# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1679

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

**Page:** 1680

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## [JuliaCon 2020 Mug](https://discourse.julialang.org/t/juliacon-2020-mug/43675)

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**Author:** [@logankilpatrick](https://discourse.julialang.org/u/logankilpatrick)\
**Replies:** 0\
**Last updated:** [July 25, 2020, 5:19pm UTC](https://discourse.julialang.org/t/juliacon-2020-mug/43675 "2020-07-25T17:19:37Z")

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Hey all, In case the JuliaCon 2020 T-shirt was not your thing, there is now a JuliaCon 2020 Mug available! -Logan on behalf of the JuliaCon organizing committee

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## [Variance and std of vectors](https://discourse.julialang.org/t/variance-and-std-of-vectors/43624)

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**Author:** [@aplavin](https://discourse.julialang.org/u/aplavin)\
**Replies:** 11\
**Last updated:** [July 25, 2020, 5:17pm UTC](https://discourse.julialang.org/t/variance-and-std-of-vectors/43624 "2020-07-25T17:17:53Z")

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In Julia Statistics module std() and var() work for arrays of numbers, including complex numbers - expectedly, they do not support arrays of vectors. However, it is often convenient to quantify the scatter of multiple ve…

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## [SOLVED: Joining discord fails](https://discourse.julialang.org/t/solved-joining-discord-fails/43668)

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**Author:** [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Replies:** 3\
**Last updated:** [July 25, 2020, 4:46pm UTC](https://discourse.julialang.org/t/solved-joining-discord-fails/43668 "2020-07-25T16:46:38Z")

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I tried to join discord, but it failed with “internal server error”. Perhaps I did not enter a valid registration ID? I used this number without the hash: Order #1381356530 - June 28, 2020 Perhaps I need to add the h…

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## [Do you git or hub](https://discourse.julialang.org/t/do-you-git-or-hub/43671)

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**Author:** [@tbeason](https://discourse.julialang.org/u/tbeason)\
**Replies:** 4\
**Last updated:** [July 25, 2020, 4:31pm UTC](https://discourse.julialang.org/t/do-you-git-or-hub/43671 "2020-07-25T16:31:20Z")

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Now that hub has been out a bit longer, I’m curious how many people make use of it versus just using the standard git cli (or something else). What is your preferred way to use GitHub? poll

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## [Unstack-stack-unstack-stack](https://discourse.julialang.org/t/unstack-stack-unstack-stack/43591)

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**Author:** [@victorialena](https://discourse.julialang.org/u/victorialena)\
**Replies:** 1\
**Last updated:** [July 25, 2020, 3:45pm UTC](https://discourse.julialang.org/t/unstack-stack-unstack-stack/43591 "2020-07-25T15:45:45Z")

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any ideas on how to make this more efficient? I don’t know how to broadcast the functions more efficiently than a for loop and matrix multiplications in 3D didn’t really work for me. Can someone help? # input has size …

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## [Why @view add a "true &&" before the view call?](https://discourse.julialang.org/t/why-view-add-a-true-before-the-view-call/43670)

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**Author:** [@N5N3](https://discourse.julialang.org/u/N5N3)\
**Replies:** 1\
**Last updated:** [July 25, 2020, 3:32pm UTC](https://discourse.julialang.org/t/why-view-add-a-true-before-the-view-call/43670 "2020-07-25T15:32:23Z")

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I’m try to look into the @avx macro offered by LoopVectorization.jl, which replace the Base.materialize(!) with the auther defined function. I want to use the same design to make my own module to support macro like @par…

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## [When does a package activation/instantiation trigger a build?](https://discourse.julialang.org/t/when-does-a-package-activation-instantiation-trigger-a-build/43649)

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**Author:** [@PetrKryslUCSD](https://discourse.julialang.org/u/PetrKryslUCSD)\
**Replies:** 3\
**Last updated:** [July 25, 2020, 3:17pm UTC](https://discourse.julialang.org/t/when-does-a-package-activation-instantiation-trigger-a-build/43649 "2020-07-25T15:17:48Z")

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When is a build triggered for a package that has a deps/build.jl? It is not triggered when I do activate/instantiate. Is there an automatic build? Or is an explicit build() required?

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## [Mechanism for build() in mybinder?](https://discourse.julialang.org/t/mechanism-for-build-in-mybinder/43644)

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**Author:** [@PetrKryslUCSD](https://discourse.julialang.org/u/PetrKryslUCSD)\
**Replies:** 1\
**Last updated:** [July 25, 2020, 2:50am UTC](https://discourse.julialang.org/t/mechanism-for-build-in-mybinder/43644 "2020-07-25T02:50:11Z")

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I have a package of tutorials. I can use the package locally by using Pkg; Pkg.activate("."); Pkg.instantiate() Pkg.build() This builds the tutorial notebooks. How do I get these notebooks built on mybinder?

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## [\[ANN\] ReadableRegex.jl](https://discourse.julialang.org/t/ann-readableregex-jl/43450)

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**Author:** [@jules](https://discourse.julialang.org/u/jules)\
**Replies:** 8\
**Last updated:** [July 25, 2020, 1:04pm UTC](https://discourse.julialang.org/t/ann-readableregex-jl/43450 "2020-07-25T13:04:31Z")

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Hi everyone, As it randomly came up on Slack today, I might as well announce a small new package here: ReadableRegex.jl GitHub - jkrumbiegel/ReadableRegex.jl: regexes for people who don't really want to learn or read re…

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## [A nifty trick to run Julia in Kaggle](https://discourse.julialang.org/t/a-nifty-trick-to-run-julia-in-kaggle/43664)

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**Author:** [@themadprogramer](https://discourse.julialang.org/u/themadprogramer)\
**Replies:** 0\
**Last updated:** [July 25, 2020, 12:44pm UTC](https://discourse.julialang.org/t/a-nifty-trick-to-run-julia-in-kaggle/43664 "2020-07-25T12:44:16Z")

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So I have been waiting for native support on Kaggle for Julia, as of many of you here for a few months now. Although there actually is, a hacky way to use Julia on Kaggle. With some python magic and environment shenanig…

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## [Function methods based solely on element type of array of arbitrary dimension](https://discourse.julialang.org/t/function-methods-based-solely-on-element-type-of-array-of-arbitrary-dimension/43653)

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**Author:** [@jerjorg](https://discourse.julialang.org/u/jerjorg)\
**Replies:** 6\
**Last updated:** [July 25, 2020, 12:10pm UTC](https://discourse.julialang.org/t/function-methods-based-solely-on-element-type-of-array-of-arbitrary-dimension/43653 "2020-07-25T12:10:11Z")

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I’m new to Julia, so my question may be naive or obvious. I’ve searched the documentation and elsewhere but can’t find an answer. Is it possible to define a function in Julia that takes as an argument an array of arbitra…

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## [\[RFC\] JuliaCon2020Workshops.jl](https://discourse.julialang.org/t/rfc-juliacon2020workshops-jl/43662)

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**Author:** [@cserteGT3](https://discourse.julialang.org/u/cserteGT3)\
**Replies:** 0\
**Last updated:** [July 25, 2020, 12:01pm UTC](https://discourse.julialang.org/t/rfc-juliacon2020workshops-jl/43662 "2020-07-25T12:01:46Z")

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Based on a slack discussion, I’ve put together a small package: JuliaCon2020Workshops.jl, that pulls the workshop repos and starts a jupyter notebook. It may help beginners to easily start working (just install julia and…

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## [Make Pkg.undo work accross sessions](https://discourse.julialang.org/t/make-pkg-undo-work-accross-sessions/43630)

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**Author:** [@NightMachinary](https://discourse.julialang.org/u/NightMachinary)\
**Replies:** 2\
**Last updated:** [July 25, 2020, 7:53am UTC](https://discourse.julialang.org/t/make-pkg-undo-work-accross-sessions/43630 "2020-07-25T07:53:15Z")

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I use this shell function to easily install Julia packages: jins () { julia --startup-file=no -e 'using Pkg; Pkg.add("'"$1"'"); Pkg.precompile()' } So when something goes wrong, I can’t use Pkg.undo() and get: ERR…

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## [Kwargs in new(), or safer ways of constructing immutable structs](https://discourse.julialang.org/t/kwargs-in-new-or-safer-ways-of-constructing-immutable-structs/43555)

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**Author:** [@Benjia](https://discourse.julialang.org/u/Benjia)\
**Replies:** 11\
**Last updated:** [July 25, 2020, 7:01am UTC](https://discourse.julialang.org/t/kwargs-in-new-or-safer-ways-of-constructing-immutable-structs/43555 "2020-07-25T07:01:22Z")

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When creating an immutable struct with a reasonable number of fields and an inner constructor, I find that aligning the arguments to new() with the order of the struct fields to be quite tedious and error prone (especial…

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## [One-pass NaN variance](https://discourse.julialang.org/t/one-pass-nan-variance/43622)

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**Author:** [@Benjia](https://discourse.julialang.org/u/Benjia)\
**Replies:** 3\
**Last updated:** [July 25, 2020, 4:36am UTC](https://discourse.julialang.org/t/one-pass-nan-variance/43622 "2020-07-25T04:36:37Z")

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I’d like to try and use the implementation of Welford’s algorithm in Base.Statistics, but filter out NaNs along the way. First thing I tried is the following: Statistics.var(Iterators.filter(!isnan, vals)) However, th…

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## [To Adopt mandatory semicolon in method calls if kwargs are passed](https://discourse.julialang.org/t/to-adopt-mandatory-semicolon-in-method-calls-if-kwargs-are-passed/43651)

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**Author:** [@josePereiro](https://discourse.julialang.org/u/josePereiro)\
**Replies:** 7\
**Last updated:** [July 25, 2020, 4:11am UTC](https://discourse.julialang.org/t/to-adopt-mandatory-semicolon-in-method-calls-if-kwargs-are-passed/43651 "2020-07-25T04:11:50Z")

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Hi, I make semicolon keys for living and I just wanna extend my market beyond C-like languages. Author Note: Initial joke for relaxing angry people because of the title A good and clear interpretation of semicolon in …

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## [Is there a way to reinterpret a Float64 to 2 Int32?](https://discourse.julialang.org/t/is-there-a-way-to-reinterpret-a-float64-to-2-int32/43596)

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**Author:** [@Oscar\_Smith](https://discourse.julialang.org/u/Oscar_Smith)\
**Replies:** 3\
**Last updated:** [July 24, 2020, 11:24pm UTC](https://discourse.julialang.org/t/is-there-a-way-to-reinterpret-a-float64-to-2-int32/43596 "2020-07-24T23:24:46Z")

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I’m writing some manually vectorize some code (for computing exp), and I was looking for a way to view the memory as 2 int32s (if it helps, I only need the lower one). Is there a way to do this? The reason I want Int32 r…

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## [Building some Data analysis Tutorials](https://discourse.julialang.org/t/building-some-data-analysis-tutorials/40455)

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**Author:** [@dlakelan](https://discourse.julialang.org/u/dlakelan)\
**Replies:** 35\
**Last updated:** [July 24, 2020, 11:46pm UTC](https://discourse.julialang.org/t/building-some-data-analysis-tutorials/40455 "2020-07-24T23:46:44Z")

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For several years I’ve wanted to jump into Julia. I tried last summer but wound up with no time because my wife was teaching a course and I had the kids full time. Now I have got a couple projects where I’m using Julia a…

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## [Resolve GlobalRef in a generated function](https://discourse.julialang.org/t/resolve-globalref-in-a-generated-function/43645)

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**Author:** [@dfdx](https://discourse.julialang.org/u/dfdx)\
**Replies:** 2\
**Last updated:** [July 24, 2020, 11:45pm UTC](https://discourse.julialang.org/t/resolve-globalref-in-a-generated-function/43645 "2020-07-24T23:45:46Z")

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I’m using @dynamo from IRTools to rewrite all calls inside a passed function. There is a set of functions - let’s call them primitives - that I don’t want to rewrite, and thus I need to check if a particular function is …

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## [Correct use of the sparsity pattern in NLsolve.jl for Diagonal Jacobians](https://discourse.julialang.org/t/correct-use-of-the-sparsity-pattern-in-nlsolve-jl-for-diagonal-jacobians/43469)

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**Author:** [@mleprovost](https://discourse.julialang.org/u/mleprovost)\
**Replies:** 6\
**Last updated:** [July 24, 2020, 11:34pm UTC](https://discourse.julialang.org/t/correct-use-of-the-sparsity-pattern-in-nlsolve-jl-for-diagonal-jacobians/43469 "2020-07-24T23:34:01Z")

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Hello, I would like to solve \\sim 400 nonlinear equations using NLsolve.jl for which the Jacobian matrix is diagonal, i.e. the components are independent of each other. I would like to use the sparsity pattern to sp…

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## [Polynomials.fit causing LinearAlgebra.LAPACKException error on 1 computer](https://discourse.julialang.org/t/polynomials-fit-causing-linearalgebra-lapackexception-error-on-1-computer/43594)

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**Author:** [@Zhong\_Pan](https://discourse.julialang.org/u/Zhong_Pan)\
**Replies:** 1\
**Last updated:** [July 24, 2020, 10:58pm UTC](https://discourse.julialang.org/t/polynomials-fit-causing-linearalgebra-lapackexception-error-on-1-computer/43594 "2020-07-24T22:58:56Z")

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A very strange problem I met that I can reproduce every time with the original code, but I am not able to create a minimal example to reproduce it. Hence I am posting here to see if anybody has seen something similar ins…

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## [Get rid of a grid behind the text in Makie](https://discourse.julialang.org/t/get-rid-of-a-grid-behind-the-text-in-makie/43641)

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**Author:** [@pauljurczak](https://discourse.julialang.org/u/pauljurczak)\
**Replies:** 1\
**Last updated:** [July 24, 2020, 10:28pm UTC](https://discourse.julialang.org/t/get-rid-of-a-grid-behind-the-text-in-makie/43641 "2020-07-24T22:28:29Z")

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Running this snippet: using Makie, Random scene = Scene(resolution = (1200, 1500)) scene1 = Scene(scene, IRect(0, 0, 1200, 900)) image = rand(1:4, 640, 480) imagenode = Node(image) image!(scene1, imagenode, scale\_plot…

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## [ChainRules rrule for a fairly simple function](https://discourse.julialang.org/t/chainrules-rrule-for-a-fairly-simple-function/43593)

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**Author:** [@omalled](https://discourse.julialang.org/u/omalled)\
**Replies:** 2\
**Last updated:** [July 24, 2020, 10:02pm UTC](https://discourse.julialang.org/t/chainrules-rrule-for-a-fairly-simple-function/43593 "2020-07-24T22:02:44Z")

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I have some code that roughly follows this pattern where a function g iteratively calls a function f, stores the results in an array where the input to the next call to f involves the output of the last call to f, and re…

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## [Expressing a week before the time right now](https://discourse.julialang.org/t/expressing-a-week-before-the-time-right-now/43633)

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**Author:** [@Nash](https://discourse.julialang.org/u/Nash)\
**Replies:** 1\
**Last updated:** [July 24, 2020, 8:13pm UTC](https://discourse.julialang.org/t/expressing-a-week-before-the-time-right-now/43633 "2020-07-24T20:13:46Z")

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Suppose I express the time right now as: rightnow = Dates.format(Dates.now(Dates.UTC),"Y-mm-ddTH:MM:SS.SSSZ") Now I need to express, in the same format, the time at some previous point, say, one week from rightnow. How…

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## [Memory allocation in broadcast assignment](https://discourse.julialang.org/t/memory-allocation-in-broadcast-assignment/43613)

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**Author:** [@serenity4](https://discourse.julialang.org/u/serenity4)\
**Replies:** 3\
**Last updated:** [July 24, 2020, 8:05pm UTC](https://discourse.julialang.org/t/memory-allocation-in-broadcast-assignment/43613 "2020-07-24T20:05:33Z")

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Hi! I am struggling to keep a certain level of flexibility and abstraction while optimizing for performance. For example, in the following function, I am doing some processing and modify an array arr in-place. arr = zer…

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## [Avoiding type instabilities (with StaticKernels)](https://discourse.julialang.org/t/avoiding-type-instabilities-with-statickernels/43574)

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**Author:** [@tbeason](https://discourse.julialang.org/u/tbeason)\
**Replies:** 3\
**Last updated:** [July 24, 2020, 7:24pm UTC](https://discourse.julialang.org/t/avoiding-type-instabilities-with-statickernels/43574 "2020-07-24T19:24:38Z")

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I am trying to construct a Kernel from StaticKernels.jl dynamically. I would like to pass the window range and the function to apply as variables. The problem is that the axes of the Kernel are a part of the type informa…

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## [\[ANN\] Announcing CGAL.jl](https://discourse.julialang.org/t/ann-announcing-cgal-jl/43260)

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**Author:** [@rgcv](https://discourse.julialang.org/u/rgcv)\
**Replies:** 8\
**Last updated:** [July 24, 2020, 5:46pm UTC](https://discourse.julialang.org/t/ann-announcing-cgal-jl/43260 "2020-07-24T17:46:54Z")

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Good evening, I’m pleased to announce that I’ve just registered CGAL.jl, a package that aptly maps a series of types and functionality from CGAL (Computational Geometry Algorithms Library), a C++ library, to Julia. I’v…

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## [How can I implement positive Domain for sundials CVODE\_BDF ? Also, try to compare both isoutofdomain , with julia solvers, one question there, Thanks](https://discourse.julialang.org/t/how-can-i-implement-positive-domain-for-sundials-cvode-bdf-also-try-to-compare-both-isoutofdomain-with-julia-solvers-one-question-there-thanks/43390)

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**Author:** [@cbasile21](https://discourse.julialang.org/u/cbasile21)\
**Replies:** 4\
**Last updated:** [July 24, 2020, 5:40pm UTC](https://discourse.julialang.org/t/how-can-i-implement-positive-domain-for-sundials-cvode-bdf-also-try-to-compare-both-isoutofdomain-with-julia-solvers-one-question-there-thanks/43390 "2020-07-24T17:40:00Z")

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On the below problem, I had two questions When applying kencarp4 isoutofdomain is being applied to both states rather than the second du2 like I want to , so the IC is being populated for both states, but I expect onl…

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## [Best practices in dealing avoiding with precision/floating round of problems when solving ODE's? Thank you](https://discourse.julialang.org/t/best-practices-in-dealing-avoiding-with-precision-floating-round-of-problems-when-solving-odes-thank-you/43394)

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**Author:** [@cbasile21](https://discourse.julialang.org/u/cbasile21)\
**Replies:** 2\
**Last updated:** [July 24, 2020, 5:31pm UTC](https://discourse.julialang.org/t/best-practices-in-dealing-avoiding-with-precision-floating-round-of-problems-when-solving-odes-thank-you/43394 "2020-07-24T17:31:40Z")

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Here is an extreme case I posed. Here, I end up with a domain error, because I start at 0.1 ( any higher ) one parameter will give a domain error, I chose du\[2\] to be 0 or close to it with a negative value. I get a domai…

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## [\#count JOSS reviewer by lang and their sectors](https://discourse.julialang.org/t/count-joss-reviewer-by-lang-and-their-sectors/43614)

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**Author:** [@sylvaticus](https://discourse.julialang.org/u/sylvaticus)\
**Replies:** 2\
**Last updated:** [July 24, 2020, 4:32pm UTC](https://discourse.julialang.org/t/count-joss-reviewer-by-lang-and-their-sectors/43614 "2020-07-24T16:32:37Z")

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I was curious about which languages programmers-researchers in academic were using, so I went on the public list of reviewers of the Journal of Open Source Software (JOSS) available here and grab the data. Here the resu…

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