# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1254

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

**Page:** 1255

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## [Arithmetic using binary numbers](https://discourse.julialang.org/t/arithmetic-using-binary-numbers/68823)

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**Author:** [@Jaidy](https://discourse.julialang.org/u/Jaidy)\
**Replies:** 7\
**Last updated:** [September 27, 2021, 10:19pm UTC](https://discourse.julialang.org/t/arithmetic-using-binary-numbers/68823 "2021-09-27T22:19:15Z")

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I have huge matrices each entry of which is a 2-bit binary number. If I were to load them and convert to any of the Floats precisions, the memory required to load will be at least half a terabyte. Can Julia do arithmetic…

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## [Using AbstractEnv from CommonRLInterface with POMDPs](https://discourse.julialang.org/t/using-abstractenv-from-commonrlinterface-with-pomdps/68730)

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**Author:** [@Tyler\_Ingebrand](https://discourse.julialang.org/u/Tyler_Ingebrand)\
**Replies:** 22\
**Last updated:** [September 27, 2021, 9:47pm UTC](https://discourse.julialang.org/t/using-abstractenv-from-commonrlinterface-with-pomdps/68730 "2021-09-27T21:47:06Z")

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Hello. I am trying to use reinforcement learning to solve a simple problem as a proof of concept. I am using DeepQLearning and defining the AbstractEnv(an interface from CommonRLInterface). I am getting the following err…

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## [Problem using JuMP with user-defined function](https://discourse.julialang.org/t/problem-using-jump-with-user-defined-function/68835)

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**Author:** [@vinicius\_de\_lima](https://discourse.julialang.org/u/vinicius_de_lima)\
**Replies:** 1\
**Last updated:** [September 27, 2021, 9:40pm UTC](https://discourse.julialang.org/t/problem-using-jump-with-user-defined-function/68835 "2021-09-27T21:40:48Z")

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I am trying to use JuMP to solve a Non-linear optimization problem, but find a problem using the following code: function Q(H,h\_0,C,D,L) if H \<= h\_0 return 0.0 else Δh = H - h\_0 J = …

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## [How to install CO2System.jl package](https://discourse.julialang.org/t/how-to-install-co2system-jl-package/68817)

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**Author:** [@leon](https://discourse.julialang.org/u/leon)\
**Replies:** 2\
**Last updated:** [September 27, 2021, 9:39pm UTC](https://discourse.julialang.org/t/how-to-install-co2system-jl-package/68817 "2021-09-27T21:39:17Z")

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The package is located here: https://github.com/mvdh7/CO2System.jl. According to the installation instructions, I should install the CO2System package as below: pkg\> add https://github.com/mvdh7/CO2System.jl My questi…

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## [Using a closure with mutable captured values inside an @distributed loop](https://discourse.julialang.org/t/using-a-closure-with-mutable-captured-values-inside-an-distributed-loop/68818)

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**Author:** [@CameronBieganek](https://discourse.julialang.org/u/CameronBieganek)\
**Replies:** 2\
**Last updated:** [September 27, 2021, 9:02pm UTC](https://discourse.julialang.org/t/using-a-closure-with-mutable-captured-values-inside-an-distributed-loop/68818 "2021-09-27T21:02:59Z")

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The Julia manual says the following about the @distributed macro: Any variables used inside the parallel loop will be copied and broadcast to each process. My question is: Does this also apply to functions and closur…

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## [Array of hourly dates](https://discourse.julialang.org/t/array-of-hourly-dates/68827)

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**Author:** [@Mariana](https://discourse.julialang.org/u/Mariana)\
**Replies:** 2\
**Last updated:** [September 27, 2021, 7:19pm UTC](https://discourse.julialang.org/t/array-of-hourly-dates/68827 "2021-09-27T19:19:38Z")

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Hello! I’m trying to use the package Dates to create an array of dates, with the granularity of one hour. For example, I’d like to create an array with all the hours from January 10 to January 20. Any ideas on how I can…

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## [Reading in multiple matrices of different dimensions from .txt file](https://discourse.julialang.org/t/reading-in-multiple-matrices-of-different-dimensions-from-txt-file/68796)

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**Author:** [@conorhassan](https://discourse.julialang.org/u/conorhassan)\
**Replies:** 6\
**Last updated:** [September 27, 2021, 7:05pm UTC](https://discourse.julialang.org/t/reading-in-multiple-matrices-of-different-dimensions-from-txt-file/68796 "2021-09-27T19:05:47Z")

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Hi all, I have a .txt file containing information for 10 matrices of different dimensions. Each row of the .txt file corresponds to a row of a matrix, with whitespace distinguishing the elements. The matrices are seper…

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## [Using inconsistency between Pluto and REPL with dev Package](https://discourse.julialang.org/t/using-inconsistency-between-pluto-and-repl-with-dev-package/68828)

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**Author:** [@Jake](https://discourse.julialang.org/u/Jake)\
**Replies:** 1\
**Last updated:** [September 27, 2021, 7:04pm UTC](https://discourse.julialang.org/t/using-inconsistency-between-pluto-and-repl-with-dev-package/68828 "2021-09-27T19:04:55Z")

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I have a Package “Foo” I have developed in .julia\\dev. I just updated to Julia version 1.6.3 in Win10. When I updated to 1.6.3 I updated the package “\] update Foo” and then in the REPL when I type ‘using Foo’ the comma…

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## [Symbolics.jl: Speed of derivative computations vs. SymEngine.jl](https://discourse.julialang.org/t/symbolics-jl-speed-of-derivative-computations-vs-symengine-jl/68803)

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**Author:** [@ranocha](https://discourse.julialang.org/u/ranocha)\
**Replies:** 2\
**Last updated:** [September 27, 2021, 6:24pm UTC](https://discourse.julialang.org/t/symbolics-jl-speed-of-derivative-computations-vs-symengine-jl/68803 "2021-09-27T18:24:24Z")

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I benchmarked some derivative computations using Symbolics.jl, SymEngine.jl, and SymPy.jl. As expected, SymPy.jl was the slowest solution in my case. However, SymEngine.jl was significantly faster than Symbolics.jl. Here…

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## [How to retrieve the edge list from a Dict reprepresenting a tree data structure](https://discourse.julialang.org/t/how-to-retrieve-the-edge-list-from-a-dict-reprepresenting-a-tree-data-structure/68802)

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**Author:** [@empet](https://discourse.julialang.org/u/empet)\
**Replies:** 6\
**Last updated:** [September 27, 2021, 5:56pm UTC](https://discourse.julialang.org/t/how-to-retrieve-the-edge-list-from-a-dict-reprepresenting-a-tree-data-structure/68802 "2021-09-27T17:56:29Z")

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I’m reading a tree data structure fron a json file, and I need to retrieve the vector of edge tuples, (parent, child), to define a LightGraphs.SimpleDiGraph and get the node positions via NetworkLayout.Buchheim layou…

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## [Iterate through all combinations of elements in an arbitrary number of arrays](https://discourse.julialang.org/t/iterate-through-all-combinations-of-elements-in-an-arbitrary-number-of-arrays/68819)

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**Author:** [@Torkel](https://discourse.julialang.org/u/Torkel)\
**Replies:** 2\
**Last updated:** [September 27, 2021, 4:53pm UTC](https://discourse.julialang.org/t/iterate-through-all-combinations-of-elements-in-an-arbitrary-number-of-arrays/68819 "2021-09-27T16:53:29Z")

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I have an array arrays which contains a number of arrays (arbitrary). How do I iterate through all combinations of elelements? If I know that there are e.g. 3 arrays I can do: for e1 in arrays\[1\], e2 in arrays\[2\], e3 i…

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## [Help for the lazy](https://discourse.julialang.org/t/help-for-the-lazy/68801)

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**Author:** [@amrods](https://discourse.julialang.org/u/amrods)\
**Replies:** 2\
**Last updated:** [September 27, 2021, 3:33pm UTC](https://discourse.julialang.org/t/help-for-the-lazy/68801 "2021-09-27T15:33:26Z")

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I have several matrices x1, ..., xn what’s a way to create a named tuple (x1=x1, ..., xn=xn) without having to type all components one by one? For example: x1 = rand(2, 2) x2 = rand(2, 2) x3 = rand(2, 2) lazyhelper(x1…

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## ['Package' depends on 'Dependency', but no such entry exists in the manifest](https://discourse.julialang.org/t/package-depends-on-dependency-but-no-such-entry-exists-in-the-manifest/68808)

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**Author:** [@thompsonmj](https://discourse.julialang.org/u/thompsonmj)\
**Replies:** 2\
**Last updated:** [September 27, 2021, 2:15pm UTC](https://discourse.julialang.org/t/package-depends-on-dependency-but-no-such-entry-exists-in-the-manifest/68808 "2021-09-27T14:15:50Z")

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This seems to have become an issue randomly over the weekend. I try to activate an environment and am met with: ERROR: \`ModelingToolkit=961ee093-0014-501f-94e3-6117800e7a78\` depends on \`SafeTestsets\`, but no such entry …

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## [How to change Gtk predefined widgets?](https://discourse.julialang.org/t/how-to-change-gtk-predefined-widgets/68812)

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**Author:** [@mathdeep](https://discourse.julialang.org/u/mathdeep)\
**Replies:** 0\
**Last updated:** [September 27, 2021, 2:14pm UTC](https://discourse.julialang.org/t/how-to-change-gtk-predefined-widgets/68812 "2021-09-27T14:14:20Z")

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Hi there, I’m trying to build a little help for a friend and therefor would like to have a small UI. What I want to do: The user should be able to select files (maybe drag and drop them if I have the time and am not to…

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## [Need a combinatorial optimizer for black box function](https://discourse.julialang.org/t/need-a-combinatorial-optimizer-for-black-box-function/68791)

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**Author:** [@PeterSimon](https://discourse.julialang.org/u/PeterSimon)\
**Replies:** 6\
**Last updated:** [September 27, 2021, 1:34pm UTC](https://discourse.julialang.org/t/need-a-combinatorial-optimizer-for-black-box-function/68791 "2021-09-27T13:34:03Z")

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I’m looking for a combinatorial optimizer (decision variables are a permutation of the integers 1, 2, \\ldots, N, where N is between, say, 50, and 500, for a black box function (i.e., only the value of the objective funct…

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## [Research Engineer - Distributed simulation](https://discourse.julialang.org/t/research-engineer-distributed-simulation/68804)

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**Author:** [@johnh](https://discourse.julialang.org/u/johnh)\
**Replies:** 0\
**Last updated:** [September 27, 2021, 12:16pm UTC](https://discourse.julialang.org/t/research-engineer-distributed-simulation/68804 "2021-09-27T12:16:39Z")

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I do not know this company. Mentions Python etc but not Julia specifically https://www.linkedin.com/jobs/view/2683210649/

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## [Has anyone used julia to work with the Notion api?](https://discourse.julialang.org/t/has-anyone-used-julia-to-work-with-the-notion-api/68741)

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**Author:** [@development\_mentor](https://discourse.julialang.org/u/development_mentor)\
**Replies:** 1\
**Last updated:** [September 27, 2021, 10:59am UTC](https://discourse.julialang.org/t/has-anyone-used-julia-to-work-with-the-notion-api/68741 "2021-09-27T10:59:11Z")

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I want to use Julia to build a notion API in order to create some custom functions that aren’t originally in notion. I’m new to APIs and don’t know if it’s possible to use an API with any language.

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## [Send multipart request from julia using HTTP.jl](https://discourse.julialang.org/t/send-multipart-request-from-julia-using-http-jl/60148)

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**Author:** [@Michal](https://discourse.julialang.org/u/Michal)\
**Replies:** 8\
**Last updated:** [September 27, 2021, 8:08am UTC](https://discourse.julialang.org/t/send-multipart-request-from-julia-using-http-jl/60148 "2021-09-27T08:08:26Z")

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How can I send multipart request using HTTP.jl where first part is json ans seocnd is csv file? HTTP.request("POST"...

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## [Find frequent words](https://discourse.julialang.org/t/find-frequent-words/68790)

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**Author:** [@IsraelSI](https://discourse.julialang.org/u/IsraelSI)\
**Replies:** 3\
**Last updated:** [September 27, 2021, 6:19am UTC](https://discourse.julialang.org/t/find-frequent-words/68790 "2021-09-27T06:19:47Z")

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Hello colleagues, I have recently learned Julia based on the book “Getting Started with Julia” and in it there is an example of finding frequent words in a text: # code in chapter 5\\word\_frequency.jl: # 1- read in text …

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## [Agent-based model performance](https://discourse.julialang.org/t/agent-based-model-performance/68758)

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**Author:** [@Peter\_Uhl](https://discourse.julialang.org/u/Peter_Uhl)\
**Replies:** 14\
**Last updated:** [September 27, 2021, 5:39am UTC](https://discourse.julialang.org/t/agent-based-model-performance/68758 "2021-09-27T05:39:14Z")

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Hi all, I am working to improve the performance of an agent-based model. The model is of two bacterial species whose growth and death probabilities are determined by the amount of a nutrient available locally. I’m aware…

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## [How to redirect to "nothing" the standard output of a function I call?](https://discourse.julialang.org/t/how-to-redirect-to-nothing-the-standard-output-of-a-function-i-call/49106)

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**Author:** [@sylvaticus](https://discourse.julialang.org/u/sylvaticus)\
**Replies:** 4\
**Last updated:** [September 27, 2021, 3:09am UTC](https://discourse.julialang.org/t/how-to-redirect-to-nothing-the-standard-output-of-a-function-i-call/49106 "2021-09-27T03:09:54Z")

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I have a function that prints some stuff I don’t need (the IPOPT licence… the problem is that this is in a long loop…). How do I specify, when I call function foo() that I want its standard output stream to be redirecte…

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## [Creating a Julia Animations Organization on GitHub](https://discourse.julialang.org/t/creating-a-julia-animations-organization-on-github/68783)

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**Author:** [@TheCedarPrince](https://discourse.julialang.org/u/TheCedarPrince)\
**Replies:** 3\
**Last updated:** [September 27, 2021, 2:34am UTC](https://discourse.julialang.org/t/creating-a-julia-animations-organization-on-github/68783 "2021-09-27T02:34:58Z")

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Hey all, @Wikunia and I are looking to create a GitHub organization to house Javis.jl and associated animation tools in the Julia ecosystem. Would it be in good taste if we created a GitHub organization called, “Julia A…

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## [Get post attributes in Franklin](https://discourse.julialang.org/t/get-post-attributes-in-franklin/68430)

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**Author:** [@garrek](https://discourse.julialang.org/u/garrek)\
**Replies:** 12\
**Last updated:** [September 27, 2021, 1:49am UTC](https://discourse.julialang.org/t/get-post-attributes-in-franklin/68430 "2021-09-27T01:49:33Z")

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I’m in the process of migrating from Jekyll to Franklin for my static website (Garrek.org) hosted on GitHub. (In the near future, I will have LaTeX and plots and things, which Franklin seems to excel at). Jekyll has some…

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## [How to specify algorithm-specific parameters in NLopt.jl?](https://discourse.julialang.org/t/how-to-specify-algorithm-specific-parameters-in-nlopt-jl/68765)

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**Author:** [@amrods](https://discourse.julialang.org/u/amrods)\
**Replies:** 7\
**Last updated:** [September 27, 2021, 1:44am UTC](https://discourse.julialang.org/t/how-to-specify-algorithm-specific-parameters-in-nlopt-jl/68765 "2021-09-27T01:44:47Z")

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The General Reference of NLopt here describes how to specify algorithm-specific parameters, but the NLopt.jl documentation does not have that section. Is it possible to access those parameters from NLopt.jl?

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## [How to modify a JSON object that's been read in?](https://discourse.julialang.org/t/how-to-modify-a-json-object-thats-been-read-in/68775)

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**Author:** [@xiaodai](https://discourse.julialang.org/u/xiaodai)\
**Replies:** 2\
**Last updated:** [September 27, 2021, 1:04am UTC](https://discourse.julialang.org/t/how-to-modify-a-json-object-thats-been-read-in/68775 "2021-09-27T01:04:45Z")

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I have read a JSON using JSON3.jl but after that I can’t seem to modify the json. E.g. a = JSON3.read("{\\"a\\":1}") a\[:b\] = 2 what I get is this. Is there an easy to mutate the object? LoadError: MethodError: no met…

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## [Best way for a task to read from two channels](https://discourse.julialang.org/t/best-way-for-a-task-to-read-from-two-channels/68704)

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**Author:** [@adriano.vilela](https://discourse.julialang.org/u/adriano.vilela)\
**Replies:** 25\
**Last updated:** [September 27, 2021, 12:48am UTC](https://discourse.julialang.org/t/best-way-for-a-task-to-read-from-two-channels/68704 "2021-09-27T00:48:30Z")

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Hi, I’m working on a problem that involves tasks communicating through channels. I have a task that needs to read from two channels and I’m trying to figure out the best way of doing that. The task needs to read an in…

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## [Julia 1.6.3 pdf version of documentation missing](https://discourse.julialang.org/t/julia-1-6-3-pdf-version-of-documentation-missing/68760)

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**Author:** [@murrayE](https://discourse.julialang.org/u/murrayE)\
**Replies:** 1\
**Last updated:** [September 26, 2021, 10:51pm UTC](https://discourse.julialang.org/t/julia-1-6-3-pdf-version-of-documentation-missing/68760 "2021-09-26T22:51:54Z")

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The link at Julia Documentation · The Julia Language to the PDF version of Julia 1.6.3 documentation gives a “404 not found” error.

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## [\[ANN\] RemoteS.jl](https://discourse.julialang.org/t/ann-remotes-jl/68782)

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**Author:** [@joa-quim](https://discourse.julialang.org/u/joa-quim)\
**Replies:** 3\
**Last updated:** [September 26, 2021, 9:45pm UTC](https://discourse.julialang.org/t/ann-remotes-jl/68782 "2021-09-26T21:45:53Z")

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Hi, I’m pleased to announce the RemoteS.jl package to deal mainly with EOS satellite data. See examples in the Gallery to get the feeling of this package Plot AQUA satellite tracks. @Ronis\_BR this one is for you …

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## [Sum of doubles](https://discourse.julialang.org/t/sum-of-doubles/68747)

<div class="topic-metadata">

**Author:** [@HexxCube](https://discourse.julialang.org/u/HexxCube)\
**Replies:** 16\
**Last updated:** [September 26, 2021, 9:02pm UTC](https://discourse.julialang.org/t/sum-of-doubles/68747 "2021-09-26T21:02:55Z")

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I am trying to speed up my solution to the following exercise: Given a Array of int values (from 1 to p), return the sum of doubles. If one of the values occurs only once, it does not count towards the sum. loneSum(\[1…

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## [Why is this @tullio example failing with a range error?](https://discourse.julialang.org/t/why-is-this-tullio-example-failing-with-a-range-error/68748)

<div class="topic-metadata">

**Author:** [@Chiil](https://discourse.julialang.org/u/Chiil)\
**Replies:** 2\
**Last updated:** [September 26, 2021, 7:52pm UTC](https://discourse.julialang.org/t/why-is-this-tullio-example-failing-with-a-range-error/68748 "2021-09-26T19:52:25Z")

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I am experimenting with Tullio in order to write fast nested loops. I have arrays on which I perform computations on a subset. I do not know why this is failing, as all indices get a range provided. using Tullio itot =…

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