# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=380

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**Page:** 381

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## [Singularity, ERROR: Unable to find compatible target in system image](https://discourse.julialang.org/t/singularity-error-unable-to-find-compatible-target-in-system-image/57619)

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**Author:** [@Perrin\_Meyer](https://discourse.julialang.org/u/Perrin_Meyer)\
**Replies:** 3\
**Last updated:** [March 21, 2021, 12:00am UTC](https://discourse.julialang.org/t/singularity-error-unable-to-find-compatible-target-in-system-image/57619 "2021-03-21T00:00:55Z")

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I’m trying to compile a Singularity container for running on a HPC cluster. My container works on my laptop (where I build it), but when I transfer it over to the cluster, I get a: ERROR: Unable to find compatible targ…

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## [TextAnalysis 0.7.2 - where to find SentimentAnalyzer()](https://discourse.julialang.org/t/textanalysis-0-7-2-where-to-find-sentimentanalyzer/57612)

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**Author:** [@julio.ca2020](https://discourse.julialang.org/u/julio.ca2020)\
**Replies:** 4\
**Last updated:** [March 20, 2021, 7:29pm UTC](https://discourse.julialang.org/t/textanalysis-0-7-2-where-to-find-sentimentanalyzer/57612 "2021-03-20T19:29:53Z")

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In the documentation for TextAnalysis 0.7.2, the function SentimentAnalyzer() is available. I do not find in the code. Where is it? What am I doing wrong? https://juliahub.com/docs/TextAnalysis/5Mwet/0.7.2/features/

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## [Apply hessian of neural network to array](https://discourse.julialang.org/t/apply-hessian-of-neural-network-to-array/57602)

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**Author:** [@Sunny](https://discourse.julialang.org/u/Sunny)\
**Replies:** 2\
**Last updated:** [March 20, 2021, 2:35pm UTC](https://discourse.julialang.org/t/apply-hessian-of-neural-network-to-array/57602 "2021-03-20T14:35:37Z")

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I can simply take a hessian of some function in multiple points hess = x -\> (Zygote.hessian.(x-\>sum(x.^3), x)) hess(rand(2,3)) 2×3 Array{Float64,2}: 2.67795 3.8318 4.9022 0.216379 5.67439 4.96389 But I’m alway…

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## [Getting CartesianIndices to propagate](https://discourse.julialang.org/t/getting-cartesianindices-to-propagate/57315)

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**Author:** [@RainerHeintzmann](https://discourse.julialang.org/u/RainerHeintzmann)\
**Replies:** 8\
**Last updated:** [March 20, 2021, 11:43am UTC](https://discourse.julialang.org/t/getting-cartesianindices-to-propagate/57315 "2021-03-20T11:43:33Z")

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Julia (here 1.6RC1 on Windows 10) has a number of mechanism to calculate with positions inside an array such as ranges like (1:10) or generators or via CartesianIndices(x). Yet they all seem to not automatically propagat…

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## [Stff System](https://discourse.julialang.org/t/stff-system/57569)

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**Author:** [@Manisha\_07](https://discourse.julialang.org/u/Manisha_07)\
**Replies:** 2\
**Last updated:** [March 19, 2021, 10:52pm UTC](https://discourse.julialang.org/t/stff-system/57569 "2021-03-19T22:52:04Z")

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I am very new to Julia While solving ODE i have come across Stiff system Wat does the Stiff system means.

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## [No method matching zero(::Type{Array{Float64,2}})](https://discourse.julialang.org/t/no-method-matching-zero-type-array-float64-2/57538)

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**Author:** [@Shazman](https://discourse.julialang.org/u/Shazman)\
**Replies:** 13\
**Last updated:** [March 19, 2021, 9:29pm UTC](https://discourse.julialang.org/t/no-method-matching-zero-type-array-float64-2/57538 "2021-03-19T21:29:20Z")

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Hi, I am using Julia to solve the equation below, where XS is a large matrix and XT is a transpose version of XS. LamI is a diagonal matrix and RHS is a vector. using DelimitedFiles using LinearAlgebra XS = readdl…

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## [Poisson changepoint model: UK Coal Mining Disasters](https://discourse.julialang.org/t/poisson-changepoint-model-uk-coal-mining-disasters/57470)

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**Author:** [@gsinha](https://discourse.julialang.org/u/gsinha)\
**Replies:** 10\
**Last updated:** [March 19, 2021, 8:32pm UTC](https://discourse.julialang.org/t/poisson-changepoint-model-uk-coal-mining-disasters/57470 "2021-03-19T20:32:36Z")

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Hi: In an effort to learn Turing, I set out to replicate the UK Coal Mining disasters example. I think I’ve managed to successfully replicate the results - this is what I did. using Turing using Distributions using Dis…

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## [Fast Hessian size increase](https://discourse.julialang.org/t/fast-hessian-size-increase/57560)

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**Author:** [@Sunny](https://discourse.julialang.org/u/Sunny)\
**Replies:** 6\
**Last updated:** [March 19, 2021, 6:58pm UTC](https://discourse.julialang.org/t/fast-hessian-size-increase/57560 "2021-03-19T18:58:15Z")

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I’d like to compute the Hessian for array values and to get some array with dimension (2,2) but instead I got this julia\> hessian(x -\> sum(x.^3), \[1 2; 3 4\]) # uses linear indexing of x 4×4 Array{$Int,2}: 6 0 0 …

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## [Why is SUM always used in differentiation?](https://discourse.julialang.org/t/why-is-sum-always-used-in-differentiation/57559)

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**Author:** [@Sunny](https://discourse.julialang.org/u/Sunny)\
**Replies:** 3\
**Last updated:** [March 19, 2021, 6:54pm UTC](https://discourse.julialang.org/t/why-is-sum-always-used-in-differentiation/57559 "2021-03-19T18:54:55Z")

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I’ve seen a lot of examples where the output of a NN or any function during the differentiation is preprocessed with sum operator. For example this: julia\> hessian(x -\> sum(x.^3), \[1 2; 3 4\]) # uses linear indexing of …

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## [Is there a power flow formulation that considers branches power transfer limit in PowerModels.jl?](https://discourse.julialang.org/t/is-there-a-power-flow-formulation-that-considers-branches-power-transfer-limit-in-powermodels-jl/57548)

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**Author:** [@RaulRib](https://discourse.julialang.org/u/RaulRib)\
**Replies:** 2\
**Last updated:** [March 19, 2021, 3:48pm UTC](https://discourse.julialang.org/t/is-there-a-power-flow-formulation-that-considers-branches-power-transfer-limit-in-powermodels-jl/57548 "2021-03-19T15:48:56Z")

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Hello, I am working on a project where I investigate the behavior of power systems with congested lines.When running run\_ac\_pf or run\_dc\_pf, I notice that some branches resulting power flow exceed their limit. Searching…

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## [Constant linear equation d/dt x=Ax with DifferentialEquations.jl](https://discourse.julialang.org/t/constant-linear-equation-d-dt-x-ax-with-differentialequations-jl/57532)

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**Author:** [@jamblejoe](https://discourse.julialang.org/u/jamblejoe)\
**Replies:** 4\
**Last updated:** [March 19, 2021, 12:57pm UTC](https://discourse.julialang.org/t/constant-linear-equation-d-dt-x-ax-with-differentialequations-jl/57532 "2021-03-19T12:57:31Z")

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In Non-autonomous Linear ODE / Lie Group ODE Solvers · DifferentialEquations.jl are examples for solving d/dt x = A(t) x, time-dependent A, or state dependent A(x), d/dt x = A(x)x, but no example for just constant A. How…

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## [How to eliminate empty columns](https://discourse.julialang.org/t/how-to-eliminate-empty-columns/57484)

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**Author:** [@Laco\_Kovac](https://discourse.julialang.org/u/Laco_Kovac)\
**Replies:** 4\
**Last updated:** [March 19, 2021, 12:36pm UTC](https://discourse.julialang.org/t/how-to-eliminate-empty-columns/57484 "2021-03-19T12:36:22Z")

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Here is roughly the code which exports data from the table to CSV String using LibPQ, DataFrames, CSV executeResult = execute(conn, "SELECT c1, c2, c3, c4, c5 FROM some\_table WHERE some\_id = '$someId'") if (LibPQ.libpq…

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## [Searching for a simple polynomial curve fitting example](https://discourse.julialang.org/t/searching-for-a-simple-polynomial-curve-fitting-example/5302)

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**Author:** [@J\_T](https://discourse.julialang.org/u/J_T)\
**Replies:** 6\
**Last updated:** [March 19, 2021, 5:10am UTC](https://discourse.julialang.org/t/searching-for-a-simple-polynomial-curve-fitting-example/5302 "2021-03-19T05:10:51Z")

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Im new to mathematical optimisation, so I’m looking for a simple example I can learn from … My (initial) problem looks like 1000 cartesian points in Float16 I want to find a polynomial p(x) (to be evaluated in Float16…

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## [Plots... with Dates along abscissa axis?](https://discourse.julialang.org/t/plots-with-dates-along-abscissa-axis/24454)

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**Author:** [@BLI](https://discourse.julialang.org/u/BLI)\
**Replies:** 7\
**Last updated:** [March 19, 2021, 8:52am UTC](https://discourse.julialang.org/t/plots-with-dates-along-abscissa-axis/24454 "2021-03-19T08:52:31Z")

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I have some data where I want to plot some quantity (ordinate) against dates (abscissa). The abscissa data are in Dates.Date() format. When plotting (I tested Plots with unicodeplots back-end), the dates are given in sec…

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## [How to speed up this DataFrame operation](https://discourse.julialang.org/t/how-to-speed-up-this-dataframe-operation/57505)

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**Author:** [@amrods](https://discourse.julialang.org/u/amrods)\
**Replies:** 11\
**Last updated:** [March 19, 2021, 6:11am UTC](https://discourse.julialang.org/t/how-to-speed-up-this-dataframe-operation/57505 "2021-03-19T06:11:08Z")

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I have a DataFrame and I would like to store the data in an Array. This constructs the DataFrame: using DataFrames using DataFramesMeta using StatsBase n = 9^2\*2^2\*6^2\*42 const df = crossjoin( DataFram…

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## [Hugely different solutions between JuMP/Ipopt and a commercial solver](https://discourse.julialang.org/t/hugely-different-solutions-between-jump-ipopt-and-a-commercial-solver/57218)

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**Author:** [@askvorts](https://discourse.julialang.org/u/askvorts)\
**Replies:** 4\
**Last updated:** [March 19, 2021, 12:34am UTC](https://discourse.julialang.org/t/hugely-different-solutions-between-jump-ipopt-and-a-commercial-solver/57218 "2021-03-19T00:34:34Z")

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I am using a commom portfolio optimization problem (maximizing the Sharpe ratio) to improve my knowledge of non-linear optimization using JuMP and Ipopt. The objective is Max pmean' w / sqrt(w' pcov w) subject to bound a…

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## [Save additional quantities using DifferentialEquations.jl pkg](https://discourse.julialang.org/t/save-additional-quantities-using-differentialequations-jl-pkg/34011)

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**Author:** [@moesphere](https://discourse.julialang.org/u/moesphere)\
**Replies:** 26\
**Last updated:** [March 18, 2021, 7:44pm UTC](https://discourse.julialang.org/t/save-additional-quantities-using-differentialequations-jl-pkg/34011 "2021-03-18T19:44:25Z")

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Within my ODE function additional quantities are calculated which I would like to save to extract them later for e.g. inspection or plotting. There is the approach with the SavingCallback; however, the save\_func(u, t, i…

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## [Expression manipulation in Symbolics](https://discourse.julialang.org/t/expression-manipulation-in-symbolics/57486)

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**Author:** [@klaff](https://discourse.julialang.org/u/klaff)\
**Replies:** 4\
**Last updated:** [March 18, 2021, 7:05pm UTC](https://discourse.julialang.org/t/expression-manipulation-in-symbolics/57486 "2021-03-18T19:05:54Z")

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Playing with Symbolics like so: julia\> @variables a b c (a, b, c) julia\> par(x,y) = 1/(1/x+1/y) par (generic function with 1 method) julia\> ex1 = par(a, par(b,c)) (a^-1 + ((b^-1 + c^-1)^-1)^-1)^-1 julia\> simplify(ex1…

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## [How to debug IDA](https://discourse.julialang.org/t/how-to-debug-ida/54643)

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**Author:** [@ohmsweetohm1](https://discourse.julialang.org/u/ohmsweetohm1)\
**Replies:** 1\
**Last updated:** [March 18, 2021, 6:26pm UTC](https://discourse.julialang.org/t/how-to-debug-ida/54643 "2021-03-18T18:26:07Z")

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I have a large DAE problem (102 variables) and have trouble finding consistent initial conditions. I always get: \[IDAS ERROR\] IDACalcIC Newton/Linesearch algorithm failed to converge. Is there a way to debug this?

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## [Can you solve a NeuralODEMM on GPU?](https://discourse.julialang.org/t/can-you-solve-a-neuralodemm-on-gpu/57480)

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**Author:** [@bad\_at\_math](https://discourse.julialang.org/u/bad_at_math)\
**Replies:** 0\
**Last updated:** [March 18, 2021, 3:03pm UTC](https://discourse.julialang.org/t/can-you-solve-a-neuralodemm-on-gpu/57480 "2021-03-18T15:03:01Z")

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I’m trying to solve a neural ODE with a mass matrix using CUDA. Is this possible, or are the required solvers not GPU-compatible? I can define a NeuralODEMM with a CuArray Chain, but I get the error ERROR: LoadError: sca…

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## [Why does DiffEqFlux.NeuralODEMM require a constraint equation and a mass matrix?](https://discourse.julialang.org/t/why-does-diffeqflux-neuralodemm-require-a-constraint-equation-and-a-mass-matrix/57428)

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**Author:** [@bad\_at\_math](https://discourse.julialang.org/u/bad_at_math)\
**Replies:** 3\
**Last updated:** [March 18, 2021, 2:24pm UTC](https://discourse.julialang.org/t/why-does-diffeqflux-neuralodemm-require-a-constraint-equation-and-a-mass-matrix/57428 "2021-03-18T14:24:40Z")

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Hello everyone! I’m looking at the “Enforcing physical constraints via universal differential-algebraic equations” example (https://diffeqflux.sciml.ai/dev/examples/physical\_constraints/), which trains a neural ordinary…

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## [Yet Another Component Example](https://discourse.julialang.org/t/yet-another-component-example/57318)

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**Author:** [@lungd](https://discourse.julialang.org/u/lungd)\
**Replies:** 1\
**Last updated:** [March 18, 2021, 12:13pm UTC](https://discourse.julialang.org/t/yet-another-component-example/57318 "2021-03-18T12:13:47Z")

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As far as I know, there are some WIP tutorials describing how to create components and how they can be merged. I was not sure where to put the following, maybe it would fit better into an existing github issue (e.g. Conn…

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## [Neuroscientists using DifferentialEquations.jl ecosystem?](https://discourse.julialang.org/t/neuroscientists-using-differentialequations-jl-ecosystem/31871)

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**Author:** [@wsphillips](https://discourse.julialang.org/u/wsphillips)\
**Replies:** 25\
**Last updated:** [March 18, 2021, 11:32am UTC](https://discourse.julialang.org/t/neuroscientists-using-differentialequations-jl-ecosystem/31871 "2021-03-18T11:32:44Z")

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I am curious who might be working with the DiffEq packages to do single neuron cell modeling up to small network simulations using Hodgkin Huxley or similar models, either single or multi-compartment, etc. If you’re out…

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## [Implementing the hydrogen atom?](https://discourse.julialang.org/t/implementing-the-hydrogen-atom/57455)

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**Author:** [@volkerkarle](https://discourse.julialang.org/u/volkerkarle)\
**Replies:** 0\
**Last updated:** [March 18, 2021, 10:15am UTC](https://discourse.julialang.org/t/implementing-the-hydrogen-atom/57455 "2021-03-18T10:15:27Z")

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Hi folks, Is there a package dealing with problems from atomic physics i.e. an implementation of the hydrogen wave function, relativistic corrections etc. ? I know there is UnitfulAtomic.jl, but that is only for the cor…

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## [Distributed, AllReduce, and Distributed Training](https://discourse.julialang.org/t/distributed-allreduce-and-distributed-training/56110)

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**Author:** [@asaxton](https://discourse.julialang.org/u/asaxton)\
**Replies:** 1\
**Last updated:** [March 18, 2021, 9:56am UTC](https://discourse.julialang.org/t/distributed-allreduce-and-distributed-training/56110 "2021-03-18T09:56:51Z")

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Continuing the discussion from Julia Distributed, AllReduce, and Distributed Training: I’m working with Distributed Julia on multiple hosts and want to write some code that does distributed training with a machine learn…

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## [Is it time for a native Julia LP(Simplex) solver?](https://discourse.julialang.org/t/is-it-time-for-a-native-julia-lp-simplex-solver/21639)

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**Author:** [@ndinsmore](https://discourse.julialang.org/u/ndinsmore)\
**Replies:** 44\
**Last updated:** [March 18, 2021, 8:58am UTC](https://discourse.julialang.org/t/is-it-time-for-a-native-julia-lp-simplex-solver/21639 "2021-03-18T08:58:57Z")

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For the last few months, I have been coming up to speed on both Linear Programming with Jump.jl using Clp.jl, Cbc.jl, and GLPK.jl. I have made some minor PRs to a few of the projects in order to improve the capability t…

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## [Accessing variables in a ModelingToolkit system](https://discourse.julialang.org/t/accessing-variables-in-a-modelingtoolkit-system/57249)

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**Author:** [@Dhruva2](https://discourse.julialang.org/u/Dhruva2)\
**Replies:** 9\
**Last updated:** [March 18, 2021, 5:59am UTC](https://discourse.julialang.org/t/accessing-variables-in-a-modelingtoolkit-system/57249 "2021-03-18T05:59:12Z")

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First off, the new functionality for connecting systems in ModelingToolkit is really powerful, awesome job! I have a few issues with it that I can’t solve, however… Suppose I have a ModelingToolkit ODESystem od::ODESy…

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## [Dash.jl - Plotly mapbox layer/trace support](https://discourse.julialang.org/t/dash-jl-plotly-mapbox-layer-trace-support/57438)

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**Author:** [@spcogg](https://discourse.julialang.org/u/spcogg)\
**Replies:** 0\
**Last updated:** [March 18, 2021, 5:05am UTC](https://discourse.julialang.org/t/dash-jl-plotly-mapbox-layer-trace-support/57438 "2021-03-18T05:05:54Z")

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Does anyone know if the julia Dash.jl interface currently supports mapbox layers , specifically, the scattermapbox trace I can see references to it in code, e.g. the docstrings for the dcc\_graph function, but i can’t s…

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## [Generic edgeMap function for graph algorithms like Bellman-Ford](https://discourse.julialang.org/t/generic-edgemap-function-for-graph-algorithms-like-bellman-ford/57416)

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**Author:** [@Aje12](https://discourse.julialang.org/u/Aje12)\
**Replies:** 0\
**Last updated:** [March 17, 2021, 9:17pm UTC](https://discourse.julialang.org/t/generic-edgemap-function-for-graph-algorithms-like-bellman-ford/57416 "2021-03-17T21:17:49Z")

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Hi everyone, Apologies for this being a long one. I am working with the bellman ford algorithm from lightgraphs.jl but having an issue with some of my functions. My intension behind this is to have a general mapping fun…

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## [In Makie, when should a function accept \`fig\[1,1\]\` as input, vs an \`Axis\`?](https://discourse.julialang.org/t/in-makie-when-should-a-function-accept-fig-1-1-as-input-vs-an-axis/57399)

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**Author:** [@ericphanson](https://discourse.julialang.org/u/ericphanson)\
**Replies:** 1\
**Last updated:** [March 17, 2021, 5:26pm UTC](https://discourse.julialang.org/t/in-makie-when-should-a-function-accept-fig-1-1-as-input-vs-an-axis/57399 "2021-03-17T17:26:28Z")

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I don’t really when to use an Axis vs indexing like fig\[1,1\] . If I’m writing a function to make part of a plot, should I be passing it fig\[1,1\] or an axis? should the function be making the axis and returning it? From @…

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