# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=548

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**Page:** 549

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## [Simple PDE benchmark](https://discourse.julialang.org/t/simple-pde-benchmark/7430)

<div class="topic-metadata">

**Author:** [@antoine-levitt](https://discourse.julialang.org/u/antoine-levitt)\
**Replies:** 14\
**Last updated:** [December 1, 2017, 5:53pm UTC](https://discourse.julialang.org/t/simple-pde-benchmark/7430 "2017-12-01T17:53:19Z")

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Hi, I made a simple benchmark to try and convince colleagues to switch to Julia. It might be of interest to people, so here it is : https://github.com/antoine-levitt/benchmark\_heat. It’s the most simple PDE code I could…

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## [(Integrated) autocorrelation time](https://discourse.julialang.org/t/integrated-autocorrelation-time/7403)

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**Author:** [@Sleort](https://discourse.julialang.org/u/Sleort)\
**Replies:** 6\
**Last updated:** [December 1, 2017, 3:34am UTC](https://discourse.julialang.org/t/integrated-autocorrelation-time/7403 "2017-12-01T03:34:36Z")

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I could not find any (integrated) autocorrelation time estimator in the basic statistics packages\*, so I made a crude implementation myself based on StatsBase.autocor and the tips given in http://www.stat.unc.edu/faculty…

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## [Force a gradient value at a degenerate point](https://discourse.julialang.org/t/force-a-gradient-value-at-a-degenerate-point/7418)

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**Author:** [@vepiteski](https://discourse.julialang.org/u/vepiteski)\
**Replies:** 1\
**Last updated:** [December 1, 2017, 1:34am UTC](https://discourse.julialang.org/t/force-a-gradient-value-at-a-degenerate-point/7418 "2017-12-01T01:34:55Z")

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I wish to implement Wolfe’s example x0 = \[0; 0.25; 0.0\] lb = \[0.0; 0.0; 0.0\] ub = \[Inf; Inf; 2.0\] @variable(nlp, lb\[i\] \<= x\[i = 1:3\] \<= ub\[i\], start = x0\[i\]) @NLobjective( nlp, Min, 4/3\*(x\[1\]^2 - x\[1\] \* x…

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## [NLopt stopval and termination criteria](https://discourse.julialang.org/t/nlopt-stopval-and-termination-criteria/7333)

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**Author:** [@ivborissov](https://discourse.julialang.org/u/ivborissov)\
**Replies:** 3\
**Last updated:** [November 30, 2017, 3:24pm UTC](https://discourse.julialang.org/t/nlopt-stopval-and-termination-criteria/7333 "2017-11-30T15:24:39Z")

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Hi, I am solving optimization problems like find max x1 in \[a1,b1\] : f(x1,x2,x3...)\<=0 plus I know that at initial point f(a1,a2,a3...)\<=0. Sometimes my model f (based on experimental data) isn’t sensitive to x1 (like …

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## [Using Math Functions Inside CUDA Kernel](https://discourse.julialang.org/t/using-math-functions-inside-cuda-kernel/7411)

<div class="topic-metadata">

**Author:** [@drjoke](https://discourse.julialang.org/u/drjoke)\
**Replies:** 1\
**Last updated:** [November 30, 2017, 2:15pm UTC](https://discourse.julialang.org/t/using-math-functions-inside-cuda-kernel/7411 "2017-11-30T14:15:31Z")

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using CUDAdrv, CUDAnative function kernel\_a(a) i = (blockIdx().x-1) \* blockDim().x + threadIdx().x a\[i\] = tanh(a\[i\]) return nothing end dev = CuDevice(0) ctx = CuContext(dev) len = 100 a = rand(Float32, len…

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## [Maybe an area the Julia folks may want to explore](https://discourse.julialang.org/t/maybe-an-area-the-julia-folks-may-want-to-explore/7410)

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**Author:** [@Frank\_Applin](https://discourse.julialang.org/u/Frank_Applin)\
**Replies:** 0\
**Last updated:** [November 30, 2017, 1:47pm UTC](https://discourse.julialang.org/t/maybe-an-area-the-julia-folks-may-want-to-explore/7410 "2017-11-30T13:47:30Z")

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Developers use 750 Raspberry Pi boards as supercomputing testbed

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## [Announcement: updates to NEOS.jl](https://discourse.julialang.org/t/announcement-updates-to-neos-jl/7395)

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**Author:** [@odow](https://discourse.julialang.org/u/odow)\
**Replies:** 3\
**Last updated:** [November 30, 2017, 5:22am UTC](https://discourse.julialang.org/t/announcement-updates-to-neos-jl/7395 "2017-11-30T05:22:54Z")

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NEOS.jl is a Julia interface to the NEOS Server, a free internet-based service for solving numerical optimization problems. In addition to wrapping the XML-RPC interface, NEOS.jl provides a MathProgBase solver that can …

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## [DistributedArrays: unexpected behavior before modifying localpart](https://discourse.julialang.org/t/distributedarrays-unexpected-behavior-before-modifying-localpart/7355)

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**Author:** [@mikeT](https://discourse.julialang.org/u/mikeT)\
**Replies:** 1\
**Last updated:** [November 29, 2017, 4:33pm UTC](https://discourse.julialang.org/t/distributedarrays-unexpected-behavior-before-modifying-localpart/7355 "2017-11-29T16:33:33Z")

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I have been trying to learn enough about distributed arrays to solving a simple PDE in parallel; however, there appears to be an error associated with accessing localpart data right before modifying it. I’m trying to un…

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## [Is there no standard way to read files with fixed width columns in the new DataFrames ecosystem?](https://discourse.julialang.org/t/is-there-no-standard-way-to-read-files-with-fixed-width-columns-in-the-new-dataframes-ecosystem/7324)

<div class="topic-metadata">

**Author:** [@NickNack](https://discourse.julialang.org/u/NickNack)\
**Replies:** 6\
**Last updated:** [November 29, 2017, 11:32am UTC](https://discourse.julialang.org/t/is-there-no-standard-way-to-read-files-with-fixed-width-columns-in-the-new-dataframes-ecosystem/7324 "2017-11-29T11:32:25Z")

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I’ve been using DataFrames.readtable() to read files with fixed width columns, but that function is now deprecated in favor of CSV.read(). However it seems that CSV.read() lacks the flag to “treat consecutive whitespace …

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## [Eigfact and eigen in R seems does not match](https://discourse.julialang.org/t/eigfact-and-eigen-in-r-seems-does-not-match/7341)

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**Author:** [@babaq](https://discourse.julialang.org/u/babaq)\
**Replies:** 5\
**Last updated:** [November 28, 2017, 5:58am UTC](https://discourse.julialang.org/t/eigfact-and-eigen-in-r-seems-does-not-match/7341 "2017-11-28T05:58:24Z")

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In the process of converting some R code to Julia, i found the matrix Eigen decomposition produce different result compared to R. the following code is tested in Julia 0.6, and R 3.3.3 through RCall 0.8.1 using RCall a=…

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## [Announcement: breaking changes in AmplNLWriter.jl v0.4.0](https://discourse.julialang.org/t/announcement-breaking-changes-in-amplnlwriter-jl-v0-4-0/7342)

<div class="topic-metadata">

**Author:** [@odow](https://discourse.julialang.org/u/odow)\
**Replies:** 0\
**Last updated:** [November 28, 2017, 1:22am UTC](https://discourse.julialang.org/t/announcement-breaking-changes-in-amplnlwriter-jl-v0-4-0/7342 "2017-11-28T01:22:50Z")

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Version 0.4.0 of AmplNLWriter.jl introduces a major breaking change for users: BonminNLSolver(), CouenneNLSolver(), and IpoptNLSolver() have been removed and will now throw an error. Users of Bonmin and Couenne should c…

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## [AxisArray plotted by Plots.jl](https://discourse.julialang.org/t/axisarray-plotted-by-plots-jl/3972)

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**Author:** [@phlavenk](https://discourse.julialang.org/u/phlavenk)\
**Replies:** 5\
**Last updated:** [November 27, 2017, 3:14pm UTC](https://discourse.julialang.org/t/axisarray-plotted-by-plots-jl/3972 "2017-11-27T15:14:25Z")

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Hi, is there a way to display an image defined using AxisArray into a plot with XY axes and scaled properly? using Images, ImageAxes, Plots img = colorview(Gray, reshape(linspace(0,1, 10000), 100, 100)) imx = AxisArray…

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## [Pmap: does it copy or share arguments across processes?](https://discourse.julialang.org/t/pmap-does-it-copy-or-share-arguments-across-processes/7317)

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**Author:** [@drjoke](https://discourse.julialang.org/u/drjoke)\
**Replies:** 9\
**Last updated:** [November 26, 2017, 4:34pm UTC](https://discourse.julialang.org/t/pmap-does-it-copy-or-share-arguments-across-processes/7317 "2017-11-26T16:34:02Z")

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for (name, security) in dataset.securities push!(arg\_array, (name, data\[name\])) end tuples = pmap(extract\_variables, arg\_array) In the above code, data\[name\]) is a Dict{Int64, Float32} that contains a lot of data. …

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## [Pretty printing of tables](https://discourse.julialang.org/t/pretty-printing-of-tables/7254)

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**Author:** [@Rafal\_Machalica](https://discourse.julialang.org/u/Rafal_Machalica)\
**Replies:** 7\
**Last updated:** [November 26, 2017, 12:06am UTC](https://discourse.julialang.org/t/pretty-printing-of-tables/7254 "2017-11-26T00:06:09Z")

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I’m looking for a quick solution of printing human-readable 2D tables. I thought I found a solution - NamedArrays. It meets my needs in terms of formatting, however when the table is slightly bigger (but still could fit …

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## [Weighted covariance, how to compute?](https://discourse.julialang.org/t/weighted-covariance-how-to-compute/7282)

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**Author:** [@programista](https://discourse.julialang.org/u/programista)\
**Replies:** 9\
**Last updated:** [November 25, 2017, 9:02am UTC](https://discourse.julialang.org/t/weighted-covariance-how-to-compute/7282 "2017-11-25T09:02:23Z")

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If d is data set and k,l=size(d) cov = d’\*d/k-mean(d,1)'\*mean(d,1) It is nice formula , But how to compute the cov if any row is weighted by vector w ? Paul

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## [Is there light at the end of the DataFrames tunnel?](https://discourse.julialang.org/t/is-there-light-at-the-end-of-the-dataframes-tunnel/6382)

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**Author:** [@dmbates](https://discourse.julialang.org/u/dmbates)\
**Replies:** 36\
**Last updated:** [November 24, 2017, 8:44pm UTC](https://discourse.julialang.org/t/is-there-light-at-the-end-of-the-dataframes-tunnel/6382 "2017-11-24T20:44:27Z")

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I keep trying to experiment with a version of the “DataFrames of the future”, as I understand it. So I would like to have a development version of DataFrames 0.11.0 combined with versions of Nulls, CategoricalArrays, CS…

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## [\[ANN\] Schemata.jl (alpha)](https://discourse.julialang.org/t/ann-schemata-jl-alpha/7287)

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**Author:** [@jocklawrie](https://discourse.julialang.org/u/jocklawrie)\
**Replies:** 0\
**Last updated:** [November 24, 2017, 11:56am UTC](https://discourse.julialang.org/t/ann-schemata-jl-alpha/7287 "2017-11-24T11:56:25Z")

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Hi all, Here’s a package I’ve started as part of a larger project that I am beating into shape. It’s not yet registered, so you’ll need to clone it from here. I thought I’d put it out early because there has been much …

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## [Addprocs with ssh does not work on 0.6.1](https://discourse.julialang.org/t/addprocs-with-ssh-does-not-work-on-0-6-1/7253)

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**Author:** [@usefulhyun](https://discourse.julialang.org/u/usefulhyun)\
**Replies:** 3\
**Last updated:** [November 24, 2017, 7:06am UTC](https://discourse.julialang.org/t/addprocs-with-ssh-does-not-work-on-0-6-1/7253 "2017-11-24T07:06:50Z")

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Hi, there! My code works well on 0.6.0. However, after upgrading it to 0.6.1 addprocs function does not work when I create a process on remote machine. I tried to add a kwarg tunnel=true to be addprocs(\[“remotehost”\];…

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## [Deployment questions: AOT and Portability](https://discourse.julialang.org/t/deployment-questions-aot-and-portability/7262)

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**Author:** [@drjoke](https://discourse.julialang.org/u/drjoke)\
**Replies:** 5\
**Last updated:** [November 23, 2017, 12:49pm UTC](https://discourse.julialang.org/t/deployment-questions-aot-and-portability/7262 "2017-11-23T12:49:41Z")

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AOT: Is it possible to enable AOT compilation? It takes around 10 seconds to compile the kernel. Compilation happens every time even when I rarely change the kernel. Portability: When I run the code on a machine without…

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## [Understanding Blocks and Threads](https://discourse.julialang.org/t/understanding-blocks-and-threads/7249)

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**Author:** [@drjoke](https://discourse.julialang.org/u/drjoke)\
**Replies:** 2\
**Last updated:** [November 23, 2017, 6:03am UTC](https://discourse.julialang.org/t/understanding-blocks-and-threads/7249 "2017-11-23T06:03:54Z")

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I got CUDAnative to work on a MacBook Pro 2016 on High Sierra with GeForce 1080 Ti running as an eGPU connected via USB-C. Everything works great so far, but I need help understanding on how Blocks and Threads work in g…

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## [Adding random noise to color images](https://discourse.julialang.org/t/adding-random-noise-to-color-images/7206)

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**Author:** [@Phil\_Tomson](https://discourse.julialang.org/u/Phil_Tomson)\
**Replies:** 4\
**Last updated:** [November 22, 2017, 7:48pm UTC](https://discourse.julialang.org/t/adding-random-noise-to-color-images/7206 "2017-11-22T19:48:02Z")

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What would be the best way to go about adding random noise to a color image using Julia? Does Images.jl have a way to do this?

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## [Can't install MakiE](https://discourse.julialang.org/t/cant-install-makie/7230)

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**Author:** [@danielc](https://discourse.julialang.org/u/danielc)\
**Replies:** 10\
**Last updated:** [November 22, 2017, 6:54pm UTC](https://discourse.julialang.org/t/cant-install-makie/7230 "2017-11-22T18:54:37Z")

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I am trying to install MakiE on Julia 0.6 but the package doesn’t seem to be available: julia\> Pkg.add("Makie") ERROR: unknown package Makie I just want to test it and figure out how it works.

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## [Does constructing SharedArray always fill the values with zeros?](https://discourse.julialang.org/t/does-constructing-sharedarray-always-fill-the-values-with-zeros/7247)

<div class="topic-metadata">

**Author:** [@usefulhyun](https://discourse.julialang.org/u/usefulhyun)\
**Replies:** 0\
**Last updated:** [November 22, 2017, 2:21pm UTC](https://discourse.julialang.org/t/does-constructing-sharedarray-always-fill-the-values-with-zeros/7247 "2017-11-22T14:21:09Z")

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Does constructing SharedArray always fill the values with zeros? I have tested on my laptop, all creating returns an object filled with zeros. I wonder if this is guaranteed behavior.

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## [When "if (a\<b) x=1/(a-b)" divides by zero](https://discourse.julialang.org/t/when-if-a-b-x-1-a-b-divides-by-zero/7154)

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**Author:** [@certik](https://discourse.julialang.org/u/certik)\
**Replies:** 4\
**Last updated:** [November 22, 2017, 12:59am UTC](https://discourse.julialang.org/t/when-if-a-b-x-1-a-b-divides-by-zero/7154 "2017-11-22T00:59:25Z")

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This came up in https://github.com/JuliaLang/julia/issues/24568, specifically this comment https://github.com/JuliaLang/julia/issues/24568#issuecomment-345004303. The question was, just looking at a code float X, XMin, …

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## [How to drop NA values with Query.jl?](https://discourse.julialang.org/t/how-to-drop-na-values-with-query-jl/7231)

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**Author:** [@juliohm](https://discourse.julialang.org/u/juliohm)\
**Replies:** 2\
**Last updated:** [November 21, 2017, 11:04pm UTC](https://discourse.julialang.org/t/how-to-drop-na-values-with-query-jl/7231 "2017-11-21T23:04:16Z")

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Could you please explain why this code snippet doesn’t work? using DataFrames, Query df = DataFrame(a=\[1,2,3\], b=@data \[NA,2,3\]) @from i in df begin @where !isequal(i.b, NA) @select i @collect DataFrame en…

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## [Is it possible for Julia to gradually replace C++ in financial numerical computation?](https://discourse.julialang.org/t/is-it-possible-for-julia-to-gradually-replace-c-in-financial-numerical-computation/7222)

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**Author:** [@Yifan\_Liu](https://discourse.julialang.org/u/Yifan_Liu)\
**Replies:** 3\
**Last updated:** [November 21, 2017, 10:42pm UTC](https://discourse.julialang.org/t/is-it-possible-for-julia-to-gradually-replace-c-in-financial-numerical-computation/7222 "2017-11-21T22:42:17Z")

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I just noticed that Professor Mark Joshi passed away last month, and I have really benefited from his book C++ Design Patterns and Derivatives Pricing when I was dong my master’s degree. I was wondering if it is possibl…

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## [Where is actual development in Plotting?](https://discourse.julialang.org/t/where-is-actual-development-in-plotting/6224)

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**Author:** [@lobingera](https://discourse.julialang.org/u/lobingera)\
**Replies:** 161\
**Last updated:** [November 21, 2017, 6:41pm UTC](https://discourse.julialang.org/t/where-is-actual-development-in-plotting/6224 "2017-11-21T18:41:19Z")

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i followed a little bit What can we do to make Julia grow fast? and (as usual) a long term issue of usability of plotting shows up. So i looked around a little bit on the actual packages, but (maybe it’s an observer prob…

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## [Multiobjective optimization with vOptGeneric](https://discourse.julialang.org/t/multiobjective-optimization-with-voptgeneric/6878)

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**Author:** [@UserMorocco](https://discourse.julialang.org/u/UserMorocco)\
**Replies:** 2\
**Last updated:** [November 21, 2017, 4:29pm UTC](https://discourse.julialang.org/t/multiobjective-optimization-with-voptgeneric/6878 "2017-11-21T16:29:14Z")

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Hello, How to use vOptGeneric for three objectives ? Thanks

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## [What does data communication via RemoteChannel block?](https://discourse.julialang.org/t/what-does-data-communication-via-remotechannel-block/7218)

<div class="topic-metadata">

**Author:** [@usefulhyun](https://discourse.julialang.org/u/usefulhyun)\
**Replies:** 1\
**Last updated:** [November 21, 2017, 2:32pm UTC](https://discourse.julialang.org/t/what-does-data-communication-via-remotechannel-block/7218 "2017-11-21T14:32:19Z")

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Hi, there! I use RemoteChannels as Communication Queues between processes. My problem is that tasks who are receiving and sending data via RemoteChannels using put! or take! do not surrender its control until data tra…

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## [Http://juliastats.org domain seems to have expired?](https://discourse.julialang.org/t/http-juliastats-org-domain-seems-to-have-expired/7192)

<div class="topic-metadata">

**Author:** [@NaOH](https://discourse.julialang.org/u/NaOH)\
**Replies:** 9\
**Last updated:** [November 21, 2017, 1:19pm UTC](https://discourse.julialang.org/t/http-juliastats-org-domain-seems-to-have-expired/7192 "2017-11-21T13:19:22Z")

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Dear JuliaStats team, I just wanted to let you know that it seems the jluiastats.org domain name seems to have expired: http://www.juliastats.org And now it redirects to some random page. Is there somewhere I can d…

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