# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1192

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

**Page:** 1193

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## [Forwarddiff parametric gradient?](https://discourse.julialang.org/t/forwarddiff-parametric-gradient/72302)

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**Author:** [@lrnv](https://discourse.julialang.org/u/lrnv)\
**Replies:** 12\
**Last updated:** [November 30, 2021, 6:02pm UTC](https://discourse.julialang.org/t/forwarddiff-parametric-gradient/72302 "2021-11-30T18:02:30Z")

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Hey, Suppose I have a function that takes two vector parameters : function f(p,q) # takes two vectors of same size return sum(p .\* q) # return only one value end I want to obtain the gradient of f with respect to …

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## [DataFramesMeta question](https://discourse.julialang.org/t/dataframesmeta-question/72268)

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**Author:** [@benibilme](https://discourse.julialang.org/u/benibilme)\
**Replies:** 9\
**Last updated:** [November 30, 2021, 5:25pm UTC](https://discourse.julialang.org/t/dataframesmeta-question/72268 "2021-11-30T17:25:36Z")

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I am trying to learn DataFramesMeta LINQ similar syntax. I have not been able to come up the proper counter of following very simple DataFrames syntax for DataFramesMeta Get number of rows. combine(df, nrow)

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## [Update a variable in an HDF5 file](https://discourse.julialang.org/t/update-a-variable-in-an-hdf5-file/62341)

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**Author:** [@davidwallis](https://discourse.julialang.org/u/davidwallis)\
**Replies:** 7\
**Last updated:** [November 30, 2021, 4:37pm UTC](https://discourse.julialang.org/t/update-a-variable-in-an-hdf5-file/62341 "2021-11-30T16:37:59Z")

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Simple problem, but it’s driving me mad. How do I update a dataset in an HDF5 file? Thanks julia\> tp2\[“callParams”\]\[“width”\] :1234: HDF5.Dataset: /callParams/width (file: testproj2.h5 xfer\_mode: 0) julia\> read(tp2\[“c…

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## [Spurious memory allocation even though @code\_warntype looks fine (no types marked in red)](https://discourse.julialang.org/t/spurious-memory-allocation-even-though-code-warntype-looks-fine-no-types-marked-in-red/22367)

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**Author:** [@fverdugo](https://discourse.julialang.org/u/fverdugo)\
**Replies:** 7\
**Last updated:** [November 30, 2021, 4:24pm UTC](https://discourse.julialang.org/t/spurious-memory-allocation-even-though-code-warntype-looks-fine-no-types-marked-in-red/22367 "2021-11-30T16:24:14Z")

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I have trouble with this piece of code: struct Foo{T,N} a::Array{T,N} l::Int end function Base.iterate(foo::Foo{T,N}) where {T,N} v = Array{Float64,N}(undef,size(foo.a)) k = 0 if k == foo.l; return n…

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## [Reshape long](https://discourse.julialang.org/t/reshape-long/72257)

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**Author:** [@Matthew](https://discourse.julialang.org/u/Matthew)\
**Replies:** 4\
**Last updated:** [November 30, 2021, 3:15pm UTC](https://discourse.julialang.org/t/reshape-long/72257 "2021-11-30T15:15:59Z")

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Hi everyone, I’m loving Julia but am having some difficulties reshaping my dataframe to a “long” format. df = DataFrame(ID = 1:3, sex = \[0,1,0\], inc80 = \[5500,2200,2000\], inc81 = incB, inc82 = incC, …

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## [Hash and SHA of dictionaries and dataframes](https://discourse.julialang.org/t/hash-and-sha-of-dictionaries-and-dataframes/72301)

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**Author:** [@JackStrauss](https://discourse.julialang.org/u/JackStrauss)\
**Replies:** 0\
**Last updated:** [November 30, 2021, 2:36pm UTC](https://discourse.julialang.org/t/hash-and-sha-of-dictionaries-and-dataframes/72301 "2021-11-30T14:36:56Z")

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Hello everybody I have code where I need to redo a calculation if a large dataset or model specification change. I have a large number of such datasets. In R I would just use the digest() function which provides a SHA …

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## [Finding multiple fixed points of a non-linear problem](https://discourse.julialang.org/t/finding-multiple-fixed-points-of-a-non-linear-problem/72292)

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**Author:** [@Joseph\_Bradley](https://discourse.julialang.org/u/Joseph_Bradley)\
**Replies:** 3\
**Last updated:** [November 30, 2021, 1:50pm UTC](https://discourse.julialang.org/t/finding-multiple-fixed-points-of-a-non-linear-problem/72292 "2021-11-30T13:50:25Z")

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Hi! I’m looking for some Julia code that will find all the fixed points of a non-linear problem. Specifically, I’m looking for all the solutions of this fixed point problem: m = tanh(am + b) where a and b are paramete…

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## [Production deployment of Genie app with systemd](https://discourse.julialang.org/t/production-deployment-of-genie-app-with-systemd/72281)

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**Author:** [@PaulDebus](https://discourse.julialang.org/u/PaulDebus)\
**Replies:** 5\
**Last updated:** [November 30, 2021, 1:46pm UTC](https://discourse.julialang.org/t/production-deployment-of-genie-app-with-systemd/72281 "2021-11-30T13:46:26Z")

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I am trying to deploy a website built with Genie to production behind a nginx reverse proxy. The documentation and most tutorials suggest using screen to keep the app running. I would however prefer using systemd, as it …

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## [How to get the name of macro calling function?](https://discourse.julialang.org/t/how-to-get-the-name-of-macro-calling-function/72286)

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**Author:** [@Impressium](https://discourse.julialang.org/u/Impressium)\
**Replies:** 3\
**Last updated:** [November 30, 2021, 1:48pm UTC](https://discourse.julialang.org/t/how-to-get-the-name-of-macro-calling-function/72286 "2021-11-30T13:48:56Z")

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Hey al :slight\_smile: It’s probably easier to ask the question with an example: module M macro m() get\_name\_of\_calling\_function() |\> println get\_name\_of\_calling\_module() |\> println end function f() @m() …

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## [FASTX.FASTA.Reader, no method matching error](https://discourse.julialang.org/t/fastx-fasta-reader-no-method-matching-error/72240)

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**Author:** [@Lamma](https://discourse.julialang.org/u/Lamma)\
**Replies:** 7\
**Last updated:** [November 30, 2021, 1:21pm UTC](https://discourse.julialang.org/t/fastx-fasta-reader-no-method-matching-error/72240 "2021-11-30T13:21:34Z")

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I am using the ´FASTX\` package to stream over a large fasta file but am getting a no method matching error: ERROR: LoadError: TaskFailedException Stacktrace: \[1\] wait @ ./task.jl:334 \[inlined\] \[2\] threading\_run(fun…

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## [@time every evaluation in repl](https://discourse.julialang.org/t/time-every-evaluation-in-repl/72275)

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**Author:** [@jzr](https://discourse.julialang.org/u/jzr)\
**Replies:** 7\
**Last updated:** [November 30, 2021, 1:09pm UTC](https://discourse.julialang.org/t/time-every-evaluation-in-repl/72275 "2021-11-30T13:09:52Z")

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Is it possible to hook the repl to @time every eval?

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## [Macro: quote versus colon](https://discourse.julialang.org/t/macro-quote-versus-colon/36041)

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**Author:** [@erlebach](https://discourse.julialang.org/u/erlebach)\
**Replies:** 3\
**Last updated:** [November 30, 2021, 12:14pm UTC](https://discourse.julialang.org/t/macro-quote-versus-colon/36041 "2021-11-30T12:14:09Z")

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I am going over macros, and decided to test whether quote and colon were identical. See the code below. Apparently they are not. And if not, it means that there likely side effects in rare instances. What am I missing? T…

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## [Strange way to recover performance with polymorphic types](https://discourse.julialang.org/t/strange-way-to-recover-performance-with-polymorphic-types/72250)

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**Author:** [@peremato](https://discourse.julialang.org/u/peremato)\
**Replies:** 5\
**Last updated:** [November 30, 2021, 8:57am UTC](https://discourse.julialang.org/t/strange-way-to-recover-performance-with-polymorphic-types/72250 "2021-11-30T08:57:43Z")

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This is a followup of dramatic performance change by adding additional unused method. The explanation was the existing limit on the number of overloaded methods the Julia optimizer is looking to decide the actual return …

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## ["Skip" parameter XLSX package](https://discourse.julialang.org/t/skip-parameter-xlsx-package/72239)

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**Author:** [@jnewbie](https://discourse.julialang.org/u/jnewbie)\
**Replies:** 2\
**Last updated:** [November 30, 2021, 8:04am UTC](https://discourse.julialang.org/t/skip-parameter-xlsx-package/72239 "2021-11-30T08:04:26Z")

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Hi everyone, I am basically “translating” a R code into a Julia code, here is one of the line of the R code : read\_excel(‘Results.xlsx’, sheet = ‘x’, col\_names = FALSE, col\_types = “numeric”, na = “”, skip = 0) To d…

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## [Incorrect result from \`floor\` function](https://discourse.julialang.org/t/incorrect-result-from-floor-function/72262)

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**Author:** [@eshanuniyal](https://discourse.julialang.org/u/eshanuniyal)\
**Replies:** 10\
**Last updated:** [November 30, 2021, 7:05am UTC](https://discourse.julialang.org/t/incorrect-result-from-floor-function/72262 "2021-11-30T07:05:33Z")

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I was working on a Project Euler problem and discovered what looks like a bug in the floor function; with some large numbers d, floor(Int, d/9) seems to round up instead of down. I haven’t looked into it too much, but on…

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## [How about new feature of \`:auto\` symbol of \`DataFrame\`?](https://discourse.julialang.org/t/how-about-new-feature-of-auto-symbol-of-dataframe/72271)

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**Author:** [@rmsmsgood](https://discourse.julialang.org/u/rmsmsgood)\
**Replies:** 3\
**Last updated:** [November 30, 2021, 6:34am UTC](https://discourse.julialang.org/t/how-about-new-feature-of-auto-symbol-of-dataframe/72271 "2021-11-30T06:34:06Z")

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julia\> DataFrame(\[1 0; 2 0\], :auto) 2×2 DataFrame Row │ x1 x2 │ Int64 Int64 ─────┼────────────── 1 │ 1 0 2 │ 2 0 Recently, the :auto symbol can be used to above result. I want new …

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## [Concept of continuous depths for neural networks in UDEs](https://discourse.julialang.org/t/concept-of-continuous-depths-for-neural-networks-in-udes/72090)

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**Author:** [@saadfaizan](https://discourse.julialang.org/u/saadfaizan)\
**Replies:** 7\
**Last updated:** [November 30, 2021, 5:52am UTC](https://discourse.julialang.org/t/concept-of-continuous-depths-for-neural-networks-in-udes/72090 "2021-11-30T05:52:33Z")

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I recently came across the concept of continuous depth in Neural ODEs. I was wondering if the neural networks in the UDE framework have a similar concept of continuous depths. @ChrisRackauckas

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## [Why does Dates allow non-broadcasted arithmatic?](https://discourse.julialang.org/t/why-does-dates-allow-non-broadcasted-arithmatic/13205)

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**Author:** [@pdeffebach](https://discourse.julialang.org/u/pdeffebach)\
**Replies:** 6\
**Last updated:** [November 30, 2021, 3:27am UTC](https://discourse.julialang.org/t/why-does-dates-allow-non-broadcasted-arithmatic/13205 "2021-11-30T03:27:41Z")

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https://github.com/JuliaLang/julia/blob/f8d82ccba81223c9d0d43e4077acb2a208bedc7a/stdlib/Dates/src/arithmetic.jl#L94 In the code for Dates there is the following: # TimeType, AbstractArray{TimeType} (-)(x::AbstractArray…

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## [Performance of custom lt function in sort!](https://discourse.julialang.org/t/performance-of-custom-lt-function-in-sort/72264)

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**Author:** [@Ian\_Slagle](https://discourse.julialang.org/u/Ian_Slagle)\
**Replies:** 2\
**Last updated:** [November 30, 2021, 2:43am UTC](https://discourse.julialang.org/t/performance-of-custom-lt-function-in-sort/72264 "2021-11-30T02:43:21Z")

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I am interested in writing my own lt function within a sort for better performance in a specific use case (in this case, I only care if the numbers are a set length apart from one another). However, it seems that any sub…

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## [Plotting fails on a fresh MacOS install](https://discourse.julialang.org/t/plotting-fails-on-a-fresh-macos-install/70272)

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**Author:** [@Alexandre\_Champagne](https://discourse.julialang.org/u/Alexandre_Champagne)\
**Replies:** 3\
**Last updated:** [November 30, 2021, 1:12am UTC](https://discourse.julialang.org/t/plotting-fails-on-a-fresh-macos-install/70272 "2021-11-30T01:12:24Z")

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Just installed the latest version of Julia, then tried running a small example found on a forum post in here: using Plots; pyplot() x=range(-2,stop=2,length=100) y=range(sqrt(2),stop=2,length=100) f(x,y) = x\*y-x-y+1 plo…

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## [\[ANN\] CliffordAlgebras.jl](https://discourse.julialang.org/t/ann-cliffordalgebras-jl/71955)

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**Author:** [@atell\_soundtheory](https://discourse.julialang.org/u/atell_soundtheory)\
**Replies:** 19\
**Last updated:** [November 30, 2021, 1:07am UTC](https://discourse.julialang.org/t/ann-cliffordalgebras-jl/71955 "2021-11-30T01:07:35Z")

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I’m pleased to announce the first release of CliffordAlgebras.jl, a package for performing calculations in generic Clifford algebras / geometric algebras. Package registration is still pending. https://github.com/ATell-…

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## [Call compiled Julia function from Python](https://discourse.julialang.org/t/call-compiled-julia-function-from-python/72168)

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**Author:** [@Darel](https://discourse.julialang.org/u/Darel)\
**Replies:** 7\
**Last updated:** [November 30, 2021, 1:03am UTC](https://discourse.julialang.org/t/call-compiled-julia-function-from-python/72168 "2021-11-30T01:03:22Z")

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Hello, I have a Julia function that accepts a sparse matrix and some parameters, and returns two sparse matrices as a result. I know that there is a Pycall, but I don’t want to call an active instance of installed Juli…

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## [View with single value](https://discourse.julialang.org/t/view-with-single-value/28762)

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**Author:** [@lmiq](https://discourse.julialang.org/u/lmiq)\
**Replies:** 14\
**Last updated:** [November 30, 2021, 1:03am UTC](https://discourse.julialang.org/t/view-with-single-value/28762 "2021-11-30T01:03:07Z")

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I want to pass a single value from an array to a function, and I thought this could be faster using view. However, since view returns not an integer but an array, if the function receives an integer at that position, the…

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## [Threads.@threads slow down when arrays become too large](https://discourse.julialang.org/t/threads-threads-slow-down-when-arrays-become-too-large/72261)

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**Author:** [@mlavrisa](https://discourse.julialang.org/u/mlavrisa)\
**Replies:** 1\
**Last updated:** [November 29, 2021, 11:57pm UTC](https://discourse.julialang.org/t/threads-threads-slow-down-when-arrays-become-too-large/72261 "2021-11-29T23:57:34Z")

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Hello all, I’m 3 days into my Julia journey - coming from python, I’m very excited by the speed. I’m currently toying with multithreading. I actually have tons of questions, but let’s start with this one… In the actual …

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## [Turing model fail due to extreme outliers sampled in Exponential distribution?](https://discourse.julialang.org/t/turing-model-fail-due-to-extreme-outliers-sampled-in-exponential-distribution/72174)

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**Author:** [@amit1](https://discourse.julialang.org/u/amit1)\
**Replies:** 14\
**Last updated:** [November 29, 2021, 11:16pm UTC](https://discourse.julialang.org/t/turing-model-fail-due-to-extreme-outliers-sampled-in-exponential-distribution/72174 "2021-11-29T23:16:31Z")

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I am modelling some textbook models (minimal example given below) using Turing # Data =================== contact = \[1, 1, 1, 2, 2, 2, 2, 1, 2, 1\] total\_tools = \[ 13 ,22 ,24 ,43 ,33 ,19 ,40 ,28 ,55 ,71\] population = \[1…

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## [How to get padding between axis label and ticks with VegaLite.jl?](https://discourse.julialang.org/t/how-to-get-padding-between-axis-label-and-ticks-with-vegalite-jl/72249)

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**Author:** [@Nosferican](https://discourse.julialang.org/u/Nosferican)\
**Replies:** 1\
**Last updated:** [November 29, 2021, 11:13pm UTC](https://discourse.julialang.org/t/how-to-get-padding-between-axis-label-and-ticks-with-vegalite-jl/72249 "2021-11-29T23:13:33Z")

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I am having an issue with VegaLite.jl where the label is overlapping with the ticks in the y-axis. I haven’t been able to find any parameter to add some padding between the two values. CC: @davidanthoff

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## [Check if already compiled](https://discourse.julialang.org/t/check-if-already-compiled/72259)

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**Author:** [@jzr](https://discourse.julialang.org/u/jzr)\
**Replies:** 0\
**Last updated:** [November 29, 2021, 11:00pm UTC](https://discourse.julialang.org/t/check-if-already-compiled/72259 "2021-11-29T23:00:24Z")

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Is it possible to check if an expression f(x1, x2) will need to compile more or if it has already been compiled?

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## [Performance of simple broadcasting operations with many arguments](https://discourse.julialang.org/t/performance-of-simple-broadcasting-operations-with-many-arguments/72213)

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**Author:** [@Marco\_Lombardi](https://discourse.julialang.org/u/Marco_Lombardi)\
**Replies:** 15\
**Last updated:** [November 29, 2021, 10:09pm UTC](https://discourse.julialang.org/t/performance-of-simple-broadcasting-operations-with-many-arguments/72213 "2021-11-29T22:09:48Z")

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I am puzzled by some microbenchmarks tests I did on very simple broadcasting operations. julia\> using BenchmarkTools julia\> n = 10000; x = rand(n); y = rand(n); z = rand(n); t = rand(n); r = zeros(n); julia\> @belapsed $…

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## [Construct multiple graphs from sparse adjacency matrix](https://discourse.julialang.org/t/construct-multiple-graphs-from-sparse-adjacency-matrix/72256)

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**Author:** [@markmbaum](https://discourse.julialang.org/u/markmbaum)\
**Replies:** 4\
**Last updated:** [November 29, 2021, 8:38pm UTC](https://discourse.julialang.org/t/construct-multiple-graphs-from-sparse-adjacency-matrix/72256 "2021-11-29T20:38:26Z")

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I have a sparse adjacency matrix (SparseMatrixCSC) representing connections between the elements of a collection. I see that I can neatly convert it to a graph with the Graph constructor from Graphs.jl. However, I know …

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## [Unable to make mechanism floating with RigidBodyDynamics](https://discourse.julialang.org/t/unable-to-make-mechanism-floating-with-rigidbodydynamics/72221)

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**Author:** [@bbokser](https://discourse.julialang.org/u/bbokser)\
**Replies:** 1\
**Last updated:** [November 29, 2021, 7:28pm UTC](https://discourse.julialang.org/t/unable-to-make-mechanism-floating-with-rigidbodydynamics/72221 "2021-11-29T19:28:51Z")

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I’m using RigidBodyDynamics and am trying to get my mechanism to be floating rather than fixed-base. However, when I set floating=true in parse\_urdf, I get a “type QuatRotation has no field w” error after running Mechani…

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