# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1070

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

**Page:** 1071

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## [Running commands over ssh](https://discourse.julialang.org/t/running-commands-over-ssh/27103)

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**Author:** [@jw3126](https://discourse.julialang.org/u/jw3126)\
**Replies:** 8\
**Last updated:** [April 12, 2022, 7:35am UTC](https://discourse.julialang.org/t/running-commands-over-ssh/27103 "2022-04-12T07:35:15Z")

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I would like to run commands from julia over ssh. I know how to do this in an ad hoc way: Cmd(\`ssh user@remote 'ls'\`) However I wonder is there a way to use the full power of julia command running over ssh? That is I …

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## [Word Cloud of Scientific Computing Languages](https://discourse.julialang.org/t/word-cloud-of-scientific-computing-languages/79319)

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**Author:** [@nharr](https://discourse.julialang.org/u/nharr)\
**Replies:** 2\
**Last updated:** [April 12, 2022, 7:04am UTC](https://discourse.julialang.org/t/word-cloud-of-scientific-computing-languages/79319 "2022-04-12T07:04:47Z")

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Hello community. I need some help. I believe I once watched a youtube video where @viralbshah showed a word cloud of common languages used for scientific computing. I’m specifically wanting to use such a word cloud in an…

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## [Suggestions on model and solvers](https://discourse.julialang.org/t/suggestions-on-model-and-solvers/79345)

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**Author:** [@Patrik\_Waldmann](https://discourse.julialang.org/u/Patrik_Waldmann)\
**Replies:** 3\
**Last updated:** [April 12, 2022, 4:47am UTC](https://discourse.julialang.org/t/suggestions-on-model-and-solvers/79345 "2022-04-12T04:47:36Z")

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I would be happy for suggestions on how and where to implement the model for the data below (the plan is to extend to a much larger data set later so speed is of interest): #Toy data A = \[1.0000 0 0.5000 0.5000 0.4714 0…

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## [Apply blockdiag function over an array of matrices](https://discourse.julialang.org/t/apply-blockdiag-function-over-an-array-of-matrices/79366)

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**Author:** [@ahmed](https://discourse.julialang.org/u/ahmed)\
**Replies:** 1\
**Last updated:** [April 12, 2022, 4:33am UTC](https://discourse.julialang.org/t/apply-blockdiag-function-over-an-array-of-matrices/79366 "2022-04-12T04:33:59Z")

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I have an array of sparse matrices that I’d like to put into block-diagonal form. The syntax for the “blockdiag” function is like: blockdiag(A,B,C) where A, B and C are sparse matrices. My array is quite large so I can’…

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## [Julia versus MATLAB](https://discourse.julialang.org/t/julia-versus-matlab/79360)

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**Author:** [@kumarbalachandran](https://discourse.julialang.org/u/kumarbalachandran)\
**Replies:** 5\
**Last updated:** [April 12, 2022, 2:12am UTC](https://discourse.julialang.org/t/julia-versus-matlab/79360 "2022-04-12T02:12:56Z")

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I am trying Julia 1.7.2 on an M1 MacBook Air for bench marking Eigen against MATLAB 2022a a=randn(100,100) tic, for x=1:100; eig(a); end; toc Elapsed time is 0.295766 seconds. whereas Julia v1.7.2 a=randn(Float64, (10…

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## [Custom Flux.jl loss function with Interpolations.jl evaluation Error](https://discourse.julialang.org/t/custom-flux-jl-loss-function-with-interpolations-jl-evaluation-error/79305)

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**Author:** [@StefanBerger](https://discourse.julialang.org/u/StefanBerger)\
**Replies:** 3\
**Last updated:** [April 12, 2022, 12:21am UTC](https://discourse.julialang.org/t/custom-flux-jl-loss-function-with-interpolations-jl-evaluation-error/79305 "2022-04-12T00:21:10Z")

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Hello, I am trying to implement a model with a custom loss function in the Flux.jl package. I include the code for a simplified model, but the error stays the same. I have an interpolator which takes a scalar value and…

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## [Intersection of two rotated rectangles?](https://discourse.julialang.org/t/intersection-of-two-rotated-rectangles/79312)

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**Author:** [@vshesh](https://discourse.julialang.org/u/vshesh)\
**Replies:** 6\
**Last updated:** [April 12, 2022, 12:20am UTC](https://discourse.julialang.org/t/intersection-of-two-rotated-rectangles/79312 "2022-04-12T00:20:26Z")

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Is there a julia implemented version of deciding whether two rects intersect? rects are rotated about their top left corner, specified as \[x, y, width, height, angle\] so for example: \> collision(\[0,0,100,100,0\], \[40,4…

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## [macOS: ARM vs Intel](https://discourse.julialang.org/t/macos-arm-vs-intel/79337)

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**Author:** [@amrods](https://discourse.julialang.org/u/amrods)\
**Replies:** 6\
**Last updated:** [April 11, 2022, 11:12pm UTC](https://discourse.julialang.org/t/macos-arm-vs-intel/79337 "2022-04-11T23:12:49Z")

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I recently obtained access to a newer Mac computer with ARM processor. Is there some ready to use benchmark I can execute to see if running native ARM Julia will be faster (and safe) vs running Julia x86 on ARM through R…

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## [Pre-allocated eigen value decomposition](https://discourse.julialang.org/t/pre-allocated-eigen-value-decomposition/79358)

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**Author:** [@jinml](https://discourse.julialang.org/u/jinml)\
**Replies:** 2\
**Last updated:** [April 11, 2022, 10:07pm UTC](https://discourse.julialang.org/t/pre-allocated-eigen-value-decomposition/79358 "2022-04-11T22:07:07Z")

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Is there a way to pre-allocate an array to hold the returned eigenvalues and vectors from eigen or eigen! ? Currently both functions return a factorization which does not seem to allow a pre-allocation. The following cod…

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## [Setting nonlinear objectives with JuMP](https://discourse.julialang.org/t/setting-nonlinear-objectives-with-jump/79343)

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**Author:** [@Hans\_W\_Borchers](https://discourse.julialang.org/u/Hans_W_Borchers)\
**Replies:** 4\
**Last updated:** [April 11, 2022, 7:59pm UTC](https://discourse.julialang.org/t/setting-nonlinear-objectives-with-jump/79343 "2022-04-11T19:59:18Z")

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Dear All, one year ago I have written a small note on how to use Julia from R through the ‘JuliaCall’ package. I wanted to update this page and encountered some problems with Julia’s JuMP package. See Notes on JuliaCall…

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## [Simple Flux LSTM for Time Series](https://discourse.julialang.org/t/simple-flux-lstm-for-time-series/35494)

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**Author:** [@compleat](https://discourse.julialang.org/u/compleat)\
**Replies:** 62\
**Last updated:** [April 11, 2022, 7:02pm UTC](https://discourse.julialang.org/t/simple-flux-lstm-for-time-series/35494 "2022-04-11T19:02:45Z")

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Hi, I have been trying for a long time to get Flux working for a basic time series. I think if I can get a really simple example working, I would be able to go from there, but when I try to do the ‘obvious’ thing, it fa…

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## [Julia is very slow compared to python/numpy. What am I doing wrong here?](https://discourse.julialang.org/t/julia-is-very-slow-compared-to-python-numpy-what-am-i-doing-wrong-here/78598)

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**Author:** [@Vahid\_Hosseinzadeh](https://discourse.julialang.org/u/Vahid_Hosseinzadeh)\
**Replies:** 25\
**Last updated:** [April 11, 2022, 6:41pm UTC](https://discourse.julialang.org/t/julia-is-very-slow-compared-to-python-numpy-what-am-i-doing-wrong-here/78598 "2022-04-11T18:41:34Z")

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Hi guys, I wrote a recursive function which construct a matrix in python using Qutip module: (I just used the tensor function and Pauli matrices definitions from Qutip) import numpy as np from qutip import \* def psit…

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## [Formatting/converting Matrix{Char} into Vector{String}](https://discourse.julialang.org/t/formatting-converting-matrix-char-into-vector-string/79224)

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**Author:** [@gltchr](https://discourse.julialang.org/u/gltchr)\
**Replies:** 8\
**Last updated:** [April 11, 2022, 6:20pm UTC](https://discourse.julialang.org/t/formatting-converting-matrix-char-into-vector-string/79224 "2022-04-11T18:20:00Z")

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Hello, I am writing some simple wrappers around an old C library. I am new to Julia and absolutely new to C, so it might be something obvious. I have managed to get majority of functions working, but I am unsure about …

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## [Compare 2 data sets - similar to SAS proc compare](https://discourse.julialang.org/t/compare-2-data-sets-similar-to-sas-proc-compare/79215)

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**Author:** [@ab2z](https://discourse.julialang.org/u/ab2z)\
**Replies:** 4\
**Last updated:** [April 11, 2022, 6:02pm UTC](https://discourse.julialang.org/t/compare-2-data-sets-similar-to-sas-proc-compare/79215 "2022-04-11T18:02:38Z")

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Question: what is the best command for comparing 2 datasets - something like proc compare in SAS ? I could not edit this Comparison 2 data sets , So I decide to open this new topic. I have the following example old=Da…

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## [What’s stopping Julia from using Boolean values as Singleton types?](https://discourse.julialang.org/t/what-s-stopping-julia-from-using-boolean-values-as-singleton-types/78898)

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**Author:** [@cadojo](https://discourse.julialang.org/u/cadojo)\
**Replies:** 15\
**Last updated:** [April 11, 2022, 4:41pm UTC](https://discourse.julialang.org/t/what-s-stopping-julia-from-using-boolean-values-as-singleton-types/78898 "2022-04-11T16:41:29Z")

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To keep type stability for functions with conditional arguments, folks often write branches like… if arg == Val{true} return A else return B end What would be the downside of making a special case for boolean v…

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## [Safe Usage of UnsafeArrays](https://discourse.julialang.org/t/safe-usage-of-unsafearrays/79285)

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**Author:** [@cortner](https://discourse.julialang.org/u/cortner)\
**Replies:** 2\
**Last updated:** [April 11, 2022, 3:13pm UTC](https://discourse.julialang.org/t/safe-usage-of-unsafearrays/79285 "2022-04-11T15:13:28Z")

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Is the following a “safe” usage of \`UnsafeArrays? struct SafeUnsafeArray{T, N} \<: AbstractArray{T, N} A::UnsafeArray{T, N} \_A::Vector{UInt8} end x = zeros(UInt8, 800) ptr = Base.unsafe\_convert(Ptr{Float64}, x) u …

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## [🎈 Pluto Event #1: Plotting Barcamp](https://discourse.julialang.org/t/pluto-event-1-plotting-barcamp/78387)

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**Author:** [@fonsp](https://discourse.julialang.org/u/fonsp)\
**Replies:** 3\
**Last updated:** [April 11, 2022, 2:58pm UTC](https://discourse.julialang.org/t/pluto-event-1-plotting-barcamp/78387 "2022-04-11T14:58:20Z")

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Pluto Event #1: Plotting Barcamp Last year, we organized PlutoCon 2021, and we loved seeing all the ways that people use Pluto! This year, we want to focus on this aspect, and we want to enable you, the community, to mee…

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## [Discrepency related to using \`\`\`lyapunovspectrum\`\`\` from DynamicalSystems.jl package](https://discourse.julialang.org/t/discrepency-related-to-using-lyapunovspectrum-from-dynamicalsystems-jl-package/75453)

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**Author:** [@pafloxy](https://discourse.julialang.org/u/pafloxy)\
**Replies:** 9\
**Last updated:** [April 11, 2022, 2:53pm UTC](https://discourse.julialang.org/t/discrepency-related-to-using-lyapunovspectrum-from-dynamicalsystems-jl-package/75453 "2022-04-11T14:53:07Z")

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Hi! I was trying out the lyapunovspectrum function in Julia, for a few standard dynamical systems like Rossler. I compared the results obtained by using lyapunovspectrum to the spectrum obtained by manually initiating a…

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## [Alternatives to \`Base.hash\`?](https://discourse.julialang.org/t/alternatives-to-base-hash/79154)

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**Author:** [@jw3126](https://discourse.julialang.org/u/jw3126)\
**Replies:** 14\
**Last updated:** [April 11, 2022, 2:36pm UTC](https://discourse.julialang.org/t/alternatives-to-base-hash/79154 "2022-04-11T14:36:16Z")

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Are there packages that implement alternatives to Base.hash? I am interested in a somewhat different set of tradeoffs than what Base.hash provides: Should be able to hash any object (like Base.hash) Should have a negli…

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## [Calling Fortran subroutine from Julia passing array arguments](https://discourse.julialang.org/t/calling-fortran-subroutine-from-julia-passing-array-arguments/79340)

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**Author:** [@Marie](https://discourse.julialang.org/u/Marie)\
**Replies:** 5\
**Last updated:** [April 11, 2022, 2:13pm UTC](https://discourse.julialang.org/t/calling-fortran-subroutine-from-julia-passing-array-arguments/79340 "2022-04-11T14:13:25Z")

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Fortran subroutine looks like this: subroutine MatMult(a, b, m, n, k, answer) !DEC$ ATTRIBUTES DLLEXPORT :: MatMult !DEC$ ATTRIBUTES ALIAS: 'MatMult' :: MatMult !DEC$ ATTRIBUTES REFERENCE :: a …

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## [\`@variables\` and \`@parameters\` macros not working on arrays](https://discourse.julialang.org/t/variables-and-parameters-macros-not-working-on-arrays/79252)

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**Author:** [@markjholmes](https://discourse.julialang.org/u/markjholmes)\
**Replies:** 14\
**Last updated:** [April 11, 2022, 1:51pm UTC](https://discourse.julialang.org/t/variables-and-parameters-macros-not-working-on-arrays/79252 "2022-04-11T13:51:30Z")

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I have Julia installed on two different computers and the code executes differently on each one despite having the same versions of VSCode, Julia, and installed packages (everything is the most recent release version). T…

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## [Frustrating distributed task exception](https://discourse.julialang.org/t/frustrating-distributed-task-exception/68579)

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**Author:** [@yiming\_zhang](https://discourse.julialang.org/u/yiming_zhang)\
**Replies:** 7\
**Last updated:** [April 11, 2022, 1:42pm UTC](https://discourse.julialang.org/t/frustrating-distributed-task-exception/68579 "2022-04-11T13:42:13Z")

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Progress: 0%|▏ | ETA: 1:48:49Worker 41 terminated. Progress: 99%|████████████████████████████████████████▍| ETA: 0:00:01ERROR: LoadError: TaskFailedException Stacktrace: \[1\] w…

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## [Access DataFrames index](https://discourse.julialang.org/t/access-dataframes-index/79342)

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**Author:** [@this\_josh](https://discourse.julialang.org/u/this_josh)\
**Replies:** 1\
**Last updated:** [April 11, 2022, 12:22pm UTC](https://discourse.julialang.org/t/access-dataframes-index/79342 "2022-04-11T12:22:18Z")

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I’m sure this a trivial task but I cannot find the answer. I have a Julia DataFrame and I’d like the index as an array, in pandas I can do: \>\>\> import pandas as pd \>\>\> df = pd.DataFrame(\[1,2,3,4,5\]) \>\>\> df.index RangeIn…

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## [Request for review basic introductory pages on ML, Perceptron, Neural Networks](https://discourse.julialang.org/t/request-for-review-basic-introductory-pages-on-ml-perceptron-neural-networks/79341)

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**Author:** [@sylvaticus](https://discourse.julialang.org/u/sylvaticus)\
**Replies:** 0\
**Last updated:** [April 11, 2022, 11:53am UTC](https://discourse.julialang.org/t/request-for-review-basic-introductory-pages-on-ml-perceptron-neural-networks/79341 "2022-04-11T11:53:24Z")

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Hello, I have a couple of pages dealing with: General ML concepts and perceptron algorithm Neural network architectures These two small “pages” are targeted to non-cs / non-math students that know nothing of ML, with …

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## [How to specifiy 1.8-beta in CI.yaml](https://discourse.julialang.org/t/how-to-specifiy-1-8-beta-in-ci-yaml/79339)

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**Author:** [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Replies:** 2\
**Last updated:** [April 11, 2022, 11:43am UTC](https://discourse.julialang.org/t/how-to-specifiy-1-8-beta-in-ci-yaml/79339 "2022-04-11T11:43:00Z")

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I have the following in my CI.yaml file: matrix: version: - '1.6' - '1' - 'nightly' os: - ubuntu-latest But how can I specify testing on 1.8-beta instead of ‘nightly’?

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## [Iterators.flatmap optimization attempt](https://discourse.julialang.org/t/iterators-flatmap-optimization-attempt/79265)

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**Author:** [@xor0110](https://discourse.julialang.org/u/xor0110)\
**Replies:** 2\
**Last updated:** [April 11, 2022, 11:38am UTC](https://discourse.julialang.org/t/iterators-flatmap-optimization-attempt/79265 "2022-04-11T11:38:47Z")

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Following the nice conversation at #44792 I’m trying to investigate the question of whether flatmap functions might offer performance benefits. I suspect that in general flatten(x) cannot do better than a flatmap(identit…

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## [File extension for jupyter to discriminate between Python and Julia notebooks](https://discourse.julialang.org/t/file-extension-for-jupyter-to-discriminate-between-python-and-julia-notebooks/79115)

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**Author:** [@martinmestre](https://discourse.julialang.org/u/martinmestre)\
**Replies:** 8\
**Last updated:** [April 11, 2022, 11:10am UTC](https://discourse.julialang.org/t/file-extension-for-jupyter-to-discriminate-between-python-and-julia-notebooks/79115 "2022-04-11T11:10:59Z")

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Hello all, sometimes I use Julia and Python notebooks in VS Code. I would like to have another extension like “notebook.ijl” to discriminate respect to the Python notebooks (.ipynb), and also respect to common “.jl” file…

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## [Unexpected : isstructtype( Vector{Float64}) =\> true](https://discourse.julialang.org/t/unexpected-isstructtype-vector-float64-true/79283)

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**Author:** [@reumle](https://discourse.julialang.org/u/reumle)\
**Replies:** 13\
**Last updated:** [April 11, 2022, 11:06am UTC](https://discourse.julialang.org/t/unexpected-isstructtype-vector-float64-true/79283 "2022-04-11T11:06:23Z")

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According to the help, it should not happen… isstructtype(T) -\> Bool Determine whether type T was declared as a struct type (i.e. using the struct or mutable struct keyword). Is this a bug? Or am I misunderstanding so…

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## [Error with user-defined rates in Catalyst.jl](https://discourse.julialang.org/t/error-with-user-defined-rates-in-catalyst-jl/79229)

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**Author:** [@SiddhantDeshmukh](https://discourse.julialang.org/u/SiddhantDeshmukh)\
**Replies:** 4\
**Last updated:** [April 11, 2022, 10:19am UTC](https://discourse.julialang.org/t/error-with-user-defined-rates-in-catalyst-jl/79229 "2022-04-11T10:19:06Z")

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Hello everyone, I’m fairly new to Julia and would like to use Catalyst.jl to solve ODE systems across a large simulation grid. To that end, I’ve been trying out some test problems, and have encountered an issue with dec…

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## [How to solve failure to load CSV in Julia?](https://discourse.julialang.org/t/how-to-solve-failure-to-load-csv-in-julia/79335)

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**Author:** [@Luigi\_Marongiu](https://discourse.julialang.org/u/Luigi_Marongiu)\
**Replies:** 1\
**Last updated:** [April 11, 2022, 9:28am UTC](https://discourse.julialang.org/t/how-to-solve-failure-to-load-csv-in-julia/79335 "2022-04-11T09:28:25Z")

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Hello, I wanted to load CSV in the environment but I got this error: julia\> using CSV \[ Info: Precompiling CSV \[336ed68f-0bac-5ca0-87d4-7b16caf5d00b\] ERROR: LoadError: MethodError: no method matching Parsers.Options(::M…

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