# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=488

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**Page:** 489

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## [ForwardDiff question](https://discourse.julialang.org/t/forwarddiff-question/26712)

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**Author:** [@mbeach42](https://discourse.julialang.org/u/mbeach42)\
**Replies:** 6\
**Last updated:** [July 26, 2019, 4:22am UTC](https://discourse.julialang.org/t/forwarddiff-question/26712 "2019-07-26T04:22:42Z")

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I’m having trouble debugging why ForwardDiff is not working for my function. Below is a mwe. Its very close to working, but I can’t figure it out. using ForwardDiff using LinearAlgebra struct Stack M::Matrix{Int} …

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## [Reduce allocations in @distributed for](https://discourse.julialang.org/t/reduce-allocations-in-distributed-for/26819)

<div class="topic-metadata">

**Author:** [@xzackli](https://discourse.julialang.org/u/xzackli)\
**Replies:** 1\
**Last updated:** [July 26, 2019, 3:29am UTC](https://discourse.julialang.org/t/reduce-allocations-in-distributed-for/26819 "2019-07-26T03:29:44Z")

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I’m doing some cheap operations on a set of huge SharedArrays, i.e. computing the distance from x,y,z. using Distributed addprocs(40); @everywhere using SharedArrays function compute\_distance(result::SharedArray, pos::…

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## [Waveform Characterization](https://discourse.julialang.org/t/waveform-characterization/20654)

<div class="topic-metadata">

**Author:** [@bomber8013](https://discourse.julialang.org/u/bomber8013)\
**Replies:** 3\
**Last updated:** [July 25, 2019, 10:45pm UTC](https://discourse.julialang.org/t/waveform-characterization/20654 "2019-07-25T22:45:57Z")

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I am developing a library for basic waveform characterization. Linked WaveformAnalysis.jl I have a few of the functions done pretty well done in the most efficient way I can think of. I am getting hung up right now with…

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## [Tracking initial condition to optimize starting value too Diffeqflux](https://discourse.julialang.org/t/tracking-initial-condition-to-optimize-starting-value-too-diffeqflux/26596)

<div class="topic-metadata">

**Author:** [@freemint](https://discourse.julialang.org/u/freemint)\
**Replies:** 11\
**Last updated:** [July 25, 2019, 4:21pm UTC](https://discourse.julialang.org/t/tracking-initial-condition-to-optimize-starting-value-too-diffeqflux/26596 "2019-07-25T16:21:44Z")

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Hello, i am curious whether i can use existing tooling to optimize initial conditions too. So far i only got the error: \*\*MethodError: no method matching OrdinaryDiffEq.Tsit5Cache(::TrackedArray{…,Array{Float64,1}}, :…

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## [Variable reference in a function created by a macro](https://discourse.julialang.org/t/variable-reference-in-a-function-created-by-a-macro/26722)

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**Author:** [@bocc](https://discourse.julialang.org/u/bocc)\
**Replies:** 7\
**Last updated:** [July 25, 2019, 3:56pm UTC](https://discourse.julialang.org/t/variable-reference-in-a-function-created-by-a-macro/26722 "2019-07-25T15:56:31Z")

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Hello, I am trying to use IntervalConstraintProgramming & associated packages to solve a geometric feasibility problem. In order to be able to use functions in constraints, the ICP package provides a macro for function …

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## [Best practices for parallel generation of pseudo-random numbers](https://discourse.julialang.org/t/best-practices-for-parallel-generation-of-pseudo-random-numbers/26504)

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**Author:** [@non-Jedi](https://discourse.julialang.org/u/non-Jedi)\
**Replies:** 11\
**Last updated:** [July 25, 2019, 3:35pm UTC](https://discourse.julialang.org/t/best-practices-for-parallel-generation-of-pseudo-random-numbers/26504 "2019-07-25T15:35:08Z")

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I’m relatively new to the world of simulation and am running some discrete event simulations using SimJulia.jl and Distributions.jl for a graduate-level class. I noticed that the Wikipedia article for Mersenne Twister (w…

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## [DynamicHMC API rewrite](https://discourse.julialang.org/t/dynamichmc-api-rewrite/18980)

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**Author:** [@Tamas\_Papp](https://discourse.julialang.org/u/Tamas_Papp)\
**Replies:** 1\
**Last updated:** [July 25, 2019, 9:02am UTC](https://discourse.julialang.org/t/dynamichmc-api-rewrite/18980 "2019-07-25T09:02:01Z")

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I will be rewriting the API of DynamicHMC.jl shortly. I started a discussion at https://github.com/tpapp/DynamicHMC.jl/issues/30 and invite users to participate there, or in this topic. In particular, if there is a fea…

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## [Formulate my own objective function using PowerModels.jl variables](https://discourse.julialang.org/t/formulate-my-own-objective-function-using-powermodels-jl-variables/25938)

<div class="topic-metadata">

**Author:** [@faoh](https://discourse.julialang.org/u/faoh)\
**Replies:** 10\
**Last updated:** [July 23, 2019, 4:23pm UTC](https://discourse.julialang.org/t/formulate-my-own-objective-function-using-powermodels-jl-variables/25938 "2019-07-23T16:23:47Z")

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Hello, I want to use PowerModels.jl flow variables to formulate a different objective function. I try to see the format of variable\_branch\_flow and call it with PowerModels.variable\_branch\_flow(pm). However, when I try…

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## [Using RCall, R 3.5.3 -\> R 3.6.1](https://discourse.julialang.org/t/using-rcall-r-3-5-3-r-3-6-1/26675)

<div class="topic-metadata">

**Author:** [@Gunter\_Faes](https://discourse.julialang.org/u/Gunter_Faes)\
**Replies:** 1\
**Last updated:** [July 23, 2019, 10:08am UTC](https://discourse.julialang.org/t/using-rcall-r-3-5-3-r-3-6-1/26675 "2019-07-23T10:08:12Z")

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First of all, this is just a field report! With R version 3.6.0, some major changes and enhancements have been implemented compared to the previous versions (e.g. R 3.5.3). This means that it became necessary to instal…

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## [PGFPlotsX howto annotate?](https://discourse.julialang.org/t/pgfplotsx-howto-annotate/26246)

<div class="topic-metadata">

**Author:** [@Rob\_van\_Weelderen](https://discourse.julialang.org/u/Rob_van_Weelderen)\
**Replies:** 7\
**Last updated:** [July 23, 2019, 8:39am UTC](https://discourse.julialang.org/t/pgfplotsx-howto-annotate/26246 "2019-07-23T08:39:24Z")

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Hello, I’m moving to using PGFPlotsX, for it’s suitability for producing good publication ready plots, and got following the PGFPlotsX.jl and PGFPlots documentation most that I need functioning. However I got stuck in …

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## [Looped optimization model](https://discourse.julialang.org/t/looped-optimization-model/26600)

<div class="topic-metadata">

**Author:** [@MuadhF](https://discourse.julialang.org/u/MuadhF)\
**Replies:** 4\
**Last updated:** [July 23, 2019, 5:19am UTC](https://discourse.julialang.org/t/looped-optimization-model/26600 "2019-07-23T05:19:15Z")

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Hi, I created a JuMP optimization model that reads input from CSV files. However, I want the program to go through more than one set of input files, so that I would have the objective values and solutions to all the mod…

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## [Decrease in performance using Threads.@threads in Linux](https://discourse.julialang.org/t/decrease-in-performance-using-threads-threads-in-linux/26522)

<div class="topic-metadata">

**Author:** [@amcostant](https://discourse.julialang.org/u/amcostant)\
**Replies:** 16\
**Last updated:** [July 23, 2019, 5:19am UTC](https://discourse.julialang.org/t/decrease-in-performance-using-threads-threads-in-linux/26522 "2019-07-23T05:19:09Z")

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I am attempting to parallelize this code function pdiff(b1::Array{Basic,1}, b2::Basic) dfdx = Array{Basic}(undef,length(b1)) Threads.@threads for i = 1:length(b1) a = Basic() ret = ccall((:basic\_…

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## [How to derive the dual formulation with JuMP?](https://discourse.julialang.org/t/how-to-derive-the-dual-formulation-with-jump/26639)

<div class="topic-metadata">

**Author:** [@dourouc05](https://discourse.julialang.org/u/dourouc05)\
**Replies:** 6\
**Last updated:** [July 23, 2019, 2:17am UTC](https://discourse.julialang.org/t/how-to-derive-the-dual-formulation-with-jump/26639 "2019-07-23T02:17:07Z")

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Hi all, The dual formulation is useful for many things (robust reformulation, column generation, and so many others). Is there a way in JuMP to generate the dual of a model? (Not getting the dual values for each constra…

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## [Is the following code using some regression technique?](https://discourse.julialang.org/t/is-the-following-code-using-some-regression-technique/26636)

<div class="topic-metadata">

**Author:** [@bsnyh](https://discourse.julialang.org/u/bsnyh)\
**Replies:** 1\
**Last updated:** [July 22, 2019, 3:57pm UTC](https://discourse.julialang.org/t/is-the-following-code-using-some-regression-technique/26636 "2019-07-22T15:57:32Z")

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The following piece of code is from the OpenStreetMapX package. The logic is pretty straightforward to follow. I was just wondering, where is the constant 3.6 from? Does it come from some statistical fittings? Any commen…

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## [Julia and Demography](https://discourse.julialang.org/t/julia-and-demography/23773)

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**Author:** [@sbacelar](https://discourse.julialang.org/u/sbacelar)\
**Replies:** 9\
**Last updated:** [July 22, 2019, 7:16am UTC](https://discourse.julialang.org/t/julia-and-demography/23773 "2019-07-22T07:16:54Z")

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Is there any work on (computational) demography using Julia?

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## [Parameter tuning in neural ODE](https://discourse.julialang.org/t/parameter-tuning-in-neural-ode/26450)

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**Author:** [@JunichiFukui](https://discourse.julialang.org/u/JunichiFukui)\
**Replies:** 15\
**Last updated:** [July 21, 2019, 10:03pm UTC](https://discourse.julialang.org/t/parameter-tuning-in-neural-ode/26450 "2019-07-21T22:03:10Z")

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Hello, I’m trying to reproduce chemical reaction equations using neural ODE system. I calculated time-series of mass fraction of chemical species and temperature using other ODE solver, and exported the solution data to…

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## [DiffEqFlux with time as additional input to Neural ODE](https://discourse.julialang.org/t/diffeqflux-with-time-as-additional-input-to-neural-ode/26456)

<div class="topic-metadata">

**Author:** [@Michael\_Struwig](https://discourse.julialang.org/u/Michael_Struwig)\
**Replies:** 7\
**Last updated:** [July 21, 2019, 3:41pm UTC](https://discourse.julialang.org/t/diffeqflux-with-time-as-additional-input-to-neural-ode/26456 "2019-07-21T15:41:17Z")

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Hi! My academic or theoretical vocabulary isn’t extensive, so please excuse any lack of terminology on my part. Please point the correct terminology out to me, I’m more than happy to learn. I’ve been enjoying and follo…

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## [How to feed initial solution to solver?](https://discourse.julialang.org/t/how-to-feed-initial-solution-to-solver/26577)

<div class="topic-metadata">

**Author:** [@Qun](https://discourse.julialang.org/u/Qun)\
**Replies:** 2\
**Last updated:** [July 21, 2019, 12:08pm UTC](https://discourse.julialang.org/t/how-to-feed-initial-solution-to-solver/26577 "2019-07-21T12:08:20Z")

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I am keen to learn how to feed an initial solution to a solver. I use the following example and I got the above warning when I used CPLEX, Cbc, Gurobi, GLPK. Could any one point me in the right direction to solve this is…

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## [@async calls to WebSockets read and write methods](https://discourse.julialang.org/t/async-calls-to-websockets-read-and-write-methods/26405)

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**Author:** [@Jasha10](https://discourse.julialang.org/u/Jasha10)\
**Replies:** 6\
**Last updated:** [July 20, 2019, 8:09pm UTC](https://discourse.julialang.org/t/async-calls-to-websockets-read-and-write-methods/26405 "2019-07-20T20:09:22Z")

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I’ve put together a simple coroutine that makes use of the WebSockets.jl package, but I’m not sure if WebSockets.jl (or the underlying HTTP.jl) is designed to be able to handle this sort of asynchronous behavior: using …

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## [How to correctly handle batches in this model](https://discourse.julialang.org/t/how-to-correctly-handle-batches-in-this-model/26570)

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**Author:** [@danipozo](https://discourse.julialang.org/u/danipozo)\
**Replies:** 0\
**Last updated:** [July 20, 2019, 12:03am UTC](https://discourse.julialang.org/t/how-to-correctly-handle-batches-in-this-model/26570 "2019-07-20T00:03:09Z")

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I’m trying to write a model similar to the one in Image to markup with coarse to fine attention, where a fully convolutional network is first applied to an image (resulting in a smaller image with a greater number of cha…

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## [Multi-Objective Optimization Support](https://discourse.julialang.org/t/multi-objective-optimization-support/16731)

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**Author:** [@PastelBelem8](https://discourse.julialang.org/u/PastelBelem8)\
**Replies:** 3\
**Last updated:** [July 19, 2019, 7:09pm UTC](https://discourse.julialang.org/t/multi-objective-optimization-support/16731 "2019-07-19T19:09:19Z")

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I’m working on my master thesis on Multi-Objective Optimization (MOO) and I found JuMP to be a clean and elegant framework. However, JuMP does not currently support Multi-Objective optimization. Are you planning to suppo…

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## [Interact + Mux: how to get independent connections?](https://discourse.julialang.org/t/interact-mux-how-to-get-independent-connections/26538)

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**Author:** [@sylvaticus](https://discourse.julialang.org/u/sylvaticus)\
**Replies:** 2\
**Last updated:** [July 19, 2019, 12:05pm UTC](https://discourse.julialang.org/t/interact-mux-how-to-get-independent-connections/26538 "2019-07-19T12:05:56Z")

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Hello, I am trying to get a model whose controls and results are exposed on the web (for now on my own development machine). I did manage to get a dummy model working, but I noticed that different connections are not in…

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## [Trouble displaying an image using ImageView.imshow()](https://discourse.julialang.org/t/trouble-displaying-an-image-using-imageview-imshow/26493)

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**Author:** [@Didier\_Chatenay](https://discourse.julialang.org/u/Didier_Chatenay)\
**Replies:** 11\
**Last updated:** [July 19, 2019, 9:28am UTC](https://discourse.julialang.org/t/trouble-displaying-an-image-using-imageview-imshow/26493 "2019-07-19T09:28:21Z")

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I am using Julia with Atom on a MacBook Pro When I try to display an image like in the following few lines at the REPL using Images, ImageView, TestImages img = testimage(“mandrill”) ImageView.imshow(img) a window a…

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## [Julia multiprocessing is not using fork in Linux?](https://discourse.julialang.org/t/julia-multiprocessing-is-not-using-fork-in-linux/26513)

<div class="topic-metadata">

**Author:** [@jwu](https://discourse.julialang.org/u/jwu)\
**Replies:** 2\
**Last updated:** [July 19, 2019, 1:39am UTC](https://discourse.julialang.org/t/julia-multiprocessing-is-not-using-fork-in-linux/26513 "2019-07-19T01:39:45Z")

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I am not sure I understand it correctly or not. In python multiprocessing, it is using fork in Linux, so the children processes shares memory directly. The memory sharing will not change if you are not changing it since …

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## [Create PDF document with PGFPlotsX figures, captions, a table, and some text](https://discourse.julialang.org/t/create-pdf-document-with-pgfplotsx-figures-captions-a-table-and-some-text/26478)

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**Author:** [@yakir12](https://discourse.julialang.org/u/yakir12)\
**Replies:** 22\
**Last updated:** [July 18, 2019, 6:56pm UTC](https://discourse.julialang.org/t/create-pdf-document-with-pgfplotsx-figures-captions-a-table-and-some-text/26478 "2019-07-18T18:56:05Z")

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I’m using PGFPlotsX to create my figures, but I want to bundle them in a report with some metadata that comes with those figures (mostly some mean-error estimates in a table and comments in a paragraph of text). I want t…

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## [Dask and Dask-cuDF Julia alternative?](https://discourse.julialang.org/t/dask-and-dask-cudf-julia-alternative/26446)

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**Author:** [@ldsands](https://discourse.julialang.org/u/ldsands)\
**Replies:** 8\
**Last updated:** [July 18, 2019, 3:03pm UTC](https://discourse.julialang.org/t/dask-and-dask-cudf-julia-alternative/26446 "2019-07-18T15:03:04Z")

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Hello everyone, TLDR: looking for information on Julia’s Dask and Dask-cuDF alternatives I’m having to analyze some data for my social science degree and it is very large. I’m using python, pandas and dask to parrellel…

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## [Chaostools tangent\_integrator stiff solvers](https://discourse.julialang.org/t/chaostools-tangent-integrator-stiff-solvers/26464)

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**Author:** [@jamblejoe](https://discourse.julialang.org/u/jamblejoe)\
**Replies:** 27\
**Last updated:** [July 18, 2019, 1:21pm UTC](https://discourse.julialang.org/t/chaostools-tangent-integrator-stiff-solvers/26464 "2019-07-18T13:21:34Z")

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Hi, I want to use the tangent\_integrator function from the ChaosTools package with solvers for stiff problems: integ = tangent\_integrator(cds, w0; alg=Rodas5(), abstol=1e-9, reltol=1e-9) step!(integ, 1.0) but this giv…

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## [Help me structure my code and extend it to a working example: Using DiffEqFlux to interpolate GDP data and see if there is a singularity](https://discourse.julialang.org/t/help-me-structure-my-code-and-extend-it-to-a-working-example-using-diffeqflux-to-interpolate-gdp-data-and-see-if-there-is-a-singularity/26487)

<div class="topic-metadata">

**Author:** [@freemint](https://discourse.julialang.org/u/freemint)\
**Replies:** 2\
**Last updated:** [July 18, 2019, 11:52am UTC](https://discourse.julialang.org/t/help-me-structure-my-code-and-extend-it-to-a-working-example-using-diffeqflux-to-interpolate-gdp-data-and-see-if-there-is-a-singularity/26487 "2019-07-18T11:52:46Z")

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Hello, i tried to solve my own toy problem for DiffEqFlux since i found the example that comes with DiffEqFlux confusing. The source is available here, frankly it is in a messy shape right now: GitHub - freemin7/GDPPr-…

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## [CSP examples in Julia?](https://discourse.julialang.org/t/csp-examples-in-julia/20011)

<div class="topic-metadata">

**Author:** [@NHDaly](https://discourse.julialang.org/u/NHDaly)\
**Replies:** 2\
**Last updated:** [July 18, 2019, 12:13am UTC](https://discourse.julialang.org/t/csp-examples-in-julia/20011 "2019-07-18T00:13:57Z")

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Golang’s concurrency primitives were originally inspired by C. A. R. Hoare’s famous 1978 paper “Communicating sequential processes”, (paper, book). Here’s a blog post where they talk about it: This git repo re-implem…

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## [Can I get variable value during the optimization JuMP.value?](https://discourse.julialang.org/t/can-i-get-variable-value-during-the-optimization-jump-value/26474)

<div class="topic-metadata">

**Author:** [@faoh](https://discourse.julialang.org/u/faoh)\
**Replies:** 2\
**Last updated:** [July 17, 2019, 6:50pm UTC](https://discourse.julialang.org/t/can-i-get-variable-value-during-the-optimization-jump-value/26474 "2019-07-17T18:50:55Z")

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I want to get variables’ value and use it in objective function during the optimization. When I try JuMP.value(), it shows NoOptimizer(). But the Optimizer is defined in the main function. Is there anyway that I can ge…

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