# New to Julia

**URL:** https://discourse.julialang.org/c/first-steps/8.md?page=17

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

**Page:** 18

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## [Solving a function = 0, where my function is approximated by a vector from a differential equation solution](https://discourse.julialang.org/t/solving-a-function-0-where-my-function-is-approximated-by-a-vector-from-a-differential-equation-solution/127811)

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**Author:** [@matyaspayn](https://discourse.julialang.org/u/matyaspayn)\
**Replies:** 4\
**Last updated:** [April 8, 2025, 7:44am UTC](https://discourse.julialang.org/t/solving-a-function-0-where-my-function-is-approximated-by-a-vector-from-a-differential-equation-solution/127811 "2025-04-08T07:44:10Z")

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Hello, This problem is quite specific and difficult to explain, but I am quite stuck so I wanted to ask to see if anyone has gotten over this problem before. I have solved a differential equation and am now analysing t…

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## [Working directory](https://discourse.julialang.org/t/working-directory/127797)

<div class="topic-metadata">

**Author:** [@Magnus\_Lilledahl](https://discourse.julialang.org/u/Magnus_Lilledahl)\
**Replies:** 4\
**Last updated:** [April 7, 2025, 7:53pm UTC](https://discourse.julialang.org/t/working-directory/127797 "2025-04-07T19:53:03Z")

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I have a package that provides some functions that needs data stored in files on the users computer My plan was to require that these files are stored in the same folder as the file that imports (using package) the pack…

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## [How to link a Selector to a column of a DataTable](https://discourse.julialang.org/t/how-to-link-a-selector-to-a-column-of-a-datatable/127723)

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**Author:** [@edmund.r](https://discourse.julialang.org/u/edmund.r)\
**Replies:** 4\
**Last updated:** [April 7, 2025, 2:01pm UTC](https://discourse.julialang.org/t/how-to-link-a-selector-to-a-column-of-a-datatable/127723 "2025-04-07T14:01:24Z")

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Hi, I have some JSON of the form j = JSON.parse("""\[{"A":"one", "B":2},{"A":"three","B":4}\]""") I have made a DataTable by dt = DataTable(DataFrame(j)) Next I would like to bind a Selector control to a column. I …

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## [How to interpret "Type{T} where T" in Julia's type system](https://discourse.julialang.org/t/how-to-interpret-type-t-where-t-in-julias-type-system/37402)

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**Author:** [@samuel](https://discourse.julialang.org/u/samuel)\
**Replies:** 22\
**Last updated:** [April 7, 2025, 6:45am UTC](https://discourse.julialang.org/t/how-to-interpret-type-t-where-t-in-julias-type-system/37402 "2025-04-07T06:45:02Z")

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I have some problems parsing the Julias type-system.. and I came up with a few questions. Docs - Types: “Type{T} is an abstract type whose only instance is the object T” How can an abstract type have instances?? As …

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## [Change x axis so 0dg points north?](https://discourse.julialang.org/t/change-x-axis-so-0dg-points-north/127733)

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**Author:** [@abletec](https://discourse.julialang.org/u/abletec)\
**Replies:** 5\
**Last updated:** [April 6, 2025, 11:06pm UTC](https://discourse.julialang.org/t/change-x-axis-so-0dg-points-north/127733 "2025-04-06T23:06:05Z")

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I’m really new to Julia but like what I see so far. My goal is to write a program to help blind folks draw. For kids, it’ll help w/spatial orientation. For everyone, it’ll help them to communicate using graphics. Likely …

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## [How are non programmers to use Julia Apps](https://discourse.julialang.org/t/how-are-non-programmers-to-use-julia-apps/127762)

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**Author:** [@TinWallop](https://discourse.julialang.org/u/TinWallop)\
**Replies:** 3\
**Last updated:** [April 6, 2025, 6:33pm UTC](https://discourse.julialang.org/t/how-are-non-programmers-to-use-julia-apps/127762 "2025-04-06T18:33:30Z")

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How are non programmers to use Apps written in Julia? I know this isn’t a new topic and I know about PackageManager etc. but I’m still confused about what Julia is for. Are you expecting people to install Julia? I migh…

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## [Brainstorming about a game engine's architecture](https://discourse.julialang.org/t/brainstorming-about-a-game-engines-architecture/127760)

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**Author:** [@Gesee](https://discourse.julialang.org/u/Gesee)\
**Replies:** 1\
**Last updated:** [April 6, 2025, 4:09pm UTC](https://discourse.julialang.org/t/brainstorming-about-a-game-engines-architecture/127760 "2025-04-06T16:09:57Z")

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Hello everyone, I have been thinking about making a game engine, so I did a little brainstorming about his architecture but since I new to Julia and programming in general (I started just 1.5 years ago as a self taught),…

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## [What is the best way to implement PINN in Julia](https://discourse.julialang.org/t/what-is-the-best-way-to-implement-pinn-in-julia/127713)

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**Author:** [@Yang-yang](https://discourse.julialang.org/u/Yang-yang)\
**Replies:** 18\
**Last updated:** [April 6, 2025, 2:37pm UTC](https://discourse.julialang.org/t/what-is-the-best-way-to-implement-pinn-in-julia/127713 "2025-04-06T14:37:28Z")

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Dear all, I want to use PINNs to solve a PDE. There are two packages in Julia that can do this NeuralPDE.jl and Sophon.jl Both of these packages use the finite difference method to realize derivatives. I want to know i…

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## [Plotly in Julia - Questions](https://discourse.julialang.org/t/plotly-in-julia-questions/127727)

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**Author:** [@Episki](https://discourse.julialang.org/u/Episki)\
**Replies:** 11\
**Last updated:** [April 6, 2025, 9:50am UTC](https://discourse.julialang.org/t/plotly-in-julia-questions/127727 "2025-04-06T09:50:34Z")

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Hi community, I’m re-starting my Julia journey since at work we have a toy project with it. I have a question regarding the use of Plotly in Julia, since it is the graphing library I mostly use in Python: What is the…

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## [Call original method when redefining a method. (Compact float printing in IJulia)](https://discourse.julialang.org/t/call-original-method-when-redefining-a-method-compact-float-printing-in-ijulia/74111)

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**Author:** [@tfiers](https://discourse.julialang.org/u/tfiers)\
**Replies:** 6\
**Last updated:** [April 6, 2025, 5:24am UTC](https://discourse.julialang.org/t/call-original-method-when-redefining-a-method-compact-float-printing-in-ijulia/74111 "2025-04-06T05:24:25Z")

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I want to print floats (and derived types such as Unitful.Quantity{Float64, …}) compactly in IJulia / the REPL. E.g. 0.1\*3 should be echoed as 0.3 and not 0.30000000000000004. Likewise, 0.1\*3mV should be 0.3 mV and not…

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## [Poor openBLAS performance for large matrix multiply?](https://discourse.julialang.org/t/poor-openblas-performance-for-large-matrix-multiply/119354)

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**Author:** [@gluon-free](https://discourse.julialang.org/u/gluon-free)\
**Replies:** 17\
**Last updated:** [April 4, 2025, 11:03am UTC](https://discourse.julialang.org/t/poor-openblas-performance-for-large-matrix-multiply/119354 "2025-04-04T11:03:02Z")

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I am new to Julia and not an experienced programmer. Playing with things and trying simple benchmarks for my new Ryzen 9950x. This one rises a question: using MKL using CUDA, LinearAlgebra, Pkg, BenchmarkTools let N = …

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## [Generator sometimes works, sometimes not](https://discourse.julialang.org/t/generator-sometimes-works-sometimes-not/127701)

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**Author:** [@WalterMadelim](https://discourse.julialang.org/u/WalterMadelim)\
**Replies:** 3\
**Last updated:** [April 4, 2025, 3:08pm UTC](https://discourse.julialang.org/t/generator-sometimes-works-sometimes-not/127701 "2025-04-04T15:08:10Z")

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It’s about Generator Expressions. I used to only know about sum(i for i in 1:I). But today I happened to discover that we can also write minimum(i for i in 1:I). I’m thus intrigued: Do all function who takes an Vect…

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## [How to stop a cell in VS Code](https://discourse.julialang.org/t/how-to-stop-a-cell-in-vs-code/80010)

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**Author:** [@chadagreene](https://discourse.julialang.org/u/chadagreene)\
**Replies:** 22\
**Last updated:** [April 4, 2025, 1:48am UTC](https://discourse.julialang.org/t/how-to-stop-a-cell-in-vs-code/80010 "2025-04-04T01:48:57Z")

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How do I stop a cell that’s running in VS Code? The Stop button does nothing at all, nor does Ctrl+C. Since I took this screenshot, the cell chugged along for another 10 minutes until I finally gave up and had to restart…

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## [Event handling with differential equation](https://discourse.julialang.org/t/event-handling-with-differential-equation/127677)

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**Author:** [@Mishal](https://discourse.julialang.org/u/Mishal)\
**Replies:** 1\
**Last updated:** [April 3, 2025, 5:16pm UTC](https://discourse.julialang.org/t/event-handling-with-differential-equation/127677 "2025-04-03T17:16:44Z")

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Hi Guys Please refer to the below code, I have included the entire code. However the “statespace” function has a bunch of if statements which alter the differential equation based on certain criteria. Is it possible to…

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## [Change of type results in totally different error](https://discourse.julialang.org/t/change-of-type-results-in-totally-different-error/127663)

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**Author:** [@adfdfdfk](https://discourse.julialang.org/u/adfdfdfk)\
**Replies:** 8\
**Last updated:** [April 3, 2025, 1:04pm UTC](https://discourse.julialang.org/t/change-of-type-results-in-totally-different-error/127663 "2025-04-03T13:04:26Z")

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Hello im new to the julia, start just a 2weeks ago im trying to write down mle fitting code with given reference code At first , usually LoadError: TypeError: in typeassert, expected Vector{Any}, got a value of type Ve…

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## [Pkg generate error](https://discourse.julialang.org/t/pkg-generate-error/127627)

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**Author:** [@Magnus\_Lilledahl](https://discourse.julialang.org/u/Magnus_Lilledahl)\
**Replies:** 4\
**Last updated:** [April 2, 2025, 3:09pm UTC](https://discourse.julialang.org/t/pkg-generate-error/127627 "2025-04-02T15:09:24Z")

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I am trying to generate a package using Pkg generate. Pkg\>generate test gave ERROR: GitError(Code:ERROR, Class:SSL, Your Julia is built with a SSL/TLS engine that libgit2 doesn't know how to configure to use a file or…

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## [How to set DateTime format of xlabel using Makie](https://discourse.julialang.org/t/how-to-set-datetime-format-of-xlabel-using-makie/127397)

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**Author:** [@dk-zen](https://discourse.julialang.org/u/dk-zen)\
**Replies:** 3\
**Last updated:** [April 2, 2025, 9:19am UTC](https://discourse.julialang.org/t/how-to-set-datetime-format-of-xlabel-using-makie/127397 "2025-04-02T09:19:21Z")

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I want to get xlabel like “HH:MM”, Part of my code as follows. It doesn’t work as I want, but without throwing out an error. Anyone can give some suggestions? fig = Figure(; size=(1000, 600)) ax1 = Axis(fig\[1, 1\], ylabe…

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## [Awkward case with multiple-dispatch and type heirachy](https://discourse.julialang.org/t/awkward-case-with-multiple-dispatch-and-type-heirachy/127606)

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**Author:** [@LEXUGE](https://discourse.julialang.org/u/LEXUGE)\
**Replies:** 5\
**Last updated:** [April 1, 2025, 9:36pm UTC](https://discourse.julialang.org/t/awkward-case-with-multiple-dispatch-and-type-heirachy/127606 "2025-04-01T21:36:23Z")

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Some disclaimer: I am still learning Julia and I think it’s natural for me to compare it with a language I am fluent in – Rust. But I am not here arguing Rust is better than Julia or vice versa. I am totally happy and o…

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## [Bifurcation problem](https://discourse.julialang.org/t/bifurcation-problem/127590)

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**Author:** [@Mkriti\_Marco](https://discourse.julialang.org/u/Mkriti_Marco)\
**Replies:** 5\
**Last updated:** [April 1, 2025, 2:43pm UTC](https://discourse.julialang.org/t/bifurcation-problem/127590 "2025-04-01T14:43:44Z")

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Hi, I have a parameter p = \[ P1 and P2\] and I compute my residual and Jacobian of my problem by varying only the P2 but passing p as the input. In Julia when I try to pass just the P2 Parameter to bifurcation problem wh…

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## [Transfering existing code to Pkg package structure](https://discourse.julialang.org/t/transfering-existing-code-to-pkg-package-structure/127594)

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**Author:** [@Magnus\_Lilledahl](https://discourse.julialang.org/u/Magnus_Lilledahl)\
**Replies:** 5\
**Last updated:** [April 1, 2025, 2:22pm UTC](https://discourse.julialang.org/t/transfering-existing-code-to-pkg-package-structure/127594 "2025-04-01T14:22:17Z")

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I have a (relatively) large Module where all the code is organized in my homegrown file and directory structure. I now want to transfer this code into the directory structure of a Pkg package (i.e project/manifest.toml, …

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## [Package versioning](https://discourse.julialang.org/t/package-versioning/127593)

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**Author:** [@Magnus\_Lilledahl](https://discourse.julialang.org/u/Magnus_Lilledahl)\
**Replies:** 3\
**Last updated:** [April 1, 2025, 2:15pm UTC](https://discourse.julialang.org/t/package-versioning/127593 "2025-04-01T14:15:41Z")

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When adding packages using Pkg one can choose version using @x.y.z syntax after the package name. Is this number tied to the version entry in the project.toml file? Is this unrelated to any versioning in git (ie tag?). I…

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## [Naming elements in a Matrix](https://discourse.julialang.org/t/naming-elements-in-a-matrix/127553)

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**Author:** [@WalterMadelim](https://discourse.julialang.org/u/WalterMadelim)\
**Replies:** 9\
**Last updated:** [April 1, 2025, 12:11pm UTC](https://discourse.julialang.org/t/naming-elements-in-a-matrix/127553 "2025-04-01T12:11:56Z")

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I find this usage interesting (see the second to last julia\>) julia\> a = (b = 1; c = 2); julia\> a, b, c (2, 1, 2) julia\> a = (d = 3, e = 4) (d = 3, e = 4) julia\> @isdefined(d) || @isdefined(e) false julia\> f = \[d=3,…

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## [How to properly implement Heatmap efficiently?](https://discourse.julialang.org/t/how-to-properly-implement-heatmap-efficiently/127582)

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**Author:** [@matyaspayn](https://discourse.julialang.org/u/matyaspayn)\
**Replies:** 9\
**Last updated:** [April 1, 2025, 11:28am UTC](https://discourse.julialang.org/t/how-to-properly-implement-heatmap-efficiently/127582 "2025-04-01T11:28:22Z")

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I am currently trying to visualise a solution to a set of differential equations, where u is my solution, and though my code works the running of the heatmap to visualise it takes at least 200 seconds each time. It shoul…

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## [Optim finite differences use a vectorized version](https://discourse.julialang.org/t/optim-finite-differences-use-a-vectorized-version/127047)

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**Author:** [@JADekker](https://discourse.julialang.org/u/JADekker)\
**Replies:** 3\
**Last updated:** [April 1, 2025, 8:08am UTC](https://discourse.julialang.org/t/optim-finite-differences-use-a-vectorized-version/127047 "2025-04-01T08:08:07Z")

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Hi, I’m in an optimization setting where I have to minimize a function f, where I have a “vector version” and a “matrix version” of the function “f” such that “calling the vector version N times” is typically slower than…

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## [Parameter fitting for a multi-domain PDE](https://discourse.julialang.org/t/parameter-fitting-for-a-multi-domain-pde/127538)

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**Author:** [@Anish\_Kumar](https://discourse.julialang.org/u/Anish_Kumar)\
**Replies:** 2\
**Last updated:** [April 1, 2025, 7:53am UTC](https://discourse.julialang.org/t/parameter-fitting-for-a-multi-domain-pde/127538 "2025-04-01T07:53:40Z")

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Hi all, I am trying to solve a system of reaction diffusion reaction equation on two different scale - one at a macro scale and one at micro scale. The micro-scale model receives conc as Dirichlet BC from the macro-scal…

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## [Facing problem writing code of heat equation](https://discourse.julialang.org/t/facing-problem-writing-code-of-heat-equation/127524)

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**Author:** [@Stayal](https://discourse.julialang.org/u/Stayal)\
**Replies:** 0\
**Last updated:** [March 30, 2025, 8:37pm UTC](https://discourse.julialang.org/t/facing-problem-writing-code-of-heat-equation/127524 "2025-03-30T20:37:19Z")

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Hello everyone I am a beginner in Gridap. I try to write heat equation code but it shows error using Gridap import Gridap: ∇ using Printf phi(x) = x\[1\]\*(1 - x\[1\]) \* x\[2\]\*(1 - x\[2\]) u\_ex(x, t) = t^2 \* phi(x) f(x, t) = …

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## [Difference between pkg REPL and julia -e 'using Pkg; Pkg.\[some command\]'?](https://discourse.julialang.org/t/difference-between-pkg-repl-and-julia-e-using-pkg-pkg-some-command/127519)

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**Author:** [@luc-spec](https://discourse.julialang.org/u/luc-spec)\
**Replies:** 6\
**Last updated:** [March 30, 2025, 7:22pm UTC](https://discourse.julialang.org/t/difference-between-pkg-repl-and-julia-e-using-pkg-pkg-some-command/127519 "2025-03-30T19:22:11Z")

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From what I understand, there are a couple of ways to install a package with Julia. the pkg REPL (julia, then the \] key, then add \[SomePkg\]) \`julia -e ‘using Pkg; Pkg.add(“\[SomePkg\]”)’ I’m working with a custom packag…

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## [Bifurcation kit](https://discourse.julialang.org/t/bifurcation-kit/127498)

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**Author:** [@mohan\_kumar](https://discourse.julialang.org/u/mohan_kumar)\
**Replies:** 1\
**Last updated:** [March 29, 2025, 11:44pm UTC](https://discourse.julialang.org/t/bifurcation-kit/127498 "2025-03-29T23:44:57Z")

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Hello everyone, I am a new user of Julia. I am currently using bifurcation kit to solve the simple circle equation such as : x^2 + y^2 = 1 and perform continuation and trace a complete circle with x as my variable and…

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## [Symbolic random variables and distributions](https://discourse.julialang.org/t/symbolic-random-variables-and-distributions/125348)

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**Author:** [@JADekker](https://discourse.julialang.org/u/JADekker)\
**Replies:** 5\
**Last updated:** [March 29, 2025, 8:31pm UTC](https://discourse.julialang.org/t/symbolic-random-variables-and-distributions/125348 "2025-03-29T20:31:31Z")

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Hi, I’m not sure how to phrase this question, so please bear with me: I’ve written a function f which takes an input x and returns a vector \[p\_1(x),...,p\_K(x)\], which correspond to the first K orthogonal polynomials cor…

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## [Adding a dimension with derived units in Unitful](https://discourse.julialang.org/t/adding-a-dimension-with-derived-units-in-unitful/127476)

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**Author:** [@mjmat](https://discourse.julialang.org/u/mjmat)\
**Replies:** 0\
**Last updated:** [March 28, 2025, 11:39pm UTC](https://discourse.julialang.org/t/adding-a-dimension-with-derived-units-in-unitful/127476 "2025-03-28T23:39:29Z")

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Hello, I am trying to add a dimension to Unitful. I can do that, and I can create (and use) a refunit, but I can’t seem to be able to create derived units. In the code below, the commented line in the module (trying to…

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