# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1660

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

**Page:** 1661

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## [Why is this scenario of function parameter estimation acting strangely? Using LsqFit](https://discourse.julialang.org/t/why-is-this-scenario-of-function-parameter-estimation-acting-strangely-using-lsqfit/44778)

<div class="topic-metadata">

**Author:** [@kapple](https://discourse.julialang.org/u/kapple)\
**Replies:** 2\
**Last updated:** [August 13, 2020, 1:24pm UTC](https://discourse.julialang.org/t/why-is-this-scenario-of-function-parameter-estimation-acting-strangely-using-lsqfit/44778 "2020-08-13T13:24:24Z")

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FYI for the other definitions of model (commented out), I’ve tested them with the same pair of parameters. using Plots using LsqFit # Define expected curve behaviour # @. model(t, p) = p\[2\]\*exp(p\[1\]\*t) # works # @. mod…

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## [Performance of sparse matrix multiplied with a reshaped view](https://discourse.julialang.org/t/performance-of-sparse-matrix-multiplied-with-a-reshaped-view/44869)

<div class="topic-metadata">

**Author:** [@ckoe-bccms](https://discourse.julialang.org/u/ckoe-bccms)\
**Replies:** 2\
**Last updated:** [August 13, 2020, 1:16pm UTC](https://discourse.julialang.org/t/performance-of-sparse-matrix-multiplied-with-a-reshaped-view/44869 "2020-08-13T13:16:44Z")

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Hello everybody, this question is very similar to other performance questions with sparse matrix multiplications where performance hits boil down to julia falling back to unoptimized methods. Still, I would like to ask …

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## [\[compat\] resolution logic; unsatisfiable requirement that should work?](https://discourse.julialang.org/t/compat-resolution-logic-unsatisfiable-requirement-that-should-work/44855)

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**Author:** [@BioTurboNick](https://discourse.julialang.org/u/BioTurboNick)\
**Replies:** 6\
**Last updated:** [August 13, 2020, 12:55pm UTC](https://discourse.julialang.org/t/compat-resolution-logic-unsatisfiable-requirement-that-should-work/44855 "2020-08-13T12:55:01Z")

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Summary of below: How do I resolve this \[compat\] and Manifest.toml conflict, and how do I keep it from happening again? I have a package that depends on Distributions.jl. Currently its \[compat\] entry contains this: \[c…

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## [Slower execution with multi-threading using @threads macro](https://discourse.julialang.org/t/slower-execution-with-multi-threading-using-threads-macro/44867)

<div class="topic-metadata">

**Author:** [@trathi](https://discourse.julialang.org/u/trathi)\
**Replies:** 5\
**Last updated:** [August 13, 2020, 12:45pm UTC](https://discourse.julialang.org/t/slower-execution-with-multi-threading-using-threads-macro/44867 "2020-08-13T12:45:40Z")

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I am running into an issue where allowing multi-threading leads to slower execution time. Following is the simple code where I am testing it: function sqr(x) return x\*x end y = zeros(10) for i=1:8 y\[i\] = sqr(i)…

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## [Fast sparse interval matrices?](https://discourse.julialang.org/t/fast-sparse-interval-matrices/44864)

<div class="topic-metadata">

**Author:** [@fph](https://discourse.julialang.org/u/fph)\
**Replies:** 1\
**Last updated:** [August 13, 2020, 12:41pm UTC](https://discourse.julialang.org/t/fast-sparse-interval-matrices/44864 "2020-08-13T12:41:50Z")

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I have noticed that using sparse interval matrices is a big performance hit: using ValidatedNumerics, SparseArrays import ValidatedNumerics.IntervalArithmetic.hull n = 10000 P = sprand(n, n, 0.01) Q = sprandn(n, n, 0.0…

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## [How to jump to julia std lib source code in vscoe](https://discourse.julialang.org/t/how-to-jump-to-julia-std-lib-source-code-in-vscoe/44803)

<div class="topic-metadata">

**Author:** [@hzgzh](https://discourse.julialang.org/u/hzgzh)\
**Replies:** 3\
**Last updated:** [August 13, 2020, 11:29am UTC](https://discourse.julialang.org/t/how-to-jump-to-julia-std-lib-source-code-in-vscoe/44803 "2020-08-13T11:29:33Z")

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sorry for my poor english. In vscode when I hove on svd function,it display a window about function instruction,I get this svd!(A; full::Bool = false, alg::Algorithm = default\_svd\_alg(A)) -\> SVD svd! is the same as svd…

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## [Why should I not "use unnecessary static parameters"](https://discourse.julialang.org/t/why-should-i-not-use-unnecessary-static-parameters/44859)

<div class="topic-metadata">

**Author:** [@HenrikM](https://discourse.julialang.org/u/HenrikM)\
**Replies:** 9\
**Last updated:** [August 13, 2020, 11:10am UTC](https://discourse.julialang.org/t/why-should-i-not-use-unnecessary-static-parameters/44859 "2020-08-13T11:10:41Z")

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The style guide says Don’t use unnecessary static parameters but does not explain why. Is this just a question of style or are there other considerations?

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## [Converting to DataFrame](https://discourse.julialang.org/t/converting-to-dataframe/44828)

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**Author:** [@danicaratelli](https://discourse.julialang.org/u/danicaratelli)\
**Replies:** 4\
**Last updated:** [August 13, 2020, 10:55am UTC](https://discourse.julialang.org/t/converting-to-dataframe/44828 "2020-08-13T10:55:17Z")

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I am loading a large .dta file and then converting it to a DataFrame. However, because of its size, the conversion takes a very long time (~20mins). I don’t need all of the columns in the file so I am wondering whether a…

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## [Turing.jl: DomainError with -960.1841700397322:](https://discourse.julialang.org/t/turing-jl-domainerror-with-960-1841700397322/44829)

<div class="topic-metadata">

**Author:** [@vkv](https://discourse.julialang.org/u/vkv)\
**Replies:** 3\
**Last updated:** [August 13, 2020, 9:46am UTC](https://discourse.julialang.org/t/turing-jl-domainerror-with-960-1841700397322/44829 "2020-08-13T09:46:58Z")

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Running the code results in the following error using Turing, ReverseDiff, Memoization Turing.setadbackend(:reversediff) Turing.setrdcache(true) y1 = rand(10) A1 = rand(10, 10) function logsumexp(mat) max\_ = maxi…

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## [Problem setup for UODE testing](https://discourse.julialang.org/t/problem-setup-for-uode-testing/44422)

<div class="topic-metadata">

**Author:** [@Libbum](https://discourse.julialang.org/u/Libbum)\
**Replies:** 11\
**Last updated:** [August 13, 2020, 8:38am UTC](https://discourse.julialang.org/t/problem-setup-for-uode-testing/44422 "2020-08-13T08:38:33Z")

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Hi all, I’m following these Universal ODE examples, trying to get one of my own systems to work. Having a good deal of issues getting things to solve & I hope someone can see the error I’m making. Problem is that I see…

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## [\[Tutorial\] Develop Julia inside Docker container](https://discourse.julialang.org/t/tutorial-develop-julia-inside-docker-container/44861)

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**Author:** [@aurelio-amerio](https://discourse.julialang.org/u/aurelio-amerio)\
**Replies:** 0\
**Last updated:** [August 13, 2020, 8:00am UTC](https://discourse.julialang.org/t/tutorial-develop-julia-inside-docker-container/44861 "2020-08-13T08:00:34Z")

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Hello everybody, after the announcement made at the JuliaCon2020 about Juno moving to VSCode, I was exited to explore this editor which I had never used before. It turns out it is really great and it offers many capab…

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## [Error Precompiling Dierckx](https://discourse.julialang.org/t/error-precompiling-dierckx/44720)

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**Author:** [@yangqifan](https://discourse.julialang.org/u/yangqifan)\
**Replies:** 4\
**Last updated:** [August 13, 2020, 7:51am UTC](https://discourse.julialang.org/t/error-precompiling-dierckx/44720 "2020-08-13T07:51:34Z")

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Hi. I have try DiffEqParamEstim.jl in JulilaPro-1.5.0 in windows10. when I using the package, it tells me Dierckx is not properly installed. using DiffEqParamEstim \[ Info: Precompiling DiffEqParamEstim \[1130ab10-4a5a-5…

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## [BinaryBuilder.jl: how to select gcc 9.1.0](https://discourse.julialang.org/t/binarybuilder-jl-how-to-select-gcc-9-1-0/44857)

<div class="topic-metadata">

**Author:** [@MichelJuillard](https://discourse.julialang.org/u/MichelJuillard)\
**Replies:** 2\
**Last updated:** [August 13, 2020, 7:36am UTC](https://discourse.julialang.org/t/binarybuilder-jl-how-to-select-gcc-9-1-0/44857 "2020-08-13T07:36:52Z")

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I have a binary executable that needs to be compiled with gcc 9.1.0. I see in the code of BinaryBuilderBase.jl that there is provision for gcc 9.1.0, but I don’t undertstand how I can request such a shard. Selecting libg…

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## [Should macros get an \`\_\_istoplevel\_\_\` or \`\_\_scope\_\_\` argument?](https://discourse.julialang.org/t/should-macros-get-an-istoplevel-or-scope-argument/44850)

<div class="topic-metadata">

**Author:** [@marius311](https://discourse.julialang.org/u/marius311)\
**Replies:** 5\
**Last updated:** [August 13, 2020, 7:05am UTC](https://discourse.julialang.org/t/should-macros-get-an-istoplevel-or-scope-argument/44850 "2020-08-13T07:05:23Z")

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Because the same code will behave differently in global vs local scope, if one wants to write a macro which can work in both, in theory it needs to know into which scope its being expanded, right? I’m running into this …

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## [Proper syntax for adding reactions to a reaction network using addreaction!() function in Catalyst.jl](https://discourse.julialang.org/t/proper-syntax-for-adding-reactions-to-a-reaction-network-using-addreaction-function-in-catalyst-jl/44804)

<div class="topic-metadata">

**Author:** [@spock1](https://discourse.julialang.org/u/spock1)\
**Replies:** 3\
**Last updated:** [August 13, 2020, 4:15am UTC](https://discourse.julialang.org/t/proper-syntax-for-adding-reactions-to-a-reaction-network-using-addreaction-function-in-catalyst-jl/44804 "2020-08-13T04:15:42Z")

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I recently started to thinking about switching my simulations to Julia and got to know about Catalyst.jl package and its convenient macro to create and modify reaction networks. I wanted to add a reaction to an already…

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## [Can you make this shorter, more elegant, and more julia-esque](https://discourse.julialang.org/t/can-you-make-this-shorter-more-elegant-and-more-julia-esque/44848)

<div class="topic-metadata">

**Author:** [@systems](https://discourse.julialang.org/u/systems)\
**Replies:** 4\
**Last updated:** [August 13, 2020, 3:29am UTC](https://discourse.julialang.org/t/can-you-make-this-shorter-more-elegant-and-more-julia-esque/44848 "2020-08-13T03:29:16Z")

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Hi Can you make this code more elegant flag1 = (0,1) flag2 = (0,1) flag3 = (0,1) flag4 = (0,1) flag5 = (0,1) for i1 in flag1 for i2 in flag2 for i3 in flag3 for i4 in flag4 fo…

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## [Rand() period](https://discourse.julialang.org/t/rand-period/44837)

<div class="topic-metadata">

**Author:** [@steve1313](https://discourse.julialang.org/u/steve1313)\
**Replies:** 1\
**Last updated:** [August 13, 2020, 12:50am UTC](https://discourse.julialang.org/t/rand-period/44837 "2020-08-13T00:50:15Z")

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What is the period of Julia’s rand() function (default rand(), returning Float64)? How many times can you call rand() before it starts repeating?

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## [\[ANN\] KittyTerminalImages.jl: Display Julia output images directly in your terminal](https://discourse.julialang.org/t/ann-kittyterminalimages-jl-display-julia-output-images-directly-in-your-terminal/44831)

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**Author:** [@simonschoelly](https://discourse.julialang.org/u/simonschoelly)\
**Replies:** 5\
**Last updated:** [August 12, 2020, 11:40pm UTC](https://discourse.julialang.org/t/ann-kittyterminalimages-jl-display-julia-output-images-directly-in-your-terminal/44831 "2020-08-12T23:40:33Z")

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Hello, Quite a while ago I started KittyTerminalImages.jl - a package that allows one to show images generated by Julia directly in the terminal. I never registered that package as it is still very experimental and I di…

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## [TBB and Julia threads composability](https://discourse.julialang.org/t/tbb-and-julia-threads-composability/43688)

<div class="topic-metadata">

**Author:** [@hros](https://discourse.julialang.org/u/hros)\
**Replies:** 1\
**Last updated:** [August 12, 2020, 11:37pm UTC](https://discourse.julialang.org/t/tbb-and-julia-threads-composability/43688 "2020-08-12T23:37:53Z")

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I would like to call parallel C++ libraries from a multithreaded Julia program, using the composable parallelism of Julia and Intel’s TBB in tandem. While the Julia thread blog post and the docs do not address this issu…

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## [Simultaneous left and right multiplication of a matrix](https://discourse.julialang.org/t/simultaneous-left-and-right-multiplication-of-a-matrix/44823)

<div class="topic-metadata">

**Author:** [@mleprovost](https://discourse.julialang.org/u/mleprovost)\
**Replies:** 1\
**Last updated:** [August 12, 2020, 11:09pm UTC](https://discourse.julialang.org/t/simultaneous-left-and-right-multiplication-of-a-matrix/44823 "2020-08-12T23:09:41Z")

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Hello, I am computing a positive definite matrix H (in my case it is a Hessian) and I would like to transform it into another basis according to P^THP with P an upper triangular matrix. Is there an optimized routine to…

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## [Mmap error on windows](https://discourse.julialang.org/t/mmap-error-on-windows/24594)

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**Author:** [@ranjan](https://discourse.julialang.org/u/ranjan)\
**Replies:** 5\
**Last updated:** [August 12, 2020, 10:46pm UTC](https://discourse.julialang.org/t/mmap-error-on-windows/24594 "2020-08-12T22:46:49Z")

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Hello, I am using SharedArrays to accumulate matrices that have been generated by different worker processes in my package Circuitscape. However, on windows, when I run the tests, I get: Got exception outside of a @tes…

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## [Legend in pie chart](https://discourse.julialang.org/t/legend-in-pie-chart/44832)

<div class="topic-metadata">

**Author:** [@angeloaliano1](https://discourse.julialang.org/u/angeloaliano1)\
**Replies:** 0\
**Last updated:** [August 12, 2020, 10:25pm UTC](https://discourse.julialang.org/t/legend-in-pie-chart/44832 "2020-08-12T22:25:12Z")

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Hello, I have a little problem: I cannot to show the legend of my pie chat below: using Plots plotly() x = \["Nerds", "Hackers", "Scientists"\] y = \[0.4, 0.35, 0.25\] pie(x, y, l=0.5) Anyone can help me please?

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## [Query.@mutate weirdness (bug?)](https://discourse.julialang.org/t/query-mutate-weirdness-bug/44642)

<div class="topic-metadata">

**Author:** [@ilyagr](https://discourse.julialang.org/u/ilyagr)\
**Replies:** 2\
**Last updated:** [August 12, 2020, 9:49pm UTC](https://discourse.julialang.org/t/query-mutate-weirdness-bug/44642 "2020-08-12T21:49:35Z")

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As I was trying to figure out another question, I found something that might be a bug (or perhaps a documentation bug) in Query.jl. According to the docs: The @mutate command has the form source |\> @mutate(args...).…

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## [UnsafePointers.jl: Convenient (but unsafe) pointer accesses](https://discourse.julialang.org/t/unsafepointers-jl-convenient-but-unsafe-pointer-accesses/44750)

<div class="topic-metadata">

**Author:** [@cjdoris](https://discourse.julialang.org/u/cjdoris)\
**Replies:** 2\
**Last updated:** [August 12, 2020, 9:38pm UTC](https://discourse.julialang.org/t/unsafepointers-jl-convenient-but-unsafe-pointer-accesses/44750 "2020-08-12T21:38:02Z")

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Sometimes you need to interface with a C library. Sometimes that C library gives you pointers to structs containing pointers to arrays of pointers to… # In C you do this: p-\>second\_field\[3\] = 9 # In Julia you do this: …

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## [Varying parameter in a function](https://discourse.julialang.org/t/varying-parameter-in-a-function/44783)

<div class="topic-metadata">

**Author:** [@samerb](https://discourse.julialang.org/u/samerb)\
**Replies:** 14\
**Last updated:** [August 12, 2020, 8:47pm UTC](https://discourse.julialang.org/t/varying-parameter-in-a-function/44783 "2020-08-12T20:47:19Z")

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I am trying to examine how the solution to an optimization problem changes as some parameters are changed in the objective. As a preliminary step, I am just trying to get comfortable modifying parameters in a function. H…

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## [Looking for a beginner/intermediate Julia! development role](https://discourse.julialang.org/t/looking-for-a-beginner-intermediate-julia-development-role/44807)

<div class="topic-metadata">

**Author:** [@Clark\_Cruz](https://discourse.julialang.org/u/Clark_Cruz)\
**Replies:** 1\
**Last updated:** [August 12, 2020, 8:39pm UTC](https://discourse.julialang.org/t/looking-for-a-beginner-intermediate-julia-development-role/44807 "2020-08-12T20:39:44Z")

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Hello folks, I hope this note finds you safe and well. I am looking for a beginner/intermediate Julia! development role. I am in the New York City, NY area and I have experience working remotely. I have worked in inve…

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## [Which line is resulting is huge memory allocation?](https://discourse.julialang.org/t/which-line-is-resulting-is-huge-memory-allocation/44822)

<div class="topic-metadata">

**Author:** [@Sanji\_Vinsmoke](https://discourse.julialang.org/u/Sanji_Vinsmoke)\
**Replies:** 10\
**Last updated:** [August 12, 2020, 8:23pm UTC](https://discourse.julialang.org/t/which-line-is-resulting-is-huge-memory-allocation/44822 "2020-08-12T20:23:30Z")

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This code below is running very very slow must be due to the ridiculous number of memory allocations. input = "1113222113" function lookandsay(s::AbstractString)::AbstractString result = "" i = 1 while i \<=…

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## [Why can't methods be defined inside a \`let\` block?](https://discourse.julialang.org/t/why-cant-methods-be-defined-inside-a-let-block/44818)

<div class="topic-metadata">

**Author:** [@nben](https://discourse.julialang.org/u/nben)\
**Replies:** 5\
**Last updated:** [August 12, 2020, 7:27pm UTC](https://discourse.julialang.org/t/why-cant-methods-be-defined-inside-a-let-block/44818 "2020-08-12T19:27:14Z")

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When one runs the following code, my expectation is that three methods would get defined. # Default equal function: preferred\_equal\_fn(x) = (===) # Numbers use isequal let x = isequal preferred\_equal\_fn(::Type{T}) …

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## [Simple Mat-Vec multiply (understanding performance, without the bugs)](https://discourse.julialang.org/t/simple-mat-vec-multiply-understanding-performance-without-the-bugs/44762)

<div class="topic-metadata">

**Author:** [@dlakelan](https://discourse.julialang.org/u/dlakelan)\
**Replies:** 16\
**Last updated:** [August 12, 2020, 11:22am UTC](https://discourse.julialang.org/t/simple-mat-vec-multiply-understanding-performance-without-the-bugs/44762 "2020-08-12T11:22:53Z")

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I wanted to show someone that straight ahead Julia code is reasonably fast. So I used the following: using BenchmarkTools,LinearAlgebra function matmul(A,v) if size(A,2) != length(v) throw(DimensionMismatch…

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## [Activating virtual environment on workers](https://discourse.julialang.org/t/activating-virtual-environment-on-workers/44806)

<div class="topic-metadata">

**Author:** [@martincornejo](https://discourse.julialang.org/u/martincornejo)\
**Replies:** 5\
**Last updated:** [August 12, 2020, 3:15pm UTC](https://discourse.julialang.org/t/activating-virtual-environment-on-workers/44806 "2020-08-12T15:15:37Z")

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Say we want to use certain package (that is only available in a project-specific virtual environment) in a distributed manner. (@v1.5) pkg\> activate . Activating environment at \`C:\\Users\\Martin Cornejo\\MyProject\\Projec…

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