# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=463

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**Page:** 464

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## [Why Atom try to reinstall Matplotlib using Conda so frequently?](https://discourse.julialang.org/t/why-atom-try-to-reinstall-matplotlib-using-conda-so-frequently/34576)

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**Author:** [@josimar](https://discourse.julialang.org/u/josimar)\
**Replies:** 0\
**Last updated:** [February 13, 2020, 2:33pm UTC](https://discourse.julialang.org/t/why-atom-try-to-reinstall-matplotlib-using-conda-so-frequently/34576 "2020-02-13T14:33:17Z")

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It often happens that Atom tries to reinstall matplotlib using Conda. However, this is already installed and I don’t understand why it gets stuck on this. Below I copy the exact code and message that I get. Note: this …

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## [Making a surface from scattered data](https://discourse.julialang.org/t/making-a-surface-from-scattered-data/27622)

<div class="topic-metadata">

**Author:** [@Noel\_Araujo](https://discourse.julialang.org/u/Noel_Araujo)\
**Replies:** 4\
**Last updated:** [February 13, 2020, 2:29pm UTC](https://discourse.julialang.org/t/making-a-surface-from-scattered-data/27622 "2020-02-13T14:29:12Z")

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I would to transform scattered data into a surface. Google told me that is I could do it in Matlab\[1,2\] or Python \[3\] using Delaunay triangulation. But I cannot find a similar example in Julia with VoronoiDelaunay.jl an…

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## [MethodError: no method matching Gurobi.Env(::Ptr{Nothing})](https://discourse.julialang.org/t/methoderror-no-method-matching-gurobi-env-ptr-nothing/34555)

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**Author:** [@Ken\_Lin](https://discourse.julialang.org/u/Ken_Lin)\
**Replies:** 1\
**Last updated:** [February 13, 2020, 8:37am UTC](https://discourse.julialang.org/t/methoderror-no-method-matching-gurobi-env-ptr-nothing/34555 "2020-02-13T08:37:08Z")

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Hello, I tried setting the Gurobi parameter “NonConvex” to 2 and I got the following error: “MethodError: no method matching Gurobi.Env(::Ptr{Nothing})”. My Julia Gurobi version is v0.7.5 and I am using Julia 1.3.1. I g…

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## [Solving large(?) problem with Convex.jl and SCS](https://discourse.julialang.org/t/solving-large-problem-with-convex-jl-and-scs/30159)

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**Author:** [@riccardomurri](https://discourse.julialang.org/u/riccardomurri)\
**Replies:** 13\
**Last updated:** [February 13, 2020, 6:37am UTC](https://discourse.julialang.org/t/solving-large-problem-with-convex-jl-and-scs/30159 "2020-02-13T06:37:33Z")

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Hello! I am trying to port some MATLAB code (which uses YALMIP to call into SCS) over to Julia (using Convex.jl and SCS.jl for the purpose). The code builds sparse matrices A, C, D, sparse vector b and tries to solve…

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## [JuliaGeo talk at FOSS4G 2019](https://discourse.julialang.org/t/juliageo-talk-at-foss4g-2019/28425)

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**Author:** [@evetion](https://discourse.julialang.org/u/evetion)\
**Replies:** 9\
**Last updated:** [February 12, 2020, 11:49pm UTC](https://discourse.julialang.org/t/juliageo-talk-at-foss4g-2019/28425 "2020-02-12T23:49:47Z")

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Hi all, @visr and me have presented the JuliaGeo ecosystem at the FOSS4G 2019 conference in Bucharest. You can find the video here and the slides (on NextJournal) here. This was the first talk about Julia at FOSS4G as f…

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## [For Knet.jl connoisseurs : problem with WTYPE error](https://discourse.julialang.org/t/for-knet-jl-connoisseurs-problem-with-wtype-error/34523)

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**Author:** [@Johncowk](https://discourse.julialang.org/u/Johncowk)\
**Replies:** 0\
**Last updated:** [February 12, 2020, 3:46pm UTC](https://discourse.julialang.org/t/for-knet-jl-connoisseurs-problem-with-wtype-error/34523 "2020-02-12T15:46:19Z")

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I am trying to build a RNN with self-attention mechanism using knet (maybe I should have sticked to python …) and after fixing all sorts of puzzling error I am faced with the following one : AssertionError: r.c == nothi…

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## [StatsBase.jl sample size \> 31 throws error](https://discourse.julialang.org/t/statsbase-jl-sample-size-31-throws-error/34484)

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**Author:** [@mthelm85](https://discourse.julialang.org/u/mthelm85)\
**Replies:** 3\
**Last updated:** [February 12, 2020, 12:52pm UTC](https://discourse.julialang.org/t/statsbase-jl-sample-size-31-throws-error/34484 "2020-02-12T12:52:16Z")

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I’m running into an issue that I’m hoping someone can help me understand. I have a 1308 x 22 DataFrame that I’m trying to sample from with StatsBase. All is well and fine as long as n \<= 31. The code looks like this: j…

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## [How can I get the CS decomposition of a matrix?](https://discourse.julialang.org/t/how-can-i-get-the-cs-decomposition-of-a-matrix/34499)

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**Author:** [@Deniz](https://discourse.julialang.org/u/Deniz)\
**Replies:** 6\
**Last updated:** [February 12, 2020, 10:16am UTC](https://discourse.julialang.org/t/how-can-i-get-the-cs-decomposition-of-a-matrix/34499 "2020-02-12T10:16:16Z")

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There seems to be no function in any well-known Julia library to obtain the CS decomposition of a matrix. There is a function CUNCSD in LAPACK, but it is not available in Julia by default. Maybe I can call that function…

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## [\[ANN\] Tables.jl 1.0 Release](https://discourse.julialang.org/t/ann-tables-jl-1-0-release/34505)

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**Author:** [@quinnj](https://discourse.julialang.org/u/quinnj)\
**Replies:** 0\
**Last updated:** [February 12, 2020, 7:32am UTC](https://discourse.julialang.org/t/ann-tables-jl-1-0-release/34505 "2020-02-12T07:32:47Z")

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Hello all, A new 1.0 release was just registered in the General registry for the Tables.jl package. The API has matured well over the last 1.5 years (since 2018 JuliaCon hackathon!), and we felt like it was time for an…

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## [Fitting a circle/ellipse over an image](https://discourse.julialang.org/t/fitting-a-circle-ellipse-over-an-image/34143)

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**Author:** [@razvangheorghe](https://discourse.julialang.org/u/razvangheorghe)\
**Replies:** 15\
**Last updated:** [February 11, 2020, 7:48pm UTC](https://discourse.julialang.org/t/fitting-a-circle-ellipse-over-an-image/34143 "2020-02-11T19:48:03Z")

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Hello, It would be very useful if I could fit a circle/ellipse over a set of density plots. The images are very noisy, but for most of them, you can vaguely make up the shape of an ellipse. Here’s an example: What …

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## [Defining parameters in CPLEX](https://discourse.julialang.org/t/defining-parameters-in-cplex/34476)

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**Author:** [@angeloaliano1](https://discourse.julialang.org/u/angeloaliano1)\
**Replies:** 3\
**Last updated:** [February 11, 2020, 6:51pm UTC](https://discourse.julialang.org/t/defining-parameters-in-cplex/34476 "2020-02-11T18:51:42Z")

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Hello dears users, I want to define the limit of CPU time, gap etc for CPLEX in a given integer problem. In JuMP version v0.19 I was used to define: model=Model(with\_optimizer(CPLEX.Optimizer,CPX\_PARAM\_TILIM=10800,CPX\_…

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## [Obtaining Gap in integer programming](https://discourse.julialang.org/t/obtaining-gap-in-integer-programming/34377)

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**Author:** [@angeloaliano1](https://discourse.julialang.org/u/angeloaliano1)\
**Replies:** 9\
**Last updated:** [February 11, 2020, 2:58pm UTC](https://discourse.julialang.org/t/obtaining-gap-in-integer-programming/34377 "2020-02-11T14:58:30Z")

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Hello dear, I have an interest to obtain the relative Gap in a optimization integer problem. I have consulted Reference · MathOptInterface and when I give the command RelativeGap(), nothing happens. The CPLEX and Juli…

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## [Linear programming with Jump](https://discourse.julialang.org/t/linear-programming-with-jump/34192)

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**Author:** [@bandaya](https://discourse.julialang.org/u/bandaya)\
**Replies:** 8\
**Last updated:** [February 10, 2020, 10:10pm UTC](https://discourse.julialang.org/t/linear-programming-with-jump/34192 "2020-02-10T22:10:50Z")

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I am trying to write a linear programming problem problem in JuMP but I am getting error messages. I have given my code below, and I believe the issue is in definition of the constraint. Please can someone help to fix t…

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## [Problems in obtaing of the Relative Gap](https://discourse.julialang.org/t/problems-in-obtaing-of-the-relative-gap/34433)

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**Author:** [@angeloaliano1](https://discourse.julialang.org/u/angeloaliano1)\
**Replies:** 1\
**Last updated:** [February 10, 2020, 9:47pm UTC](https://discourse.julialang.org/t/problems-in-obtaing-of-the-relative-gap/34433 "2020-02-10T21:47:14Z")

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I have the following simple problem: using JuMP using CPLEX m = Model(with\_optimizer(CPLEX.Optimizer)) c = \[ 1; 2; 5\] A = \[-1 1 3; 1 3 -7\] b = \[-5; 10\] @variable(m, x\[1:3\] \>= 0) @objective(m, Max, sum( c\[i\]\*x…

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## [How to make a callback including variables in definition](https://discourse.julialang.org/t/how-to-make-a-callback-including-variables-in-definition/34431)

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**Author:** [@xixit](https://discourse.julialang.org/u/xixit)\
**Replies:** 0\
**Last updated:** [February 10, 2020, 7:12pm UTC](https://discourse.julialang.org/t/how-to-make-a-callback-including-variables-in-definition/34431 "2020-02-10T19:12:33Z")

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Hi, I want to make a callback function set for my differential equation. The problem is I want to make it flexible so in future I can change any desireable callback function without changing the code. It’s a simple contr…

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## [How can I optimize recurrent networks in Flux?](https://discourse.julialang.org/t/how-can-i-optimize-recurrent-networks-in-flux/34425)

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**Author:** [@jmeeks29ig](https://discourse.julialang.org/u/jmeeks29ig)\
**Replies:** 0\
**Last updated:** [February 10, 2020, 5:15pm UTC](https://discourse.julialang.org/t/how-can-i-optimize-recurrent-networks-in-flux/34425 "2020-02-10T17:15:45Z")

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Hi, I posted a question in stackoverflow (optimization - How can I optimize a recurrent network in Julia with Flux? - Stack Overflow) regarding the performance of Flux in using a recurrent neural network. I have been ge…

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## [CUDAnative.jl failed to initialize](https://discourse.julialang.org/t/cudanative-jl-failed-to-initialize/34342)

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**Author:** [@Ferran\_Mazzanti](https://discourse.julialang.org/u/Ferran_Mazzanti)\
**Replies:** 11\
**Last updated:** [February 10, 2020, 3:54pm UTC](https://discourse.julialang.org/t/cudanative-jl-failed-to-initialize/34342 "2020-02-10T15:54:51Z")

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Hi, I’ve been using CUDAnative, CUDAdrv and CuArrays extensively in my ubuntu box for few months now, but somehow after an update of julia packages (which included these) I can no longer use them using CUDAnative \> \[ I…

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## [Training dataset and reporting MSE](https://discourse.julialang.org/t/training-dataset-and-reporting-mse/34391)

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**Author:** [@Praise](https://discourse.julialang.org/u/Praise)\
**Replies:** 6\
**Last updated:** [February 10, 2020, 2:49pm UTC](https://discourse.julialang.org/t/training-dataset-and-reporting-mse/34391 "2020-02-10T14:49:16Z")

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Hello, I am trying to train dataset using linear regression in julia and then I have to calculate the MSE of the given test dataset. I was wondering what are the best packages to use, and an example of how to do this wit…

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## [Lazyconstraint not defined using GLPK solver callbacks](https://discourse.julialang.org/t/lazyconstraint-not-defined-using-glpk-solver-callbacks/34012)

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**Author:** [@Espenol](https://discourse.julialang.org/u/Espenol)\
**Replies:** 4\
**Last updated:** [February 10, 2020, 1:51pm UTC](https://discourse.julialang.org/t/lazyconstraint-not-defined-using-glpk-solver-callbacks/34012 "2020-02-10T13:51:22Z")

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Hello! Sorry about the newb question, but I have an issue setting lazy constraint. I follow the example here but don’t have access to licensed solvers so I use the GLPK solver instead of the Gurobi solver by applying th…

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## [Julia Flux Right Version](https://discourse.julialang.org/t/julia-flux-right-version/34303)

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**Author:** [@Owolf](https://discourse.julialang.org/u/Owolf)\
**Replies:** 3\
**Last updated:** [February 10, 2020, 11:10am UTC](https://discourse.julialang.org/t/julia-flux-right-version/34303 "2020-02-10T11:10:12Z")

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Hello Everybody, I am new in Julia and Flux. I went through model-zoo and it seems as pretty nice example. However as far I had no luck to make it work. After hours of googling and going through non-consistent informati…

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## [Julia plots error with errorbars in v0.29.0](https://discourse.julialang.org/t/julia-plots-error-with-errorbars-in-v0-29-0/34404)

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**Author:** [@transarcus](https://discourse.julialang.org/u/transarcus)\
**Replies:** 2\
**Last updated:** [February 10, 2020, 10:51am UTC](https://discourse.julialang.org/t/julia-plots-error-with-errorbars-in-v0-29-0/34404 "2020-02-10T10:51:42Z")

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I have been quite happily plotting graphs with errorbars in julia, but today it started to give me an error. I have tried searching for this issue but haven’t been able to find anything. using Plots plot(\[1,2,3,4\],\[1,2,…

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## [In Zygote, why (model)-\>... in gradient](https://discourse.julialang.org/t/in-zygote-why-model-in-gradient/34367)

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**Author:** [@jaynick](https://discourse.julialang.org/u/jaynick)\
**Replies:** 4\
**Last updated:** [February 10, 2020, 6:16am UTC](https://discourse.julialang.org/t/in-zygote-why-model-in-gradient/34367 "2020-02-10T06:16:23Z")

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In this (helpful!) post, https://kiranshila.com/index.php/2020/02/04/teaching-myself-machine-learning-with-julia-part-1/ The (zygote) gradient call is g = gradient(model -\> mse(model.(x),y), model) I tried instead…

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## [Innocent looking optimization of the forward pass causes performance cliff in gradient calculation with Zygote.jl v0.4.7](https://discourse.julialang.org/t/innocent-looking-optimization-of-the-forward-pass-causes-performance-cliff-in-gradient-calculation-with-zygote-jl-v0-4-7/34188)

<div class="topic-metadata">

**Author:** [@Azamat](https://discourse.julialang.org/u/Azamat)\
**Replies:** 5\
**Last updated:** [February 5, 2020, 3:50pm UTC](https://discourse.julialang.org/t/innocent-looking-optimization-of-the-forward-pass-causes-performance-cliff-in-gradient-calculation-with-zygote-jl-v0-4-7/34188 "2020-02-05T15:50:17Z")

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Consider the following code example: using LinearAlgebra using Flux using BenchmarkTools function diagmatmul(m, xs) ys = m.(xs) zs = diag.((first(ys)',) .\* ys) return sum(sum(zs)) end function colwise(m, x…

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## [Gradient of the einsum not working with CuArrays, when it's output is assigned to the field of a mutable struct](https://discourse.julialang.org/t/gradient-of-the-einsum-not-working-with-cuarrays-when-its-output-is-assigned-to-the-field-of-a-mutable-struct/34396)

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**Author:** [@Azamat](https://discourse.julialang.org/u/Azamat)\
**Replies:** 0\
**Last updated:** [February 10, 2020, 3:00am UTC](https://discourse.julialang.org/t/gradient-of-the-einsum-not-working-with-cuarrays-when-its-output-is-assigned-to-the-field-of-a-mutable-struct/34396 "2020-02-10T03:00:46Z")

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I’m getting a strange error when using OMEinsum, CuArrays and Zygote together. Here is the MRE: using CuArrays using Zygote using OMEinsum mutable struct S{T} c::T end function f(α, s, H) @ein s.c\[d,b\] := α\[t,b\]…

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## [Calling Mosek on Convex.jl](https://discourse.julialang.org/t/calling-mosek-on-convex-jl/34378)

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**Author:** [@martincornejo](https://discourse.julialang.org/u/martincornejo)\
**Replies:** 3\
**Last updated:** [February 9, 2020, 4:09pm UTC](https://discourse.julialang.org/t/calling-mosek-on-convex-jl/34378 "2020-02-09T16:09:09Z")

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I get the following error when trying to solve an SDP problem with Mosek using Convex, Mosek ... (problem formulation) solve!(problem, MosekSolver()) ERROR: UndefVarError: MosekSolver not defined

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## [How to make Optim's optimize work for scalars](https://discourse.julialang.org/t/how-to-make-optims-optimize-work-for-scalars/34343)

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**Author:** [@compleat](https://discourse.julialang.org/u/compleat)\
**Replies:** 3\
**Last updated:** [February 8, 2020, 1:16pm UTC](https://discourse.julialang.org/t/how-to-make-optims-optimize-work-for-scalars/34343 "2020-02-08T13:16:30Z")

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In the interest of user-friendliness, would anyone know a way to overload ‘optimize’ to work conveniently for scalar input without crashing? \[please note I am not asking for opinions as to how good/bad an idea it would …

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## [About NaN, 0/0 and false](https://discourse.julialang.org/t/about-nan-0-0-and-false/34272)

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**Author:** [@aerdely](https://discourse.julialang.org/u/aerdely)\
**Replies:** 21\
**Last updated:** [February 8, 2020, 8:12am UTC](https://discourse.julialang.org/t/about-nan-0-0-and-false/34272 "2020-02-08T08:12:57Z")

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Why… NaN\*(0/0)\*false gives 0.0, (0/0)\*NaN\*false gives -0.0, and: false\*(0/0)\*NaN false\*NaN\*(0/0) NaN\*false\*(0/0) (0/0)\*false\*NaN all give NaN? :thinking: Because changing false by true we get always the same …

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## [Kernel Polynomial Method](https://discourse.julialang.org/t/kernel-polynomial-method/34240)

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**Author:** [@mgaffar](https://discourse.julialang.org/u/mgaffar)\
**Replies:** 3\
**Last updated:** [February 7, 2020, 6:56pm UTC](https://discourse.julialang.org/t/kernel-polynomial-method/34240 "2020-02-07T18:56:57Z")

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Is there any packages that already implement KPM?

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## [Are SharedArrays bypassing cache?](https://discourse.julialang.org/t/are-sharedarrays-bypassing-cache/34269)

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**Author:** [@j-fu](https://discourse.julialang.org/u/j-fu)\
**Replies:** 4\
**Last updated:** [February 7, 2020, 6:51pm UTC](https://discourse.julialang.org/t/are-sharedarrays-bypassing-cache/34269 "2020-02-07T18:51:58Z")

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Hi, I am testing parallel computations based on multithreading/multiprocessing. Aimed at iterative solvers for PDEs I am interested in large loops. An interesting benchmark in this respect is the “Schönauer vector triad…

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## [How can I train a simple model to understand the relation of math addition? \[Flux\]](https://discourse.julialang.org/t/how-can-i-train-a-simple-model-to-understand-the-relation-of-math-addition-flux/34294)

<div class="topic-metadata">

**Author:** [@TheOnlyArtz](https://discourse.julialang.org/u/TheOnlyArtz)\
**Replies:** 5\
**Last updated:** [February 7, 2020, 2:07pm UTC](https://discourse.julialang.org/t/how-can-i-train-a-simple-model-to-understand-the-relation-of-math-addition-flux/34294 "2020-02-07T14:07:27Z")

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So as the title suggests, I want to get started with Flux and I can’t really understand that much from the docs, I want to train a simple model which will take 2 numbers in the input layer and output a single number (the…

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