# New to Julia

**URL:** https://discourse.julialang.org/c/first-steps/8.md?page=60

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**Page:** 61

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## [Solving system of ODE for updating initial conditions](https://discourse.julialang.org/t/solving-system-of-ode-for-updating-initial-conditions/107784)

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**Author:** [@acubed](https://discourse.julialang.org/u/acubed)\
**Replies:** 7\
**Last updated:** [December 19, 2023, 2:38pm UTC](https://discourse.julialang.org/t/solving-system-of-ode-for-updating-initial-conditions/107784 "2023-12-19T14:38:07Z")

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I am dealing with the following task. I have system of 2nd order ODE which depend on parameter K. I solve this system using DifferentialEquations on time interval \[0,t\_0\], where the value t\_0 is defined. I define tspan a…

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## [Error: curl\_easy\_setopt: 48 with Plots.jl](https://discourse.julialang.org/t/error-curl-easy-setopt-48-with-plots-jl/105171)

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**Author:** [@Alex\_Beck](https://discourse.julialang.org/u/Alex_Beck)\
**Replies:** 10\
**Last updated:** [December 19, 2023, 12:33pm UTC](https://discourse.julialang.org/t/error-curl-easy-setopt-48-with-plots-jl/105171 "2023-12-19T12:33:26Z")

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Hey ! I wanted to use plots for one of my project, but I get this error : ┌ Error: curl\_easy\_setopt: 48 │ │ You may be using an old system libcurl library that doesn't understand options that Julia uses. You can try th…

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## [Anonymous function/comprehension coding](https://discourse.julialang.org/t/anonymous-function-comprehension-coding/107775)

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**Author:** [@SergeantMike](https://discourse.julialang.org/u/SergeantMike)\
**Replies:** 10\
**Last updated:** [December 19, 2023, 11:14am UTC](https://discourse.julialang.org/t/anonymous-function-comprehension-coding/107775 "2023-12-19T11:14:56Z")

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Having a difficult time wrapping my head around Anonymous function and Comprehensions coding, not an easy thing for someone who thinks in ecological terms. What I am doing is doing a life-table calculation for the propo…

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## [Converting a Vector{Vector{String}} to Dict{String, String}](https://discourse.julialang.org/t/converting-a-vector-vector-string-to-dict-string-string/107733)

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**Author:** [@Cortexture](https://discourse.julialang.org/u/Cortexture)\
**Replies:** 6\
**Last updated:** [December 18, 2023, 4:32pm UTC](https://discourse.julialang.org/t/converting-a-vector-vector-string-to-dict-string-string/107733 "2023-12-18T16:32:21Z")

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using Pipe text\_vector = open("../data/exploring\_the\_wonders\_of\_nature.txt") |\> readlines words = replace(text\_vector\[1\], "," =\> "", "." =\> "", "—" =\> " ") |\> split .|\> String cmu\_dat…

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## [How to get the "interior" view of a multidimensional array with unknown number of axes](https://discourse.julialang.org/t/how-to-get-the-interior-view-of-a-multidimensional-array-with-unknown-number-of-axes/107759)

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**Author:** [@jinfreedom](https://discourse.julialang.org/u/jinfreedom)\
**Replies:** 1\
**Last updated:** [December 18, 2023, 10:13am UTC](https://discourse.julialang.org/t/how-to-get-the-interior-view-of-a-multidimensional-array-with-unknown-number-of-axes/107759 "2023-12-18T10:13:11Z")

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Hi, I would like to extract “interior” part of an array A\_int=A\[h:end-h,h:end-h,...\] where I don’t know how many axes A have. What is the correct syntax for this purpose?

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## [Installing Julia on Raspberry Pi 5](https://discourse.julialang.org/t/installing-julia-on-raspberry-pi-5/107694)

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**Author:** [@Alis](https://discourse.julialang.org/u/Alis)\
**Replies:** 3\
**Last updated:** [December 18, 2023, 3:57am UTC](https://discourse.julialang.org/t/installing-julia-on-raspberry-pi-5/107694 "2023-12-18T03:57:39Z")

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Hi all, I can’t seem to get Julia to execute on a Raspberry Pi 5. I’m downloading the AArch64 v1.9.4 release (https://julialang-s3.julialang.org/bin/linux/aarch64/1.9/julia-1.9.4-linux-aarch64.tar.gz). After untarring…

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## [How to augment an \`Int64\` 1-D array or vector](https://discourse.julialang.org/t/how-to-augment-an-int64-1-d-array-or-vector/107729)

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**Author:** [@chandra](https://discourse.julialang.org/u/chandra)\
**Replies:** 8\
**Last updated:** [December 17, 2023, 3:32pm UTC](https://discourse.julialang.org/t/how-to-augment-an-int64-1-d-array-or-vector/107729 "2023-12-17T15:32:55Z")

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function continued\_fraction(num, denom) a = \[\] quo, rem = divrem(num, denom) a0 = quo push!(a, a0) num = denom denom = rem i = 1 while (rem != 0) quo, rem = divrem(num, denom) …

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## [Parameter Estimation of a 3 node thermal network](https://discourse.julialang.org/t/parameter-estimation-of-a-3-node-thermal-network/106232)

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**Author:** [@Sooraj\_Krishnan](https://discourse.julialang.org/u/Sooraj_Krishnan)\
**Replies:** 9\
**Last updated:** [December 17, 2023, 1:14pm UTC](https://discourse.julialang.org/t/parameter-estimation-of-a-3-node-thermal-network/106232 "2023-12-17T13:14:39Z")

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Im trying to formulate a parameter estimation problem to estimate the Resistance and Capacitance values of a 3 node thermal network. The thermal network is in the form of DAE with a mass matrix and exogenous inputs. I al…

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## [Understanding type Ref{T}](https://discourse.julialang.org/t/understanding-type-ref-t/107711)

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**Author:** [@hlbnet](https://discourse.julialang.org/u/hlbnet)\
**Replies:** 9\
**Last updated:** [December 17, 2023, 2:13am UTC](https://discourse.julialang.org/t/understanding-type-ref-t/107711 "2023-12-17T02:13:07Z")

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Hello, I am reading the documentation of the Ref type template: C Interface · The Julia Language Unfortunately, it doesn’t make sense to me. There are a few examples of use of the Ref type, but I hardly see any value o…

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## [What is the role of this word?](https://discourse.julialang.org/t/what-is-the-role-of-this-word/107704)

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**Author:** [@hlbnet](https://discourse.julialang.org/u/hlbnet)\
**Replies:** 2\
**Last updated:** [December 16, 2023, 9:49pm UTC](https://discourse.julialang.org/t/what-is-the-role-of-this-word/107704 "2023-12-16T21:49:11Z")

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Hello, I am very new to Julia. Browsing Julia code implementation, I can see the following construct: """ Some comments here ... """ Foo ... My question is about this single word, here Foo, that is alone on a lin…

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## [The colon punctuation: Why doesn't 5:1 return \[5, 4, 3, 2, 1\]?](https://discourse.julialang.org/t/the-colon-punctuation-why-doesnt-5-1-return-5-4-3-2-1/107676)

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**Author:** [@Tetrakai](https://discourse.julialang.org/u/Tetrakai)\
**Replies:** 8\
**Last updated:** [December 16, 2023, 6:04pm UTC](https://discourse.julialang.org/t/the-colon-punctuation-why-doesnt-5-1-return-5-4-3-2-1/107676 "2023-12-16T18:04:19Z")

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I got surprised by this: julia\> 1:5 # Expected 1:5 julia\> 5:1 # Unexpected 5:4 julia\> collect(1:5) # Expected 5-element Vector{Int64}: 1 2 3 4 5 julia\> collect(5:1) # Doubly Unexpected Int64\[\] julia\> collect(5:…

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## [Impossible to add functional packages in Julia v1.9: Plots, Interact, WebIO](https://discourse.julialang.org/t/impossible-to-add-functional-packages-in-julia-v1-9-plots-interact-webio/107699)

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**Author:** [@Constant31](https://discourse.julialang.org/u/Constant31)\
**Replies:** 6\
**Last updated:** [December 16, 2023, 4:21pm UTC](https://discourse.julialang.org/t/impossible-to-add-functional-packages-in-julia-v1-9-plots-interact-webio/107699 "2023-12-16T16:21:19Z")

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Hello everybody, I’m new on Julia Discourse, used Julia from version 0.6.4, 1.0 and after 1.6.x LTS I tried to jump to one of the last stable versions, so I installed a portable version 1.9. My goal was essentially to…

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## [Integrate Julia scripts into NI Labview](https://discourse.julialang.org/t/integrate-julia-scripts-into-ni-labview/42281)

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**Author:** [@Jonathan\_Israel\_Hern](https://discourse.julialang.org/u/Jonathan_Israel_Hern)\
**Replies:** 10\
**Last updated:** [December 16, 2023, 12:36pm UTC](https://discourse.julialang.org/t/integrate-julia-scripts-into-ni-labview/42281 "2023-12-16T12:36:04Z")

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Hello, how about everyone, my most sincere and cordial greetings to all who read this post. I am a fairly new user and amazed at how great it is to use Julia as an alternative to other languages. My question is a bit s…

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## [My manual Fixed/Random Effects Model perform weirdly](https://discourse.julialang.org/t/my-manual-fixed-random-effects-model-perform-weirdly/107705)

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**Author:** [@Wooheon](https://discourse.julialang.org/u/Wooheon)\
**Replies:** 0\
**Last updated:** [December 16, 2023, 10:13am UTC](https://discourse.julialang.org/t/my-manual-fixed-random-effects-model-perform-weirdly/107705 "2023-12-16T10:13:53Z")

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Hi, I am trying to make manual code for the Fixed/Random Effects model estimation to understand how the process works. However, my manual codes for both models never reject the null for the fake data set. I want to as…

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## [Using print on pi produces π rather than 3.141592653589793](https://discourse.julialang.org/t/using-print-on-pi-produces-rather-than-3-141592653589793/107682)

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**Author:** [@KevinMoerman](https://discourse.julialang.org/u/KevinMoerman)\
**Replies:** 6\
**Last updated:** [December 16, 2023, 12:48am UTC](https://discourse.julialang.org/t/using-print-on-pi-produces-rather-than-3-141592653589793/107682 "2023-12-16T00:48:48Z")

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Is it normal that Julia’s print prints constants as their character or name rather than an interpretation of the numerical value? For instance julia\> print(pi) π Multiply it by something though, e.g. 1, forces the int…

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## [What is the right way to store/record the results of this nested simulation?](https://discourse.julialang.org/t/what-is-the-right-way-to-store-record-the-results-of-this-nested-simulation/107639)

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**Author:** [@Tetrakai](https://discourse.julialang.org/u/Tetrakai)\
**Replies:** 8\
**Last updated:** [December 15, 2023, 4:25pm UTC](https://discourse.julialang.org/t/what-is-the-right-way-to-store-record-the-results-of-this-nested-simulation/107639 "2023-12-15T16:25:49Z")

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I wrote this after seeing the responses to my last question. From the responses I can tell my problem was not understood. What this simulation does is play a rudimentary “game” between pairs of two teams once per “week…

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## [Trying to understand pointers and aliasing](https://discourse.julialang.org/t/trying-to-understand-pointers-and-aliasing/107604)

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**Author:** [@LucasMontoya4](https://discourse.julialang.org/u/LucasMontoya4)\
**Replies:** 5\
**Last updated:** [December 15, 2023, 1:11pm UTC](https://discourse.julialang.org/t/trying-to-understand-pointers-and-aliasing/107604 "2023-12-15T13:11:53Z")

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Hi there, I’m trying to understand what the difference is when you copy elements of an array to another array, vs. setting one equal to another (which results in both just being pointers to the same piece of memory, if I…

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## [Function discovery](https://discourse.julialang.org/t/function-discovery/107652)

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**Author:** [@glebm](https://discourse.julialang.org/u/glebm)\
**Replies:** 3\
**Last updated:** [December 15, 2023, 12:28pm UTC](https://discourse.julialang.org/t/function-discovery/107652 "2023-12-15T12:28:42Z")

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Today I wrote my first program in Julia (solution for Advent of Code 15)! A problem I immediately hit is function discovery. E.g. if have an object x, what can I do with it? In many other languages I type x. and the IDE…

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## [Stuck using backtracking](https://discourse.julialang.org/t/stuck-using-backtracking/107222)

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**Author:** [@bombusfragrans](https://discourse.julialang.org/u/bombusfragrans)\
**Replies:** 2\
**Last updated:** [December 15, 2023, 9:15am UTC](https://discourse.julialang.org/t/stuck-using-backtracking/107222 "2023-12-15T09:15:04Z")

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Hello. To improve my skills I am experimenting with backtracking as a potential approach to solve a verbal arithmetic (alphametics) puzzle. As a starting point I tried to develop a simple implementation of a backtracki…

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## [How do I restrict the number of digits in the REPL display?](https://discourse.julialang.org/t/how-do-i-restrict-the-number-of-digits-in-the-repl-display/107501)

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**Author:** [@chandra](https://discourse.julialang.org/u/chandra)\
**Replies:** 9\
**Last updated:** [December 15, 2023, 3:30am UTC](https://discourse.julialang.org/t/how-do-i-restrict-the-number-of-digits-in-the-repl-display/107501 "2023-12-15T03:30:26Z")

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I wish to restrict the number of significant digits displayed on the REPL according to a context-dependent format like format in MATLAB or Octave. I have looked through the documentation, but have not seen what I am lo…

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## [A problem: writing results to a file in parallel](https://discourse.julialang.org/t/a-problem-writing-results-to-a-file-in-parallel/106172)

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**Author:** [@zhpf0530](https://discourse.julialang.org/u/zhpf0530)\
**Replies:** 14\
**Last updated:** [December 15, 2023, 1:28am UTC](https://discourse.julialang.org/t/a-problem-writing-results-to-a-file-in-parallel/106172 "2023-12-15T01:28:20Z")

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I’m a newbie in julia language, I’ve written a parallel code using Distributed, and I want to write the intermediate results of the program’s calculations to a file, this is my code. using Distributed # Set up p…

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## [How to best preallocate nested tuples of dataframes to store simulation results?](https://discourse.julialang.org/t/how-to-best-preallocate-nested-tuples-of-dataframes-to-store-simulation-results/107543)

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**Author:** [@Tetrakai](https://discourse.julialang.org/u/Tetrakai)\
**Replies:** 31\
**Last updated:** [December 14, 2023, 10:56pm UTC](https://discourse.julialang.org/t/how-to-best-preallocate-nested-tuples-of-dataframes-to-store-simulation-results/107543 "2023-12-14T22:56:13Z")

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I’m trying to run some sport game simulations and programmatically store the results in the most efficient manner. Even if not strictly necessary for my purpose, I am trying to learn how to do right. Right now my order …

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## [Plots, InitError GR\_jll not defined](https://discourse.julialang.org/t/plots-initerror-gr-jll-not-defined/107633)

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**Author:** [@hilbertstraum](https://discourse.julialang.org/u/hilbertstraum)\
**Replies:** 0\
**Last updated:** [December 14, 2023, 9:25pm UTC](https://discourse.julialang.org/t/plots-initerror-gr-jll-not-defined/107633 "2023-12-14T21:25:32Z")

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Hi, im new to Julia and wanted to try out some plotting with the Plots-Package. Did run into similar problems as: or: but the solution did not work out for me. I got the GR.plot(rand(10)) to work, but “using Plots…

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## [Change the values in colorbar to cover all values](https://discourse.julialang.org/t/change-the-values-in-colorbar-to-cover-all-values/107603)

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**Author:** [@quantum](https://discourse.julialang.org/u/quantum)\
**Replies:** 0\
**Last updated:** [December 14, 2023, 9:07am UTC](https://discourse.julialang.org/t/change-the-values-in-colorbar-to-cover-all-values/107603 "2023-12-14T09:07:40Z")

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I am new to python and Julia. I want add a color bar to a scatter plot. But the values of colorbar just cover one group of points. How can I change the color bar to cover all the values? My code attached. fig, ax = PyPl…

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## [What functions are visible in REPL?](https://discourse.julialang.org/t/what-functions-are-visible-in-repl/107612)

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**Author:** [@jiang\_ming\_zhang](https://discourse.julialang.org/u/jiang_ming_zhang)\
**Replies:** 3\
**Last updated:** [December 14, 2023, 3:30pm UTC](https://discourse.julialang.org/t/what-functions-are-visible-in-repl/107612 "2023-12-14T15:30:45Z")

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I am using some people’s package. I tried to look up some function in the REPL with ?. But it turned that the function could not be found. The function is definitely there in the package. Is it because the function is …

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## [Circshift() shifts array in opposite direction to circshift!()](https://discourse.julialang.org/t/circshift-shifts-array-in-opposite-direction-to-circshift/107584)

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**Author:** [@LucasMontoya4](https://discourse.julialang.org/u/LucasMontoya4)\
**Replies:** 14\
**Last updated:** [December 13, 2023, 9:46pm UTC](https://discourse.julialang.org/t/circshift-shifts-array-in-opposite-direction-to-circshift/107584 "2023-12-13T21:46:13Z")

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Hi there, I have written the following little code in Julia 1.8 to try to figure out a bug. I’m trying to simulate periodic boundary conditions, and hence using the circshift function. But for some reason, it seems like…

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## [Which algorithm does Julia use for matrix QR decomposition?](https://discourse.julialang.org/t/which-algorithm-does-julia-use-for-matrix-qr-decomposition/107566)

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**Author:** [@boywithacoin](https://discourse.julialang.org/u/boywithacoin)\
**Replies:** 5\
**Last updated:** [December 13, 2023, 8:04pm UTC](https://discourse.julialang.org/t/which-algorithm-does-julia-use-for-matrix-qr-decomposition/107566 "2023-12-13T20:04:01Z")

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Which algorithm does Julia uses for QR decomposition? Additionally, parallelizing decomposition methods is non-trivial. Does it use a specialized implementation on the GPU?

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## [Trouble translating some dplyr code to DataFramesMeta](https://discourse.julialang.org/t/trouble-translating-some-dplyr-code-to-dataframesmeta/107555)

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**Author:** [@wasser\_m](https://discourse.julialang.org/u/wasser_m)\
**Replies:** 2\
**Last updated:** [December 13, 2023, 5:28pm UTC](https://discourse.julialang.org/t/trouble-translating-some-dplyr-code-to-dataframesmeta/107555 "2023-12-13T17:28:58Z")

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I’m quite new to DataFrames and tried to translate some of my R code to Julia. Here is my R code: df |\> left\_join(df2, by="customer") |\> left\_join(df3, by="order") |\> left\_join(df4, by="item") |\> group\_by(order…

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## [How do I fix this error I got when trying the first FastAI example?](https://discourse.julialang.org/t/how-do-i-fix-this-error-i-got-when-trying-the-first-fastai-example/106586)

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**Author:** [@Tetrakai](https://discourse.julialang.org/u/Tetrakai)\
**Replies:** 4\
**Last updated:** [December 13, 2023, 3:58pm UTC](https://discourse.julialang.org/t/how-do-i-fix-this-error-i-got-when-trying-the-first-fastai-example/106586 "2023-12-13T15:58:21Z")

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I tried the example in the readme: using FastAI, FastVision data, blocks = load(datarecipes()\["imagenette2-320"\]) task = ImageClassificationSingle(blocks) learner = tasklearner(task, data, callbacks=\[ToGPU()\]) fitonecyc…

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## [Broadcasting slower than for-loop](https://discourse.julialang.org/t/broadcasting-slower-than-for-loop/107562)

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**Author:** [@Matthijs\_1971](https://discourse.julialang.org/u/Matthijs_1971)\
**Replies:** 6\
**Last updated:** [December 13, 2023, 2:16pm UTC](https://discourse.julialang.org/t/broadcasting-slower-than-for-loop/107562 "2023-12-13T14:16:39Z")

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There has been some discussion on several fora on the speed of broadcasting vs. a for loop - some aspects escape me. The output of the Julia script below: Explicit for loop: 1.310 μs (0 allocations: 0 bytes) 1.309 μ…

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