# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=172

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**Page:** 173

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## [Model building problem](https://discourse.julialang.org/t/model-building-problem/102783)

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**Author:** [@jack\_lee](https://discourse.julialang.org/u/jack_lee)\
**Replies:** 13\
**Last updated:** [August 15, 2023, 7:27am UTC](https://discourse.julialang.org/t/model-building-problem/102783 "2023-08-15T07:27:32Z")

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The target of a survey is set as business people and college students, requirements: The total number is 600,and student is not less than 250; the way of survey includes questionnaire and phone, the number is questionn…

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## [Compute intensive function rewrite](https://discourse.julialang.org/t/compute-intensive-function-rewrite/102809)

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**Author:** [@BioinfoBuggaBoo](https://discourse.julialang.org/u/BioinfoBuggaBoo)\
**Replies:** 2\
**Last updated:** [August 15, 2023, 5:08am UTC](https://discourse.julialang.org/t/compute-intensive-function-rewrite/102809 "2023-08-15T05:08:50Z")

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I have been using a package in R that really only has one main function which does a lot behind the scenes of which a portion is prohibitively slow to the point where the timescales involved are far too long to ever achi…

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## [Creating a PSDCone Constraint in COSMO](https://discourse.julialang.org/t/creating-a-psdcone-constraint-in-cosmo/102749)

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**Author:** [@fimiller](https://discourse.julialang.org/u/fimiller)\
**Replies:** 7\
**Last updated:** [August 14, 2023, 8:29pm UTC](https://discourse.julialang.org/t/creating-a-psdcone-constraint-in-cosmo/102749 "2023-08-14T20:29:28Z")

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Due to memory limitation issues, I am unable to use JuMP to create variables and the model I would like to use. As such, I am trying to use COSMO directly. I am trying to create a PSDCone constraint of the form (A - dia…

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## [Sqrt of QuadExpr](https://discourse.julialang.org/t/sqrt-of-quadexpr/102797)

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**Author:** [@i9e1](https://discourse.julialang.org/u/i9e1)\
**Replies:** 2\
**Last updated:** [August 14, 2023, 7:45pm UTC](https://discourse.julialang.org/t/sqrt-of-quadexpr/102797 "2023-08-14T19:45:21Z")

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Hi there, Do you think sqrt of special cases of QuadExpr is useful or dangerous? Currrently the user gets a warning when using the unsupported nonlinear operator sqrt and has to do manual reformulation (where possible)…

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## [Numerical simulation changes with different tspan](https://discourse.julialang.org/t/numerical-simulation-changes-with-different-tspan/102726)

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**Author:** [@Yoni\_Maltsman](https://discourse.julialang.org/u/Yoni_Maltsman)\
**Replies:** 4\
**Last updated:** [August 14, 2023, 5:54pm UTC](https://discourse.julialang.org/t/numerical-simulation-changes-with-different-tspan/102726 "2023-08-14T17:54:37Z")

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I am attempting to simulate a network of four neurons, where the ith neuron’s dynamics are described by the following differential equations: \\dot{V}\_m = I\_{syn} - (V\_m - \\alpha\_f^-\\tanh(V\_m - \\delta\_f^-) + \\alpha\_s^+…

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## [Finding root numerically for a function defined in a finite range](https://discourse.julialang.org/t/finding-root-numerically-for-a-function-defined-in-a-finite-range/102729)

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**Author:** [@roi.holtzman](https://discourse.julialang.org/u/roi.holtzman)\
**Replies:** 16\
**Last updated:** [August 14, 2023, 5:28pm UTC](https://discourse.julialang.org/t/finding-root-numerically-for-a-function-defined-in-a-finite-range/102729 "2023-08-14T17:28:23Z")

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I have a function f(x) defined in range (-a, \\infty). f(x) is actually a piecewise function f\_1(x) for (-a,0), and f\_2(x) for (0, \\infty). For these two functions f\_1, f\_2 the 2nd derivative diverges at the boundary x=0.…

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## [HTTP communication between RPI and computer via an Ethernet cable](https://discourse.julialang.org/t/http-communication-between-rpi-and-computer-via-an-ethernet-cable/102683)

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**Author:** [@yakir12](https://discourse.julialang.org/u/yakir12)\
**Replies:** 6\
**Last updated:** [August 14, 2023, 4:10pm UTC](https://discourse.julialang.org/t/http-communication-between-rpi-and-computer-via-an-ethernet-cable/102683 "2023-08-14T16:10:45Z")

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I want to have a Raspberry Pi and a PC that are connected with an Ethernet cable to communicate with each other via a server-client-HTTP.jl setup. I don’t know however what IP address I should use, or any additional step…

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## [lme4::lmList equivalent in Julia](https://discourse.julialang.org/t/lme4-lmlist-equivalent-in-julia/102670)

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**Author:** [@lindemann09](https://discourse.julialang.org/u/lindemann09)\
**Replies:** 2\
**Last updated:** [August 14, 2023, 10:23am UTC](https://discourse.julialang.org/t/lme4-lmlist-equivalent-in-julia/102670 "2023-08-14T10:23:43Z")

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The lme4 package in R has the function lmList, which I use heavily to examine shrinkage in mixed-models. MixedModels.jl does not seem to have the function. MixedModelsMakie.jl is great to visualize shrinkage, but it doe…

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## [JuliaData BoF @ JuliaCon2023 discussion](https://discourse.julialang.org/t/juliadata-bof-juliacon2023-discussion/102521)

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**Author:** [@bkamins](https://discourse.julialang.org/u/bkamins)\
**Replies:** 2\
**Last updated:** [August 14, 2023, 2:05am UTC](https://discourse.julialang.org/t/juliadata-bof-juliacon2023-discussion/102521 "2023-08-14T02:05:10Z")

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Below I recap a summary from the BoF Data Ecosystem discussion during JuliaCon2023 (for sure, it is probably opinionated, so feel free to comment to add your thoughts). I recap things I took out as most important to wor…

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## [How to properly work with changing precision in ArbNumerics](https://discourse.julialang.org/t/how-to-properly-work-with-changing-precision-in-arbnumerics/102775)

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**Author:** [@roi.holtzman](https://discourse.julialang.org/u/roi.holtzman)\
**Replies:** 2\
**Last updated:** [August 13, 2023, 9:03pm UTC](https://discourse.julialang.org/t/how-to-properly-work-with-changing-precision-in-arbnumerics/102775 "2023-08-13T21:03:17Z")

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I do not understand how I should properly work with ArbNumerics. I tried setting the number of digits at the beginning of my code, so that later I easily change the number of digits for all of my variables. digits = 20…

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## [Multi-threaded calls to CUDA matrix multiplication](https://discourse.julialang.org/t/multi-threaded-calls-to-cuda-matrix-multiplication/102753)

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**Author:** [@eveningsilverfox](https://discourse.julialang.org/u/eveningsilverfox)\
**Replies:** 5\
**Last updated:** [August 13, 2023, 5:58pm UTC](https://discourse.julialang.org/t/multi-threaded-calls-to-cuda-matrix-multiplication/102753 "2023-08-13T17:58:04Z")

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I am trying to call CUDA matrix multiplication using a multi-threaded for loop, but I am getting an error (Initialising Julia with julia -t8). My cpu has 8 cores (16 threads), and my GPU is NVIDIA GeForce GTX 1650 with 1…

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## [Create a (Di)graph from an iterator over edges with a certain number of vertices](https://discourse.julialang.org/t/create-a-di-graph-from-an-iterator-over-edges-with-a-certain-number-of-vertices/102751)

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**Author:** [@Torkel](https://discourse.julialang.org/u/Torkel)\
**Replies:** 2\
**Last updated:** [August 13, 2023, 3:20pm UTC](https://discourse.julialang.org/t/create-a-di-graph-from-an-iterator-over-edges-with-a-certain-number-of-vertices/102751 "2023-08-13T15:20:02Z")

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Given that I have a set of edges, e.g: using Graphs g = Graphs.grid(\[5, 5\]) es = edges(g) How do I create a new Graph, using those edges, but wit ha specific number of vertices? In this case I can do: SimpleDiGraphFro…

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## [Displaying images with text](https://discourse.julialang.org/t/displaying-images-with-text/102694)

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**Author:** [@cpfiffer](https://discourse.julialang.org/u/cpfiffer)\
**Replies:** 16\
**Last updated:** [August 12, 2023, 11:35pm UTC](https://discourse.julialang.org/t/displaying-images-with-text/102694 "2023-08-12T23:35:22Z")

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I’m working on adapting the fast.ai fastbook with a few other people. You can find our work slowly happening via our website or by the Quarto book here. As part of this, I want to build a little tool to view images with…

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## [Reading LIBSVM format](https://discourse.julialang.org/t/reading-libsvm-format/99466)

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**Author:** [@ymalitsky](https://discourse.julialang.org/u/ymalitsky)\
**Replies:** 3\
**Last updated:** [August 12, 2023, 6:59pm UTC](https://discourse.julialang.org/t/reading-libsvm-format/99466 "2023-08-12T18:59:30Z")

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Hi! How one can read files in the libsvm format in Julia? The LIBSVM.jl package seems to implement only algorithms. My current solution would be to read the file in python, save it in other format and then load it into J…

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## [Simple approachable example highlighting the usage of a stiff ODE solver in DiffEq](https://discourse.julialang.org/t/simple-approachable-example-highlighting-the-usage-of-a-stiff-ode-solver-in-diffeq/102741)

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**Author:** [@Datseris](https://discourse.julialang.org/u/Datseris)\
**Replies:** 8\
**Last updated:** [August 12, 2023, 5:15pm UTC](https://discourse.julialang.org/t/simple-approachable-example-highlighting-the-usage-of-a-stiff-ode-solver-in-diffeq/102741 "2023-08-12T17:15:13Z")

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Hi all, I will be presenting a Julia tutorial on an international PHD school, and OrdinaryDiffEq.jl will be one of the packages I will be highlighting. I want to demonstrate some of the various solvers of the ecosystem v…

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## [Problem with small integrals](https://discourse.julialang.org/t/problem-with-small-integrals/101634)

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**Author:** [@Ross\_Boylan](https://discourse.julialang.org/u/Ross_Boylan)\
**Replies:** 19\
**Last updated:** [August 12, 2023, 12:39pm UTC](https://discourse.julialang.org/t/problem-with-small-integrals/101634 "2023-08-12T12:39:02Z")

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I am computing 2 integrals over the real line using quadgk from the package of the same name. The goal is to estimate the ratio of the integrals. Often both integrals are quite small, especially in some extreme cases I’…

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## [Individual ctivation function for each network output](https://discourse.julialang.org/t/individual-ctivation-function-for-each-network-output/102676)

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**Author:** [@tommy\_J](https://discourse.julialang.org/u/tommy_J)\
**Replies:** 1\
**Last updated:** [August 11, 2023, 8:38pm UTC](https://discourse.julialang.org/t/individual-ctivation-function-for-each-network-output/102676 "2023-08-11T20:38:19Z")

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Hi, Can I use a different activation function for each output of my network? using Lux net = Chain(Dense(3, 10, tanh), Dense(10, 3, tanh)) I know that output 2 can only be positive, but 1 and 3 can be negative. Is i…

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## [ModelingToolkit KeyError](https://discourse.julialang.org/t/modelingtoolkit-keyerror/102716)

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**Author:** [@sabbraxcaddabra](https://discourse.julialang.org/u/sabbraxcaddabra)\
**Replies:** 4\
**Last updated:** [August 11, 2023, 6:38pm UTC](https://discourse.julialang.org/t/modelingtoolkit-keyerror/102716 "2023-08-11T18:38:27Z")

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I’m trying to model powder burning in small chamber by the following code. The problem is that I need to stop integration when there is more gas then chamber volume. I try to do it by adding callback to bal\_eqs. But I g…

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## [Extreme ray values unbounded LP JuMP](https://discourse.julialang.org/t/extreme-ray-values-unbounded-lp-jump/102686)

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**Author:** [@bcoulier](https://discourse.julialang.org/u/bcoulier)\
**Replies:** 5\
**Last updated:** [August 11, 2023, 12:56pm UTC](https://discourse.julialang.org/t/extreme-ray-values-unbounded-lp-jump/102686 "2023-08-11T12:56:39Z")

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I’m currently dealing with an LP problem where the solution to the primal turns out to be infeasible, leading to an unbounded dual. In order to create a feasibility cut, I’m aiming to acquire the extreme ray values from …

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## [Remove column having missing values and assign default names again](https://discourse.julialang.org/t/remove-column-having-missing-values-and-assign-default-names-again/102666)

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**Author:** [@raman\_kumar](https://discourse.julialang.org/u/raman_kumar)\
**Replies:** 7\
**Last updated:** [August 11, 2023, 10:01am UTC](https://discourse.julialang.org/t/remove-column-having-missing-values-and-assign-default-names-again/102666 "2023-08-11T10:01:31Z")

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I have a dataframe having default(not given) column names :heavy\_minus\_sign:Column1 Column2 Column3 . and after removing Column containing missing values using df=df\[!, Not(all.(ismissing, eachcol(df)))\] it looks li…

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## [Possibility to store outcome of \`ForwardDiff.jacobian\` already in sparse format](https://discourse.julialang.org/t/possibility-to-store-outcome-of-forwarddiff-jacobian-already-in-sparse-format/102635)

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**Author:** [@DanDoe](https://discourse.julialang.org/u/DanDoe)\
**Replies:** 2\
**Last updated:** [August 11, 2023, 6:19am UTC](https://discourse.julialang.org/t/possibility-to-store-outcome-of-forwarddiff-jacobian-already-in-sparse-format/102635 "2023-08-11T06:19:00Z")

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I use ForwardDiff.jacobian in the following way: function \_jacobian\_ad\_forward(p, t0, u0\_ode, du\_ode, config) J = ForwardDiff.jacobian(du\_ode, u0\_ode, config) do du\_ode, u\_ode f!(du\_ode, u\_ode, p, t0) en…

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## [How to set JuMP.jl timeout?](https://discourse.julialang.org/t/how-to-set-jump-jl-timeout/102701)

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**Author:** [@peng](https://discourse.julialang.org/u/peng)\
**Replies:** 2\
**Last updated:** [August 11, 2023, 6:15am UTC](https://discourse.julialang.org/t/how-to-set-jump-jl-timeout/102701 "2023-08-11T06:15:33Z")

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Does anybody know how to set timeout for JuMP.jl? I used JuMP for some optimization problems, but sometime it falls in long time computation. I hope the calculation time is explicitly limited even though a exception is …

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## [CSC to CSR Transformation in GPU](https://discourse.julialang.org/t/csc-to-csr-transformation-in-gpu/102697)

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**Author:** [@A\_M](https://discourse.julialang.org/u/A_M)\
**Replies:** 2\
**Last updated:** [August 10, 2023, 11:21pm UTC](https://discourse.julialang.org/t/csc-to-csr-transformation-in-gpu/102697 "2023-08-10T23:21:28Z")

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Is there any way to transfer A in CSC to CSR in CUDA using Adjoint? n\_rows = 1000000 n\_cols = 1000000 nnz = 10000000 row\_indices = rand(1:n\_rows, nnz) col\_indices = rand(1:n\_cols, nnz) values = rand(nnz) A = spars…

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## [InexactError in Callback](https://discourse.julialang.org/t/inexacterror-in-callback/102648)

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**Author:** [@jack\_lee](https://discourse.julialang.org/u/jack_lee)\
**Replies:** 2\
**Last updated:** [August 10, 2023, 8:49pm UTC](https://discourse.julialang.org/t/inexacterror-in-callback/102648 "2023-08-10T20:49:23Z")

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When I learn the user-cut callback function ,I rewrite the code below: function user\_cut() Random.seed!(13) N = 30 capacity = 10 weights,values = rand(N),rand(N) model = Model(GLPK.Optimizer) @va…

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## [How to structure Bayesian model for hiring data based on race, performance, and years of experience](https://discourse.julialang.org/t/how-to-structure-bayesian-model-for-hiring-data-based-on-race-performance-and-years-of-experience/102655)

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**Author:** [@mthelm85](https://discourse.julialang.org/u/mthelm85)\
**Replies:** 2\
**Last updated:** [August 10, 2023, 1:08pm UTC](https://discourse.julialang.org/t/how-to-structure-bayesian-model-for-hiring-data-based-on-race-performance-and-years-of-experience/102655 "2023-08-10T13:08:01Z")

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I’m working on an analysis of some HR data that is attempting to answer the following question: Do applicants of different races have substantially different probabilities of being selected? For now, I’m focusing on a …

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## [How to create circular color gradient plot?](https://discourse.julialang.org/t/how-to-create-circular-color-gradient-plot/102301)

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**Author:** [@vladdez](https://discourse.julialang.org/u/vladdez)\
**Replies:** 6\
**Last updated:** [August 1, 2023, 11:55am UTC](https://discourse.julialang.org/t/how-to-create-circular-color-gradient-plot/102301 "2023-08-01T11:55:57Z")

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I see a lot of examples how to do it in Python, but no example how to do it in Julia Makie. What should I use, mash?

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## [How to utilize symmetry in tensor contraction?](https://discourse.julialang.org/t/how-to-utilize-symmetry-in-tensor-contraction/102514)

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**Author:** [@Nellatur](https://discourse.julialang.org/u/Nellatur)\
**Replies:** 2\
**Last updated:** [August 10, 2023, 6:13am UTC](https://discourse.julialang.org/t/how-to-utilize-symmetry-in-tensor-contraction/102514 "2023-08-10T06:13:33Z")

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Hi, I tried to consider tensor contraction A\[a,b\] B\[b,c,d,e\] = C\[a,c,c,e\], where B\[b,c,d,e\] = B\[b,c,e,d\]. I am not sure if my following julia code is right using LinearAlgebra using BenchmarkTools, TensorOperations n …

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## [GLTF + Julia (and Makie)](https://discourse.julialang.org/t/gltf-julia-and-makie/102642)

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**Author:** [@airpmb](https://discourse.julialang.org/u/airpmb)\
**Replies:** 2\
**Last updated:** [August 9, 2023, 5:39pm UTC](https://discourse.julialang.org/t/gltf-julia-and-makie/102642 "2023-08-09T17:39:06Z")

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Is anyone aware of any work out there where GLTF files are used with Julia? I’m aware of GLTF.jl which seems to be the ticket for loading the data, though its most recent commit was in 2021 which makes me a bit wary. My …

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## [Help with callbacks (to set a variable to a constant value)](https://discourse.julialang.org/t/help-with-callbacks-to-set-a-variable-to-a-constant-value/102634)

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**Author:** [@aleppersico](https://discourse.julialang.org/u/aleppersico)\
**Replies:** 4\
**Last updated:** [August 9, 2023, 5:03pm UTC](https://discourse.julialang.org/t/help-with-callbacks-to-set-a-variable-to-a-constant-value/102634 "2023-08-09T17:03:09Z")

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Hello! :slight\_smile: I am simulating a complex dynamical system with DifferentialEquations.jl and via callbacks I introduce perturbations of some parameters. I would like to introduce a callback which continuously sets…

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## [Plots in the terminal (with sixel)](https://discourse.julialang.org/t/plots-in-the-terminal-with-sixel/22503)

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**Author:** [@Alexander-Barth](https://discourse.julialang.org/u/Alexander-Barth)\
**Replies:** 50\
**Last updated:** [August 9, 2023, 4:25pm UTC](https://discourse.julialang.org/t/plots-in-the-terminal-with-sixel/22503 "2023-08-09T16:25:58Z")

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I just came across “sixel” which allows to show graphics in the terminal (while reading this GitHub - csdvrx/sixel-gnuplot: GNUplot with sixel support ) Unfortunately, gnome-terminal does not support this (Bug 729204 –…

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