# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=240

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**Page:** 241

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## [! vs @view for indexing DataFrame](https://discourse.julialang.org/t/vs-view-for-indexing-dataframe/89462)

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**Author:** [@jar1](https://discourse.julialang.org/u/jar1)\
**Replies:** 5\
**Last updated:** [October 29, 2022, 6:34am UTC](https://discourse.julialang.org/t/vs-view-for-indexing-dataframe/89462 "2022-10-29T06:34:02Z")

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What is the difference in purpose between ! and @view for indexing a DataFrame? @bkamins’ indexing blog post says When extracting the data from a data frame if you use ! no copying of data is made. Instead, you just ge…

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## [Implement time out when creating the model](https://discourse.julialang.org/t/implement-time-out-when-creating-the-model/89451)

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**Author:** [@dourouc05](https://discourse.julialang.org/u/dourouc05)\
**Replies:** 3\
**Last updated:** [October 28, 2022, 11:36pm UTC](https://discourse.julialang.org/t/implement-time-out-when-creating-the-model/89451 "2022-10-28T23:36:49Z")

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Hi, I’m comparing several ways of solving the same problem. One of these approaches create extremely large models, so large that @variable(model, variable\[e in edges(graph), d in edges(graph2), v in vertices(graph)\]) ta…

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## [Using simplex method with Mosek with MosekTool package](https://discourse.julialang.org/t/using-simplex-method-with-mosek-with-mosektool-package/89416)

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**Author:** [@Khashayar-Neshat](https://discourse.julialang.org/u/Khashayar-Neshat)\
**Replies:** 2\
**Last updated:** [October 28, 2022, 5:56pm UTC](https://discourse.julialang.org/t/using-simplex-method-with-mosek-with-mosektool-package/89416 "2022-10-28T17:56:31Z")

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Hi, I want to solve a linear programming problem with the SumOfSquare package with Mosek. How can I tell the MosekTool package that Mosek use the simplex method instead of the interior point method?

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## [Joint longitudinal + time-to-event modelling in Julia?](https://discourse.julialang.org/t/joint-longitudinal-time-to-event-modelling-in-julia/89388)

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**Author:** [@danielinteractive](https://discourse.julialang.org/u/danielinteractive)\
**Replies:** 3\
**Last updated:** [October 28, 2022, 8:49am UTC](https://discourse.julialang.org/t/joint-longitudinal-time-to-event-modelling-in-julia/89388 "2022-10-28T08:49:33Z")

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Hi everyone, I am new to Julia, and curious if somebody did any work on joint modelling of longitudinal and time-to-event data already and can share any code examples as starting points for me? Thanks, cheers Daniel

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## [What if \`df.col .= v\` was in-place?](https://discourse.julialang.org/t/what-if-df-col-v-was-in-place/89367)

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**Author:** [@gustafsson](https://discourse.julialang.org/u/gustafsson)\
**Replies:** 10\
**Last updated:** [October 28, 2022, 8:10am UTC](https://discourse.julialang.org/t/what-if-df-col-v-was-in-place/89367 "2022-10-28T08:10:02Z")

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You may or may not be surprised to learn that for a DataFrame .= isn’t always in-place. It surprised me for sure, but I didn’t follow the announcements so that’s on me. What if it was always in-place for existing column…

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## [ModelingToolkit - the concept of "state"](https://discourse.julialang.org/t/modelingtoolkit-the-concept-of-state/89304)

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**Author:** [@BLI](https://discourse.julialang.org/u/BLI)\
**Replies:** 7\
**Last updated:** [October 28, 2022, 8:07am UTC](https://discourse.julialang.org/t/modelingtoolkit-the-concept-of-state/89304 "2022-10-28T08:07:53Z")

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I’m a little confused about the use of the word “state” (not only in ModelingToolkit). In classic dynamic systems theory, the state is the minimum information necessary to describe current time of a dynamic system, so th…

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## [Makie: Colouring 3D Contours by another Array](https://discourse.julialang.org/t/makie-colouring-3d-contours-by-another-array/88829)

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**Author:** [@Whyborn](https://discourse.julialang.org/u/Whyborn)\
**Replies:** 9\
**Last updated:** [October 28, 2022, 7:18am UTC](https://discourse.julialang.org/t/makie-colouring-3d-contours-by-another-array/88829 "2022-10-28T07:18:26Z")

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I would like to build a 3D contour plot, with the contours constructed based on a given array and the colours on said contours defined by a second array. An example relevant to me is the Inviscid Taylor-Green Vortex: us…

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## [Recording an 3d mesh animation, not updating between frames](https://discourse.julialang.org/t/recording-an-3d-mesh-animation-not-updating-between-frames/89428)

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**Author:** [@m\_x155](https://discourse.julialang.org/u/m_x155)\
**Replies:** 1\
**Last updated:** [October 28, 2022, 6:19am UTC](https://discourse.julialang.org/t/recording-an-3d-mesh-animation-not-updating-between-frames/89428 "2022-10-28T06:19:01Z")

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Hi, I have some results from a simulation that represent a 3d surface object moving in time. When I try to record the mesh much like the example in the documentation I don’t seem to get the plot actually updating. It dis…

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## [Flux Chain function](https://discourse.julialang.org/t/flux-chain-function/89369)

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**Author:** [@qwerty](https://discourse.julialang.org/u/qwerty)\
**Replies:** 1\
**Last updated:** [October 27, 2022, 11:12pm UTC](https://discourse.julialang.org/t/flux-chain-function/89369 "2022-10-27T23:12:03Z")

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Why does the Chain function not warn if the output of one layer is not compatible with the imput of the next?

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## [Anyone fetching UUIDs using LibPQ.jl?](https://discourse.julialang.org/t/anyone-fetching-uuids-using-libpq-jl/89395)

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**Author:** [@iamed2](https://discourse.julialang.org/u/iamed2)\
**Replies:** 2\
**Last updated:** [October 27, 2022, 8:40pm UTC](https://discourse.julialang.org/t/anyone-fetching-uuids-using-libpq-jl/89395 "2022-10-27T20:40:26Z")

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I’m introducing support for parsing UUIDs from PostgreSQL in LibPQ.jl and I would like to know if anyone would be negatively impacted by setting UUID as the default type for the PostgreSQL uuid type. This means that if y…

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## [Plots.Surface rescaling gives incorrect color legend](https://discourse.julialang.org/t/plots-surface-rescaling-gives-incorrect-color-legend/89381)

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**Author:** [@Grace\_Chuan](https://discourse.julialang.org/u/Grace_Chuan)\
**Replies:** 1\
**Last updated:** [October 27, 2022, 5:42pm UTC](https://discourse.julialang.org/t/plots-surface-rescaling-gives-incorrect-color-legend/89381 "2022-10-27T17:42:47Z")

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Hello, I am trying to plot a surface via Julia Plots. The maximum of the series I would like to plot along the z axis is 10. But I want the z axis to rescale to (0,20). When I add in the argument: zlim = (0,20), I get wh…

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## [ModelingToolkit.jl ODEProblem throwing error when differential term not isolated to the LHS](https://discourse.julialang.org/t/modelingtoolkit-jl-odeproblem-throwing-error-when-differential-term-not-isolated-to-the-lhs/89365)

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**Author:** [@ap2013](https://discourse.julialang.org/u/ap2013)\
**Replies:** 1\
**Last updated:** [October 27, 2022, 4:36pm UTC](https://discourse.julialang.org/t/modelingtoolkit-jl-odeproblem-throwing-error-when-differential-term-not-isolated-to-the-lhs/89365 "2022-10-27T16:36:59Z")

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I am constructing an ODESystem by connecting 4 different systems. I recently changed one of the systems, I want it to be a 2-DOF planar arm with equations M(\\theta)\\ddot{\\theta} + C(\\theta,\\dot{\\theta})\\dot{\\theta} = u …

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## [Soft constraints in JuMP](https://discourse.julialang.org/t/soft-constraints-in-jump/89373)

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**Author:** [@danielw2904](https://discourse.julialang.org/u/danielw2904)\
**Replies:** 1\
**Last updated:** [October 27, 2022, 4:04pm UTC](https://discourse.julialang.org/t/soft-constraints-in-jump/89373 "2022-10-27T16:04:14Z")

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I am completely new to the JuMP.jl package. I am trying to set soft constraints with different weights but only getting errors for any constraints I set. I would like something similar to this link I have tried using…

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## [Querying an LibSpatialIndex.jl RTree](https://discourse.julialang.org/t/querying-an-libspatialindex-jl-rtree/88916)

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**Author:** [@ctrebbau](https://discourse.julialang.org/u/ctrebbau)\
**Replies:** 2\
**Last updated:** [October 27, 2022, 3:51pm UTC](https://discourse.julialang.org/t/querying-an-libspatialindex-jl-rtree/88916 "2022-10-27T15:51:42Z")

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I have an OpenStreetMapX (mad) of Madrid and around 4 million coordinates that I wish to associate with their corresponding mad.nodes. Unfortunately using OpenStreetMapX.jl’s point\_to\_nodes out-of-the-box is infeasible …

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## [SDP Sum of Squares optimization](https://discourse.julialang.org/t/sdp-sum-of-squares-optimization/88487)

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**Author:** [@parf](https://discourse.julialang.org/u/parf)\
**Replies:** 10\
**Last updated:** [October 27, 2022, 1:45pm UTC](https://discourse.julialang.org/t/sdp-sum-of-squares-optimization/88487 "2022-10-27T13:45:08Z")

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I am trying to solve the following optimization problem: using DynamicPolynomials using SumOfSquares using SDPAFamily χ=1.0 @polyvar x1 x2 x3 x4 f = \[2\*x1\*x4 - 2\*x2\*x3 - x1, -2\*x1\*x3 - 2\*x2\*x4 - x2, 2\*x1\*x2,…

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## [Drawing arrows on axes](https://discourse.julialang.org/t/drawing-arrows-on-axes/30341)

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**Author:** [@squirrel](https://discourse.julialang.org/u/squirrel)\
**Replies:** 9\
**Last updated:** [October 27, 2022, 12:35pm UTC](https://discourse.julialang.org/t/drawing-arrows-on-axes/30341 "2022-10-27T12:35:26Z")

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I’m trying to add arrows to my axes, but it isn’t working. I have using Plots x(u) = u y(u) = sqrt(u) y2(u) = -sqrt(u) plot(x, \[y, y2\], 0, 5, framestyle = :origin, legend = :none, linecolor = :blue, dr…

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## [ODE terms dependent on time of events](https://discourse.julialang.org/t/ode-terms-dependent-on-time-of-events/88962)

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**Author:** [@KalelR](https://discourse.julialang.org/u/KalelR)\
**Replies:** 5\
**Last updated:** [October 27, 2022, 10:13am UTC](https://discourse.julialang.org/t/ode-terms-dependent-on-time-of-events/88962 "2022-10-27T10:13:26Z")

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Hey there I would like some advice for implementing efficient code for a spiking neuron network with coupling that depends on spike times. When a neuron in the model spikes (one of its variables, the membrane potential,…

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## [Change default resolution in Theme() and Mac retina displays](https://discourse.julialang.org/t/change-default-resolution-in-theme-and-mac-retina-displays/89345)

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**Author:** [@garrek](https://discourse.julialang.org/u/garrek)\
**Replies:** 2\
**Last updated:** [October 27, 2022, 6:24am UTC](https://discourse.julialang.org/t/change-default-resolution-in-theme-and-mac-retina-displays/89345 "2022-10-27T06:24:22Z")

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Is there a way to set the default resolution in a Theme() in Makie? I want to set a default theme for Retina displays on Mac, since everything is too small with the default. I can set font size, line width, etc., but can…

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## [Translating a basic MNIST tensorflow network into an MLJFlux builder](https://discourse.julialang.org/t/translating-a-basic-mnist-tensorflow-network-into-an-mljflux-builder/89338)

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**Author:** [@ablaom](https://discourse.julialang.org/u/ablaom)\
**Replies:** 1\
**Last updated:** [October 27, 2022, 12:08am UTC](https://discourse.julialang.org/t/translating-a-basic-mnist-tensorflow-network-into-an-mljflux-builder/89338 "2022-10-27T00:08:20Z")

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On slack I have been asked: How does one translate the following into MLJFlux. The code is from this tensorflow tutorial on the MNIST dataset for beginners. model = tf.keras.models.Sequential(\[ tf.keras.layers.Flat…

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## [Polyhedron of JuMP model with Polyhedra or Lazyset](https://discourse.julialang.org/t/polyhedron-of-jump-model-with-polyhedra-or-lazyset/89218)

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**Author:** [@papar](https://discourse.julialang.org/u/papar)\
**Replies:** 7\
**Last updated:** [October 26, 2022, 10:53pm UTC](https://discourse.julialang.org/t/polyhedron-of-jump-model-with-polyhedra-or-lazyset/89218 "2022-10-26T22:53:48Z")

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Hello, I want to plot a 3D polyhedron of a JuMP model for education purposes. I have seen these packages Polyhedra and LazySets, but I am unsure how to convert a JuMP model. I believe it requires projection/elimination.…

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## [Diffeq ContinuousCallback "not callable" errors](https://discourse.julialang.org/t/diffeq-continuouscallback-not-callable-errors/88198)

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**Author:** [@John\_Boik](https://discourse.julialang.org/u/John_Boik)\
**Replies:** 9\
**Last updated:** [October 26, 2022, 7:42pm UTC](https://discourse.julialang.org/t/diffeq-continuouscallback-not-callable-errors/88198 "2022-10-26T19:42:36Z")

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My use of ContinuousCallback from DifferentialEquations.jl is throwing an error and I don’t know why. Any help would be appreciated. The short version of the error is: LoadError: MethodError: objects of type SciMLBase.C…

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## [ModelingToolkit - component defaults](https://discourse.julialang.org/t/modelingtoolkit-component-defaults/89281)

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**Author:** [@BLI](https://discourse.julialang.org/u/BLI)\
**Replies:** 4\
**Last updated:** [October 26, 2022, 3:54pm UTC](https://discourse.julialang.org/t/modelingtoolkit-component-defaults/89281 "2022-10-26T15:54:18Z")

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I have some background with Modelica, where the specification and modification of defaults is relatively simple. From the ModelingToolkit documentation \[p. 2 of ModelingToolkit.jl documentation\]: Often it is a good ide…

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## [JumpProcesses.jl : Specify the specific jumps which occured](https://discourse.julialang.org/t/jumpprocesses-jl-specify-the-specific-jumps-which-occured/89291)

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**Author:** [@ashwingop](https://discourse.julialang.org/u/ashwingop)\
**Replies:** 5\
**Last updated:** [October 26, 2022, 12:53pm UTC](https://discourse.julialang.org/t/jumpprocesses-jl-specify-the-specific-jumps-which-occured/89291 "2022-10-26T12:53:54Z")

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Hey all, I am working with a Markov jump process with multiple possible reactions (Variable rates) coupled to a stochastic differential equation. I am trying to simulate it using the JumpProcesses.jl package. I am tryi…

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## [Print JuMP model in IJulia in plain text (i.e. non-LaTeX)](https://discourse.julialang.org/t/print-jump-model-in-ijulia-in-plain-text-i-e-non-latex/89276)

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**Author:** [@fleimgruber](https://discourse.julialang.org/u/fleimgruber)\
**Replies:** 4\
**Last updated:** [October 26, 2022, 9:07am UTC](https://discourse.julialang.org/t/print-jump-model-in-ijulia-in-plain-text-i-e-non-latex/89276 "2022-10-26T09:07:57Z")

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I want to use JuMP with the IJulia server, but in a reduced editing environment, i.e. not inside a browser. For this reason I want a call to print(model) to print in plain text instead of LaTeX. I found (old) code exampl…

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## [Nonlinear activation functions (and Transformers) on the way out?! And "SimpleGate" the replacement](https://discourse.julialang.org/t/nonlinear-activation-functions-and-transformers-on-the-way-out-and-simplegate-the-replacement/80127)

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**Author:** [@Palli](https://discourse.julialang.org/u/Palli)\
**Replies:** 1\
**Last updated:** [October 26, 2022, 8:23am UTC](https://discourse.julialang.org/t/nonlinear-activation-functions-and-transformers-on-the-way-out-and-simplegate-the-replacement/80127 "2022-10-26T08:23:53Z")

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our SimpleGate could be implemented by an element-wise multiplication, that’s all: SimpleGate(X, Y) = X ⊙ Y where X and Y are feature maps of the same size. What caught my eye first was: https://arxiv.org/pdf/2204…

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## [Arrows not working on log-log plot (GR)](https://discourse.julialang.org/t/arrows-not-working-on-log-log-plot-gr/61454)

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**Author:** [@white-c](https://discourse.julialang.org/u/white-c)\
**Replies:** 5\
**Last updated:** [October 26, 2022, 6:10am UTC](https://discourse.julialang.org/t/arrows-not-working-on-log-log-plot-gr/61454 "2022-10-26T06:10:04Z")

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If I run code like this, the plot doesn’t work correctly when I use the arrows. Any suggestions to fix this? using Plots gr() plot( \[0.1, 10\], \[0.1, 10\], xscale=:log10, yscale=:log10, xlims=(0.01, 100), …

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## [Optimising an imperfect, high-dimensional simulation with experimental data](https://discourse.julialang.org/t/optimising-an-imperfect-high-dimensional-simulation-with-experimental-data/89234)

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**Author:** [@duncan](https://discourse.julialang.org/u/duncan)\
**Replies:** 6\
**Last updated:** [October 26, 2022, 12:00am UTC](https://discourse.julialang.org/t/optimising-an-imperfect-high-dimensional-simulation-with-experimental-data/89234 "2022-10-26T00:00:15Z")

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I have used data from CFD simulations to create a Gaussian process surrogate of a mixing tank. The GP can estimate the reaction rate of the tank given a subset of the operating conditions, e.g. reagent concentration and …

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## [How can I specify a vector of coupled ODEs symbolically (for use in ModelingToolkit)?](https://discourse.julialang.org/t/how-can-i-specify-a-vector-of-coupled-odes-symbolically-for-use-in-modelingtoolkit/89211)

<div class="topic-metadata">

**Author:** [@yohan](https://discourse.julialang.org/u/yohan)\
**Replies:** 2\
**Last updated:** [October 25, 2022, 8:20pm UTC](https://discourse.julialang.org/t/how-can-i-specify-a-vector-of-coupled-odes-symbolically-for-use-in-modelingtoolkit/89211 "2022-10-25T20:20:38Z")

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I am new to Julia and trying to learn ModelingToolkit. I have looked at the tutorials and they are bit simpler than the use case I have: I would like to implement coupled ODEs for a firing rate-based neuronal network mod…

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## [MCMC Benchmark](https://discourse.julialang.org/t/mcmc-benchmark/63013)

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**Author:** [@mschauer](https://discourse.julialang.org/u/mschauer)\
**Replies:** 14\
**Last updated:** [October 25, 2022, 2:48pm UTC](https://discourse.julialang.org/t/mcmc-benchmark/63013 "2022-10-25T14:48:52Z")

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In MCMC there is always the issue that there are no established benchmarks. C.f. for example machine learning - Performance benchmarks for MCMC - Cross Validated . There are some related efforts in the community, e.g…

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## [Images.jl loading image produces artifact](https://discourse.julialang.org/t/images-jl-loading-image-produces-artifact/89249)

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**Author:** [@TheLateKronos](https://discourse.julialang.org/u/TheLateKronos)\
**Replies:** 4\
**Last updated:** [October 25, 2022, 2:47pm UTC](https://discourse.julialang.org/t/images-jl-loading-image-produces-artifact/89249 "2022-10-25T14:47:13Z")

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I have made an issue (Images.jl issue 1017), but here is a copy of the text in case I can get help faster and/or make a more googlable resource for this problem: The original image looks like this: I then load the i…

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