# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1075

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

**Page:** 1076

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## [Nested gradient computations with differential equation solver](https://discourse.julialang.org/t/nested-gradient-computations-with-differential-equation-solver/79042)

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**Author:** [@quentinf00](https://discourse.julialang.org/u/quentinf00)\
**Replies:** 9\
**Last updated:** [April 6, 2022, 8:10am UTC](https://discourse.julialang.org/t/nested-gradient-computations-with-differential-equation-solver/79042 "2022-04-06T08:10:05Z")

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Hi, I am exploring the possibilities of combining Julia’s differential equations solvers and automatic differentiation capabilities, and I am stuck while trying to backpropagate twice through an ode solver. Here is some…

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## [Convert Date difference to Float64](https://discourse.julialang.org/t/convert-date-difference-to-float64/79016)

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**Author:** [@ryofurue](https://discourse.julialang.org/u/ryofurue)\
**Replies:** 8\
**Last updated:** [April 6, 2022, 9:10am UTC](https://discourse.julialang.org/t/convert-date-difference-to-float64/79016 "2022-04-06T09:10:10Z")

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\[Edit: Sorry, folks, I’ve realized that I simplified my actual problem too much. The solutions you kindly offered are solutions to my example, but they don’t work for my actual problem! To avoid confusion, I post a mor…

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## [Come join the Julia Zulip chat!](https://discourse.julialang.org/t/come-join-the-julia-zulip-chat/36070)

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**Author:** [@Mason](https://discourse.julialang.org/u/Mason)\
**Replies:** 28\
**Last updated:** [April 6, 2022, 7:55am UTC](https://discourse.julialang.org/t/come-join-the-julia-zulip-chat/36070 "2022-04-06T07:55:24Z")

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Hey everyone, just wanted to advertise the Julia Zulip chat server. I think it’s great but there’s a chicken and egg problem where it’s hard to convince people to use it because there’s currently few active users. Zulip…

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## [Dropmissing(!) is undefined for GroupedDataFrames](https://discourse.julialang.org/t/dropmissing-is-undefined-for-groupeddataframes/79037)

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**Author:** [@Joseph\_Bradley](https://discourse.julialang.org/u/Joseph_Bradley)\
**Replies:** 15\
**Last updated:** [April 6, 2022, 7:35am UTC](https://discourse.julialang.org/t/dropmissing-is-undefined-for-groupeddataframes/79037 "2022-04-06T07:35:54Z")

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Hi, The following code throws an error: df.ticker = vcat(\["AAPL" for i in 1:10\], \["TSLA" for i in 1:10\]) df.prices = vcat(rand(19), missing) gdf = groupby(df, :ticker) dropmissing!(gdf) The only solution I have at …

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## [Method Error and Corpus Creation](https://discourse.julialang.org/t/method-error-and-corpus-creation/78917)

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**Author:** [@edbezci](https://discourse.julialang.org/u/edbezci)\
**Replies:** 1\
**Last updated:** [April 6, 2022, 6:35am UTC](https://discourse.julialang.org/t/method-error-and-corpus-creation/78917 "2022-04-06T06:35:05Z")

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Hello, I am new Julia and trying to train a basic SVM model for multiclass text classification in Julia. My dataset has around 75K rows and 2 columns (text and label). The context of the dataset is the abstracts of scie…

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## [Researcher at Hydro-Quebec](https://discourse.julialang.org/t/researcher-at-hydro-quebec/75983)

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**Author:** [@Balinus](https://discourse.julialang.org/u/Balinus)\
**Replies:** 4\
**Last updated:** [April 6, 2022, 3:38am UTC](https://discourse.julialang.org/t/researcher-at-hydro-quebec/75983 "2022-04-06T03:38:45Z")

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Hello, A good job is posted at Hydro-Quebec, in Montreal region. Aimed at HPC, AI, distributed computing. Basic French language required.

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## [Fortran to Julia struct](https://discourse.julialang.org/t/fortran-to-julia-struct/79081)

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**Author:** [@james3](https://discourse.julialang.org/u/james3)\
**Replies:** 1\
**Last updated:** [April 6, 2022, 3:10am UTC](https://discourse.julialang.org/t/fortran-to-julia-struct/79081 "2022-04-06T03:10:12Z")

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I’m having some difficulty calling some Fortran code from Julia. I have some Fortran code like the following module fortranjulia use, intrinsic :: iso\_c\_binding implicit none type, bind(c) :: m\_t integer(c…

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## [Interpolations over Shape Fitted Grids](https://discourse.julialang.org/t/interpolations-over-shape-fitted-grids/79033)

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**Author:** [@Whyborn](https://discourse.julialang.org/u/Whyborn)\
**Replies:** 3\
**Last updated:** [April 6, 2022, 12:04am UTC](https://discourse.julialang.org/t/interpolations-over-shape-fitted-grids/79033 "2022-04-06T00:04:23Z")

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I am trying to interpolate on a grid that is body fitted (in a Computational Fluid Dynamics context). The grid cannot be simply described by vectors describing the grid spacing in each dimensions, instead the points are …

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## [How do I define a dictionary type for tuples with functions as elements?](https://discourse.julialang.org/t/how-do-i-define-a-dictionary-type-for-tuples-with-functions-as-elements/79038)

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**Author:** [@Soldalma](https://discourse.julialang.org/u/Soldalma)\
**Replies:** 2\
**Last updated:** [April 6, 2022, 12:00am UTC](https://discourse.julialang.org/t/how-do-i-define-a-dictionary-type-for-tuples-with-functions-as-elements/79038 "2022-04-06T00:00:46Z")

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I want to create a dictionary whose entries are 2-tuples where the second element is a function. One such dictionary would be: di1 = Dict(:C =\> (\[:AA\], identity)) However, its type does not match what I want: typeof(…

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## [Postdoc position available in HPC for Earthquake Cycle Models at the University of Oregon](https://discourse.julialang.org/t/postdoc-position-available-in-hpc-for-earthquake-cycle-models-at-the-university-of-oregon/79074)

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**Author:** [@Brittany](https://discourse.julialang.org/u/Brittany)\
**Replies:** 0\
**Last updated:** [April 5, 2022, 9:25pm UTC](https://discourse.julialang.org/t/postdoc-position-available-in-hpc-for-earthquake-cycle-models-at-the-university-of-oregon/79074 "2022-04-05T21:25:29Z")

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This postdoc position will involve research in high-performance computing techniques for numerical partial differential equations (PDEs) and their use in large-scale earthquake simulations in complex fault networks. The …

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## [Solving differential equations with derivatives on both sides of the equation](https://discourse.julialang.org/t/solving-differential-equations-with-derivatives-on-both-sides-of-the-equation/79070)

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**Author:** [@CameronBieganek](https://discourse.julialang.org/u/CameronBieganek)\
**Replies:** 4\
**Last updated:** [April 5, 2022, 9:21pm UTC](https://discourse.julialang.org/t/solving-differential-equations-with-derivatives-on-both-sides-of-the-equation/79070 "2022-04-05T21:21:22Z")

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I have two coupled, first order, non-linear ODEs that I’m trying to solve. However, both of the two equations contain additional derivatives on the right-hand sides of the equation (and there don’t seem to be any obvious…

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## [Default values for nested struct array](https://discourse.julialang.org/t/default-values-for-nested-struct-array/79072)

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**Author:** [@james3](https://discourse.julialang.org/u/james3)\
**Replies:** 1\
**Last updated:** [April 5, 2022, 9:08pm UTC](https://discourse.julialang.org/t/default-values-for-nested-struct-array/79072 "2022-04-05T21:08:56Z")

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I can’t work out how to specify default values for a struct array that is nested. I have one struct a\_t which specifies default values. I have a MVector of type a\_t in the struct b\_t. The following code fails. I want the…

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## [Automatic Speech Recognition in Julia](https://discourse.julialang.org/t/automatic-speech-recognition-in-julia/79003)

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**Author:** [@jbrea](https://discourse.julialang.org/u/jbrea)\
**Replies:** 2\
**Last updated:** [April 5, 2022, 8:13pm UTC](https://discourse.julialang.org/t/automatic-speech-recognition-in-julia/79003 "2022-04-05T20:13:44Z")

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Does anyone have (or work on) an implementation of modern automatic speech recognition tools like conformers or wav2vec2.0 in one of Julia’s deep learning frameworks Flux/Knet/Avalon? Ideally pretrained on LibriSpeech …

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## [Using Intel LLVM compiler with Julia](https://discourse.julialang.org/t/using-intel-llvm-compiler-with-julia/79065)

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**Author:** [@duan](https://discourse.julialang.org/u/duan)\
**Replies:** 6\
**Last updated:** [April 5, 2022, 6:51pm UTC](https://discourse.julialang.org/t/using-intel-llvm-compiler-with-julia/79065 "2022-04-05T18:51:56Z")

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Since Intel C/C++ compiler has adopted LLVM, is there a way to tell Julia to use Intel compiler?

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## [Why is the profile view so scrunched up to the right?](https://discourse.julialang.org/t/why-is-the-profile-view-so-scrunched-up-to-the-right/79063)

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**Author:** [@PetrKryslUCSD](https://discourse.julialang.org/u/PetrKryslUCSD)\
**Replies:** 7\
**Last updated:** [April 5, 2022, 6:25pm UTC](https://discourse.julialang.org/t/why-is-the-profile-view-so-scrunched-up-to-the-right/79063 "2022-04-05T18:25:21Z")

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What can be done?

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## [Precision error in Nbody simulation](https://discourse.julialang.org/t/precision-error-in-nbody-simulation/79061)

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**Author:** [@staufenbach](https://discourse.julialang.org/u/staufenbach)\
**Replies:** 11\
**Last updated:** [April 5, 2022, 6:13pm UTC](https://discourse.julialang.org/t/precision-error-in-nbody-simulation/79061 "2022-04-05T18:13:02Z")

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Hi, I’m currently writing a Nbody simulation using the Barnes-Hut algorithm. In order to validate what i wrote, i want to compare it to the brute force calculation. (setting the theta parameter in BH makes it degenerate…

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## [Julia Gender Inclusive coffee meet-up with Eleanor Jayawant](https://discourse.julialang.org/t/julia-gender-inclusive-coffee-meet-up-with-eleanor-jayawant/79062)

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**Author:** [@kimauth](https://discourse.julialang.org/u/kimauth)\
**Replies:** 0\
**Last updated:** [April 5, 2022, 4:41pm UTC](https://discourse.julialang.org/t/julia-gender-inclusive-coffee-meet-up-with-eleanor-jayawant/79062 "2022-04-05T16:41:21Z")

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“How we can use Julia to help us understand signalling in cancer” Hey everyone, Julia Gender Inclusive invites you to the next coffee meetup on 10th of April at 11AM EDT / 3pm UTC / 5pm CEST / 8:30 pm IST! Sign-up here…

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## [One example from \`GPU programming in Julia | Workshop | JuliaCon 2021\`](https://discourse.julialang.org/t/one-example-from-gpu-programming-in-julia-workshop-juliacon-2021/79060)

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**Author:** [@DennisFang](https://discourse.julialang.org/u/DennisFang)\
**Replies:** 0\
**Last updated:** [April 5, 2022, 4:21pm UTC](https://discourse.julialang.org/t/one-example-from-gpu-programming-in-julia-workshop-juliacon-2021/79060 "2022-04-05T16:21:51Z")

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When I run the following example from the Workshop, the result is false in my computer. function my\_sum(a::AbstractArray{T}) where {T} b = CUDA.zeros(T, 1) kernel = @cuda launch=false reduce\_grid\_atomic\_shmem(+…

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## [How to find most frequent element in an array?](https://discourse.julialang.org/t/how-to-find-most-frequent-element-in-an-array/79056)

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**Author:** [@Luigi\_Marongiu](https://discourse.julialang.org/u/Luigi_Marongiu)\
**Replies:** 7\
**Last updated:** [April 5, 2022, 3:34pm UTC](https://discourse.julialang.org/t/how-to-find-most-frequent-element-in-an-array/79056 "2022-04-05T15:34:12Z")

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Hello is there a simple way to find the most frequent element in an array? arr = \[1, 3, 2, 1, 4, 1\] # answer should be \`1\`

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## [How to create data frame from saved vectors in julia 1.7?](https://discourse.julialang.org/t/how-to-create-data-frame-from-saved-vectors-in-julia-1-7/79046)

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**Author:** [@Luigi\_Marongiu](https://discourse.julialang.org/u/Luigi_Marongiu)\
**Replies:** 4\
**Last updated:** [April 5, 2022, 1:54pm UTC](https://discourse.julialang.org/t/how-to-create-data-frame-from-saved-vectors-in-julia-1-7/79046 "2022-04-05T13:54:58Z")

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Hello, I have a matrix features 2 columns 2000 rows and I would like to convert it into a data frame. I tried with: julia\> df = DataFrames(Time = features\[:,1\], Amount = features\[:,2\]) ERROR: MethodError: objects of t…

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## [How to load a dataset from another website using a the website link](https://discourse.julialang.org/t/how-to-load-a-dataset-from-another-website-using-a-the-website-link/79043)

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**Author:** [@habeebadeyemi](https://discourse.julialang.org/u/habeebadeyemi)\
**Replies:** 4\
**Last updated:** [April 5, 2022, 1:43pm UTC](https://discourse.julialang.org/t/how-to-load-a-dataset-from-another-website-using-a-the-website-link/79043 "2022-04-05T13:43:55Z")

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please help,i have a datasets on kaggle which needed to be load into my julia environment without downloading the dataset directly.

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## [Error in CUDA testing in VSCode](https://discourse.julialang.org/t/error-in-cuda-testing-in-vscode/79023)

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**Author:** [@ThePinkPanzer](https://discourse.julialang.org/u/ThePinkPanzer)\
**Replies:** 5\
**Last updated:** [April 5, 2022, 1:33pm UTC](https://discourse.julialang.org/t/error-in-cuda-testing-in-vscode/79023 "2022-04-05T13:33:45Z")

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I’ve been trying to set up CUDA.jl, and installed it using Pkg.add(“CUDA”). In the Julia command line it works, but in VSCode when I run the tests it throws up the following error: ERROR: LoadError: LoadError: could not…

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## [Why are there type-unstable matrix operations in \`Base\`?](https://discourse.julialang.org/t/why-are-there-type-unstable-matrix-operations-in-base/78999)

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**Author:** [@heliosdrm](https://discourse.julialang.org/u/heliosdrm)\
**Replies:** 6\
**Last updated:** [April 5, 2022, 12:06pm UTC](https://discourse.julialang.org/t/why-are-there-type-unstable-matrix-operations-in-base/78999 "2022-04-05T12:06:56Z")

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In other domains, type stability is given more priority than generalizability, e.g. for sqrt with numbers. But not for matrices: julia\> code\_warntype(sqrt, (Float64,)) # this is type-stable MethodInstance for sqrt(::Flo…

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## [Julia references at LLVM IR level](https://discourse.julialang.org/t/julia-references-at-llvm-ir-level/78870)

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**Author:** [@knlv.ok](https://discourse.julialang.org/u/knlv.ok)\
**Replies:** 1\
**Last updated:** [April 5, 2022, 12:05pm UTC](https://discourse.julialang.org/t/julia-references-at-llvm-ir-level/78870 "2022-04-05T12:05:31Z")

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Hello I’m coming to ask for your help today, because I have the following problem: As a toy example, I have implemented a multiplication function below: function mult!(res::Ref{Int16},a::Int16,b::Int16) res\[\]=a\*b …

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## [ORC file format](https://discourse.julialang.org/t/orc-file-format/79041)

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**Author:** [@Krzysztof\_Langner](https://discourse.julialang.org/u/Krzysztof_Langner)\
**Replies:** 1\
**Last updated:** [April 5, 2022, 11:49am UTC](https://discourse.julialang.org/t/orc-file-format/79041 "2022-04-05T11:49:56Z")

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Hello, Is there any package or code example to read ORC file format? https://orc.apache.org/specification/ORCv1/ Can’t find anything with google.

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## [Best way to cache data during DifferentialEquations.jl integration](https://discourse.julialang.org/t/best-way-to-cache-data-during-differentialequations-jl-integration/78996)

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**Author:** [@josuagrw](https://discourse.julialang.org/u/josuagrw)\
**Replies:** 1\
**Last updated:** [April 5, 2022, 11:44am UTC](https://discourse.julialang.org/t/best-way-to-cache-data-during-differentialequations-jl-integration/78996 "2022-04-05T11:44:35Z")

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I have a problem which could be written (not exactly) as \\dot u = \\min\_w f(u,w) Naturally, I would like use some previous value of \\dot u as the starting point for the optimization problem on the r.h.s. — I might even…

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## [Calculating Jacobian from two matrices](https://discourse.julialang.org/t/calculating-jacobian-from-two-matrices/78966)

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**Author:** [@Iddingsite](https://discourse.julialang.org/u/Iddingsite)\
**Replies:** 4\
**Last updated:** [April 5, 2022, 10:48am UTC](https://discourse.julialang.org/t/calculating-jacobian-from-two-matrices/78966 "2022-04-05T10:48:09Z")

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Hi everyone, I would like to compute a Jacobian for one of my problem for a PDE, but I don’t have a function linking the unknown to my function. So I only have 2 matrices, 1 with the values of the function and 1 with th…

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## [Ntlm authentication for HTTP requests](https://discourse.julialang.org/t/ntlm-authentication-for-http-requests/26488)

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**Author:** [@jonjilla](https://discourse.julialang.org/u/jonjilla)\
**Replies:** 2\
**Last updated:** [April 5, 2022, 9:47am UTC](https://discourse.julialang.org/t/ntlm-authentication-for-http-requests/26488 "2022-04-05T09:47:03Z")

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Hello I need to push some files into Sharepoint which requires NTLM authentication apparently. Does HTTP.jl support that type of authentication? I can’t find anything in the documentation about it one way or the other…

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## [Makie: layout question](https://discourse.julialang.org/t/makie-layout-question/79020)

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**Author:** [@vettert](https://discourse.julialang.org/u/vettert)\
**Replies:** 2\
**Last updated:** [April 5, 2022, 9:36am UTC](https://discourse.julialang.org/t/makie-layout-question/79020 "2022-04-05T09:36:41Z")

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I am having trouble adjusting the layout in my figure in Makie. Here is a screenshot of the figure that I manage to create: Now, I would really like to adjust the whitespace between the colorbar and my triangular con…

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## [\[ANN\] NeuronBuilder.jl: A differentiable neuronal simulator](https://discourse.julialang.org/t/ann-neuronbuilder-jl-a-differentiable-neuronal-simulator/78743)

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**Author:** [@AndreaRH](https://discourse.julialang.org/u/AndreaRH)\
**Replies:** 11\
**Last updated:** [April 5, 2022, 9:18am UTC](https://discourse.julialang.org/t/ann-neuronbuilder-jl-a-differentiable-neuronal-simulator/78743 "2022-04-05T09:18:25Z")

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NeuronBuilder.jl is a quick package for building small networks of detailed, conductance-based neurons out of ion channels and synapses. The idea is that it’s easy to use this template and add your own ion channels / syn…

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