# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?page=279

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**Page:** 280

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## [DataFrames - reduce allocations and improve speed](https://discourse.julialang.org/t/dataframes-reduce-allocations-and-improve-speed/81380)

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**Author:** [@bojusemo](https://discourse.julialang.org/u/bojusemo)\
**Replies:** 5\
**Last updated:** [May 22, 2022, 2:52pm UTC](https://discourse.julialang.org/t/dataframes-reduce-allocations-and-improve-speed/81380 "2022-05-22T14:52:06Z")

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Hello folks, I have two huge data frames (described below) and I’m running my\_module.f5(df1, df2) based on the module and functions described below. The code works with small data frames, but when I run it with those bi…

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## [Issue with Local Sensitivites and dt \<= dtmin](https://discourse.julialang.org/t/issue-with-local-sensitivites-and-dt-dtmin/81426)

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**Author:** [@xztt](https://discourse.julialang.org/u/xztt)\
**Replies:** 4\
**Last updated:** [May 22, 2022, 12:14pm UTC](https://discourse.julialang.org/t/issue-with-local-sensitivites-and-dt-dtmin/81426 "2022-05-22T12:14:33Z")

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Hi, I am trying to calculate the local sensitivities for a large circulation model (Shi 2006) I am Importing the model using CellML.jl when I define an ODEproblem and simulate the solution appears fine and also when pe…

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## [Superexpressive Activation function (paper) and "Three Hidden Layers Are Enough" paper](https://discourse.julialang.org/t/superexpressive-activation-function-paper-and-three-hidden-layers-are-enough-paper/81336)

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**Author:** [@Palli](https://discourse.julialang.org/u/Palli)\
**Replies:** 1\
**Last updated:** [May 22, 2022, 1:25am UTC](https://discourse.julialang.org/t/superexpressive-activation-function-paper-and-three-hidden-layers-are-enough-paper/81336 "2022-05-22T01:25:15Z")

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I came across Superexpressive Activation functions, the elementary kind on arxiv, the paper on it is also at: A. Elementary Superexpressive Activations http://proceedings.mlr.press/v139/yarotsky21a/yarotsky21a.pdf we…

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## [\[sparse modelling\] Does JuMP automatically remove "uninfluent" variables from constraints/objective?](https://discourse.julialang.org/t/sparse-modelling-does-jump-automatically-remove-uninfluent-variables-from-constraints-objective/81366)

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**Author:** [@sylvaticus](https://discourse.julialang.org/u/sylvaticus)\
**Replies:** 6\
**Last updated:** [May 22, 2022, 12:13am UTC](https://discourse.julialang.org/t/sparse-modelling-does-jump-automatically-remove-uninfluent-variables-from-constraints-objective/81366 "2022-05-22T00:13:02Z")

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Hello, I am designing a non-linear model where some quantities depend from many variables, but only a few of them actually have a parameter that allow the dependent variable to play. The actual implementation is: quant…

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## [Makie | First item in GridLayout not displayed](https://discourse.julialang.org/t/makie-first-item-in-gridlayout-not-displayed/81353)

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**Author:** [@Audrius-St](https://discourse.julialang.org/u/Audrius-St)\
**Replies:** 2\
**Last updated:** [May 20, 2022, 8:25pm UTC](https://discourse.julialang.org/t/makie-first-item-in-gridlayout-not-displayed/81353 "2022-05-20T20:25:26Z")

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Hello, OS: Windows 11 Julia: 1.7.2 Makie: 0.17.2 The first item “Patient” in the following nested GridLayout is not being displayed: Code fragment: # Figure for GLMakie display noto\_sans = assetpath("NotoSans-Re…

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## [Examples of MVC or other UI pattern for Makie](https://discourse.julialang.org/t/examples-of-mvc-or-other-ui-pattern-for-makie/53489)

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**Author:** [@airpmb](https://discourse.julialang.org/u/airpmb)\
**Replies:** 1\
**Last updated:** [May 20, 2022, 7:02pm UTC](https://discourse.julialang.org/t/examples-of-mvc-or-other-ui-pattern-for-makie/53489 "2022-05-20T19:02:03Z")

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I’m trying to put together a simple GUI using Makie and the latest layout awesomeness and realizing that most of the challenge is figuring out how best to implement something like MVC (Model-View-Controller) or whatever …

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## [EEGLAB .set Format in Julia](https://discourse.julialang.org/t/eeglab-set-format-in-julia/81037)

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**Author:** [@duodenum](https://discourse.julialang.org/u/duodenum)\
**Replies:** 3\
**Last updated:** [May 20, 2022, 6:57pm UTC](https://discourse.julialang.org/t/eeglab-set-format-in-julia/81037 "2022-05-20T18:57:36Z")

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Hello, I’m a neuroscientist considering switching to Julia. I’m writing some functions and got a bit frustrated with MATLAB. My question is: is there a way to import EEGLAB .set format to Julia, similar to for example p…

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## [Using streamplot with PyPlot backend in Plots](https://discourse.julialang.org/t/using-streamplot-with-pyplot-backend-in-plots/81278)

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**Author:** [@cmdenis](https://discourse.julialang.org/u/cmdenis)\
**Replies:** 5\
**Last updated:** [May 20, 2022, 4:02pm UTC](https://discourse.julialang.org/t/using-streamplot-with-pyplot-backend-in-plots/81278 "2022-05-20T16:02:05Z")

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Hello, I don’t have a strong understanding of how Plots work, but as far as I know, it serves as an API that uses backend plotting systems, like matplotlib or gr. This allows the user to use similar (if not identical) s…

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## [LibPQ connection with keepalive parameters](https://discourse.julialang.org/t/libpq-connection-with-keepalive-parameters/81379)

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**Author:** [@Laco\_Kovac](https://discourse.julialang.org/u/Laco_Kovac)\
**Replies:** 0\
**Last updated:** [May 20, 2022, 3:09pm UTC](https://discourse.julialang.org/t/libpq-connection-with-keepalive-parameters/81379 "2022-05-20T15:09:17Z")

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Is it possible to specify keepalive parameters for LibPQ connection? Thank you,

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## [ReinforcementLearning.jl vs POMDPs.jl](https://discourse.julialang.org/t/reinforcementlearning-jl-vs-pomdps-jl/81355)

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**Author:** [@filchristou](https://discourse.julialang.org/u/filchristou)\
**Replies:** 0\
**Last updated:** [May 20, 2022, 10:17am UTC](https://discourse.julialang.org/t/reinforcementlearning-jl-vs-pomdps-jl/81355 "2022-05-20T10:17:42Z")

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Hello. Some weeks ago, there was a live session regarding the ReinforcementLearning.jl package, and some of the questions were to identify differences, overlaps, and cooperation opportunities with the JuliaPOMDP organiza…

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## [Is it possible to unsynch the EnsembleGPUArrays?](https://discourse.julialang.org/t/is-it-possible-to-unsynch-the-ensemblegpuarrays/77879)

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**Author:** [@Marius\_123](https://discourse.julialang.org/u/Marius_123)\
**Replies:** 6\
**Last updated:** [May 20, 2022, 9:35am UTC](https://discourse.julialang.org/t/is-it-possible-to-unsynch-the-ensemblegpuarrays/77879 "2022-05-20T09:35:52Z")

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Hello, i want to solve multiple ODEs in parallel on the GPU, is it possible to do this unsynchronized? As stated in the DiffEqGPU, all trajectories have the same time stepping. This slows down the solving if one trajecto…

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## [How to lookup and assign on label-aware AbstractVectors in various packages](https://discourse.julialang.org/t/how-to-lookup-and-assign-on-label-aware-abstractvectors-in-various-packages/81309)

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**Author:** [@sylvaticus](https://discourse.julialang.org/u/sylvaticus)\
**Replies:** 1\
**Last updated:** [May 20, 2022, 7:44am UTC](https://discourse.julialang.org/t/how-to-lookup-and-assign-on-label-aware-abstractvectors-in-various-packages/81309 "2022-05-20T07:44:00Z")

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Sometimes I do not remember the position of dimensions or of the individual indexes in a multi-dimensional array and when performances are not a critical factor I prefer to work on keys rather than position. I am hence …

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## [FIR Filter Implementation in Julia](https://discourse.julialang.org/t/fir-filter-implementation-in-julia/81331)

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**Author:** [@duodenum](https://discourse.julialang.org/u/duodenum)\
**Replies:** 2\
**Last updated:** [May 20, 2022, 5:26am UTC](https://discourse.julialang.org/t/fir-filter-implementation-in-julia/81331 "2022-05-20T05:26:25Z")

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Hello all, I’m trying to replicate this MATLAB code in Julia for zero-phase filtering: d = designfilt('bandpassfir', 'StopbandFrequency1', 1e-9, ... 'PassbandFrequency1', 35, 'PassbandFrequency2', 45, ... 'Stop…

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## [ModelingToolkit vs plain DifferentialEquations](https://discourse.julialang.org/t/modelingtoolkit-vs-plain-differentialequations/81322)

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**Author:** [@mzhenirovskyy](https://discourse.julialang.org/u/mzhenirovskyy)\
**Replies:** 12\
**Last updated:** [May 20, 2022, 3:42am UTC](https://discourse.julialang.org/t/modelingtoolkit-vs-plain-differentialequations/81322 "2022-05-20T03:42:45Z")

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Hi All, What is the magic that happens inside of the “ModelingToolkit.ODESystem”? When I have the DAE system in the next form: using DifferentialEquations, OrdinaryDiffEq, Sundials u0 = \[0.0, 0.0, 0.0, 0.0, 0.0, 0.0…

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## [JuMP turning off/on a constraint](https://discourse.julialang.org/t/jump-turning-off-on-a-constraint/81268)

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**Author:** [@jvaes](https://discourse.julialang.org/u/jvaes)\
**Replies:** 6\
**Last updated:** [May 19, 2022, 10:19pm UTC](https://discourse.julialang.org/t/jump-turning-off-on-a-constraint/81268 "2022-05-19T22:19:38Z")

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Hi there, I was wondering if JuMP has a way to turn off/on a constraint. According to the documentation, I can delete a constraint using the function delete (and then unregister if I want) but I cannot find a way to tu…

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## [Code that works fine distributed across processes on one node using slurm seems to fail when trying to generate workers across many](https://discourse.julialang.org/t/code-that-works-fine-distributed-across-processes-on-one-node-using-slurm-seems-to-fail-when-trying-to-generate-workers-across-many/39359)

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**Author:** [@HarrisonWilde](https://discourse.julialang.org/u/HarrisonWilde)\
**Replies:** 2\
**Last updated:** [May 19, 2022, 4:15pm UTC](https://discourse.julialang.org/t/code-that-works-fine-distributed-across-processes-on-one-node-using-slurm-seems-to-fail-when-trying-to-generate-workers-across-many/39359 "2022-05-19T16:15:51Z")

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Hi, I have some code that works fine when I run it on a single node of our slurm cluster using sbatch, but when I try to run it on multiple nodes I get errors similar to the following: srun: error: cnode22: tasks 7,12,1…

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## [Is there a way to stop optimization process when feasible solution is found?](https://discourse.julialang.org/t/is-there-a-way-to-stop-optimization-process-when-feasible-solution-is-found/81025)

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**Author:** [@afazevedo](https://discourse.julialang.org/u/afazevedo)\
**Replies:** 4\
**Last updated:** [May 19, 2022, 2:44pm UTC](https://discourse.julialang.org/t/is-there-a-way-to-stop-optimization-process-when-feasible-solution-is-found/81025 "2022-05-19T14:44:23Z")

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Hey there. I am solving a problem with lazy constraints using MOI callback interface. I want to know if there is a way to stop the branch-and-bound process when finding a new incumbent solution that is feasible? I don’t…

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## [User cuts for BilevelJuMP model](https://discourse.julialang.org/t/user-cuts-for-bileveljump-model/81299)

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**Author:** [@math\_opt](https://discourse.julialang.org/u/math_opt)\
**Replies:** 3\
**Last updated:** [May 19, 2022, 2:30pm UTC](https://discourse.julialang.org/t/user-cuts-for-bileveljump-model/81299 "2022-05-19T14:30:15Z")

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How do I add cuts during the solve process when using BilevelJuMP.jl. My upper-level objective is a sum of binary variables and thus I know that my solution (optimal objective value) is eventually going to be an integer …

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## [Access both solutions of a SecondOrderODEProblem solution](https://discourse.julialang.org/t/access-both-solutions-of-a-secondorderodeproblem-solution/81291)

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**Author:** [@GHRALIMA](https://discourse.julialang.org/u/GHRALIMA)\
**Replies:** 7\
**Last updated:** [May 19, 2022, 2:10pm UTC](https://discourse.julialang.org/t/access-both-solutions-of-a-secondorderodeproblem-solution/81291 "2022-05-19T14:10:43Z")

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I’m trying to use DifferentialEquations.jl to solve simple mechanical problems with SecondOrderODEProblem, something like: k=0.01 v0 = 10.0 x0 = 10.0 tspan = (0.0, 100.0) ax1(v,u,p,t) = -k\*v - g prob = SecondOrderODEPr…

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## [differentialEquation or diffEqOperator, whose problem?](https://discourse.julialang.org/t/differentialequation-or-diffeqoperator-whose-problem/81179)

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**Author:** [@Fred\_He](https://discourse.julialang.org/u/Fred_He)\
**Replies:** 5\
**Last updated:** [May 19, 2022, 12:19pm UTC](https://discourse.julialang.org/t/differentialequation-or-diffeqoperator-whose-problem/81179 "2022-05-19T12:19:33Z")

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basically, I would like to simulate a gas-solid reaction. u\[:,1\] is gas reactant, u\[:,2\] is gas product, and u\[:3\] is solid product. some times the result is strange. the code is below using OrdinaryDiffEq, DiffEqOpera…

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## [Easier use of generated\_quantities](https://discourse.julialang.org/t/easier-use-of-generated-quantities/81305)

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**Author:** [@wc4wc4wc4](https://discourse.julialang.org/u/wc4wc4wc4)\
**Replies:** 0\
**Last updated:** [May 19, 2022, 10:17am UTC](https://discourse.julialang.org/t/easier-use-of-generated-quantities/81305 "2022-05-19T10:17:40Z")

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Hi, I’ve had a problem where I had to deal with generated\_quantities and I’ve come up with a solution myself, but I pretty sure that it’s not the optimal way of doing it. No matter what, I think it would be a great help…

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## [The fate of DimensionalArrays / AxisArrays in Julia, and which to actually use](https://discourse.julialang.org/t/the-fate-of-dimensionalarrays-axisarrays-in-julia-and-which-to-actually-use/33253)

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**Author:** [@Datseris](https://discourse.julialang.org/u/Datseris)\
**Replies:** 7\
**Last updated:** [May 19, 2022, 8:09am UTC](https://discourse.julialang.org/t/the-fate-of-dimensionalarrays-axisarrays-in-julia-and-which-to-actually-use/33253 "2022-05-19T08:09:30Z")

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I wasn’t sure whether I should open this at “Domains” or “Community”, given how many different areas it touches So, as far as I can tell, at the moment the story of using array data coupled with information about dimens…

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## [DFTK school 2022](https://discourse.julialang.org/t/dftk-school-2022/73497)

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**Author:** [@mfh](https://discourse.julialang.org/u/mfh)\
**Replies:** 6\
**Last updated:** [May 19, 2022, 5:17am UTC](https://discourse.julialang.org/t/dftk-school-2022/73497 "2022-05-19T05:17:17Z")

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Hi everyone! From 29 to 31 Aug 2022 @antoine-levitt, Eric Cancès (from École des Ponts in Paris) and myself, we will organize an interdisciplinary summer school centred around electronic-structure simulations and method…

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## [Modelling Microstructure Noise Using Hawkes Processes](https://discourse.julialang.org/t/modelling-microstructure-noise-using-hawkes-processes/81298)

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**Author:** [@dm13450](https://discourse.julialang.org/u/dm13450)\
**Replies:** 0\
**Last updated:** [May 19, 2022, 5:06am UTC](https://discourse.julialang.org/t/modelling-microstructure-noise-using-hawkes-processes/81298 "2022-05-19T05:06:22Z")

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Using Julia I’ve shown how you can use Hawkes processes to model the high frequency phenomenon of microstructure noise. This is where the volatility of an asset blows up as you move to smaller timescales. My post is wri…

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## [Wording in "Test summary" portion of HypothesisTests.jl output](https://discourse.julialang.org/t/wording-in-test-summary-portion-of-hypothesistests-jl-output/79186)

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**Author:** [@nealS](https://discourse.julialang.org/u/nealS)\
**Replies:** 1\
**Last updated:** [May 19, 2022, 4:13am UTC](https://discourse.julialang.org/t/wording-in-test-summary-portion-of-hypothesistests-jl-output/79186 "2022-05-19T04:13:04Z")

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I am a bit confused about the wording in the output of the hypothesis tests implemented in Hypothesistests.jl, and think that they might be improved. Take this instance of Fisher’s exact test: FisherExactTest(4,3,2,4) F…

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## [Bivariate normal in Turing](https://discourse.julialang.org/t/bivariate-normal-in-turing/53446)

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**Author:** [@drbenvincent](https://discourse.julialang.org/u/drbenvincent)\
**Replies:** 5\
**Last updated:** [May 18, 2022, 10:07pm UTC](https://discourse.julialang.org/t/bivariate-normal-in-turing/53446 "2022-05-18T22:07:23Z")

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I’m just starting to get to grips with Turing, and enjoying it very much so far. But I’ve run up against a problem with a bivariate normal prior. using Turing, StatsPlots @model function pearson\_correlation(x) rows…

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## [Implementation of householder/reflection matrices with efficient multiplication?](https://discourse.julialang.org/t/implementation-of-householder-reflection-matrices-with-efficient-multiplication/81257)

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**Author:** [@ptonner](https://discourse.julialang.org/u/ptonner)\
**Replies:** 5\
**Last updated:** [May 18, 2022, 3:09pm UTC](https://discourse.julialang.org/t/implementation-of-householder-reflection-matrices-with-efficient-multiplication/81257 "2022-05-18T15:09:02Z")

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Is there a standard implementation of reflector/householder matrices and their efficient multiplication with vectors (e.g. O(n) cost)? I don’t think this would be hard to implement for my specific purposes, but for that…

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## [HTTP: Login to MediaWiki API with post fails (works with python)](https://discourse.julialang.org/t/http-login-to-mediawiki-api-with-post-fails-works-with-python/41657)

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**Author:** [@zweiglimmergneis](https://discourse.julialang.org/u/zweiglimmergneis)\
**Replies:** 5\
**Last updated:** [May 18, 2022, 10:48am UTC](https://discourse.julialang.org/t/http-login-to-mediawiki-api-with-post-fails-works-with-python/41657 "2022-05-18T10:48:49Z")

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Why can I login with python (module requests), but not with HTTP.jl? The MediaWiki API requires a login token, a bot user name and password. See python-code example. Bot user name looks like “user@juliahttp”. The passwo…

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## [How to extract weights from SimpleWeightedEdge (from kruskal\_mst)](https://discourse.julialang.org/t/how-to-extract-weights-from-simpleweightededge-from-kruskal-mst/81192)

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**Author:** [@JedPhillips](https://discourse.julialang.org/u/JedPhillips)\
**Replies:** 5\
**Last updated:** [May 18, 2022, 7:19am UTC](https://discourse.julialang.org/t/how-to-extract-weights-from-simpleweightededge-from-kruskal-mst/81192 "2022-05-18T07:19:34Z")

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I’m trying to figure out how to interact with a minimal spanning tree object returned by Graphs.kruskal\_mst(). I just can’t figure out how to extract the resulting edge wights (or the edges). Here’s a minimal code to sh…

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## [How to set different linestyles in Makie Series plot](https://discourse.julialang.org/t/how-to-set-different-linestyles-in-makie-series-plot/75818)

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**Author:** [@bgctw](https://discourse.julialang.org/u/bgctw)\
**Replies:** 1\
**Last updated:** [May 18, 2022, 6:04am UTC](https://discourse.julialang.org/t/how-to-set-different-linestyles-in-makie-series-plot/75818 "2022-05-18T06:04:11Z")

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The Makie series command can be used to plot several lines of a matrix. I found an documentation example that shows how to set different labels and colors for the different lines. Could someone hint me to documentatio…

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