# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1472

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

**Page:** 1473

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## [LoadError: MethodError: no method matching record although another package with "record" works](https://discourse.julialang.org/t/loaderror-methoderror-no-method-matching-record-although-another-package-with-record-works/56394)

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**Author:** [@meck](https://discourse.julialang.org/u/meck)\
**Replies:** 0\
**Last updated:** [March 3, 2021, 9:55am UTC](https://discourse.julialang.org/t/loaderror-methoderror-no-method-matching-record-although-another-package-with-record-works/56394 "2021-03-03T09:55:03Z")

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First package using WaterLily using LinearAlgebra: norm2 using Makie function donut\_sim(p=6,Re=1e3) # Define simulation size, velocity, viscosity n,U = 2^p, \[1, 0, 0\] center,R,r = \[n/2,n/2,n/2\], n/4, n/16 …

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## [Symmetric matrix operations not faster](https://discourse.julialang.org/t/symmetric-matrix-operations-not-faster/56250)

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**Author:** [@Xijiang\_Yu](https://discourse.julialang.org/u/Xijiang_Yu)\
**Replies:** 6\
**Last updated:** [March 3, 2021, 9:32am UTC](https://discourse.julialang.org/t/symmetric-matrix-operations-not-faster/56250 "2021-03-03T09:32:33Z")

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I was expecting that if a matrix is defined symmetric, some operations, e.g., solving, should be faster. But using the example in the manual: using LinearAlgebra, BenchmarkTools B = \[1.5 2 -4; 2 -1 -3; -4 -3 5\] sB = Sym…

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## [Jump to next/previous block in VS Code](https://discourse.julialang.org/t/jump-to-next-previous-block-in-vs-code/56350)

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**Author:** [@airpmb](https://discourse.julialang.org/u/airpmb)\
**Replies:** 1\
**Last updated:** [March 3, 2021, 9:15am UTC](https://discourse.julialang.org/t/jump-to-next-previous-block-in-vs-code/56350 "2021-03-03T09:15:03Z")

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Is there a keyboard shortcut (or possibility to bind one) that can jump to the next or previous block of code in a file? That is, to the next function, or let block, begin/end block, etc? Basically any kind of structure …

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## [How to change row's values of a column matching pattern in Julia?](https://discourse.julialang.org/t/how-to-change-rows-values-of-a-column-matching-pattern-in-julia/56383)

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**Author:** [@Luigi\_Marongiu](https://discourse.julialang.org/u/Luigi_Marongiu)\
**Replies:** 3\
**Last updated:** [March 3, 2021, 9:13am UTC](https://discourse.julialang.org/t/how-to-change-rows-values-of-a-column-matching-pattern-in-julia/56383 "2021-03-03T09:13:53Z")

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Hello, I have a dataframe where some rows of a given column (‘group’) have a certain value (‘normal’). I would like to change such a value to something else. What would be the syntax? In other words, I am looking for Ju…

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## [Understand Base.similar in doc section Customizing broadcasting](https://discourse.julialang.org/t/understand-base-similar-in-doc-section-customizing-broadcasting/56388)

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**Author:** [@liuyxpp](https://discourse.julialang.org/u/liuyxpp)\
**Replies:** 0\
**Last updated:** [March 3, 2021, 9:01am UTC](https://discourse.julialang.org/t/understand-base-similar-in-doc-section-customizing-broadcasting/56388 "2021-03-03T09:01:56Z")

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I am trying to customizing broadcasting my own type. However, I found the Julia doc section is little bit hard to follow. Can here someone tell me what is the use of the ElType argument in Base.similar(bc::Broadcasted{D…

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## [Bad performance of eachline() on STDIN](https://discourse.julialang.org/t/bad-performance-of-eachline-on-stdin/55701)

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**Author:** [@tferic](https://discourse.julialang.org/u/tferic)\
**Replies:** 35\
**Last updated:** [March 3, 2021, 8:51am UTC](https://discourse.julialang.org/t/bad-performance-of-eachline-on-stdin/55701 "2021-03-03T08:51:18Z")

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Hi I am trying to use Julia for general purpose programming. I am trying to use Julia to create a faster version of a Perl script, which is supposed to create a report on a large logfile, piped into STDIN. The logfile …

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## [Threads, @spawn on Mac - inconsistent behavior](https://discourse.julialang.org/t/threads-spawn-on-mac-inconsistent-behavior/56376)

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**Author:** [@marsmen](https://discourse.julialang.org/u/marsmen)\
**Replies:** 1\
**Last updated:** [March 3, 2021, 7:54am UTC](https://discourse.julialang.org/t/threads-spawn-on-mac-inconsistent-behavior/56376 "2021-03-03T07:54:17Z")

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I’ve a school project to conduct FFTs with Julia. I need to show that running a 1D FFT on an image is faster when running in parallel on the processor’s cores then when running a single instance. I think the reality is, …

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## [Verifying ability to run for repository](https://discourse.julialang.org/t/verifying-ability-to-run-for-repository/56153)

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**Author:** [@meck](https://discourse.julialang.org/u/meck)\
**Replies:** 4\
**Last updated:** [March 3, 2021, 8:00am UTC](https://discourse.julialang.org/t/verifying-ability-to-run-for-repository/56153 "2021-03-03T08:00:56Z")

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Hello, so I am trying to run my first cloned Julia-repository for two days. Constantly I am running into problems to the point where I dont even know anymore, if those scripts in the examples folder are runnable at all. …

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## [Fourier transform of a sine wave, width of the spectral peak](https://discourse.julialang.org/t/fourier-transform-of-a-sine-wave-width-of-the-spectral-peak/56342)

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**Author:** [@BridgeBot](https://discourse.julialang.org/u/BridgeBot)\
**Replies:** 1\
**Last updated:** [March 2, 2021, 11:00pm UTC](https://discourse.julialang.org/t/fourier-transform-of-a-sine-wave-width-of-the-spectral-peak/56342 "2021-03-02T23:00:04Z")

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Hello all! I was wondering, if I’ve got the Fourier transform of a sine wave, how would I calculate the width of that Fourier transform in Julia? Is there a package that does that written in Julia? An example from SciPy …

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## [Map vs Loops & Array Comprehensions in Julia 1.0](https://discourse.julialang.org/t/map-vs-loops-array-comprehensions-in-julia-1-0/16137)

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**Author:** [@mdsalerno](https://discourse.julialang.org/u/mdsalerno)\
**Replies:** 10\
**Last updated:** [March 3, 2021, 7:41am UTC](https://discourse.julialang.org/t/map-vs-loops-array-comprehensions-in-julia-1-0/16137 "2021-03-03T07:41:49Z")

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I’ve seen some older threads on this topic, but is it still the case that loops and array comprehensions are significantly faster than map() in Julia 1.0? If so, can someone provide intuition into why this is the case. …

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## [Best current option for C++ interop?](https://discourse.julialang.org/t/best-current-option-for-c-interop/56186)

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**Author:** [@greatpet](https://discourse.julialang.org/u/greatpet)\
**Replies:** 3\
**Last updated:** [March 3, 2021, 7:10am UTC](https://discourse.julialang.org/t/best-current-option-for-c-interop/56186 "2021-03-03T07:10:02Z")

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Cxx.jl does not support Julia 1.5. What’s the best option calling using C++ libraries? Should I use (plain) C as the bridge?

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## [Setting Time Limits for JuMP (with CBC solver)](https://discourse.julialang.org/t/setting-time-limits-for-jump-with-cbc-solver/56303)

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**Author:** [@acwkim](https://discourse.julialang.org/u/acwkim)\
**Replies:** 6\
**Last updated:** [March 3, 2021, 3:05am UTC](https://discourse.julialang.org/t/setting-time-limits-for-jump-with-cbc-solver/56303 "2021-03-03T03:05:19Z")

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Hi all. Is there a way to set time limit for JuMP models using CBC solver? The “seconds” parameter only limits CPU seconds, which is different from Wallclock seconds. I need to set a limit for Wallclock second! Thanks …

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## [Julia either very fast or very slow, with little in between?](https://discourse.julialang.org/t/julia-either-very-fast-or-very-slow-with-little-in-between/56307)

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**Author:** [@WouterJRV](https://discourse.julialang.org/u/WouterJRV)\
**Replies:** 10\
**Last updated:** [March 3, 2021, 2:36am UTC](https://discourse.julialang.org/t/julia-either-very-fast-or-very-slow-with-little-in-between/56307 "2021-03-03T02:36:01Z")

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I have the impression that Julia commands are often execute very fast (as advertised), but when they are not, it takes ages (up to the point where I’d have to kill it–and system monitor shows that a processor is at 100% …

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## [Update QR factorization by adding a column for orthogonal matching pursuit](https://discourse.julialang.org/t/update-qr-factorization-by-adding-a-column-for-orthogonal-matching-pursuit/56368)

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**Author:** [@mleprovost](https://discourse.julialang.org/u/mleprovost)\
**Replies:** 0\
**Last updated:** [March 2, 2021, 9:44pm UTC](https://discourse.julialang.org/t/update-qr-factorization-by-adding-a-column-for-orthogonal-matching-pursuit/56368 "2021-03-02T21:44:36Z")

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Hello, I am working on the orthogonal matching pursuit algorithm to select a sparse set of features to solve Ax = b. In this algorithm, we add in a greedy fashion a new column (i.e. feature) at each step. The residual …

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## [Never done metaprogramming and now I am thinking I have the perfect use case for i](https://discourse.julialang.org/t/never-done-metaprogramming-and-now-i-am-thinking-i-have-the-perfect-use-case-for-i/56367)

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**Author:** [@BridgeBot](https://discourse.julialang.org/u/BridgeBot)\
**Replies:** 1\
**Last updated:** [March 3, 2021, 12:24am UTC](https://discourse.julialang.org/t/never-done-metaprogramming-and-now-i-am-thinking-i-have-the-perfect-use-case-for-i/56367 "2021-03-03T00:24:02Z")

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Never done metaprogramming and now I am thinking I have the perfect use case for it. I have code that looks like the following and it’s quite tedious: if params.scr\_start &gt; 0 cbset = CallbackSet(cb\_scree…

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## [Link function Bijectors.jl](https://discourse.julialang.org/t/link-function-bijectors-jl/56362)

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**Author:** [@Honza9723](https://discourse.julialang.org/u/Honza9723)\
**Replies:** 3\
**Last updated:** [March 3, 2021, 12:10am UTC](https://discourse.julialang.org/t/link-function-bijectors-jl/56362 "2021-03-03T00:10:17Z")

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Dear All, I would like to ask probably a stupid question. What exactly does link() function? Documentation: link: maps a sample of a random distribution dist from its support to a value in R^n. Example: \` How how exac…

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## [CachingPool-like object that caches objects instead of closures?](https://discourse.julialang.org/t/cachingpool-like-object-that-caches-objects-instead-of-closures/56371)

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**Author:** [@marius311](https://discourse.julialang.org/u/marius311)\
**Replies:** 0\
**Last updated:** [March 2, 2021, 10:50pm UTC](https://discourse.julialang.org/t/cachingpool-like-object-that-caches-objects-instead-of-closures/56371 "2021-03-02T22:50:06Z")

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From what I can tell, CachingPool caches things at the level of the closure, so if you have multiple closures using the same “big” object, it gets sent twice. E.g. function foo(pool) dat = BigObject(...) pmap(wo…

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## [Improving performance in checking prime numbers](https://discourse.julialang.org/t/improving-performance-in-checking-prime-numbers/56365)

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**Author:** [@dariush-bahrami](https://discourse.julialang.org/u/dariush-bahrami)\
**Replies:** 14\
**Last updated:** [March 2, 2021, 10:25pm UTC](https://discourse.julialang.org/t/improving-performance-in-checking-prime-numbers/56365 "2021-03-02T22:25:36Z")

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Hi, I wrote the following code in python with help of numba JIT: from numba import jit @jit(nopython=True) def is\_prime(number): upper\_limit = int(number\*\*0.5) + 1 for i in range(2, upper\_limit): if num…

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## [Whats a better way to remove elements from an array based on index?\`\`\`g = \[55, 7](https://discourse.julialang.org/t/whats-a-better-way-to-remove-elements-from-an-array-based-on-index-g-55-7/56340)

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**Author:** [@BridgeBot](https://discourse.julialang.org/u/BridgeBot)\
**Replies:** 9\
**Last updated:** [March 2, 2021, 9:16pm UTC](https://discourse.julialang.org/t/whats-a-better-way-to-remove-elements-from-an-array-based-on-index-g-55-7/56340 "2021-03-02T21:16:00Z")

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whats a better way to remove elements from an array based on index? g = \[55, 77, 88, 99, 3, 7, 8,99,99, 999\] ix\_drop = 2:4 setdiff(g, g\[ix\_drop\]) This works but it will remove duplicate values… and thats less than desi…

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## [Generic serialization API](https://discourse.julialang.org/t/generic-serialization-api/56366)

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**Author:** [@jzr](https://discourse.julialang.org/u/jzr)\
**Replies:** 0\
**Last updated:** [March 2, 2021, 9:14pm UTC](https://discourse.julialang.org/t/generic-serialization-api/56366 "2021-03-02T21:14:43Z")

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Many file format packages have their own serialization and deserialization functions, with different APIs. I would like to have a single unified API. For example, serialize(data::Serializable, target::AbstractTarget,…

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## [Adding local package results in malformed path (Windows)](https://discourse.julialang.org/t/adding-local-package-results-in-malformed-path-windows/56338)

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**Author:** [@eschoute](https://discourse.julialang.org/u/eschoute)\
**Replies:** 2\
**Last updated:** [March 2, 2021, 8:29pm UTC](https://discourse.julialang.org/t/adding-local-package-results-in-malformed-path-windows/56338 "2021-03-02T20:29:51Z")

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On Windows, I think there is a bug with the location of say “Documents” on a different partition. I moved my Documents folder to a different partition. Steps to reproduce: Cd to E:\\Documents Make a package foo (\>\]gene…

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## [MarkerElement allowable shapes](https://discourse.julialang.org/t/markerelement-allowable-shapes/56356)

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**Author:** [@kevbonham](https://discourse.julialang.org/u/kevbonham)\
**Replies:** 3\
**Last updated:** [March 2, 2021, 8:27pm UTC](https://discourse.julialang.org/t/markerelement-allowable-shapes/56356 "2021-03-02T20:27:01Z")

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I was searching for which shape symbols are allowable in MarkerElements for the marker kwarg. I identified :circle was what I needed, but wasn’t able to find where the possibilities are documented. Using characters like o…

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## [How to access CPLEX.CplexError in JuMP 0.18?](https://discourse.julialang.org/t/how-to-access-cplex-cplexerror-in-jump-0-18/22598)

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**Author:** [@mike\_k](https://discourse.julialang.org/u/mike_k)\
**Replies:** 5\
**Last updated:** [March 2, 2021, 8:18pm UTC](https://discourse.julialang.org/t/how-to-access-cplex-cplexerror-in-jump-0-18/22598 "2021-03-02T20:18:27Z")

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Dear community, I always start cplex like for instance: try status = solve(model) println("status: ", status) println("obj\_val: ", getobjectivevalue(model)) catch msg println("ERROR SOLVING MODEL: ", ms…

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## [Flux unroll](https://discourse.julialang.org/t/flux-unroll/56355)

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**Author:** [@Ul44rich](https://discourse.julialang.org/u/Ul44rich)\
**Replies:** 1\
**Last updated:** [March 2, 2021, 7:01pm UTC](https://discourse.julialang.org/t/flux-unroll/56355 "2021-03-02T19:01:17Z")

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Need hints: Flux “unroll not defined” Thanks

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## [Making Mplay.jl work under Linux](https://discourse.julialang.org/t/making-mplay-jl-work-under-linux/56192)

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**Author:** [@tp2750](https://discourse.julialang.org/u/tp2750)\
**Replies:** 5\
**Last updated:** [March 2, 2021, 5:13pm UTC](https://discourse.julialang.org/t/making-mplay-jl-work-under-linux/56192 "2021-03-02T17:13:41Z")

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Here’s how I got Mplay.jl to work under Linux (Ubuntu 20.04). Mplay.jl writes to a “raw midi device”, and Ubuntu does not have those on by default. To create a “virtual midi device” I do $ sudo modprobe snd-virmidi sn…

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## [StaticArrays field values printed as undef?](https://discourse.julialang.org/t/staticarrays-field-values-printed-as-undef/56318)

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**Author:** [@paulmelis](https://discourse.julialang.org/u/paulmelis)\
**Replies:** 7\
**Last updated:** [March 2, 2021, 4:33pm UTC](https://discourse.julialang.org/t/staticarrays-field-values-printed-as-undef/56318 "2021-03-02T16:33:38Z")

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I’m using a StaticArrays.jl FieldVector for a 3-vector that can be both accessed by field name (v.x) as well as by index (v\[1\]). I also added a length function to get the vector length: using StaticArrays using LinearAl…

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## [Operations on small matrices and BLAS in 1.6.0 RC1](https://discourse.julialang.org/t/operations-on-small-matrices-and-blas-in-1-6-0-rc1/56344)

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**Author:** [@paulmelis](https://discourse.julialang.org/u/paulmelis)\
**Replies:** 2\
**Last updated:** [March 2, 2021, 4:06pm UTC](https://discourse.julialang.org/t/operations-on-small-matrices-and-blas-in-1-6-0-rc1/56344 "2021-03-02T16:06:50Z")

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With some code that uses only 4x4 matrices and that did nothing multi-threaded I was surprised to see CPU usage go up to all 4 cores on my machine (with a large percentage of system time) when using 1.6.0RC1 on Arch Linu…

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## [ANN: New interactive Plots.jl backend for large datasets](https://discourse.julialang.org/t/ann-new-interactive-plots-jl-backend-for-large-datasets/1442)

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**Author:** [@MA\_Laforge](https://discourse.julialang.org/u/MA_Laforge)\
**Replies:** 7\
**Last updated:** [March 2, 2021, 1:22pm UTC](https://discourse.julialang.org/t/ann-new-interactive-plots-jl-backend-for-large-datasets/1442 "2021-03-02T13:22:42Z")

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About InspectDR.jl Fast plotting with a responsive GUI (optional). Target: Quickly identify design/simulation issues & glitches in order to shorten design iterations. Pros Relatively short load times / time to first …

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## [Flux does not update weights only biases](https://discourse.julialang.org/t/flux-does-not-update-weights-only-biases/56330)

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**Author:** [@March-08](https://discourse.julialang.org/u/March-08)\
**Replies:** 1\
**Last updated:** [March 2, 2021, 3:44pm UTC](https://discourse.julialang.org/t/flux-does-not-update-weights-only-biases/56330 "2021-03-02T15:44:25Z")

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After the training step if I display the weights they are the same as at the initialization of the network.

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## [Q: is Distributed not supported in Pluto?](https://discourse.julialang.org/t/q-is-distributed-not-supported-in-pluto/56277)

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**Author:** [@threadedblue](https://discourse.julialang.org/u/threadedblue)\
**Replies:** 5\
**Last updated:** [March 2, 2021, 3:22pm UTC](https://discourse.julialang.org/t/q-is-distributed-not-supported-in-pluto/56277 "2021-03-02T15:22:27Z")

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Q: is Distributed not supported in Pluto? I am liking Pluto so far but today I ran into this: Only process 1 can add and remove workers cluster\_mgmt\_from\_master\_check @ cluster.jl:974 \[inlined\] #addprocs#37 (::Ba…

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