# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?page=162

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**Page:** 163

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## [Looking for a constrained optimization algorithm](https://discourse.julialang.org/t/looking-for-a-constrained-optimization-algorithm/104799)

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**Author:** [@Tamas\_Papp](https://discourse.julialang.org/u/Tamas_Papp)\
**Replies:** 7\
**Last updated:** [October 10, 2023, 1:32pm UTC](https://discourse.julialang.org/t/looking-for-a-constrained-optimization-algorithm/104799 "2023-10-10T13:32:00Z")

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After solving some structural estimation problems in economics with existing tools, I have a more clear idea of the kind of algorithm I am looking for. AFAICT no existing Julia package exists that does everything below —…

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## [Add DICOMTree.jl to JuliaHealth organisation?](https://discourse.julialang.org/t/add-dicomtree-jl-to-juliahealth-organisation/102873)

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**Author:** [@fdekerme](https://discourse.julialang.org/u/fdekerme)\
**Replies:** 2\
**Last updated:** [October 10, 2023, 1:28pm UTC](https://discourse.julialang.org/t/add-dicomtree-jl-to-juliahealth-organisation/102873 "2023-10-10T13:28:54Z")

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Hello ! :grin: Continuing the discussion from \[ANN\] DICOMTree.jl: fdekerme/DICOMTree.jl: A small Julia tool for visualizing DICOM metadata. (github.com) I have recently published a new DICOMTree package which has just…

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## [Interim values of Metaheuristics optimiziers](https://discourse.julialang.org/t/interim-values-of-metaheuristics-optimiziers/104768)

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**Author:** [@jcusick](https://discourse.julialang.org/u/jcusick)\
**Replies:** 3\
**Last updated:** [October 10, 2023, 12:45pm UTC](https://discourse.julialang.org/t/interim-values-of-metaheuristics-optimiziers/104768 "2023-10-10T12:45:31Z")

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I’m interested in getting the interim population values for algorithms within Metaheuristics.jl at each timestep, for example Differential Evolution. I’ve seen examples where the single member of the population with the…

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## [Modeling a leaking tank](https://discourse.julialang.org/t/modeling-a-leaking-tank/104750)

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**Author:** [@lsablon](https://discourse.julialang.org/u/lsablon)\
**Replies:** 5\
**Last updated:** [October 10, 2023, 8:39am UTC](https://discourse.julialang.org/t/modeling-a-leaking-tank/104750 "2023-10-10T08:39:51Z")

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Hello ! I’m currently working on modeling a system that resembles an open-topped tank with a leak, where the tank is also being supplied, so if the leak isn’t sufficient, it overflows. The system’s equations (reasonabl…

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## [Help with a JuMP.jl problem](https://discourse.julialang.org/t/help-with-a-jump-jl-problem/104778)

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**Author:** [@mthelm85](https://discourse.julialang.org/u/mthelm85)\
**Replies:** 1\
**Last updated:** [October 10, 2023, 5:48am UTC](https://discourse.julialang.org/t/help-with-a-jump-jl-problem/104778 "2023-10-10T05:48:52Z")

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The task is fairly straightforward. I need to group the numbers in A into pairs, such that the sum of each pair corresponds to one of the numbers in S. using HiGHS using JuMP m = Model(HiGHS.Optimizer) A = \[ 119 225 5…

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## [On the future of Flux.destructure and SciML integration](https://discourse.julialang.org/t/on-the-future-of-flux-destructure-and-sciml-integration/104760)

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**Author:** [@Bizzi](https://discourse.julialang.org/u/Bizzi)\
**Replies:** 4\
**Last updated:** [October 9, 2023, 8:24pm UTC](https://discourse.julialang.org/t/on-the-future-of-flux-destructure-and-sciml-integration/104760 "2023-10-09T20:24:50Z")

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Due to some technical limitations regarding Lux and coupling layers (1, 2, 3) and the existence of InvertibleNetworks.jl, I have chosen to use Flux for my designs. Still, my long-term objective would be to use Optimizati…

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## [Set parameter dependent time steps using OrdinaryDiffEq](https://discourse.julialang.org/t/set-parameter-dependent-time-steps-using-ordinarydiffeq/104759)

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**Author:** [@henry2004y](https://discourse.julialang.org/u/henry2004y)\
**Replies:** 2\
**Last updated:** [October 9, 2023, 6:09pm UTC](https://discourse.julialang.org/t/set-parameter-dependent-time-steps-using-ordinarydiffeq/104759 "2023-10-09T18:09:24Z")

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Hi, I have a question about how to set time-dependent time steps (or maximum time steps) for solving an ODE. For a quick demo, say we are dealing with this simple ODE: using OrdinaryDiffEq f(u, p, t) = 1.01 \* p \* u u0…

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## [Custom Markershapes in Plots jl](https://discourse.julialang.org/t/custom-markershapes-in-plots-jl/104542)

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**Author:** [@Gattu\_Mytraya](https://discourse.julialang.org/u/Gattu_Mytraya)\
**Replies:** 4\
**Last updated:** [October 4, 2023, 2:39pm UTC](https://discourse.julialang.org/t/custom-markershapes-in-plots-jl/104542 "2023-10-04T14:39:27Z")

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I would like to use custom marker shapes (I hope to import them as SVG files) in scatterplots using Plots jl. How can I do this?

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## [Why does my Flux model return in all NaN?](https://discourse.julialang.org/t/why-does-my-flux-model-return-in-all-nan/104742)

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**Author:** [@tiZ](https://discourse.julialang.org/u/tiZ)\
**Replies:** 2\
**Last updated:** [October 9, 2023, 6:59am UTC](https://discourse.julialang.org/t/why-does-my-flux-model-return-in-all-nan/104742 "2023-10-09T06:59:38Z")

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Hi friends here, I would like to ask a question about the Flux training, and I am try to understand why my model will return NaN value after a failed training step. for example I have such a model, input shape of it is…

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## [Setting up gurobi environment inside a module](https://discourse.julialang.org/t/setting-up-gurobi-environment-inside-a-module/104736)

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**Author:** [@math\_opt](https://discourse.julialang.org/u/math_opt)\
**Replies:** 8\
**Last updated:** [October 9, 2023, 2:22pm UTC](https://discourse.julialang.org/t/setting-up-gurobi-environment-inside-a-module/104736 "2023-10-09T14:22:52Z")

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I have a module that has some functions that run some optimization problems modeling using the JuMP package and the Gurobi solver. a very generic structure of the code is as follows: module TestModule using JuMP using…

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## [\[RFC\] GraphInterface.jl: An interface proposal for Graphs.jl version 2.0](https://discourse.julialang.org/t/rfc-graphinterface-jl-an-interface-proposal-for-graphs-jl-version-2-0/104518)

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**Author:** [@CameronBieganek](https://discourse.julialang.org/u/CameronBieganek)\
**Replies:** 29\
**Last updated:** [October 8, 2023, 10:00pm UTC](https://discourse.julialang.org/t/rfc-graphinterface-jl-an-interface-proposal-for-graphs-jl-version-2-0/104518 "2023-10-08T22:00:07Z")

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Hi, all! I’ve created a new package GraphInterface.jl as a proposal for the new AbstractGraph interface for Graphs.jl version 2.0. I know that there is ongoing work in the GraphsBase.jl repository on the new version 2.0 …

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## [Question about the syntax of the @constraint command](https://discourse.julialang.org/t/question-about-the-syntax-of-the-constraint-command/104700)

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**Author:** [@Artemisa\_Fontinele](https://discourse.julialang.org/u/Artemisa_Fontinele)\
**Replies:** 7\
**Last updated:** [October 8, 2023, 10:18am UTC](https://discourse.julialang.org/t/question-about-the-syntax-of-the-constraint-command/104700 "2023-10-08T10:18:13Z")

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Hey guys! I’ve just started programming in julia and I want to implement two constraints for my code using the JuMP library. The constraints are: for i in 1:N for j in 1:N If sum of Xji == 0 then sum of Xij \>=2 If …

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## [Where is backslash (\\) implemented?](https://discourse.julialang.org/t/where-is-backslash-implemented/104693)

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**Author:** [@SupernovaTitanium](https://discourse.julialang.org/u/SupernovaTitanium)\
**Replies:** 9\
**Last updated:** [October 8, 2023, 8:08am UTC](https://discourse.julialang.org/t/where-is-backslash-implemented/104693 "2023-10-08T08:08:15Z")

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Hi, I’m new to Julia. Recently, I’ve used the backslash (\\) operator to solve a linear system. However, I don’t know how it is implemented. I wanted to know it so I traced the code. I am able to locate to line 1110 at j…

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## [Fixing plot position during an animation for CairoMakie](https://discourse.julialang.org/t/fixing-plot-position-during-an-animation-for-cairomakie/104709)

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**Author:** [@Varun\_V](https://discourse.julialang.org/u/Varun_V)\
**Replies:** 1\
**Last updated:** [October 7, 2023, 9:16pm UTC](https://discourse.julialang.org/t/fixing-plot-position-during-an-animation-for-cairomakie/104709 "2023-10-07T21:16:49Z")

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Hello, I want to animate a series of heatmaps and save it to a video but when I try, the heatmap does not stay in the same place and shakes (its position changes slightly for each frame). Below is code for a minimum wor…

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## [The erros of using RAPOSa(https://raposa.usc.es) based on AmplNLWriter](https://discourse.julialang.org/t/the-erros-of-using-raposa-https-raposa-usc-es-based-on-amplnlwriter/104493)

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**Author:** [@wjulia](https://discourse.julialang.org/u/wjulia)\
**Replies:** 6\
**Last updated:** [October 7, 2023, 12:39pm UTC](https://discourse.julialang.org/t/the-erros-of-using-raposa-https-raposa-usc-es-based-on-amplnlwriter/104493 "2023-10-07T12:39:12Z")

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using JuMP, AmplNLWriter m = Model(() → AmplNLWriter.Optimizer(“raposa”)) @variable(m, 1 \<= x \<= 10 ) @variable(m, 0 \<= y \<= 8 ) @NLobjective(m, Min, x^2 + y^2 + x ) @NLconstraint(m, x\*y \>= 1.0 ) optimize!(m) @sho…

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## [(Insanely-) Higher Order Derivatives](https://discourse.julialang.org/t/insanely-higher-order-derivatives/104455)

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**Author:** [@NitinGupta](https://discourse.julialang.org/u/NitinGupta)\
**Replies:** 36\
**Last updated:** [October 6, 2023, 10:29pm UTC](https://discourse.julialang.org/t/insanely-higher-order-derivatives/104455 "2023-10-06T22:29:58Z")

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What’s the recommended way to obtain insanely high order derivatives of a complex valued (terribly complicated) function in Julia? Presently, I’m using TaylorSeries and it works fantastically. However, I need to compute…

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## ["Switching" out the attached \`Optimizer\` of an (empty) model](https://discourse.julialang.org/t/switching-out-the-attached-optimizer-of-an-empty-model/104633)

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**Author:** [@sstroemer](https://discourse.julialang.org/u/sstroemer)\
**Replies:** 9\
**Last updated:** [October 6, 2023, 5:28pm UTC](https://discourse.julialang.org/t/switching-out-the-attached-optimizer-of-an-empty-model/104633 "2023-10-06T17:28:04Z")

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I’m trying to do the following, in order to “parameterize” a model function make\_parametric!(model::JuMP.Model) if !isempty(model) @error "\[core\] Model must be empty when trying to switch to parametric mode"…

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## [Status of ABC-SMC samplers in Julia](https://discourse.julialang.org/t/status-of-abc-smc-samplers-in-julia/88348)

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**Author:** [@fipelle](https://discourse.julialang.org/u/fipelle)\
**Replies:** 10\
**Last updated:** [October 6, 2023, 4:36pm UTC](https://discourse.julialang.org/t/status-of-abc-smc-samplers-in-julia/88348 "2023-10-06T16:36:51Z")

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Hi, I was wondering what is the current status of ABC samplers in Julia. I have seen that GpABC.jl has a few options, but I was wondering if there are alternative packages with a special focus on SMC. I do not have some…

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## [How to make this custom median for color images faster](https://discourse.julialang.org/t/how-to-make-this-custom-median-for-color-images-faster/104651)

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**Author:** [@Rakesh](https://discourse.julialang.org/u/Rakesh)\
**Replies:** 2\
**Last updated:** [October 6, 2023, 3:47pm UTC](https://discourse.julialang.org/t/how-to-make-this-custom-median-for-color-images-faster/104651 "2023-10-06T15:47:00Z")

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I have made custom median filter for color images, but it performs slow and takes high memory compared to OpenCV.medianBlur. Here is code using ImageIO using FileIO using ImageFiltering using ImageCore # using Statistic…

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## [Writing dataframe to arrow format with column metadata](https://discourse.julialang.org/t/writing-dataframe-to-arrow-format-with-column-metadata/104407)

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**Author:** [@alicepiller](https://discourse.julialang.org/u/alicepiller)\
**Replies:** 6\
**Last updated:** [October 6, 2023, 11:33am UTC](https://discourse.julialang.org/t/writing-dataframe-to-arrow-format-with-column-metadata/104407 "2023-10-06T11:33:08Z")

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I’m trying to write a dataframe to an arrow file and include column metadata. The code below runs, but example\_metadata has none of the metadata. using Arrow using DataFrames df = DataFrame(x = \[1, 2, 3\], y = \[4, 5, 6…

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## [Writing Turing.jl model to avoid loops?](https://discourse.julialang.org/t/writing-turing-jl-model-to-avoid-loops/104593)

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**Author:** [@dleather](https://discourse.julialang.org/u/dleather)\
**Replies:** 2\
**Last updated:** [October 6, 2023, 7:39am UTC](https://discourse.julialang.org/t/writing-turing-jl-model-to-avoid-loops/104593 "2023-10-06T07:39:37Z")

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I’m trying to estimate an 2-dimension Multivariate Ornstein-Uhlenbeck process in Turing.jl using the NUTS algorithm. The solution to this model involves the computation of a matrix exponential. As far as I can deduce, t…

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## [Turing's summary statistics - ESS](https://discourse.julialang.org/t/turings-summary-statistics-ess/103537)

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**Author:** [@PrimulaBunce](https://discourse.julialang.org/u/PrimulaBunce)\
**Replies:** 2\
**Last updated:** [October 6, 2023, 7:35am UTC](https://discourse.julialang.org/t/turings-summary-statistics-ess/103537 "2023-10-06T07:35:31Z")

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Hi, I’m new to MCMC, and I’m using the Turing package to implement NUTS. par\_NUTS = sample(model, NUTS(1000, 0.65), MCMCThreads(), 1000, 3) I’m trying to figure out what the Effective Sample Size (ESS) values returned…

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## [Hot to maintain equal plot sizes of subplot when using e.g. \`legend=:outertop\`?](https://discourse.julialang.org/t/hot-to-maintain-equal-plot-sizes-of-subplot-when-using-e-g-legend-outertop/104637)

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**Author:** [@Torkel](https://discourse.julialang.org/u/Torkel)\
**Replies:** 0\
**Last updated:** [October 5, 2023, 11:48pm UTC](https://discourse.julialang.org/t/hot-to-maintain-equal-plot-sizes-of-subplot-when-using-e-g-legend-outertop/104637 "2023-10-05T23:48:29Z")

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MWE: using Plots p1 = plot(x-\>x^2, label = "my curve") plot(x-\>x^1, label = "A curve") plot!(x-\>x^1, label = "Curve 1") plot!(x-\>x^2, label = "Curve 2") plot!(x-\>x^3, label = "Curve 3") plot!(x-\>x^4, label = "Curve 4") …

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## [About Start Values in JuMP - MOA](https://discourse.julialang.org/t/about-start-values-in-jump-moa/104500)

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**Author:** [@rodolforbcoutinho](https://discourse.julialang.org/u/rodolforbcoutinho)\
**Replies:** 6\
**Last updated:** [October 5, 2023, 1:39pm UTC](https://discourse.julialang.org/t/about-start-values-in-jump-moa/104500 "2023-10-05T13:39:54Z")

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Hello to all! I have a doubt about using start values in variables. My hypothesis was that could speed up the execution time if I provide most of the values in variable vector already in optimum position. In my proble…

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## [Inline labeling on line plot (using Plots.jl)](https://discourse.julialang.org/t/inline-labeling-on-line-plot-using-plots-jl/104250)

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**Author:** [@Brent](https://discourse.julialang.org/u/Brent)\
**Replies:** 2\
**Last updated:** [October 5, 2023, 10:27am UTC](https://discourse.julialang.org/t/inline-labeling-on-line-plot-using-plots-jl/104250 "2023-10-05T10:27:11Z")

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Is there a way to do inline labeling (or direct labeling) of lines in a line plot using the Plots.jl package? I’m looking for something similar to the package matplotlib-label-lines for Python. Some examples from the doc…

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## [Easy way to plot a circle given as a vector of vectors (pointwise) as line plot?](https://discourse.julialang.org/t/easy-way-to-plot-a-circle-given-as-a-vector-of-vectors-pointwise-as-line-plot/104574)

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**Author:** [@homocomputeris](https://discourse.julialang.org/u/homocomputeris)\
**Replies:** 15\
**Last updated:** [October 5, 2023, 9:30am UTC](https://discourse.julialang.org/t/easy-way-to-plot-a-circle-given-as-a-vector-of-vectors-pointwise-as-line-plot/104574 "2023-10-05T09:30:15Z")

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Is there an easier way to plot a shape (in geometric sense, not Plots.jl’s) given as a vector of points (i.e. 2D-vectors)? using Plots # approximately a circle vector\_of\_points = \[\[0.708441362115303, 1.413585198669223\]…

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## [Sampling without replacement](https://discourse.julialang.org/t/sampling-without-replacement/1073)

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**Author:** [@SPV](https://discourse.julialang.org/u/SPV)\
**Replies:** 9\
**Last updated:** [October 5, 2023, 5:54am UTC](https://discourse.julialang.org/t/sampling-without-replacement/1073 "2023-10-05T05:54:32Z")

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rand(1:20, 3) gives three random integers in \[1:20\] with replacement. I see there are some threads on github on this issue, but I am not sure what is the recommended way with Julia 0.5 to sample without replacement.

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## [Using SciMLOperators in LinearSolve](https://discourse.julialang.org/t/using-scimloperators-in-linearsolve/104596)

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**Author:** [@j35](https://discourse.julialang.org/u/j35)\
**Replies:** 0\
**Last updated:** [October 4, 2023, 11:52pm UTC](https://discourse.julialang.org/t/using-scimloperators-in-linearsolve/104596 "2023-10-04T23:52:32Z")

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I’m trying to use FunctionOperators from SciMLOperators, to solve a linear problem using matrix free method. But I’m getting wrong result. What am I doing wrong here? Thanks in advance. Here is the MWE. using SparseArr…

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## [How to optimize a neural network with a "traditional" optimizer?](https://discourse.julialang.org/t/how-to-optimize-a-neural-network-with-a-traditional-optimizer/104580)

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**Author:** [@ForceBru](https://discourse.julialang.org/u/ForceBru)\
**Replies:** 1\
**Last updated:** [October 4, 2023, 6:50pm UTC](https://discourse.julialang.org/t/how-to-optimize-a-neural-network-with-a-traditional-optimizer/104580 "2023-10-04T18:50:44Z")

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Nowadays neural networks are represented as trees with parameters as leaves. This is how PyTorch, JAX and Julia’s Flux do it. It doesn’t let one update all parameters at once like x = x - lr \* grad(objective)(x), so libr…

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## [Output automatic time steps taken by solvers while specifying \`saveat\`](https://discourse.julialang.org/t/output-automatic-time-steps-taken-by-solvers-while-specifying-saveat/104578)

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**Author:** [@yhchang96](https://discourse.julialang.org/u/yhchang96)\
**Replies:** 1\
**Last updated:** [October 4, 2023, 6:26pm UTC](https://discourse.julialang.org/t/output-automatic-time-steps-taken-by-solvers-while-specifying-saveat/104578 "2023-10-04T18:26:06Z")

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Many solvers in OrdinaryDiffEq.jl for solving stiff ODEs use automatic time-stepping. From what I understand, if I specify saveat, then sol.t is the time steps I specify in saveat, and if I leave saveat untouched, then s…

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