# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1242

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

**Page:** 1243

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## [\[ANN/RFC\] Multi-column expressions with implicit broadcasting for DataFrameMacros.jl](https://discourse.julialang.org/t/ann-rfc-multi-column-expressions-with-implicit-broadcasting-for-dataframemacros-jl/69543)

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**Author:** [@jules](https://discourse.julialang.org/u/jules)\
**Replies:** 0\
**Last updated:** [October 11, 2021, 8:29am UTC](https://discourse.julialang.org/t/ann-rfc-multi-column-expressions-with-implicit-broadcasting-for-dataframemacros-jl/69543 "2021-10-11T08:29:56Z")

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Hi all, I want to share a cool upcoming feature of DataFrameMacros with you (currently in this PR multiple columns by jkrumbiegel · Pull Request #15 · jkrumbiegel/DataFrameMacros.jl · GitHub) and get some thoughts on two…

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## [How do we exec a julia program for competitive programming?](https://discourse.julialang.org/t/how-do-we-exec-a-julia-program-for-competitive-programming/25470)

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**Author:** [@p1scescom](https://discourse.julialang.org/u/p1scescom)\
**Replies:** 2\
**Last updated:** [October 11, 2021, 8:38am UTC](https://discourse.julialang.org/t/how-do-we-exec-a-julia-program-for-competitive-programming/25470 "2021-10-11T08:38:57Z")

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Hey everyone. I want your idea to exec a julia program quickly and usefuly for competitive prgramming. You may not know competitive programming. It is A programming competition generally involves the host presenting…

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## [Printing non linear expression in model](https://discourse.julialang.org/t/printing-non-linear-expression-in-model/69505)

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**Author:** [@manoj.centura](https://discourse.julialang.org/u/manoj.centura)\
**Replies:** 5\
**Last updated:** [October 11, 2021, 7:10am UTC](https://discourse.julialang.org/t/printing-non-linear-expression-in-model/69505 "2021-10-11T07:10:59Z")

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Hi All, is there a way to print non linear expression model=Model() @variable(model,x) exp1 =@NLexpression(model,x\*x) @NLconstraint(model,exp1\<=10) println("exp1",exp1) output exp1"Reference to nonlinear expression …

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## [Unable to load Queryverse](https://discourse.julialang.org/t/unable-to-load-queryverse/69539)

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**Author:** [@PAHH](https://discourse.julialang.org/u/PAHH)\
**Replies:** 0\
**Last updated:** [October 11, 2021, 4:59am UTC](https://discourse.julialang.org/t/unable-to-load-queryverse/69539 "2021-10-11T04:59:46Z")

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Hi all, I’m using Julia 1.6.3 (VS Code 1.61.0) and am unable to use the Queryverse package. I first tried to load it onto my current environment (which also contains StatsKit among other things), but then I tried to load…

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## [Is Julia's way of OOP superior to C++/Python? Why Julia doesn't use class-based OOP?](https://discourse.julialang.org/t/is-julias-way-of-oop-superior-to-c-python-why-julia-doesnt-use-class-based-oop/52058)

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**Author:** [@vedasulo](https://discourse.julialang.org/u/vedasulo)\
**Replies:** 146\
**Last updated:** [October 11, 2021, 6:16am UTC](https://discourse.julialang.org/t/is-julias-way-of-oop-superior-to-c-python-why-julia-doesnt-use-class-based-oop/52058 "2021-10-11T06:16:44Z")

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I am thinking How can it applied in large projects or software development projects, if there is no oop. I heard struct and things. But some answer told It is not oop. What are advantage and disadvantage of using oop i…

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## [True interactive development](https://discourse.julialang.org/t/true-interactive-development/67318)

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**Author:** [@tk3369](https://discourse.julialang.org/u/tk3369)\
**Replies:** 36\
**Last updated:** [October 11, 2021, 6:12am UTC](https://discourse.julialang.org/t/true-interactive-development/67318 "2021-10-11T06:12:25Z")

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I stumbled upon this blog while casually scanning hacker news. So I thought Julia REPL + Revise is top notch until it described “true interactive development” as follows: True interactive development is also about pr…

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## [Prototyping and code development](https://discourse.julialang.org/t/prototyping-and-code-development/69405)

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**Author:** [@kumarbalachandran](https://discourse.julialang.org/u/kumarbalachandran)\
**Replies:** 3\
**Last updated:** [October 11, 2021, 5:25am UTC](https://discourse.julialang.org/t/prototyping-and-code-development/69405 "2021-10-11T05:25:15Z")

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I have been comparing prototyping of code within Pluto and within VS Code and I have a way of working that seems to be okay. But, I’d like to point out some failings of the tools available: Debug within VS Code is sa…

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## [Large memory allocation when a loop is threaded, none when run single-threaded](https://discourse.julialang.org/t/large-memory-allocation-when-a-loop-is-threaded-none-when-run-single-threaded/69535)

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**Author:** [@Chris\_Green](https://discourse.julialang.org/u/Chris_Green)\
**Replies:** 12\
**Last updated:** [October 11, 2021, 4:31am UTC](https://discourse.julialang.org/t/large-memory-allocation-when-a-loop-is-threaded-none-when-run-single-threaded/69535 "2021-10-11T04:31:42Z")

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I have a simple volume rendering loop coded in julia. It uses fixed size 3d vector classes based around the StaticArrays package, derive from FieldVector: struct Vector3D{T} \<: FieldVector{3, T} x::T y::T z:…

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## [Appropriate channel to report "nightly" CI failures](https://discourse.julialang.org/t/appropriate-channel-to-report-nightly-ci-failures/69536)

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**Author:** [@goerz](https://discourse.julialang.org/u/goerz)\
**Replies:** 1\
**Last updated:** [October 11, 2021, 3:43am UTC](https://discourse.julialang.org/t/appropriate-channel-to-report-nightly-ci-failures/69536 "2021-10-11T03:43:22Z")

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My packages have a Github CI (set up by PkgTemplates) that tests against “nightly” Julia. Today, I started seeing some segfault failures, e.g. https://github.com/JuliaQuantumControl/Krotov.jl/runs/3854753074?check\_suite\_…

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## ["all posts" or follow keyword/package](https://discourse.julialang.org/t/all-posts-or-follow-keyword-package/69528)

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**Author:** [@lmiq](https://discourse.julialang.org/u/lmiq)\
**Replies:** 5\
**Last updated:** [October 11, 2021, 12:30am UTC](https://discourse.julialang.org/t/all-posts-or-follow-keyword-package/69528 "2021-10-11T00:30:20Z")

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I found out today that someone asking something specific about a package of mine reminded without answer for a month. I look at the forum almost every day, so missing that specific post was particularly unreasonable. T…

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## [The macrocall @\_\_FILE\_\_ does not return the directory of the file, but rather the REPL output number](https://discourse.julialang.org/t/the-macrocall-file-does-not-return-the-directory-of-the-file-but-rather-the-repl-output-number/55585)

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**Author:** [@bionicinnovations1](https://discourse.julialang.org/u/bionicinnovations1)\
**Replies:** 8\
**Last updated:** [October 10, 2021, 11:43pm UTC](https://discourse.julialang.org/t/the-macrocall-file-does-not-return-the-directory-of-the-file-but-rather-the-repl-output-number/55585 "2021-10-10T23:43:06Z")

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I have been using to following to change my working directory to the location of my .jl scripts in Atom as follows without problems: cd(dirname(@\_\_FILE\_\_)) When I run a script with this in vs code, I get an error and i…

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## [Load and reformatting CSV file](https://discourse.julialang.org/t/load-and-reformatting-csv-file/69518)

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**Author:** [@rami](https://discourse.julialang.org/u/rami)\
**Replies:** 6\
**Last updated:** [October 10, 2021, 11:10pm UTC](https://discourse.julialang.org/t/load-and-reformatting-csv-file/69518 "2021-10-10T23:10:12Z")

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Hello, I am trying to load a CSV file from a Github rep, reformat, and store it as DataFrame obj. Here is what I tried: using CSV, HTTP, DataFrames url = "https://raw.githubusercontent.com/RamiKrispin/coronavirus/maste…

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## [New type definition: Galois field in Julia 1.x](https://discourse.julialang.org/t/new-type-definition-galois-field-in-julia-1-x/17123)

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**Author:** [@KZiemian](https://discourse.julialang.org/u/KZiemian)\
**Replies:** 8\
**Last updated:** [October 10, 2021, 10:42pm UTC](https://discourse.julialang.org/t/new-type-definition-galois-field-in-julia-1-x/17123 "2021-10-10T22:42:38Z")

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I try to work very nice examples of defining new type, \\textrm{GF}( p ) = \\mathbb{Z} / p where p is prime number. It looks like there syntax is not working in 1.x version. Can it be recover with few changes here and ther…

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## [Dictionaries can't find keys](https://discourse.julialang.org/t/dictionaries-cant-find-keys/69488)

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**Author:** [@brett\_knoss](https://discourse.julialang.org/u/brett_knoss)\
**Replies:** 34\
**Last updated:** [October 10, 2021, 8:56pm UTC](https://discourse.julialang.org/t/dictionaries-cant-find-keys/69488 "2021-10-10T20:56:40Z")

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I have this dictionary starting\_balance=starting\_balance=Dict( # Starting Balance consists of a dictionary, containing debit and credit dictionaries, containing accounts as empty dictionaries. #accounts are organized…

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## [Adding two Array{Union{Missing,Float64}} returns Array{Float64}, is this by design?](https://discourse.julialang.org/t/adding-two-array-union-missing-float64-returns-array-float64-is-this-by-design/69472)

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**Author:** [@viraltux](https://discourse.julialang.org/u/viraltux)\
**Replies:** 32\
**Last updated:** [October 10, 2021, 8:44pm UTC](https://discourse.julialang.org/t/adding-two-array-union-missing-float64-returns-array-float64-is-this-by-design/69472 "2021-10-10T20:44:49Z")

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y = Array{Union{Missing,Float64}}(undef,100); y\[:\] = rand(100) ϵ = Array{Union{Missing,Float64}}(undef,100); ϵ\[:\] = rand(100) julia\> eltype(y.+ϵ) Float64 I am not sure but I imagine the idea behind doing this is return…

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## [Get all object field values as tuple](https://discourse.julialang.org/t/get-all-object-field-values-as-tuple/69517)

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**Author:** [@andrey2185](https://discourse.julialang.org/u/andrey2185)\
**Replies:** 2\
**Last updated:** [October 10, 2021, 7:30pm UTC](https://discourse.julialang.org/t/get-all-object-field-values-as-tuple/69517 "2021-10-10T19:30:57Z")

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Hellow! how can i get all object field values as tuple better as this: object\_field\_values = (getproperty.(repeat(\[object\],fieldcount(T)), fieldnames(T))...,)

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## [Cholesky simple example](https://discourse.julialang.org/t/cholesky-simple-example/69480)

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**Author:** [@Jakub\_Mitura](https://discourse.julialang.org/u/Jakub_Mitura)\
**Replies:** 11\
**Last updated:** [October 10, 2021, 6:19pm UTC](https://discourse.julialang.org/t/cholesky-simple-example/69480 "2021-10-10T18:19:20Z")

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Hello I try to implement from basis (I need it for GPU kernel (just small 3 by 3 matrix one of multiple things that a kernel do - no point in using cublas …) so -can not using Linear algebra package for a moment , als…

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## [General registry delays, and a workaround](https://discourse.julialang.org/t/general-registry-delays-and-a-workaround/67537)

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**Author:** [@dilumaluthge](https://discourse.julialang.org/u/dilumaluthge)\
**Replies:** 4\
**Last updated:** [October 10, 2021, 6:13pm UTC](https://discourse.julialang.org/t/general-registry-delays-and-a-workaround/67537 "2021-10-10T18:13:17Z")

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From time to time, you may notice that a new package or new version is not available for installation on your local computer, even though the corresponding pull request has been merged in the General registry. This is c…

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## [Override default object display length in REPL/env?](https://discourse.julialang.org/t/override-default-object-display-length-in-repl-env/69246)

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**Author:** [@marerik](https://discourse.julialang.org/u/marerik)\
**Replies:** 7\
**Last updated:** [October 10, 2021, 3:54pm UTC](https://discourse.julialang.org/t/override-default-object-display-length-in-repl-env/69246 "2021-10-10T15:54:28Z")

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If I want to display a large object (vector, array, matrix, etc) in the REPL, it will typically echo/display it, but incompletely with ellipses denoting the undisplayed/suppressed values. Is there a way to override the …

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## [Random Sampler behavior](https://discourse.julialang.org/t/random-sampler-behavior/69512)

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**Author:** [@goncharovdk](https://discourse.julialang.org/u/goncharovdk)\
**Replies:** 4\
**Last updated:** [October 10, 2021, 3:21pm UTC](https://discourse.julialang.org/t/random-sampler-behavior/69512 "2021-10-10T15:21:51Z")

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Hello. I’m now rewriting some Monte Carlo simulation code from Java to Julia. It probably was a bad idea to implement it in Java in the first place, but now I use results calculated by Java implementation to verify the c…

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## [Undef for non-arrays](https://discourse.julialang.org/t/undef-for-non-arrays/69250)

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**Author:** [@goerch](https://discourse.julialang.org/u/goerch)\
**Replies:** 6\
**Last updated:** [October 10, 2021, 3:15pm UTC](https://discourse.julialang.org/t/undef-for-non-arrays/69250 "2021-10-10T15:15:51Z")

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Do we have something similar to undef for non-arrays? Wishful thinking: f() = a::Tuple{Int, Int} where T = 5, undef

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## [How to use one color for a surface?](https://discourse.julialang.org/t/how-to-use-one-color-for-a-surface/69483)

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**Author:** [@Ahmed\_Salih](https://discourse.julialang.org/u/Ahmed_Salih)\
**Replies:** 4\
**Last updated:** [October 10, 2021, 2:51pm UTC](https://discourse.julialang.org/t/how-to-use-one-color-for-a-surface/69483 "2021-10-10T14:51:15Z")

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Hello I am trying to use only one color for a surface, but unfortunately I cannot find any example doing this. The command to generate the surface is simply: surface(rand(5),rand(5),rand(5)) But I cannot find the inp…

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## [Why a === b returns TRUE when a and b are single elements (numbers or strings)](https://discourse.julialang.org/t/why-a-b-returns-true-when-a-and-b-are-single-elements-numbers-or-strings/69510)

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**Author:** [@Giulio\_Benedetti](https://discourse.julialang.org/u/Giulio_Benedetti)\
**Replies:** 6\
**Last updated:** [October 10, 2021, 2:32pm UTC](https://discourse.julialang.org/t/why-a-b-returns-true-when-a-and-b-are-single-elements-numbers-or-strings/69510 "2021-10-10T14:32:09Z")

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The other day I was explaining a friend that when you store the same content into different variables, such as: a = \[1, 2\] b = \[1, 2\] the two objects can be actually distinguished by: a === b false because they are s…

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## [Create a struct with uninitialized fields](https://discourse.julialang.org/t/create-a-struct-with-uninitialized-fields/6967)

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**Author:** [@dfdx](https://discourse.julialang.org/u/dfdx)\
**Replies:** 4\
**Last updated:** [October 10, 2021, 2:08pm UTC](https://discourse.julialang.org/t/create-a-struct-with-uninitialized-fields/6967 "2021-10-10T14:08:06Z")

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Having a mutable struct, e.g.: mutable struct Point x y end is it possible to construct its instance with uninitialized fields and set them later? E.g.: p = create\_uninitialized(Point) # \<-- anything like t…

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## [\[ANN\] DataWrangler: Data transformation tools for analytics](https://discourse.julialang.org/t/ann-datawrangler-data-transformation-tools-for-analytics/69490)

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**Author:** [@viraltux](https://discourse.julialang.org/u/viraltux)\
**Replies:** 2\
**Last updated:** [October 10, 2021, 1:14pm UTC](https://discourse.julialang.org/t/ann-datawrangler-data-transformation-tools-for-analytics/69490 "2021-10-10T13:14:07Z")

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DataWrangler.lj has been created in the process of decoupling functionality from Forecast.jl . The package contains a collection of basic tools to prepare data for analytics and specially so for time series analysis and…

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## [How to put values like today() into a string?](https://discourse.julialang.org/t/how-to-put-values-like-today-into-a-string/69506)

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**Author:** [@leon](https://discourse.julialang.org/u/leon)\
**Replies:** 5\
**Last updated:** [October 10, 2021, 12:32pm UTC](https://discourse.julialang.org/t/how-to-put-values-like-today-into-a-string/69506 "2021-10-10T12:32:49Z")

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For example, if I have a variable like this: A = "Dog"; B = "Cat"; I can do this: C = "I have both $A and $b"; How do I do something like the below and add today’s value, e.g., October 10, 2021? D = “I walked my $A …

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## [Understanding splice!](https://discourse.julialang.org/t/understanding-splice/69497)

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**Author:** [@sransome](https://discourse.julialang.org/u/sransome)\
**Replies:** 3\
**Last updated:** [October 10, 2021, 12:31pm UTC](https://discourse.julialang.org/t/understanding-splice/69497 "2021-10-10T12:31:44Z")

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Hi, I’m having trouble with splice! This works fine d=\[1,3\] splice!(d,2:1,2) julia\> d 3-element Vector{Int64}: 1 2 3 But this does not work… d=\[Date(“2021-01-01”),Date(“2021-03-01”)\] splice!(d,2:1,Date(“2021-…

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## [Dimension problem for variable multiplication in ModelingToolkit.jl](https://discourse.julialang.org/t/dimension-problem-for-variable-multiplication-in-modelingtoolkit-jl/69479)

<div class="topic-metadata">

**Author:** [@PikaPei](https://discourse.julialang.org/u/PikaPei)\
**Replies:** 2\
**Last updated:** [October 10, 2021, 12:11pm UTC](https://discourse.julialang.org/t/dimension-problem-for-variable-multiplication-in-modelingtoolkit-jl/69479 "2021-10-10T12:11:21Z")

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This is what I did: using ModelingToolkit @parameters t @variables a(t) b(t) c\[1:2\](t) # then calculate: (c' \* \[a, b\]) \* c I think (c' \* \[a, b\]) can be a scalar, so the dimension is correct. julia\> size(c' \* \[a, b\]) …

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## [LaTeX commands not working with LaTeXStrings eg \\mathfrak, \\boldsymbol](https://discourse.julialang.org/t/latex-commands-not-working-with-latexstrings-eg-mathfrak-boldsymbol/69448)

<div class="topic-metadata">

**Author:** [@mleprovost](https://discourse.julialang.org/u/mleprovost)\
**Replies:** 3\
**Last updated:** [October 10, 2021, 12:06pm UTC](https://discourse.julialang.org/t/latex-commands-not-working-with-latexstrings-eg-mathfrak-boldsymbol/69448 "2021-10-10T12:06:22Z")

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Hello, Some routines like \\boldsymbol or \\mathfrak don’t work for me with LaTeXStrings, while some others like \\mathsf or \\mathrm do. Is it due to my setup, or is it a limitation of LaTeXStrings? Do you know how to fix …

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## [Why do I get an error if I define the correct type for a function argument?](https://discourse.julialang.org/t/why-do-i-get-an-error-if-i-define-the-correct-type-for-a-function-argument/69498)

<div class="topic-metadata">

**Author:** [@Soldalma](https://discourse.julialang.org/u/Soldalma)\
**Replies:** 4\
**Last updated:** [October 10, 2021, 9:54am UTC](https://discourse.julialang.org/t/why-do-i-get-an-error-if-i-define-the-correct-type-for-a-function-argument/69498 "2021-10-10T09:54:19Z")

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I managed to some code to work but there is something that puzzles me: if I declare the type of a function argument the code does not run and I get an error message. The example below involves three different files (I c…

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