# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=88

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**Page:** 89

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## [Misspecified Turing.jl model?](https://discourse.julialang.org/t/misspecified-turing-jl-model/118451)

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**Author:** [@Domenic\_Di\_Francesco](https://discourse.julialang.org/u/Domenic_Di_Francesco)\
**Replies:** 2\
**Last updated:** [August 28, 2024, 3:22pm UTC](https://discourse.julialang.org/t/misspecified-turing-jl-model/118451 "2024-08-28T15:22:16Z")

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hi everyone - I’m thinking I may have miss-specified a Turing model :thinking: I want to combine measurements of X, from 2 tests: test A, has a known precision (test\_A\_error) test B has an unknown precision (test\_B\_er…

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## [How to efficiently generate a distribution for every element in matrix](https://discourse.julialang.org/t/how-to-efficiently-generate-a-distribution-for-every-element-in-matrix/118695)

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**Author:** [@ZC\_H](https://discourse.julialang.org/u/ZC_H)\
**Replies:** 2\
**Last updated:** [August 28, 2024, 7:23am UTC](https://discourse.julialang.org/t/how-to-efficiently-generate-a-distribution-for-every-element-in-matrix/118695 "2024-08-28T07:23:21Z")

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for example, I have two matrix which separately represent mu and std: mu = \[1.0 2.0; 3.0 4.0\] std = \[0.1 0.2; 0.3 0.4\] I want to generate a matrix Normal Distribution like this: dist = \[Normal(1.0, 0.1) Normal(2.0, 0.…

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## [Tips on implementing a hybrid system](https://discourse.julialang.org/t/tips-on-implementing-a-hybrid-system/118649)

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**Author:** [@sdwfrost](https://discourse.julialang.org/u/sdwfrost)\
**Replies:** 4\
**Last updated:** [August 27, 2024, 2:26pm UTC](https://discourse.julialang.org/t/tips-on-implementing-a-hybrid-system/118649 "2024-08-27T14:26:01Z")

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I’d like to implement a hybrid model using the SciML ecosystem, that switches between a jump process (at ‘low’ population sizes) and an SDE. Individual examples of these models are here and here. Any suggestions on best …

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## [RxInfer Domain Logic](https://discourse.julialang.org/t/rxinfer-domain-logic/117355)

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**Author:** [@spolk](https://discourse.julialang.org/u/spolk)\
**Replies:** 3\
**Last updated:** [August 27, 2024, 12:46pm UTC](https://discourse.julialang.org/t/rxinfer-domain-logic/117355 "2024-08-27T12:46:45Z")

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Hello! I am trying to modify this example from RxInfer.jl’s documentation and get an error saying I didn’t initialize marginals when two unobserved states influence multiple observable results in the domain logic in a B…

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## [Flux: if shuffle=false in DataLoader, is Descent "not" SGD?](https://discourse.julialang.org/t/flux-if-shuffle-false-in-dataloader-is-descent-not-sgd/118659)

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**Author:** [@tom-plaa](https://discourse.julialang.org/u/tom-plaa)\
**Replies:** 0\
**Last updated:** [August 27, 2024, 12:33pm UTC](https://discourse.julialang.org/t/flux-if-shuffle-false-in-dataloader-is-descent-not-sgd/118659 "2024-08-27T12:33:46Z")

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Sorry for the stupid question, but it’s like in the title: When using DataLoader, if we don’t set shuffle=true, will the gradient descent algorithm from Descent always go through the batches/samples in the same order fo…

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## [Parameter inference for agents based model](https://discourse.julialang.org/t/parameter-inference-for-agents-based-model/118613)

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**Author:** [@Sahil\_Khan](https://discourse.julialang.org/u/Sahil_Khan)\
**Replies:** 3\
**Last updated:** [August 26, 2024, 11:41pm UTC](https://discourse.julialang.org/t/parameter-inference-for-agents-based-model/118613 "2024-08-26T23:41:39Z")

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Hello everyone, Im doing parameter inference for my agent based model. At the moment, Im using NUTS() from Turing package. Im not sure if its the right choice as model is stochastic in nature. I was wondering that if a A…

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## [Matrix Multiplication Using oneAPI.jl Fails on Second Invocation](https://discourse.julialang.org/t/matrix-multiplication-using-oneapi-jl-fails-on-second-invocation/118567)

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**Author:** [@Marcelo\_Simas](https://discourse.julialang.org/u/Marcelo_Simas)\
**Replies:** 3\
**Last updated:** [August 26, 2024, 3:16pm UTC](https://discourse.julialang.org/t/matrix-multiplication-using-oneapi-jl-fails-on-second-invocation/118567 "2024-08-26T15:16:27Z")

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Been playing with oneAPI.jl to run matrix x vector multiplication using the integrated Intel GPU on my Windows laptop (WSL2) and came across a strange behavior. The first time mul!() is invoked I get a reasonable result…

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## [Code that uses MPI.jl does not run on cluster](https://discourse.julialang.org/t/code-that-uses-mpi-jl-does-not-run-on-cluster/118167)

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**Author:** [@Uranium238](https://discourse.julialang.org/u/Uranium238)\
**Replies:** 24\
**Last updated:** [August 26, 2024, 3:04pm UTC](https://discourse.julialang.org/t/code-that-uses-mpi-jl-does-not-run-on-cluster/118167 "2024-08-26T15:04:14Z")

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I have written a version of my code that uses MPI.jl to achieve a potentially large scale parallelization. I already had MPI installed on my PC and used the instructions from here to make sure that the same mpiexec is be…

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## [Learning curve for validation dataset](https://discourse.julialang.org/t/learning-curve-for-validation-dataset/118529)

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**Author:** [@niltsz](https://discourse.julialang.org/u/niltsz)\
**Replies:** 1\
**Last updated:** [August 26, 2024, 8:17am UTC](https://discourse.julialang.org/t/learning-curve-for-validation-dataset/118529 "2024-08-26T08:17:31Z")

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I want to train a ML model with MLJ, for example an XGBoost Regressor with L2 Loss. I split my dataset into three parts, train/val/test, and during training I want to train on the train dataset but also plot the loss/ac…

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## [Stacked area plots in Makie](https://discourse.julialang.org/t/stacked-area-plots-in-makie/118574)

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**Author:** [@mjmat](https://discourse.julialang.org/u/mjmat)\
**Replies:** 6\
**Last updated:** [August 26, 2024, 5:29am UTC](https://discourse.julialang.org/t/stacked-area-plots-in-makie/118574 "2024-08-26T05:29:58Z")

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This seems like a very simple question, but what is the easiest way to create a stacked area plot in Makie? I can’t seem to find that in the (very good) tutorials and documentation. A short example in PlotlyJS: using P…

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## [How to use Flux to write a Multi-Head Output Network](https://discourse.julialang.org/t/how-to-use-flux-to-write-a-multi-head-output-network/118605)

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**Author:** [@ZC\_H](https://discourse.julialang.org/u/ZC_H)\
**Replies:** 4\
**Last updated:** [August 26, 2024, 3:30am UTC](https://discourse.julialang.org/t/how-to-use-flux-to-write-a-multi-head-output-network/118605 "2024-08-26T03:30:34Z")

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I want to use julia.Flux to recurrent SAC algorithm. But I am facing a problem when I write the policy network modular because it is a multi-head output network, which receive a state matrix as input and output both expe…

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## [ApproxFun: how to define initial conditions for a second-order ODE?](https://discourse.julialang.org/t/approxfun-how-to-define-initial-conditions-for-a-second-order-ode/15295)

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**Author:** [@zdenek\_hurak](https://discourse.julialang.org/u/zdenek_hurak)\
**Replies:** 4\
**Last updated:** [August 25, 2024, 9:09pm UTC](https://discourse.julialang.org/t/approxfun-how-to-define-initial-conditions-for-a-second-order-ode/15295 "2024-08-25T21:09:49Z")

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Hello, I am struggling with the very basics of usage of ApproxFun package. I would like to use it solve the very simplest second-order linear initial value problem \\ddot u(t) + \\dot u(t) + u(t) = 0, u(0) = 1, \\dot u(0) …

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## [NeuralODE training failed on GPU with Enzyme](https://discourse.julialang.org/t/neuralode-training-failed-on-gpu-with-enzyme/118537)

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**Author:** [@Yunan](https://discourse.julialang.org/u/Yunan)\
**Replies:** 6\
**Last updated:** [August 25, 2024, 8:41pm UTC](https://discourse.julialang.org/t/neuralode-training-failed-on-gpu-with-enzyme/118537 "2024-08-25T20:41:49Z")

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Hi, when I try to train a NeuralODE with Discretecallback using 'sensealg=InterpolatingAdjoint(autojacvec=EnzymeVJP(), checkpointing=true) ’ , I get: Enzyme execution failed. Enzyme: unhandled augmented forward for jl\_…

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## [Questions about CUDA.dot() function](https://discourse.julialang.org/t/questions-about-cuda-dot-function/99315)

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**Author:** [@fred\_wu](https://discourse.julialang.org/u/fred_wu)\
**Replies:** 4\
**Last updated:** [August 25, 2024, 5:05pm UTC](https://discourse.julialang.org/t/questions-about-cuda-dot-function/99315 "2024-08-25T17:05:54Z")

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Hi, I encountered two doubts when using the CUDA.dot() function. My understanding is that the CUDA.dot() function returns a CPU scalar after performing calculations on the GPU. I tested the running time of the CUDA.dot(…

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## [Why FlowDivider and Valve are not exported in MTK Standard Library?](https://discourse.julialang.org/t/why-flowdivider-and-valve-are-not-exported-in-mtk-standard-library/118571)

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**Author:** [@romantimo](https://discourse.julialang.org/u/romantimo)\
**Replies:** 4\
**Last updated:** [August 24, 2024, 8:14pm UTC](https://discourse.julialang.org/t/why-flowdivider-and-valve-are-not-exported-in-mtk-standard-library/118571 "2024-08-24T20:14:51Z")

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I see many useful components (FlowDivider, Valve, Actuator, SpoolValve…) in src/Hydraulic/IsothermalCompressible/components.jl Any reason why they are not exported? @ChrisRackauckas Thanks a lot for making MTK with st…

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## [There's a hole in a sphere generated by makie.surface](https://discourse.julialang.org/t/theres-a-hole-in-a-sphere-generated-by-makie-surface/118555)

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**Author:** [@xczphysics](https://discourse.julialang.org/u/xczphysics)\
**Replies:** 8\
**Last updated:** [August 24, 2024, 5:38pm UTC](https://discourse.julialang.org/t/theres-a-hole-in-a-sphere-generated-by-makie-surface/118555 "2024-08-24T17:38:12Z")

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Take a look at this Eye !!! Unlike mesh(spheremesh) method, current surface(x,y,z) method leaves a circular hole at the north pole of the ball, see: Transparent surfaces in Makie.jl - #2 by sdanisch CairoMakie inve…

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## [Excessively long TTFX with Optimization and OptimizationOptimJL](https://discourse.julialang.org/t/excessively-long-ttfx-with-optimization-and-optimizationoptimjl/118457)

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**Author:** [@aris](https://discourse.julialang.org/u/aris)\
**Replies:** 22\
**Last updated:** [August 24, 2024, 1:27pm UTC](https://discourse.julialang.org/t/excessively-long-ttfx-with-optimization-and-optimizationoptimjl/118457 "2024-08-24T13:27:28Z")

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Suppose we would like to solve the following problem : min ||Ax - b||\_2^2, s.t. x.\>0 using OptimizationOptimJl. One way to write it would be as follows: using Optimization, OptimizationOptimJL function obj\_f(x,p)…

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## [Mixed-integer quadratic programming doesn't seem to be working correctly](https://discourse.julialang.org/t/mixed-integer-quadratic-programming-doesnt-seem-to-be-working-correctly/118551)

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**Author:** [@Tarny\_GG\_Channie](https://discourse.julialang.org/u/Tarny_GG_Channie)\
**Replies:** 1\
**Last updated:** [August 24, 2024, 9:30am UTC](https://discourse.julialang.org/t/mixed-integer-quadratic-programming-doesnt-seem-to-be-working-correctly/118551 "2024-08-24T09:30:50Z")

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DAQP was supposedly solving convex mixed-binary quadratic programming until I tried. The GitHub page said that the matrix must be positive semi-definite, which it is. (The objective expression literally cannot be less…

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## [Synchronize streams in CUDA.jl](https://discourse.julialang.org/t/synchronize-streams-in-cuda-jl/118127)

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**Author:** [@Cibin\_Joseph](https://discourse.julialang.org/u/Cibin_Joseph)\
**Replies:** 11\
**Last updated:** [August 23, 2024, 10:58pm UTC](https://discourse.julialang.org/t/synchronize-streams-in-cuda-jl/118127 "2024-08-23T22:58:47Z")

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Which of the synchronize commands is supposed to be used to synchronize the streams in CUDA? I am able to synchronize them with device\_synchronize(), but this seems to have a huge impact on speed. Is there perhaps a more…

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## [Jacobian calculation with FastDifferentiation.jl](https://discourse.julialang.org/t/jacobian-calculation-with-fastdifferentiation-jl/118501)

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**Author:** [@niro](https://discourse.julialang.org/u/niro)\
**Replies:** 2\
**Last updated:** [August 23, 2024, 6:38pm UTC](https://discourse.julialang.org/t/jacobian-calculation-with-fastdifferentiation-jl/118501 "2024-08-23T18:38:15Z")

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Hi there, I wanted to test this package to compute the Jacobian of a relatively lengthy function. However, I encounter an issue because the result is apparently not correct if I compare with other methods. Yet, the cod…

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## [MAP optimization in Turing with LBFGS doesn't move at all](https://discourse.julialang.org/t/map-optimization-in-turing-with-lbfgs-doesnt-move-at-all/118431)

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**Author:** [@dlakelan](https://discourse.julialang.org/u/dlakelan)\
**Replies:** 22\
**Last updated:** [August 23, 2024, 3:31pm UTC](https://discourse.julialang.org/t/map-optimization-in-turing-with-lbfgs-doesnt-move-at-all/118431 "2024-08-23T15:31:48Z")

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I’m using maximum\_a\_posteriori to try to find a MAP fit for a complex model that I can’t show you at the moment. If I run it with SAMIN() simulated annealing, or BBO\_de\_... algorithms, it does move around and finds part…

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## [Large allocation problem while simulating agents model](https://discourse.julialang.org/t/large-allocation-problem-while-simulating-agents-model/118522)

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**Author:** [@Sahil\_Khan](https://discourse.julialang.org/u/Sahil_Khan)\
**Replies:** 12\
**Last updated:** [August 23, 2024, 2:18pm UTC](https://discourse.julialang.org/t/large-allocation-problem-while-simulating-agents-model/118522 "2024-08-23T14:18:30Z")

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Hello, This is a continuation of previous thread multithreading in agents. I have put an example here which overall is weird as a model but gives idea of memory allocation regions in my original model. Please ignore if y…

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## [Compose Vector and Scalar Equations together](https://discourse.julialang.org/t/compose-vector-and-scalar-equations-together/118474)

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**Author:** [@HSnowden](https://discourse.julialang.org/u/HSnowden)\
**Replies:** 7\
**Last updated:** [August 23, 2024, 12:48pm UTC](https://discourse.julialang.org/t/compose-vector-and-scalar-equations-together/118474 "2024-08-23T12:48:47Z")

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When I try to connect an equation of scalars with an equation of vectors, something on the compose step fails even though what is being connected is the same type (both scalar etc.). I am not sure why this is. An MWE is …

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## [Multithreading in Agents.jl](https://discourse.julialang.org/t/multithreading-in-agents-jl/118452)

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**Author:** [@Sahil\_Khan](https://discourse.julialang.org/u/Sahil_Khan)\
**Replies:** 11\
**Last updated:** [August 23, 2024, 8:21am UTC](https://discourse.julialang.org/t/multithreading-in-agents-jl/118452 "2024-08-23T08:21:24Z")

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Hello everyone, Im trying to use multithreading in EventBasedModel. Im getting this error while doing this. Can someone comment ? What can be issue? What is this error trying to say? Threads.@threads for agen…

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## [Handling Instability When Solving ODE Problems](https://discourse.julialang.org/t/handling-instability-when-solving-ode-problems/9019)

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**Author:** [@Torkel](https://discourse.julialang.org/u/Torkel)\
**Replies:** 14\
**Last updated:** [August 23, 2024, 6:48am UTC](https://discourse.julialang.org/t/handling-instability-when-solving-ode-problems/9019 "2024-08-23T06:48:55Z")

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I have a model which have previously been constructed in matlab, now I want to try that model in Julia. (The model is a system of differential equations in 5 variables which oscillates) In matlab it is solved successfu…

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## [NCDatasets: performance issues deriving fast Minimum Maximum value as too slow](https://discourse.julialang.org/t/ncdatasets-performance-issues-deriving-fast-minimum-maximum-value-as-too-slow/118468)

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**Author:** [@JosephPollacco](https://discourse.julialang.org/u/JosephPollacco)\
**Replies:** 12\
**Last updated:** [August 23, 2024, 4:14am UTC](https://discourse.julialang.org/t/ncdatasets-performance-issues-deriving-fast-minimum-maximum-value-as-too-slow/118468 "2024-08-23T04:14:54Z")

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:turtle: :turtle: :turtle: :turtle: Finding minimum and maximum of a NetCDF files due to missing values is painfully slow. It takes me 2 minutes to perform this simple task: "NameOutput="SoilWater" Output\_NCDatasets =…

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## [Makie - update volumeslices](https://discourse.julialang.org/t/makie-update-volumeslices/116729)

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**Author:** [@Oleg\_Melnik](https://discourse.julialang.org/u/Oleg_Melnik)\
**Replies:** 3\
**Last updated:** [August 22, 2024, 9:14pm UTC](https://discourse.julialang.org/t/makie-update-volumeslices/116729 "2024-08-22T21:14:18Z")

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I am trying to add a timestep slider to the standard example from volumeslices | Makie to update the vol array I did not find a method how to update the dataset and redraw the diagram after I change the value of the sl…

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## [To confirm: The sign of the dual variable on a constraint of \`JuMP\` model](https://discourse.julialang.org/t/to-confirm-the-sign-of-the-dual-variable-on-a-constraint-of-jump-model/114292)

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**Author:** [@WuSiren](https://discourse.julialang.org/u/WuSiren)\
**Replies:** 7\
**Last updated:** [August 22, 2024, 5:50pm UTC](https://discourse.julialang.org/t/to-confirm-the-sign-of-the-dual-variable-on-a-constraint-of-jump-model/114292 "2024-08-22T17:50:30Z")

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To make it more clear, let’s consider an optimization problem of the following standard form: \\begin{equation} \\begin{array}{cl} {\\min} & {f\_0(x)}\\\\ {\\mathrm{s.t.}} & {f\_i(x)\\leqslant 0,\\quad i=1,\\c…

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## [Creating MTK components](https://discourse.julialang.org/t/creating-mtk-components/118426)

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**Author:** [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Replies:** 4\
**Last updated:** [August 22, 2024, 5:43pm UTC](https://discourse.julialang.org/t/creating-mtk-components/118426 "2024-08-22T17:43:49Z")

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I created a nice tether model using MTK. Now the question arises, can I create an MTK component out of it. It would need two or three ports: at point one a force vector and and a speed vector at point two the same in …

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## [Computing the jacobian of NN while using Lux](https://discourse.julialang.org/t/computing-the-jacobian-of-nn-while-using-lux/93059)

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**Author:** [@clm](https://discourse.julialang.org/u/clm)\
**Replies:** 6\
**Last updated:** [August 22, 2024, 2:17pm UTC](https://discourse.julialang.org/t/computing-the-jacobian-of-nn-while-using-lux/93059 "2024-08-22T14:17:05Z")

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I’m revisiting some code I was working on a while ago and rewrite it from Flux to Lux. Previously, I was trying to use DiffEqFlux to solve for a neural network U where my differential equation contains both U(\[x,y,t\],p) …

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