# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=104

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**Page:** 105

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## [MethodOfLines issue with coupled non-linear PDE system](https://discourse.julialang.org/t/methodoflines-issue-with-coupled-non-linear-pde-system/115681)

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**Author:** [@Ryan\_B](https://discourse.julialang.org/u/Ryan_B)\
**Replies:** 2\
**Last updated:** [June 16, 2024, 4:15am UTC](https://discourse.julialang.org/t/methodoflines-issue-with-coupled-non-linear-pde-system/115681 "2024-06-16T04:15:18Z")

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Hi. I am trying to solve a coupled system of nonlinear PDEs. I have attached the code, and I am happy to answer any questions. I have a 2D domain (x,z) and time dependence. My two variables are c (x,z,t), a 2D concentrat…

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## [ModelingToolkit for nonlinear circuits and interface with fixed time-step simulators](https://discourse.julialang.org/t/modelingtoolkit-for-nonlinear-circuits-and-interface-with-fixed-time-step-simulators/115628)

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**Author:** [@kevjzheng](https://discourse.julialang.org/u/kevjzheng)\
**Replies:** 4\
**Last updated:** [June 15, 2024, 9:51pm UTC](https://discourse.julialang.org/t/modelingtoolkit-for-nonlinear-circuits-and-interface-with-fixed-time-step-simulators/115628 "2024-06-15T21:51:48Z")

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Hi all, I am relatively new to Julia and believe MTK offers an efficient way to model nonlinear circuits/communication channels for an existing link simulation framework I am building. As shown in the picture, most …

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## [Optimization.jl and Lux.jl 1.10.0 Compatability](https://discourse.julialang.org/t/optimization-jl-and-lux-jl-1-10-0-compatability/108590)

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**Author:** [@afulkers](https://discourse.julialang.org/u/afulkers)\
**Replies:** 3\
**Last updated:** [June 15, 2024, 12:47pm UTC](https://discourse.julialang.org/t/optimization-jl-and-lux-jl-1-10-0-compatability/108590 "2024-06-15T12:47:35Z")

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I was revisiting code I wrote in Julia 1.9.3 which closely mimics the code written by Chris here. While it worked fine in 1.9.3, when I updated my packages and installation to 1.10.0. I started getting the following erro…

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## [Problems with reverse mode automatic diff (e.g. zygote) with NeuralSDEs](https://discourse.julialang.org/t/problems-with-reverse-mode-automatic-diff-e-g-zygote-with-neuralsdes/113501)

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**Author:** [@agelgazzar](https://discourse.julialang.org/u/agelgazzar)\
**Replies:** 2\
**Last updated:** [June 15, 2024, 11:17am UTC](https://discourse.julialang.org/t/problems-with-reverse-mode-automatic-diff-e-g-zygote-with-neuralsdes/113501 "2024-06-15T11:17:57Z")

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Hello, I am having difficulty computing gradients of a neural sdes (either custom or in DiffeqFlux) using Zygote or ReverseDiff. I think it has to do with the shape of the noise during the backward pass but I am not su…

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## [Fitting values in a vector to separate Onlinestats Univariate statistics](https://discourse.julialang.org/t/fitting-values-in-a-vector-to-separate-onlinestats-univariate-statistics/115664)

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**Author:** [@Dario\_Sarra](https://discourse.julialang.org/u/Dario_Sarra)\
**Replies:** 1\
**Last updated:** [June 15, 2024, 11:16am UTC](https://discourse.julialang.org/t/fitting-values-in-a-vector-to-separate-onlinestats-univariate-statistics/115664 "2024-06-15T11:16:22Z")

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My final goal was to compute N separate Means after vectorizing a CircularBuffer Matrix and update the means after a certain number of steps of the Circular buffer. I know how to get separate calculations using LinearAlg…

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## [PDE with neural network and derivative of NN using MethodOfLines](https://discourse.julialang.org/t/pde-with-neural-network-and-derivative-of-nn-using-methodoflines/114673)

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**Author:** [@jenrei](https://discourse.julialang.org/u/jenrei)\
**Replies:** 2\
**Last updated:** [June 15, 2024, 11:15am UTC](https://discourse.julialang.org/t/pde-with-neural-network-and-derivative-of-nn-using-methodoflines/114673 "2024-06-15T11:15:09Z")

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I want to solve the energy equation where the potential energy is expressed by a neural network and then solved for a prescribed energy (actually temperature) profile. So a very simplified version of my problem would loo…

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## [Visualize the points that are used for training in NeuralPDE](https://discourse.julialang.org/t/visualize-the-points-that-are-used-for-training-in-neuralpde/114666)

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**Author:** [@PetrosStefanou](https://discourse.julialang.org/u/PetrosStefanou)\
**Replies:** 1\
**Last updated:** [June 15, 2024, 11:07am UTC](https://discourse.julialang.org/t/visualize-the-points-that-are-used-for-training-in-neuralpde/114666 "2024-06-15T11:07:07Z")

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Hi, I would like to print and visualize the points that are being selected at each iteration by the QuasiRandomTraining strategy in NeuralPDE. I have checked the many fields of symbolic\_discretize but I cannot pinpoint…

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## [CUB wrapper ccall overhead on Windows](https://discourse.julialang.org/t/cub-wrapper-ccall-overhead-on-windows/115585)

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**Author:** [@eldee](https://discourse.julialang.org/u/eldee)\
**Replies:** 10\
**Last updated:** [June 15, 2024, 10:37am UTC](https://discourse.julialang.org/t/cub-wrapper-ccall-overhead-on-windows/115585 "2024-06-15T10:37:35Z")

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Hi, To get a faster GPU sort + sortperm for a specific use case, I succesfully wrapped CUB’s SortPairs method for sorting 64-bit integer keys (sort) and 32-bit integer values (sortperm). However, when measuring the exec…

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## [MTK - instantiate \*vectors\* of models?](https://discourse.julialang.org/t/mtk-instantiate-vectors-of-models/113487)

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**Author:** [@BLI](https://discourse.julialang.org/u/BLI)\
**Replies:** 1\
**Last updated:** [June 15, 2024, 10:34am UTC](https://discourse.julialang.org/t/mtk-instantiate-vectors-of-models/113487 "2024-06-15T10:34:15Z")

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Is it possible to instantiate vectors of models in MTK? What I mean is the following. I have created a re-usable “class” which I have named Well. In the past, I have instantiated several copies of this model and used th…

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## [Automatic State Transition Matrix](https://discourse.julialang.org/t/automatic-state-transition-matrix/115657)

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**Author:** [@afossa](https://discourse.julialang.org/u/afossa)\
**Replies:** 3\
**Last updated:** [June 15, 2024, 10:02am UTC](https://discourse.julialang.org/t/automatic-state-transition-matrix/115657 "2024-06-15T10:02:53Z")

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Hello, When solving an ODE with the DifferentialEquations package, is there a way to automatically retrieve the state transition matrix, i.e. the sensitivity of the solution w.r.t. the initial conditions, along the enti…

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## [Implementing two different noise processes in a differential equation](https://discourse.julialang.org/t/implementing-two-different-noise-processes-in-a-differential-equation/101908)

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**Author:** [@absorbtion](https://discourse.julialang.org/u/absorbtion)\
**Replies:** 1\
**Last updated:** [June 15, 2024, 10:01am UTC](https://discourse.julialang.org/t/implementing-two-different-noise-processes-in-a-differential-equation/101908 "2024-06-15T10:01:47Z")

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Hi! I’m trying to implement the 3-dim complex valued DE du/dt = (alpha(t) + beta(t))\*u(t) alpha(t) is a 3-dim OU process and beta(t) is a 1-dim OU process (mean 0) with a given covariance E\[beta(t)beta(s)\] = f(s,t). I…

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## [Nonlinear Least Squares Millions of Allocations](https://discourse.julialang.org/t/nonlinear-least-squares-millions-of-allocations/115583)

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**Author:** [@nicrummel](https://discourse.julialang.org/u/nicrummel)\
**Replies:** 9\
**Last updated:** [June 15, 2024, 1:43am UTC](https://discourse.julialang.org/t/nonlinear-least-squares-millions-of-allocations/115583 "2024-06-15T01:43:44Z")

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Overview An algorithm I am working on requires solving many largish nonlinear least squares problems. The number of allocations is exploding. My nonlinear function are efficient when passed Arrays of Float64 and generate…

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## [Plotting DifferentialEquations.jl solutions, re-indexing](https://discourse.julialang.org/t/plotting-differentialequations-jl-solutions-re-indexing/108106)

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**Author:** [@aoifehealy](https://discourse.julialang.org/u/aoifehealy)\
**Replies:** 7\
**Last updated:** [June 14, 2024, 6:51pm UTC](https://discourse.julialang.org/t/plotting-differentialequations-jl-solutions-re-indexing/108106 "2024-06-14T18:51:08Z")

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Hi there, I am solving a system of differential equations using Differential equations.jl, and have the following result: I would like to only plot the solution when it has stabilised (from 5 seconds onwards). I have …

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## [MTK system based on symbolic arrays fails: type Array has no field lhs](https://discourse.julialang.org/t/mtk-system-based-on-symbolic-arrays-fails-type-array-has-no-field-lhs/110455)

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**Author:** [@fabianmueller](https://discourse.julialang.org/u/fabianmueller)\
**Replies:** 2\
**Last updated:** [June 14, 2024, 4:48pm UTC](https://discourse.julialang.org/t/mtk-system-based-on-symbolic-arrays-fails-type-array-has-no-field-lhs/110455 "2024-06-14T16:48:22Z")

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I struggle a little bit with a relatively simple MTK model that contains matrix vector multiplications. My example code is the following: using ModelingToolkit Am = \[1 0 3; 2 0 1; 0 1 4\] Bm = \[4 5; 3 2; 1 4\] @paramete…

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## [Accelerating repeated eigenvalue searches](https://discourse.julialang.org/t/accelerating-repeated-eigenvalue-searches/114989)

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**Author:** [@bremez](https://discourse.julialang.org/u/bremez)\
**Replies:** 31\
**Last updated:** [June 14, 2024, 2:08pm UTC](https://discourse.julialang.org/t/accelerating-repeated-eigenvalue-searches/114989 "2024-06-14T14:08:23Z")

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I need to compute the eigenvalues of 2N\\times2N (N ~ 1000) complex, hermitian, dense, matrices, the number of matrices being ~100. They have the following properties: All matrices M\_i take the form M\_i = A + D\_i, where…

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## [HallThruster.jl package Simulations : issue with the tutorial and the running of the simulation](https://discourse.julialang.org/t/hallthruster-jl-package-simulations-issue-with-the-tutorial-and-the-running-of-the-simulation/115594)

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**Author:** [@bboy\_eleven](https://discourse.julialang.org/u/bboy_eleven)\
**Replies:** 1\
**Last updated:** [June 14, 2024, 9:23am UTC](https://discourse.julialang.org/t/hallthruster-jl-package-simulations-issue-with-the-tutorial-and-the-running-of-the-simulation/115594 "2024-06-14T09:23:33Z")

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Hi, I’m currently learning and using the package HallThruster.jl wich is used for simulating Hall Thruster in 1D. A tutorial is available Home · HallThruster.jl and is well detailed and how to use the package. At first …

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## [ModellingToolkit issue with creating ODEProblem](https://discourse.julialang.org/t/modellingtoolkit-issue-with-creating-odeproblem/115560)

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**Author:** [@rveynde](https://discourse.julialang.org/u/rveynde)\
**Replies:** 2\
**Last updated:** [June 14, 2024, 7:02am UTC](https://discourse.julialang.org/t/modellingtoolkit-issue-with-creating-odeproblem/115560 "2024-06-14T07:02:33Z")

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Hi all, I have encountered the same error multiple times when building a model, and I am not sure whether it is a bug or whether I am building the model wrong. Below is an example of the type of model that I am trying t…

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## [Calling repeat with a CUDA array changes the state of the random number generator](https://discourse.julialang.org/t/calling-repeat-with-a-cuda-array-changes-the-state-of-the-random-number-generator/115598)

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**Author:** [@Alexander-Barth](https://discourse.julialang.org/u/Alexander-Barth)\
**Replies:** 2\
**Last updated:** [June 14, 2024, 6:09am UTC](https://discourse.julialang.org/t/calling-repeat-with-a-cuda-array-changes-the-state-of-the-random-number-generator/115598 "2024-06-14T06:09:30Z")

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I am trying to refactor a code with uses random numbers and CUDA arrays. Quite surprisingly the function repeat changes the sequence of random numbers. I am wondering if other people see the same behavior. Do I miss s…

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## [End-of-horizon effect, Infinite horizon policy graph, SDDP.jl](https://discourse.julialang.org/t/end-of-horizon-effect-infinite-horizon-policy-graph-sddp-jl/115573)

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**Author:** [@Sorooshsa](https://discourse.julialang.org/u/Sorooshsa)\
**Replies:** 11\
**Last updated:** [June 14, 2024, 12:52am UTC](https://discourse.julialang.org/t/end-of-horizon-effect-infinite-horizon-policy-graph-sddp-jl/115573 "2024-06-14T00:52:04Z")

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Hi everyone, Let’s assume a simple co-optimized expansion and generation problem with 13 nodes: 1 for expansion and 12 generations corresponding to 12 months. There is uncertainty during generation, e.g., monthly water …

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## [SCIP does not accept starting point of nonlinear objective from .nl file](https://discourse.julialang.org/t/scip-does-not-accept-starting-point-of-nonlinear-objective-from-nl-file/115442)

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**Author:** [@Stuart\_Rogers](https://discourse.julialang.org/u/Stuart_Rogers)\
**Replies:** 12\
**Last updated:** [June 13, 2024, 10:49pm UTC](https://discourse.julialang.org/t/scip-does-not-accept-starting-point-of-nonlinear-objective-from-nl-file/115442 "2024-06-13T22:49:34Z")

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I construct a nonlinear model in JuMP using the legacy and non-legacy interfaces, providing the same initial solution, and save the models to .nl files. SCIP is able to solve both .nl files correctly to optimality. SCIP …

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## [Sys.CPU\_THREADS doesn't appear to get all my threads on Mac](https://discourse.julialang.org/t/sys-cpu-threads-doesnt-appear-to-get-all-my-threads-on-mac/115613)

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**Author:** [@schwob](https://discourse.julialang.org/u/schwob)\
**Replies:** 4\
**Last updated:** [June 13, 2024, 6:57pm UTC](https://discourse.julialang.org/t/sys-cpu-threads-doesnt-appear-to-get-all-my-threads-on-mac/115613 "2024-06-13T18:57:10Z")

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On my Mac computer, Sys.CPU\_THREADS=16, but in the terminal, sysctl -n hw.ncpu=24, which really implies I have 48 threads. I’m trying to use Distributed’s addprocs()=addprocs(Sys.CPU\_THREADS) command, but it seems to not…

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## [Has anyone tranlated the TE Process to Julia?](https://discourse.julialang.org/t/has-anyone-tranlated-the-te-process-to-julia/115614)

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**Author:** [@RGonTheNoble](https://discourse.julialang.org/u/RGonTheNoble)\
**Replies:** 0\
**Last updated:** [June 13, 2024, 6:41pm UTC](https://discourse.julialang.org/t/has-anyone-tranlated-the-te-process-to-julia/115614 "2024-06-13T18:41:42Z")

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I remember using a MATLAB-Simulink model for the Tennessee-Eastman (TE) process back in grad school to test some algorithms; and I also remember that using this simulator was a horrible experience. Apparently a lot of pe…

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## [Performance issue with an API calling another API](https://discourse.julialang.org/t/performance-issue-with-an-api-calling-another-api/110976)

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**Author:** [@AbrJA](https://discourse.julialang.org/u/AbrJA)\
**Replies:** 3\
**Last updated:** [June 13, 2024, 4:11pm UTC](https://discourse.julialang.org/t/performance-issue-with-an-api-calling-another-api/110976 "2024-06-13T16:11:52Z")

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Hi everyone, Exploring the Oxygen package to build APIs I found this I haven’t been able to solve When I run this API (with a 150 ms sleep to simulate the time taken by a model): using Oxygen @get "/model" function(…

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## [Errorline like plot for histograms](https://discourse.julialang.org/t/errorline-like-plot-for-histograms/113911)

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**Author:** [@dmetivie](https://discourse.julialang.org/u/dmetivie)\
**Replies:** 6\
**Last updated:** [June 13, 2024, 2:32pm UTC](https://discourse.julialang.org/t/errorline-like-plot-for-histograms/113911 "2024-06-13T14:32:53Z")

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I would like to create an envelope plot for multiple histogram (input as matrix) something like what is done with errorline in StatsPlots. (I did not find a Makie equivalent of errorline). Basically, what I want would l…

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## [Implementation of the COPS benchmark in JuMP](https://discourse.julialang.org/t/implementation-of-the-cops-benchmark-in-jump/115555)

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**Author:** [@frapac](https://discourse.julialang.org/u/frapac)\
**Replies:** 12\
**Last updated:** [June 13, 2024, 11:55am UTC](https://discourse.julialang.org/t/implementation-of-the-cops-benchmark-in-jump/115555 "2024-06-13T11:55:10Z")

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Together with @tmigot , we have re-implemented the COPS benchmark in pure JuMP: GitHub - MadNLP/COPSBenchmark.jl: Implementation of the COPS benchmark with JuMP. The COPS benchmark is a collection of challenging nonline…

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## [Custom loss in DiffEqParamEstim](https://discourse.julialang.org/t/custom-loss-in-diffeqparamestim/115580)

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**Author:** [@Piyush](https://discourse.julialang.org/u/Piyush)\
**Replies:** 3\
**Last updated:** [June 13, 2024, 11:20am UTC](https://discourse.julialang.org/t/custom-loss-in-diffeqparamestim/115580 "2024-06-13T11:20:50Z")

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How to add first differencing term in custom loss function as included in the inbuilt L2Loss function? Is there a way I can access the documentation for the same?

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## [Copy/paste a DataFrame into a PowerPoint table](https://discourse.julialang.org/t/copy-paste-a-dataframe-into-a-powerpoint-table/115570)

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**Author:** [@Datseris](https://discourse.julialang.org/u/Datseris)\
**Replies:** 4\
**Last updated:** [June 13, 2024, 8:09am UTC](https://discourse.julialang.org/t/copy-paste-a-dataframe-into-a-powerpoint-table/115570 "2024-06-13T08:09:20Z")

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I’m looking if anyone in the community have already come with a quick/simple way to just “copy paste” a DataFrame, whose columns are all composed of real numbers, into a PowerPoint table. Would save me tons of time!!! Ex…

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## [Linewidth in data space in GLMakie](https://discourse.julialang.org/t/linewidth-in-data-space-in-glmakie/115502)

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**Author:** [@ohmsweetohm1](https://discourse.julialang.org/u/ohmsweetohm1)\
**Replies:** 5\
**Last updated:** [June 13, 2024, 7:36am UTC](https://discourse.julialang.org/t/linewidth-in-data-space-in-glmakie/115502 "2024-06-13T07:36:03Z")

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How can I make the linewidth of a lines plot be in data space, so that ot changes when scrolling?

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## [Difference between GPUArrays.jl and KernelAbstractations.jl](https://discourse.julialang.org/t/difference-between-gpuarrays-jl-and-kernelabstractations-jl/115457)

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**Author:** [@albertomercurio](https://discourse.julialang.org/u/albertomercurio)\
**Replies:** 4\
**Last updated:** [June 12, 2024, 2:17pm UTC](https://discourse.julialang.org/t/difference-between-gpuarrays-jl-and-kernelabstractations-jl/115457 "2024-06-12T14:17:50Z")

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Hello, I would like to implement some simple matrix-vector multiplication, when none of them are strided arrays (e.g., @view(A\[\[1, 4, 5\], 1:10\])). Standard LinearAlgebra.mul! doesn’t support these arrays, so I thought t…

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## [JuMP - constraint for specific indices](https://discourse.julialang.org/t/jump-constraint-for-specific-indices/115550)

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**Author:** [@priantop](https://discourse.julialang.org/u/priantop)\
**Replies:** 4\
**Last updated:** [June 12, 2024, 2:17pm UTC](https://discourse.julialang.org/t/jump-constraint-for-specific-indices/115550 "2024-06-12T14:17:08Z")

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Hello, I am formulating LP problem using JuMP for energy system one of the constraints is the nodal electricity balance, say I have indices of node, time, and technologies How do I make a certain expression valid for …

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