# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1476

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

**Page:** 1477

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## [Finding array indices without creating an array using vectors?](https://discourse.julialang.org/t/finding-array-indices-without-creating-an-array-using-vectors/56125)

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**Author:** [@taeukseo](https://discourse.julialang.org/u/taeukseo)\
**Replies:** 15\
**Last updated:** [February 27, 2021, 10:12pm UTC](https://discourse.julialang.org/t/finding-array-indices-without-creating-an-array-using-vectors/56125 "2021-02-27T22:12:56Z")

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I apologize for the poor phrasing of the question - it sounds like an oxymoron! :neutral\_face: I have been struggling to write a function F which, given: vectors of sizes N1, N2, N3… etc a number 1\<= i \<= N1 \* N2 \* N…

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## [Converting user-supplied strings/text to EBCDIC hexadecimal characters](https://discourse.julialang.org/t/converting-user-supplied-strings-text-to-ebcdic-hexadecimal-characters/56120)

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**Author:** [@tg\_15](https://discourse.julialang.org/u/tg_15)\
**Replies:** 3\
**Last updated:** [February 27, 2021, 8:39pm UTC](https://discourse.julialang.org/t/converting-user-supplied-strings-text-to-ebcdic-hexadecimal-characters/56120 "2021-02-27T20:39:35Z")

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I am currently trying to explore how to convert user-supplied plaintext to hexadecimal characters in ASCII and EBCDIC. The website I’m developing requires the user to supply a string (256 chars min), select ASCII or EBCD…

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## [Nested map](https://discourse.julialang.org/t/nested-map/55889)

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**Author:** [@eschoute](https://discourse.julialang.org/u/eschoute)\
**Replies:** 12\
**Last updated:** [February 27, 2021, 7:01pm UTC](https://discourse.julialang.org/t/nested-map/55889 "2021-02-27T19:01:52Z")

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I’d like to apply a function to each element of a nested array. To illustrate julia\> arr = \[\[1,2,3\],\[4,5,6\]\] 2-element Array{Array{Int64,1},1}: \[1, 2, 3\] \[4, 5, 6\] julia\> map(arr) do ls map(ls) do x …

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## [\[ANN\] HITRAN.jl](https://discourse.julialang.org/t/ann-hitran-jl/56150)

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**Author:** [@Hawkes](https://discourse.julialang.org/u/Hawkes)\
**Replies:** 0\
**Last updated:** [February 27, 2021, 6:32pm UTC](https://discourse.julialang.org/t/ann-hitran-jl/56150 "2021-02-27T18:32:25Z")

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Dear all, I’m happy to announce the release of HITRAN.jl, a package meant for calculating high-resolution molecular absorption spectra based on the HITRAN database. The package takes a similar approach as the official …

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## [\[ANN\] Metatheory.jl](https://discourse.julialang.org/t/ann-metatheory-jl/55451)

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**Author:** [@0x0f0f0f](https://discourse.julialang.org/u/0x0f0f0f)\
**Replies:** 11\
**Last updated:** [February 27, 2021, 6:05pm UTC](https://discourse.julialang.org/t/ann-metatheory-jl/55451 "2021-02-27T18:05:18Z")

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Hi everybody! I’m happy to announce that the first version of Metatheory.jl is out! You can find the code here GitHub - JuliaSymbolics/Metatheory.jl: General purpose algebraic metaprogramming and symbolic computation li…

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## [Symbolic rewriting, expanding and collecting](https://discourse.julialang.org/t/symbolic-rewriting-expanding-and-collecting/55503)

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**Author:** [@Janis\_Erdmanis](https://discourse.julialang.org/u/Janis_Erdmanis)\
**Replies:** 11\
**Last updated:** [February 27, 2021, 5:47pm UTC](https://discourse.julialang.org/t/symbolic-rewriting-expanding-and-collecting/55503 "2021-02-27T17:47:42Z")

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Hi! I need to revise a lot of mundane analytical calculations which I guess could be automated. In its essence, I have three sets of symbols: operators E, X, C, S \\in \\rm{Op}, sigma matrices \\eta\_x, \\eta\_y, \\eta\_z \\in S…

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## [Issues with Starting Julia: Juno/Atom/Julia](https://discourse.julialang.org/t/issues-with-starting-julia-juno-atom-julia/56062)

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**Author:** [@atparedes](https://discourse.julialang.org/u/atparedes)\
**Replies:** 2\
**Last updated:** [February 27, 2021, 5:40pm UTC](https://discourse.julialang.org/t/issues-with-starting-julia-juno-atom-julia/56062 "2021-02-27T17:40:27Z")

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I recently install Julia 1.5.3 and I am having issues getting it to start using Juno/Atom: julia\> Julia has exited. Press Enter to start a new session. Starting Julia… I saw several discussions on this issues, but w…

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## [Optimize function with complex square root](https://discourse.julialang.org/t/optimize-function-with-complex-square-root/56058)

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**Author:** [@mleprovost](https://discourse.julialang.org/u/mleprovost)\
**Replies:** 12\
**Last updated:** [February 27, 2021, 5:24pm UTC](https://discourse.julialang.org/t/optimize-function-with-complex-square-root/56058 "2021-02-27T17:24:32Z")

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Hello, I am writing a routine to store a matrix that contains the values of f(x, z) = \\frac{1}{\\sqrt{1-x^2}} \\times \\text{real}\\left(\\frac{\\sqrt{z-1}\\sqrt{z+1}}{z-x}\\right) for \\sim 1000 real values x \\in \[-1, 1\] and \\…

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## [\[Solved\] CSV.write(), file opens correctly in excel, but wrong layout in text](https://discourse.julialang.org/t/solved-csv-write-file-opens-correctly-in-excel-but-wrong-layout-in-text/56130)

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**Author:** [@AIRoebl](https://discourse.julialang.org/u/AIRoebl)\
**Replies:** 2\
**Last updated:** [February 27, 2021, 3:43pm UTC](https://discourse.julialang.org/t/solved-csv-write-file-opens-correctly-in-excel-but-wrong-layout-in-text/56130 "2021-02-27T15:43:55Z")

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Hi, I hope someone can help me here, I’ve been banging away at this for a day now. I’m using CSV.write() to write a dataframe to a CSV file (.txt). The output opens perfectly in excel, but the layout isn’t right in the t…

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## [Error when building documentation with github actions](https://discourse.julialang.org/t/error-when-building-documentation-with-github-actions/56139)

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**Author:** [@Azzaare](https://discourse.julialang.org/u/Azzaare)\
**Replies:** 2\
**Last updated:** [February 27, 2021, 2:31pm UTC](https://discourse.julialang.org/t/error-when-building-documentation-with-github-actions/56139 "2021-02-27T14:31:37Z")

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I’ve just generated a new package and put it on GitHub COPInstances.jl I get the following error while building the documentation. Which is odd as I have the same setup for other packages (beside not being registered ye…

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## [Is there a method to check if a vector is "sortable"?](https://discourse.julialang.org/t/is-there-a-method-to-check-if-a-vector-is-sortable/56127)

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**Author:** [@sylvaticus](https://discourse.julialang.org/u/sylvaticus)\
**Replies:** 6\
**Last updated:** [February 27, 2021, 12:23pm UTC](https://discourse.julialang.org/t/is-there-a-method-to-check-if-a-vector-is-sortable/56127 "2021-02-27T12:23:35Z")

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In a Decision Tree algorithm I implement an optimisation where I first sort the vector of data once and then I pick up the various items with searchsorted. All fine for integers, floats, even strings… but If the vector …

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## [Multithread image processing with Cairo.jl / Luxor.jl possible?](https://discourse.julialang.org/t/multithread-image-processing-with-cairo-jl-luxor-jl-possible/55920)

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**Author:** [@Fred](https://discourse.julialang.org/u/Fred)\
**Replies:** 5\
**Last updated:** [February 27, 2021, 12:00pm UTC](https://discourse.julialang.org/t/multithread-image-processing-with-cairo-jl-luxor-jl-possible/55920 "2021-02-27T12:00:35Z")

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Hi, This is a toy program that draw circles on the Julia logo. It woks sequentially but when I try to do parallel image processing I have this error with Julia 1.5.3 up to date. julia: cairo-surface.c :2092 : \_cairo\_su…

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## [C: get variables from embedded julia](https://discourse.julialang.org/t/c-get-variables-from-embedded-julia/56134)

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**Author:** [@achjaj](https://discourse.julialang.org/u/achjaj)\
**Replies:** 0\
**Last updated:** [February 27, 2021, 10:39am UTC](https://discourse.julialang.org/t/c-get-variables-from-embedded-julia/56134 "2021-02-27T10:39:53Z")

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Hello, is there any way how I can get a list of all variables (and their values) in the global scope from Julia embedded in a C/C++ application? Documentation is not very helpful in this case.

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## [ERROR: LoadError: importing WaterLily into Main conflicts with an existing identifier](https://discourse.julialang.org/t/error-loaderror-importing-waterlily-into-main-conflicts-with-an-existing-identifier/56086)

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**Author:** [@meck](https://discourse.julialang.org/u/meck)\
**Replies:** 3\
**Last updated:** [February 27, 2021, 10:20am UTC](https://discourse.julialang.org/t/error-loaderror-importing-waterlily-into-main-conflicts-with-an-existing-identifier/56086 "2021-02-27T10:20:05Z")

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Hello, this is my first Julia Repo I am trying to run, so maybe it is a beginners Julia problem. However I want to ask this here as well, if I may. When trying to run a Script from folder examples I get the mentione…

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## [Does anyone else find the behavior of \`Dict(::NamedTuple)\` a little funky:\`\`\`juli](https://discourse.julialang.org/t/does-anyone-else-find-the-behavior-of-dict-namedtuple-a-little-funky-juli/56050)

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**Author:** [@BridgeBot](https://discourse.julialang.org/u/BridgeBot)\
**Replies:** 1\
**Last updated:** [February 27, 2021, 10:08am UTC](https://discourse.julialang.org/t/does-anyone-else-find-the-behavior-of-dict-namedtuple-a-little-funky-juli/56050 "2021-02-27T10:08:17Z")

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does anyone else find the behavior of Dict(::NamedTuple) a little funky: julia&gt; kw = (default\_u0 = \[0., 0., 0.\], default\_p=\[0., 0., 0.\]) (default\_u0 = \[0.0, 0.0, 0.0\], default\_p = \[0.0, 0.0, 0.0\]) julia&gt; kwd = …

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## [How to adjust the X-axis order of boxplot with StatsPlots.jl](https://discourse.julialang.org/t/how-to-adjust-the-x-axis-order-of-boxplot-with-statsplots-jl/56065)

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**Author:** [@Shuhua](https://discourse.julialang.org/u/Shuhua)\
**Replies:** 9\
**Last updated:** [February 27, 2021, 7:37am UTC](https://discourse.julialang.org/t/how-to-adjust-the-x-axis-order-of-boxplot-with-statsplots-jl/56065 "2021-02-27T07:37:24Z")

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using Plots, StatsPlots, DataFrames df = DataFrame( id=repeat(\[3, 17, 21\], inner=10), value=randn(30) ) @df df boxplot(string.(:id), :value, fillalpha=0.75, linewidth=1) The result is I want the box to be 3…

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## [Converting between AxisArray like packages?](https://discourse.julialang.org/t/converting-between-axisarray-like-packages/52510)

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**Author:** [@jw3126](https://discourse.julialang.org/u/jw3126)\
**Replies:** 18\
**Last updated:** [February 27, 2021, 3:31am UTC](https://discourse.julialang.org/t/converting-between-axisarray-like-packages/52510 "2021-02-27T03:31:06Z")

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In Julia there are many AxisArrays.jl like packages, that implement variants of an array with metadata attached to its axes. This means every once in a while, one has to convert arrays between these. After doing lots of…

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## [Behavior of ImmutableDict](https://discourse.julialang.org/t/behavior-of-immutabledict/56107)

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**Author:** [@anon60034542](https://discourse.julialang.org/u/anon60034542)\
**Replies:** 4\
**Last updated:** [February 26, 2021, 11:59pm UTC](https://discourse.julialang.org/t/behavior-of-immutabledict/56107 "2021-02-26T23:59:29Z")

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Can anyone explain why ImmutableDict works the way it does? I can’t specify the type when declaring it: # Produces MethodError. weapons = ImmutableDict{String,Int32}("Light-Rifle" =\> 100, "Plasma-Pistol" =\> 50) I can’…

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## [World age error using urldownload to read a zip file](https://discourse.julialang.org/t/world-age-error-using-urldownload-to-read-a-zip-file/56111)

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**Author:** [@brianguenter](https://discourse.julialang.org/u/brianguenter)\
**Replies:** 4\
**Last updated:** [February 26, 2021, 11:12pm UTC](https://discourse.julialang.org/t/world-age-error-using-urldownload-to-read-a-zip-file/56111 "2021-02-26T23:12:23Z")

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I am getting a world age error when using urldownload (from package UrlDownload). Does anybody know why this might happen? Here’s the error message: ‘’’ Info: tmp ERROR: LoadError: MethodError: no method matching eof…

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## [Julia from the perspective of a pythonista](https://discourse.julialang.org/t/julia-from-the-perspective-of-a-pythonista/55956)

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**Author:** [@dariush-bahrami](https://discourse.julialang.org/u/dariush-bahrami)\
**Replies:** 121\
**Last updated:** [February 26, 2021, 10:41pm UTC](https://discourse.julialang.org/t/julia-from-the-perspective-of-a-pythonista/55956 "2021-02-26T22:41:21Z")

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Julia from the perspective of a pythonista Intruduction I will start this post with a brief description of myself. I have been writing code in the Python programming language for about 3 years. My main interest is in art…

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## [Passing an Arrow Table from Python to Julia](https://discourse.julialang.org/t/passing-an-arrow-table-from-python-to-julia/56104)

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**Author:** [@Satvik](https://discourse.julialang.org/u/Satvik)\
**Replies:** 2\
**Last updated:** [February 26, 2021, 9:30pm UTC](https://discourse.julialang.org/t/passing-an-arrow-table-from-python-to-julia/56104 "2021-02-26T21:30:02Z")

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Hi, I have a Python job that calls Julia for some computation on my datasets. Right now, passing data back and forth between Julia and Python is a bottleneck – my current process is to save the Pandas DataFrame as a fea…

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## [Transforming a type](https://discourse.julialang.org/t/transforming-a-type/56118)

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**Author:** [@jzr](https://discourse.julialang.org/u/jzr)\
**Replies:** 2\
**Last updated:** [February 26, 2021, 9:25pm UTC](https://discourse.julialang.org/t/transforming-a-type/56118 "2021-02-26T21:25:49Z")

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I have a Person type and I want to make another type that’s similar but allows missing values in the fields. Is this possible? struct Person name::String age::Int end struct IncompletePerson name::Union{Str…

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## [JSON string to composite type](https://discourse.julialang.org/t/json-string-to-composite-type/56112)

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**Author:** [@vladflore](https://discourse.julialang.org/u/vladflore)\
**Replies:** 2\
**Last updated:** [February 26, 2021, 8:03pm UTC](https://discourse.julialang.org/t/json-string-to-composite-type/56112 "2021-02-26T20:03:43Z")

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Hi, I was trying to consume a rest API, specifically to make a GET request and transform the response into a custom composite type. Unfortunately, I am missing something, because I am getting errors I cannot quite under…

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## [Import struct from other module as a parameter](https://discourse.julialang.org/t/import-struct-from-other-module-as-a-parameter/56080)

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**Author:** [@akhil\_teja](https://discourse.julialang.org/u/akhil_teja)\
**Replies:** 7\
**Last updated:** [February 26, 2021, 7:18pm UTC](https://discourse.julialang.org/t/import-struct-from-other-module-as-a-parameter/56080 "2021-02-26T19:18:12Z")

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I’ve following dir structure: -\> Calc (root dir) -\> src -\> Calc.jl -\> Controls.jl -\> Models.jl Below are the content of the files: Calc.jl: module Calc include("Models…

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## [Plans to port SLICOT Toeplitz solvers to Julia?](https://discourse.julialang.org/t/plans-to-port-slicot-toeplitz-solvers-to-julia/55996)

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**Author:** [@BambOoxX](https://discourse.julialang.org/u/BambOoxX)\
**Replies:** 5\
**Last updated:** [February 26, 2021, 6:35pm UTC](https://discourse.julialang.org/t/plans-to-port-slicot-toeplitz-solvers-to-julia/55996 "2021-02-26T18:35:53Z")

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I saw that the MatrixEquations.jl package was released to reproduce some solvers related to Riccati and Lyapunov equations, linked with the SLICOT library. Are there any plans to link the Toeplitz specialized solvers fr…

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## [Julia Distributed, AllReduce, and Distributed Training](https://discourse.julialang.org/t/julia-distributed-allreduce-and-distributed-training/55808)

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**Author:** [@asaxton](https://discourse.julialang.org/u/asaxton)\
**Replies:** 3\
**Last updated:** [February 26, 2021, 6:31pm UTC](https://discourse.julialang.org/t/julia-distributed-allreduce-and-distributed-training/55808 "2021-02-26T18:31:03Z")

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I’m working with Distributed Julia on multiple hosts and want to write some code that does distributed training with a machine learning model and distributed data. I don’t want to use MPI. I have the ClusterManager worki…

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## [Optimizing a Loss Function that takes arguments in addition to parameters](https://discourse.julialang.org/t/optimizing-a-loss-function-that-takes-arguments-in-addition-to-parameters/56040)

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**Author:** [@donkeysaddle](https://discourse.julialang.org/u/donkeysaddle)\
**Replies:** 2\
**Last updated:** [February 26, 2021, 5:48pm UTC](https://discourse.julialang.org/t/optimizing-a-loss-function-that-takes-arguments-in-addition-to-parameters/56040 "2021-02-26T17:48:03Z")

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If I have a loss function that I want to use for optimizing a set of parameters, can that function take additional arguments as well (e.g., arrays that might vary in size, and boolean statements)? If the answer is “yes”…

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## [How to use for loop or collection in SemialgebraicSets?](https://discourse.julialang.org/t/how-to-use-for-loop-or-collection-in-semialgebraicsets/56106)

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**Author:** [@aliceee](https://discourse.julialang.org/u/aliceee)\
**Replies:** 0\
**Last updated:** [February 26, 2021, 6:11pm UTC](https://discourse.julialang.org/t/how-to-use-for-loop-or-collection-in-semialgebraicsets/56106 "2021-02-26T18:11:31Z")

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I’m trying to specify a semialgebraic set in a SumofSquare model: @set vec(A\*vec\_x1)\[1\]\>=0 && vec(A\*vec\_x1)\[2\] && vec(A\*vec\_x1)\[3\]\>=0&&vec(A\*vec\_x1)\[4\] where A is a two-dimensional polyvar, vec\_x1 is a constant vector.…

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## [Hi everyone, hope this is the right channel. New to Julia, long-time R user. I am](https://discourse.julialang.org/t/hi-everyone-hope-this-is-the-right-channel-new-to-julia-long-time-r-user-i-am/56087)

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**Author:** [@BridgeBot](https://discourse.julialang.org/u/BridgeBot)\
**Replies:** 3\
**Last updated:** [February 26, 2021, 6:07pm UTC](https://discourse.julialang.org/t/hi-everyone-hope-this-is-the-right-channel-new-to-julia-long-time-r-user-i-am/56087 "2021-02-26T18:07:43Z")

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Hi everyone, hope this is the right channel. New to Julia, long-time R user. I am looking for the equivalent of R’s approxfun in Julia and its use in ODE systems (as in here: https://tpetzoldt.github.io/deSolve-forcing/d…

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## [Reduce order of differential equations to first-order](https://discourse.julialang.org/t/reduce-order-of-differential-equations-to-first-order/56090)

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**Author:** [@fms-1988](https://discourse.julialang.org/u/fms-1988)\
**Replies:** 2\
**Last updated:** [February 26, 2021, 5:48pm UTC](https://discourse.julialang.org/t/reduce-order-of-differential-equations-to-first-order/56090 "2021-02-26T17:48:56Z")

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I am working with differential equations. Some of my procedures require me to reduce the order of the ODE. Matlab has an efficient algorithm to do this (here). My doubt is: is there an algorithm similar to this for Ju…

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