# Latest

**URL:** https://discourse.julialang.org/latest.md?page=793

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

**Page:** 794

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## [Compilation-ignoring timer?](https://discourse.julialang.org/t/compilation-ignoring-timer/93512)

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**Author:** [@BioTurboNick](https://discourse.julialang.org/u/BioTurboNick)\
**Replies:** 4\
**Last updated:** [February 3, 2023, 1:37am UTC](https://discourse.julialang.org/t/compilation-ignoring-timer/93512 "2023-02-03T01:37:54Z")

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Does Julia have, or would it be possible to add, a compilation-ignoring timer? Use case: setting a time limit for running a function, as is common for optimizers. The first execution will be necessarily longer than the …

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## [JuMP MethodError: Cannot \`convert\` an object of type AffExpr to an object of type VariableRef](https://discourse.julialang.org/t/jump-methoderror-cannot-convert-an-object-of-type-affexpr-to-an-object-of-type-variableref/93951)

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**Author:** [@Stuart\_Rogers](https://discourse.julialang.org/u/Stuart_Rogers)\
**Replies:** 2\
**Last updated:** [February 3, 2023, 1:35am UTC](https://discourse.julialang.org/t/jump-methoderror-cannot-convert-an-object-of-type-affexpr-to-an-object-of-type-variableref/93951 "2023-02-03T01:35:18Z")

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The first way of imposing the constraints works. The second way causes the error below. Is there a better way to impose theses constraints? using JuMP using LinearAlgebra v = 64 J = 10 model = Model() @variable(model, …

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## [Make a Copy of a DataFrame Row](https://discourse.julialang.org/t/make-a-copy-of-a-dataframe-row/93953)

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**Author:** [@quietlight](https://discourse.julialang.org/u/quietlight)\
**Replies:** 9\
**Last updated:** [February 2, 2023, 11:34pm UTC](https://discourse.julialang.org/t/make-a-copy-of-a-dataframe-row/93953 "2023-02-02T23:34:03Z")

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I am stuck on this for loop. I need a copy of a dataframe row so I can modify it and then push the modified row onto to the dataframe. My K-MF label means a male and female kiwi are both calling at the same time, I want…

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## [Doc string for overloaded Base method?](https://discourse.julialang.org/t/doc-string-for-overloaded-base-method/93957)

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**Author:** [@greatpet](https://discourse.julialang.org/u/greatpet)\
**Replies:** 1\
**Last updated:** [February 2, 2023, 11:30pm UTC](https://discourse.julialang.org/t/doc-string-for-overloaded-base-method/93957 "2023-02-02T23:30:23Z")

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If I overload e.g. Base.getindex() for my custom type, how do I include a doc string that gets automatically displayed by Documenter.jl for documenting my package? Documenter.jl seems to use the “original” doc string inc…

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## [Generating derived variables from ModelingToolkit.jl - variable of interest eliminated during structural\_simplify](https://discourse.julialang.org/t/generating-derived-variables-from-modelingtoolkit-jl-variable-of-interest-eliminated-during-structural-simplify/93939)

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**Author:** [@sdwfrost](https://discourse.julialang.org/u/sdwfrost)\
**Replies:** 8\
**Last updated:** [February 2, 2023, 10:56pm UTC](https://discourse.julialang.org/t/generating-derived-variables-from-modelingtoolkit-jl-variable-of-interest-eliminated-during-structural-simplify/93939 "2023-02-02T22:56:04Z")

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Hi everyone, I’m trying to generate variables that are functions of my state variables in an ODE. Here’s my example. using ModelingToolkit using OrdinaryDiffEq @parameters t β c γ @variables S(t) I(t) R(t) λ(t) D = Di…

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## [Delete all variables - Pluto notebook - Julia](https://discourse.julialang.org/t/delete-all-variables-pluto-notebook-julia/93245)

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**Author:** [@Students](https://discourse.julialang.org/u/Students)\
**Replies:** 6\
**Last updated:** [January 22, 2023, 3:03am UTC](https://discourse.julialang.org/t/delete-all-variables-pluto-notebook-julia/93245 "2023-01-22T03:03:31Z")

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Hello, I want to clear all the variables defined before by running a cell in pluto notebook. I am new here! Thanks for the help Thank you!

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## [Edit an externally hosted standard library](https://discourse.julialang.org/t/edit-an-externally-hosted-standard-library/90740)

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**Author:** [@Lilith](https://discourse.julialang.org/u/Lilith)\
**Replies:** 4\
**Last updated:** [February 2, 2023, 9:12pm UTC](https://discourse.julialang.org/t/edit-an-externally-hosted-standard-library/90740 "2023-02-02T21:12:12Z")

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Most packages can be edited with \]dev DataFrames. Code in Julia’s Base and internal stdlibs (those hosted in GitHub - JuliaLang/julia: The Julia Programming Language) can be edited by cloning Julia and using Revise.track…

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## [min(NaN,5) = NaN (why no @fastmath?)](https://discourse.julialang.org/t/min-nan-5-nan-why-no-fastmath/93736)

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**Author:** [@Marcell\_Havlik](https://discourse.julialang.org/u/Marcell_Havlik)\
**Replies:** 47\
**Last updated:** [February 2, 2023, 9:03pm UTC](https://discourse.julialang.org/t/min-nan-5-nan-why-no-fastmath/93736 "2023-02-02T21:03:44Z")

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Hey Julianners, I just want to ask, as I ran into this problem 4th times even after that I know what causes this problem. Shouldn’t we make it happen to be correct as it is expected like in other languages? So basic…

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## [\[ANN\] ChoosyDataLoggers.jl: choosy practices for logging data in numerical experiments](https://discourse.julialang.org/t/ann-choosydataloggers-jl-choosy-practices-for-logging-data-in-numerical-experiments/93419)

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**Author:** [@mkschleg](https://discourse.julialang.org/u/mkschleg)\
**Replies:** 4\
**Last updated:** [February 2, 2023, 8:53pm UTC](https://discourse.julialang.org/t/ann-choosydataloggers-jl-choosy-practices-for-logging-data-in-numerical-experiments/93419 "2023-02-02T20:53:15Z")

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Hello! I think many people may find a use in the package ChoosyDataLoggers.jl, especially those running Reinforcement Learning or Machine Learning experiments. The ChoosyDataLoggers package is used to log various groups…

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## [Solution of 3d linear system](https://discourse.julialang.org/t/solution-of-3d-linear-system/93931)

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**Author:** [@jcbritobr](https://discourse.julialang.org/u/jcbritobr)\
**Replies:** 15\
**Last updated:** [February 2, 2023, 8:52pm UTC](https://discourse.julialang.org/t/solution-of-3d-linear-system/93931 "2023-02-02T20:52:49Z")

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Hello, good morning. Im trying to solve this 3d system, that will plot a plane in surface. I have a matlab book and I’m porting some exercises. The solution is a line between the two planes as the book shows: In m…

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## [Add personalized column for "time intervals"](https://discourse.julialang.org/t/add-personalized-column-for-time-intervals/93938)

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**Author:** [@Matilopez06](https://discourse.julialang.org/u/Matilopez06)\
**Replies:** 12\
**Last updated:** [February 2, 2023, 8:11pm UTC](https://discourse.julialang.org/t/add-personalized-column-for-time-intervals/93938 "2023-02-02T20:11:28Z")

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Hello! Im working writing CSV of a diferents datas in columns in julia. I want to add to this csv file a new colum named “measure\_time” for time intervals personalized by the user for each row. For example, my data has 1…

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## [Solving systems of partial differential equations](https://discourse.julialang.org/t/solving-systems-of-partial-differential-equations/93947)

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**Author:** [@bombadil224](https://discourse.julialang.org/u/bombadil224)\
**Replies:** 0\
**Last updated:** [February 2, 2023, 7:18pm UTC](https://discourse.julialang.org/t/solving-systems-of-partial-differential-equations/93947 "2023-02-02T19:18:35Z")

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I have been trying to find a way for a while now to simulate a few different systems of PDEs. What I need to be able to do is change both the initial conditions and the system of equations, without having to go through a…

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## [What is wrong with this system of ODEs?](https://discourse.julialang.org/t/what-is-wrong-with-this-system-of-odes/93924)

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**Author:** [@Ali\_Vahdati](https://discourse.julialang.org/u/Ali_Vahdati)\
**Replies:** 2\
**Last updated:** [February 2, 2023, 7:12pm UTC](https://discourse.julialang.org/t/what-is-wrong-with-this-system-of-odes/93924 "2023-02-02T19:12:14Z")

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I have a system with 5 linear ODEs. The code runs and the results are just what I expect. In a second system, I expand the first system by duplicating the five equations. There are now 10 equations where there is no conn…

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## [NASA internships : Next-generation tools for Earth Observing analytics in Julia](https://discourse.julialang.org/t/nasa-internships-next-generation-tools-for-earth-observing-analytics-in-julia/90134)

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**Author:** [@alex-s-gardner](https://discourse.julialang.org/u/alex-s-gardner)\
**Replies:** 7\
**Last updated:** [February 2, 2023, 6:04pm UTC](https://discourse.julialang.org/t/nasa-internships-next-generation-tools-for-earth-observing-analytics-in-julia/90134 "2023-02-02T18:04:12Z")

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We (NASA/JPL) have postings up looking for interns with strong julia programming skills and knowledge of geospatial data. We need all the help we can get. APPLY HERE and search for AO #13939: Next-generation tools for E…

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## [Possible bug?](https://discourse.julialang.org/t/possible-bug/93668)

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**Author:** [@x13420x](https://discourse.julialang.org/u/x13420x)\
**Replies:** 12\
**Last updated:** [February 2, 2023, 6:33pm UTC](https://discourse.julialang.org/t/possible-bug/93668 "2023-02-02T18:33:24Z")

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using Base global primel = \[\] println(primel) println(div(10,3)) if true println(primel) println(div(10,3)) if true println(primel) println(div(10,3)) if true println(primel) println(div(10,…

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## [UndefVarError: writeshortest not defined with JSON3](https://discourse.julialang.org/t/undefvarerror-writeshortest-not-defined-with-json3/93893)

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**Author:** [@Davidfloor](https://discourse.julialang.org/u/Davidfloor)\
**Replies:** 4\
**Last updated:** [February 2, 2023, 6:23pm UTC](https://discourse.julialang.org/t/undefvarerror-writeshortest-not-defined-with-json3/93893 "2023-02-02T18:23:01Z")

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Hi, I use below code to write json file but it shows UndefVarError: writeshortest not defined. Please help me solve this problem! Thank you! h5open(solution, "r") do f t = open\_dataset(f, "t")\[:\] v = open\_datas…

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## [Why don't \`Any\` constraints check that the parameter is a type](https://discourse.julialang.org/t/why-dont-any-constraints-check-that-the-parameter-is-a-type/93920)

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**Author:** [@nsajko](https://discourse.julialang.org/u/nsajko)\
**Replies:** 12\
**Last updated:** [February 2, 2023, 6:22pm UTC](https://discourse.julialang.org/t/why-dont-any-constraints-check-that-the-parameter-is-a-type/93920 "2023-02-02T18:22:58Z")

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Why is a \<:Any constraint equivalent to there being no constraint? For abstract types: julia\> abstract type A{T \<: Any} end julia\> A{2} # Succeeds even though 2 doesn't subtype Any A{2} For concrete types: julia\> s…

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## [Interactive Menu with AlgebraOfGraphics / GLMakie](https://discourse.julialang.org/t/interactive-menu-with-algebraofgraphics-glmakie/93842)

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**Author:** [@mreichMPI-BGC](https://discourse.julialang.org/u/mreichMPI-BGC)\
**Replies:** 15\
**Last updated:** [February 2, 2023, 5:53pm UTC](https://discourse.julialang.org/t/interactive-menu-with-algebraofgraphics-glmakie/93842 "2023-02-02T17:53:46Z")

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Hello, I am trying to have an interactive AlgebraofGraphics plot, e.g. with a menu to select which variable is plotted. A MWE is x1=rand(50) y1=10x1.^2 y2=x1 .+ randn(50) df = DataFrame((;x1, y1, y2)) var=Observable(…

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## [Elegant way to handle multiple input flux layers?](https://discourse.julialang.org/t/elegant-way-to-handle-multiple-input-flux-layers/93913)

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**Author:** [@reachtarunhere](https://discourse.julialang.org/u/reachtarunhere)\
**Replies:** 4\
**Last updated:** [February 2, 2023, 5:50pm UTC](https://discourse.julialang.org/t/elegant-way-to-handle-multiple-input-flux-layers/93913 "2023-02-02T17:50:47Z")

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The issue I am pointing at arrives when implementing encoder for transformer models with masking. Below I have tried to do a fake minimal example instead. We have a custom layer which takes a couple of inputs. For a tra…

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## [Why the Loss function does not decrease significantly in Flux.jl](https://discourse.julialang.org/t/why-the-loss-function-does-not-decrease-significantly-in-flux-jl/93918)

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**Author:** [@quantiota](https://discourse.julialang.org/u/quantiota)\
**Replies:** 2\
**Last updated:** [February 2, 2023, 4:50pm UTC](https://discourse.julialang.org/t/why-the-loss-function-does-not-decrease-significantly-in-flux-jl/93918 "2023-02-02T16:50:00Z")

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After trying some optimizations on activation function and epochs value , it is not possible to fit the model to y data which is a function of the input data. using Flux, Plots, Statistics x = Array{Float64}(rand(5, 100…

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## [Qhull.jl personalisation](https://discourse.julialang.org/t/qhull-jl-personalisation/92805)

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**Author:** [@jeffzwe](https://discourse.julialang.org/u/jeffzwe)\
**Replies:** 0\
**Last updated:** [January 11, 2023, 12:40pm UTC](https://discourse.julialang.org/t/qhull-jl-personalisation/92805 "2023-01-11T12:40:49Z")

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Hi there! I’m using QHull.jl for a project where I need to calculate the volume of convex hulls in 8-d. I’m starting out with about 10 points and then iteratively adding more and more points to be included in the convex…

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## [Distribution of sum of random variables](https://discourse.julialang.org/t/distribution-of-sum-of-random-variables/69023)

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**Author:** [@alexdmeyer](https://discourse.julialang.org/u/alexdmeyer)\
**Replies:** 18\
**Last updated:** [February 2, 2023, 3:06pm UTC](https://discourse.julialang.org/t/distribution-of-sum-of-random-variables/69023 "2023-02-02T15:06:35Z")

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Hey Julia folks, An equation I came across in my research requires evaluating the distribution of a linear combination of two random variables, aX + bY. Does the Distributions.jl package have a nice way to do this? More…

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## [How could I create map with colored countries?](https://discourse.julialang.org/t/how-could-i-create-map-with-colored-countries/75634)

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**Author:** [@maajdl](https://discourse.julialang.org/u/maajdl)\
**Replies:** 5\
**Last updated:** [February 2, 2023, 3:01pm UTC](https://discourse.julialang.org/t/how-could-i-create-map-with-colored-countries/75634 "2023-02-02T15:01:04Z")

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Hello Below is the kind of maps I would like to draw. The colors would be changing according to some data. I would dream of making animated gif files on this basis. Any idea how I coul proceed? Thanks Michel

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## [Visualizing and understanding Fourier transforms](https://discourse.julialang.org/t/visualizing-and-understanding-fourier-transforms/93898)

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**Author:** [@skittishdev](https://discourse.julialang.org/u/skittishdev)\
**Replies:** 4\
**Last updated:** [February 2, 2023, 2:07pm UTC](https://discourse.julialang.org/t/visualizing-and-understanding-fourier-transforms/93898 "2023-02-02T14:07:38Z")

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Hi, I am trying to understand Fourier transforms, and decided to create some plots using Julia to help validate my own understanding. What I want Create a known signal as a sum/product of 2 other simple sinusoidal si…

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## [How to improve the calculation speed of this kernel on GPU?](https://discourse.julialang.org/t/how-to-improve-the-calculation-speed-of-this-kernel-on-gpu/93831)

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**Author:** [@Ahmed\_Salih](https://discourse.julialang.org/u/Ahmed_Salih)\
**Replies:** 2\
**Last updated:** [February 2, 2023, 1:10pm UTC](https://discourse.julialang.org/t/how-to-improve-the-calculation-speed-of-this-kernel-on-gpu/93831 "2023-02-02T13:10:26Z")

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Hello everyone! I have worked quite a bit on setting up a robust foundation for structuring my code and computation loop, with quite a few good pointers from you guys on the forum, so I hope to be able to learn more fro…

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## [What does \`\<:\` as a type parameter mean?](https://discourse.julialang.org/t/what-does-as-a-type-parameter-mean/93916)

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**Author:** [@jishnub](https://discourse.julialang.org/u/jishnub)\
**Replies:** 3\
**Last updated:** [February 2, 2023, 12:52pm UTC](https://discourse.julialang.org/t/what-does-as-a-type-parameter-mean/93916 "2023-02-02T12:52:35Z")

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julia\> Array{\<:,2} Matrix{\<:} (alias for Array{\<:, 2}) julia\> Array{\<:,2} === Array{\<:Any,2} false julia\> Matrix{\<:} isa UnionAll false I wonder if Matrix{\<:} means anything?

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## [GridapGmsh error loading .msh file when line and surface elements are used](https://discourse.julialang.org/t/gridapgmsh-error-loading-msh-file-when-line-and-surface-elements-are-used/93922)

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**Author:** [@jav](https://discourse.julialang.org/u/jav)\
**Replies:** 0\
**Last updated:** [February 2, 2023, 12:44pm UTC](https://discourse.julialang.org/t/gridapgmsh-error-loading-msh-file-when-line-and-surface-elements-are-used/93922 "2023-02-02T12:44:09Z")

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Hello all, for a task, one model contains shells (surface elements) and beams (line elements). The goal was to get a simple working model. Please see the picture: If this is loaded with GridapGmsh an error message o…

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## [AdaptiveMCMC defining prior and multivariate parameters](https://discourse.julialang.org/t/adaptivemcmc-defining-prior-and-multivariate-parameters/93917)

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**Author:** [@astro-kevin](https://discourse.julialang.org/u/astro-kevin)\
**Replies:** 0\
**Last updated:** [February 2, 2023, 11:46am UTC](https://discourse.julialang.org/t/adaptivemcmc-defining-prior-and-multivariate-parameters/93917 "2023-02-02T11:46:11Z")

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I’m trying to make a start on making a MCMC chain using AdaptiveMCMC. I’ve figured out a function which returns a log-likelihood given a specific set of parameters (a vector of parameters). I’m not quite sure how this go…

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## [JuliaFormatter: multi-line matrix in VSCode](https://discourse.julialang.org/t/juliaformatter-multi-line-matrix-in-vscode/93872)

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**Author:** [@lmiq](https://discourse.julialang.org/u/lmiq)\
**Replies:** 7\
**Last updated:** [February 2, 2023, 11:38am UTC](https://discourse.julialang.org/t/juliaformatter-multi-line-matrix-in-vscode/93872 "2023-02-02T11:38:10Z")

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In VSCode, when I use the formatter on something like this: m = \[ 1 0 0 1 \] I get something like this: m = \[ 1 0 0 1 \] Is there some option or simple way to disable that formatting of multi-line matrices?

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## [Pmap equivalent for broadcast](https://discourse.julialang.org/t/pmap-equivalent-for-broadcast/93865)

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**Author:** [@ditfurth](https://discourse.julialang.org/u/ditfurth)\
**Replies:** 7\
**Last updated:** [February 2, 2023, 10:58am UTC](https://discourse.julialang.org/t/pmap-equivalent-for-broadcast/93865 "2023-02-02T10:58:47Z")

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Hi all, I am wrangling with the following problem. I have a function, call it f, that I want to apply on each element of a vector, and that takes many References(DataFrame, matrices, scalars). In order to do it withou…

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