# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1325

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

**Page:** 1326

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## [Non-linear expressions in optimization](https://discourse.julialang.org/t/non-linear-expressions-in-optimization/64969)

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**Author:** [@Daniel\_Villamar](https://discourse.julialang.org/u/Daniel_Villamar)\
**Replies:** 5\
**Last updated:** [July 20, 2021, 4:33pm UTC](https://discourse.julialang.org/t/non-linear-expressions-in-optimization/64969 "2021-07-20T16:33:51Z")

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Hi! I use the version JuMP v0.21.4 and Julia v1.4.2 and I optimizing with Ipopt I ve been working in a non-linear optimization model. Sorry for not presenting a MWE but my code is full of things. I have a problems wit…

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## [How to input files as command line arguments to compiled Julia](https://discourse.julialang.org/t/how-to-input-files-as-command-line-arguments-to-compiled-julia/64633)

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**Author:** [@connormeaton](https://discourse.julialang.org/u/connormeaton)\
**Replies:** 46\
**Last updated:** [July 20, 2021, 3:50pm UTC](https://discourse.julialang.org/t/how-to-input-files-as-command-line-arguments-to-compiled-julia/64633 "2021-07-20T15:50:24Z")

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I am building a shippable app with Julia using the PackageCompiler.jl library. I have followed the example they provided and replicated it properly. I am now trying to modify the code piece by piece to replace the to…

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## [PDE heat equation](https://discourse.julialang.org/t/pde-heat-equation/64428)

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**Author:** [@raman\_kumar](https://discourse.julialang.org/u/raman_kumar)\
**Replies:** 24\
**Last updated:** [July 20, 2021, 3:15pm UTC](https://discourse.julialang.org/t/pde-heat-equation/64428 "2021-07-20T15:15:00Z")

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i want to solve the matrix ,but i can’t do it. i am new to Julia. please help me in finding error .i have to plot the last equation given in picture below. what is MethodError i am making?

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## [How can I speed up my Neural ODE?](https://discourse.julialang.org/t/how-can-i-speed-up-my-neural-ode/64848)

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**Author:** [@Antonino\_Gandolfo](https://discourse.julialang.org/u/Antonino_Gandolfo)\
**Replies:** 4\
**Last updated:** [July 20, 2021, 3:14pm UTC](https://discourse.julialang.org/t/how-can-i-speed-up-my-neural-ode/64848 "2021-07-20T15:14:12Z")

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Hi @ChrisRackauckas , I would like to ask you how can I speed up my code. I tried to do a system identification about an HVAC system. Here’s the code: using CSV,DataFrames,DifferentialEquations,Plots,Flux,DiffEqFlux,…

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## [Empty container reduce error: diff eq](https://discourse.julialang.org/t/empty-container-reduce-error-diff-eq/64956)

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**Author:** [@graham](https://discourse.julialang.org/u/graham)\
**Replies:** 10\
**Last updated:** [July 20, 2021, 2:52pm UTC](https://discourse.julialang.org/t/empty-container-reduce-error-diff-eq/64956 "2021-07-20T14:52:17Z")

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Hi all, I’m trying to use the DifferentialEquations.jl package to perform explicit integration of a mass-spring-damper system. Here are the function I’m solving, and how I passed it into the SecondOrderODEProblem() fun…

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## [Performance issues JuMP, GLPK](https://discourse.julialang.org/t/performance-issues-jump-glpk/64971)

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**Author:** [@Annette\_F](https://discourse.julialang.org/u/Annette_F)\
**Replies:** 4\
**Last updated:** [July 20, 2021, 1:20pm UTC](https://discourse.julialang.org/t/performance-issues-jump-glpk/64971 "2021-07-20T13:20:12Z")

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Goodmorning, I have created the following MIP which I assumed is small and would only take seconds to built and solve. I’ve been working with CPLEX/Gurobi quite a lot, just not in combination with Julia, so I expected …

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## [What is the best way to get orthogonal polynomials for a regression like R's poly function](https://discourse.julialang.org/t/what-is-the-best-way-to-get-orthogonal-polynomials-for-a-regression-like-rs-poly-function/64972)

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**Author:** [@andrewjessop](https://discourse.julialang.org/u/andrewjessop)\
**Replies:** 1\
**Last updated:** [July 20, 2021, 11:51am UTC](https://discourse.julialang.org/t/what-is-the-best-way-to-get-orthogonal-polynomials-for-a-regression-like-rs-poly-function/64972 "2021-07-20T11:51:59Z")

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R has a very easy-to-use function where you provide a vector and it will return orthogonal polynomial vectors that can be used in linear models. There are a few different polynomial packages available. Can this be done …

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## [Issue while using dictionary in Julia](https://discourse.julialang.org/t/issue-while-using-dictionary-in-julia/64925)

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**Author:** [@manoj.centura](https://discourse.julialang.org/u/manoj.centura)\
**Replies:** 4\
**Last updated:** [July 20, 2021, 10:57am UTC](https://discourse.julialang.org/t/issue-while-using-dictionary-in-julia/64925 "2021-07-20T10:57:22Z")

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items = Dict{String,Int64} Total\_craneMovement =985 MaxCraneMovement =312 CraneIntensity =Total\_craneMovement/MaxCraneMovement push!(items,"Total\_craneMovement"=\>Total\_craneMovement) push!(items,"MaxCraneMovement"=\>MaxC…

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## [Display full error message, and continue](https://discourse.julialang.org/t/display-full-error-message-and-continue/64747)

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**Author:** [@Philippe\_Maincon1](https://discourse.julialang.org/u/Philippe_Maincon1)\
**Replies:** 3\
**Last updated:** [July 20, 2021, 9:03am UTC](https://discourse.julialang.org/t/display-full-error-message-and-continue/64747 "2021-07-20T09:03:04Z")

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I want to catch an error, display the full error message, and then continue execution (to return whatever data was produced before the error. So I code (MWE) v = Vector{Vector{Float64}}(undef,3) try v\[2\] catch err …

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## [Base for Affine Geometry models](https://discourse.julialang.org/t/base-for-affine-geometry-models/64614)

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**Author:** [@Gilles\_Dubois](https://discourse.julialang.org/u/Gilles_Dubois)\
**Replies:** 22\
**Last updated:** [July 20, 2021, 7:57am UTC](https://discourse.julialang.org/t/base-for-affine-geometry-models/64614 "2021-07-20T07:57:25Z")

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Hi everybody ! This follows the previous discussion “Is Julia lazy” about models of vector spaces for educational purposes. Many propositions, suggestions have been made, all of them interesting, a lot of links too. I c…

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## [Why isn't minmax branchless?](https://discourse.julialang.org/t/why-isnt-minmax-branchless/64854)

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**Author:** [@Luapulu](https://discourse.julialang.org/u/Luapulu)\
**Replies:** 22\
**Last updated:** [July 20, 2021, 5:59am UTC](https://discourse.julialang.org/t/why-isnt-minmax-branchless/64854 "2021-07-20T05:59:19Z")

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minmax for two numbers is defined by My question is: why not make it branchless with minmax(x, y) = ifelse(isless(x, y), (x, y), (y, x))

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## [Tkinter - Error on button-click](https://discourse.julialang.org/t/tkinter-error-on-button-click/64740)

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**Author:** [@trilobit](https://discourse.julialang.org/u/trilobit)\
**Replies:** 2\
**Last updated:** [July 20, 2021, 5:29am UTC](https://discourse.julialang.org/t/tkinter-error-on-button-click/64740 "2021-07-20T05:29:04Z")

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Hi, I’m playing around with Tkinter and don’t understand why I get an error, when I want to replace a text. The test program should start a new measurement, but something goes wrong, when the “Repeat”-Button is click…

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## [Fixing parameter values when solving inverse problem using DiffEqFlux](https://discourse.julialang.org/t/fixing-parameter-values-when-solving-inverse-problem-using-diffeqflux/64963)

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**Author:** [@juliascrub](https://discourse.julialang.org/u/juliascrub)\
**Replies:** 1\
**Last updated:** [July 20, 2021, 4:27am UTC](https://discourse.julialang.org/t/fixing-parameter-values-when-solving-inverse-problem-using-diffeqflux/64963 "2021-07-20T04:27:12Z")

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Is there a way to fix certain parameters when using sciml\_train? I could manually override them in the loss function like below but am curious if theres a better way function loss(p) overridden\_p = p but with some p…

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## [Unpredictable learning of neural network based controller for dc motor](https://discourse.julialang.org/t/unpredictable-learning-of-neural-network-based-controller-for-dc-motor/64960)

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**Author:** [@shafeeq\_Elanattil](https://discourse.julialang.org/u/shafeeq_Elanattil)\
**Replies:** 2\
**Last updated:** [July 20, 2021, 4:22am UTC](https://discourse.julialang.org/t/unpredictable-learning-of-neural-network-based-controller-for-dc-motor/64960 "2021-07-20T04:22:14Z")

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Hello, I am new to the Julia language. I am trying to make neural network based position controller using Julia libraries. My code is given below. J = 0.1999 Ke = 2.1918 Kt = 38.185 L = 0.020453 R = 3.9694 Tq = 0.20142…

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## [How do I create a first examples subset of a dataframe?](https://discourse.julialang.org/t/how-do-i-create-a-first-examples-subset-of-a-dataframe/64957)

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**Author:** [@banksiaboy](https://discourse.julialang.org/u/banksiaboy)\
**Replies:** 1\
**Last updated:** [July 20, 2021, 4:16am UTC](https://discourse.julialang.org/t/how-do-i-create-a-first-examples-subset-of-a-dataframe/64957 "2021-07-20T04:16:13Z")

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I have a DataFrame with columns \[:species :jpg\_url\]. There can be many jpegs associated with each species. How do I get a subset of my DataFrame with the same columns and just the first picture associated with each spe…

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## [Warning: Package SoilWater\_ToolBox does not have Configurations in its dependencies:](https://discourse.julialang.org/t/warning-package-soilwater-toolbox-does-not-have-configurations-in-its-dependencies/64476)

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**Author:** [@JosephPollacco](https://discourse.julialang.org/u/JosephPollacco)\
**Replies:** 8\
**Last updated:** [July 20, 2021, 3:13am UTC](https://discourse.julialang.org/t/warning-package-soilwater-toolbox-does-not-have-configurations-in-its-dependencies/64476 "2021-07-20T03:13:49Z")

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Halllo, I am creating my first Package which is exciting but also challenging of the large software SoilWater-ToolBox I believe that the package works locally, but I am getting the following warning Package SoilWater\_…

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## [Local scope rules are confusing in inner scopes (Julia 1.6)](https://discourse.julialang.org/t/local-scope-rules-are-confusing-in-inner-scopes-julia-1-6/64936)

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**Author:** [@wsshin](https://discourse.julialang.org/u/wsshin)\
**Replies:** 1\
**Last updated:** [July 20, 2021, 2:03am UTC](https://discourse.julialang.org/t/local-scope-rules-are-confusing-in-inner-scopes-julia-1-6/64936 "2021-07-20T02:03:52Z")

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I am using Julia 1.6.1: julia\> VERSION v"1.6.1-pre.1" I find the local scope rules are confusing to apply to inner scopes (such as inner functions). The rules are described at described at Scope of Variables · The Ju…

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## [How to define an infix operator that can act on multiple arguments at once like \`:\`?](https://discourse.julialang.org/t/how-to-define-an-infix-operator-that-can-act-on-multiple-arguments-at-once-like/64954)

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**Author:** [@singularitti](https://discourse.julialang.org/u/singularitti)\
**Replies:** 3\
**Last updated:** [July 19, 2021, 11:21pm UTC](https://discourse.julialang.org/t/how-to-define-an-infix-operator-that-can-act-on-multiple-arguments-at-once-like/64954 "2021-07-19T23:21:53Z")

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Forgive me if I am wrong, but why can : act on 3 arguments at a time as an infix operator? julia\> @which 1:2:3 (::Colon)(start::T, step::T, stop::T) where T\<:Real in Base at range.jl:22 If I want to define a new operat…

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## [How do I use Plots with MPIClusterManagers in "only workers" mode?](https://discourse.julialang.org/t/how-do-i-use-plots-with-mpiclustermanagers-in-only-workers-mode/64286)

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**Author:** [@giancarloantonucci](https://discourse.julialang.org/u/giancarloantonucci)\
**Replies:** 2\
**Last updated:** [July 19, 2021, 10:30pm UTC](https://discourse.julialang.org/t/how-do-i-use-plots-with-mpiclustermanagers-in-only-workers-mode/64286 "2021-07-19T22:30:12Z")

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I find that @mpi\_do from MPIClusterManagers.jl is great with Jupiter notebooks. However, I’m not able to plot anything from within @mpi\_do: using MPIClusterManagers using Distributed manager = MPIManager(np = 4) addproc…

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## [Raw string "$"](https://discourse.julialang.org/t/raw-string/64948)

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**Author:** [@Angie\_Cruz](https://discourse.julialang.org/u/Angie_Cruz)\
**Replies:** 5\
**Last updated:** [July 19, 2021, 10:05pm UTC](https://discourse.julialang.org/t/raw-string/64948 "2021-07-19T22:05:58Z")

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Hello, I would like to print “abc$def” as a string x = "abc$def" but it doesn’t allow me because of the $, I tried to write it like this x="abc"\*raw"$"\*"def" but I get the following: "abc\\$def" My issue is that I d…

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## [Solving non-linear equations with anonymous function](https://discourse.julialang.org/t/solving-non-linear-equations-with-anonymous-function/64934)

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**Author:** [@bozgulec](https://discourse.julialang.org/u/bozgulec)\
**Replies:** 1\
**Last updated:** [July 19, 2021, 9:17pm UTC](https://discourse.julialang.org/t/solving-non-linear-equations-with-anonymous-function/64934 "2021-07-19T21:17:58Z")

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Hello Dear Julians, I’m currently translating a code from MATLAB to Julia and I got stuck at reformulating a non-linear differential equation problem. The code in MATLAB is as follows, for i = 1:numel(rrangeopt) r = …

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## [Need help learning Julia (tutorial example doesn't work for SQLite.Query](https://discourse.julialang.org/t/need-help-learning-julia-tutorial-example-doesnt-work-for-sqlite-query/64942)

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**Author:** [@ChaoticSun](https://discourse.julialang.org/u/ChaoticSun)\
**Replies:** 3\
**Last updated:** [July 19, 2021, 9:01pm UTC](https://discourse.julialang.org/t/need-help-learning-julia-tutorial-example-doesnt-work-for-sqlite-query/64942 "2021-07-19T21:01:04Z")

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Good afternoon. I’m trying to learn Julia and found a long tutorial (over 4 hours). I’ve been tracking along pretty well until I hit the database section using the SQLite package. I’ve created the DB (a very simple one e…

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## [How to generate Project.toml and Manifest.toml for a repository for be executed with Binder](https://discourse.julialang.org/t/how-to-generate-project-toml-and-manifest-toml-for-a-repository-for-be-executed-with-binder/64939)

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**Author:** [@empet](https://discourse.julialang.org/u/empet)\
**Replies:** 3\
**Last updated:** [July 19, 2021, 8:15pm UTC](https://discourse.julialang.org/t/how-to-generate-project-toml-and-manifest-toml-for-a-repository-for-be-executed-with-binder/64939 "2021-07-19T20:15:11Z")

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I have a local folder that contains a subfolder with two jl files, and a few Jupyter Notebooks in the root. I intend to push it to a github repository to use Binder for running the notebooks. My notebooks are using a f…

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## [Share a Jupyter or Pluto notebook](https://discourse.julialang.org/t/share-a-jupyter-or-pluto-notebook/64298)

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**Author:** [@Leonardo\_Rivera](https://discourse.julialang.org/u/Leonardo_Rivera)\
**Replies:** 5\
**Last updated:** [July 19, 2021, 6:58pm UTC](https://discourse.julialang.org/t/share-a-jupyter-or-pluto-notebook/64298 "2021-07-19T18:58:31Z")

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Hello, everyone. I want to prepare a tutorial/workshop to share my linear programming models in JuMP with some colleagues. For what I’ve read, using Jupyter notebooks, creating a repository in GitHub with the files, and …

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## [ZygoteRules dispatch on traits?](https://discourse.julialang.org/t/zygoterules-dispatch-on-traits/64869)

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**Author:** [@lamorton](https://discourse.julialang.org/u/lamorton)\
**Replies:** 2\
**Last updated:** [July 19, 2021, 5:52pm UTC](https://discourse.julialang.org/t/zygoterules-dispatch-on-traits/64869 "2021-07-19T17:52:05Z")

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Is it possible to specialize a ZygoteRule using a Holy trait? I’m not sure how I would go about doing this.

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## [Cond() error: LinearAlgebra and BigFloats incompatible?](https://discourse.julialang.org/t/cond-error-linearalgebra-and-bigfloats-incompatible/64924)

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**Author:** [@damonturney](https://discourse.julialang.org/u/damonturney)\
**Replies:** 3\
**Last updated:** [July 19, 2021, 5:46pm UTC](https://discourse.julialang.org/t/cond-error-linearalgebra-and-bigfloats-incompatible/64924 "2021-07-19T17:46:57Z")

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In the course of building my simulation of chemicals in an operating battery, I need to invert matrices that are ill-conditioned (condition number near 1E15). My strategy was to use a matrix of BigFloats because they ca…

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## [Running For loops on GPU](https://discourse.julialang.org/t/running-for-loops-on-gpu/1553)

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**Author:** [@deepakagrawal](https://discourse.julialang.org/u/deepakagrawal)\
**Replies:** 11\
**Last updated:** [July 19, 2021, 5:39pm UTC](https://discourse.julialang.org/t/running-for-loops-on-gpu/1553 "2021-07-19T17:39:41Z")

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I am trying to do simulation in which I am repeating same function multiple times Changing several parameters Is there a way I can do any of them via a for loop or some other way on GPU? I am new to Julia. Any help o…

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## [Treemap subplot in PlotlyJS](https://discourse.julialang.org/t/treemap-subplot-in-plotlyjs/64759)

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**Author:** [@stej](https://discourse.julialang.org/u/stej)\
**Replies:** 3\
**Last updated:** [July 19, 2021, 5:18pm UTC](https://discourse.julialang.org/t/treemap-subplot-in-plotlyjs/64759 "2021-07-19T17:18:06Z")

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I wanted to use a treemap in PlotlyJS. There is no method like this, so I create that by hand. fieldsa = Dict{Symbol,Any}(:type =\> "treemap", :labels =\> \["a", "A"\], :parents =\> \["", ""\], :values =\> \[1, 10\], …

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## [Sharing some great news - Julia Computing announces seed funding](https://discourse.julialang.org/t/sharing-some-great-news-julia-computing-announces-seed-funding/4346)

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**Author:** [@viralbshah](https://discourse.julialang.org/u/viralbshah)\
**Replies:** 5\
**Last updated:** [July 19, 2021, 5:14pm UTC](https://discourse.julialang.org/t/sharing-some-great-news-julia-computing-announces-seed-funding/4346 "2021-07-19T17:14:26Z")

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Hi everyone, I want to share some exciting news with all of you. Julia Computing successfully raised its first round of seed funding. This helps us double our commitment to open source, and also enables us to build some…

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## [Documenting elements of a struct](https://discourse.julialang.org/t/documenting-elements-of-a-struct/64769)

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**Author:** [@orome](https://discourse.julialang.org/u/orome)\
**Replies:** 37\
**Last updated:** [July 19, 2021, 3:55pm UTC](https://discourse.julialang.org/t/documenting-elements-of-a-struct/64769 "2021-07-19T15:55:01Z")

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How do I document the members of a struct so that Documenter generates documentation for them? """ This is an X """ struct X "This is a" a::String "This is b" b::Char "This is c" c end

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