# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=464

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**Page:** 465

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## [On solving sets of linear equations in Fortran vs Julia](https://discourse.julialang.org/t/on-solving-sets-of-linear-equations-in-fortran-vs-julia/33729)

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**Author:** [@razvangheorghe](https://discourse.julialang.org/u/razvangheorghe)\
**Replies:** 14\
**Last updated:** [February 7, 2020, 12:23pm UTC](https://discourse.julialang.org/t/on-solving-sets-of-linear-equations-in-fortran-vs-julia/33729 "2020-02-07T12:23:27Z")

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Hi, I’d like to translate a Fortran 90 program to Julia and then continue with my development in Julia. The bottleneck right now seem to be the solving of around 100 systems of linear equations where the matrix (~400x400…

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## [Gen install](https://discourse.julialang.org/t/gen-install/26459)

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**Author:** [@kadir.nar](https://discourse.julialang.org/u/kadir.nar)\
**Replies:** 10\
**Last updated:** [February 7, 2020, 4:21am UTC](https://discourse.julialang.org/t/gen-install/26459 "2020-02-07T04:21:16Z")

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“pkg\> add GitHub - probcomp/Gen.jl: A general-purpose probabilistic programming system with programmable inference” “ERROR: syntax: extra token “https” after end of expression.” Can you help me? Thanks.

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## [Improving cache behavior with ldg()](https://discourse.julialang.org/t/improving-cache-behavior-with-ldg/33628)

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**Author:** [@Michael\_Benton](https://discourse.julialang.org/u/Michael_Benton)\
**Replies:** 6\
**Last updated:** [February 6, 2020, 11:56pm UTC](https://discourse.julialang.org/t/improving-cache-behavior-with-ldg/33628 "2020-02-06T23:56:02Z")

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What exactly is meant by https://juliagpu.github.io/CUDAnative.jl/stable/lib/device/array.html that ldg “loads the value through the read-only texture cache for improved cache behavior” ? The following is a memory band…

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## [JuMP: Hermitian matrix variable and complex numbers in model](https://discourse.julialang.org/t/jump-hermitian-matrix-variable-and-complex-numbers-in-model/34230)

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**Author:** [@martincornejo](https://discourse.julialang.org/u/martincornejo)\
**Replies:** 2\
**Last updated:** [February 6, 2020, 4:01pm UTC](https://discourse.julialang.org/t/jump-hermitian-matrix-variable-and-complex-numbers-in-model/34230 "2020-02-06T16:01:56Z")

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I’ve been playing around with JuMP and trying to develop on my own OPF models and I’ve had some difficulty since JuMP doesn’t support complex numbers. Specially the SDP relaxation of the OPF has been tricky since I don’t…

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## [Problem with variable scope when translating from Matlab to Julia](https://discourse.julialang.org/t/problem-with-variable-scope-when-translating-from-matlab-to-julia/34200)

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**Author:** [@Ujku\_KU](https://discourse.julialang.org/u/Ujku_KU)\
**Replies:** 8\
**Last updated:** [February 6, 2020, 2:43am UTC](https://discourse.julialang.org/t/problem-with-variable-scope-when-translating-from-matlab-to-julia/34200 "2020-02-06T02:43:16Z")

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Hi guys my problem is as follows: buff = g0 for i\_exh in 1:k f\_exh = obj\_rbfS3(x + y\_exh\[i\_exh\] \* v, X, ...) if f\_exh\[1,1\] \> buff\[1,1\] if i\_exh \> 1 gp\_exh = rbf\_dirS3(x + y\_exh\[i\_exh - 1\] \* v…

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## [Error installing Pajarito solver](https://discourse.julialang.org/t/error-installing-pajarito-solver/34223)

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**Author:** [@biswajit216](https://discourse.julialang.org/u/biswajit216)\
**Replies:** 1\
**Last updated:** [February 5, 2020, 10:25pm UTC](https://discourse.julialang.org/t/error-installing-pajarito-solver/34223 "2020-02-05T22:25:36Z")

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Hi, I was trying to add Pajarito package to my Julia but I was getting this error. My JuMP version is 0.20.1 pkg\> add Pajarito Resolving package versions… ERROR: Unsatisfiable requirements detected for package JuMP \[4…

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## [The error of using GLPKMathProgInterface pkg](https://discourse.julialang.org/t/the-error-of-using-glpkmathproginterface-pkg/34142)

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**Author:** [@mahsap58](https://discourse.julialang.org/u/mahsap58)\
**Replies:** 3\
**Last updated:** [February 5, 2020, 10:21pm UTC](https://discourse.julialang.org/t/the-error-of-using-glpkmathproginterface-pkg/34142 "2020-02-05T22:21:36Z")

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i have faced to this error in using GLPKMathProgInterface pkg please help me to fix that. Failed to precompile GLPK \[60bf3e95-4087-53dc-ae20-288a0d20c6a6\]

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## [Add Package on every processor?](https://discourse.julialang.org/t/add-package-on-every-processor/33853)

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**Author:** [@squirrel](https://discourse.julialang.org/u/squirrel)\
**Replies:** 6\
**Last updated:** [February 5, 2020, 7:30pm UTC](https://discourse.julialang.org/t/add-package-on-every-processor/33853 "2020-02-05T19:30:25Z")

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I’m trying to use DistributedArrays (per the example), but it seems like the package needs to be added to every processor. Is this right? When I first start Julia, and run using Distributed addprocs() @everywhere using…

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## [AlexNet import to Julia](https://discourse.julialang.org/t/alexnet-import-to-julia/34209)

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**Author:** [@samantp](https://discourse.julialang.org/u/samantp)\
**Replies:** 1\
**Last updated:** [February 5, 2020, 4:13pm UTC](https://discourse.julialang.org/t/alexnet-import-to-julia/34209 "2020-02-05T16:13:46Z")

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I am trying to download and modify AlexNet, the well known pre-trained neural network into Julia. Are there any packages that have already done this or have well known pre-trained NN’s that are open to modification? I a…

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## [How to check if a solver supports SOS2 constraints](https://discourse.julialang.org/t/how-to-check-if-a-solver-supports-sos2-constraints/34186)

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**Author:** [@ohmsweetohm1](https://discourse.julialang.org/u/ohmsweetohm1)\
**Replies:** 3\
**Last updated:** [February 5, 2020, 2:22pm UTC](https://discourse.julialang.org/t/how-to-check-if-a-solver-supports-sos2-constraints/34186 "2020-02-05T14:22:59Z")

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I have a piece of code that adds SOS2 constraints to a model. If the solver supports it, I would like to use its interface, if not I would assemble the constraints myself. Is there a way to check if an optimizer suppor…

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## [How to set the zoomspeed for Camera3D in Makie.jl](https://discourse.julialang.org/t/how-to-set-the-zoomspeed-for-camera3d-in-makie-jl/34205)

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**Author:** [@JesperMartinsson](https://discourse.julialang.org/u/JesperMartinsson)\
**Replies:** 0\
**Last updated:** [February 5, 2020, 11:58am UTC](https://discourse.julialang.org/t/how-to-set-the-zoomspeed-for-camera3d-in-makie-jl/34205 "2020-02-05T11:58:11Z")

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Is there a way to adjust the zoom speed (when scrolling the mouse) in Makie.jl and using a 3D camera? I can set the rotationspeed in 3D and zoomspeed in 2D but not zoomspeed in 3D. Thanks for a great package by the way!

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## [Debugging in CUDAnative](https://discourse.julialang.org/t/debugging-in-cudanative/34193)

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**Author:** [@Michael\_Benton](https://discourse.julialang.org/u/Michael_Benton)\
**Replies:** 1\
**Last updated:** [February 5, 2020, 7:01am UTC](https://discourse.julialang.org/t/debugging-in-cudanative/34193 "2020-02-05T07:01:51Z")

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struggling to find the source of problems in some kernels I write due to I don’t know of a julia CUDA debugger, I’ve found some for C. I get: CUDA error: unspecified launch failure (code 719, ERROR\_LAUNCH\_FAILED) and …

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## [CuArray can't find libcuda](https://discourse.julialang.org/t/cuarray-cant-find-libcuda/34175)

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**Author:** [@cuchxq](https://discourse.julialang.org/u/cuchxq)\
**Replies:** 10\
**Last updated:** [February 5, 2020, 6:59am UTC](https://discourse.julialang.org/t/cuarray-cant-find-libcuda/34175 "2020-02-05T06:59:33Z")

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I installed cuda10.2 on a ubuntu 18.10, and was able to build and run the some examples from the Cuda example folder, such as devicequery. But when I use Julia1.0.5LTS, and CuArray can’t find libcuda. and using JULIA\_D…

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## [\[ANN\] Flux v0.10](https://discourse.julialang.org/t/ann-flux-v0-10/31660)

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**Author:** [@dhairyagandhi96](https://discourse.julialang.org/u/dhairyagandhi96)\
**Replies:** 36\
**Last updated:** [February 4, 2020, 7:57pm UTC](https://discourse.julialang.org/t/ann-flux-v0-10/31660 "2020-02-04T19:57:14Z")

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We are delighted to announce the release of Flux v0.10. This is a huge release including the work of many contributors; the major development is that Flux now uses Zygote as its default backend for gradients, removing m…

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## [Warning for adding constraints: zero or small (\< 1e-13) coefficients, ignored](https://discourse.julialang.org/t/warning-for-adding-constraints-zero-or-small-1e-13-coefficients-ignored/34137)

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**Author:** [@Arega\_Getaneh](https://discourse.julialang.org/u/Arega_Getaneh)\
**Replies:** 8\
**Last updated:** [February 4, 2020, 5:32pm UTC](https://discourse.julialang.org/t/warning-for-adding-constraints-zero-or-small-1e-13-coefficients-ignored/34137 "2020-02-04T17:32:31Z")

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I asked this question and it seems no one wants to help me: I am just using Gurobi 9.0 which solves non convex problems as well. I get this error: Warning for adding constraints: zero or small (\< 1e-13) coefficients, ig…

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## [Zygote: treating a model output as a constant](https://discourse.julialang.org/t/zygote-treating-a-model-output-as-a-constant/34172)

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**Author:** [@HenriDeh](https://discourse.julialang.org/u/HenriDeh)\
**Replies:** 2\
**Last updated:** [February 4, 2020, 5:18pm UTC](https://discourse.julialang.org/t/zygote-treating-a-model-output-as-a-constant/34172 "2020-02-04T17:18:46Z")

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Say I have a model m = Dense(1,1), a function f(x) = x, and a loss(a,b,c) = m(a) - b - f(c). I don’t want zygote to differentiate on f(c) when calling gradient(() -\> loss(a,b,c), m) . How do I tell it that ? It is a pro…

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## [Different results for same model with DifferentialEquations.jl](https://discourse.julialang.org/t/different-results-for-same-model-with-differentialequations-jl/34155)

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**Author:** [@moesphere](https://discourse.julialang.org/u/moesphere)\
**Replies:** 4\
**Last updated:** [February 4, 2020, 2:54pm UTC](https://discourse.julialang.org/t/different-results-for-same-model-with-differentialequations-jl/34155 "2020-02-04T14:54:52Z")

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I am defining two ODEProblems, where they are both the same but the implementation is different. There is a parameter I specify for one problem directly inside the function and for the other problem as an argument to the…

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## [DifferentialEquations + RecursiveArrayTools Broadcasting / CuArrays Kernel compilation error --](https://discourse.julialang.org/t/differentialequations-recursivearraytools-broadcasting-cuarrays-kernel-compilation-error/34132)

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**Author:** [@cmarcotte](https://discourse.julialang.org/u/cmarcotte)\
**Replies:** 6\
**Last updated:** [February 4, 2020, 2:53pm UTC](https://discourse.julialang.org/t/differentialequations-recursivearraytools-broadcasting-cuarrays-kernel-compilation-error/34132 "2020-02-04T14:53:03Z")

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Hi, Finally have access to a CUDA capable GPU, so I’m trying to accelerate some finite-difference PDE solves using CuArrays and DifferentialEquations. I began with Chris’ simple reaction-diffusion demonstration here, a…

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## [Choosing a binary value with a certain probability (Biased random generator)](https://discourse.julialang.org/t/choosing-a-binary-value-with-a-certain-probability-biased-random-generator/34141)

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**Author:** [@HoldenCaulfield](https://discourse.julialang.org/u/HoldenCaulfield)\
**Replies:** 4\
**Last updated:** [February 4, 2020, 2:46pm UTC](https://discourse.julialang.org/t/choosing-a-binary-value-with-a-certain-probability-biased-random-generator/34141 "2020-02-04T14:46:49Z")

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I want to determine a random binary variable according to its probability. So let’s say that I have a binary variable with a probability of 70%, so I want it to become 1 with the probability of 70% and zero with a probab…

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## [JuMP precompiling error on an AWS EC2 Ubuntu server instance](https://discourse.julialang.org/t/jump-precompiling-error-on-an-aws-ec2-ubuntu-server-instance/33154)

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**Author:** [@newstatement](https://discourse.julialang.org/u/newstatement)\
**Replies:** 15\
**Last updated:** [February 4, 2020, 11:12am UTC](https://discourse.julialang.org/t/jump-precompiling-error-on-an-aws-ec2-ubuntu-server-instance/33154 "2020-02-04T11:12:35Z")

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I am trying to use an AWS EC2 instance (t2.micro with Ubuntu Server 18.04) to run an optimization model designed in JuMP. I’m using Julia v1.3.1 and when I try to load JuMP package a fail occurs at precompiling. Some one…

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## [How to plot next to each other and in rows small matrices as images (greyscale)](https://discourse.julialang.org/t/how-to-plot-next-to-each-other-and-in-rows-small-matrices-as-images-greyscale/34149)

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**Author:** [@Ujku\_KU](https://discourse.julialang.org/u/Ujku_KU)\
**Replies:** 4\
**Last updated:** [February 4, 2020, 8:21am UTC](https://discourse.julialang.org/t/how-to-plot-next-to-each-other-and-in-rows-small-matrices-as-images-greyscale/34149 "2020-02-04T08:21:49Z")

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Hi guys, my question is: how to plot next to each other and in rows small matrices as images (greyscale)? Thank you very much in advance for your support. Cheers. Ergnoor

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## [Using DifferentialEquations.jl to solve routine optimal control problems](https://discourse.julialang.org/t/using-differentialequations-jl-to-solve-routine-optimal-control-problems/34096)

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**Author:** [@Albert\_Zevelev](https://discourse.julialang.org/u/Albert_Zevelev)\
**Replies:** 7\
**Last updated:** [February 3, 2020, 8:38pm UTC](https://discourse.julialang.org/t/using-differentialequations-jl-to-solve-routine-optimal-control-problems/34096 "2020-02-03T20:38:18Z")

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I’m using DifferentialEquations.jl to solve a standard consumption-savings problem. I wanna see if there is a way to solve these issues before I submit feature-requests. using DifferentialEquations, BoundaryValueDiffEq…

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## [How to generate a random unitary matrix perfectly in Julia](https://discourse.julialang.org/t/how-to-generate-a-random-unitary-matrix-perfectly-in-julia/34102)

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**Author:** [@JunjieWu](https://discourse.julialang.org/u/JunjieWu)\
**Replies:** 10\
**Last updated:** [February 3, 2020, 4:18pm UTC](https://discourse.julialang.org/t/how-to-generate-a-random-unitary-matrix-perfectly-in-julia/34102 "2020-02-03T16:18:00Z")

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Dear friends, I am trying to implement a function that generates a random unitary matrix. However, I found that I met a precision issue. Is any idea how to solve this problem? using LinearAlgebra function RandomUnitar…

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## [How to minimize a function of single integer variable?](https://discourse.julialang.org/t/how-to-minimize-a-function-of-single-integer-variable/34115)

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**Author:** [@Gregstrq](https://discourse.julialang.org/u/Gregstrq)\
**Replies:** 2\
**Last updated:** [February 3, 2020, 4:08pm UTC](https://discourse.julialang.org/t/how-to-minimize-a-function-of-single-integer-variable/34115 "2020-02-03T16:08:22Z")

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Let’s suppose I have a function f(m): \\mathbb{N}\\rightarrow\\mathbb{R}. What method should I use to minimize it? The function is supposed to be smooth if we continue it from \\mathbb{N} to \[1,+\\infty). Also, it’s contin…

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## [Initializing a grid with coordinates on the GPU](https://discourse.julialang.org/t/initializing-a-grid-with-coordinates-on-the-gpu/34107)

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**Author:** [@stabbles](https://discourse.julialang.org/u/stabbles)\
**Replies:** 1\
**Last updated:** [February 3, 2020, 12:50pm UTC](https://discourse.julialang.org/t/initializing-a-grid-with-coordinates-on-the-gpu/34107 "2020-02-03T12:50:21Z")

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I’m trying to build a tensor A of size 3 x ℓ x m x n where A\[:, i, j, k\] is a 3D coordinate at (i, j, k) in a uniform grid for \[0, 1\]^3. On the CPU this code looks like this: function mesh(n) r = range(0.0f0, 1.0f0, …

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## [Blockdiag for dense matrices](https://discourse.julialang.org/t/blockdiag-for-dense-matrices/33941)

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**Author:** [@olof3](https://discourse.julialang.org/u/olof3)\
**Replies:** 10\
**Last updated:** [February 3, 2020, 9:51am UTC](https://discourse.julialang.org/t/blockdiag-for-dense-matrices/33941 "2020-02-03T09:51:42Z")

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Quite often I want to form dense block diagonal matrices from a few dense matrices. Is there an easy way to do this? There is blockdiag for sparse matrices: help?\> blockdiag search: blockdiag blockdiag(A...) Conca…

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## [Problem using Optim.optimize](https://discourse.julialang.org/t/problem-using-optim-optimize/33728)

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**Author:** [@Ujku\_KU](https://discourse.julialang.org/u/Ujku_KU)\
**Replies:** 36\
**Last updated:** [February 3, 2020, 5:00am UTC](https://discourse.julialang.org/t/problem-using-optim-optimize/33728 "2020-02-03T05:00:41Z")

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Hi guys, I am trying to translate a piece of code from Matlab to Julia, please see following first the original Matlab code: options = optimset('Largescale', 'off', 'MaxFunEvals', 500, 'GradObj','on', 'Display','notify'…

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## [Jump code errors](https://discourse.julialang.org/t/jump-code-errors/34090)

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**Author:** [@bandaya](https://discourse.julialang.org/u/bandaya)\
**Replies:** 2\
**Last updated:** [February 2, 2020, 9:23pm UTC](https://discourse.julialang.org/t/jump-code-errors/34090 "2020-02-02T21:23:52Z")

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Hi, I am new to Julia and I am having problems in running simple examples of Jump. I have given links to two examples below: Manual · MathOptInterface https://nbviewer.jupyter.org/github/JuliaOpt/juliaopt-notebooks/bl…

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## [How to use LBFGS to minimise the cost function for regularised logistic regression](https://discourse.julialang.org/t/how-to-use-lbfgs-to-minimise-the-cost-function-for-regularised-logistic-regression/34058)

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**Author:** [@PyDataBlog](https://discourse.julialang.org/u/PyDataBlog)\
**Replies:** 7\
**Last updated:** [February 2, 2020, 11:12am UTC](https://discourse.julialang.org/t/how-to-use-lbfgs-to-minimise-the-cost-function-for-regularised-logistic-regression/34058 "2020-02-02T11:12:33Z")

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I am currently stuck trying to utilize the Optim package in Julia in an attempt to minimize a cost function. The cost function is the cost function for an L2 regularised logistic regression. It is constructed as follows; …

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## [Implement berHu loss in Flux](https://discourse.julialang.org/t/implement-berhu-loss-in-flux/31707)

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**Author:** [@jchen975](https://discourse.julialang.org/u/jchen975)\
**Replies:** 9\
**Last updated:** [February 1, 2020, 9:06pm UTC](https://discourse.julialang.org/t/implement-berhu-loss-in-flux/31707 "2020-02-01T21:06:06Z")

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Hi, I was trying to build this loss function from this paper: I wanted to see if it outperforms squared L2 norm in another regression problem I’m working on. Here is my attempt: function berhu(x, y) x = model…

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