’t understand when using an array to contain a structure. If I have a structure created outside a for loop and try to assign it to an element of the array, I do not get t…

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## [Conditionally defining a macro](https://discourse.julialang.org/t/conditionally-defining-a-macro/70690)

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**Author:** [@Mark\_Nahabedian](https://discourse.julialang.org/u/Mark_Nahabedian)\
**Replies:** 1\
**Last updated:** [October 31, 2021, 4:37pm UTC](https://discourse.julialang.org/t/conditionally-defining-a-macro/70690 "2021-10-31T16:37:20Z")

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I want to be able to modify a bunch of definitions depending on whether another file is included. In the parlance of Aspect Oriented programming, that file would implement an aspect which I could optionally include. I …

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## [Best practice for temporarily loading a package without polluting Manifest.toml and Project.toml?](https://discourse.julialang.org/t/best-practice-for-temporarily-loading-a-package-without-polluting-manifest-toml-and-project-toml/70693)

<div class="topic-metadata">

**Author:** [@robsmith11](https://discourse.julialang.org/u/robsmith11)\
**Replies:** 1\
**Last updated:** [October 31, 2021, 3:50pm UTC](https://discourse.julialang.org/t/best-practice-for-temporarily-loading-a-package-without-polluting-manifest-toml-and-project-toml/70693 "2021-10-31T15:50:35Z")

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Say I’m working on a project and want to plot something so I add a plotting package for looking at some test data. But when my package is actually built and deployed, I don’t want the plotting package and all of its dep…

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## [What is your favorite mapping package?](https://discourse.julialang.org/t/what-is-your-favorite-mapping-package/70509)

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**Author:** [@leon](https://discourse.julialang.org/u/leon)\
**Replies:** 31\
**Last updated:** [October 31, 2021, 3:31pm UTC](https://discourse.julialang.org/t/what-is-your-favorite-mapping-package/70509 "2021-10-31T15:31:08Z")

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My requirements are: Capable of plotting filled contours in the ocean Land areas can be filled with the color of my choice I can choose different mapping projections. There are lots of sample codes available I’m sure …

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## [Automatically close "Julia Debugger" terminal after program ends](https://discourse.julialang.org/t/automatically-close-julia-debugger-terminal-after-program-ends/56351)

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**Author:** [@luc-j-bourhis](https://discourse.julialang.org/u/luc-j-bourhis)\
**Replies:** 1\
**Last updated:** [October 31, 2021, 2:46pm UTC](https://discourse.julialang.org/t/automatically-close-julia-debugger-terminal-after-program-ends/56351 "2021-10-31T14:46:45Z")

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By default, every time a debug session is started, a new terminal “Julia Debugger” is started. When the program finishes, one has to hit “enter” to close it as instructed by the message “Julia debuggee finished. Press EN…

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## [Why does the command \`run\` fails in this example from the documentation?](https://discourse.julialang.org/t/why-does-the-command-run-fails-in-this-example-from-the-documentation/70686)

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**Author:** [@Soldalma](https://discourse.julialang.org/u/Soldalma)\
**Replies:** 1\
**Last updated:** [October 31, 2021, 1:32pm UTC](https://discourse.julialang.org/t/why-does-the-command-run-fails-in-this-example-from-the-documentation/70686 "2021-10-31T13:32:22Z")

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I am trying to learn how to issue shell commands from my Julia program. My OS is Windows 10 but I would also like the commands to run under Linux (Kubuntu). I found the following in the documentation: julia\> mycommand =…

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## [NeuralPDE.NNODE ODE system solve](https://discourse.julialang.org/t/neuralpde-nnode-ode-system-solve/70538)

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**Author:** [@Dr\_M\_Umut\_DEMiREZEN](https://discourse.julialang.org/u/Dr_M_Umut_DEMiREZEN)\
**Replies:** 2\
**Last updated:** [October 31, 2021, 12:15pm UTC](https://discourse.julialang.org/t/neuralpde-nnode-ode-system-solve/70538 "2021-10-31T12:15:41Z")

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Hi, I wanted to use NeuralPDE.NNODE function to solve a coupled ODE system (4 ODE equations) The code is given below : (not given completely) @parameters t @variables k(t) r(t) p(t) c(t) D = Differential(t) eqs = \[D…

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## [Best practices for "base" packages to define common function names?](https://discourse.julialang.org/t/best-practices-for-base-packages-to-define-common-function-names/70674)

<div class="topic-metadata">

**Author:** [@Alec\_Loudenback](https://discourse.julialang.org/u/Alec_Loudenback)\
**Replies:** 2\
**Last updated:** [October 31, 2021, 6:45am UTC](https://discourse.julialang.org/t/best-practices-for-base-packages-to-define-common-function-names/70674 "2021-10-31T06:45:02Z")

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I have a couple of packages that have functions with the same name, but operate on different structs. Users could definitely have both packages loaded at the same time. I think the best way to prevent issues from confli…

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## [Does the GMT.jl package conflict with the MAT.jl and NCDatasets.jl packages?](https://discourse.julialang.org/t/does-the-gmt-jl-package-conflict-with-the-mat-jl-and-ncdatasets-jl-packages/70639)

<div class="topic-metadata">

**Author:** [@leon](https://discourse.julialang.org/u/leon)\
**Replies:** 13\
**Last updated:** [October 30, 2021, 11:46pm UTC](https://discourse.julialang.org/t/does-the-gmt-jl-package-conflict-with-the-mat-jl-and-ncdatasets-jl-packages/70639 "2021-10-30T23:46:55Z")

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I have a very weird situation. I can plot a map using my GMT.jl package. I can also load my NetCDF data using NCDatasets.jl without any issues. However, if I first use NCDatasets.jl to load the data in and then use GMT.…

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## [Getting original array index from its view with reduced dimensions](https://discourse.julialang.org/t/getting-original-array-index-from-its-view-with-reduced-dimensions/46822)

<div class="topic-metadata">

**Author:** [@pauljurczak](https://discourse.julialang.org/u/pauljurczak)\
**Replies:** 6\
**Last updated:** [October 30, 2021, 7:17pm UTC](https://discourse.julialang.org/t/getting-original-array-index-from-its-view-with-reduced-dimensions/46822 "2021-10-30T19:17:37Z")

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In this code: a = reshape(collect(1:12), 4, 3) v = view(a, 2, :) for i in eachindex(v) # print corresponding index of array a end I would like to get corresponding original indices of array a, either linear or Carte…

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