# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1296

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

**Page:** 1297

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## [Placing a label at an arbitrary place using Gadfly](https://discourse.julialang.org/t/placing-a-label-at-an-arbitrary-place-using-gadfly/66528)

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**Author:** [@devin](https://discourse.julialang.org/u/devin)\
**Replies:** 3\
**Last updated:** [August 17, 2021, 9:39pm UTC](https://discourse.julialang.org/t/placing-a-label-at-an-arbitrary-place-using-gadfly/66528 "2021-08-17T21:39:23Z")

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I’m trying to place a label at any arbitrary (x,y) location in my plot, but I can’t quite figure it out. Here’s my code: t = 0.001:0.001:2 f = 25.0 y = cos.(2.0 \* π \* f .\* t); p = plot(x=t\[1:100\], y=y\[1:100\], Geom.line…

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## [Connection between sensitivity algorithm and gradient calculation of the loss function](https://discourse.julialang.org/t/connection-between-sensitivity-algorithm-and-gradient-calculation-of-the-loss-function/66550)

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**Author:** [@hardy](https://discourse.julialang.org/u/hardy)\
**Replies:** 6\
**Last updated:** [August 17, 2021, 9:22pm UTC](https://discourse.julialang.org/t/connection-between-sensitivity-algorithm-and-gradient-calculation-of-the-loss-function/66550 "2021-08-17T21:22:31Z")

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I’m new to Julia and ML and try to understand the basics. I have defined an ODE problem with 2 parameters. This is used for the prediction in my loss function. This loss function is now used in turn to optimize the para…

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## [22 seconds to 3 and now more: Let's fix all of the DifferentialEquations.jl + universe compile times!](https://discourse.julialang.org/t/22-seconds-to-3-and-now-more-lets-fix-all-of-the-differentialequations-jl-universe-compile-times/66313)

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**Author:** [@ChrisRackauckas](https://discourse.julialang.org/u/ChrisRackauckas)\
**Replies:** 6\
**Last updated:** [August 17, 2021, 9:18pm UTC](https://discourse.julialang.org/t/22-seconds-to-3-and-now-more-lets-fix-all-of-the-differentialequations-jl-universe-compile-times/66313 "2021-08-17T21:18:50Z")

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These are the JuliaCon hackathon results for SciML compile time issues, with major help from @tim.holy (and more to be announced soon…). This is a repost of 22 seconds to 3 and now more: Let's fix all of the Differential…

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## [Exception after package updates](https://discourse.julialang.org/t/exception-after-package-updates/66568)

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**Author:** [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Replies:** 1\
**Last updated:** [August 17, 2021, 8:39pm UTC](https://discourse.julialang.org/t/exception-after-package-updates/66568 "2021-08-17T20:39:57Z")

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After updating the packages used by my project I get the following exception: julia\> using RTSim julia\> init\_sim(5.0) ERROR: MethodError: no method matching residual!(::Vector{Float64}, ::StaticArrays.SizedVector{36, F…

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## [IO write/read \<strlen\> \<string\>](https://discourse.julialang.org/t/io-write-read-strlen-string/66362)

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**Author:** [@Bardo](https://discourse.julialang.org/u/Bardo)\
**Replies:** 15\
**Last updated:** [August 17, 2021, 8:24pm UTC](https://discourse.julialang.org/t/io-write-read-strlen-string/66362 "2021-08-17T20:24:27Z")

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With the suggestions below: # write number as type T function writenum(io, num, T) write(io, T(num)) end # read n numbers of type T function readnum(io, T, n) s = sizeof(T) f = zeros(UInt8, s\*n) readbyte…

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## [MethodError: no method matching in JuMP](https://discourse.julialang.org/t/methoderror-no-method-matching-in-jump/66543)

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**Author:** [@zhangsanle](https://discourse.julialang.org/u/zhangsanle)\
**Replies:** 1\
**Last updated:** [August 17, 2021, 8:09pm UTC](https://discourse.julialang.org/t/methoderror-no-method-matching-in-jump/66543 "2021-08-17T20:09:34Z")

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I am new in julia. When i use JuMP, i meet some problems: MethodError: no method matching (::Interpolations.Extrapolation{Float64, 1, ScaledInterpolation{Float64, 1, Interpolations.BSplineInterpolation{Float64, 1, Vector…

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## [VScode Julia REPL "path" issue (while bash works fine)](https://discourse.julialang.org/t/vscode-julia-repl-path-issue-while-bash-works-fine/66023)

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**Author:** [@SingingKim](https://discourse.julialang.org/u/SingingKim)\
**Replies:** 3\
**Last updated:** [August 17, 2021, 7:53pm UTC](https://discourse.julialang.org/t/vscode-julia-repl-path-issue-while-bash-works-fine/66023 "2021-08-17T19:53:28Z")

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Hi all, I’m trying to use the Julia REPL but having a library path problem. Oddly, the same code works just fine with bash/terminal (right-hand side), but an error occurs with REPL (left-hand side): Can anyone let me …

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## [Possible DNSSEC issue](https://discourse.julialang.org/t/possible-dnssec-issue/66526)

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**Author:** [@Ross\_Boylan](https://discourse.julialang.org/u/Ross_Boylan)\
**Replies:** 1\
**Last updated:** [August 17, 2021, 7:50pm UTC](https://discourse.julialang.org/t/possible-dnssec-issue/66526 "2021-08-17T19:50:49Z")

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I am unable to get DNS lookups for docs.julialang.org. My DNS server says 16-Aug-2021 16:18:33.166 lame-servers: info: no valid DS resolving docs.julialang.org/DS/IN': 198.144.192.4#53 and DNSSEC Analyzer - docs.julial…

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## [Simplify an equality](https://discourse.julialang.org/t/simplify-an-equality/66562)

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**Author:** [@fms-1988](https://discourse.julialang.org/u/fms-1988)\
**Replies:** 1\
**Last updated:** [August 17, 2021, 6:42pm UTC](https://discourse.julialang.org/t/simplify-an-equality/66562 "2021-08-17T18:42:09Z")

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I have the following equality: \\frac{x+y}{a}=0 I want to simplify this equality, ie: x = -y I’m trying the following code, but without success: using SymPy x,y,a = symbols("x,y,a") eq1 = Eq((x+y)/a,0) simplify(eq1)

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## [Your opinion on use of Julia in PhD](https://discourse.julialang.org/t/your-opinion-on-use-of-julia-in-phd/66062)

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**Author:** [@Inna](https://discourse.julialang.org/u/Inna)\
**Replies:** 35\
**Last updated:** [August 17, 2021, 6:16pm UTC](https://discourse.julialang.org/t/your-opinion-on-use-of-julia-in-phd/66062 "2021-08-17T18:16:58Z")

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Hello, I am searching for PhD programs on Atmospheric Sciences and i can see that the most prefer/require knowledge of Python but almost no one refers to Julia. From your experience on PhD, it would be a problem in my …

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## [Reducing GC time in loop using FLoops.jl](https://discourse.julialang.org/t/reducing-gc-time-in-loop-using-floops-jl/66534)

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**Author:** [@beeswax](https://discourse.julialang.org/u/beeswax)\
**Replies:** 2\
**Last updated:** [August 17, 2021, 4:14pm UTC](https://discourse.julialang.org/t/reducing-gc-time-in-loop-using-floops-jl/66534 "2021-08-17T16:14:25Z")

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I’m trying to speed up the runtime of a back-projection image formation algorithm for SAR and want to see how far things can be pushed for the naive version using parallel computing and the speed of Julia (I’m aware that…

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## [Faster \`min\`,\`max\` for \`Float64|32\`](https://discourse.julialang.org/t/faster-min-max-for-float64-32/45464)

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**Author:** [@JeffreySarnoff](https://discourse.julialang.org/u/JeffreySarnoff)\
**Replies:** 38\
**Last updated:** [August 17, 2021, 12:25pm UTC](https://discourse.julialang.org/t/faster-min-max-for-float64-32/45464 "2021-08-17T12:25:14Z")

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These realizations have simpler native code structure and benchmark faster than the current versions. These implementations may be IEEE754 compliant. const FastFloat = Union{Float32, Float64} function min(a::T, b::T) …

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## [Pixel buffer objects](https://discourse.julialang.org/t/pixel-buffer-objects/66557)

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**Author:** [@Jakub\_Mitura](https://discourse.julialang.org/u/Jakub_Mitura)\
**Replies:** 0\
**Last updated:** [August 17, 2021, 3:33pm UTC](https://discourse.julialang.org/t/pixel-buffer-objects/66557 "2021-08-17T15:33:31Z")

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Hello I am trying to implement OpenGl pixel buffer object, becouse fast upload of data to texture is critical for my use case. My code that tries to implement it (using ModernGl.jl) juliaDataType= UInt8 toSend = ones…

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## [Sometimes CompatHelper 3 is not available](https://discourse.julialang.org/t/sometimes-compathelper-3-is-not-available/66556)

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**Author:** [@zsunberg](https://discourse.julialang.org/u/zsunberg)\
**Replies:** 0\
**Last updated:** [August 17, 2021, 3:32pm UTC](https://discourse.julialang.org/t/sometimes-compathelper-3-is-not-available/66556 "2021-08-17T15:32:57Z")

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I have installed CompatHelper with a version 3 requirement as suggested in the CompatHelper repository. However, a significant percentage of the time, the job fails because only Compat Helper versions 0.1.0-2.1.1 are ava…

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## [DataFrames: where is categorical?](https://discourse.julialang.org/t/dataframes-where-is-categorical/66555)

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**Author:** [@PetrKryslUCSD](https://discourse.julialang.org/u/PetrKryslUCSD)\
**Replies:** 1\
**Last updated:** [August 17, 2021, 3:27pm UTC](https://discourse.julialang.org/t/dataframes-where-is-categorical/66555 "2021-08-17T15:27:57Z")

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This is confusing: categorical should be available in 1.2.2? (@v1.8) pkg\> st …

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## [New To Julia: How to get 2 values from dataset](https://discourse.julialang.org/t/new-to-julia-how-to-get-2-values-from-dataset/66553)

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**Author:** [@atplf](https://discourse.julialang.org/u/atplf)\
**Replies:** 3\
**Last updated:** [August 17, 2021, 3:17pm UTC](https://discourse.julialang.org/t/new-to-julia-how-to-get-2-values-from-dataset/66553 "2021-08-17T15:17:06Z")

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I have df like this: How can I get values from “\<=50K” and “\>50K” of “19-30”, “41-50”. And then i want to make a group bar from 2 values. Anyone can answer me this question. Thank you so much

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## [Julia Beginner: How to create grouped variable in julia](https://discourse.julialang.org/t/julia-beginner-how-to-create-grouped-variable-in-julia/66547)

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**Author:** [@atplf](https://discourse.julialang.org/u/atplf)\
**Replies:** 3\
**Last updated:** [August 17, 2021, 1:45pm UTC](https://discourse.julialang.org/t/julia-beginner-how-to-create-grouped-variable-in-julia/66547 "2021-08-17T13:45:51Z")

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I have a column of age values from dataset that I need to convert to age ranges of 18-29, 30-39, 40-49, 50-59, 60-69, and 70+: and i want it like this: Anyone can help me. Thanks

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## [Reduce memory allocation in copying array](https://discourse.julialang.org/t/reduce-memory-allocation-in-copying-array/66536)

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**Author:** [@Frisus95](https://discourse.julialang.org/u/Frisus95)\
**Replies:** 6\
**Last updated:** [August 17, 2021, 1:04pm UTC](https://discourse.julialang.org/t/reduce-memory-allocation-in-copying-array/66536 "2021-08-17T13:04:12Z")

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Hello everyone. I was wondering if there is a way to reduce the memory allocation of a code like this: julia\> function funza(N) a = Array{Float64}(undef,5) b = Array{Float64}(undef,5) for…

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## [Improving function performance - Broadcasting vs Loops](https://discourse.julialang.org/t/improving-function-performance-broadcasting-vs-loops/66537)

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**Author:** [@jpmorr](https://discourse.julialang.org/u/jpmorr)\
**Replies:** 14\
**Last updated:** [August 17, 2021, 1:02pm UTC](https://discourse.julialang.org/t/improving-function-performance-broadcasting-vs-loops/66537 "2021-08-17T13:02:57Z")

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I’m slowly learning some of the tricks that can make julia code quicker. Coming from python I still find it strange to write a loop instead of some vectorised but it seems that sometimes that the loop is the quicker opti…

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## [Color gradient by factor in StatsPlots](https://discourse.julialang.org/t/color-gradient-by-factor-in-statsplots/30704)

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**Author:** [@Christopher\_Fisher](https://discourse.julialang.org/u/Christopher_Fisher)\
**Replies:** 9\
**Last updated:** [August 17, 2021, 1:02pm UTC](https://discourse.julialang.org/t/color-gradient-by-factor-in-statsplots/30704 "2021-08-17T13:02:08Z")

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Hi all- I would like to use a gradient to color code lines based on values of a factor. In the example below, I would like the two groups of lines to have the same colors based on the slopes. How do I do that? using Da…

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## [Parametered optional named arguments](https://discourse.julialang.org/t/parametered-optional-named-arguments/66541)

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**Author:** [@Philippe\_Maincon1](https://discourse.julialang.org/u/Philippe_Maincon1)\
**Replies:** 3\
**Last updated:** [August 17, 2021, 11:36am UTC](https://discourse.julialang.org/t/parametered-optional-named-arguments/66541 "2021-08-17T11:36:18Z")

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When I call the function function f(; field ::NTuple{Nfield,Symbol}, fieldscale ::NTuple= (),#NTuple{Nfield ,Float64}(1. for i =1: Nfield), afield ::NTuple{Nafield,Symbol}=(;), afieldscale…

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## [BenchmarkGallery?](https://discourse.julialang.org/t/benchmarkgallery/66542)

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**Author:** [@SteffenPL](https://discourse.julialang.org/u/SteffenPL)\
**Replies:** 1\
**Last updated:** [August 17, 2021, 11:24am UTC](https://discourse.julialang.org/t/benchmarkgallery/66542 "2021-08-17T11:24:40Z")

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I thought about collecting Julia code snippets and sort and assemble them into a public git repository. Does something like this already exist? I’m happy to start something, but before I do so, ideas would be very wel…

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## [Juliapro curated packages](https://discourse.julialang.org/t/juliapro-curated-packages/66539)

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**Author:** [@Ogweno\_Emmanuel](https://discourse.julialang.org/u/Ogweno_Emmanuel)\
**Replies:** 2\
**Last updated:** [August 17, 2021, 11:10am UTC](https://discourse.julialang.org/t/juliapro-curated-packages/66539 "2021-08-17T11:10:52Z")

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Are the Juliapro curated packages only available to Juliapro users? I’ve tried downloading Juliapro and I get a screen with a lot of symbols I don’t understand which finally goes blank and says an error occurred.

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## [How to convert a JPEG image (from mobile) to a stantard 60k Array{ColorTypes.Gray{FixedPointNumbers.Normed{UInt8, 8}}, 2}) (from Flux.Data.MNIST)?](https://discourse.julialang.org/t/how-to-convert-a-jpeg-image-from-mobile-to-a-stantard-60k-array-colortypes-gray-fixedpointnumbers-normed-uint8-8-2-from-flux-data-mnist/66475)

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**Author:** [@sylvaticus](https://discourse.julialang.org/u/sylvaticus)\
**Replies:** 5\
**Last updated:** [August 17, 2021, 10:20am UTC](https://discourse.julialang.org/t/how-to-convert-a-jpeg-image-from-mobile-to-a-stantard-60k-array-colortypes-gray-fixedpointnumbers-normed-uint8-8-2-from-flux-data-mnist/66475 "2021-08-17T10:20:15Z")

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For an exercise I want to let students draw their own digits, scan them with a mobile and let a MINST-trained flux NN to category them. I see that the single MINST images are of type Matrix{ColorTypes.Gray{FixedPointNum…

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## [Object Detection in Julia](https://discourse.julialang.org/t/object-detection-in-julia/65115)

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**Author:** [@ppkvm](https://discourse.julialang.org/u/ppkvm)\
**Replies:** 6\
**Last updated:** [August 17, 2021, 10:17am UTC](https://discourse.julialang.org/t/object-detection-in-julia/65115 "2021-08-17T10:17:35Z")

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I would like to see examples of Object Detection using YOLO and SSD implemented in Julia. Has anyone tried this before?

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## [Smarter, or at least less verbose, tab/auto completion.. using tools?](https://discourse.julialang.org/t/smarter-or-at-least-less-verbose-tab-auto-completion-using-tools/66529)

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**Author:** [@eo1989](https://discourse.julialang.org/u/eo1989)\
**Replies:** 0\
**Last updated:** [August 17, 2021, 2:45am UTC](https://discourse.julialang.org/t/smarter-or-at-least-less-verbose-tab-auto-completion-using-tools/66529 "2021-08-17T02:45:56Z")

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I use Julia REPL quite often and really enjoy the unicode completion a lot. That being said, Is it possible to incorporate FZF’s selection feature into tab completion? I understand OhMyREPL already uses fzf (or at least …

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## [A simple but mystifying package conflict message](https://discourse.julialang.org/t/a-simple-but-mystifying-package-conflict-message/66519)

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**Author:** [@ablaom](https://discourse.julialang.org/u/ablaom)\
**Replies:** 2\
**Last updated:** [August 17, 2021, 2:33am UTC](https://discourse.julialang.org/t/a-simple-but-mystifying-package-conflict-message/66519 "2021-08-17T02:33:59Z")

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I thought I had the hang of understanding pkg conflict messages, but this one has me stumped. I have an env with just one package. That package, NaiveBayes, has this \[compat\] entry for Distributions: Distributions = "0…

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## [How to test \`jldoctest\` block for errors, but nothing else](https://discourse.julialang.org/t/how-to-test-jldoctest-block-for-errors-but-nothing-else/66491)

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**Author:** [@Torkel](https://discourse.julialang.org/u/Torkel)\
**Replies:** 3\
**Last updated:** [August 16, 2021, 10:10pm UTC](https://discourse.julialang.org/t/how-to-test-jldoctest-block-for-errors-but-nothing-else/66491 "2021-08-16T22:10:00Z")

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I am making doctests for a package (Catalyst.jl) using Documenter. There are many blocks that returns a big mess of output (not displayed), which is stochastic or pseudo-stochastic. An example would be using DiffEqJump …

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## [Question on QSIR Model and Flux.train for COVID-19 SIR data](https://discourse.julialang.org/t/question-on-qsir-model-and-flux-train-for-covid-19-sir-data/66422)

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**Author:** [@msteele-uofa-ece](https://discourse.julialang.org/u/msteele-uofa-ece)\
**Replies:** 3\
**Last updated:** [August 16, 2021, 9:33pm UTC](https://discourse.julialang.org/t/question-on-qsir-model-and-flux-train-for-covid-19-sir-data/66422 "2021-08-16T21:33:32Z")

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Hello, My name is Manuel Steele. I am a graduate student at St. Mary’s College for data science (Notre Dame, IN). I applied the model at the github site below to a smaller county in North Dakota. The model was succes…

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## [Why does julia use thousands of cpu-hours to compute 1+2?](https://discourse.julialang.org/t/why-does-julia-use-thousands-of-cpu-hours-to-compute-1-2/66041)

<div class="topic-metadata">

**Author:** [@moble](https://discourse.julialang.org/u/moble)\
**Replies:** 10\
**Last updated:** [August 16, 2021, 9:03pm UTC](https://discourse.julialang.org/t/why-does-julia-use-thousands-of-cpu-hours-to-compute-1-2/66041 "2021-08-16T21:03:15Z")

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I’m fairly new to julia, and not overly experienced with scaling to huge numbers of processes, so forgive me if I’m missing something obvious. Alright, to be honest, I actually used a couple thousand cpu-hours to run us…

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