# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1223

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

**Page:** 1224

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## [Combinatorial Optimization with permutation input and black-box function](https://discourse.julialang.org/t/combinatorial-optimization-with-permutation-input-and-black-box-function/70578)

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**Author:** [@duringyear](https://discourse.julialang.org/u/duringyear)\
**Replies:** 5\
**Last updated:** [October 29, 2021, 3:35am UTC](https://discourse.julialang.org/t/combinatorial-optimization-with-permutation-input-and-black-box-function/70578 "2021-10-29T03:35:32Z")

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Hi. I’ve been struggling for nights with combinatorial optimization Input = matrix with permutation. Each row represents unit, and column means visit sequence for each place. e.g) x = \[ 1 2 3 4 ; 2 3 1 4 ; 3 1 2 4 \] …

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## [Extracting the posterior mean and covariance from the object created by "GP" in GaussianProcesses.jl](https://discourse.julialang.org/t/extracting-the-posterior-mean-and-covariance-from-the-object-created-by-gp-in-gaussianprocesses-jl/70543)

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**Author:** [@path-doc](https://discourse.julialang.org/u/path-doc)\
**Replies:** 0\
**Last updated:** [October 28, 2021, 10:21am UTC](https://discourse.julialang.org/t/extracting-the-posterior-mean-and-covariance-from-the-object-created-by-gp-in-gaussianprocesses-jl/70543 "2021-10-28T10:21:24Z")

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As part of a broader Value Function Iteration exercise, I wish to feed the output of predictMVN or predict\_f back into an instantiation of GP. Eg. Suppose we have created an instance gp by feeding GP the usual ingredi…

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## [CI error on nightly](https://discourse.julialang.org/t/ci-error-on-nightly/70589)

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**Author:** [@lmiq](https://discourse.julialang.org/u/lmiq)\
**Replies:** 1\
**Last updated:** [October 29, 2021, 2:09am UTC](https://discourse.julialang.org/t/ci-error-on-nightly/70589 "2021-10-29T02:09:21Z")

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I am getting sort of randomly these errors in the nightly build. Should I worry or report it? \[ Info: Attempting to clone the General registry Cloning registry from "https://github.com/JuliaRegistries/General.git"…

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## [Unicode ⊧ not an operator](https://discourse.julialang.org/t/unicode-not-an-operator/56698)

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**Author:** [@guyvdb](https://discourse.julialang.org/u/guyvdb)\
**Replies:** 6\
**Last updated:** [October 29, 2021, 1:47am UTC](https://discourse.julialang.org/t/unicode-not-an-operator/56698 "2021-10-29T01:47:09Z")

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I wondering if it’s worth filing an issue about the ⊧ unicode character: Julia supports entering it with \\models but it cannot be used as either a variable or an operator (contrary to most other unicode math operator cha…

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## [Partially mutable object](https://discourse.julialang.org/t/partially-mutable-object/70463)

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**Author:** [@whatsthecraic](https://discourse.julialang.org/u/whatsthecraic)\
**Replies:** 5\
**Last updated:** [October 28, 2021, 10:46pm UTC](https://discourse.julialang.org/t/partially-mutable-object/70463 "2021-10-28T22:46:05Z")

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Can you only define some fields in an object constant or immutable, as in C++ class Foo { int x; cont int y; }; ?

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## [Data Cleaning: Split, Combine, Apply?](https://discourse.julialang.org/t/data-cleaning-split-combine-apply/70296)

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**Author:** [@YummyPampers2](https://discourse.julialang.org/u/YummyPampers2)\
**Replies:** 9\
**Last updated:** [October 28, 2021, 10:22pm UTC](https://discourse.julialang.org/t/data-cleaning-split-combine-apply/70296 "2021-10-28T22:22:24Z")

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Greetings Everyone: I have a DF: Grade = \["A", "B","C","D"\] Price = rand(1:.001:500) Name = \["John", "Jim", "Paula", "Ruby"\] Date = \["13/06/2008","17/05/2009", "21/04/2008"\] data = DataFrame(Name,Date, Grade,Price) E…

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## [Error when mapping a CuVector{UnitRange} to index another gpu Array](https://discourse.julialang.org/t/error-when-mapping-a-cuvector-unitrange-to-index-another-gpu-array/70451)

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**Author:** [@ogoid](https://discourse.julialang.org/u/ogoid)\
**Replies:** 8\
**Last updated:** [October 28, 2021, 9:27pm UTC](https://discourse.julialang.org/t/error-when-mapping-a-cuvector-unitrange-to-index-another-gpu-array/70451 "2021-10-28T21:27:46Z")

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I’m running into an error while trying to use a CuVector{UnitRange} as an index to map another CuArray. I’m not sure if it’s a bug or not. I think I can explain it better with this example: using CUDA CUDA.allowscalar(…

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## [My code for cubic spline interpolation plots different image everytime and not smooth](https://discourse.julialang.org/t/my-code-for-cubic-spline-interpolation-plots-different-image-everytime-and-not-smooth/70564)

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**Author:** [@pessoalzy](https://discourse.julialang.org/u/pessoalzy)\
**Replies:** 4\
**Last updated:** [October 28, 2021, 8:12pm UTC](https://discourse.julialang.org/t/my-code-for-cubic-spline-interpolation-plots-different-image-everytime-and-not-smooth/70564 "2021-10-28T20:12:38Z")

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I wrote following code trying to implement a cubic spline interpolation (clamped spline). Every time I run it on jupyter notebook may plot different image. And the plotting is likely not very smooth, which is weird for c…

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## [Behaviour of == on Vectors of vectors](https://discourse.julialang.org/t/behaviour-of-on-vectors-of-vectors/70582)

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**Author:** [@Kruxigt](https://discourse.julialang.org/u/Kruxigt)\
**Replies:** 2\
**Last updated:** [October 28, 2021, 9:22pm UTC](https://discourse.julialang.org/t/behaviour-of-on-vectors-of-vectors/70582 "2021-10-28T21:22:59Z")

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Good evening good folks! Can someone explain the below to me? I haven’t given it that much thought so maybe the answer is trivial…or not? julia\> \[\[1,2\],\[3,4\]\] == \[\[1,2\],\[3,4\]\] true julia\> \[\[1,2\],\[3,4\]\] !== \[\[1,2\],\[3,4\]…

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## [Getting NaNs in the hello world example of Flux](https://discourse.julialang.org/t/getting-nans-in-the-hello-world-example-of-flux/70573)

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**Author:** [@NightMachinary](https://discourse.julialang.org/u/NightMachinary)\
**Replies:** 2\
**Last updated:** [October 28, 2021, 9:07pm UTC](https://discourse.julialang.org/t/getting-nans-in-the-hello-world-example-of-flux/70573 "2021-10-28T21:07:19Z")

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I am just starting with Flux.jl, and well, I tried their Hello World example. However, by slightly changing the input parameters used to generate the training data, the code completely fails and produces NaNs. Here is th…

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## [How can I save a Makie heatmap as PNG with one pixel per matrix element?](https://discourse.julialang.org/t/how-can-i-save-a-makie-heatmap-as-png-with-one-pixel-per-matrix-element/70579)

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**Author:** [@NiclasMattsson](https://discourse.julialang.org/u/NiclasMattsson)\
**Replies:** 1\
**Last updated:** [October 28, 2021, 8:50pm UTC](https://discourse.julialang.org/t/how-can-i-save-a-makie-heatmap-as-png-with-one-pixel-per-matrix-element/70579 "2021-10-28T20:50:33Z")

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For example: using Makie x = rand(300, 400) fig = heatmap(x) Makie.save("out1.png", fig) # 800 x 600 Makie.save("out2.png", fig, px\_per\_unit=1) # 800 x 600 Makie.save("out3.png", fig, resolution=size(x)) # 300 x 400 …

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## [MPLAPACK (multiprecision blas+lapack)](https://discourse.julialang.org/t/mplapack-multiprecision-blas-lapack/70514)

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**Author:** [@JeffreySarnoff](https://discourse.julialang.org/u/JeffreySarnoff)\
**Replies:** 8\
**Last updated:** [October 28, 2021, 8:32pm UTC](https://discourse.julialang.org/t/mplapack-multiprecision-blas-lapack/70514 "2021-10-28T20:32:20Z")

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MPLAPACK works with any of these multiprecision libs: GMP, MPFR+MPC, libquadmath, and David Bailey’s DD/QD library. Here is the user guide and the repository, All BLAS routines are available using multiple precision ar…

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## [FFT is too fast compared to assignment in CUDA](https://discourse.julialang.org/t/fft-is-too-fast-compared-to-assignment-in-cuda/70353)

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**Author:** [@wsshin](https://discourse.julialang.org/u/wsshin)\
**Replies:** 3\
**Last updated:** [October 28, 2021, 8:23pm UTC](https://discourse.julialang.org/t/fft-is-too-fast-compared-to-assignment-in-cuda/70353 "2021-10-28T20:23:29Z")

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FFT is a pretty fast algorithm, but its performance on CUDA seems even comparable to simple element-wise assignment. I am wondering if this is something expected. Here is the contents of a performance test code named t…

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## [Peak finding from a distribution](https://discourse.julialang.org/t/peak-finding-from-a-distribution/70485)

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**Author:** [@newtothis](https://discourse.julialang.org/u/newtothis)\
**Replies:** 9\
**Last updated:** [October 28, 2021, 6:35pm UTC](https://discourse.julialang.org/t/peak-finding-from-a-distribution/70485 "2021-10-28T18:35:09Z")

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I have a distribution as a vector in Julia. I can plot a histogram and/or a kde of for this data, but I want to find the peak values. The naive way in which I am doing it is to plot the histogram and then just retrieve t…

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## [\[BUG\] what does this mean and how can I fix the precompile on MIRT and HDF5?](https://discourse.julialang.org/t/bug-what-does-this-mean-and-how-can-i-fix-the-precompile-on-mirt-and-hdf5/70575)

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**Author:** [@finger1517](https://discourse.julialang.org/u/finger1517)\
**Replies:** 0\
**Last updated:** [October 28, 2021, 6:19pm UTC](https://discourse.julialang.org/t/bug-what-does-this-mean-and-how-can-i-fix-the-precompile-on-mirt-and-hdf5/70575 "2021-10-28T18:19:19Z")

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(@v1.6) pkg\> precompile Precompiling project... ? HDF5 ? MIRTio ? StatsPlots ? MIRT and when I using MIRT module, it will give the error julia\> using MIRT WARNING: could not import HDF5.Group into \_hdf5\_impleme…

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## [Cannot execute Ghostscript (gs): GMT error number = 79](https://discourse.julialang.org/t/cannot-execute-ghostscript-gs-gmt-error-number-79/70531)

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**Author:** [@leon](https://discourse.julialang.org/u/leon)\
**Replies:** 8\
**Last updated:** [October 28, 2021, 6:10pm UTC](https://discourse.julialang.org/t/cannot-execute-ghostscript-gs-gmt-error-number-79/70531 "2021-10-28T18:10:53Z")

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Has anyone seen this error before? It seems that my program is having trouble executing Ghostscript. I’m on a Mac OS system. Error message: psconvert \[ERROR\]: Cannot execute Ghostscript (gs). \*\*ERROR:\*\* LoadError: So…

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## [Failed to precompile CSV due to load error](https://discourse.julialang.org/t/failed-to-precompile-csv-due-to-load-error/70146)

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**Author:** [@Temi-Tory](https://discourse.julialang.org/u/Temi-Tory)\
**Replies:** 3\
**Last updated:** [October 28, 2021, 4:17pm UTC](https://discourse.julialang.org/t/failed-to-precompile-csv-due-to-load-error/70146 "2021-10-28T16:17:59Z")

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Hi, I am trying to read a CSV file to a dataframe. Every time I try to use the CSV.jl package to read csv file. I am greeted with the following error: LoadError: Failed to precompile CSV \[336ed68f-0bac-5ca0-87d4-7b16ca…

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## [\[ANN\] CatmullRom.jl (centripetal splines)](https://discourse.julialang.org/t/ann-catmullrom-jl-centripetal-splines/26755)

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**Author:** [@JeffreySarnoff](https://discourse.julialang.org/u/JeffreySarnoff)\
**Replies:** 0\
**Last updated:** [July 24, 2019, 8:10pm UTC](https://discourse.julialang.org/t/ann-catmullrom-jl-centripetal-splines/26755 "2019-07-24T20:10:15Z")

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CatmullRom.jl is an easily used approach to fast, attractive curvilinear blending. Catmull-Rom splines are a mathematical workhorse of computational graphics, animation and visualization. Applied to a sequence of points,…

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## [\[ANN\] NormalSplines.jl: 1-D Interpolating Normal Splines](https://discourse.julialang.org/t/ann-normalsplines-jl-1-d-interpolating-normal-splines/36811)

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**Author:** [@igorkohan](https://discourse.julialang.org/u/igorkohan)\
**Replies:** 0\
**Last updated:** [March 31, 2020, 6:37pm UTC](https://discourse.julialang.org/t/ann-normalsplines-jl-1-d-interpolating-normal-splines/36811 "2020-03-31T18:37:21Z")

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NormalSplines.jl package implements the normal splines method for interpolating a function based on data of the function values and its first or second derivatives known at a set of points. The normal splines method con…

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## [Using splines in a likelihood](https://discourse.julialang.org/t/using-splines-in-a-likelihood/49340)

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**Author:** [@Ross\_Boylan](https://discourse.julialang.org/u/Ross_Boylan)\
**Replies:** 0\
**Last updated:** [October 30, 2020, 10:47pm UTC](https://discourse.julialang.org/t/using-splines-in-a-likelihood/49340 "2020-10-30T22:47:27Z")

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I am looking to add splines to the type of functions that can go in @formula to support a conditional likelihood model I’ve developed. Once that is working I plan to add automatic smoothing parameter selection. The pac…

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## [Help: OutOfMemoryError()](https://discourse.julialang.org/t/help-outofmemoryerror/70396)

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**Author:** [@Temi-Tory](https://discourse.julialang.org/u/Temi-Tory)\
**Replies:** 6\
**Last updated:** [October 28, 2021, 3:59pm UTC](https://discourse.julialang.org/t/help-outofmemoryerror/70396 "2021-10-28T15:59:59Z")

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Hi I am new to still new to Julia and I have encountered this error and I cant figure out what is causing it and why. Below is my code. The first time I ran this, it was executed fine but after that I keep getting this…

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## [OutOfMemory() when loading a database of images](https://discourse.julialang.org/t/outofmemory-when-loading-a-database-of-images/70523)

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**Author:** [@Ivan](https://discourse.julialang.org/u/Ivan)\
**Replies:** 9\
**Last updated:** [October 28, 2021, 2:40pm UTC](https://discourse.julialang.org/t/outofmemory-when-loading-a-database-of-images/70523 "2021-10-28T14:40:54Z")

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I am trying to work with a database of images (2767 images in total), but I run into an OutOfMemory() error when loading the data. This is how I am doing it: path = string(pwd(), "/Data") list = readdir(path, join = tru…

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## [Accessing type internal fields in package interfaces](https://discourse.julialang.org/t/accessing-type-internal-fields-in-package-interfaces/70263)

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**Author:** [@mkborregaard](https://discourse.julialang.org/u/mkborregaard)\
**Replies:** 14\
**Last updated:** [October 28, 2021, 2:36pm UTC](https://discourse.julialang.org/t/accessing-type-internal-fields-in-package-interfaces/70263 "2021-10-28T14:36:28Z")

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Hi all, we come just from small course where several people have taught several Julia packages to students over the last week. One thing we realized was that some packages naturally assume a workflow in which you consta…

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## [Cannot Install JuliaDB](https://discourse.julialang.org/t/cannot-install-juliadb/53057)

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**Author:** [@PikaPhD](https://discourse.julialang.org/u/PikaPhD)\
**Replies:** 2\
**Last updated:** [October 28, 2021, 1:34pm UTC](https://discourse.julialang.org/t/cannot-install-juliadb/53057 "2021-10-28T13:34:07Z")

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I am trying to install JuliaDB so I can start learning how to use databases in Juila. I am having a conflict with StatsBase. If I understand the error message correctly, JuliaDB requires version 0.13.1 or earlier of Sta…

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## [Indexing an arbitrary array over its last dimension](https://discourse.julialang.org/t/indexing-an-arbitrary-array-over-its-last-dimension/70443)

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**Author:** [@MattSainsbury-Dale](https://discourse.julialang.org/u/MattSainsbury-Dale)\
**Replies:** 4\
**Last updated:** [October 28, 2021, 1:31pm UTC](https://discourse.julialang.org/t/indexing-an-arbitrary-array-over-its-last-dimension/70443 "2021-10-28T13:31:17Z")

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I am trying to index over the last dimension of an array of unknown dimension. Please see the following MWE for a 2-dimensional array: a = rand(2, 4) indices = \[1:2, 3:4\] colons = repeat(\[:\], ndims(a) - 1) v …

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## [Question on Defining Functions Inside Structs](https://discourse.julialang.org/t/question-on-defining-functions-inside-structs/70532)

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**Author:** [@TI36XPro](https://discourse.julialang.org/u/TI36XPro)\
**Replies:** 8\
**Last updated:** [October 28, 2021, 1:20pm UTC](https://discourse.julialang.org/t/question-on-defining-functions-inside-structs/70532 "2021-10-28T13:20:31Z")

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I noticed in this video here that several constructors for the struct are defined inside the struct block itself. I’ve not personally done this to date, it just didn’t occur to me. I’ve always defined alternate construct…

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## [Help with deploying documentation with GitHub Actions](https://discourse.julialang.org/t/help-with-deploying-documentation-with-github-actions/63872)

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**Author:** [@RaulDurand](https://discourse.julialang.org/u/RaulDurand)\
**Replies:** 6\
**Last updated:** [October 28, 2021, 12:58pm UTC](https://discourse.julialang.org/t/help-with-deploying-documentation-with-github-actions/63872 "2021-10-28T12:58:32Z")

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I followed all steps in the tutorial below to deploy my unregistered package documentation. However, the gh-pages branch is not updated. It only displays a default GitHub page. What am I missing? I enabled Actions an…

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## [Weird Schrodinger solution by DifferentialEquations.jl versus time interval](https://discourse.julialang.org/t/weird-schrodinger-solution-by-differentialequations-jl-versus-time-interval/70542)

<div class="topic-metadata">

**Author:** [@TravellingLight6](https://discourse.julialang.org/u/TravellingLight6)\
**Replies:** 2\
**Last updated:** [October 28, 2021, 12:53pm UTC](https://discourse.julialang.org/t/weird-schrodinger-solution-by-differentialequations-jl-versus-time-interval/70542 "2021-10-28T12:53:16Z")

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Suppose we want to solve a simple schrodinger equation under columb potential,namely, \\Psi''=(V-E)\\Psi and V(r)=-\\frac{1}{r}, The wavefunction u(r) of ground state is: \\sim a\\times r\\cdot e^{-br} which should be the ex…

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## [How to use custom sysimage if cannot set flags on Julia startup](https://discourse.julialang.org/t/how-to-use-custom-sysimage-if-cannot-set-flags-on-julia-startup/70482)

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**Author:** [@Bakaburg1](https://discourse.julialang.org/u/Bakaburg1)\
**Replies:** 8\
**Last updated:** [October 28, 2021, 11:46am UTC](https://discourse.julialang.org/t/how-to-use-custom-sysimage-if-cannot-set-flags-on-julia-startup/70482 "2021-10-28T11:46:49Z")

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Hello, I have a custom Julia package (only local) inside an R project. I’m interacting with the Julia package via https://github.com/stefan-m-lenz/JuliaConnectoR. I’d like to precompile this package and its functions s…

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## [Print to terminal instead of to Jupyter Notebook](https://discourse.julialang.org/t/print-to-terminal-instead-of-to-jupyter-notebook/70391)

<div class="topic-metadata">

**Author:** [@ismedina](https://discourse.julialang.org/u/ismedina)\
**Replies:** 4\
**Last updated:** [October 28, 2021, 10:33am UTC](https://discourse.julialang.org/t/print-to-terminal-instead-of-to-jupyter-notebook/70391 "2021-10-28T10:33:40Z")

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I have a function that does some calculation and prints the ongoing progress, say function f() for i in 1:10 sleep(0.1) println(i) end end When running it in a Jupyter Notebook, the output …

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