# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=520

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**Page:** 521

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## [ImageView update image](https://discourse.julialang.org/t/imageview-update-image/16737)

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**Author:** [@harven](https://discourse.julialang.org/u/harven)\
**Replies:** 3\
**Last updated:** [October 25, 2018, 7:39pm UTC](https://discourse.julialang.org/t/imageview-update-image/16737 "2018-10-25T19:39:50Z")

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I have an img that I display using ImageView.imshow(img). When img is modified, I would like to tell imshow to update the image. A thread on discourse suggest to call again imshow as follows. canvas = imshow(img)\[“gui”…

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## [Error when I run for the first time my parallel code](https://discourse.julialang.org/t/error-when-i-run-for-the-first-time-my-parallel-code/16435)

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**Author:** [@dsHitman](https://discourse.julialang.org/u/dsHitman)\
**Replies:** 1\
**Last updated:** [October 25, 2018, 7:32pm UTC](https://discourse.julialang.org/t/error-when-i-run-for-the-first-time-my-parallel-code/16435 "2018-10-25T19:32:35Z")

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Hi, when I run for the first time my parallel code the REPL give me this error \`ERROR: LoadError: On worker 2: UndefVarError: SharedArray not defined top-level scope at none:0 eval at .\\boot.jl:319 #116 at C:\\cygwin…

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## [Benchmarking ways to write/load DataFrames IndexedTables to disk](https://discourse.julialang.org/t/benchmarking-ways-to-write-load-dataframes-indexedtables-to-disk/8973)

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**Author:** [@xiaodai](https://discourse.julialang.org/u/xiaodai)\
**Replies:** 42\
**Last updated:** [October 25, 2018, 3:55pm UTC](https://discourse.julialang.org/t/benchmarking-ways-to-write-load-dataframes-indexedtables-to-disk/8973 "2018-10-25T15:55:16Z")

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Update 2018-Feb-19: added R feather and Pandas; thanks to @zhangliye for the pandas code For Julia, JLD.jl has the fastest write-solution and I have used it via the ultra-convenient FileIO.jl. However for interop with …

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## [Multivariate Normal with Positive Semi-Definite Covariance Matrix](https://discourse.julialang.org/t/multivariate-normal-with-positive-semi-definite-covariance-matrix/3029)

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**Author:** [@jacobcvt12](https://discourse.julialang.org/u/jacobcvt12)\
**Replies:** 19\
**Last updated:** [October 25, 2018, 3:35pm UTC](https://discourse.julialang.org/t/multivariate-normal-with-positive-semi-definite-covariance-matrix/3029 "2018-10-25T15:35:55Z")

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Hi All, I’m using julia to sample from a gaussian process with squared exponential kernel. using Distributions, Distances x\_star = -5:0.1:5 K = exp(-0.5 \* pairwise(SqEuclidean(), x\_star')) f\_star = rand(MvNormal(K), 1…

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## [Is there any plan for GPU linear algebra?](https://discourse.julialang.org/t/is-there-any-plan-for-gpu-linear-algebra/16766)

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**Author:** [@Roger-luo](https://discourse.julialang.org/u/Roger-luo)\
**Replies:** 3\
**Last updated:** [October 25, 2018, 9:11am UTC](https://discourse.julialang.org/t/is-there-any-plan-for-gpu-linear-algebra/16766 "2018-10-25T09:11:02Z")

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I was trying to transfer from PyTorch, however, we don’t have a magma wrapper at the moment, do we? So is there anything includes things like SVD on GPU? And is there any plan (or anyone interested in this) to make a wr…

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## [Setting gravity in RigidBodyDynamics.jl](https://discourse.julialang.org/t/setting-gravity-in-rigidbodydynamics-jl/16748)

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**Author:** [@HiroIshida](https://discourse.julialang.org/u/HiroIshida)\
**Replies:** 2\
**Last updated:** [October 25, 2018, 6:30am UTC](https://discourse.julialang.org/t/setting-gravity-in-rigidbodydynamics-jl/16748 "2018-10-25T06:30:59Z")

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I have just started to use RigidBodyDynamics. According to the tutorial, the proper way to set gravity seems m = Mechanism(world; gravity = SVector(0, 0, g). But when constructing a mechanism using parse\_urdf, what is t…

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## [Jacchia-Roberts 1971 Atmospheric model is now available in SatelliteToolbox.jl](https://discourse.julialang.org/t/jacchia-roberts-1971-atmospheric-model-is-now-available-in-satellitetoolbox-jl/16758)

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**Author:** [@Ronis\_BR](https://discourse.julialang.org/u/Ronis_BR)\
**Replies:** 0\
**Last updated:** [October 24, 2018, 8:06pm UTC](https://discourse.julialang.org/t/jacchia-roberts-1971-atmospheric-model-is-now-available-in-satellitetoolbox-jl/16758 "2018-10-24T20:06:36Z")

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Hi guys! I just want to let you know that we now have a native implementation of The Jacchia-Roberts 1971 atmospheric model in SatelliteToolbox.jl. You just need to use master because I still need to do somethings befor…

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## [Jupyter: not work PlotlyJS, Gadfly, and GR displays only byte code](https://discourse.julialang.org/t/jupyter-not-work-plotlyjs-gadfly-and-gr-displays-only-byte-code/16747)

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**Author:** [@YermolenkoIgor](https://discourse.julialang.org/u/YermolenkoIgor)\
**Replies:** 0\
**Last updated:** [October 24, 2018, 4:32pm UTC](https://discourse.julialang.org/t/jupyter-not-work-plotlyjs-gadfly-and-gr-displays-only-byte-code/16747 "2018-10-24T16:32:57Z")

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using Plots gr(html\_output\_format=:png) plot(1:2,1:2) base64 binary data: b3BlbjogTm8gc3VjaCBmaWxlIG9yIGRpcmVjdG9yeQpvcGVuOiBObyBzdWNoIGZpbGUgb3IgZGlyZWN0b3J5CkdLUzogZmlsZSBvcGVuIGVycm9yIChDOlxVc2Vyc1yIo67g7FwuanVsaWFcc…

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## [ccall, C pointers and Multi-Core ](https://discourse.julialang.org/t/ccall-c-pointers-and-multi-core/16733)

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**Author:** [@mischmi](https://discourse.julialang.org/u/mischmi)\
**Replies:** 1\
**Last updated:** [October 24, 2018, 4:32pm UTC](https://discourse.julialang.org/t/ccall-c-pointers-and-multi-core/16733 "2018-10-24T16:32:55Z")

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Hello, I’m having a bit of trouble with parallelization and a C library. I’ll try to describe the issue as best as possible: I have a certain mutable struct that stores pointers to memory allocated by C through a ccall…

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## [Updating options in Ipopt](https://discourse.julialang.org/t/updating-options-in-ipopt/16013)

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**Author:** [@Wikunia](https://discourse.julialang.org/u/Wikunia)\
**Replies:** 4\
**Last updated:** [October 24, 2018, 8:40am UTC](https://discourse.julialang.org/t/updating-options-in-ipopt/16013 "2018-10-24T08:40:17Z")

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Is it possible to easily update the options used in Ipopt? Trying to change the value of mu using the :mu\_init option but it seems that Ipopt uses an immutable struct so I don’t have access. I used it in Julia v0.6 and …

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## [Deep Reinforcement Learning Example that will build on Julia 1.0.1?](https://discourse.julialang.org/t/deep-reinforcement-learning-example-that-will-build-on-julia-1-0-1/16656)

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**Author:** [@Jack\_Vice](https://discourse.julialang.org/u/Jack_Vice)\
**Replies:** 6\
**Last updated:** [October 23, 2018, 10:17pm UTC](https://discourse.julialang.org/t/deep-reinforcement-learning-example-that-will-build-on-julia-1-0-1/16656 "2018-10-23T22:17:54Z")

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Hi, Can someone recommend a good Deep Reinforcement Learning example code that will build on Julia 1.0.1. I am looking for Actor-Critic, policy gradient or even deep q learning example that works so I can then start doin…

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## [Producer/Consumer Tasks Do Not End Properly](https://discourse.julialang.org/t/producer-consumer-tasks-do-not-end-properly/16645)

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**Author:** [@zekeriya.sari](https://discourse.julialang.org/u/zekeriya.sari)\
**Replies:** 2\
**Last updated:** [October 23, 2018, 7:15pm UTC](https://discourse.julialang.org/t/producer-consumer-tasks-do-not-end-properly/16645 "2018-10-23T19:15:28Z")

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I want to construct an unbuffered channel and bind a producer task feeding the channel for some certain amount of data and a consumer task consuming the produced data in in infinite loop until a poission pill is taken. T…

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## ["using Plots" suddenly stopped working](https://discourse.julialang.org/t/using-plots-suddenly-stopped-working/16695)

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**Author:** [@Torkel](https://discourse.julialang.org/u/Torkel)\
**Replies:** 2\
**Last updated:** [October 23, 2018, 4:47pm UTC](https://discourse.julialang.org/t/using-plots-suddenly-stopped-working/16695 "2018-10-23T16:47:42Z")

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I have been using Plots in Julia 1.0 for a whil now and it all worked ok. However, I needed some plots were I more easily could customize various things (line thickness etc.) to make a pretty figure and I thought I shoul…

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## [ImageView: display to true resolution](https://discourse.julialang.org/t/imageview-display-to-true-resolution/16646)

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**Author:** [@harven](https://discourse.julialang.org/u/harven)\
**Replies:** 3\
**Last updated:** [October 23, 2018, 2:27pm UTC](https://discourse.julialang.org/t/imageview-display-to-true-resolution/16646 "2018-10-23T14:27:19Z")

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I am using julia v1.0.1 with ImageView v0.8. If I use imshow(image) with an image given by a 1000x1000 array, the image is displayed in a 1000x1000 window. Unfortunately, the image is scaled down in order to leave a ma…

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## [How to get the Solution Pool using Julia/CPLEX?](https://discourse.julialang.org/t/how-to-get-the-solution-pool-using-julia-cplex/16684)

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**Author:** [@Giovanna\_Abreu](https://discourse.julialang.org/u/Giovanna_Abreu)\
**Replies:** 0\
**Last updated:** [October 23, 2018, 2:25pm UTC](https://discourse.julialang.org/t/how-to-get-the-solution-pool-using-julia-cplex/16684 "2018-10-23T14:25:39Z")

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Hi everyone, I need the solution pool for storing multiple solutions of a MIP model. I using Julia and the packages JuMP and CPLEX as a solver. So I need to collect solutions within a given percentage of the optimal sol…

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## [\[ANN\] Schemata.jl ready on Julia 1.0](https://discourse.julialang.org/t/ann-schemata-jl-ready-on-julia-1-0/16675)

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**Author:** [@jocklawrie](https://discourse.julialang.org/u/jocklawrie)\
**Replies:** 0\
**Last updated:** [October 23, 2018, 10:41am UTC](https://discourse.julialang.org/t/ann-schemata-jl-ready-on-julia-1-0/16675 "2018-10-23T10:41:27Z")

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Hi all, After an alpha release last November, Schemata.jl is finally ready for 1.0. From the README: A Schema is a specification of a data set. It exists independently of any particular data set, and therefore can b…

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## [ControlSystems & LTI structure?](https://discourse.julialang.org/t/controlsystems-lti-structure/16653)

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**Author:** [@BLI](https://discourse.julialang.org/u/BLI)\
**Replies:** 2\
**Last updated:** [October 23, 2018, 6:46am UTC](https://discourse.julialang.org/t/controlsystems-lti-structure/16653 "2018-10-23T06:46:22Z")

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I haven’t delved deeply into Julia types/structs, and am curious about the LTI structure… It appears to me that LTI is defined for finite dimensional systems only, i.e., no time delay, etc. What is the internal storage…

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## [How to achieve atomic global variables with multiple processes (not threads)?](https://discourse.julialang.org/t/how-to-achieve-atomic-global-variables-with-multiple-processes-not-threads/16626)

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**Author:** [@novoselrok](https://discourse.julialang.org/u/novoselrok)\
**Replies:** 2\
**Last updated:** [October 22, 2018, 2:57pm UTC](https://discourse.julialang.org/t/how-to-achieve-atomic-global-variables-with-multiple-processes-not-threads/16626 "2018-10-22T14:57:04Z")

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Hello. I’m writing a dynamically scheduled parallel algorithm, which spawns new processes when other processes run out of work. I’m keeping a counter of currently running processes so I don’t spawn more than max availab…

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## [\[Solved\]Flux.jl: can it be used to train networks with multiple distinct inputs?](https://discourse.julialang.org/t/solved-flux-jl-can-it-be-used-to-train-networks-with-multiple-distinct-inputs/16498)

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**Author:** [@thvhauwe](https://discourse.julialang.org/u/thvhauwe)\
**Replies:** 1\
**Last updated:** [October 22, 2018, 2:57pm UTC](https://discourse.julialang.org/t/solved-flux-jl-can-it-be-used-to-train-networks-with-multiple-distinct-inputs/16498 "2018-10-22T14:57:02Z")

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Similar network in Keras: The Functional API I’m getting errors when running the following basic example code trying to train a network with two inputs and 1 output. The network is made up out of a left branch and a rig…

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## [ReverseDiffSparse Deprecation Warnings Julia 0.7 (JuMP)](https://discourse.julialang.org/t/reversediffsparse-deprecation-warnings-julia-0-7-jump/16611)

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**Author:** [@rhuffman](https://discourse.julialang.org/u/rhuffman)\
**Replies:** 1\
**Last updated:** [October 21, 2018, 9:34pm UTC](https://discourse.julialang.org/t/reversediffsparse-deprecation-warnings-julia-0-7-jump/16611 "2018-10-21T21:34:31Z")

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I’m working to update my code from Julia 0.6.3 to 0.7/1.0, and I’m running into an issue with ReverseDiffSparse.jl. I do not directly use this module, but my code does use JuMP and Ipopt. It appears that ReverseDiffSpar…

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## [ML demo code](https://discourse.julialang.org/t/ml-demo-code/16547)

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**Author:** [@microlifecc](https://discourse.julialang.org/u/microlifecc)\
**Replies:** 9\
**Last updated:** [October 21, 2018, 7:09pm UTC](https://discourse.julialang.org/t/ml-demo-code/16547 "2018-10-21T19:09:21Z")

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I am new to Machine Learning in Julia and am going through the tutorial here. The code for the tutorial is here. While trying to run the following line I am getting an error: Metalhead.imagenet\_classes\[rand(1:1000,1,1)…

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## [Why does the function "gif" take forever to run?](https://discourse.julialang.org/t/why-does-the-function-gif-take-forever-to-run/16595)

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**Author:** [@Zhenghao](https://discourse.julialang.org/u/Zhenghao)\
**Replies:** 0\
**Last updated:** [October 21, 2018, 7:53am UTC](https://discourse.julialang.org/t/why-does-the-function-gif-take-forever-to-run/16595 "2018-10-21T07:53:47Z")

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I’m trying to use “@animate” and “gif” in Plots.jl to generate .gif file. The macro @animate can be operated successfully, while the function “gif” cannot stop running and no gif file is generated. I have installed FFmpe…

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## [error compiling \_plot!: error compiling \_display: could not load library "libGR.dll" The specified module could not be found.](https://discourse.julialang.org/t/error-compiling-plot-error-compiling-display-could-not-load-library-libgr-dll-the-specified-module-could-not-be-found/15965)

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**Author:** [@Vince](https://discourse.julialang.org/u/Vince)\
**Replies:** 2\
**Last updated:** [October 21, 2018, 6:31am UTC](https://discourse.julialang.org/t/error-compiling-plot-error-compiling-display-could-not-load-library-libgr-dll-the-specified-module-could-not-be-found/15965 "2018-10-21T06:31:33Z")

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I am completely new to programming and Julia is my first language to learn. I am using Atom IDE for Julia whenever i try to plot anything like using Plots; plot(rand(5)) the above error is displayed. I tried using ENV\[…

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## [Macro for generating @NLconstraint](https://discourse.julialang.org/t/macro-for-generating-nlconstraint/16535)

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**Author:** [@chkwon](https://discourse.julialang.org/u/chkwon)\
**Replies:** 3\
**Last updated:** [October 20, 2018, 10:27pm UTC](https://discourse.julialang.org/t/macro-for-generating-nlconstraint/16535 "2018-10-20T22:27:55Z")

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On julia v0.7 and JuMP v0.18: using JuMP macro zero\_constraint(m, expr) quote @NLconstraint($(esc(m)), $(esc(expr)) == 0) end end m = Model() @variable(m, x) @variable(m, y) @zero\_constraint(m, x) …

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## [Material for Tax Benefit Models](https://discourse.julialang.org/t/material-for-tax-benefit-models/16501)

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**Author:** [@grahamstark](https://discourse.julialang.org/u/grahamstark)\
**Replies:** 0\
**Last updated:** [October 18, 2018, 5:38pm UTC](https://discourse.julialang.org/t/material-for-tax-benefit-models/16501 "2018-10-18T17:38:54Z")

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Hi, first time posting here. Hello everyone. I write microsimulation models for a living - more here, if you’re interested - and I’m starting work on an open-source Tax-Benefit model for Scotland. This is unfunded at p…

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## [Build NLexpression in steps](https://discourse.julialang.org/t/build-nlexpression-in-steps/15199)

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**Author:** [@jacob-roth](https://discourse.julialang.org/u/jacob-roth)\
**Replies:** 1\
**Last updated:** [October 19, 2018, 5:12pm UTC](https://discourse.julialang.org/t/build-nlexpression-in-steps/15199 "2018-10-19T17:12:50Z")

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I want to build an NLexpression which is the sum of elements of an array containing both JuMP variables and Float64s, something like: model = Model() @variable(model, x\[1:2\]) xx = \[x\[1\]; 3.0; 4.0; 5.0; x\[2\]\] @NLexpressi…

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## [Continued development of GSL.jl](https://discourse.julialang.org/t/continued-development-of-gsl-jl/16131)

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**Author:** [@ludvigak](https://discourse.julialang.org/u/ludvigak)\
**Replies:** 10\
**Last updated:** [October 19, 2018, 4:47pm UTC](https://discourse.julialang.org/t/continued-development-of-gsl-jl/16131 "2018-10-19T16:47:48Z")

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I would like to check if anybody knows what the status is of the GSL package, and what the community interest is for continued development. Currently there has not been any development in a while, things are not working…

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## [@expression instead of constraints](https://discourse.julialang.org/t/expression-instead-of-constraints/16508)

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**Author:** [@Rasoul](https://discourse.julialang.org/u/Rasoul)\
**Replies:** 7\
**Last updated:** [October 19, 2018, 4:12pm UTC](https://discourse.julialang.org/t/expression-instead-of-constraints/16508 "2018-10-19T16:12:50Z")

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I have two trigonometric variables (i.e., cs\_fr and si\_fr) in my code and at the same time, there are two trigonometric terms (i.e., cs\_to and si\_to) which linearly depend on cs\_fr and si\_fr. I have defined cs\_fr and si\_…

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## [Data approximation with a curve](https://discourse.julialang.org/t/data-approximation-with-a-curve/16124)

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**Author:** [@Andrey.Borzunov](https://discourse.julialang.org/u/Andrey.Borzunov)\
**Replies:** 18\
**Last updated:** [October 18, 2018, 10:38pm UTC](https://discourse.julialang.org/t/data-approximation-with-a-curve/16124 "2018-10-18T22:38:13Z")

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I have a dataset with 130k points. I want to approximate them with some polynomial p(not more than 11th degree for example), so that later i could call y = p(x) for x \\in \[-90.,90\] to get approximated value. Cubic spline…

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## [DifferentialEquations.jl + Flux.jl or Knet.jl](https://discourse.julialang.org/t/differentialequations-jl-flux-jl-or-knet-jl/8208)

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**Author:** [@nbren12](https://discourse.julialang.org/u/nbren12)\
**Replies:** 15\
**Last updated:** [October 18, 2018, 2:50pm UTC](https://discourse.julialang.org/t/differentialequations-jl-flux-jl-or-knet-jl/8208 "2018-10-18T14:50:54Z")

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I am trying to estimate various dynamical systems using neural network models. I am very interested in using the integrators provided by DifferentialEquations.jl to do this, and the docs for that package even have nice e…

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