# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?page=324

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**Page:** 325

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## [Seeking a smart way to formulate an optimization problem](https://discourse.julialang.org/t/seeking-a-smart-way-to-formulate-an-optimization-problem/71056)

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**Author:** [@PeterSimon](https://discourse.julialang.org/u/PeterSimon)\
**Replies:** 4\
**Last updated:** [November 6, 2021, 10:12pm UTC](https://discourse.julialang.org/t/seeking-a-smart-way-to-formulate-an-optimization-problem/71056 "2021-11-06T22:12:04Z")

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I recently received tremendous help from this forum in setting up a JuMP optimization problem. I have a similar, but larger problem that I would like to attack, but it is too large to use the same methodology as previou…

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## [New Soss interface - request for feedback](https://discourse.julialang.org/t/new-soss-interface-request-for-feedback/65118)

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**Author:** [@cscherrer](https://discourse.julialang.org/u/cscherrer)\
**Replies:** 8\
**Last updated:** [November 6, 2021, 4:00pm UTC](https://discourse.julialang.org/t/new-soss-interface-request-for-feedback/65118 "2021-11-06T16:00:26Z")

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Hi, I’m working on extending Soss, and hoping I might get some design feedback. In the current release of Soss, a model is restricted to be a DAG. To do this, each line of the body of a model is required to be either of…

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## [Fast Legendre Transform?](https://discourse.julialang.org/t/fast-legendre-transform/68152)

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**Author:** [@Veenty](https://discourse.julialang.org/u/Veenty)\
**Replies:** 3\
**Last updated:** [November 6, 2021, 7:13am UTC](https://discourse.julialang.org/t/fast-legendre-transform/68152 "2021-11-06T07:13:04Z")

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Is anyone aware of a package that is able to do a Fast Legendre Transform similar to the one in chebfun (The fast discrete Legendre transform » Chebfun). The closest that I could find was something in FastTransform, whe…

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## [JuMP error for nonlinear optimization](https://discourse.julialang.org/t/jump-error-for-nonlinear-optimization/70983)

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**Author:** [@PeterSimon](https://discourse.julialang.org/u/PeterSimon)\
**Replies:** 17\
**Last updated:** [November 6, 2021, 2:21am UTC](https://discourse.julialang.org/t/jump-error-for-nonlinear-optimization/70983 "2021-11-06T02:21:25Z")

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I’m trying to set up a nonlinear optimization problem and I’m getting an error I don’t understand… import JuMP as J import Ipopt function smoothabs(x) # Smooth approximation to abs(x) k = 1000 f = 2/k f\*log…

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## [Set parameters to Gurobi](https://discourse.julialang.org/t/set-parameters-to-gurobi/70794)

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**Author:** [@wiz21b](https://discourse.julialang.org/u/wiz21b)\
**Replies:** 4\
**Last updated:** [November 5, 2021, 6:51pm UTC](https://discourse.julialang.org/t/set-parameters-to-gurobi/70794 "2021-11-05T18:51:10Z")

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Hello, I use Gurobi 9.1.2; Julia 1.6.2 and these packages: Gurobi v0.9.14 JuMP v0.21.10 (I’ve seen that the C API has changed) I try to tell Gurobi to use a specific optimizer (the PRIMAL (simplex) one): LP\_model =…

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## [Bug? Plots + pyplot()](https://discourse.julialang.org/t/bug-plots-pyplot/70940)

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**Author:** [@BLI](https://discourse.julialang.org/u/BLI)\
**Replies:** 7\
**Last updated:** [November 4, 2021, 11:47am UTC](https://discourse.julialang.org/t/bug-plots-pyplot/70940 "2021-11-04T11:47:21Z")

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I’m on Windows 11 (64bit), latest update as of now. I use Julia v1.6.3, latest update as of today with all packages. When I do simple plots using the pyplot() backend, my Jupyter notebook crashes with the following erro…

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## [Namespace problems when running Optim in parallel?](https://discourse.julialang.org/t/namespace-problems-when-running-optim-in-parallel/2275)

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**Author:** [@Elrod](https://discourse.julialang.org/u/Elrod)\
**Replies:** 2\
**Last updated:** [November 5, 2021, 10:11am UTC](https://discourse.julialang.org/t/namespace-problems-when-running-optim-in-parallel/2275 "2021-11-05T10:11:33Z")

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Hi, I keep running into errors such as: ERROR: LoadError: On worker 2: MethodError: no method matching minimizer(::Optim.MultivariateOptimizationResults{Float64,1,Optim.NewtonTrustRegion{Float64}}) or, the comical E…

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## [AmplNLWriter no longer works with JuMP](https://discourse.julialang.org/t/amplnlwriter-no-longer-works-with-jump/70740)

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**Author:** [@optimist](https://discourse.julialang.org/u/optimist)\
**Replies:** 10\
**Last updated:** [November 4, 2021, 11:52pm UTC](https://discourse.julialang.org/t/amplnlwriter-no-longer-works-with-jump/70740 "2021-11-04T23:52:11Z")

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I was using AmplNLWriter with Ipopt\_jll, but it stopped working when I installed MadNLP. I have removed all my packages and reinstalled (excluding MaNLP), but I have not been able to make AmplNLWriter to work. The error …

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## [Length and setting of ticks](https://discourse.julialang.org/t/length-and-setting-of-ticks/70952)

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**Author:** [@mixstam1453](https://discourse.julialang.org/u/mixstam1453)\
**Replies:** 2\
**Last updated:** [November 4, 2021, 7:52pm UTC](https://discourse.julialang.org/t/length-and-setting-of-ticks/70952 "2021-11-04T19:52:35Z")

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hello, i am new in Plots.jl and i would like to put ticks in all my axis of the plot with framestyle=:box . Here is my code with the default function: x = 0:0.1:2pi ; y1 = cos.(x) default(fontfamily ="New Century Scho…

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## [Broadcasting over a Flux.DataLoader](https://discourse.julialang.org/t/broadcasting-over-a-flux-dataloader/70414)

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**Author:** [@austinbean](https://discourse.julialang.org/u/austinbean)\
**Replies:** 11\
**Last updated:** [November 4, 2021, 6:59pm UTC](https://discourse.julialang.org/t/broadcasting-over-a-flux-dataloader/70414 "2021-11-04T18:59:00Z")

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Apologies for this question since I’ve had a lot of trouble producing a MWE (which I don’t have). I’m working on an RNN using text data (each observation is a sentence - each word in each sentence is mapped to a word em…

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## [Tutorial on Coupling Jumps](https://discourse.julialang.org/t/tutorial-on-coupling-jumps/70957)

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**Author:** [@tom-plaa](https://discourse.julialang.org/u/tom-plaa)\
**Replies:** 0\
**Last updated:** [November 4, 2021, 2:42pm UTC](https://discourse.julialang.org/t/tutorial-on-coupling-jumps/70957 "2021-11-04T14:42:36Z")

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Didn’t create an issue on the repo because this might be just my interpretation being wrong. I am trying to run code based on the tutorial at Jump Diffusion page. It mentions that this is supposed to be a Cox process (…

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## [Weights in gaussian process](https://discourse.julialang.org/t/weights-in-gaussian-process/70646)

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**Author:** [@jzr](https://discourse.julialang.org/u/jzr)\
**Replies:** 7\
**Last updated:** [November 4, 2021, 1:51pm UTC](https://discourse.julialang.org/t/weights-in-gaussian-process/70646 "2021-11-04T13:51:07Z")

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I have a model like @willtebbutt’s TemporalGPs example https://github.com/JuliaGaussianProcesses/TemporalGPs.jl#learning-kernel-parameters-with-optimjl-parameterhandlingjl-and-zygotejl In my dataset, different observati…

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## [Differentiate through solve for a subset of parameters](https://discourse.julialang.org/t/differentiate-through-solve-for-a-subset-of-parameters/70869)

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**Author:** [@hexaeder](https://discourse.julialang.org/u/hexaeder)\
**Replies:** 5\
**Last updated:** [November 4, 2021, 11:07am UTC](https://discourse.julialang.org/t/differentiate-through-solve-for-a-subset-of-parameters/70869 "2021-11-04T11:07:33Z")

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If I pass a vector of dual numbers as parameters, the solver will recocnize the dual numbers and provide a vector dx\<:Vector{Dual...} to my diff eq function. In my problem I have several parameters I want to tune but a…

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## [Tridiagonal Toeplitz matrix complex eigenvalues instead of real](https://discourse.julialang.org/t/tridiagonal-toeplitz-matrix-complex-eigenvalues-instead-of-real/70892)

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**Author:** [@jamblejoe](https://discourse.julialang.org/u/jamblejoe)\
**Replies:** 7\
**Last updated:** [November 4, 2021, 10:08am UTC](https://discourse.julialang.org/t/tridiagonal-toeplitz-matrix-complex-eigenvalues-instead-of-real/70892 "2021-11-04T10:08:17Z")

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The spectrum of tridiagonal Toeplitz matrices is known analytically (Tridiagonal-Toeplitz-Matrix – Wikipedia) and is (for non-zero off-diagonals) simple and real. Julia’s eigen function returns for small non-symmetric To…

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## [2 problems with Gaston.jl](https://discourse.julialang.org/t/2-problems-with-gaston-jl/70907)

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**Author:** [@trg818](https://discourse.julialang.org/u/trg818)\
**Replies:** 3\
**Last updated:** [November 4, 2021, 12:46am UTC](https://discourse.julialang.org/t/2-problems-with-gaston-jl/70907 "2021-11-04T00:46:05Z")

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As it doesn’t (yet?) seem to be possible to create a plot with two different x-axes and two different y-axes with Plots, I decided to give Gaston a try, because it would give me an interface to my good old Gnuplot, where…

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## [MultivariateStats - Factor Analysis not working for the :cm method?](https://discourse.julialang.org/t/multivariatestats-factor-analysis-not-working-for-the-cm-method/70418)

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**Author:** [@julio.ca2020](https://discourse.julialang.org/u/julio.ca2020)\
**Replies:** 1\
**Last updated:** [November 3, 2021, 10:48pm UTC](https://discourse.julialang.org/t/multivariatestats-factor-analysis-not-working-for-the-cm-method/70418 "2021-11-03T22:48:08Z")

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I am doing a factor analysis and I’ve noticed that the method :em works in all cases but not the :cm (default). Why this? This works for example: using MultivariateStats X = \[0.635098 0.548183 0.211851 0.171408 0…

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## [Graph from Sparse Matrix](https://discourse.julialang.org/t/graph-from-sparse-matrix/70894)

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**Author:** [@rachithaiyappa](https://discourse.julialang.org/u/rachithaiyappa)\
**Replies:** 2\
**Last updated:** [November 3, 2021, 6:39pm UTC](https://discourse.julialang.org/t/graph-from-sparse-matrix/70894 "2021-11-03T18:39:11Z")

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How can I generate a Graph from a SparseMatrixCSC and then convert it into an undirected Light Graph?

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## [Plotly.js - stacked bars in subplots](https://discourse.julialang.org/t/plotly-js-stacked-bars-in-subplots/60856)

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**Author:** [@stej](https://discourse.julialang.org/u/stej)\
**Replies:** 6\
**Last updated:** [November 3, 2021, 10:53am UTC](https://discourse.julialang.org/t/plotly-js-stacked-bars-in-subplots/60856 "2021-11-03T10:53:29Z")

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Hi all, I’m trying to plot stacked bars with PlotlyJS. It looks ok, when I use just one plot, but when I combine two plots together, the bars are no longer stacked. Example: using PlotlyJS, Dates dates = \[Date(2021, …

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## [Variable sequence length RNN in Flux](https://discourse.julialang.org/t/variable-sequence-length-rnn-in-flux/70715)

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**Author:** [@paalon](https://discourse.julialang.org/u/paalon)\
**Replies:** 2\
**Last updated:** [November 3, 2021, 9:57am UTC](https://discourse.julialang.org/t/variable-sequence-length-rnn-in-flux/70715 "2021-11-03T09:57:18Z")

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How to implement RNN for variable sequence length data with minibatching in Flux? According to Flux doc, In Flux, those 3 dimensions are provided through a vector of seq length containing a matrix (features, samples) …

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## [Normalize the solution during the integration by differentialequations.jl](https://discourse.julialang.org/t/normalize-the-solution-during-the-integration-by-differentialequations-jl/70845)

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**Author:** [@TravellingLight6](https://discourse.julialang.org/u/TravellingLight6)\
**Replies:** 1\
**Last updated:** [November 3, 2021, 5:38am UTC](https://discourse.julialang.org/t/normalize-the-solution-during-the-integration-by-differentialequations-jl/70845 "2021-11-03T05:38:25Z")

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I usually come to solve outwards ode like schrodinger equation under columb potential and I recently realize that the initial condition and time span affect the stability of the solution as posted as following: using Di…

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## [Restricting "active" joints in RigidBodyDynamics.jl](https://discourse.julialang.org/t/restricting-active-joints-in-rigidbodydynamics-jl/70829)

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**Author:** [@benjamin-macadam](https://discourse.julialang.org/u/benjamin-macadam)\
**Replies:** 0\
**Last updated:** [November 2, 2021, 10:19pm UTC](https://discourse.julialang.org/t/restricting-active-joints-in-rigidbodydynamics-jl/70829 "2021-11-02T22:19:15Z")

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Hi there, I have been using RigidBodyDynamics.jl to do some simulations with robotics for about a month or so. I’m finding performance for some of my simulations really suffers when I use the full collection of joints i…

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## [Can I use opensource drivers to code in Cuda?](https://discourse.julialang.org/t/can-i-use-opensource-drivers-to-code-in-cuda/70682)

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**Author:** [@anon69491625](https://discourse.julialang.org/u/anon69491625)\
**Replies:** 3\
**Last updated:** [November 2, 2021, 9:57pm UTC](https://discourse.julialang.org/t/can-i-use-opensource-drivers-to-code-in-cuda/70682 "2021-11-02T21:57:57Z")

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Hi all can I use xserver-xorg-video-nouveau v 1:1.0.16.1 display drivers to code in Cuda and NOT the official nvidia 470? I have had a bit of bad news. I am using linux mint 20.2 ( based on Ubuntu) and am using open so…

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## [Correct version of cuda.jl for Quadro K4200](https://discourse.julialang.org/t/correct-version-of-cuda-jl-for-quadro-k4200/70744)

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**Author:** [@jamaas](https://discourse.julialang.org/u/jamaas)\
**Replies:** 5\
**Last updated:** [November 2, 2021, 4:52pm UTC](https://discourse.julialang.org/t/correct-version-of-cuda-jl-for-quadro-k4200/70744 "2021-11-02T16:52:22Z")

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I’d like to learn how to use gpu computing with my pc, runs on ubuntu linux and has a Quadro K4200 gpu which only has a compute capability of 3.0. What version of cuda.jl should I be trying to install that will work wi…

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## [Multiple plots: some refinements](https://discourse.julialang.org/t/multiple-plots-some-refinements/64800)

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**Author:** [@marcobonici](https://discourse.julialang.org/u/marcobonici)\
**Replies:** 25\
**Last updated:** [November 2, 2021, 4:33pm UTC](https://discourse.julialang.org/t/multiple-plots-some-refinements/64800 "2021-11-02T16:33:34Z")

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Hi to everybody, I am trying to make some plots for my research (Fisher contour plots) using Plots.jl. I am quite satisfied with the results I have obtained (in a very short amount of time!) FisherMatrix = \[16523.02 33…

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## [Computing the Lyapunov exponent of the Hénon map with DynamicalSystems.jl](https://discourse.julialang.org/t/computing-the-lyapunov-exponent-of-the-henon-map-with-dynamicalsystems-jl/70810)

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**Author:** [@NoFishLikeIan](https://discourse.julialang.org/u/NoFishLikeIan)\
**Replies:** 2\
**Last updated:** [November 2, 2021, 3:25pm UTC](https://discourse.julialang.org/t/computing-the-lyapunov-exponent-of-the-henon-map-with-dynamicalsystems-jl/70810 "2021-11-02T15:25:56Z")

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Issue I am trying to compute the Lyapunov exponent of the Hénon map with b = 0.3 and a = 1.8 but the lyapunov function from DynamicalSystems.jl seems to not converge. Is there something I am doing wrong or is this expect…

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## [Why does my neural net not learn](https://discourse.julialang.org/t/why-does-my-neural-net-not-learn/70603)

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**Author:** [@Marius\_123](https://discourse.julialang.org/u/Marius_123)\
**Replies:** 3\
**Last updated:** [November 2, 2021, 10:36am UTC](https://discourse.julialang.org/t/why-does-my-neural-net-not-learn/70603 "2021-11-02T10:36:23Z")

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using Flux, Statistics using Flux.Data: DataLoader using Flux: @epochs using Flux.Losses: huber\_loss, tversky\_loss, mse using Base: @kwdef using CUDA function Data\_importer() train\_x = \[0.0 0.0 0.0 0.0; 9.178257595538…

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## [Makie.jl: right align colorbar ticklabel](https://discourse.julialang.org/t/makie-jl-right-align-colorbar-ticklabel/70787)

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**Author:** [@Kevin\_Kleinbeck](https://discourse.julialang.org/u/Kevin_Kleinbeck)\
**Replies:** 0\
**Last updated:** [November 2, 2021, 8:35am UTC](https://discourse.julialang.org/t/makie-jl-right-align-colorbar-ticklabel/70787 "2021-11-02T08:35:58Z")

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Cheers. Consider the figure: I aim to align the tick labels of the colorbar on the right. This happens with ticklabelalign = (:right, :center); however then the tick labels lie within the colorbar. To fix this, I r…

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## [How to remove the vertex in Graphs or LightGraphs?](https://discourse.julialang.org/t/how-to-remove-the-vertex-in-graphs-or-lightgraphs/70789)

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**Author:** [@yewalenikhil65](https://discourse.julialang.org/u/yewalenikhil65)\
**Replies:** 3\
**Last updated:** [November 2, 2021, 10:13am UTC](https://discourse.julialang.org/t/how-to-remove-the-vertex-in-graphs-or-lightgraphs/70789 "2021-11-02T10:13:13Z")

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julia\> myedges = \[ 1 =\> 2, 1 =\> 3, 2 =\> 1, 2 =\> 3, 3 =\> 1, 3 =\> 2, 3 =\> 4, 4 =\> 3, 4 =\> 8, 4 =\> 13, 5 =\> 6, 6 =\> 5, 7 =\> 8,…

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## [Solving semilinear ODE with changing linear operator](https://discourse.julialang.org/t/solving-semilinear-ode-with-changing-linear-operator/70747)

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**Author:** [@wsshin](https://discourse.julialang.org/u/wsshin)\
**Replies:** 3\
**Last updated:** [November 1, 2021, 8:47pm UTC](https://discourse.julialang.org/t/solving-semilinear-ode-with-changing-linear-operator/70747 "2021-11-01T20:47:19Z")

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I am trying to solve a semilinear ODE whose linear operator depends on the solution: du/dt = A(u) u + f(u,t). The “linear” operator A(u) is diagonal. I am wondering what is the best approach to solve this problem by Di…

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## [Hypatia -- JuMP](https://discourse.julialang.org/t/hypatia-jump/70717)

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**Author:** [@geo](https://discourse.julialang.org/u/geo)\
**Replies:** 4\
**Last updated:** [November 2, 2021, 6:12am UTC](https://discourse.julialang.org/t/hypatia-jump/70717 "2021-11-02T06:12:07Z")

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I know that JuMP does not support BigFloat; however Hypatia does. Is it possible to define a problem in JuMP, in Float64, but cause Hypatia to carry out the optimization in BigFloat? I am working on a problem, where the …

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