# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?page=515

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**Page:** 516

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## [Flux gradient clipping](https://discourse.julialang.org/t/flux-gradient-clipping/18544)

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**Author:** [@Fart](https://discourse.julialang.org/u/Fart)\
**Replies:** 2\
**Last updated:** [December 11, 2018, 7:21pm UTC](https://discourse.julialang.org/t/flux-gradient-clipping/18544 "2018-12-11T19:21:04Z")

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Does anyone have a working implementation of gradient clipping in Flux? I’ve tried directly modifying the param.grad field but get LoadError: type TrackedArray is immutable

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## [How to use CachingPool?](https://discourse.julialang.org/t/how-to-use-cachingpool/18498)

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**Author:** [@MaximilianJHuber](https://discourse.julialang.org/u/MaximilianJHuber)\
**Replies:** 4\
**Last updated:** [December 10, 2018, 11:55pm UTC](https://discourse.julialang.org/t/how-to-use-cachingpool/18498 "2018-12-10T23:55:19Z")

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Do I used the CachingPool incorrectly, or is this a bug? On Julia 1.0.2: using Distributed addprocs(2) @everywhere f\_passall(a,x) = length(x) + a its = 1:20 bigarr = ones(10^8) pool = CachingPool(workers()) pmap(pool, …

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## [Performance of log in nonlinear optimization](https://discourse.julialang.org/t/performance-of-log-in-nonlinear-optimization/18450)

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**Author:** [@danielcas](https://discourse.julialang.org/u/danielcas)\
**Replies:** 6\
**Last updated:** [December 10, 2018, 9:30pm UTC](https://discourse.julialang.org/t/performance-of-log-in-nonlinear-optimization/18450 "2018-12-10T21:30:06Z")

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I’m having some trouble with the function “log” in an optimization problem. For instance: I create a variable, and then the following constraint: @NLconstraint(ModelName, log(x) \<=100), I use Ipopt to solve it (a fea…

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## [How to use FFTW MPI routines with MPI.jl](https://discourse.julialang.org/t/how-to-use-fftw-mpi-routines-with-mpi-jl/18533)

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**Author:** [@favba](https://discourse.julialang.org/u/favba)\
**Replies:** 2\
**Last updated:** [December 10, 2018, 7:33pm UTC](https://discourse.julialang.org/t/how-to-use-fftw-mpi-routines-with-mpi-jl/18533 "2018-12-10T19:33:37Z")

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I’d like to use FFTW’s distributed memory routines and I have several doubts on how to achieve this. I guess one should be able to build that on top of MPI.jl and FFTW.jl, right? I’m still stuck in very conceptual doubt…

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## [Different parametrizations of probability distributions in Distributions.jl](https://discourse.julialang.org/t/different-parametrizations-of-probability-distributions-in-distributions-jl/18435)

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**Author:** [@alejandromerchan](https://discourse.julialang.org/u/alejandromerchan)\
**Replies:** 5\
**Last updated:** [December 10, 2018, 5:23pm UTC](https://discourse.julialang.org/t/different-parametrizations-of-probability-distributions-in-distributions-jl/18435 "2018-12-10T17:23:21Z")

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In R there are several probability distributions that allow keywords for different parametrizations of the same distribution. For example, I use the Negative Binomial distribution a lot in my simulations of some biologic…

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## [JuMP and Julia 0.7/1.0](https://discourse.julialang.org/t/jump-and-julia-0-7-1-0/12964)

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**Author:** [@miles.lubin](https://discourse.julialang.org/u/miles.lubin)\
**Replies:** 15\
**Last updated:** [December 9, 2018, 6:58pm UTC](https://discourse.julialang.org/t/jump-and-julia-0-7-1-0/12964 "2018-12-09T18:58:59Z")

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Updated Oct 1: tl;dr: Thanks mostly to the persistence of @ExpandingMan, JuMP 0.18.3 was released today supporting Julia 0.6, 0.7, and 1.0. Upgrade away! If you are using JuMP 0.18 on Julia 0.6, we do recommend upgradin…

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## [Using JuMP to pick winners of a tournament](https://discourse.julialang.org/t/using-jump-to-pick-winners-of-a-tournament/18476)

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**Author:** [@tyleransom](https://discourse.julialang.org/u/tyleransom)\
**Replies:** 2\
**Last updated:** [December 9, 2018, 2:11pm UTC](https://discourse.julialang.org/t/using-jump-to-pick-winners-of-a-tournament/18476 "2018-12-09T14:11:48Z")

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Hi, I’m using JuMP to pick winners of games of a single-elimination tournament. I have everything running fine except for the fact that I can’t seem to figure out how to impose a constraint that eliminated teams not be …

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## [MIQP: How does Pavito treat convex quadratic functions?](https://discourse.julialang.org/t/miqp-how-does-pavito-treat-convex-quadratic-functions/18400)

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**Author:** [@Olegg](https://discourse.julialang.org/u/Olegg)\
**Replies:** 6\
**Last updated:** [December 8, 2018, 1:19pm UTC](https://discourse.julialang.org/t/miqp-how-does-pavito-treat-convex-quadratic-functions/18400 "2018-12-08T13:19:43Z")

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Some Integer Programming solvers, e.g. CPLEX, provide specialised algorithms for convex quadratic constraints and objectives. Does Pavito enable such algorithms for a quadratic objective, or is it treated as a general…

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## [Taking Fitting Seriously](https://discourse.julialang.org/t/taking-fitting-seriously/13281)

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**Author:** [@oxinabox](https://discourse.julialang.org/u/oxinabox)\
**Replies:** 39\
**Last updated:** [December 8, 2018, 9:58am UTC](https://discourse.julialang.org/t/taking-fitting-seriously/13281 "2018-12-08T09:58:28Z")

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I’ve been thinking about taking our fitting APIs seriously for a while now. (But am very busy so have not advanced it too far). I got to briefly talk to some people at JuliaCon about it, so I am quickly writing up som…

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## [RigidBodyDynamics URDF inertia values](https://discourse.julialang.org/t/rigidbodydynamics-urdf-inertia-values/18384)

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**Author:** [@RogerP](https://discourse.julialang.org/u/RogerP)\
**Replies:** 3\
**Last updated:** [December 8, 2018, 3:38am UTC](https://discourse.julialang.org/t/rigidbodydynamics-urdf-inertia-values/18384 "2018-12-08T03:38:42Z")

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I am building my models directly from a relational database and the RigidBody components are loaded with those inertia values. (I can simply call up different configurations of robot arm with various numbers of links/joi…

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## [RemoteChannel with priority](https://discourse.julialang.org/t/remotechannel-with-priority/18442)

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**Author:** [@JesperMartinsson](https://discourse.julialang.org/u/JesperMartinsson)\
**Replies:** 0\
**Last updated:** [December 7, 2018, 10:49pm UTC](https://discourse.julialang.org/t/remotechannel-with-priority/18442 "2018-12-07T22:49:28Z")

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Is there a preferred way to incorporate priorities into RemoteChannels so that take! will deliver the most prioritized item first?

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## [Maximum Likelihood Example Update](https://discourse.julialang.org/t/maximum-likelihood-example-update/18436)

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**Author:** [@Donald\_Lacombe](https://discourse.julialang.org/u/Donald_Lacombe)\
**Replies:** 2\
**Last updated:** [December 7, 2018, 9:36pm UTC](https://discourse.julialang.org/t/maximum-likelihood-example-update/18436 "2018-12-07T21:36:25Z")

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Hello! I wanted to point to a new gist that I have developed to update the Normal Linear Model Maximum Likelihood example that is part of the Optim.jl examples. I am going over all of my code to make sure it is 0.7.0 c…

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## [How to test missing value in CSV package?](https://discourse.julialang.org/t/how-to-test-missing-value-in-csv-package/7535)

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**Author:** [@Fred](https://discourse.julialang.org/u/Fred)\
**Replies:** 11\
**Last updated:** [December 7, 2018, 6:01pm UTC](https://discourse.julialang.org/t/how-to-test-missing-value-in-csv-package/7535 "2018-12-07T18:01:30Z")

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Hi, I try to test if there is a missing value at a specific position of a dataframe obtained with the CSV package and I did not find the function to do that. Thank you for your help. julia\> x = CSV.read("data/data.csv"…

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## [Fibonacci Heap implementation](https://discourse.julialang.org/t/fibonacci-heap-implementation/18412)

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**Author:** [@Lefteris\_Manousakis](https://discourse.julialang.org/u/Lefteris_Manousakis)\
**Replies:** 4\
**Last updated:** [December 7, 2018, 1:07pm UTC](https://discourse.julialang.org/t/fibonacci-heap-implementation/18412 "2018-12-07T13:07:20Z")

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Hi everyone! I am implementing a Local Search algorithm using the Static Move Descriptors presented in A strategy for reducing the computational complexity of local search-based methods for the vehicle routing problem - …

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## [Buglet? Warning on groupby](https://discourse.julialang.org/t/buglet-warning-on-groupby/18390)

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**Author:** [@iwelch](https://discourse.julialang.org/u/iwelch)\
**Replies:** 1\
**Last updated:** [December 6, 2018, 5:58pm UTC](https://discourse.julialang.org/t/buglet-warning-on-groupby/18390 "2018-12-06T17:58:37Z")

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Is the Warning message a buglet? julia\> using DataFrames; df= DataFrame( n1=1:9, cat=\[ 'A','B','A', 'B','C','B', 'C','A','C' \] ); julia\> groupby(df, :cat) GroupedDataFrame{DataFrame} with 3 groups based on key: :cat Fi…

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## [Displaying plots in VegaLite opens vscode](https://discourse.julialang.org/t/displaying-plots-in-vegalite-opens-vscode/18336)

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**Author:** [@Ali\_Vahdati](https://discourse.julialang.org/u/Ali_Vahdati)\
**Replies:** 5\
**Last updated:** [December 6, 2018, 2:57pm UTC](https://discourse.julialang.org/t/displaying-plots-in-vegalite-opens-vscode/18336 "2018-12-06T14:57:50Z")

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I have no idea what configuration is wrong, but when I try to display a simple plot from VegaLite, a new instance of vscode opens. It happens when I do: using VegaLite, VegaDatasets data = dataset("cars") data |\> @vlpl…

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## [Fitting multilevel generalized linear models](https://discourse.julialang.org/t/fitting-multilevel-generalized-linear-models/18350)

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**Author:** [@jbrea](https://discourse.julialang.org/u/jbrea)\
**Replies:** 3\
**Last updated:** [December 6, 2018, 1:56pm UTC](https://discourse.julialang.org/t/fitting-multilevel-generalized-linear-models/18350 "2018-12-06T13:56:55Z")

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Is there already a julia package to fit multilevel models, e.g. for repeated measures?

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## [How does one use empirical distributions?](https://discourse.julialang.org/t/how-does-one-use-empirical-distributions/18360)

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**Author:** [@iwelch](https://discourse.julialang.org/u/iwelch)\
**Replies:** 1\
**Last updated:** [December 6, 2018, 4:41am UTC](https://discourse.julialang.org/t/how-does-one-use-empirical-distributions/18360 "2018-12-06T04:41:04Z")

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dear stats experts—the following used to work. julia\> using Random, Distributions; Random.seed!(0); julia\> x= max.(randn(10000), (rand(10000) .- 0.5)); julia\> empcdfun= EmpiricalUnivariateDistribution( x ); julia\> c…

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## [Another error with defining Flux.jl gradients](https://discourse.julialang.org/t/another-error-with-defining-flux-jl-gradients/17803)

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**Author:** [@xiaodai](https://discourse.julialang.org/u/xiaodai)\
**Replies:** 5\
**Last updated:** [December 5, 2018, 4:09pm UTC](https://discourse.julialang.org/t/another-error-with-defining-flux-jl-gradients/17803 "2018-12-05T16:09:50Z")

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Here is the MWE x = rand(12, 1000) y = rand(1000) W = param(\[1 for i=1:12\]) a = param(\[0.5\]) b = param(\[0.5\]) model(x) = begin x1 = \[maximum(x\[:,j\] .\* W) for j in 1:size(x, 2)\] (a .+ (x1 .- StatsBase.mean(x1)).…

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## [Animation on Julia 1.0.x](https://discourse.julialang.org/t/animation-on-julia-1-0-x/18270)

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**Author:** [@HerAdri](https://discourse.julialang.org/u/HerAdri)\
**Replies:** 18\
**Last updated:** [December 5, 2018, 3:24pm UTC](https://discourse.julialang.org/t/animation-on-julia-1-0-x/18270 "2018-12-05T15:24:48Z")

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I try to reproduce the following two examples in Julia 1.0.2,: using Plots anim = Animation() p = plot(\[sin,cos\], 0, π, size=(300,300)) scatter!(\[0\], \[sin,cos\]) for i in 0:0.1:π p\[3\] = \[i\], \[sin(i)\] p\[4\] = \[i\], …

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## [Problems about dealing with missing values, maybe connected to DataFrames.jl](https://discourse.julialang.org/t/problems-about-dealing-with-missing-values-maybe-connected-to-dataframes-jl/18282)

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**Author:** [@Jaime](https://discourse.julialang.org/u/Jaime)\
**Replies:** 4\
**Last updated:** [December 4, 2018, 5:32pm UTC](https://discourse.julialang.org/t/problems-about-dealing-with-missing-values-maybe-connected-to-dataframes-jl/18282 "2018-12-04T17:32:54Z")

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julia\> a=DataFrame(\[1 2 3; 4 missing 6\]) 2×3 DataFrame │ Row │ x1 │ x2 │ x3 │ │ │ Int64⍰ │ Int64⍰ │ Int64⍰ │ ├─────┼────────┼─────────┼────────┤ │ 1 │ 1 │ 2 │ 3 │ │ 2 │ 4 │ miss…

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## [\\ left division operator in editors (emacs)](https://discourse.julialang.org/t/left-division-operator-in-editors-emacs/18225)

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**Author:** [@jlapeyre](https://discourse.julialang.org/u/jlapeyre)\
**Replies:** 5\
**Last updated:** [December 4, 2018, 12:00pm UTC](https://discourse.julialang.org/t/left-division-operator-in-editors-emacs/18225 "2018-12-04T12:00:00Z")

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This operator \\ puts my emacs julia-mode in a bad state. After this symbol, it no longer understands expressions. If I want to use it, or add methods, I do eval(Meta.parse("import Base: \\\\")) const left\_division = eval…

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## [CUDAnative is awesome!](https://discourse.julialang.org/t/cudanative-is-awesome/17861)

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**Author:** [@LaurentPlagne](https://discourse.julialang.org/u/LaurentPlagne)\
**Replies:** 12\
**Last updated:** [December 3, 2018, 10:47pm UTC](https://discourse.julialang.org/t/cudanative-is-awesome/17861 "2018-12-03T22:47:11Z")

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Hi, I have just finished to rewrite my FEM solver with CUDAnative.jl and I want to address a big thank you to Tim and all the contributors for this package ! The performance is on par with the native C++/CUDA implement…

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## [Plotting with JuMP variables](https://discourse.julialang.org/t/plotting-with-jump-variables/18255)

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**Author:** [@muriloasouza](https://discourse.julialang.org/u/muriloasouza)\
**Replies:** 2\
**Last updated:** [December 3, 2018, 5:58pm UTC](https://discourse.julialang.org/t/plotting-with-jump-variables/18255 "2018-12-03T17:58:45Z")

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Hello, Not sure if i should post this here or in the visualization domain… but how can i plot a bar graph that has JuMP variables and regular Julia variables? For example, i’m trying to plot a bargraph, like this: Usi…

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## [Best practice for executing many instances parallel](https://discourse.julialang.org/t/best-practice-for-executing-many-instances-parallel/18107)

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**Author:** [@mike\_k](https://discourse.julialang.org/u/mike_k)\
**Replies:** 8\
**Last updated:** [December 3, 2018, 1:31pm UTC](https://discourse.julialang.org/t/best-practice-for-executing-many-instances-parallel/18107 "2018-12-03T13:31:05Z")

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Dear community, as indicated in the title, I would like to run many (thousands) of computational experiments on a hpc-cluster using julia code. Notice that I’m new to julia, so hopefully there are better options than th…

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## [Differential equation solver example gives an error: MethodError: no method matching OrdinaryDiffEq.DEOptions](https://discourse.julialang.org/t/differential-equation-solver-example-gives-an-error-methoderror-no-method-matching-ordinarydiffeq-deoptions/18001)

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**Author:** [@PeterXG](https://discourse.julialang.org/u/PeterXG)\
**Replies:** 6\
**Last updated:** [December 3, 2018, 12:32pm UTC](https://discourse.julialang.org/t/differential-equation-solver-example-gives-an-error-methoderror-no-method-matching-ordinarydiffeq-deoptions/18001 "2018-12-03T12:32:48Z")

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Dear All, I run the sample code to solve a differential equation from tutorial. const p0 = 0.2; const q0 = 0.3; const v0 = 1; const d0 = 5 const p1 = 0.2; const q1 = 0.3; const v1 = 1; const d1 = 1 const d2 = 1; const …

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## [Difficulties with DifferentialEquations package](https://discourse.julialang.org/t/difficulties-with-differentialequations-package/18204)

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**Author:** [@BLI](https://discourse.julialang.org/u/BLI)\
**Replies:** 13\
**Last updated:** [December 2, 2018, 9:14pm UTC](https://discourse.julialang.org/t/difficulties-with-differentialequations-package/18204 "2018-12-02T21:14:33Z")

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I’m testing the DifferentialEquations package on a model I developed ca. 1993 (just dug it of the archives…). I try to simulate 5 Argon molecules bouncing around in 2D, locked up between “Lennard-Jones” like potential wa…

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## [Difficulty to understand the JuMP problem setting](https://discourse.julialang.org/t/difficulty-to-understand-the-jump-problem-setting/18112)

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**Author:** [@Tero\_Frondelius](https://discourse.julialang.org/u/Tero_Frondelius)\
**Replies:** 13\
**Last updated:** [December 2, 2018, 5:50pm UTC](https://discourse.julialang.org/t/difficulty-to-understand-the-jump-problem-setting/18112 "2018-12-02T17:50:51Z")

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Here is my MWE of the problem: using JuMP using Clp Random.seed!(2017) xlocs, ylocs = rand(5), rand(5) function demo\_problem(x,y) counter = 0 for (xx,yy) in zip(x,y) val = xx - yy if (…

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## [How to render multiple windows in Makie.jl?](https://discourse.julialang.org/t/how-to-render-multiple-windows-in-makie-jl/18221)

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**Author:** [@NanFangHong](https://discourse.julialang.org/u/NanFangHong)\
**Replies:** 0\
**Last updated:** [December 2, 2018, 3:29pm UTC](https://discourse.julialang.org/t/how-to-render-multiple-windows-in-makie-jl/18221 "2018-12-02T15:29:06Z")

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Hi, may I have your help? How to render multiple windows in Makie.jl?

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## [User defined objective function to run MICP](https://discourse.julialang.org/t/user-defined-objective-function-to-run-micp/16992)

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**Author:** [@coiacy](https://discourse.julialang.org/u/coiacy)\
**Replies:** 18\
**Last updated:** [December 2, 2018, 11:01am UTC](https://discourse.julialang.org/t/user-defined-objective-function-to-run-micp/16992 "2018-12-02T11:01:21Z")

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I have the following objective function (w is the variable vector of size nx): function obj\_trace(w::Array{Float64,1}) dg = Diagonal(w) M = F' \* (gamma \\ dg) \* F + eye(nx) obj = trace(inv(M)) return obj …

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