# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=43

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**Page:** 44

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## [How to think about the cost of vJ and Jv (pullback and pushforward)](https://discourse.julialang.org/t/how-to-think-about-the-cost-of-vj-and-jv-pullback-and-pushforward/129021)

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**Author:** [@Tamas\_Papp](https://discourse.julialang.org/u/Tamas_Papp)\
**Replies:** 6\
**Last updated:** [May 15, 2025, 8:58am UTC](https://discourse.julialang.org/t/how-to-think-about-the-cost-of-vj-and-jv-pullback-and-pushforward/129021 "2025-05-15T08:58:49Z")

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In a calculation involving an f: R^n \\to R^m function, where n ranges from 50 to a few hundred and m \\ge n with a similar scale, I have the option of either calculating the Jacobian J once and saving it, or calcula…

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## [Why convergence behavior of SDDiP algorithm is different with different mixed-integer programming solvers?](https://discourse.julialang.org/t/why-convergence-behavior-of-sddip-algorithm-is-different-with-different-mixed-integer-programming-solvers/128913)

<div class="topic-metadata">

**Author:** [@Engr\_Moiz\_Ahmad](https://discourse.julialang.org/u/Engr_Moiz_Ahmad)\
**Replies:** 11\
**Last updated:** [May 15, 2025, 1:45am UTC](https://discourse.julialang.org/t/why-convergence-behavior-of-sddip-algorithm-is-different-with-different-mixed-integer-programming-solvers/128913 "2025-05-15T01:45:49Z")

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I am dealing with a multi-stage mixed-integer stochastic global supply chain optimization problem and want to solve it using the SDDiP algorithm using the SDDP.jl package in Julia. In this regard, I tried various mixed-…

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## [Reusing NoiseProcess in StochasticDiffEq](https://discourse.julialang.org/t/reusing-noiseprocess-in-stochasticdiffeq/128947)

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**Author:** [@ymuv1](https://discourse.julialang.org/u/ymuv1)\
**Replies:** 2\
**Last updated:** [May 14, 2025, 9:33am UTC](https://discourse.julialang.org/t/reusing-noiseprocess-in-stochasticdiffeq/128947 "2025-05-14T09:33:13Z")

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I am trying to use the same NoiseProcess in two different SDE integrations. I don’t mean to just use the same type of noise, but the same values as well (and potentially values in intermediate times obtained via the brid…

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## [Gurobi12 reports OPTIMAL to an NLP which is actually UNbounded](https://discourse.julialang.org/t/gurobi12-reports-optimal-to-an-nlp-which-is-actually-unbounded/127293)

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**Author:** [@WalterMadelim](https://discourse.julialang.org/u/WalterMadelim)\
**Replies:** 9\
**Last updated:** [May 14, 2025, 1:07am UTC](https://discourse.julialang.org/t/gurobi12-reports-optimal-to-an-nlp-which-is-actually-unbounded/127293 "2025-05-14T01:07:05Z")

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Continuing the discussion from Gurobi12 Reports unbounded to a nonconvex QP which is actually bounded: import JuMP, Gurobi NLP = JuMP.Model(Gurobi.Optimizer); JuMP.@variable(NLP, x); JuMP.@objective(NLP, Min, (x + 1) \* …

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## [Gurobi12 Reports unbounded to a nonconvex QP which is actually bounded](https://discourse.julialang.org/t/gurobi12-reports-unbounded-to-a-nonconvex-qp-which-is-actually-bounded/126657)

<div class="topic-metadata">

**Author:** [@WalterMadelim](https://discourse.julialang.org/u/WalterMadelim)\
**Replies:** 15\
**Last updated:** [May 14, 2025, 1:03am UTC](https://discourse.julialang.org/t/gurobi12-reports-unbounded-to-a-nonconvex-qp-which-is-actually-bounded/126657 "2025-05-14T01:03:45Z")

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import JuMP import Gurobi function objf(x, y) return (y - 2)^2/4 - x \* y end B = JuMP.Model(() -\> Gurobi.Optimizer()); # A bilinear program JuMP.@variable(B, 0 \<= x \<= 1); JuMP.@variable(B, y); # this variable is free Ju…

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## [GPU is slower than CPU for findall on a CuArray](https://discourse.julialang.org/t/gpu-is-slower-than-cpu-for-findall-on-a-cuarray/128916)

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**Author:** [@jtoledom](https://discourse.julialang.org/u/jtoledom)\
**Replies:** 2\
**Last updated:** [May 14, 2025, 12:02am UTC](https://discourse.julialang.org/t/gpu-is-slower-than-cpu-for-findall-on-a-cuarray/128916 "2025-05-14T00:02:17Z")

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I’m writing a code to generate Von Mises random numbers based on this method which is free of accept/reject. It is based on this paper. This issue appears to be with findall. Anyone can reproduce the behaviour by using…

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## [Optimizing the computation of jacobians for multiple shooting implementation](https://discourse.julialang.org/t/optimizing-the-computation-of-jacobians-for-multiple-shooting-implementation/128976)

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**Author:** [@jackyarndley](https://discourse.julialang.org/u/jackyarndley)\
**Replies:** 10\
**Last updated:** [May 13, 2025, 9:38pm UTC](https://discourse.julialang.org/t/optimizing-the-computation-of-jacobians-for-multiple-shooting-implementation/128976 "2025-05-13T21:38:36Z")

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Hi, I’ve been working with multiple shooting for trajectory optimization. I am currently using the sparse backend from DifferentiationInterface.jl and using DifferentialEquations.jl to perform the integration. A snippet …

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## [In a Plots.jl \`bar\` plot, how to remove space between bars?](https://discourse.julialang.org/t/in-a-plots-jl-bar-plot-how-to-remove-space-between-bars/128933)

<div class="topic-metadata">

**Author:** [@Torkel](https://discourse.julialang.org/u/Torkel)\
**Replies:** 2\
**Last updated:** [May 13, 2025, 10:18am UTC](https://discourse.julialang.org/t/in-a-plots-jl-bar-plot-how-to-remove-space-between-bars/128933 "2025-05-13T10:18:20Z")

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Here: using Plots vals = \[1.0 + rand() for \_ in 1:10\] bar(vals) How do I remove the space between the bars (and make them be tight)?

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## [Fail to re-add new constraints as a new upper bound of an expression in JuMP model](https://discourse.julialang.org/t/fail-to-re-add-new-constraints-as-a-new-upper-bound-of-an-expression-in-jump-model/128850)

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**Author:** [@Wendy\_Weng](https://discourse.julialang.org/u/Wendy_Weng)\
**Replies:** 2\
**Last updated:** [May 12, 2025, 8:39pm UTC](https://discourse.julialang.org/t/fail-to-re-add-new-constraints-as-a-new-upper-bound-of-an-expression-in-jump-model/128850 "2025-05-12T20:39:52Z")

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I have a JuMP model called EP. I am trying to delete and re-add constraints called cMaxCap as an upper bound for an expression eTotalCap. This upper bound has values max\_cap\_mw. However, after deleting and re-adding, my…

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## [CUDA | nested loops kernel](https://discourse.julialang.org/t/cuda-nested-loops-kernel/128812)

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**Author:** [@Audrius-St](https://discourse.julialang.org/u/Audrius-St)\
**Replies:** 5\
**Last updated:** [May 12, 2025, 4:25pm UTC](https://discourse.julialang.org/t/cuda-nested-loops-kernel/128812 "2025-05-12T16:25:28Z")

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Hello, As part of learning to use CUDA in Julia, I wrote the following MWE to compare threaded CPU, CUDA array programming, and CUDA kernel programming performance for a simple element by element array multiplication. …

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## [Good ways to plot DataFrames content?](https://discourse.julialang.org/t/good-ways-to-plot-dataframes-content/128877)

<div class="topic-metadata">

**Author:** [@Torkel](https://discourse.julialang.org/u/Torkel)\
**Replies:** 12\
**Last updated:** [May 12, 2025, 9:26am UTC](https://discourse.julialang.org/t/good-ways-to-plot-dataframes-content/128877 "2025-05-12T09:26:58Z")

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I have never really gotten along with DataFrames very well (and to be fair, not used it that much). I figured I should ask if there are any straightforward recipes (or methods) for plotting the content of a DataFrame? (…

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## [ControlSystemsMTK: Easy Way to Initialize Output?](https://discourse.julialang.org/t/controlsystemsmtk-easy-way-to-initialize-output/128742)

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**Author:** [@TicTac](https://discourse.julialang.org/u/TicTac)\
**Replies:** 4\
**Last updated:** [May 12, 2025, 6:27am UTC](https://discourse.julialang.org/t/controlsystemsmtk-easy-way-to-initialize-output/128742 "2025-05-12T06:27:12Z")

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Is there a convenient way to the initialize the unknowns in a ODESystem created by ControlSystemsMTK based on a desired initial output? I needed a simple time delay model for something, and I figured using pade from Con…

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## [My Gurobi version is 12.0.2, but in julia it is still 12.0.1](https://discourse.julialang.org/t/my-gurobi-version-is-12-0-2-but-in-julia-it-is-still-12-0-1/128899)

<div class="topic-metadata">

**Author:** [@WalterMadelim](https://discourse.julialang.org/u/WalterMadelim)\
**Replies:** 2\
**Last updated:** [May 12, 2025, 12:00am UTC](https://discourse.julialang.org/t/my-gurobi-version-is-12-0-2-but-in-julia-it-is-still-12-0-1/128899 "2025-05-12T00:00:30Z")

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I update my gurobi optimizer today. And I’ve deleted all the previous version. But in julia it still shows the old version (cf. 🍅 lines). Is this normal? PS K:\\uc24\> gurobi Python 3.11.4 (tags/v3.11.4:d2340ef, Jun 7 20…

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## [A performant optimizing algorithm for a case with an expensive cost function and parallel execution](https://discourse.julialang.org/t/a-performant-optimizing-algorithm-for-a-case-with-an-expensive-cost-function-and-parallel-execution/128900)

<div class="topic-metadata">

**Author:** [@KajWiik](https://discourse.julialang.org/u/KajWiik)\
**Replies:** 4\
**Last updated:** [May 11, 2025, 4:43pm UTC](https://discourse.julialang.org/t/a-performant-optimizing-algorithm-for-a-case-with-an-expensive-cost-function-and-parallel-execution/128900 "2025-05-11T16:43:31Z")

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I have a very expensive multivariate cost function (FDTD simulation with openEMS) but I have resources to run many of them in parallel. What would be a good algorithm (and package) to implement this? A variant of differe…

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## [Propagate posterior samples from model calibration as the prior into an inverse problem](https://discourse.julialang.org/t/propagate-posterior-samples-from-model-calibration-as-the-prior-into-an-inverse-problem/128844)

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**Author:** [@Cory\_Simon](https://discourse.julialang.org/u/Cory_Simon)\
**Replies:** 5\
**Last updated:** [May 11, 2025, 6:52pm UTC](https://discourse.julialang.org/t/propagate-posterior-samples-from-model-calibration-as-the-prior-into-an-inverse-problem/128844 "2025-05-11T18:52:16Z")

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so I have a model y = f(x; \\theta). using (x, y) pairs, I get a posterior over theta. this constitutes “model calibration”. now I wanna use this posterior as the prior for an inverse problem, where I observe y and wann…

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## [How to save a trained policy in SDDP.jl?](https://discourse.julialang.org/t/how-to-save-a-trained-policy-in-sddp-jl/128894)

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**Author:** [@Engr\_Moiz\_Ahmad](https://discourse.julialang.org/u/Engr_Moiz_Ahmad)\
**Replies:** 2\
**Last updated:** [May 11, 2025, 5:48pm UTC](https://discourse.julialang.org/t/how-to-save-a-trained-policy-in-sddp-jl/128894 "2025-05-11T17:48:37Z")

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I am dealing with a multi-stage mixed-integer stochastic global supply chain optimization problem and want to solve it using the SDDiP algorithm using the SDDP.jl package in Julia. In this regard, I want to download the…

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## [SLOW\_PROGRESS or NUMERICAL\_ERROR: a simple but nontrivial SDP example, solved with LP relaxation](https://discourse.julialang.org/t/slow-progress-or-numerical-error-a-simple-but-nontrivial-sdp-example-solved-with-lp-relaxation/127399)

<div class="topic-metadata">

**Author:** [@WalterMadelim](https://discourse.julialang.org/u/WalterMadelim)\
**Replies:** 8\
**Last updated:** [May 11, 2025, 10:04am UTC](https://discourse.julialang.org/t/slow-progress-or-numerical-error-a-simple-but-nontrivial-sdp-example-solved-with-lp-relaxation/127399 "2025-05-11T10:04:38Z")

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I wonder why mosek cannot solve this simple problem to optimality (it reports SLOW\_PROGRESS). x-ref \[docs\] improve the docstring for DUAL\_INFEASIBLE by odow · Pull Request #2701 · jump-dev/MathOptInterface.jl · GitHub i…

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## [Best way to train and evaluate SDDP with constraints including product of control and states variables?](https://discourse.julialang.org/t/best-way-to-train-and-evaluate-sddp-with-constraints-including-product-of-control-and-states-variables/128890)

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**Author:** [@petr-a](https://discourse.julialang.org/u/petr-a)\
**Replies:** 1\
**Last updated:** [May 10, 2025, 11:27pm UTC](https://discourse.julialang.org/t/best-way-to-train-and-evaluate-sddp-with-constraints-including-product-of-control-and-states-variables/128890 "2025-05-10T23:27:30Z")

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Hello! I’m solving a problem which is similar to the Milk producer example with the SDDP algorithm. This question is also related to my first question about SDDP and out-of-sample solutions. Here is my asset managemen…

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## [Turing.jl programmatically set number of clusters in a mixture model](https://discourse.julialang.org/t/turing-jl-programmatically-set-number-of-clusters-in-a-mixture-model/126170)

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**Author:** [@apattyn](https://discourse.julialang.org/u/apattyn)\
**Replies:** 6\
**Last updated:** [May 10, 2025, 12:52pm UTC](https://discourse.julialang.org/t/turing-jl-programmatically-set-number-of-clusters-in-a-mixture-model/126170 "2025-05-10T12:52:05Z")

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I am trying to model some data using a mixture model with Turing.jl, but I want to programmatically set the number of Gaussian in the mixture without having to edit the model. For example if I want ten Gaussians I don’t …

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## [SQLite and DBInterface prepared statement error](https://discourse.julialang.org/t/sqlite-and-dbinterface-prepared-statement-error/128882)

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**Author:** [@slwu89](https://discourse.julialang.org/u/slwu89)\
**Replies:** 5\
**Last updated:** [May 9, 2025, 10:32pm UTC](https://discourse.julialang.org/t/sqlite-and-dbinterface-prepared-statement-error/128882 "2025-05-09T22:32:14Z")

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Hi all. Does SQLite.jl support DBInterface.jl prepared statements? My MWE is below. When running the DBInterface.prepare line I get an error (pasted below the MWE). On \[0aa819cd\] SQLite v1.6.1. When using DuckDB.jl as th…

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## [Help to use AD with Optimization.jl](https://discourse.julialang.org/t/help-to-use-ad-with-optimization-jl/128866)

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**Author:** [@Maucejo](https://discourse.julialang.org/u/Maucejo)\
**Replies:** 5\
**Last updated:** [May 9, 2025, 2:40pm UTC](https://discourse.julialang.org/t/help-to-use-ad-with-optimization-jl/128866 "2025-05-09T14:40:52Z")

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Hi all, I need your advice to use automatic differentiation with Optimization.jl. The problem - I try to find the optimal variance of a process noise covariance matrix of a standard Kalman filter. Currently, I use grad…

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## [Are forward-mode derivatives calculated in parallel?](https://discourse.julialang.org/t/are-forward-mode-derivatives-calculated-in-parallel/128870)

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**Author:** [@Bizzi](https://discourse.julialang.org/u/Bizzi)\
**Replies:** 1\
**Last updated:** [May 9, 2025, 10:57am UTC](https://discourse.julialang.org/t/are-forward-mode-derivatives-calculated-in-parallel/128870 "2025-05-09T10:57:47Z")

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When I calculate the output of a function and a directional derivative using forward-mode autodiff (ForwardDiff, TaylorDiff etc), is the calculation of the derivatives carried out in parallel? By parallel I mean: assumi…

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## [Warning: Package cuDNN not found in current path](https://discourse.julialang.org/t/warning-package-cudnn-not-found-in-current-path/104242)

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**Author:** [@wsshin](https://discourse.julialang.org/u/wsshin)\
**Replies:** 5\
**Last updated:** [May 8, 2025, 10:22pm UTC](https://discourse.julialang.org/t/warning-package-cudnn-not-found-in-current-path/104242 "2025-05-08T22:22:09Z")

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I get this warning while using Flux on a CUDA GPU: ┌ Warning: Package cuDNN not found in current path. │ - Run \`import Pkg; Pkg.add("cuDNN")\` to install the cuDNN package, then restart julia. │ - If cuDNN is not install…

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## [How to license CPLEX inside Google Colab’s Julia environment](https://discourse.julialang.org/t/how-to-license-cplex-inside-google-colab-s-julia-environment/128682)

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**Author:** [@Engr\_Moiz\_Ahmad](https://discourse.julialang.org/u/Engr_Moiz_Ahmad)\
**Replies:** 9\
**Last updated:** [May 8, 2025, 7:11pm UTC](https://discourse.julialang.org/t/how-to-license-cplex-inside-google-colab-s-julia-environment/128682 "2025-05-08T19:11:40Z")

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I am dealing with a multi-stage mixed-integer stochastic global supply chain optimization problem and want to solve the stage-wise problem instances using the CPLEX solver within SDDiP algorithm using the SDDP.jl package…

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## [Simplifying Iwasawa decomposition with Symbolics.jl](https://discourse.julialang.org/t/simplifying-iwasawa-decomposition-with-symbolics-jl/128842)

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**Author:** [@potatoh8](https://discourse.julialang.org/u/potatoh8)\
**Replies:** 0\
**Last updated:** [May 8, 2025, 3:42pm UTC](https://discourse.julialang.org/t/simplifying-iwasawa-decomposition-with-symbolics-jl/128842 "2025-05-08T15:42:31Z")

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I’m trying to verify the following matrix identity using Symbolics.jl: Here’s my attempt: using Symbolics function SL2CIwasawaDecomp(X) # given matrix X in SL2C, return tuple (z, r, α, β) such that # X = n(z…

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## [Counter-intuitive difference in matrix-vector multiplication when the matrix is transposed](https://discourse.julialang.org/t/counter-intuitive-difference-in-matrix-vector-multiplication-when-the-matrix-is-transposed/127479)

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**Author:** [@mrkn](https://discourse.julialang.org/u/mrkn)\
**Replies:** 4\
**Last updated:** [May 8, 2025, 6:41am UTC](https://discourse.julialang.org/t/counter-intuitive-difference-in-matrix-vector-multiplication-when-the-matrix-is-transposed/127479 "2025-05-08T06:41:11Z")

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I found that matrix-vector multiplication in Julia uses a different algorithm when the matrix is wrapped by Transpose or Adjoint, compared to when it is a regular Matrix. As a result, the multiplication can sometimes pro…

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## [ControlSystems.jl: Custom labels in a plot of step response of a MIMO system](https://discourse.julialang.org/t/controlsystems-jl-custom-labels-in-a-plot-of-step-response-of-a-mimo-system/128821)

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**Author:** [@zdenek\_hurak](https://discourse.julialang.org/u/zdenek_hurak)\
**Replies:** 2\
**Last updated:** [May 8, 2025, 4:56am UTC](https://discourse.julialang.org/t/controlsystems-jl-custom-labels-in-a-plot-of-step-response-of-a-mimo-system/128821 "2025-05-08T04:56:28Z")

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I am struggling with setting my own labels correctly in a plot of a step response of a MIMO system. Consider a generic MIMO LTI system with 2 inputs and 2 outputs, say: using ControlSystems using Plots A = \[-10 2; 3 -4…

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## [Wave Equation Numerically Solved?](https://discourse.julialang.org/t/wave-equation-numerically-solved/128820)

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**Author:** [@wbradycall](https://discourse.julialang.org/u/wbradycall)\
**Replies:** 2\
**Last updated:** [May 8, 2025, 12:12am UTC](https://discourse.julialang.org/t/wave-equation-numerically-solved/128820 "2025-05-08T00:12:34Z")

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Any good example of the wave equation solved numerically? Brady Call

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## [Slow array access during labeling algorithm](https://discourse.julialang.org/t/slow-array-access-during-labeling-algorithm/128366)

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**Author:** [@Walter](https://discourse.julialang.org/u/Walter)\
**Replies:** 9\
**Last updated:** [May 7, 2025, 8:03pm UTC](https://discourse.julialang.org/t/slow-array-access-during-labeling-algorithm/128366 "2025-05-07T20:03:12Z")

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Hi all, I switched from Python to Julia and are currently implementing a column generation algorithm for a vehicle routing problem. To generate a column (route) with negative reduced cost, I use a labeling algorithm. T…

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## [Logging events when running a CTMC](https://discourse.julialang.org/t/logging-events-when-running-a-ctmc/128778)

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**Author:** [@julien-arino](https://discourse.julialang.org/u/julien-arino)\
**Replies:** 3\
**Last updated:** [May 7, 2025, 6:24pm UTC](https://discourse.julialang.org/t/logging-events-when-running-a-ctmc/128778 "2025-05-07T18:24:24Z")

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At the bottom of this message is a sample piece of code (which should run) that illustrates the reason for my question (slash feature request in disguise): when using DifferentialEquations.jl to run a continuous time Mar…

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