# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1692

[Latest](https://discourse.julialang.org/latest.md) · [Categories](https://discourse.julialang.org/categories.md) · [Tags](https://discourse.julialang.org/tags.md)

**Page:** 1693

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## [\[HOWTO\] Call a process and getting it's info?](https://discourse.julialang.org/t/howto-call-a-process-and-getting-its-info/42854)

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**Author:** [@phykos](https://discourse.julialang.org/u/phykos)\
**Replies:** 4\
**Last updated:** [July 11, 2020, 1:25pm UTC](https://discourse.julialang.org/t/howto-call-a-process-and-getting-its-info/42854 "2020-07-11T13:25:21Z")

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I want to call, for example the process ls -a, and from that, I want it’s total time, user time, system time, cpu time, RAM used etc., like the time commands available in most shells, such as bash, zsh and so on. How ca…

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## [Versioning of documentation fails](https://discourse.julialang.org/t/versioning-of-documentation-fails/42795)

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**Author:** [@lgo](https://discourse.julialang.org/u/lgo)\
**Replies:** 4\
**Last updated:** [July 11, 2020, 12:27pm UTC](https://discourse.julialang.org/t/versioning-of-documentation-fails/42795 "2020-07-11T12:27:04Z")

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I’m trying to achieve versioning for my documentation created with documenter. I’ve set the devbranch = "dev" in the deploydocs function, but use the defaults apart from that. Yet still, in the documenation the dropdown …

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## [Extract neighbors from first shell of Voronoi tesselation](https://discourse.julialang.org/t/extract-neighbors-from-first-shell-of-voronoi-tesselation/42844)

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**Author:** [@cheins](https://discourse.julialang.org/u/cheins)\
**Replies:** 3\
**Last updated:** [July 11, 2020, 10:03am UTC](https://discourse.julialang.org/t/extract-neighbors-from-first-shell-of-voronoi-tesselation/42844 "2020-07-11T10:03:59Z")

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I’m assuming the best answer to this question requires using VoronoiDelaunay.jl, but I’m also open to other packages/approaches. If I have a set of points in 2D (or 3D? Though not I’m not sure this is possible with the …

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## [\[ANN\] CompactBases.jl](https://discourse.julialang.org/t/ann-compactbases-jl/42888)

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**Author:** [@jagot](https://discourse.julialang.org/u/jagot)\
**Replies:** 0\
**Last updated:** [July 11, 2020, 8:35am UTC](https://discourse.julialang.org/t/ann-compactbases-jl/42888 "2020-07-11T08:35:20Z")

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Introduction I’m happy to announce the first release of CompactBases.jl, a library for easily approximating functions and matrix representations of linear operators in various bases where the basis functions have compact…

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## [test/Project.toml](https://discourse.julialang.org/t/test-project-toml/42868)

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**Author:** [@alan](https://discourse.julialang.org/u/alan)\
**Replies:** 11\
**Last updated:** [July 11, 2020, 3:56am UTC](https://discourse.julialang.org/t/test-project-toml/42868 "2020-07-11T03:56:36Z")

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Using Julia 1.4.1, I added StaticArrays as a dependency to my project using add StaticArrays within Pkg mode. This generated an entry in Project.toml. But when I run test within Pkg mode, I get a load error saying that S…

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## [Update fails when remote does not "negotiate mechanisms"](https://discourse.julialang.org/t/update-fails-when-remote-does-not-negotiate-mechanisms/42883)

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**Author:** [@SocksNSandals](https://discourse.julialang.org/u/SocksNSandals)\
**Replies:** 0\
**Last updated:** [July 11, 2020, 2:43am UTC](https://discourse.julialang.org/t/update-fails-when-remote-does-not-negotiate-mechanisms/42883 "2020-07-11T02:43:00Z")

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I attempted to do a \]update on a private julia repo and got the following error: (mypackage) pkg\> update Updating registry at \`~/.julia/registries/General\` Updating git-repo \`https://github.com/JuliaRegistries/Gen…

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## [Gurobi "Objective Q not PSD " for Convex quadratic problem](https://discourse.julialang.org/t/gurobi-objective-q-not-psd-for-convex-quadratic-problem/42689)

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**Author:** [@Ken\_Lin](https://discourse.julialang.org/u/Ken_Lin)\
**Replies:** 5\
**Last updated:** [July 11, 2020, 2:42am UTC](https://discourse.julialang.org/t/gurobi-objective-q-not-psd-for-convex-quadratic-problem/42689 "2020-07-11T02:42:10Z")

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I got this error when using Gurobi 9.0.1 in Julia 1.3.1: Gurobi.GurobiError(10020, "Objective Q not PSD (diagonal adjustment of 5.8e-01 would be required)") However, I’m sure that my problem is convex, as you can see fr…

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## [Revisited : passing and returning arrays with unspecified type](https://discourse.julialang.org/t/revisited-passing-and-returning-arrays-with-unspecified-type/42859)

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**Author:** [@iamsuddhasattwa](https://discourse.julialang.org/u/iamsuddhasattwa)\
**Replies:** 4\
**Last updated:** [July 11, 2020, 12:07am UTC](https://discourse.julialang.org/t/revisited-passing-and-returning-arrays-with-unspecified-type/42859 "2020-07-11T00:07:13Z")

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I had previously asked how to pass arrays of unspecified type as input to a function, to which I had got a nice solution using where T. Hoewever, I am having a problem when trying to specify the output type as an Array o…

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## [Loop for minimizing functions with a varying number of arguments](https://discourse.julialang.org/t/loop-for-minimizing-functions-with-a-varying-number-of-arguments/42816)

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**Author:** [@sergevic](https://discourse.julialang.org/u/sergevic)\
**Replies:** 12\
**Last updated:** [July 11, 2020, 12:03am UTC](https://discourse.julialang.org/t/loop-for-minimizing-functions-with-a-varying-number-of-arguments/42816 "2020-07-11T00:03:56Z")

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I have to build a loop where each iteration consists in building a function to minimize. At each iteration, the number of arguments is variable. To start, I have two matrices: X=rand(150,100) Y=rand(150,1) At each ite…

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## [Finding documentation and function descriptions](https://discourse.julialang.org/t/finding-documentation-and-function-descriptions/42446)

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**Author:** [@iamsuddhasattwa](https://discourse.julialang.org/u/iamsuddhasattwa)\
**Replies:** 5\
**Last updated:** [July 11, 2020, 12:03am UTC](https://discourse.julialang.org/t/finding-documentation-and-function-descriptions/42446 "2020-07-11T00:03:32Z")

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A problem I often face while trying to learn about new packages is finding the documentation, detailed list and description of functions etc. Often we search how to perform a certain task in Julia and our search leads us…

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## [Add instantiation of object to vector](https://discourse.julialang.org/t/add-instantiation-of-object-to-vector/42867)

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**Author:** [@zazizoma](https://discourse.julialang.org/u/zazizoma)\
**Replies:** 2\
**Last updated:** [July 10, 2020, 11:09pm UTC](https://discourse.julialang.org/t/add-instantiation-of-object-to-vector/42867 "2020-07-10T23:09:22Z")

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Hello, I have defined an object via a mutable struct and I would like to instantiate n of them into a vector. Ultimately, I’d like to refer two them as vector\[i\]. Here’s MWE: mutable struct Foo x :: Float64 y :: Flo…

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## [Implementing a Kalman filter for a differential equation system](https://discourse.julialang.org/t/implementing-a-kalman-filter-for-a-differential-equation-system/42879)

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**Author:** [@affans](https://discourse.julialang.org/u/affans)\
**Replies:** 0\
**Last updated:** [July 10, 2020, 11:02pm UTC](https://discourse.julialang.org/t/implementing-a-kalman-filter-for-a-differential-equation-system/42879 "2020-07-10T23:02:39Z")

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I am trying to implement a very simple Kalman Filter for learning purposes. I am following the example here (example 2, page 5). I will summarize it here with a MWE so no need to really go to the PDF. Consider the follo…

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## [Updating a data with new data, removing redundancies](https://discourse.julialang.org/t/updating-a-data-with-new-data-removing-redundancies/42858)

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**Author:** [@Nash](https://discourse.julialang.org/u/Nash)\
**Replies:** 10\
**Last updated:** [July 10, 2020, 8:47pm UTC](https://discourse.julialang.org/t/updating-a-data-with-new-data-removing-redundancies/42858 "2020-07-10T20:47:39Z")

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Suppose I have four corresponding arrays relating to stock market data. Also, suppose I assemble them into a matrix: dataold = \[mktId stockId totalVolume price timeStamp\] I proceed to gather more data of the stated kin…

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## [Writing a new subtype of AbstractArray](https://discourse.julialang.org/t/writing-a-new-subtype-of-abstractarray/42746)

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**Author:** [@alan](https://discourse.julialang.org/u/alan)\
**Replies:** 4\
**Last updated:** [July 10, 2020, 8:36pm UTC](https://discourse.julialang.org/t/writing-a-new-subtype-of-abstractarray/42746 "2020-07-10T20:36:48Z")

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I’ve just defined a new type, which represents a lower-triangular matrix and is a subtype of AbstractArray. I extended all the methods required by that interface. When I create an object of this type in the REPL, Julia t…

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## [How to Get Outputs from ccall](https://discourse.julialang.org/t/how-to-get-outputs-from-ccall/42864)

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**Author:** [@duncanam](https://discourse.julialang.org/u/duncanam)\
**Replies:** 2\
**Last updated:** [July 10, 2020, 8:10pm UTC](https://discourse.julialang.org/t/how-to-get-outputs-from-ccall/42864 "2020-07-10T20:10:45Z")

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Hi, I’m trying to port some MATLAB code over to Julia that relies on some of MATLAB’s calllib() functions. However, I am confused how I am supposed to get multiple outputs out of Julia’s ccall() function as we are only a…

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## [Loss function for sequence modeling w/ RNN](https://discourse.julialang.org/t/loss-function-for-sequence-modeling-w-rnn/42452)

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**Author:** [@austinbean](https://discourse.julialang.org/u/austinbean)\
**Replies:** 1\
**Last updated:** [July 10, 2020, 7:42pm UTC](https://discourse.julialang.org/t/loss-function-for-sequence-modeling-w-rnn/42452 "2020-07-10T19:42:15Z")

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I’d like advice on the best way to model the loss function in Flux for an RNN where I’m modeling a sequence of words in labeled sentences. (This is for a regression task, but a sentiment analysis task would look similar…

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## [Correct way to wait for a Timer callback to execute](https://discourse.julialang.org/t/correct-way-to-wait-for-a-timer-callback-to-execute/42320)

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**Author:** [@DrChainsaw](https://discourse.julialang.org/u/DrChainsaw)\
**Replies:** 2\
**Last updated:** [July 10, 2020, 7:36pm UTC](https://discourse.julialang.org/t/correct-way-to-wait-for-a-timer-callback-to-execute/42320 "2020-07-10T19:36:20Z")

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Use case in case it matters is to have non-flaky unit tests without having to over-abstract things (which is why I’d prefer to not have some boolean iscallbackdone inside the callback). function testtimer() ss = "" …

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## [Multiplication performance](https://discourse.julialang.org/t/multiplication-performance/42862)

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**Author:** [@Joao\_Barata](https://discourse.julialang.org/u/Joao_Barata)\
**Replies:** 8\
**Last updated:** [July 10, 2020, 6:42pm UTC](https://discourse.julialang.org/t/multiplication-performance/42862 "2020-07-10T18:42:05Z")

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Hey guys, Here is a very simple code I’m using: function tax\_labor(τ0\_y::Real,τ1\_y::Real,ρ\_τ::Real,barρ::Real,earn::Real,rent::Real) τ0\_y\*(earn - min(ρ\_τ\*rent,barρ))^(1.0-τ1\_y) end If I do @btime, I get 9.6 ns. No…

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## [Julia project ideas](https://discourse.julialang.org/t/julia-project-ideas/42815)

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**Author:** [@jguo](https://discourse.julialang.org/u/jguo)\
**Replies:** 2\
**Last updated:** [July 10, 2020, 6:20pm UTC](https://discourse.julialang.org/t/julia-project-ideas/42815 "2020-07-10T18:20:03Z")

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Dear Julia Community, I am new to Julia but I believe the best way to learn a new language is to use it to solve problems as much as possible. I use resources like ThinkJulia and lectures on Quantitative Economics with …

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## [Uber-juno doesn't reinstall dependent packages](https://discourse.julialang.org/t/uber-juno-doesnt-reinstall-dependent-packages/42860)

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**Author:** [@CraigCottingham](https://discourse.julialang.org/u/CraigCottingham)\
**Replies:** 0\
**Last updated:** [July 10, 2020, 5:53pm UTC](https://discourse.julialang.org/t/uber-juno-doesnt-reinstall-dependent-packages/42860 "2020-07-10T17:53:20Z")

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I installed uber-juno 0.3.0 in Atom 1.48.0 and let it set panes to be opened automatically (however that option was named). However, I didn’t understand that it opens the Juno panes for all file types (not just Julia fil…

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## [iPython in Julia](https://discourse.julialang.org/t/ipython-in-julia/42841)

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**Author:** [@sbacelar](https://discourse.julialang.org/u/sbacelar)\
**Replies:** 8\
**Last updated:** [July 10, 2020, 5:50pm UTC](https://discourse.julialang.org/t/ipython-in-julia/42841 "2020-07-10T17:50:30Z")

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Is there anything similar to iPython in Julia (not iJulia I suppose).

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## [Unitful, dispatch on u"1/s" and u"rad/s"](https://discourse.julialang.org/t/unitful-dispatch-on-u-1-s-and-u-rad-s/42851)

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**Author:** [@Olivier\_Merchiers](https://discourse.julialang.org/u/Olivier_Merchiers)\
**Replies:** 2\
**Last updated:** [July 10, 2020, 5:02pm UTC](https://discourse.julialang.org/t/unitful-dispatch-on-u-1-s-and-u-rad-s/42851 "2020-07-10T17:02:33Z")

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Hello everyone, This is a follow up question from this topic. Now instead of just the unit I would like to have different quantities. Let me explain. I want to dispatch on units of 1/s and rad/s. Now I do the followi…

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## [Matrix multiplication and element-wise operations without extra pre-allocation of memory](https://discourse.julialang.org/t/matrix-multiplication-and-element-wise-operations-without-extra-pre-allocation-of-memory/42855)

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**Author:** [@aaraujo71](https://discourse.julialang.org/u/aaraujo71)\
**Replies:** 5\
**Last updated:** [July 10, 2020, 5:45pm UTC](https://discourse.julialang.org/t/matrix-multiplication-and-element-wise-operations-without-extra-pre-allocation-of-memory/42855 "2020-07-10T17:45:35Z")

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Hi, I would like to perform the following element operations to a matrix W (m rows and n columns): W(i, j) := a\*W(i, j) - b\*d(j)y(i), where a and b are scalars, d(j) are the elements of a vector d with n elements, and…

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## [Parallel program with external software works from REPL but not from command line](https://discourse.julialang.org/t/parallel-program-with-external-software-works-from-repl-but-not-from-command-line/42757)

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**Author:** [@PlasmaJoe](https://discourse.julialang.org/u/PlasmaJoe)\
**Replies:** 7\
**Last updated:** [July 10, 2020, 5:13pm UTC](https://discourse.julialang.org/t/parallel-program-with-external-software-works-from-repl-but-not-from-command-line/42757 "2020-07-10T17:13:28Z")

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I’m trying to set up Julia to interact with an external program. I need to run the external program a lot and I have access to a cluster so since the external program only uses one core I think it makes sense to distribu…

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## [Is there a way to trace/debug all message passing in languageserver.jl? (trying to get lsp to work in emacs)](https://discourse.julialang.org/t/is-there-a-way-to-trace-debug-all-message-passing-in-languageserver-jl-trying-to-get-lsp-to-work-in-emacs/42788)

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**Author:** [@spence](https://discourse.julialang.org/u/spence)\
**Replies:** 5\
**Last updated:** [July 10, 2020, 4:59pm UTC](https://discourse.julialang.org/t/is-there-a-way-to-trace-debug-all-message-passing-in-languageserver-jl-trying-to-get-lsp-to-work-in-emacs/42788 "2020-07-10T16:59:21Z")

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I’m trying to get lsp-julia to work in Emacs with its lsp-mode. I’ve hacked around on lsp-julia and it appears I’ve been able to get it to interact with lsp-mode and start the language server properly with 1.4.2 (it had…

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## [Plots.jl crash](https://discourse.julialang.org/t/plots-jl-crash/42852)

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**Author:** [@Honza9723](https://discourse.julialang.org/u/Honza9723)\
**Replies:** 2\
**Last updated:** [July 10, 2020, 4:52pm UTC](https://discourse.julialang.org/t/plots-jl-crash/42852 "2020-07-10T16:52:57Z")

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Hi, after updating package Plots.jl, the command “using Plots” gave me the following error. Re-building package doesn’t help, however, other packages work without any problem. Could somebody please give me some advice h…

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## [Model constraint error](https://discourse.julialang.org/t/model-constraint-error/42850)

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**Author:** [@RaquelSantos](https://discourse.julialang.org/u/RaquelSantos)\
**Replies:** 2\
**Last updated:** [July 10, 2020, 4:45pm UTC](https://discourse.julialang.org/t/model-constraint-error/42850 "2020-07-10T16:45:46Z")

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How to solve this error? BoundsError: attempt to access 2×2 Array{Int64,2} at index \[1, 3\] using JuMP, Cbc Model1 = Model(with\_optimizer(Cbc.Optimizer)) t = 4 w = 2 T = 1:t W = 1:w WH = \[2489 1447; 11073 5414\] @vari…

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## [Linear algebra performance issue](https://discourse.julialang.org/t/linear-algebra-performance-issue/42353)

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**Author:** [@vinhphunguyen](https://discourse.julialang.org/u/vinhphunguyen)\
**Replies:** 20\
**Last updated:** [July 10, 2020, 3:39pm UTC](https://discourse.julialang.org/t/linear-algebra-performance-issue/42353 "2020-07-10T15:39:38Z")

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Hello all, I need to compute a 3x3 matrix many many times, it is given by P = J x sigma x inv(F)‘, where J is a scalar, sigma and F are 3x3 matrices; A’ =\> transpose of A. What is the best way to compute this P as f…

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## [ERROR: LoadError: Need an adjoint for constructor EnsembleSolution](https://discourse.julialang.org/t/error-loaderror-need-an-adjoint-for-constructor-ensemblesolution/42611)

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**Author:** [@yanz4](https://discourse.julialang.org/u/yanz4)\
**Replies:** 9\
**Last updated:** [July 10, 2020, 3:11pm UTC](https://discourse.julialang.org/t/error-loaderror-need-an-adjoint-for-constructor-ensemblesolution/42611 "2020-07-10T15:11:49Z")

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I wish to use Flux.training to optimize a parameter in parallel ensemble simulation, but it shows adjoint error as below: ERROR: LoadError: Need an adjoint for constructor EnsembleSolution{Float64,2,Array{ODESolution{F…

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## [Solve the System of Equations (J' J + μI) x = J'v](https://discourse.julialang.org/t/solve-the-system-of-equations-j-j-i-x-jv/42766)

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**Author:** [@Norman](https://discourse.julialang.org/u/Norman)\
**Replies:** 6\
**Last updated:** [July 10, 2020, 2:36pm UTC](https://discourse.julialang.org/t/solve-the-system-of-equations-j-j-i-x-jv/42766 "2020-07-10T14:36:44Z")

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I have a square sparse matrix J of size n \* n where n can be around 1 million. μ is a scalar. I is the identity matrix. v is a vector. The system to be solved is (J'J + μI) x = J'v What I have now is the following: H…

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