# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?page=289

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**Page:** 290

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## [Spectral Methods in Julia](https://discourse.julialang.org/t/spectral-methods-in-julia/79506)

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**Author:** [@Veenty](https://discourse.julialang.org/u/Veenty)\
**Replies:** 4\
**Last updated:** [April 15, 2022, 8:54am UTC](https://discourse.julialang.org/t/spectral-methods-in-julia/79506 "2022-04-15T08:54:28Z")

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I want to solve Poisson equation in the ellipse via (pseudo)-spectral methods. I was thinking of using Dedalus via Pycall or something like that. But are there any good alternatives in Julia? Most things that I’ve found…

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## [Strange multithreaded behaviour on ARM Ampere A1 (Oracle Cloud)](https://discourse.julialang.org/t/strange-multithreaded-behaviour-on-arm-ampere-a1-oracle-cloud/79490)

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**Author:** [@Dandan](https://discourse.julialang.org/u/Dandan)\
**Replies:** 10\
**Last updated:** [April 14, 2022, 6:56pm UTC](https://discourse.julialang.org/t/strange-multithreaded-behaviour-on-arm-ampere-a1-oracle-cloud/79490 "2022-04-14T18:56:17Z")

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I’ve tried to run the following simple benchmark in Oracle Cloud VM on an instance with 4 vCPU of ARM Ampere A1 and 24GB ram: using LinearAlgebra function foo() Threads.@threads for i in 1:10000 H = rand(100, 100) +…

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## [How to pass 'ADNLPModels.ReverseDiffAD() as the adbackend keyword argument to the ADNLPModel or ADNLSModel constructor.'](https://discourse.julialang.org/t/how-to-pass-adnlpmodels-reversediffad-as-the-adbackend-keyword-argument-to-the-adnlpmodel-or-adnlsmodel-constructor/79442)

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**Author:** [@Gummala\_Navneeth](https://discourse.julialang.org/u/Gummala_Navneeth)\
**Replies:** 10\
**Last updated:** [April 14, 2022, 8:49pm UTC](https://discourse.julialang.org/t/how-to-pass-adnlpmodels-reversediffad-as-the-adbackend-keyword-argument-to-the-adnlpmodel-or-adnlsmodel-constructor/79442 "2022-04-14T20:49:42Z")

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Hi all, I’m trying to minimize a function which has constraint as nonlinear vector function. input of constraint function is vector and output of constraint function is a vector of large size ( more than 500 elements ) …

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## [OOM when using Flux and loops](https://discourse.julialang.org/t/oom-when-using-flux-and-loops/79468)

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**Author:** [@Fabrice\_Rosay](https://discourse.julialang.org/u/Fabrice_Rosay)\
**Replies:** 4\
**Last updated:** [April 14, 2022, 1:37pm UTC](https://discourse.julialang.org/t/oom-when-using-flux-and-loops/79468 "2022-04-14T13:37:19Z")

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The following code works with actor a residual network of depth 5 and 64 filters if n=1000 (using Flux) But if the lines calling GC are commented, it fails with OOM. Using CUDA 3.9 and Nvidia Driver Version: 510.47.03 …

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## [How to model a chemical reaction network with changing parameters? (Catalyst.jl)](https://discourse.julialang.org/t/how-to-model-a-chemical-reaction-network-with-changing-parameters-catalyst-jl/79489)

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**Author:** [@govissers](https://discourse.julialang.org/u/govissers)\
**Replies:** 5\
**Last updated:** [April 14, 2022, 5:38pm UTC](https://discourse.julialang.org/t/how-to-model-a-chemical-reaction-network-with-changing-parameters-catalyst-jl/79489 "2022-04-14T17:38:12Z")

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Hello, I am hoping to model a chemical reaction network within a cell, where an organism may change the rate of a reaction given an external stimulus at time t. Is it possible to model a CRN wherea reaction constant, sp…

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## [Solve strain for given stress in von Mises plasticity](https://discourse.julialang.org/t/solve-strain-for-given-stress-in-von-mises-plasticity/79501)

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**Author:** [@FrootLoops](https://discourse.julialang.org/u/FrootLoops)\
**Replies:** 0\
**Last updated:** [April 14, 2022, 5:23pm UTC](https://discourse.julialang.org/t/solve-strain-for-given-stress-in-von-mises-plasticity/79501 "2022-04-14T17:23:46Z")

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Hi, I am trying to caculate for a given stress the corresponding strain in the Von Mises plasticity example. I know that this results in a non-linear equation. Not notice I have the following equations: σᵗ = C ⊡ (ϵ - ϵ…

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## [Transferring \*all\* plotted elements (and their links to observables) between Axis](https://discourse.julialang.org/t/transferring-all-plotted-elements-and-their-links-to-observables-between-axis/79492)

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**Author:** [@Datseris](https://discourse.julialang.org/u/Datseris)\
**Replies:** 2\
**Last updated:** [April 14, 2022, 2:26pm UTC](https://discourse.julialang.org/t/transferring-all-plotted-elements-and-their-links-to-observables-between-axis/79492 "2022-04-14T14:26:02Z")

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I admit, I’m not particularly optimistic whether this is possible, but here goes. I have a fig, ax, which is an Axis/Axis3 plotted on a Figure. On this axis many things are plotted, and many of the plotted things are ob…

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## [Apply a column of anonymous functions for each column in a column subset](https://discourse.julialang.org/t/apply-a-column-of-anonymous-functions-for-each-column-in-a-column-subset/79402)

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**Author:** [@babaq](https://discourse.julialang.org/u/babaq)\
**Replies:** 11\
**Last updated:** [April 14, 2022, 1:02pm UTC](https://discourse.julialang.org/t/apply-a-column-of-anonymous-functions-for-each-column-in-a-column-subset/79402 "2022-04-14T13:02:50Z")

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Hi, Suppose we have a DataFrame like this: df = DataFrame(name='a':'c',x1=1:3,x2=\[\[1,2\],\[3,4\],\[5,6\]\],xfun=\[x-\>x.-1,x-\>x.^2,x-\>x.^3\]) I want to transform column x1 and x2 in df by apply each fun in xfun for the corresp…

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## [Valid values for attributes: is there a list or a way to look them up?](https://discourse.julialang.org/t/valid-values-for-attributes-is-there-a-list-or-a-way-to-look-them-up/79386)

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**Author:** [@weltenbummler](https://discourse.julialang.org/u/weltenbummler)\
**Replies:** 2\
**Last updated:** [April 14, 2022, 10:40am UTC](https://discourse.julialang.org/t/valid-values-for-attributes-is-there-a-list-or-a-way-to-look-them-up/79386 "2022-04-14T10:40:23Z")

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Hello, In makie, I can look up a list with attributes by e.g. writing fig = Figure() ax = Axis(fig\[1,1\]) ax.attributes It lists the attributes and shows the current settings. However, how can I find out the valid valu…

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## [Time varying input in ReachabilityAnalysis](https://discourse.julialang.org/t/time-varying-input-in-reachabilityanalysis/78419)

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**Author:** [@martincornejo](https://discourse.julialang.org/u/martincornejo)\
**Replies:** 2\
**Last updated:** [April 14, 2022, 10:10am UTC](https://discourse.julialang.org/t/time-varying-input-in-reachabilityanalysis/78419 "2022-04-14T10:10:09Z")

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Let’s take the following example taken from ReachabilityAnalysis’s documentation: https://juliareach.github.io/ReachabilityAnalysis.jl/dev/models/TransmissionLine/#Transmission-line-circuit For the input, it takes the …

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## [PlotlyJS 3d scatter plot does not respect zmin and zmax](https://discourse.julialang.org/t/plotlyjs-3d-scatter-plot-does-not-respect-zmin-and-zmax/79475)

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**Author:** [@Jae-Mo\_Lihm](https://discourse.julialang.org/u/Jae-Mo_Lihm)\
**Replies:** 2\
**Last updated:** [April 14, 2022, 9:15am UTC](https://discourse.julialang.org/t/plotlyjs-3d-scatter-plot-does-not-respect-zmin-and-zmax/79475 "2022-04-14T09:15:38Z")

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How can I fix zmin and zmax in the colorscale? using PlotlyJS PlotlyJS.plot(PlotlyJS.scatter( x=\[0, 1\], y=\[0, 1\], mode="markers", marker=attr( size = 10, color = \[-2, 1\], showscale =…

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## [PyPlot for PythonCall](https://discourse.julialang.org/t/pyplot-for-pythoncall/79407)

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**Author:** [@goerz](https://discourse.julialang.org/u/goerz)\
**Replies:** 3\
**Last updated:** [April 14, 2022, 2:27am UTC](https://discourse.julialang.org/t/pyplot-for-pythoncall/79407 "2022-04-14T02:27:20Z")

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The PyPlot backend for Plots.jl only works with PyCall, right? How hard would it be to make work with PythonCall instead (so I don’t even have to have PyCall installed). I’d very much appreciate the full environment isol…

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## [Makie Unfilled Polygons](https://discourse.julialang.org/t/makie-unfilled-polygons/79440)

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**Author:** [@LaurentPlagne](https://discourse.julialang.org/u/LaurentPlagne)\
**Replies:** 4\
**Last updated:** [April 13, 2022, 9:10pm UTC](https://discourse.julialang.org/t/makie-unfilled-polygons/79440 "2022-04-13T21:10:17Z")

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Hi, what is the syntax to plot unfilled/empty polygons (via Makie.poly!) ?

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## [A problem with JuMP variable defined](https://discourse.julialang.org/t/a-problem-with-jump-variable-defined/79365)

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**Author:** [@mahon](https://discourse.julialang.org/u/mahon)\
**Replies:** 2\
**Last updated:** [April 13, 2022, 6:06pm UTC](https://discourse.julialang.org/t/a-problem-with-jump-variable-defined/79365 "2022-04-13T18:06:46Z")

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i want constraint my variable Pg , how can i do?

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## [Distributions.jl: is it possible to define a Normal+Dirac mixture distribution?](https://discourse.julialang.org/t/distributions-jl-is-it-possible-to-define-a-normal-dirac-mixture-distribution/79429)

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**Author:** [@Vincent\_Picaud](https://discourse.julialang.org/u/Vincent_Picaud)\
**Replies:** 6\
**Last updated:** [April 13, 2022, 5:04pm UTC](https://discourse.julialang.org/t/distributions-jl-is-it-possible-to-define-a-normal-dirac-mixture-distribution/79429 "2022-04-13T17:04:11Z")

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I want to manipulate a distribution mixture of the form \\pi\\delta\_{x\_0}+(1-\\pi)\\mathcal{N}(\\mu,\\sigma) I have checked that I can create a mixture of Normal & Cauchy, by example: julia\> using Disributions.jl julia\> M…

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## [Defining Non Linear Vector Constraints in JuMP](https://discourse.julialang.org/t/defining-non-linear-vector-constraints-in-jump/4742)

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**Author:** [@acauligi](https://discourse.julialang.org/u/acauligi)\
**Replies:** 5\
**Last updated:** [April 13, 2022, 3:49pm UTC](https://discourse.julialang.org/t/defining-non-linear-vector-constraints-in-jump/4742 "2022-04-13T15:49:54Z")

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I’m trying to implement pseudospectral methods using JuMP & Ipopt. The state is n-dimensional and control m-dimensional and the values are evaluated at N+1 collocation points; in this particular problem, n=3, m=3, and N …

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## [JuMP problem get conflicting constraints when using small values](https://discourse.julialang.org/t/jump-problem-get-conflicting-constraints-when-using-small-values/79425)

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**Author:** [@this\_josh](https://discourse.julialang.org/u/this_josh)\
**Replies:** 4\
**Last updated:** [April 13, 2022, 2:04pm UTC](https://discourse.julialang.org/t/jump-problem-get-conflicting-constraints-when-using-small-values/79425 "2022-04-13T14:04:04Z")

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In JuMP I’m having problems getting conflicting equality constraints when using small values using JuMP using Gurobi model = Model(Gurobi.Optimizer) @variable(model, x) a = 5e-5 b = 3e-3 @constraint(model, c1, x == 0)…

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## [Broadcasting error diffeqflux](https://discourse.julialang.org/t/broadcasting-error-diffeqflux/79417)

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**Author:** [@YitaoCai](https://discourse.julialang.org/u/YitaoCai)\
**Replies:** 4\
**Last updated:** [April 13, 2022, 9:34am UTC](https://discourse.julialang.org/t/broadcasting-error-diffeqflux/79417 "2022-04-13T09:34:21Z")

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Built a model according to the augmented Neural ODE tutorial as follows: @with\_kw struct Args η = 1e-3 # learning rate λ = 0.01f0 # regularization paramater batch\_size = 64 …

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## [Lots of messages printed out when I evaluate the model using MLJ](https://discourse.julialang.org/t/lots-of-messages-printed-out-when-i-evaluate-the-model-using-mlj/79415)

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**Author:** [@Sijun](https://discourse.julialang.org/u/Sijun)\
**Replies:** 5\
**Last updated:** [April 13, 2022, 5:23am UTC](https://discourse.julialang.org/t/lots-of-messages-printed-out-when-i-evaluate-the-model-using-mlj/79415 "2022-04-13T05:23:36Z")

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I see lots of messages printed out when I evaluate the model: There are "error"s in the printed messeges. Are they really errors? how critical is it? or can I just ignore them? (The evaluation result looks fine thoug…

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## [A problem with SOCP constraint](https://discourse.julialang.org/t/a-problem-with-socp-constraint/79414)

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**Author:** [@mahon](https://discourse.julialang.org/u/mahon)\
**Replies:** 4\
**Last updated:** [April 13, 2022, 5:03am UTC](https://discourse.julialang.org/t/a-problem-with-socp-constraint/79414 "2022-04-13T05:03:41Z")

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I want to formulate a SOCP constraint like this using Mosek and my code here all variables are 32 × 24 matrix，but it pulls a error and if i give the concrete row and columns ，it works

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## [Error Handling in Quote Block using JuMP](https://discourse.julialang.org/t/error-handling-in-quote-block-using-jump/79362)

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**Author:** [@hdavid16](https://discourse.julialang.org/u/hdavid16)\
**Replies:** 10\
**Last updated:** [April 13, 2022, 4:44am UTC](https://discourse.julialang.org/t/error-handling-in-quote-block-using-jump/79362 "2022-04-13T04:44:03Z")

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I am puzzled by the following: using JuMP m = Model() @variable(m,x) code = quote try 1 catch e @NLconstraint($m, 0 .\<= exp($x)) end end eval(code) ERROR: At REPL\[240\]:5: \`@NLconstraint(Fe…

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## [Indexing on Vectorized Constraints in JuMP](https://discourse.julialang.org/t/indexing-on-vectorized-constraints-in-jump/79382)

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**Author:** [@hdavid16](https://discourse.julialang.org/u/hdavid16)\
**Replies:** 4\
**Last updated:** [April 12, 2022, 11:46pm UTC](https://discourse.julialang.org/t/indexing-on-vectorized-constraints-in-jump/79382 "2022-04-12T23:46:21Z")

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I was looking at the example for vectorized constraints in the docs (Constraints · JuMP), which creates the constraint: @constraint(model, con, A \* x .== b) 2-element Vector{ConstraintRef{Model, MathOptInterface.Constr…

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## [Convexity-Preserving Rational Interpolation](https://discourse.julialang.org/t/convexity-preserving-rational-interpolation/79112)

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**Author:** [@liamfdoherty](https://discourse.julialang.org/u/liamfdoherty)\
**Replies:** 11\
**Last updated:** [April 12, 2022, 10:08pm UTC](https://discourse.julialang.org/t/convexity-preserving-rational-interpolation/79112 "2022-04-12T22:08:54Z")

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Hi all! First time poster here. I have a univariate convex function that I would like to optimize. However, it is very expensive to evaluate (due to large variances from Monte Carlo estimation) and I would like to inter…

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## [\[Flux / Zygote\] Circumvent long compilation times](https://discourse.julialang.org/t/flux-zygote-circumvent-long-compilation-times/79385)

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**Author:** [@Tengrath](https://discourse.julialang.org/u/Tengrath)\
**Replies:** 1\
**Last updated:** [April 12, 2022, 8:30pm UTC](https://discourse.julialang.org/t/flux-zygote-circumvent-long-compilation-times/79385 "2022-04-12T20:30:33Z")

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I have implemented a custom physics in model Flux / Zygote to benefit from gradient-based optimization of these great packages. It contains custom layers, each shipping its own ChainRulesCore.rrule. A single model contai…

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## [Suppressing Info blocks from StructuralIdentifiability](https://discourse.julialang.org/t/suppressing-info-blocks-from-structuralidentifiability/79388)

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**Author:** [@bendkok](https://discourse.julialang.org/u/bendkok)\
**Replies:** 6\
**Last updated:** [April 12, 2022, 8:04pm UTC](https://discourse.julialang.org/t/suppressing-info-blocks-from-structuralidentifiability/79388 "2022-04-12T20:04:13Z")

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Hi. I’m using the Julia package StructuralIdentifiability. To use it we first define an ODE-model, and then check the identifiability of its parameters. When I do either of those it prints these “Info:” blocks that take…

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## [Getting constraint matrix from gurobi](https://discourse.julialang.org/t/getting-constraint-matrix-from-gurobi/79107)

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**Author:** [@shsh](https://discourse.julialang.org/u/shsh)\
**Replies:** 5\
**Last updated:** [April 12, 2022, 7:58pm UTC](https://discourse.julialang.org/t/getting-constraint-matrix-from-gurobi/79107 "2022-04-12T19:58:41Z")

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Is there an easy way to obtain the current constraint matrix from gurobi (or the original constraint matrix and inverse of the basis matrix) using MathOptInterface. I have been searching google and only found how to do …

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## [How to use string in @nlexpression](https://discourse.julialang.org/t/how-to-use-string-in-nlexpression/79374)

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**Author:** [@manoj.centura](https://discourse.julialang.org/u/manoj.centura)\
**Replies:** 1\
**Last updated:** [April 12, 2022, 6:47pm UTC](https://discourse.julialang.org/t/how-to-use-string-in-nlexpression/79374 "2022-04-12T18:47:59Z")

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Hi All, i want to create @NL expreesion on fly in JuMP. I am getting the below error. model = Model() @variable(model, x\[1:3\]) @constraint(model, c2, x\[1\] + 2 \* x\[3\] \>= 2) @constraint(model, c4, 4 \<= 2 \* x\[2\] \<= 5) …

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## [Help me beat my pythonist friend's code. Speeding up data reading with simple reduction from NetCDF file](https://discourse.julialang.org/t/help-me-beat-my-pythonist-friends-code-speeding-up-data-reading-with-simple-reduction-from-netcdf-file/76457)

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**Author:** [@aramirezreyes](https://discourse.julialang.org/u/aramirezreyes)\
**Replies:** 57\
**Last updated:** [April 12, 2022, 4:35pm UTC](https://discourse.julialang.org/t/help-me-beat-my-pythonist-friends-code-speeding-up-data-reading-with-simple-reduction-from-netcdf-file/76457 "2022-04-12T16:35:49Z")

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I work with atmospheric simulations and I use NetCDF files of the order of 80GB to 1TB. I am always jelous at my friend from the office (@lsterzinger) that does everything super fast in his python with xarray, zarr, da…

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## [Working around current MethodOfLines.jl known limitations](https://discourse.julialang.org/t/working-around-current-methodoflines-jl-known-limitations/79346)

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**Author:** [@jenrei](https://discourse.julialang.org/u/jenrei)\
**Replies:** 4\
**Last updated:** [April 12, 2022, 4:25pm UTC](https://discourse.julialang.org/t/working-around-current-methodoflines-jl-known-limitations/79346 "2022-04-12T16:25:58Z")

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Hi, I’m trying to solve the energy/heat equation with temperature dependent material properties (density, enthalpy and thermal conductivity). Therefore I’m running in the issues that are mentioned as (current) known limi…

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## [Mapping Hwloc logical index to OS index](https://discourse.julialang.org/t/mapping-hwloc-logical-index-to-os-index/79377)

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**Author:** [@Gregstrq](https://discourse.julialang.org/u/Gregstrq)\
**Replies:** 5\
**Last updated:** [April 12, 2022, 3:12pm UTC](https://discourse.julialang.org/t/mapping-hwloc-logical-index-to-os-index/79377 "2022-04-12T15:12:29Z")

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The docs for Hwloc library state that the logical indices of Processor units used by Hwloc are not the same as the indices used by OS. How does one map Hwloc logical indices to OS indices? Is this functionality exposed…

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