# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1558

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

**Page:** 1559

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## [QML.jl release pending](https://discourse.julialang.org/t/qml-jl-release-pending/43758)

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**Author:** [@barche](https://discourse.julialang.org/u/barche)\
**Replies:** 17\
**Last updated:** [December 1, 2020, 10:52pm UTC](https://discourse.julialang.org/t/qml-jl-release-pending/43758 "2020-12-01T22:52:02Z")

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Hi everyone, It has been in the works for a long time, but QML.jl is finally ready for release, with the registration PR pending. In the mean time, you can test it using: add https://github.com/barche/QML.jl.git See t…

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## [How to rewrite Julia programming language from scratch?](https://discourse.julialang.org/t/how-to-rewrite-julia-programming-language-from-scratch/50897)

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**Author:** [@vedasulo](https://discourse.julialang.org/u/vedasulo)\
**Replies:** 15\
**Last updated:** [December 1, 2020, 10:37pm UTC](https://discourse.julialang.org/t/how-to-rewrite-julia-programming-language-from-scratch/50897 "2020-12-01T22:37:19Z")

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I want to change julia and add python like features to it. Make syntax look like Python but inside it is Julia compiler-based. Is it possible? How can I do this? Thank you :slight\_smile:

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## [Features most wanted in Julia](https://discourse.julialang.org/t/features-most-wanted-in-julia/50821)

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**Author:** [@jakobnissen](https://discourse.julialang.org/u/jakobnissen)\
**Replies:** 10\
**Last updated:** [December 1, 2020, 10:32pm UTC](https://discourse.julialang.org/t/features-most-wanted-in-julia/50821 "2020-12-01T22:32:45Z")

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We had an excellent discussion on Slack the other day where many people gave input to what they considered the “biggest things missing in Julia”. I thought it would be a shame if all the feedback just disappeared into th…

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## [Approaching first usable release of TextUserInterfaces.jl](https://discourse.julialang.org/t/approaching-first-usable-release-of-textuserinterfaces-jl/50971)

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**Author:** [@Ronis\_BR](https://discourse.julialang.org/u/Ronis_BR)\
**Replies:** 8\
**Last updated:** [December 1, 2020, 9:47pm UTC](https://discourse.julialang.org/t/approaching-first-usable-release-of-textuserinterfaces-jl/50971 "2020-12-01T21:47:16Z")

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Hi! After a long time developing TextUserInterfaces.jl, I finally could implement the last feature I wanted before starting the code cleaning and documentation process: Dialogs! If everything goes right, we are just ab…

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## [Most accurate way to compute x/sqrt(y) in Julia?](https://discourse.julialang.org/t/most-accurate-way-to-compute-x-sqrt-y-in-julia/51061)

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**Author:** [@marcus](https://discourse.julialang.org/u/marcus)\
**Replies:** 11\
**Last updated:** [December 1, 2020, 8:39pm UTC](https://discourse.julialang.org/t/most-accurate-way-to-compute-x-sqrt-y-in-julia/51061 "2020-12-01T20:39:28Z")

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As part of a numerical algorithm, I want to compute x/\\sqrt{y} for real numbers x and y. In general is it preferable to compute x/sqrt(y) or x\*sqrt(1/y) or x\*1/sqrt(y)? As a slightly less trivial example, is there an op…

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## [NLsolve false convergence](https://discourse.julialang.org/t/nlsolve-false-convergence/50922)

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**Author:** [@Maria95](https://discourse.julialang.org/u/Maria95)\
**Replies:** 6\
**Last updated:** [December 1, 2020, 5:16pm UTC](https://discourse.julialang.org/t/nlsolve-false-convergence/50922 "2020-12-01T17:16:15Z")

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Hi, I am a new user of Julia and this may sound like a basic question. I am trying to use NLsolve to find a solution to an equation of the form: f(x)= ∑a0+a1 \*1/(1+x)^(b\[1\])+a2 \*1/(1+x)^(b\[2\])+ a3 \*1/(1+x)^(b\[3\])+⋯ By …

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## [\[ANN\] HybridArrays.jl: arrays with both static and dynamic axes](https://discourse.julialang.org/t/ann-hybridarrays-jl-arrays-with-both-static-and-dynamic-axes/31038)

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**Author:** [@mateuszbaran](https://discourse.julialang.org/u/mateuszbaran)\
**Replies:** 14\
**Last updated:** [December 1, 2020, 4:53pm UTC](https://discourse.julialang.org/t/ann-hybridarrays-jl-arrays-with-both-static-and-dynamic-axes/31038 "2020-12-01T16:53:58Z")

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I’ve made HybridArrays.jl, an extension to StaticArrays.jl that makes it easier to work with arrays that have both statically and dynamically sized axes. It should be as fast (or almost as fast) as Arrays of SArrays wher…

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## [Help testing PrettyTables v0.10.0](https://discourse.julialang.org/t/help-testing-prettytables-v0-10-0/49609)

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**Author:** [@Ronis\_BR](https://discourse.julialang.org/u/Ronis_BR)\
**Replies:** 14\
**Last updated:** [December 1, 2020, 4:12pm UTC](https://discourse.julialang.org/t/help-testing-prettytables-v0-10-0/49609 "2020-12-01T16:12:48Z")

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Hi guys! I just tagged v0.10.0 of PrettyTables.jl. It should be available really soon. This is a huge release, with a lot of new features, and, unfortunately, a lot of breaking changes (sorry!). The point of this releas…

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## [Streaming CSV Reader from IO Type which does not load all Data into memory](https://discourse.julialang.org/t/streaming-csv-reader-from-io-type-which-does-not-load-all-data-into-memory/51050)

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**Author:** [@altre](https://discourse.julialang.org/u/altre)\
**Replies:** 2\
**Last updated:** [December 1, 2020, 3:56pm UTC](https://discourse.julialang.org/t/streaming-csv-reader-from-io-type-which-does-not-load-all-data-into-memory/51050 "2020-12-01T15:56:08Z")

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I am looking for a way to read from a stream of CSV Rows, i.e. from an IO (or LibuvStream) type without reading the whole table into memory. This currently works e.g. with CSV.jl’s CSV.Rows when reading a file since it …

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## [Can Julia efficiently make use of 20+ cores for transforming hundreds of millions of rows for machine learning?](https://discourse.julialang.org/t/can-julia-efficiently-make-use-of-20-cores-for-transforming-hundreds-of-millions-of-rows-for-machine-learning/50968)

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**Author:** [@Kevin\_Shen](https://discourse.julialang.org/u/Kevin_Shen)\
**Replies:** 27\
**Last updated:** [December 1, 2020, 3:15pm UTC](https://discourse.julialang.org/t/can-julia-efficiently-make-use-of-20-cores-for-transforming-hundreds-of-millions-of-rows-for-machine-learning/50968 "2020-12-01T15:15:30Z")

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I’ve seen similar questions posted but I wanted to ask my question to see if I can get more precise answers. I train machine learning models on datasets with hundreds of millions of rows (10^8). On this order of magnitu…

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## [Creating a registry](https://discourse.julialang.org/t/creating-a-registry/12094)

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**Author:** [@adamslc](https://discourse.julialang.org/u/adamslc)\
**Replies:** 29\
**Last updated:** [December 1, 2020, 3:13pm UTC](https://discourse.julialang.org/t/creating-a-registry/12094 "2020-12-01T15:13:12Z")

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I just spend quite a lot of time trying to create a custom registry for the new package manager, so I figured I would document my process so that it goes smoother for the next person. Our goal is to create a registry Te…

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## [Jaccard index from a dataframe/array](https://discourse.julialang.org/t/jaccard-index-from-a-dataframe-array/51044)

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**Author:** [@HelgavonLichtenstein](https://discourse.julialang.org/u/HelgavonLichtenstein)\
**Replies:** 3\
**Last updated:** [December 1, 2020, 3:04pm UTC](https://discourse.julialang.org/t/jaccard-index-from-a-dataframe-array/51044 "2020-12-01T15:04:31Z")

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I am trying to calculate the Jaccard Index of an array/DataFrame using the package Distance.jl, and am having difficulty. using Distances, DataFrames zxcv = \[0.0 0.0 1.0;0.0 0.0 1.0;0.0 0.0 0.0\] dist = evaluate(jaccard…

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## [Get eigenvectors of non-normal, defective matrices in julia](https://discourse.julialang.org/t/get-eigenvectors-of-non-normal-defective-matrices-in-julia/50871)

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**Author:** [@volkerkarle](https://discourse.julialang.org/u/volkerkarle)\
**Replies:** 7\
**Last updated:** [December 1, 2020, 2:11pm UTC](https://discourse.julialang.org/t/get-eigenvectors-of-non-normal-defective-matrices-in-julia/50871 "2020-12-01T14:11:07Z")

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Dear community, Given a non-normal defective matrix, how can I get all eigenvectors of this matrix? An obvious way would be to use the jordan normal form. I wonder if somebody already calculated the jordan normal form …

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## [How to find inflection point of curve?](https://discourse.julialang.org/t/how-to-find-inflection-point-of-curve/50892)

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**Author:** [@Luigi\_Marongiu](https://discourse.julialang.org/u/Luigi_Marongiu)\
**Replies:** 20\
**Last updated:** [November 30, 2020, 7:56am UTC](https://discourse.julialang.org/t/how-to-find-inflection-point-of-curve/50892 "2020-11-30T07:56:38Z")

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Hello, I have the function y = ϑ - ((1/ω) \* log(x/ε)) - 1/μ Is there a simple way in Julia to find the flection point of the function? if I set these paramaters: mu = 0.72 # maximum growth rate resistant (…

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## [Why do I get this error "UndefVarError: cov not defined"](https://discourse.julialang.org/t/why-do-i-get-this-error-undefvarerror-cov-not-defined/50239)

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**Author:** [@RaquelSantos](https://discourse.julialang.org/u/RaquelSantos)\
**Replies:** 16\
**Last updated:** [November 30, 2020, 6:42pm UTC](https://discourse.julialang.org/t/why-do-i-get-this-error-undefvarerror-cov-not-defined/50239 "2020-11-30T18:42:28Z")

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Could someone help me solve the error: UndefVarError: cov not defined of the test code taken from the site JuMPeR - Robust Optimization with JuMP — JuMPeR -- Julia for Mathematical Programming 0.0 documentation Did thi…

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## [Travis CI changes pricing plans](https://discourse.julialang.org/t/travis-ci-changes-pricing-plans/49528)

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**Author:** [@ranocha](https://discourse.julialang.org/u/ranocha)\
**Replies:** 14\
**Last updated:** [December 1, 2020, 11:42am UTC](https://discourse.julialang.org/t/travis-ci-changes-pricing-plans/49528 "2020-12-01T11:42:30Z")

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Quoting from Blog – Travis-CI We love our OSS teams who choose to build using TravisCI and we fully want to support that community. However, recently we have encountered significant abuse of the intention of this offer…

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## [How to replace/set/change value in array/dataframe if value is less/greater than?](https://discourse.julialang.org/t/how-to-replace-set-change-value-in-array-dataframe-if-value-is-less-greater-than/51039)

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**Author:** [@HelgavonLichtenstein](https://discourse.julialang.org/u/HelgavonLichtenstein)\
**Replies:** 3\
**Last updated:** [December 1, 2020, 10:53am UTC](https://discourse.julialang.org/t/how-to-replace-set-change-value-in-array-dataframe-if-value-is-less-greater-than/51039 "2020-12-01T10:53:51Z")

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Hello, I had some code that used to work but it must have been for a previous version of Julia. I can’t find what I am looking for in the DataFrame docs Getting Started · DataFrames.jl I want to replace values in an arr…

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## [Update "min" and "max" of Ranged Slider via "relayoutData" of Figure not working](https://discourse.julialang.org/t/update-min-and-max-of-ranged-slider-via-relayoutdata-of-figure-not-working/51037)

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**Author:** [@lambcount](https://discourse.julialang.org/u/lambcount)\
**Replies:** 0\
**Last updated:** [December 1, 2020, 10:12am UTC](https://discourse.julialang.org/t/update-min-and-max-of-ranged-slider-via-relayoutdata-of-figure-not-working/51037 "2020-12-01T10:12:06Z")

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Hi , i am quite new to Julia and especially Dash. So maybe there is an easy fix to my problems. I want to plot a heatmap and then add via callback vlines to the heatmap. That is working quite well. In another callback…

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## [Created package is not defiened with using PkgTemplates](https://discourse.julialang.org/t/created-package-is-not-defiened-with-using-pkgtemplates/50934)

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**Author:** [@Amirrezz94](https://discourse.julialang.org/u/Amirrezz94)\
**Replies:** 6\
**Last updated:** [December 1, 2020, 10:03am UTC](https://discourse.julialang.org/t/created-package-is-not-defiened-with-using-pkgtemplates/50934 "2020-12-01T10:03:47Z")

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Hi, I tried to create a simple package using PkgTemplates package. I used this template on invenia website to create my package: t = Template(; user="Amirrezz94", dir="C:\\\\Users\\\\Amirr\\\\.julia\\\\dev", author…

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## [When should I write loops or vectorised calls?](https://discourse.julialang.org/t/when-should-i-write-loops-or-vectorised-calls/50812)

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**Author:** [@lrnv](https://discourse.julialang.org/u/lrnv)\
**Replies:** 17\
**Last updated:** [December 1, 2020, 6:36am UTC](https://discourse.julialang.org/t/when-should-i-write-loops-or-vectorised-calls/50812 "2020-12-01T06:36:23Z")

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Hi, Comming from numpy and R, I am customed to the fact that vectorised expressions are faster than loops. I understood this is not the case in julia, where vectorised expression are usually expended out to loops by the…

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## [Not sure how to generate ForwardDiff function](https://discourse.julialang.org/t/not-sure-how-to-generate-forwarddiff-function/51030)

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**Author:** [@brett\_knoss](https://discourse.julialang.org/u/brett_knoss)\
**Replies:** 1\
**Last updated:** [December 1, 2020, 6:01am UTC](https://discourse.julialang.org/t/not-sure-how-to-generate-forwarddiff-function/51030 "2020-12-01T06:01:21Z")

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I try to run this, but it says there is a format problem, I think with line 3 (fp(x)) using ForwardDiff f(x)=x^6-2 fp(x) = x-\>ForwardDiff.derivative(f, x) x=1.5 x=x-(f(x)/fp(x))

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## [Evaluation in calling scope?](https://discourse.julialang.org/t/evaluation-in-calling-scope/34897)

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**Author:** [@tomtom](https://discourse.julialang.org/u/tomtom)\
**Replies:** 22\
**Last updated:** [December 1, 2020, 4:51am UTC](https://discourse.julialang.org/t/evaluation-in-calling-scope/34897 "2020-12-01T04:51:27Z")

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from docs, eval() “Evaluate an expression in the global scope of the containing module” as follows: julia\> ex = :(x + 1) :(x + 1) julia\> f() = (x = 10; println(x + 1, " ", eval(ex) ); g() ) f (generic function with 1 m…

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## [BoundsError: attempt to access Float64 using ModelingToolkit.jl and AutoOptimize.jl to optimize a DifferentialEquations.jl model](https://discourse.julialang.org/t/boundserror-attempt-to-access-float64-using-modelingtoolkit-jl-and-autooptimize-jl-to-optimize-a-differentialequations-jl-model/51000)

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**Author:** [@claudio20497](https://discourse.julialang.org/u/claudio20497)\
**Replies:** 1\
**Last updated:** [December 1, 2020, 4:35am UTC](https://discourse.julialang.org/t/boundserror-attempt-to-access-float64-using-modelingtoolkit-jl-and-autooptimize-jl-to-optimize-a-differentialequations-jl-model/51000 "2020-12-01T04:35:19Z")

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Hello, I’m trying to optimize the code and finding the best solve algorithm for an epidemiological model. Anyway, I get an error that due to my inexperience I cannot solve. So below is a simplified verison of the model…

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## [Multi-threaded matrix exponential slower than the single threaded version](https://discourse.julialang.org/t/multi-threaded-matrix-exponential-slower-than-the-single-threaded-version/51009)

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**Author:** [@JakobA](https://discourse.julialang.org/u/JakobA)\
**Replies:** 7\
**Last updated:** [December 1, 2020, 3:49am UTC](https://discourse.julialang.org/t/multi-threaded-matrix-exponential-slower-than-the-single-threaded-version/51009 "2020-12-01T03:49:29Z")

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I am trying to perform many matrix exponentials in parallel. However, the multi-threaded code running on 40 cores (2x Skylake 6148) takes about twice as long as the single-threaded code. Here is a minimal working example…

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## [Make own personal static website in julia?](https://discourse.julialang.org/t/make-own-personal-static-website-in-julia/51024)

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**Author:** [@Ravinder\_Ram](https://discourse.julialang.org/u/Ravinder_Ram)\
**Replies:** 1\
**Last updated:** [December 1, 2020, 3:41am UTC](https://discourse.julialang.org/t/make-own-personal-static-website-in-julia/51024 "2020-12-01T03:41:42Z")

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Like in rmarkdown in R and you can crreate own static website … is there any feature / package in julia for that

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## [Proper way to make an empty sizehinted Dict](https://discourse.julialang.org/t/proper-way-to-make-an-empty-sizehinted-dict/50962)

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**Author:** [@malacroi](https://discourse.julialang.org/u/malacroi)\
**Replies:** 1\
**Last updated:** [December 1, 2020, 2:03am UTC](https://discourse.julialang.org/t/proper-way-to-make-an-empty-sizehinted-dict/50962 "2020-12-01T02:03:13Z")

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I have an application where it seems appropriate to have a Dict effectively containing a large number of lightly wrapped Dict containers. Say something like, d = Dict{Int64,Dict{Int64,Int128}}(), where the indices of d …

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## [Packages for Optimization](https://discourse.julialang.org/t/packages-for-optimization/50926)

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**Author:** [@brett\_knoss](https://discourse.julialang.org/u/brett_knoss)\
**Replies:** 22\
**Last updated:** [December 1, 2020, 1:10am UTC](https://discourse.julialang.org/t/packages-for-optimization/50926 "2020-12-01T01:10:51Z")

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What are some good packages for optimization. I’ve been using Roots.jl and ModelingToolkit.jl to do symbolic derivatives and find the zero roots, but I’m considering packages that actually look for minimums and maximums…

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## [Debugger.@enter shows lowered code when types are provided](https://discourse.julialang.org/t/debugger-enter-shows-lowered-code-when-types-are-provided/51010)

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**Author:** [@asyrov](https://discourse.julialang.org/u/asyrov)\
**Replies:** 1\
**Last updated:** [November 30, 2020, 11:36pm UTC](https://discourse.julialang.org/t/debugger-enter-shows-lowered-code-when-types-are-provided/51010 "2020-11-30T23:36:04Z")

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I’m using Debugger module to debug functions, which I type in REPL. Now, if I do not specify types of parameters and return value I can see source code with @enter as I expect. But if I specify types of parameters and re…

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## [Resources to get started with differential equations](https://discourse.julialang.org/t/resources-to-get-started-with-differential-equations/50747)

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**Author:** [@danielw2904](https://discourse.julialang.org/u/danielw2904)\
**Replies:** 8\
**Last updated:** [November 30, 2020, 10:20pm UTC](https://discourse.julialang.org/t/resources-to-get-started-with-differential-equations/50747 "2020-11-30T22:20:49Z")

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I’m putting this in off-topic since my question is more general. I want to learn more about the sci-ml type packages eventually but feel like I lack some fundamental knowledge on \*DEs and would therefore ask for recommen…

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## [Solving ODE based on experimental data (DifferentialEquations.jl)](https://discourse.julialang.org/t/solving-ode-based-on-experimental-data-differentialequations-jl/51002)

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**Author:** [@maajdl](https://discourse.julialang.org/u/maajdl)\
**Replies:** 4\
**Last updated:** [November 30, 2020, 9:09pm UTC](https://discourse.julialang.org/t/solving-ode-based-on-experimental-data-differentialequations-jl/51002 "2020-11-30T21:09:51Z")

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Hello, I am solving a simple ODE system with 5 state variables. It is essentially made of 5 coupled RC sytems with a few (current) excitations. These excitations are 6000 experimental data measured every 10 minutes. …

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