# Latest

**URL:** https://discourse.julialang.org/latest.md?page=619

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

**Page:** 620

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## [GR interactivity in Pluto](https://discourse.julialang.org/t/gr-interactivity-in-pluto/48906)

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**Author:** [@Oto\_Brzobohaty](https://discourse.julialang.org/u/Oto_Brzobohaty)\
**Replies:** 14\
**Last updated:** [August 16, 2023, 6:04am UTC](https://discourse.julialang.org/t/gr-interactivity-in-pluto/48906 "2023-08-16T06:04:12Z")

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I have found this post I have downloaded the example notebook pluto\_ex.jl But I got this error UndefVarError: init\_pluto not defined in this cell begin ENV\["GRDISPLAY"\] = "pluto" using GR GR.js.init\_pluto()…

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## [Why is the ticks fontfamily not changing?](https://discourse.julialang.org/t/why-is-the-ticks-fontfamily-not-changing/102814)

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**Author:** [@SYSYS33](https://discourse.julialang.org/u/SYSYS33)\
**Replies:** 4\
**Last updated:** [August 16, 2023, 5:42am UTC](https://discourse.julialang.org/t/why-is-the-ticks-fontfamily-not-changing/102814 "2023-08-16T05:42:50Z")

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I am using Julia 1.9.2, Plots v1.38.17, PyPlot v2.11.1. When I plot, the font of the tick labels doesn’t change. Not working “fontfamily” and “tickfontfamily”. Is this a bug in the new version of Julia, or is there a …

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## [Computer Algebra "factor" function](https://discourse.julialang.org/t/computer-algebra-factor-function/102837)

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**Author:** [@maxasauruswall](https://discourse.julialang.org/u/maxasauruswall)\
**Replies:** 2\
**Last updated:** [August 16, 2023, 2:45am UTC](https://discourse.julialang.org/t/computer-algebra-factor-function/102837 "2023-08-16T02:45:07Z")

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Hi All, I’m reading “Computer Algebra Concepts and Techniques” by Lamagna (I’m new to CAS systems, and fairly new to Julia as well). I was curious to see if I could follow along with some of the examples in Julia, rathe…

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## [NLopt optimizer just return the initial value](https://discourse.julialang.org/t/nlopt-optimizer-just-return-the-initial-value/102820)

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**Author:** [@MKY](https://discourse.julialang.org/u/MKY)\
**Replies:** 3\
**Last updated:** [August 16, 2023, 2:25am UTC](https://discourse.julialang.org/t/nlopt-optimizer-just-return-the-initial-value/102820 "2023-08-16T02:25:19Z")

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opt = Opt(:LD\_SLSQP,4) opt.lower\_bounds = \[0,0,0,0\] opt.ftol\_abs = 1e-20 opt.min\_objective = risk\_budget\_objective equality\_constraint!(opt,weights -\> total\_weight\_constraint(x)) (optf,optx,ret) = optimize(opt,\[0.25,0.25…

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## [Ternary Operator \`?:\` on a DataFrame :)](https://discourse.julialang.org/t/ternary-operator-on-a-dataframe/102798)

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**Author:** [@eweiss](https://discourse.julialang.org/u/eweiss)\
**Replies:** 11\
**Last updated:** [August 16, 2023, 12:43am UTC](https://discourse.julialang.org/t/ternary-operator-on-a-dataframe/102798 "2023-08-16T00:43:38Z")

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I’m trying to use the ternary operator and get an error message: ERROR: ArgumentError: It is only allowed to pass a vector as a column of a DataFrame." Here’s my code: using DataFrames # Sample DataFrame with two c…

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## [Assigning a user-defined function to RobotDynamics.dynamics()](https://discourse.julialang.org/t/assigning-a-user-defined-function-to-robotdynamics-dynamics/102842)

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**Author:** [@shawn\_T](https://discourse.julialang.org/u/shawn_T)\
**Replies:** 3\
**Last updated:** [August 15, 2023, 10:27pm UTC](https://discourse.julialang.org/t/assigning-a-user-defined-function-to-robotdynamics-dynamics/102842 "2023-08-15T22:27:24Z")

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Hi, I am using the RobotDynamics Julia interface to define an optimal control problem, specifically, I would like to dynamically create a function that matches the style of function that RobotDynamics.dynamics() support…

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## [SymataSyntax.jl: Mathematica syntax for Symata](https://discourse.julialang.org/t/symatasyntax-jl-mathematica-syntax-for-symata/759)

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**Author:** [@jlapeyre](https://discourse.julialang.org/u/jlapeyre)\
**Replies:** 1\
**Last updated:** [August 15, 2023, 10:21pm UTC](https://discourse.julialang.org/t/symatasyntax-jl-mathematica-syntax-for-symata/759 "2023-08-15T22:21:26Z")

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SymataSyntax.jl allows you to use Symtata with Mathematica syntax. At the moment, Mma syntax can be entered in a terminal REPL or read from a file. You need to checkout the latest master branch of Symata.jl, not the …

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## [Julia Match.jl match error with Date - pattern expects 3 fields](https://discourse.julialang.org/t/julia-match-jl-match-error-with-date-pattern-expects-3-fields/102580)

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**Author:** [@bryaan](https://discourse.julialang.org/u/bryaan)\
**Replies:** 3\
**Last updated:** [August 15, 2023, 8:55pm UTC](https://discourse.julialang.org/t/julia-match-jl-match-error-with-date-pattern-expects-3-fields/102580 "2023-08-15T20:55:45Z")

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Just updated my project deps and am getting this really strange error with a Match.jl @match statement. ERROR: The type \`Dates.Date\` has 1 fields but the pattern expects 3 fields. @match date begin Date(2023, 4…

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## [Bizarre d(variable) syntax encountered when reading model written in .mdl file](https://discourse.julialang.org/t/bizarre-d-variable-syntax-encountered-when-reading-model-written-in-mdl-file/102645)

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**Author:** [@ajcost](https://discourse.julialang.org/u/ajcost)\
**Replies:** 5\
**Last updated:** [August 15, 2023, 8:45pm UTC](https://discourse.julialang.org/t/bizarre-d-variable-syntax-encountered-when-reading-model-written-in-mdl-file/102645 "2023-08-15T20:45:16Z")

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I was wondering if anyone had familiarity with something called MoDeL language. It seems to be some AML type optimization language. I found bizarre syntax in which constraints are written with d(variable). Meaning “chang…

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## [Understanding an Enzyme Warning Message](https://discourse.julialang.org/t/understanding-an-enzyme-warning-message/102825)

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**Author:** [@nina](https://discourse.julialang.org/u/nina)\
**Replies:** 1\
**Last updated:** [August 15, 2023, 7:38pm UTC](https://discourse.julialang.org/t/understanding-an-enzyme-warning-message/102825 "2023-08-15T19:38:18Z")

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When training a UDE with many parameters (\>100) I get an Enzyme warning if I do not select the AD algorithm a-priori. This warning appears not once, but several times during the optimization process. While I can obviousl…

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## [Plots weird problem plotting a piecewise function at discontinuity points](https://discourse.julialang.org/t/plots-weird-problem-plotting-a-piecewise-function-at-discontinuity-points/102811)

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**Author:** [@Albert\_Zevelev](https://discourse.julialang.org/u/Albert_Zevelev)\
**Replies:** 13\
**Last updated:** [August 15, 2023, 7:34pm UTC](https://discourse.julialang.org/t/plots-weird-problem-plotting-a-piecewise-function-at-discontinuity-points/102811 "2023-08-15T19:34:05Z")

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using Plots; g\_k =0.0:0.01:10.0; A1=1.0; A2=2.0; α=0.33; κ2 =3.0; κ̂2 = κ2 / (1.0 - ((A1/A2)^(1/α))); #3.41842 function f3p(k) if (k \< κ̂2) return α\*A1\*(k^(α - 1.0)) elseif (k \> κ̂2) return α\*A2\*(…

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## [Populate a symmetric sparse matrix](https://discourse.julialang.org/t/populate-a-symmetric-sparse-matrix/102830)

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**Author:** [@mleprovost](https://discourse.julialang.org/u/mleprovost)\
**Replies:** 10\
**Last updated:** [August 15, 2023, 7:16pm UTC](https://discourse.julialang.org/t/populate-a-symmetric-sparse-matrix/102830 "2023-08-15T19:16:42Z")

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Hello, I would like to populate a sparse matrix A with a function f:\\mathbb{N}\\times \\mathbb{N} \\to \\mathbb{R}, (i\_1, i\_2) \\mapsto f(i\_1, i\_2) which is symmetric, i.e. f(i\_1, i\_2) = f(i\_2, i\_1). We want to fill A such…

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## [Q: Vector of vectors of variable lengths](https://discourse.julialang.org/t/q-vector-of-vectors-of-variable-lengths/102817)

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**Author:** [@Audrius-St](https://discourse.julialang.org/u/Audrius-St)\
**Replies:** 6\
**Last updated:** [August 15, 2023, 6:37pm UTC](https://discourse.julialang.org/t/q-vector-of-vectors-of-variable-lengths/102817 "2023-08-15T18:37:47Z")

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Hello, What is the recommended/best Julia method to create a vector of vectors of variable lengths? Current method MWE: # test\_vector\_of\_vectors.jl begin vec\_of\_vecs = \[Float64\[\] for \_ in 1:3\] for i = 1:3 …

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## [A categorical speaking indictment - making scientific computing more relevant to the general public](https://discourse.julialang.org/t/a-categorical-speaking-indictment-making-scientific-computing-more-relevant-to-the-general-public/102702)

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**Author:** [@g2g](https://discourse.julialang.org/u/g2g)\
**Replies:** 1\
**Last updated:** [August 15, 2023, 6:05pm UTC](https://discourse.julialang.org/t/a-categorical-speaking-indictment-making-scientific-computing-more-relevant-to-the-general-public/102702 "2023-08-15T18:05:40Z")

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Perhaps a way to increase Julia’s relevance to the general public is by increasing scientific computing’s relevance to the general public. For example, the following diagram generated by Julia and GLMakie is a summary of…

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## [\[ANN\] DomainColoring(Toy).jl – Smooth Complex Plotting](https://discourse.julialang.org/t/ann-domaincoloring-toy-jl-smooth-complex-plotting/102080)

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**Author:** [@eprovst](https://discourse.julialang.org/u/eprovst)\
**Replies:** 3\
**Last updated:** [August 15, 2023, 5:12pm UTC](https://discourse.julialang.org/t/ann-domaincoloring-toy-jl-smooth-complex-plotting/102080 "2023-08-15T17:12:59Z")

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In complex analysis, one can gain much intuition by looking at visual representations of phase, magnitude, etc. Phase plots, domain colorings, and other kinds of plots are hence useful tools, such as demonstrated in the …

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## [Using symbols from parent module without naming it](https://discourse.julialang.org/t/using-symbols-from-parent-module-without-naming-it/101833)

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**Author:** [@Tamas\_Papp](https://discourse.julialang.org/u/Tamas_Papp)\
**Replies:** 21\
**Last updated:** [August 15, 2023, 11:36am UTC](https://discourse.julialang.org/t/using-symbols-from-parent-module-without-naming-it/101833 "2023-08-15T11:36:19Z")

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Is it possible to import/using a symbol for a parent module without naming it? Eg module Foo const c = 1 module Bar using ..Foo:c # like this, but without referring to Foo f() = c end end

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## [Package testing; setup and teardown](https://discourse.julialang.org/t/package-testing-setup-and-teardown/102834)

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**Author:** [@frylock](https://discourse.julialang.org/u/frylock)\
**Replies:** 1\
**Last updated:** [August 15, 2023, 3:52pm UTC](https://discourse.julialang.org/t/package-testing-setup-and-teardown/102834 "2023-08-15T15:52:06Z")

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I have a package that wraps a vendor library. There is one main object that is exposed (a simulator) and the changeable parts are all available by performing functions on the main object, made to look C++ ish with getpro…

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## [Stability of a system of delay differential equations](https://discourse.julialang.org/t/stability-of-a-system-of-delay-differential-equations/102829)

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**Author:** [@Ananya\_Hazarika](https://discourse.julialang.org/u/Ananya_Hazarika)\
**Replies:** 1\
**Last updated:** [August 15, 2023, 3:48pm UTC](https://discourse.julialang.org/t/stability-of-a-system-of-delay-differential-equations/102829 "2023-08-15T15:48:12Z")

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hello, How to check the stability of a system of delay differential equations? I only only need to see if the system is stable in what range of parameters /at a certain parameter value set. Please help:).

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## [Why is Julia faster than C++ for quicksort?](https://discourse.julialang.org/t/why-is-julia-faster-than-c-for-quicksort/102669)

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**Author:** [@mariusd](https://discourse.julialang.org/u/mariusd)\
**Replies:** 15\
**Last updated:** [August 15, 2023, 3:24pm UTC](https://discourse.julialang.org/t/why-is-julia-faster-than-c-for-quicksort/102669 "2023-08-15T15:24:58Z")

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See the following pieces of code for quicksort, adapted from GitHub - JuliaLang/Microbenchmarks: Microbenchmarks comparing the Julia Programming language with other languages. As you can see in the benchmark output, juli…

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## [Makie @recipe need understanding](https://discourse.julialang.org/t/makie-recipe-need-understanding/102563)

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**Author:** [@Allan\_Baker](https://discourse.julialang.org/u/Allan_Baker)\
**Replies:** 10\
**Last updated:** [August 15, 2023, 3:14pm UTC](https://discourse.julialang.org/t/makie-recipe-need-understanding/102563 "2023-08-15T15:14:09Z")

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I’m having no luck finding a working example of how to define a makie @recipe for a custom type, or in this case custom types. I have a home grown quaternion and a 3D vector type which match better how legacy simulation…

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## [How to sample from MvNormal without allocating?](https://discourse.julialang.org/t/how-to-sample-from-mvnormal-without-allocating/96646)

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**Author:** [@markmbaum](https://discourse.julialang.org/u/markmbaum)\
**Replies:** 5\
**Last updated:** [August 15, 2023, 2:29pm UTC](https://discourse.julialang.org/t/how-to-sample-from-mvnormal-without-allocating/96646 "2023-08-15T14:29:28Z")

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Even using the in-place method rand! to sample from a MvNormal distribution seems to allocate some memory and be orders of magnitude slower than the univariate case. I only have a two dimensional case, so I was hoping to…

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## [@turbo Segfault with empty rows in SparseMatrix](https://discourse.julialang.org/t/turbo-segfault-with-empty-rows-in-sparsematrix/102821)

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**Author:** [@f.ij](https://discourse.julialang.org/u/f.ij)\
**Replies:** 1\
**Last updated:** [August 15, 2023, 1:17pm UTC](https://discourse.julialang.org/t/turbo-segfault-with-empty-rows-in-sparsematrix/102821 "2023-08-15T13:17:03Z")

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I’m trying to use the @turbo macro from LoopVectorization iterating over values from a sparse array. The way I’m doing it is the following: I have a variable state::Vector{Float32} and a square sparse matrix holding Flo…

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## [Scalar indexing is disallowed](https://discourse.julialang.org/t/scalar-indexing-is-disallowed/102808)

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**Author:** [@A\_M](https://discourse.julialang.org/u/A_M)\
**Replies:** 4\
**Last updated:** [August 15, 2023, 12:50pm UTC](https://discourse.julialang.org/t/scalar-indexing-is-disallowed/102808 "2023-08-15T12:50:58Z")

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Can you tell me why I am getting it? ERROR: LoadError: Scalar indexing is disallowed. Invocation of getindex resulted in scalar indexing of a GPU array. This is typically caused by calling an iterating implementation of…

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## [Slurping in not final position](https://discourse.julialang.org/t/slurping-in-not-final-position/102784)

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**Author:** [@rocco\_sprmnt21](https://discourse.julialang.org/u/rocco_sprmnt21)\
**Replies:** 11\
**Last updated:** [August 15, 2023, 12:45pm UTC](https://discourse.julialang.org/t/slurping-in-not-final-position/102784 "2023-08-15T12:45:10Z")

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I was running the roames notebook exercises, in an attempt to fix this: Create a more generic reduce2 function that works recursively over a tuple For the operations + and \*, being associative, simulate the operatio…

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## [Help speeding up submatrix extraction from SparseCSC](https://discourse.julialang.org/t/help-speeding-up-submatrix-extraction-from-sparsecsc/102131)

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**Author:** [@foobar\_lv2](https://discourse.julialang.org/u/foobar_lv2)\
**Replies:** 1\
**Last updated:** [August 15, 2023, 11:05am UTC](https://discourse.julialang.org/t/help-speeding-up-submatrix-extraction-from-sparsecsc/102131 "2023-08-15T11:05:14Z")

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Hello again, I’d like to ask for help optimizing the extraction of a dense submatrix from a SparseCSC matrix. In other words, submatrix\_reference(spmat, rows, cols) = Matrix(spmat\[rows, cols\]) where spmat is a sparse …

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## [Recommended TOTP application to enable 2FA on Github?](https://discourse.julialang.org/t/recommended-totp-application-to-enable-2fa-on-github/102802)

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**Author:** [@ffevotte](https://discourse.julialang.org/u/ffevotte)\
**Replies:** 7\
**Last updated:** [August 15, 2023, 10:28am UTC](https://discourse.julialang.org/t/recommended-totp-application-to-enable-2fa-on-github/102802 "2023-08-15T10:28:08Z")

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I just received a reminder that I still haven’t activated 2FA for my GitHub account. I understand I have to choose a TOTP application (the GitHub message mentions 1Password, Authy and Microsoft Authenticator), but I’m no…

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## [AMPL to Julia](https://discourse.julialang.org/t/ampl-to-julia/102800)

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**Author:** [@Julianewbie](https://discourse.julialang.org/u/Julianewbie)\
**Replies:** 3\
**Last updated:** [August 15, 2023, 10:30am UTC](https://discourse.julialang.org/t/ampl-to-julia/102800 "2023-08-15T10:30:30Z")

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Hello, I am trying to convert an AMPL file to Julia and I dont know how to get started I have the following expressions that I need help with so I can use them as a reference to get started, the second one should be a f…

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## [Model building problem](https://discourse.julialang.org/t/model-building-problem/102783)

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**Author:** [@jack\_lee](https://discourse.julialang.org/u/jack_lee)\
**Replies:** 13\
**Last updated:** [August 15, 2023, 7:27am UTC](https://discourse.julialang.org/t/model-building-problem/102783 "2023-08-15T07:27:32Z")

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The target of a survey is set as business people and college students, requirements: The total number is 600,and student is not less than 250; the way of survey includes questionnaire and phone, the number is questionn…

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## [Compute intensive function rewrite](https://discourse.julialang.org/t/compute-intensive-function-rewrite/102809)

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**Author:** [@BioinfoBuggaBoo](https://discourse.julialang.org/u/BioinfoBuggaBoo)\
**Replies:** 2\
**Last updated:** [August 15, 2023, 5:08am UTC](https://discourse.julialang.org/t/compute-intensive-function-rewrite/102809 "2023-08-15T05:08:50Z")

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I have been using a package in R that really only has one main function which does a lot behind the scenes of which a portion is prohibitively slow to the point where the timescales involved are far too long to ever achi…

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## [Converting CartesianIndices to a vector of vectors](https://discourse.julialang.org/t/converting-cartesianindices-to-a-vector-of-vectors/102794)

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**Author:** [@Gus\_Hart](https://discourse.julialang.org/u/Gus_Hart)\
**Replies:** 12\
**Last updated:** [August 15, 2023, 1:21am UTC](https://discourse.julialang.org/t/converting-cartesianindices-to-a-vector-of-vectors/102794 "2023-08-15T01:21:02Z")

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I’m using CartesianIndices to generate lists resembling base-k numbers. I want the convert the output into a “flat” vector of vectors, irrespective of the number of “digits” passed to CartesianIndices. The lists will gen…

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