# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1582

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

**Page:** 1583

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## [ANN: Geophysics.jl](https://discourse.julialang.org/t/ann-geophysics-jl/49097)

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**Author:** [@tk3369](https://discourse.julialang.org/u/tk3369)\
**Replies:** 7\
**Last updated:** [November 4, 2020, 6:42pm UTC](https://discourse.julialang.org/t/ann-geophysics-jl/49097 "2020-11-04T18:42:05Z")

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Hi! New package: Geophysics.jl I’m posting this announcement on behalf of the author, who told me that he’s looking for open source contribution. The author is not here but active on Reddit. If you are interested in th…

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## [Is it possible to call C# functions with Julia?](https://discourse.julialang.org/t/is-it-possible-to-call-c-functions-with-julia/18979)

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**Author:** [@cloudostrich](https://discourse.julialang.org/u/cloudostrich)\
**Replies:** 6\
**Last updated:** [November 4, 2020, 6:27pm UTC](https://discourse.julialang.org/t/is-it-possible-to-call-c-functions-with-julia/18979 "2020-11-04T18:27:16Z")

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Hi all, I am new to Julia, coming from python, and very excited to learn this wonderful language. Like to ask is there a library for Julia to call C# functions (in .Net framework) from Julia, like how Cxx.jl calls C++ f…

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## [Can't instantiate project with two unregistered packages](https://discourse.julialang.org/t/cant-instantiate-project-with-two-unregistered-packages/36703)

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**Author:** [@essenciary](https://discourse.julialang.org/u/essenciary)\
**Replies:** 8\
**Last updated:** [November 4, 2020, 3:45pm UTC](https://discourse.julialang.org/t/cant-instantiate-project-with-two-unregistered-packages/36703 "2020-11-04T15:45:51Z")

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I’m not sure what I’m missing but I’m having problems setting up a Julia project, as follows: I started the project on my Mac the project uses two unregistered packages: GitHub - GenieFramework/Stipple.jl: The reactiv…

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## [CSV Error - Feather Error](https://discourse.julialang.org/t/csv-error-feather-error/49309)

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**Author:** [@orthoeng](https://discourse.julialang.org/u/orthoeng)\
**Replies:** 7\
**Last updated:** [November 4, 2020, 3:11pm UTC](https://discourse.julialang.org/t/csv-error-feather-error/49309 "2020-11-04T15:11:33Z")

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I’m very new to Julia Programming. I have a folder of CSV files (14) that I join to one big data frame and I’m trying to save the big CSV. (rows - 262673020 x columns - 77) when I use CSV.write - I get this ERROR: Bound…

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## [Proposal: working with larger than memory data in hdf5 format using HDF5Arrays (implementation of DiskArrays.jl for HDF5)](https://discourse.julialang.org/t/proposal-working-with-larger-than-memory-data-in-hdf5-format-using-hdf5arrays-implementation-of-diskarrays-jl-for-hdf5/48997)

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**Author:** [@Luapulu](https://discourse.julialang.org/u/Luapulu)\
**Replies:** 11\
**Last updated:** [November 4, 2020, 2:36pm UTC](https://discourse.julialang.org/t/proposal-working-with-larger-than-memory-data-in-hdf5-format-using-hdf5arrays-implementation-of-diskarrays-jl-for-hdf5/48997 "2020-11-04T14:36:21Z")

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Proposal Often, I have data, that is larger than memory and I’d like to be able to work with the hdf5 file format in julia. I propose we/I write a package (HDF5Arrays.jl) to address some of the following use cases (in ad…

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## [How can I create a DataFrame with many columns programatically?](https://discourse.julialang.org/t/how-can-i-create-a-dataframe-with-many-columns-programatically/49559)

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**Author:** [@Juan](https://discourse.julialang.org/u/Juan)\
**Replies:** 5\
**Last updated:** [November 4, 2020, 2:02pm UTC](https://discourse.julialang.org/t/how-can-i-create-a-dataframe-with-many-columns-programatically/49559 "2020-11-04T14:02:15Z")

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If I want to create a DataFrame with just 2 columns I can do: DataFrame(a=rand(Normal(0, 1), 10), b=rand(Normal(0, 1), 10)) But what if I want to create a DataFrame with hundreds or thousands of columns with a given …

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## [Plots.jl: Default label size](https://discourse.julialang.org/t/plots-jl-default-label-size/49454)

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**Author:** [@willtebbutt](https://discourse.julialang.org/u/willtebbutt)\
**Replies:** 3\
**Last updated:** [November 4, 2020, 1:45pm UTC](https://discourse.julialang.org/t/plots-jl-default-label-size/49454 "2020-11-04T13:45:13Z")

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Firstly, thanks for incorporating PGFPlotsX into Plots – it’s a really fantastic thing to have available. Looking through the tikz generated when I savefig, I notice that most of the font sizes are hard-coded to 8pt by …

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## [How to consume data from generator expression](https://discourse.julialang.org/t/how-to-consume-data-from-generator-expression/49538)

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**Author:** [@MikeErd](https://discourse.julialang.org/u/MikeErd)\
**Replies:** 4\
**Last updated:** [November 4, 2020, 1:35pm UTC](https://discourse.julialang.org/t/how-to-consume-data-from-generator-expression/49538 "2020-11-04T13:35:40Z")

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Hi all, I’m using Julia 1.5.2 and Combinatorics v1.0.2. I tried the following combinatorics exercise. First level: Get all combinations selecting 4 elements out of 8 available elements, without repetition (meaning ea…

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## [How to use \`heatmap\` in GR.jl](https://discourse.julialang.org/t/how-to-use-heatmap-in-gr-jl/49507)

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**Author:** [@kapple](https://discourse.julialang.org/u/kapple)\
**Replies:** 17\
**Last updated:** [November 4, 2020, 12:44pm UTC](https://discourse.julialang.org/t/how-to-use-heatmap-in-gr-jl/49507 "2020-11-04T12:44:09Z")

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Why does this not work? julia\> using GR julia\> heatmap(\[1 2\], \[3 4\], \[5 6; 7 8\]) ERROR: AssertionError: length(x) == dimx + 1 && length(y) == dimy + 1 Stacktrace: \[1\] nonuniformcellarray(::Array{Int64,2}, ::Array{Int6…

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## [Problems in installing package MAT](https://discourse.julialang.org/t/problems-in-installing-package-mat/49547)

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**Author:** [@gcalajo](https://discourse.julialang.org/u/gcalajo)\
**Replies:** 3\
**Last updated:** [November 4, 2020, 9:08am UTC](https://discourse.julialang.org/t/problems-in-installing-package-mat/49547 "2020-11-04T09:08:37Z")

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Hi I am trying to download the package MAT in Julia 0.64 with the command Pkg.add(“MAT”) I did it other times in other PC with no issues but this time is giving me the following error: ERROR: SystemError: realpath: No…

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## [Can I impose a super type for an existing struct?](https://discourse.julialang.org/t/can-i-impose-a-super-type-for-an-existing-struct/49460)

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**Author:** [@giancarloantonucci](https://discourse.julialang.org/u/giancarloantonucci)\
**Replies:** 15\
**Last updated:** [November 4, 2020, 8:53am UTC](https://discourse.julialang.org/t/can-i-impose-a-super-type-for-an-existing-struct/49460 "2020-11-04T08:53:51Z")

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As per title, can I impose my abstract type MyAbstractType end as a/the supertype for a pre-existing struct/type ExistingStruct coming from, say, a separate module? I just want ExistingStruct \<: MyAbstractType to ret…

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## [Overloading vectorization?](https://discourse.julialang.org/t/overloading-vectorization/49526)

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**Author:** [@bcsj](https://discourse.julialang.org/u/bcsj)\
**Replies:** 9\
**Last updated:** [November 4, 2020, 8:32am UTC](https://discourse.julialang.org/t/overloading-vectorization/49526 "2020-11-04T08:32:42Z")

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So say I have a function, e.g. f(x,y) = x\*y and two arrays a=\[1,2\]; b=\[3,4\], then I can perform f element-wise by calling f.(a,b). But now f is a more complicated operation, f.(a,b) still works, but say I can write anot…

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## [Weave unable to execute Maxima.jl](https://discourse.julialang.org/t/weave-unable-to-execute-maxima-jl/49560)

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**Author:** [@brett\_knoss](https://discourse.julialang.org/u/brett_knoss)\
**Replies:** 0\
**Last updated:** [November 4, 2020, 2:22am UTC](https://discourse.julialang.org/t/weave-unable-to-execute-maxima-jl/49560 "2020-11-04T02:22:05Z")

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When I try to Weave a Julia Markdown with Maxima.jl, it ends up not starting. using Maxima It just stays on the first block of code.

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## [How to realize this multithreading function](https://discourse.julialang.org/t/how-to-realize-this-multithreading-function/49537)

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**Author:** [@bluefog](https://discourse.julialang.org/u/bluefog)\
**Replies:** 2\
**Last updated:** [November 4, 2020, 1:07am UTC](https://discourse.julialang.org/t/how-to-realize-this-multithreading-function/49537 "2020-11-04T01:07:45Z")

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Core 1 is constantly calculating x, and core 2 is constantly taking the value of X But did not debug through X, no shared program has been in the core 1 loop, please give me some advice, thank you #====================…

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## [How to create strings combining all letters?](https://discourse.julialang.org/t/how-to-create-strings-combining-all-letters/49550)

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**Author:** [@Juan](https://discourse.julialang.org/u/Juan)\
**Replies:** 6\
**Last updated:** [November 4, 2020, 12:14am UTC](https://discourse.julialang.org/t/how-to-create-strings-combining-all-letters/49550 "2020-11-04T00:14:22Z")

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Hello. I’m trying to learn Julia by replicating simple R code in Julia but I’m not even able to create a toy example :anguished: Let me ask some simple question. In R there is a function letters, which gives you a vec…

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## [Local machine and Intranet DB up to date data formats - which one?](https://discourse.julialang.org/t/local-machine-and-intranet-db-up-to-date-data-formats-which-one/49557)

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**Author:** [@teriiju](https://discourse.julialang.org/u/teriiju)\
**Replies:** 0\
**Last updated:** [November 4, 2020, 12:01am UTC](https://discourse.julialang.org/t/local-machine-and-intranet-db-up-to-date-data-formats-which-one/49557 "2020-11-04T00:01:43Z")

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Hi, New to Julia : I would like to know what are the first 2 (or more) file formats recommanded to store data, strings/numbers (Multmedia support not needed): A) - for a local use, on standard workstation, if a txt t…

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## [Create variables in a loop](https://discourse.julialang.org/t/create-variables-in-a-loop/49549)

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**Author:** [@Albert\_Zevelev](https://discourse.julialang.org/u/Albert_Zevelev)\
**Replies:** 10\
**Last updated:** [November 3, 2020, 11:14pm UTC](https://discourse.julialang.org/t/create-variables-in-a-loop/49549 "2020-11-03T23:14:16Z")

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Suppose I wanna create some routine econ variables: using FredData; const f = Fred("Personal api\_key"); # d = get\_data(f, "GDP"); y=d.df\[:,4\] d = get\_data(f, "PCEC"); c=d.df\[:,4\] d = get\_data(f, "GPDI"); i=d…

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## [Faces & Vertices of N Linear Constraints](https://discourse.julialang.org/t/faces-vertices-of-n-linear-constraints/49347)

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**Author:** [@anon92994695](https://discourse.julialang.org/u/anon92994695)\
**Replies:** 15\
**Last updated:** [November 3, 2020, 11:07pm UTC](https://discourse.julialang.org/t/faces-vertices-of-n-linear-constraints/49347 "2020-11-03T23:07:29Z")

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Here’s a fun one, so instead of doing what I normally do(hacking away at code), I figured I’d ask if people had tools to recommend for solving a problem. I know you people working in optimization and geometry live in thi…

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## [Convert a float into a string](https://discourse.julialang.org/t/convert-a-float-into-a-string/49513)

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**Author:** [@teriiju](https://discourse.julialang.org/u/teriiju)\
**Replies:** 25\
**Last updated:** [November 3, 2020, 10:26pm UTC](https://discourse.julialang.org/t/convert-a-float-into-a-string/49513 "2020-11-03T22:26:00Z")

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Hi, Is it possible to convert a float number into a string ? i.e. 32.234565 ()number into “32.234565” (string) or this works only with integers ? Thanks

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## [Which small, cheap, low power, system-on-chip computers run Julia?](https://discourse.julialang.org/t/which-small-cheap-low-power-system-on-chip-computers-run-julia/31379)

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**Author:** [@robblackwell](https://discourse.julialang.org/u/robblackwell)\
**Replies:** 5\
**Last updated:** [November 3, 2020, 9:54pm UTC](https://discourse.julialang.org/t/which-small-cheap-low-power-system-on-chip-computers-run-julia/31379 "2020-11-03T21:54:52Z")

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I’ve been demonstrating some Julia code for scientific data processing running on a Raspberry Pi. My message that the same code works on both high performance compute clusters and low end embedded systems seems power…

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## [Pull request for printing Array{\<:Real,1}](https://discourse.julialang.org/t/pull-request-for-printing-array-real-1/49013)

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**Author:** [@CameronBieganek](https://discourse.julialang.org/u/CameronBieganek)\
**Replies:** 2\
**Last updated:** [November 3, 2020, 9:25pm UTC](https://discourse.julialang.org/t/pull-request-for-printing-array-real-1/49013 "2020-11-03T21:25:01Z")

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A while ago I saw a pull request that changed printing so that Array{\<:Real,1} would print as Array{\<:Real,1}, instead of like this: julia\> Array{\<:Real,1} Array{var"#s17",1} where var"#s17"\<:Real But I can’t find that…

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## [Implement Mixed Models with sparse X and Z matrices](https://discourse.julialang.org/t/implement-mixed-models-with-sparse-x-and-z-matrices/49539)

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**Author:** [@Antonina\_Klyuyeva](https://discourse.julialang.org/u/Antonina_Klyuyeva)\
**Replies:** 7\
**Last updated:** [November 3, 2020, 7:48pm UTC](https://discourse.julialang.org/t/implement-mixed-models-with-sparse-x-and-z-matrices/49539 "2020-11-03T19:48:53Z")

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Hi there, I use mixed models on a large file (500000 rows). My model formula looks like this: Y ~ 0 + num1:factor1 + num1:factor2 + num2:factor3 + factor4 + (0 + num3|subject) + (0 + num4|subject) + (1|subject), whe…

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## [Divrem maximum precision for the remain](https://discourse.julialang.org/t/divrem-maximum-precision-for-the-remain/49510)

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**Author:** [@teriiju](https://discourse.julialang.org/u/teriiju)\
**Replies:** 14\
**Last updated:** [November 3, 2020, 7:30pm UTC](https://discourse.julialang.org/t/divrem-maximum-precision-for-the-remain/49510 "2020-11-03T19:30:14Z")

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Hi, Can divrem return a remainder with a higher digit precision ? more digits after the dot… or is it just meant to round the remainder to 2 digits most always… Thanks

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## [How to prohibit assignment to a variable in a function?](https://discourse.julialang.org/t/how-to-prohibit-assignment-to-a-variable-in-a-function/49544)

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**Author:** [@Qiyamah](https://discourse.julialang.org/u/Qiyamah)\
**Replies:** 2\
**Last updated:** [November 3, 2020, 6:57pm UTC](https://discourse.julialang.org/t/how-to-prohibit-assignment-to-a-variable-in-a-function/49544 "2020-11-03T18:57:28Z")

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function f(x::Int) const y = 5 #some code... y =2 # I want this line to throw "ERROR: invalid redefinition of constant y" x+y end Instead it throws: ERROR: syntax: unsupported const declaration on …

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## [How to calibrate age-structured SIR model on mono-dimensional data?](https://discourse.julialang.org/t/how-to-calibrate-age-structured-sir-model-on-mono-dimensional-data/49532)

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**Author:** [@PietroMonticone](https://discourse.julialang.org/u/PietroMonticone)\
**Replies:** 1\
**Last updated:** [November 3, 2020, 6:56pm UTC](https://discourse.julialang.org/t/how-to-calibrate-age-structured-sir-model-on-mono-dimensional-data/49532 "2020-11-03T18:56:59Z")

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Consider the following age-structured SIR model I’ve written in the DifferentialEquations.jl framework: # Import using DifferentialEquations, DiffEqBayes # Model parameters β = \[0.1, 0.2, 0.3\] γ = 0.15 𝒫 = vcat(\[β, γ\]…

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## [Plots + plotlyjs + logscale + savefig](https://discourse.julialang.org/t/plots-plotlyjs-logscale-savefig/49548)

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**Author:** [@Oto\_Brzobohaty](https://discourse.julialang.org/u/Oto_Brzobohaty)\
**Replies:** 0\
**Last updated:** [November 3, 2020, 6:50pm UTC](https://discourse.julialang.org/t/plots-plotlyjs-logscale-savefig/49548 "2020-11-03T18:50:00Z")

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I have used Plots + with plotlyjs() backend and I am bit confused with the output of savefig() Please compare the following figure This one is is produced by savefig() This one is screenshot form VS Code plot pane …

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## [Is there an outline for Julia Markdown?](https://discourse.julialang.org/t/is-there-an-outline-for-julia-markdown/49545)

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**Author:** [@brett\_knoss](https://discourse.julialang.org/u/brett_knoss)\
**Replies:** 0\
**Last updated:** [November 3, 2020, 6:20pm UTC](https://discourse.julialang.org/t/is-there-an-outline-for-julia-markdown/49545 "2020-11-03T18:20:12Z")

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When I run a Markdown in VS Code, I’m able to find an outline. This makes it easy to find materials, but I’m not able to find the same feature in Julia Markdown. Is there an outline avaliable? I might also want to set…

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## [IJulia (not found in project or manifest)](https://discourse.julialang.org/t/ijulia-not-found-in-project-or-manifest/49490)

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**Author:** [@acycliq](https://discourse.julialang.org/u/acycliq)\
**Replies:** 2\
**Last updated:** [November 3, 2020, 6:00pm UTC](https://discourse.julialang.org/t/ijulia-not-found-in-project-or-manifest/49490 "2020-11-03T18:00:51Z")

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Hi all That is the very first time I try to use Julia. I already have a Anaconda Python v3 distribution (Windows 10) installed on my pc and I want to integrate it with Julia This is what I have done Downloaded julia-…

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## [Type unstable function returning a tuple](https://discourse.julialang.org/t/type-unstable-function-returning-a-tuple/49493)

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**Author:** [@Bigorneau](https://discourse.julialang.org/u/Bigorneau)\
**Replies:** 34\
**Last updated:** [November 3, 2020, 5:46pm UTC](https://discourse.julialang.org/t/type-unstable-function-returning-a-tuple/49493 "2020-11-03T17:46:13Z")

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Good evening, I have been facing a (slightly) annoying type inference issue when writing a function which returns a tuple. Here is a minimal working example: f(v, ::Val{N}) where {N} = ntuple(i -\> sum(v\[1\]), N) # type…

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## [Eigvals() results being slightly different when Distributed.jl are used](https://discourse.julialang.org/t/eigvals-results-being-slightly-different-when-distributed-jl-are-used/49516)

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**Author:** [@zhaiyusci](https://discourse.julialang.org/u/zhaiyusci)\
**Replies:** 2\
**Last updated:** [November 3, 2020, 4:51pm UTC](https://discourse.julialang.org/t/eigvals-results-being-slightly-different-when-distributed-jl-are-used/49516 "2020-11-03T16:51:30Z")

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Hi friends, recently I am working on some eigen problems in quantum physics. I need to construct and diagonalize quite a few symmetric real matrices so I am using Distributed, the standard library. See a minimal example…

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