# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1623

[Latest](https://discourse.julialang.org/latest.md) · [Categories](https://discourse.julialang.org/categories.md) · [Tags](https://discourse.julialang.org/tags.md)

**Page:** 1624

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## [Lazy representation of x^T A x](https://discourse.julialang.org/t/lazy-representation-of-x-t-a-x/47087)

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**Author:** [@mleprovost](https://discourse.julialang.org/u/mleprovost)\
**Replies:** 6\
**Last updated:** [September 22, 2020, 8:36pm UTC](https://discourse.julialang.org/t/lazy-representation-of-x-t-a-x/47087 "2020-09-22T20:36:21Z")

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Hello, I have a complicated code (nested calls to subroutines) that computes an expression of the form x^T A x, where A is not necessarily PSD. Is it possible to construct a lazy representation of A, in the same spirit …

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## [State of the Art in Combinator Parsers?](https://discourse.julialang.org/t/state-of-the-art-in-combinator-parsers/40935)

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**Author:** [@tro3](https://discourse.julialang.org/u/tro3)\
**Replies:** 8\
**Last updated:** [September 22, 2020, 8:30pm UTC](https://discourse.julialang.org/t/state-of-the-art-in-combinator-parsers/40935 "2020-09-22T20:30:10Z")

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I have need of parsing in a few different languages, so I sat down to find the Julia equivalent of Parsec (Haskell) or pyparsing (Python). There is ParserCombinator.jl, but does not appear to be maintained (or functiona…

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## [Julia PPL survey paper?](https://discourse.julialang.org/t/julia-ppl-survey-paper/44879)

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**Author:** [@cscherrer](https://discourse.julialang.org/u/cscherrer)\
**Replies:** 15\
**Last updated:** [September 22, 2020, 8:29pm UTC](https://discourse.julialang.org/t/julia-ppl-survey-paper/44879 "2020-09-22T20:29:02Z")

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Would it be feasible for the Julia PPL community to collaborate on a survey article? It could cover things like Why Julia is great for PPL Overview of current approaches and the general design space Opportunities for “…

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## [WebIO unresponsive over Apache proxy](https://discourse.julialang.org/t/webio-unresponsive-over-apache-proxy/47091)

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**Author:** [@cstjean](https://discourse.julialang.org/u/cstjean)\
**Replies:** 0\
**Last updated:** [September 22, 2020, 7:02pm UTC](https://discourse.julialang.org/t/webio-unresponsive-over-apache-proxy/47091 "2020-09-22T19:02:07Z")

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We have this WebIO app of which we’re trying to run multiple instances, each with its own Julia process. So myserver/app1 is served by process 1 at myserver:8001, and so on for app2, 3 etc. The Apache config looks like …

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## [DecFP.jl no longer precompiling on Julia v1.6 (master)](https://discourse.julialang.org/t/decfp-jl-no-longer-precompiling-on-julia-v1-6-master/47032)

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**Author:** [@ScottPJones](https://discourse.julialang.org/u/ScottPJones)\
**Replies:** 3\
**Last updated:** [September 22, 2020, 4:58pm UTC](https://discourse.julialang.org/t/decfp-jl-no-longer-precompiling-on-julia-v1-6-master/47032 "2020-09-22T16:58:16Z")

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julia\> using DecFP \[ Info: Precompiling DecFP \[55939f99-70c6-5e9b-8bb0-5071ed7d61fd\] ERROR: LoadError: UndefVarError: libbid not defined Stacktrace: \[1\] \_parse(#unused#::Type{DecFP.Dec32}, s::String) @ DecFP ~/.julia…

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## [Collect(a) vs. \[a;\]](https://discourse.julialang.org/t/collect-a-vs-a/47055)

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**Author:** [@remi-garcia](https://discourse.julialang.org/u/remi-garcia)\
**Replies:** 10\
**Last updated:** [September 22, 2020, 4:15pm UTC](https://discourse.julialang.org/t/collect-a-vs-a/47055 "2020-09-22T16:15:49Z")

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Hi, I don’t get the difference between collect(a) and \[a;\] for ranges. julia\> typeof(collect(5:7)) === typeof(\[5:7;\]) true julia\> collect(5:7) == \[5:7;\] true julia\> collect(5:7) 3-element Array{Int64,1}: 5 6 7 ju…

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## [HTTP.jl no longer precompiling on Julia v1.6 (i.e. master)](https://discourse.julialang.org/t/http-jl-no-longer-precompiling-on-julia-v1-6-i-e-master/47028)

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**Author:** [@ScottPJones](https://discourse.julialang.org/u/ScottPJones)\
**Replies:** 4\
**Last updated:** [September 22, 2020, 4:10pm UTC](https://discourse.julialang.org/t/http-jl-no-longer-precompiling-on-julia-v1-6-i-e-master/47028 "2020-09-22T16:10:24Z")

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Sometime within the last week or two, it seems that HTTP.jl will no longer precompile on a recently built Julia. julia\> using HTTP \[ Info: Precompiling HTTP \[cd3eb016-35fb-5094-929b-558a96fad6f3\] ERROR: LoadError: LoadE…

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## [Jump Xpress - Problem with "MAXTIME" parameter](https://discourse.julialang.org/t/jump-xpress-problem-with-maxtime-parameter/45821)

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**Author:** [@Tmart](https://discourse.julialang.org/u/Tmart)\
**Replies:** 10\
**Last updated:** [September 22, 2020, 3:22pm UTC](https://discourse.julialang.org/t/jump-xpress-problem-with-maxtime-parameter/45821 "2020-09-22T15:22:41Z")

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Hello, When I set the parameter “MAXTIME” for a optimization problem in JUMP with the XPress solver, I have the error “DimensionMismatch(“array could not be broadcast to match destination”)”. However, in the output file…

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## [How to find missing dependencies of .jl file without executing it](https://discourse.julialang.org/t/how-to-find-missing-dependencies-of-jl-file-without-executing-it/47049)

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**Author:** [@pauljurczak](https://discourse.julialang.org/u/pauljurczak)\
**Replies:** 8\
**Last updated:** [September 22, 2020, 2:54pm UTC](https://discourse.julialang.org/t/how-to-find-missing-dependencies-of-jl-file-without-executing-it/47049 "2020-09-22T14:54:15Z")

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I have a program consisting of a single .jl file, which is using a bunch of packages with directive using. There is more of them than absolutely necessary, since sometimes it’s not clear from documentation what is the ba…

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## [Plot the following table Please](https://discourse.julialang.org/t/plot-the-following-table-please/46714)

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**Author:** [@Mun\_Barimukh](https://discourse.julialang.org/u/Mun_Barimukh)\
**Replies:** 13\
**Last updated:** [September 22, 2020, 2:36pm UTC](https://discourse.julialang.org/t/plot-the-following-table-please/46714 "2020-09-22T14:36:00Z")

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\[{“metadata”:{“trusted”:true},“cell\_type”:“code”,“source”:“using DataFrames;df = DataFrame(m)”,“execution\_count”:14,“outputs”:\[{“data”:{“text/html”:" 40 rows × 3 columns (omitted printing of 1 columns) shoename sh…

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## [Activate project in multiple cores when running script from command line](https://discourse.julialang.org/t/activate-project-in-multiple-cores-when-running-script-from-command-line/47074)

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**Author:** [@AAL](https://discourse.julialang.org/u/AAL)\
**Replies:** 0\
**Last updated:** [September 22, 2020, 2:32pm UTC](https://discourse.julialang.org/t/activate-project-in-multiple-cores-when-running-script-from-command-line/47074 "2020-09-22T14:32:16Z")

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I have a project folder with a package that can make computations in parallel processes and a script that makes use of the package. Because I want my script to run in parallel I need to load the package in all process, s…

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## [Add support for ' (thousands separator) for Printf](https://discourse.julialang.org/t/add-support-for-thousands-separator-for-printf/47030)

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**Author:** [@ScottPJones](https://discourse.julialang.org/u/ScottPJones)\
**Replies:** 3\
**Last updated:** [September 22, 2020, 2:31pm UTC](https://discourse.julialang.org/t/add-support-for-thousands-separator-for-printf/47030 "2020-09-22T14:31:06Z")

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Printf, even after the (very nice) rewrite, does not support the ' thousands separator flag (it is a GNU extension). Would a PR adding that be accepted? It’s very nice funcionality to have in practice.

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## [Reading images in HTTP doesn't seem to terminate](https://discourse.julialang.org/t/reading-images-in-http-doesnt-seem-to-terminate/47059)

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**Author:** [@xiaodai](https://discourse.julialang.org/u/xiaodai)\
**Replies:** 4\
**Last updated:** [September 22, 2020, 2:25pm UTC](https://discourse.julialang.org/t/reading-images-in-http-doesnt-seem-to-terminate/47059 "2020-09-22T14:25:26Z")

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using HTTP using Colors # initialize to nothing orig\_img = nothing using ImageMagick HTTP.listen() do http::HTTP.Stream global orig\_img @show http.message @show HTTP.header(http, "Content-Type") while …

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## [How do I make a dynamic website with the help of genie.jl?](https://discourse.julialang.org/t/how-do-i-make-a-dynamic-website-with-the-help-of-genie-jl/47072)

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**Author:** [@babaid](https://discourse.julialang.org/u/babaid)\
**Replies:** 0\
**Last updated:** [September 22, 2020, 2:18pm UTC](https://discourse.julialang.org/t/how-do-i-make-a-dynamic-website-with-the-help-of-genie-jl/47072 "2020-09-22T14:18:07Z")

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I recently started with genie.jl, and I would like to know how I can manage so everything works together. My first test project would be a page where a user can sign up, and another where he can login. My question would …

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## [Define/plot robot workspace](https://discourse.julialang.org/t/define-plot-robot-workspace/47026)

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**Author:** [@heliosdrm](https://discourse.julialang.org/u/heliosdrm)\
**Replies:** 1\
**Last updated:** [September 22, 2020, 1:09pm UTC](https://discourse.julialang.org/t/define-plot-robot-workspace/47026 "2020-09-22T13:09:17Z")

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Hi, I would like to have advice about what packages might I look at, in order to visualize the workspace of a robot, as done with Matlab in this paper. It’s not necessary to solve the whole problem. Say I already have t…

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## [Whos element of vector y is in Set x](https://discourse.julialang.org/t/whos-element-of-vector-y-is-in-set-x/47065)

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**Author:** [@programista](https://discourse.julialang.org/u/programista)\
**Replies:** 3\
**Last updated:** [September 22, 2020, 1:05pm UTC](https://discourse.julialang.org/t/whos-element-of-vector-y-is-in-set-x/47065 "2020-09-22T13:05:23Z")

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I have a long vectros of strings. How to do this fasastest ? julia\> x=\["a" "b"\] 1×2 Array{String,2}: "a" "b" julia\> x=\["a", "b"\] 2-element Array{String,1}: "a" "b" julia\> y=\["a","c","b","a","b"\] 5-element Array{St…

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## [Zero() and iszero() for mutable structs](https://discourse.julialang.org/t/zero-and-iszero-for-mutable-structs/46841)

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**Author:** [@efokken](https://discourse.julialang.org/u/efokken)\
**Replies:** 6\
**Last updated:** [September 22, 2020, 12:16pm UTC](https://discourse.julialang.org/t/zero-and-iszero-for-mutable-structs/46841 "2020-09-22T12:16:45Z")

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Hi there! It is useful for me to store a mutable struct Line in a sparse matrix. I had the impression that it is useful to define Base.zero(::Line) = Line(0,1,0) and Base.zero(::Type{Line}) = Line(0,1,0) unfortunat…

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## [Turn off warning from \`Mosek\` while using \`Convex.jl\`](https://discourse.julialang.org/t/turn-off-warning-from-mosek-while-using-convex-jl/47060)

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**Author:** [@iHany](https://discourse.julialang.org/u/iHany)\
**Replies:** 0\
**Last updated:** [September 22, 2020, 11:47am UTC](https://discourse.julialang.org/t/turn-off-warning-from-mosek-while-using-convex-jl/47060 "2020-09-22T11:47:39Z")

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Hi, I’m using Mosek as a solver of Convex.jl to solve convex problems. While solving problems, it quite often says warnings like MOSEK warning 705: #4 (nearly) zero elements are specified in sparse row ''(376) of matri…

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## [Intersection and union of polygons - IoU Metric](https://discourse.julialang.org/t/intersection-and-union-of-polygons-iou-metric/45506)

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**Author:** [@maxfreu](https://discourse.julialang.org/u/maxfreu)\
**Replies:** 2\
**Last updated:** [September 22, 2020, 11:47am UTC](https://discourse.julialang.org/t/intersection-and-union-of-polygons-iou-metric/45506 "2020-09-22T11:47:22Z")

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Hi! I would like to compute the intersection over union metric for polygons (concave polygons with holes). Is there a package which implements calculating the intersecting polygon, the union polygon as well as their are…

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## [Can the CuArray/CuPtr in CUDA.jl be directly passed to foreign functions?](https://discourse.julialang.org/t/can-the-cuarray-cuptr-in-cuda-jl-be-directly-passed-to-foreign-functions/46939)

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**Author:** [@weylspinor](https://discourse.julialang.org/u/weylspinor)\
**Replies:** 2\
**Last updated:** [September 22, 2020, 11:44am UTC](https://discourse.julialang.org/t/can-the-cuarray-cuptr-in-cuda-jl-be-directly-passed-to-foreign-functions/46939 "2020-09-22T11:44:10Z")

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Hi, I am just wondering if there is any way to directly pass CuArrays or CuPtr in CUDA.jl to C/C++, like passing Core.Array or Core.Ref. For example, I would like to define a C function which gets a device memory pointe…

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## [Dict's different behavior for using and include](https://discourse.julialang.org/t/dicts-different-behavior-for-using-and-include/47058)

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**Author:** [@N5N3](https://discourse.julialang.org/u/N5N3)\
**Replies:** 2\
**Last updated:** [September 22, 2020, 10:59am UTC](https://discourse.julialang.org/t/dicts-different-behavior-for-using-and-include/47058 "2020-09-22T10:59:26Z")

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First, I created a file named DictTest.jl with the following content: module DictTest data = Dict(GlobalRef(Base,:sum) =\> GlobalRef(Base,:prod), 1 =\> GlobalRef(Base,:sum)) end and put the file into the JULIA\_LOAD\_P…

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## [JuliaPro on Mac OS : issues with Plots](https://discourse.julialang.org/t/juliapro-on-mac-os-issues-with-plots/46960)

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**Author:** [@tbrochier](https://discourse.julialang.org/u/tbrochier)\
**Replies:** 3\
**Last updated:** [September 22, 2020, 9:09am UTC](https://discourse.julialang.org/t/juliapro-on-mac-os-issues-with-plots/46960 "2020-09-22T09:09:57Z")

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Hello, I recently installed JuliaPro on my mac (mac OS X 10.13.6) First, I downloaded the installation package " JuliaPro-1.5.1-1\_build-102.pkg » but I get an error message, “impossible to open”, so I downloaded the L…

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## [Modify FASTQ file description with a new string using FASTX](https://discourse.julialang.org/t/modify-fastq-file-description-with-a-new-string-using-fastx/46672)

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**Author:** [@Gopi1616](https://discourse.julialang.org/u/Gopi1616)\
**Replies:** 3\
**Last updated:** [September 22, 2020, 8:51am UTC](https://discourse.julialang.org/t/modify-fastq-file-description-with-a-new-string-using-fastx/46672 "2020-09-22T08:51:53Z")

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Hi, I am a python programmer and new to Julia. One of the tasks I am working on needs modification of description lines in Fastq sequence files. Doing this in python was pretty time-consuming. So wanted to try the same …

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## [Julia-vim and Indentation](https://discourse.julialang.org/t/julia-vim-and-indentation/47052)

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**Author:** [@iHany](https://discourse.julialang.org/u/iHany)\
**Replies:** 0\
**Last updated:** [September 22, 2020, 8:45am UTC](https://discourse.julialang.org/t/julia-vim-and-indentation/47052 "2020-09-22T08:45:43Z")

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I’m using vim and julia-vim. While editing julia files, I think that it supports weird indentation as follows: (Before pressing enter) a = (b + c) # cursor at before b (What I expected) a = ( b + c) (Result) …

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## [\`\] update Foo\` vs \`\] up Foo\`](https://discourse.julialang.org/t/update-foo-vs-up-foo/46738)

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**Author:** [@Samuel\_Ainsworth](https://discourse.julialang.org/u/Samuel_Ainsworth)\
**Replies:** 13\
**Last updated:** [September 22, 2020, 8:03am UTC](https://discourse.julialang.org/t/update-foo-vs-up-foo/46738 "2020-09-22T08:03:08Z")

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Ok, so I recently discovered – much to my surprise – that \] update Foo in fact updates all of the packages in my project. To update a single package you have to instead do \] up Foo. This is super, super confusing. I’ve b…

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## [Iterating n items at a time and filling](https://discourse.julialang.org/t/iterating-n-items-at-a-time-and-filling/47045)

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**Author:** [@mkitti](https://discourse.julialang.org/u/mkitti)\
**Replies:** 5\
**Last updated:** [September 22, 2020, 7:46am UTC](https://discourse.julialang.org/t/iterating-n-items-at-a-time-and-filling/47045 "2020-09-22T07:46:33Z")

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In Slack, @mastrof wanted the equivalent of the following Python 3 code which returns n items at a time and pads with fillvalue if there are less than n items remaining def f(iterable, n, fillvalue=None): args = \[it…

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## [Improving the code speed by employing parallelism for asynchronous task](https://discourse.julialang.org/t/improving-the-code-speed-by-employing-parallelism-for-asynchronous-task/47041)

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**Author:** [@Nova](https://discourse.julialang.org/u/Nova)\
**Replies:** 5\
**Last updated:** [September 22, 2020, 7:06am UTC](https://discourse.julialang.org/t/improving-the-code-speed-by-employing-parallelism-for-asynchronous-task/47041 "2020-09-22T07:06:01Z")

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I was trying to employ parallelism to improve the speed of the code using multi-threading. However, I noticed that I get wrong answer using multi-threading. The reason for that is my code update a value in a for loop con…

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## [Step by Step Documentation Tutorial](https://discourse.julialang.org/t/step-by-step-documentation-tutorial/46093)

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**Author:** [@SubhadityaMukherjee](https://discourse.julialang.org/u/SubhadityaMukherjee)\
**Replies:** 23\
**Last updated:** [September 22, 2020, 1:13am UTC](https://discourse.julialang.org/t/step-by-step-documentation-tutorial/46093 "2020-09-22T01:13:13Z")

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Did you just start making an amazing package and want to document it? Failing miserably? I was in your shoes a few days back and after a lot of drama I managed to get everything running. So I thought I would write a ste…

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## [Best strategy for fastest way to extract arrays built from matrix elements and then reassemble after ifft()](https://discourse.julialang.org/t/best-strategy-for-fastest-way-to-extract-arrays-built-from-matrix-elements-and-then-reassemble-after-ifft/46888)

<div class="topic-metadata">

**Author:** [@jleman](https://discourse.julialang.org/u/jleman)\
**Replies:** 0\
**Last updated:** [September 19, 2020, 1:48am UTC](https://discourse.julialang.org/t/best-strategy-for-fastest-way-to-extract-arrays-built-from-matrix-elements-and-then-reassemble-after-ifft/46888 "2020-09-19T01:48:47Z")

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I have a frequency domain data set organized as shown in the attached image (set up as an array of matrices like: \[zeros(40,4000) for \_ in 1:4096\] ) I need to create the time domain data set at right by applying the …

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## [Using Dualization](https://discourse.julialang.org/t/using-dualization/47036)

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**Author:** [@RaquelSantos](https://discourse.julialang.org/u/RaquelSantos)\
**Replies:** 1\
**Last updated:** [September 21, 2020, 8:40pm UTC](https://discourse.julialang.org/t/using-dualization/47036 "2020-09-21T20:40:54Z")

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I would like to pass this model to Dual but I still haven’t got it. Could someone help me? Thank you! using JuMP, Cbc, Dualization FabricaBrinquedos = Model(dual\_optimizer(Cbc.Optimizer))#When I try to compile using d…

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