# Latest

**URL:** https://discourse.julialang.org/latest.md?page=808

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

**Page:** 809

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## [Question about applying a customized branch and bound in Julia and the JuMP package](https://discourse.julialang.org/t/question-about-applying-a-customized-branch-and-bound-in-julia-and-the-jump-package/93136)

<div class="topic-metadata">

**Author:** [@Alex\_ricci](https://discourse.julialang.org/u/Alex_ricci)\
**Replies:** 3\
**Last updated:** [January 19, 2023, 2:34am UTC](https://discourse.julialang.org/t/question-about-applying-a-customized-branch-and-bound-in-julia-and-the-jump-package/93136 "2023-01-19T02:34:08Z")

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I am trying to develop a customised branch and bound algorithm in Julia with the JuMP package. The problem only has binary variables. What I do is relaxing the problem to its linear counterpart and getting the variable …

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## [Anybody know why this error occurs when trying to define a Catalyst @reaction\_network in Jupyter Notebooks?](https://discourse.julialang.org/t/anybody-know-why-this-error-occurs-when-trying-to-define-a-catalyst-reaction-network-in-jupyter-notebooks/93119)

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**Author:** [@jonathanfischer97](https://discourse.julialang.org/u/jonathanfischer97)\
**Replies:** 4\
**Last updated:** [January 19, 2023, 2:19am UTC](https://discourse.julialang.org/t/anybody-know-why-this-error-occurs-when-trying-to-define-a-catalyst-reaction-network-in-jupyter-notebooks/93119 "2023-01-19T02:19:35Z")

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## [\`@time\` output is a tiny bit noisy](https://discourse.julialang.org/t/time-output-is-a-tiny-bit-noisy/93113)

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**Author:** [@tfiers](https://discourse.julialang.org/u/tfiers)\
**Replies:** 6\
**Last updated:** [January 19, 2023, 12:03am UTC](https://discourse.julialang.org/t/time-output-is-a-tiny-bit-noisy/93113 "2023-01-19T00:03:00Z")

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Quick question, is there a mini-package that defines something like the following: using Printf macro time′(ex) # prime time # (saner name, e.g: htime, for 'human' time) quote t0 = time() $(…

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## [Summing and counting values in a df by row](https://discourse.julialang.org/t/summing-and-counting-values-in-a-df-by-row/60753)

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**Author:** [@Geoffysicist](https://discourse.julialang.org/u/Geoffysicist)\
**Replies:** 13\
**Last updated:** [January 18, 2023, 10:00pm UTC](https://discourse.julialang.org/t/summing-and-counting-values-in-a-df-by-row/60753 "2023-01-18T22:00:44Z")

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I have a dataframe of the form: 4×4 DataFrame Row │ ID Q1 Q2 Q3 │ Int64 Int64 Int64? Int64? ─────┼──────────────────────────────── 1 │ 1 1 0 1 2 │ 2 1 …

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## [Julia v1.9.0-beta3 is now available](https://discourse.julialang.org/t/julia-v1-9-0-beta3-is-now-available/93183)

<div class="topic-metadata">

**Author:** [@ararslan](https://discourse.julialang.org/u/ararslan)\
**Replies:** 0\
**Last updated:** [January 18, 2023, 9:45pm UTC](https://discourse.julialang.org/t/julia-v1-9-0-beta3-is-now-available/93183 "2023-01-18T21:45:43Z")

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The Julia developers are pleased to announce that v1.9.0-beta3, the third beta version for the upcoming 1.9 stable series, is now available. Binaries are available for download at https://julialang.org/downloads in the “…

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## [Difference between df\[:, :a\] and df\[!, :a\]](https://discourse.julialang.org/t/difference-between-df-a-and-df-a/28561)

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**Author:** [@mthelm85](https://discourse.julialang.org/u/mthelm85)\
**Replies:** 6\
**Last updated:** [September 9, 2019, 3:18pm UTC](https://discourse.julialang.org/t/difference-between-df-a-and-df-a/28561 "2019-09-09T15:18:39Z")

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I recently updated my DataFrames.jl package and noticed the following deprecation warning when doing df\[:a\]: Warning: \`getindex(df::DataFrame, col\_ind::ColumnIndex)\` is deprecated, use \`df\[!, col\_ind\]\` instead. I under…

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## [Please help me with the meaning of dot and three dots (...) in this code line:](https://discourse.julialang.org/t/please-help-me-with-the-meaning-of-dot-and-three-dots-in-this-code-line/93170)

<div class="topic-metadata">

**Author:** [@Kianoush\_Ramezani\_sh](https://discourse.julialang.org/u/Kianoush_Ramezani_sh)\
**Replies:** 5\
**Last updated:** [January 18, 2023, 9:07pm UTC](https://discourse.julialang.org/t/please-help-me-with-the-meaning-of-dot-and-three-dots-in-this-code-line/93170 "2023-01-18T21:07:38Z")

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(x → typeof(x)).(values(complexity\_of\_operators))…, Notes: complexity\_of\_operators is a dictionary I don’t know what the dot between the two parentheses means or what the … means at the end.

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## [\`@forward\` on vectors](https://discourse.julialang.org/t/forward-on-vectors/93121)

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**Author:** [@smartalecH](https://discourse.julialang.org/u/smartalecH)\
**Replies:** 4\
**Last updated:** [January 18, 2023, 8:36pm UTC](https://discourse.julialang.org/t/forward-on-vectors/93121 "2023-01-18T20:36:50Z")

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I recently learned about the “delegation” design pattern, and that there are numerous ways one could implement this within Julia. For example, the famous @forward macro makes it easy to “delegate” a set of methods meant …

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## [Static for loops](https://discourse.julialang.org/t/static-for-loops/93051)

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**Author:** [@gtgt](https://discourse.julialang.org/u/gtgt)\
**Replies:** 7\
**Last updated:** [January 17, 2023, 3:12pm UTC](https://discourse.julialang.org/t/static-for-loops/93051 "2023-01-17T15:12:36Z")

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I have a function f(::Val{m}) where m which I want to specialize to a few values. Can I do it in a for loop instead of writing all the specializations by hand? I tried for m in 1:3 f(Val(m)) end and for m in (1,…

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## [Unable to precompile Plots](https://discourse.julialang.org/t/unable-to-precompile-plots/92848)

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**Author:** [@HelloHelpp](https://discourse.julialang.org/u/HelloHelpp)\
**Replies:** 10\
**Last updated:** [January 18, 2023, 6:46pm UTC](https://discourse.julialang.org/t/unable-to-precompile-plots/92848 "2023-01-18T18:46:32Z")

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Hi all, I am unable to precompile the package Plots due to the following error: The following remedies have been attempted but so far none have been successful: -Uninstalling and reinstalling Julia -Adding and buildi…

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## [Median calculation performing better than expected](https://discourse.julialang.org/t/median-calculation-performing-better-than-expected/93174)

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**Author:** [@Nino\_Rode](https://discourse.julialang.org/u/Nino_Rode)\
**Replies:** 3\
**Last updated:** [January 18, 2023, 6:19pm UTC](https://discourse.julialang.org/t/median-calculation-performing-better-than-expected/93174 "2023-01-18T18:19:43Z")

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I have an “it works … why?” question. I hope this is the right place. I’m trying to learn to write julia code to have as good performance as possible (yes, I’m new with julia). Most of the time, I’m trying to reproduce …

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## [Before upgrading Julia version for the first time: What happens with the packages in each local environment?](https://discourse.julialang.org/t/before-upgrading-julia-version-for-the-first-time-what-happens-with-the-packages-in-each-local-environment/93175)

<div class="topic-metadata">

**Author:** [@martinmestre](https://discourse.julialang.org/u/martinmestre)\
**Replies:** 0\
**Last updated:** [January 18, 2023, 5:56pm UTC](https://discourse.julialang.org/t/before-upgrading-julia-version-for-the-first-time-what-happens-with-the-packages-in-each-local-environment/93175 "2023-01-18T17:56:47Z")

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Hi, first of all I would like to know the step by step procedure to upgrade Julia. I would also like to know what happens with the package versions I have in a local environment. How are them updated? If I keep older ju…

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## [ForwardDiff AD Error using distributed within Turing @model](https://discourse.julialang.org/t/forwarddiff-ad-error-using-distributed-within-turing-model/93111)

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**Author:** [@abhishek-venket](https://discourse.julialang.org/u/abhishek-venket)\
**Replies:** 0\
**Last updated:** [January 17, 2023, 7:17pm UTC](https://discourse.julialang.org/t/forwarddiff-ad-error-using-distributed-within-turing-model/93111 "2023-01-17T19:17:00Z")

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I am trying to estimate the posterior distributions of a couple of parameters of a system of ODEs. The probabilistic model is data ~ MvNormal(y\_sim, σ² \* I), where data contains sensor measurements of a quantity of inte…

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## [\`const\` syntax outside of \`struct\`](https://discourse.julialang.org/t/const-syntax-outside-of-struct/93173)

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**Author:** [@thevolatilebit](https://discourse.julialang.org/u/thevolatilebit)\
**Replies:** 0\
**Last updated:** [January 18, 2023, 5:15pm UTC](https://discourse.julialang.org/t/const-syntax-outside-of-struct/93173 "2023-01-18T17:15:41Z")

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Background: In Agents.jl, any agent type being made from calling @agent is mutable, but with Julia versions \>= 1.8 now we can specify particular fields as being const, which can help bring performance closer to immutabl…

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## [Using DifferentialEquations to solve a gravity problem results in runaway behaviour](https://discourse.julialang.org/t/using-differentialequations-to-solve-a-gravity-problem-results-in-runaway-behaviour/93140)

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**Author:** [@srikumarks](https://discourse.julialang.org/u/srikumarks)\
**Replies:** 6\
**Last updated:** [January 18, 2023, 5:16pm UTC](https://discourse.julialang.org/t/using-differentialequations-to-solve-a-gravity-problem-results-in-runaway-behaviour/93140 "2023-01-18T17:16:35Z")

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Hi, As a test and for learning, I’m using DifferentialEquations to solve a simple Newtonian gravity well motion problem. For the given initial conditions, I’m expecting circular motion, but I find that the orbit radius …

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## [Stochastic (L-)BFGS](https://discourse.julialang.org/t/stochastic-l-bfgs/93138)

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**Author:** [@jbrea](https://discourse.julialang.org/u/jbrea)\
**Replies:** 1\
**Last updated:** [January 18, 2023, 4:33pm UTC](https://discourse.julialang.org/t/stochastic-l-bfgs/93138 "2023-01-18T16:33:26Z")

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Anyone knows of a julia implementation of a stochastic (L-)BFGS variant, like e.g. described here or described here or implemented in pytorch here?

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## [Plotting surface with plots and pyplot](https://discourse.julialang.org/t/plotting-surface-with-plots-and-pyplot/93154)

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**Author:** [@neda](https://discourse.julialang.org/u/neda)\
**Replies:** 6\
**Last updated:** [January 18, 2023, 4:18pm UTC](https://discourse.julialang.org/t/plotting-surface-with-plots-and-pyplot/93154 "2023-01-18T16:18:04Z")

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I am trying to plot a 3D object with using Plots or PyPlot with the command surface. When I utilize Plots and surface(x,y,z) where x,y,z are three vectors with the same size, I get the message: \*\*\* IDENTICAL DATA POIN…

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## [\[ANN\] NestedGraphs.jl](https://discourse.julialang.org/t/ann-nestedgraphs-jl/93093)

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**Author:** [@filchristou](https://discourse.julialang.org/u/filchristou)\
**Replies:** 3\
**Last updated:** [January 18, 2023, 3:48pm UTC](https://discourse.julialang.org/t/ann-nestedgraphs-jl/93093 "2023-01-18T15:48:27Z")

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I would like to announce a new package for the Graphs ecosystem of julia: NestedGraphs.jl. As the name suggests, the package provides a way to handle nested graphs. It’s meant to offer type-stable support, although…

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## [Can the Genie Framework work with Makie and CairoMakie plots?](https://discourse.julialang.org/t/can-the-genie-framework-work-with-makie-and-cairomakie-plots/92609)

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**Author:** [@00krishna](https://discourse.julialang.org/u/00krishna)\
**Replies:** 1\
**Last updated:** [January 18, 2023, 3:10pm UTC](https://discourse.julialang.org/t/can-the-genie-framework-work-with-makie-and-cairomakie-plots/92609 "2023-01-18T15:10:30Z")

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I was looking into the Genie framework to build a webapp. It seems like there is some good integration between Genie and Plotly plots. However I was wondering whether Genie can work with Makie and CairoMakie plots. My sp…

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## [Improving performance of item response model in Turing.jl](https://discourse.julialang.org/t/improving-performance-of-item-response-model-in-turing-jl/86249)

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**Author:** [@p-gw](https://discourse.julialang.org/u/p-gw)\
**Replies:** 23\
**Last updated:** [January 18, 2023, 3:06pm UTC](https://discourse.julialang.org/t/improving-performance-of-item-response-model-in-turing-jl/86249 "2023-01-18T15:06:52Z")

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Hi everyone, I am trying to fit an item response model in Turing.jl and have some questions regarding performance. This question is related to Making Turing Fast with large numbers of parameters? and in fact is referenc…

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## [Data Visualization](https://discourse.julialang.org/t/data-visualization/93160)

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**Author:** [@BadBoy](https://discourse.julialang.org/u/BadBoy)\
**Replies:** 1\
**Last updated:** [January 18, 2023, 3:04pm UTC](https://discourse.julialang.org/t/data-visualization/93160 "2023-01-18T15:04:45Z")

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Suppose one data frame has two categorical variables, one is gender(male and female) and other one is smoking status(smokes, never smoked, formerly smokes, unknown) . Now how do we get a grouped bar plot of the smoking s…

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## [How can I convert a bitstring to the binary form](https://discourse.julialang.org/t/how-can-i-convert-a-bitstring-to-the-binary-form/93134)

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**Author:** [@dmtrung14](https://discourse.julialang.org/u/dmtrung14)\
**Replies:** 6\
**Last updated:** [January 18, 2023, 2:54pm UTC](https://discourse.julialang.org/t/how-can-i-convert-a-bitstring-to-the-binary-form/93134 "2023-01-18T14:54:22Z")

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I am using bitstring to perform an xor operation on the ith bit of a string: string = bitstring(string ⊻ 1 \<\<i) However the result will be a string, so I cannot continue with other i. So I want to know how do I conver…

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## [VS Code Remote - command 'language-julia.executeJuliaCodeInREPL' not found](https://discourse.julialang.org/t/vs-code-remote-command-language-julia-executejuliacodeinrepl-not-found/93101)

<div class="topic-metadata">

**Author:** [@bernhard](https://discourse.julialang.org/u/bernhard)\
**Replies:** 7\
**Last updated:** [January 18, 2023, 2:37pm UTC](https://discourse.julialang.org/t/vs-code-remote-command-language-julia-executejuliacodeinrepl-not-found/93101 "2023-01-18T14:37:30Z")

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Hi I am trying out VS Code remote via SSH tunnel. I usually run code via CTRL+Enter (runs the line where the cursor is, or the selection). This shortcut works on my local computer in VS code. It also works on the remo…

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## [Gamma\_inc derivatives](https://discourse.julialang.org/t/gamma-inc-derivatives/93148)

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**Author:** [@lrnv](https://discourse.julialang.org/u/lrnv)\
**Replies:** 5\
**Last updated:** [January 18, 2023, 2:00pm UTC](https://discourse.julialang.org/t/gamma-inc-derivatives/93148 "2023-01-18T14:00:36Z")

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\[Largely edited version\] I was looking at this issue about the derivative of the incomplete gamma function w.r.t the parameter a. Looks like from this page of wolfram alpha docs that the right formula is : which dep…

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## [Julia multiprocessing](https://discourse.julialang.org/t/julia-multiprocessing/93150)

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**Author:** [@Sudipta\_Chakraborty](https://discourse.julialang.org/u/Sudipta_Chakraborty)\
**Replies:** 1\
**Last updated:** [January 18, 2023, 12:33pm UTC](https://discourse.julialang.org/t/julia-multiprocessing/93150 "2023-01-18T12:33:32Z")

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Here is my python code for multiprocessing. How can I write this in Julia? if eris.NumProc \> 1: global pair\_check PL1, PL2 = mul\_e\_pairs(nocc) def pair\_check(…

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## [Multiple Plots for Parametric Equations](https://discourse.julialang.org/t/multiple-plots-for-parametric-equations/93131)

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**Author:** [@Freya\_the\_Goddess](https://discourse.julialang.org/u/Freya_the_Goddess)\
**Replies:** 7\
**Last updated:** [January 18, 2023, 12:00pm UTC](https://discourse.julialang.org/t/multiple-plots-for-parametric-equations/93131 "2023-01-18T12:00:00Z")

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Hi all, I want to do multiple plots with layout for parametric equations. This is my code: using Plots, LaTeXStrings pyplot() θ1 = 0:0.1:2π x1 = 3 .\*cos.(θ1) y1 = 3 .\*sin.(θ1) x2 = 3 .\*cos.(θ1) y2 = sin.(θ1) θ2 = 0:…

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## [Help me understand vector initialization](https://discourse.julialang.org/t/help-me-understand-vector-initialization/93129)

<div class="topic-metadata">

**Author:** [@udax](https://discourse.julialang.org/u/udax)\
**Replies:** 7\
**Last updated:** [January 18, 2023, 11:01am UTC](https://discourse.julialang.org/t/help-me-understand-vector-initialization/93129 "2023-01-18T11:01:50Z")

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Here is a MWE of a problem that I am facing. In method 1, the array “arr” gets initialized correctly, but it seems very inelegant. In the second method, the array “brr” often does not get initialized correctly. for k = …

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## [XSLT.jl: transform XML documents using XSLT stylesheets](https://discourse.julialang.org/t/xslt-jl-transform-xml-documents-using-xslt-stylesheets/92991)

<div class="topic-metadata">

**Author:** [@rvezy](https://discourse.julialang.org/u/rvezy)\
**Replies:** 5\
**Last updated:** [January 18, 2023, 9:11am UTC](https://discourse.julialang.org/t/xslt-jl-transform-xml-documents-using-xslt-stylesheets/92991 "2023-01-18T09:11:11Z")

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This weekend I developed XSLT.jl, a package to transform XML documents to any other document type using XSLT stylesheets. This is a Julia wrapper for the libxslt library, which was already somewhat present in JuliaBinary…

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## [Poincare map DifferentialEquations.jl](https://discourse.julialang.org/t/poincare-map-differentialequations-jl/92308)

<div class="topic-metadata">

**Author:** [@Sergey\_Novak](https://discourse.julialang.org/u/Sergey_Novak)\
**Replies:** 14\
**Last updated:** [January 18, 2023, 9:02am UTC](https://discourse.julialang.org/t/poincare-map-differentialequations-jl/92308 "2023-01-18T09:02:24Z")

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Hello, i have system: function model(u, p ,t) E, x, u\_, y = u τ, α, τ\_D, J, U0, ΔU0, τ\_y, β, xthr, ythr, I0 = p U(y, U0, ΔU0, ythr) = U0 + ΔU0 / ( 1 + exp( -50 \* ( y - ythr ) ) ) σ(x, xthr)= 1 …

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## [Use of linear operators on a GPU](https://discourse.julialang.org/t/use-of-linear-operators-on-a-gpu/92899)

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**Author:** [@shakedregev](https://discourse.julialang.org/u/shakedregev)\
**Replies:** 3\
**Last updated:** [January 18, 2023, 7:12am UTC](https://discourse.julialang.org/t/use-of-linear-operators-on-a-gpu/92899 "2023-01-18T07:12:19Z")

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Say I have a sparse matrices $A$ and $B=D\*A^T$ and their product is dense. I want to solve systems with them using an iterative method from Krylov.jl. On a CPU, I can do opC =LinearOperator(A)\*LinearOperator(B) cg(opC,…

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