# New to Julia

**URL:** https://discourse.julialang.org/c/first-steps/8.md?page=42

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**Page:** 43

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## [Neural Networks to describe binary-black-holes trajectories](https://discourse.julialang.org/t/neural-networks-to-describe-binary-black-holes-trajectories/115769)

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**Author:** [@Jose\_P](https://discourse.julialang.org/u/Jose_P)\
**Replies:** 4\
**Last updated:** [June 18, 2024, 4:37pm UTC](https://discourse.julialang.org/t/neural-networks-to-describe-binary-black-holes-trajectories/115769 "2024-06-18T16:37:32Z")

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Hello everyone! I am new to Julia and currently working on a project that involves using neural networks to describe geodesics around a black hole. I am encountering an error ‘type Array has no field layer\_1,’ and I am u…

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## [InexactError: Int64](https://discourse.julialang.org/t/inexacterror-int64/115803)

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**Author:** [@evansenvy](https://discourse.julialang.org/u/evansenvy)\
**Replies:** 2\
**Last updated:** [June 18, 2024, 12:54pm UTC](https://discourse.julialang.org/t/inexacterror-int64/115803 "2024-06-18T12:54:12Z")

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Hi, I am encountering this error- InexactError: Int64. InexactError: Int64(2.5) When I search for this I got this article \[unrelated blogspam link redacted\] and as per this, explaining an answer in which they are talk…

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## [Problems with Agent constructors](https://discourse.julialang.org/t/problems-with-agent-constructors/115761)

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**Author:** [@stefkuypers](https://discourse.julialang.org/u/stefkuypers)\
**Replies:** 8\
**Last updated:** [June 18, 2024, 9:34am UTC](https://discourse.julialang.org/t/problems-with-agent-constructors/115761 "2024-06-18T09:34:28Z")

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I’m probably not seeing something obvious but for some reason I have one Agent for which the constructor works and another one for which I get an error when I try to call the constructor and I have no clue why. Here is …

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## [Simple transformation of a dataframe with grouped data](https://discourse.julialang.org/t/simple-transformation-of-a-dataframe-with-grouped-data/115660)

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**Author:** [@sbacelar](https://discourse.julialang.org/u/sbacelar)\
**Replies:** 4\
**Last updated:** [June 17, 2024, 6:09pm UTC](https://discourse.julialang.org/t/simple-transformation-of-a-dataframe-with-grouped-data/115660 "2024-06-17T18:09:11Z")

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I am trying to transpose this R script to Julia without success: library(dplyr) culture \<- tibble( ind = c(1, 1, 1, 2, 2, 2), year = c(2015, 2015, 2015, 2016, 2016, 2016), value = c(10, 20, 30, 26, 34, 67) ) cul…

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## [Which concepts known from Python programming are useful in understanding Julia and which are not?](https://discourse.julialang.org/t/which-concepts-known-from-python-programming-are-useful-in-understanding-julia-and-which-are-not/115460)

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**Author:** [@oOosys](https://discourse.julialang.org/u/oOosys)\
**Replies:** 52\
**Last updated:** [June 17, 2024, 4:53pm UTC](https://discourse.julialang.org/t/which-concepts-known-from-python-programming-are-useful-in-understanding-julia-and-which-are-not/115460 "2024-06-17T16:53:20Z")

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Are there concepts ingrained by 30 years of using Pyhon in my brain which I need to throw away and get rid of because they will lead to issues with understanding how to read and write Julia code (except zero-based indexi…

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## [Allocations and time of running the same program twice are orders of magnitude larger than running them separately](https://discourse.julialang.org/t/allocations-and-time-of-running-the-same-program-twice-are-orders-of-magnitude-larger-than-running-them-separately/114078)

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**Author:** [@dieg0](https://discourse.julialang.org/u/dieg0)\
**Replies:** 11\
**Last updated:** [June 17, 2024, 12:58pm UTC](https://discourse.julialang.org/t/allocations-and-time-of-running-the-same-program-twice-are-orders-of-magnitude-larger-than-running-them-separately/114078 "2024-06-17T12:58:52Z")

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I am relatively new to Julia. I am building a code to optimize some objective function that is called many times. The most important intermediate step is computing the following function, called recover\_δ! which is a fix…

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## [Movie from data](https://discourse.julialang.org/t/movie-from-data/115739)

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**Author:** [@NaSi](https://discourse.julialang.org/u/NaSi)\
**Replies:** 4\
**Last updated:** [June 17, 2024, 12:05pm UTC](https://discourse.julialang.org/t/movie-from-data/115739 "2024-06-17T12:05:15Z")

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Hi there ! I am new on Julia, so I would appreciate your help. I have a data set called data : julia\> size(data) (4994, 50405) 4994 is the distance along an axis and 50405 is the time with : julia\> size(time\_test) …

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## [Can i start out with Julia as my 1st coding language](https://discourse.julialang.org/t/can-i-start-out-with-julia-as-my-1st-coding-language/115663)

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**Author:** [@Zorn\_thimmberglobber](https://discourse.julialang.org/u/Zorn_thimmberglobber)\
**Replies:** 7\
**Last updated:** [June 16, 2024, 11:08am UTC](https://discourse.julialang.org/t/can-i-start-out-with-julia-as-my-1st-coding-language/115663 "2024-06-16T11:08:26Z")

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Is it a good idea to learn Julia as my 1st coding language? If so what are some good beginner projects.

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## [Add time dependent terms in a differential equation](https://discourse.julialang.org/t/add-time-dependent-terms-in-a-differential-equation/113338)

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**Author:** [@Piyush](https://discourse.julialang.org/u/Piyush)\
**Replies:** 3\
**Last updated:** [June 15, 2024, 10:58am UTC](https://discourse.julialang.org/t/add-time-dependent-terms-in-a-differential-equation/113338 "2024-06-15T10:58:04Z")

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Hi, I am a new to Julia and trying to solve Differential Equation with exogenous inputs. The inputs will be read from data at discrete times. Can someone help with the minimal code for the same. I would also like to do …

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## [ImageView.imshow() crashes when playing with contrast values and crashing the REPL](https://discourse.julialang.org/t/imageview-imshow-crashes-when-playing-with-contrast-values-and-crashing-the-repl/115236)

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**Author:** [@Mend-Amar\_Badral](https://discourse.julialang.org/u/Mend-Amar_Badral)\
**Replies:** 4\
**Last updated:** [June 15, 2024, 4:52am UTC](https://discourse.julialang.org/t/imageview-imshow-crashes-when-playing-with-contrast-values-and-crashing-the-repl/115236 "2024-06-15T04:52:49Z")

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I’ve been trying to use the ImageView.jl package for viewing images from TestImages.jl package to see and playing around with the contrast slider.Specifically I used mri-stack.tif image. I think it has some bugs and issu…

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## [Agent based model - create scatter plot with agent variables from data frame](https://discourse.julialang.org/t/agent-based-model-create-scatter-plot-with-agent-variables-from-data-frame/115553)

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**Author:** [@tfranks](https://discourse.julialang.org/u/tfranks)\
**Replies:** 1\
**Last updated:** [June 15, 2024, 3:37am UTC](https://discourse.julialang.org/t/agent-based-model-create-scatter-plot-with-agent-variables-from-data-frame/115553 "2024-06-15T03:37:14Z")

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Hello, I’ve created an agent-based model where a Bank agent has randomly assigned variables of “uninsured,” "investments,"and “AFS\_securities” that are collected in a data frame after running. I now want to create a 3D…

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## [Trouble with running Julia scripts from within Geany](https://discourse.julialang.org/t/trouble-with-running-julia-scripts-from-within-geany/115519)

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**Author:** [@oOosys](https://discourse.julialang.org/u/oOosys)\
**Replies:** 6\
**Last updated:** [June 14, 2024, 4:49pm UTC](https://discourse.julialang.org/t/trouble-with-running-julia-scripts-from-within-geany/115519 "2024-06-14T16:49:53Z")

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$ /bin/sh /tmp/geany\_run\_script\_PDOCP2.sh /tmp/geany\_run\_script\_PDOCP2.sh: 7: ./delMe: not found delMe.jl is the script file and I have updated the filetypes.julia file with: \[build-menu\] run\_cmd=/home/o/.juliaup/bin/…

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## [Why am I unable to properly edit my environment variables?](https://discourse.julialang.org/t/why-am-i-unable-to-properly-edit-my-environment-variables/115631)

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**Author:** [@abcde](https://discourse.julialang.org/u/abcde)\
**Replies:** 9\
**Last updated:** [June 14, 2024, 7:36am UTC](https://discourse.julialang.org/t/why-am-i-unable-to-properly-edit-my-environment-variables/115631 "2024-06-14T07:36:44Z")

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thanks!

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## [Broadcast Vec{Matrix}](https://discourse.julialang.org/t/broadcast-vec-matrix/115632)

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**Author:** [@Cyan](https://discourse.julialang.org/u/Cyan)\
**Replies:** 1\
**Last updated:** [June 14, 2024, 3:10am UTC](https://discourse.julialang.org/t/broadcast-vec-matrix/115632 "2024-06-14T03:10:44Z")

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I have two vector of matrix AL = \[ A1, A2, ..., An \] and wL = \[ w1, w2, ..., wn \], I want to obtain the array of \[ A1.\*w1, ..., An.\*wn \], but AL.\* wL gives me \[ A1\*w1, ..., An\*wn \]. Is there any methods could make all th…

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## [Which code does in Julia script need to be written to make code from REPL running as script?](https://discourse.julialang.org/t/which-code-does-in-julia-script-need-to-be-written-to-make-code-from-repl-running-as-script/115599)

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**Author:** [@oOosys](https://discourse.julialang.org/u/oOosys)\
**Replies:** 4\
**Last updated:** [June 13, 2024, 7:53pm UTC](https://discourse.julialang.org/t/which-code-does-in-julia-script-need-to-be-written-to-make-code-from-repl-running-as-script/115599 "2024-06-13T19:53:41Z")

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What need to be explicit mentioned (written out as code) in a Julia script which does not need to be mentioned while using Julia REPL? It seems that for example code which runs in the REPL taken 1:1 to a script does not …

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## [Yellow Question Marks When Precompiling](https://discourse.julialang.org/t/yellow-question-marks-when-precompiling/115453)

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**Author:** [@Cyan](https://discourse.julialang.org/u/Cyan)\
**Replies:** 7\
**Last updated:** [June 13, 2024, 4:49am UTC](https://discourse.julialang.org/t/yellow-question-marks-when-precompiling/115453 "2024-06-13T04:49:20Z")

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Why there are a lot of yellow question marks show up during precompiling when I download new packages? I can using new packages normally. Perhaps someone can point me how to solve it?

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## [Documentation build and depolyment problem: - ✘ \`push\_preview\` keyword argument to deploydocs is \`true\`](https://discourse.julialang.org/t/documentation-build-and-depolyment-problem-push-preview-keyword-argument-to-deploydocs-is-true/115454)

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**Author:** [@yhuang](https://discourse.julialang.org/u/yhuang)\
**Replies:** 1\
**Last updated:** [June 13, 2024, 3:15am UTC](https://discourse.julialang.org/t/documentation-build-and-depolyment-problem-push-preview-keyword-argument-to-deploydocs-is-true/115454 "2024-06-13T03:15:06Z")

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I’m developing a package SDPLRPlus.jl and am deploying the documentation. I can compile and view the documentation locally but I have some trouble deploying it. I can see my gh-pages branch is quite different from others…

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## [Export to HTML fails](https://discourse.julialang.org/t/export-to-html-fails/115518)

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**Author:** [@bobmccrory](https://discourse.julialang.org/u/bobmccrory)\
**Replies:** 0\
**Last updated:** [June 11, 2024, 9:45pm UTC](https://discourse.julialang.org/t/export-to-html-fails/115518 "2024-06-11T21:45:28Z")

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I’m coding Jupyter notebooks in Julia in VSCode. Being an old guy, I like to print out the code and mark it up. (Pathetic, right?) When I updated Python to 3.12.4, I can no longer do this, and I get very confusing error …

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## [No legend using lines (and plots)](https://discourse.julialang.org/t/no-legend-using-lines-and-plots/115483)

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**Author:** [@NaSi](https://discourse.julialang.org/u/NaSi)\
**Replies:** 2\
**Last updated:** [June 11, 2024, 3:48pm UTC](https://discourse.julialang.org/t/no-legend-using-lines-and-plots/115483 "2024-06-11T15:48:28Z")

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Hi ! I am a new user of Julia and I have some issues to show legends on my plots : f = Figure() lines(f\[1,1\],time\_test,data\[1,:\], label=\[“Time 1”\], linewidth=3) the legend of the curve should appear, right ? Thanks, …

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## [When should one type annotate a function signature?](https://discourse.julialang.org/t/when-should-one-type-annotate-a-function-signature/115019)

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**Author:** [@Ujjwal\_Panda](https://discourse.julialang.org/u/Ujjwal_Panda)\
**Replies:** 5\
**Last updated:** [June 11, 2024, 2:13pm UTC](https://discourse.julialang.org/t/when-should-one-type-annotate-a-function-signature/115019 "2024-06-11T14:13:23Z")

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When developing a package, what is the convention when it comes to type annotating a function’s arguments? For instance, say I have a function that takes in three arguments, like so: function f(a, b, c) @. a \* b + c…

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## [Groupby on an expression or a vector?](https://discourse.julialang.org/t/groupby-on-an-expression-or-a-vector/115409)

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**Author:** [@Chriz\_Zend](https://discourse.julialang.org/u/Chriz_Zend)\
**Replies:** 21\
**Last updated:** [June 11, 2024, 2:05pm UTC](https://discourse.julialang.org/t/groupby-on-an-expression-or-a-vector/115409 "2024-06-11T14:05:43Z")

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Hello, I have the impression that is not possible… not with Julia, anyway… In Python, it’s quite easy: you can group the lines of a dataframe based on a condition (or even a random vector as long as it has the same num…

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## [Launch Failure](https://discourse.julialang.org/t/launch-failure/103694)

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**Author:** [@hanyas](https://discourse.julialang.org/u/hanyas)\
**Replies:** 10\
**Last updated:** [September 9, 2023, 11:55am UTC](https://discourse.julialang.org/t/launch-failure/103694 "2023-09-09T11:55:18Z")

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I am using an up to date arch linux distro. I’ve downloaded julia-1.6.7 from the official website and set the path. When I run julia in a console I get the following error: ┌ Warning: CHOLMOD version incompatibility │ │…

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## ["Diagonal coordinate system" for Julia arrays](https://discourse.julialang.org/t/diagonal-coordinate-system-for-julia-arrays/115447)

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**Author:** [@oOosys](https://discourse.julialang.org/u/oOosys)\
**Replies:** 15\
**Last updated:** [June 11, 2024, 9:46am UTC](https://discourse.julialang.org/t/diagonal-coordinate-system-for-julia-arrays/115447 "2024-06-11T09:46:05Z")

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I would like to be able to use a “diagonal coordinate system” to access array items the same way as with a “column/row system”. In other words I would like to access the elements using indices and slices which specify th…

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## [Batched matmul with einsum](https://discourse.julialang.org/t/batched-matmul-with-einsum/115448)

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**Author:** [@smartalecH](https://discourse.julialang.org/u/smartalecH)\
**Replies:** 1\
**Last updated:** [June 11, 2024, 12:15am UTC](https://discourse.julialang.org/t/batched-matmul-with-einsum/115448 "2024-06-11T00:15:34Z")

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I’m performing a batched matmul using Einsum. Is there a clean way to infer leading dimensions, like I can with numpy? For example, I’m currently doing this: @einsum C\[k, l, m, j\] = A\[i, j\] \* B\[k, l, m, j\] But it’d be…

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## [I cant understand the equations written in trixi](https://discourse.julialang.org/t/i-cant-understand-the-equations-written-in-trixi/115376)

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**Author:** [@Chowdhury\_MD\_Irtiza](https://discourse.julialang.org/u/Chowdhury_MD_Irtiza)\
**Replies:** 12\
**Last updated:** [June 10, 2024, 6:43pm UTC](https://discourse.julialang.org/t/i-cant-understand-the-equations-written-in-trixi/115376 "2024-06-10T18:43:29Z")

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Hello, my professor gave me a problem to solve, and in order to solve the problem, I have to modify the compressible navier-strokes equation 2D that already in trixi documentation into fully compressible reactive unstead…

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## [Density and histograms](https://discourse.julialang.org/t/density-and-histograms/115394)

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**Author:** [@LoneWolf1304](https://discourse.julialang.org/u/LoneWolf1304)\
**Replies:** 5\
**Last updated:** [June 10, 2024, 3:49pm UTC](https://discourse.julialang.org/t/density-and-histograms/115394 "2024-06-10T15:49:55Z")

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I am using Julia for plotting the density of a data using density(). I wanted to know if there is any way to obtain the data points of the density(), like the values that is plotted by density(). I can obtain the histogr…

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## [Julia PyPlot updating vector fields](https://discourse.julialang.org/t/julia-pyplot-updating-vector-fields/115431)

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**Author:** [@rzhou-space](https://discourse.julialang.org/u/rzhou-space)\
**Replies:** 0\
**Last updated:** [June 10, 2024, 2:49pm UTC](https://discourse.julialang.org/t/julia-pyplot-updating-vector-fields/115431 "2024-06-10T14:49:22Z")

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Hi all, i am new to Julia and trying to plot a dynamic vector field generated by PIV analysis. I tried to achieve by ploting the vector fields in a for loop and at each step clear the old vector field and replace it wit…

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## [Using JupyterLab](https://discourse.julialang.org/t/using-jupyterlab/20595)

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**Author:** [@yordiak](https://discourse.julialang.org/u/yordiak)\
**Replies:** 11\
**Last updated:** [June 10, 2024, 9:51am UTC](https://discourse.julialang.org/t/using-jupyterlab/20595 "2024-06-10T09:51:47Z")

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Hello, Since I am a newbie in Julia, I would appreciated if you could provide me the steps on who to make Julia to work in Jupyterlab. I am running julia 1.1.0 on win10. I use winpython as my python (v3.6) distribution…

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## [\`Base.max(::Int, ::Int) = nothing\` crashes Julia](https://discourse.julialang.org/t/base-max-int-int-nothing-crashes-julia/115396)

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**Author:** [@sadish-d](https://discourse.julialang.org/u/sadish-d)\
**Replies:** 7\
**Last updated:** [June 9, 2024, 7:48pm UTC](https://discourse.julialang.org/t/base-max-int-int-nothing-crashes-julia/115396 "2024-06-09T19:48:37Z")

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I did Base.max(::Int, ::Int) = nothing and it crashed Julia. Is this expected behavior or should it be reported?

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## [Plotting using \`Trixi2Vtk\` of \`.h5\` files](https://discourse.julialang.org/t/plotting-using-trixi2vtk-of-h5-files/115337)

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**Author:** [@Devansh1106](https://discourse.julialang.org/u/Devansh1106)\
**Replies:** 2\
**Last updated:** [June 9, 2024, 2:20pm UTC](https://discourse.julialang.org/t/plotting-using-trixi2vtk-of-h5-files/115337 "2024-06-09T14:20:30Z")

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I am plotting some .h5 solution files that are generated from running code similar to Trixi package. I am using Trixi2Vtk package for plotting. Command given in Trixi docs is: julia\> trixi2vtk(joinpath("out", "solution…

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