# Latest

**URL:** https://discourse.julialang.org/latest.md?page=157

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

**Page:** 158

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## [How to target Intel performance cores only in multithreading](https://discourse.julialang.org/t/how-to-target-intel-performance-cores-only-in-multithreading/91415)

<div class="topic-metadata">

**Author:** [@babakfifoo](https://discourse.julialang.org/u/babakfifoo)\
**Replies:** 5\
**Last updated:** [June 1, 2025, 10:42am UTC](https://discourse.julialang.org/t/how-to-target-intel-performance-cores-only-in-multithreading/91415 "2025-06-01T10:42:07Z")

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Hi all, I have a code that uses multithreading. My system has 12700K with 6/2 performance cores and 8 efficiency cores The issue I have is that I want to use only performance cores since efficiency cores are not strong…

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## [Surprising test timings](https://discourse.julialang.org/t/surprising-test-timings/129437)

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**Author:** [@TimG](https://discourse.julialang.org/u/TimG)\
**Replies:** 4\
**Last updated:** [June 1, 2025, 7:06am UTC](https://discourse.julialang.org/t/surprising-test-timings/129437 "2025-06-01T07:06:31Z")

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When I run tests on a package I’ve been working on, the output shows (for a subset of tests): Test Summary: | Pass Total Time Styles | 775 775 49.0s Test Summary: | Pass Total Time Conditional For…

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## [DuckDB Array Not Supported?](https://discourse.julialang.org/t/duckdb-array-not-supported/129508)

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**Author:** [@NAS](https://discourse.julialang.org/u/NAS)\
**Replies:** 3\
**Last updated:** [June 1, 2025, 5:28am UTC](https://discourse.julialang.org/t/duckdb-array-not-supported/129508 "2025-06-01T05:28:01Z")

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I was able to use the DuckDB Appender API to insert data into a table in the form of: CREATE OR REPLACE TABLE embeds (id INTEGER PRIMARY KEY, acc STRING, esm\_embed NUMERIC(9,8)\[1280\]) where the esm\_embed column is a ve…

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## [No win situations for me no matter what I post here](https://discourse.julialang.org/t/no-win-situations-for-me-no-matter-what-i-post-here/129506)

<div class="topic-metadata">

**Author:** [@Tarny\_GG\_Channie](https://discourse.julialang.org/u/Tarny_GG_Channie)\
**Replies:** 8\
**Last updated:** [June 1, 2025, 3:53am UTC](https://discourse.julialang.org/t/no-win-situations-for-me-no-matter-what-i-post-here/129506 "2025-06-01T03:53:17Z")

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It seems like I have a no-win situation. No matter what I post here, the engagement is either nonexistent, pointless or not very positive. High ambitions: There are threads where I try to suggest some theoretical Julia …

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## [My idea on a Julia game engine with MLIR](https://discourse.julialang.org/t/my-idea-on-a-julia-game-engine-with-mlir/129490)

<div class="topic-metadata">

**Author:** [@Tarny\_GG\_Channie](https://discourse.julialang.org/u/Tarny_GG_Channie)\
**Replies:** 11\
**Last updated:** [June 1, 2025, 2:34am UTC](https://discourse.julialang.org/t/my-idea-on-a-julia-game-engine-with-mlir/129490 "2025-06-01T02:34:50Z")

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Here’s an idea. What if we can make a game engine that beats Unity, Unreal, Godot, Bevy, etc, and also an asset editor that beats Blender, Maya, Houdini, etc? Not that I can do it right now, but perhaps in theory. It’s…

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## [Using DuckDB appender with JSON column](https://discourse.julialang.org/t/using-duckdb-appender-with-json-column/129283)

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**Author:** [@slwu89](https://discourse.julialang.org/u/slwu89)\
**Replies:** 5\
**Last updated:** [May 31, 2025, 9:10pm UTC](https://discourse.julialang.org/t/using-duckdb-appender-with-json-column/129283 "2025-05-31T21:10:39Z")

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Hi all, I’m interested to know if it would be possible to adjust the Appender API in DuckDB to support JSON. Let me explain. As noted here JSON Overview – DuckDB we can create columns with the JSON data type. However, i…

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## [\[ANN\] New package WinchControllers](https://discourse.julialang.org/t/ann-new-package-winchcontrollers/129507)

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**Author:** [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Replies:** 0\
**Last updated:** [May 31, 2025, 7:18pm UTC](https://discourse.julialang.org/t/ann-new-package-winchcontrollers/129507 "2025-05-31T19:18:56Z")

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Recently, we registered the package WinchControllers.jl, and the new release 0.5.3 is ready for practical use. While it was developed for airborne wind energy systems, it should be useful everywhere where winches are ne…

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## [Why is \`\[\["x", "y"\], \[1\]\]\` a \`Vector{Vector}\`?](https://discourse.julialang.org/t/why-is-x-y-1-a-vector-vector/129318)

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**Author:** [@enweg](https://discourse.julialang.org/u/enweg)\
**Replies:** 10\
**Last updated:** [May 31, 2025, 6:43pm UTC](https://discourse.julialang.org/t/why-is-x-y-1-a-vector-vector/129318 "2025-05-31T18:43:21Z")

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I am trying to write a function similar to the following, where I want y to be a Vector of Vectors where each inner vector is either Vector{String} or Vector{Int}. foo(x::SomeType, y) I am unsure about which type to us…

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## [Very long time for addition of complex identity matrix to transposed sparse matrix](https://discourse.julialang.org/t/very-long-time-for-addition-of-complex-identity-matrix-to-transposed-sparse-matrix/129465)

<div class="topic-metadata">

**Author:** [@rveltz](https://discourse.julialang.org/u/rveltz)\
**Replies:** 10\
**Last updated:** [May 31, 2025, 5:20pm UTC](https://discourse.julialang.org/t/very-long-time-for-addition-of-complex-identity-matrix-to-transposed-sparse-matrix/129465 "2025-05-31T17:20:12Z")

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Hi, I am surprised by these timings on 1.10. Can it be improved? using SparseArrays, LinearAlgebra A = sprandn(90000,90000, 1e-5) @time (A + complex(0,1.) \* I); # 0.001344 seconds (13 allocations: 7.342 MiB) @time (tr…

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## [Nonlinear boundary conditions in ApproxFun](https://discourse.julialang.org/t/nonlinear-boundary-conditions-in-approxfun/129504)

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**Author:** [@MingjiaYan](https://discourse.julialang.org/u/MingjiaYan)\
**Replies:** 0\
**Last updated:** [May 31, 2025, 3:43pm UTC](https://discourse.julialang.org/t/nonlinear-boundary-conditions-in-approxfun/129504 "2025-05-31T15:43:07Z")

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Hi, I’m trying to solve for the steady state solution of a one-dimensional heat equation describing a nonlinear heat conduction in a finite domain \[0,1\] using ApproxFun.jl: T\_{xx} = 0 subject to a Dirichlet boundary c…

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## [Reducing allocations](https://discourse.julialang.org/t/reducing-allocations/129415)

<div class="topic-metadata">

**Author:** [@lancejnelson](https://discourse.julialang.org/u/lancejnelson)\
**Replies:** 44\
**Last updated:** [May 31, 2025, 3:12pm UTC](https://discourse.julialang.org/t/reducing-allocations/129415 "2025-05-31T15:12:26Z")

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I have a function that is going to be called many hundreds of thousands of times so I want it optimized maximally. To reduce allocations, I decided I would create a struct the stored some buffer arrays, then I would ass…

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## [Using AI programming problem solvers to help develop Julia Linear Algebra ecosystem](https://discourse.julialang.org/t/using-ai-programming-problem-solvers-to-help-develop-julia-linear-algebra-ecosystem/129501)

<div class="topic-metadata">

**Author:** [@Tarny\_GG\_Channie](https://discourse.julialang.org/u/Tarny_GG_Channie)\
**Replies:** 2\
**Last updated:** [May 31, 2025, 12:53pm UTC](https://discourse.julialang.org/t/using-ai-programming-problem-solvers-to-help-develop-julia-linear-algebra-ecosystem/129501 "2025-05-31T12:53:43Z")

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We’ve had yet another instance of slow matrix operation due to generic fallback. This is not the only one for example. Guess what? We have a set of self-contained problems with known ground truth (implemented by the…

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## [Reliably make a clean copy of an XML node](https://discourse.julialang.org/t/reliably-make-a-clean-copy-of-an-xml-node/129495)

<div class="topic-metadata">

**Author:** [@TimG](https://discourse.julialang.org/u/TimG)\
**Replies:** 4\
**Last updated:** [May 31, 2025, 12:17pm UTC](https://discourse.julialang.org/t/reliably-make-a-clean-copy-of-an-xml-node/129495 "2025-05-31T12:17:51Z")

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I am using XML.jl. I have a basic XML node that I use as a base from which I wish to construct many slightly different instances. On each occasion, I want to copy the basic node and build from there. The Readme page for…

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## [2D-FFT gives nonzero imaginary value at \[1,1\]](https://discourse.julialang.org/t/2d-fft-gives-nonzero-imaginary-value-at-1-1/129500)

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**Author:** [@heliosdrm](https://discourse.julialang.org/u/heliosdrm)\
**Replies:** 1\
**Last updated:** [May 31, 2025, 11:08am UTC](https://discourse.julialang.org/t/2d-fft-gives-nonzero-imaginary-value-at-1-1/129500 "2025-05-31T11:08:12Z")

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Perhaps this is just my imperfect knowledge of how FFT works, but according to the theory, the Fourier transform at zero frequency of real-valued data is always real, and I thought that this should also happen with FFT. …

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## [\`check-bounds=no\` causes illegal memory access when using \`rand()\` in CUDA kernel](https://discourse.julialang.org/t/check-bounds-no-causes-illegal-memory-access-when-using-rand-in-cuda-kernel/129455)

<div class="topic-metadata">

**Author:** [@0samuraiE](https://discourse.julialang.org/u/0samuraiE)\
**Replies:** 3\
**Last updated:** [May 31, 2025, 7:38am UTC](https://discourse.julialang.org/t/check-bounds-no-causes-illegal-memory-access-when-using-rand-in-cuda-kernel/129455 "2025-05-31T07:38:44Z")

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I’m encountering an error when running the following minimal example with check-bounds=no. With bounds checking enabled (check-bounds=yes), it works fine. But disabling it causes: ERROR: CUDA error: an illegal memory ac…

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## [Mapping Dream Patterns with Julia & Makie – A Symbolic Matrix Model](https://discourse.julialang.org/t/mapping-dream-patterns-with-julia-makie-a-symbolic-matrix-model/129489)

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**Author:** [@Otkatilo](https://discourse.julialang.org/u/Otkatilo)\
**Replies:** 3\
**Last updated:** [May 31, 2025, 5:33am UTC](https://discourse.julialang.org/t/mapping-dream-patterns-with-julia-makie-a-symbolic-matrix-model/129489 "2025-05-31T05:33:07Z")

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Hi Julia community! This is my first post here, and I’m excited to begin my journey with the Julia programming language. I’m currently working on a personal hobby project focused on visualization. Until now, I’ve been u…

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## [\[ANN\] ExchangeRates.jl](https://discourse.julialang.org/t/ann-exchangerates-jl/129317)

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**Author:** [@tp2750](https://discourse.julialang.org/u/tp2750)\
**Replies:** 10\
**Last updated:** [May 31, 2025, 5:27am UTC](https://discourse.julialang.org/t/ann-exchangerates-jl/129317 "2025-05-31T05:27:22Z")

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I often need to convert prices in webshops to my local currency to better understand it. This small package ExchangeRates.jl does this with a (in my opinion) slick interface: julia\> using ExchangeRates \[ Info: Fetching…

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## [How to build a wrapper around a C-style array using Julia C API?](https://discourse.julialang.org/t/how-to-build-a-wrapper-around-a-c-style-array-using-julia-c-api/129469)

<div class="topic-metadata">

**Author:** [@dmitry-kabanov](https://discourse.julialang.org/u/dmitry-kabanov)\
**Replies:** 4\
**Last updated:** [May 31, 2025, 12:55am UTC](https://discourse.julialang.org/t/how-to-build-a-wrapper-around-a-c-style-array-using-julia-c-api/129469 "2025-05-31T00:55:11Z")

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Hi, I need to use the Julia C API to build a wrapper around a C-style array to use this array in Julia (the array is actually a Python NumPy array). The thing is that the array is a matrix (2D) and Julia uses Fortran-sty…

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## [Is it possible to create a closed source library package?](https://discourse.julialang.org/t/is-it-possible-to-create-a-closed-source-library-package/129453)

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**Author:** [@victor\_vhrn](https://discourse.julialang.org/u/victor_vhrn)\
**Replies:** 2\
**Last updated:** [May 31, 2025, 1:20am UTC](https://discourse.julialang.org/t/is-it-possible-to-create-a-closed-source-library-package/129453 "2025-05-31T01:20:32Z")

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Is it possible to release a package without easily exposing the source code? In my use case, my package is a library where the user must provide callback functions as input. Most of the ideas I found seem to apply only t…

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## [Batched matrix-multiplication optimization](https://discourse.julialang.org/t/batched-matrix-multiplication-optimization/129454)

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**Author:** [@quantumdreamer](https://discourse.julialang.org/u/quantumdreamer)\
**Replies:** 15\
**Last updated:** [May 30, 2025, 10:52pm UTC](https://discourse.julialang.org/t/batched-matrix-multiplication-optimization/129454 "2025-05-30T22:52:55Z")

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How can matrix multiplication in a for loop be optimized? Here is an example of mine: original case: Z = Array{ComplexF64,3}(undef,512,8,24192); X = Array{ComplexF64,3}(undef,512,16,24192); Y = Array{ComplexF64,3}(unde…

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## [PhD position in generative models of proteins at Karolinska (Stockholm)](https://discourse.julialang.org/t/phd-position-in-generative-models-of-proteins-at-karolinska-stockholm/129486)

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**Author:** [@Noob](https://discourse.julialang.org/u/Noob)\
**Replies:** 1\
**Last updated:** [May 30, 2025, 9:55pm UTC](https://discourse.julialang.org/t/phd-position-in-generative-models-of-proteins-at-karolinska-stockholm/129486 "2025-05-30T21:55:52Z")

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tl;dr: A computational PhD position (expected to be 100% in Julia) in generative models of proteins at Karolinska, Stockholm: Deadline: 2025-06-15 My lab at Karolinska (in Stockholm, Sweden) is looking for someone wit…

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## [Current state of Metal.jl for ML and SciML](https://discourse.julialang.org/t/current-state-of-metal-jl-for-ml-and-sciml/129476)

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**Author:** [@Bizzi](https://discourse.julialang.org/u/Bizzi)\
**Replies:** 2\
**Last updated:** [May 30, 2025, 7:59pm UTC](https://discourse.julialang.org/t/current-state-of-metal-jl-for-ml-and-sciml/129476 "2025-05-30T19:59:28Z")

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How feasible is using Apple Metal and Metal.jl for machine learning work? Metal.jl’s README says The package is a work-in-progress. There are bugs, functionality is missing, and performance hasn’t been optimized. Expec…

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## [Documenter "undefined binding" error](https://discourse.julialang.org/t/documenter-undefined-binding-error/129475)

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**Author:** [@Marco-Congedo](https://discourse.julialang.org/u/Marco-Congedo)\
**Replies:** 2\
**Last updated:** [May 30, 2025, 6:03pm UTC](https://discourse.julialang.org/t/documenter-undefined-binding-error/129475 "2025-05-30T18:03:04Z")

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I implemented a new function sumOfSqrDiff in package PosDefManifold.jl. I have exported it and added the doc string, but when i build the documentation i have the error here below. I don’t see what’s wrong and the sol…

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## [Dual\_ftol\_rel keyword not allowed in Optimization.jl](https://discourse.julialang.org/t/dual-ftol-rel-keyword-not-allowed-in-optimization-jl/129480)

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**Author:** [@miguelborrero](https://discourse.julialang.org/u/miguelborrero)\
**Replies:** 1\
**Last updated:** [May 30, 2025, 5:58pm UTC](https://discourse.julialang.org/t/dual-ftol-rel-keyword-not-allowed-in-optimization-jl/129480 "2025-05-30T17:58:29Z")

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Hi there, I’m trying out different solvers for my problem which requires evaluation of non-linear constraints. Currently I’m trying NLopt thought Optimization in particular LD\_CCSAQ solver. However, its taking forever a…

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## [Post-doctoral positions (UNICAMP - Campinas, Brazil)](https://discourse.julialang.org/t/post-doctoral-positions-unicamp-campinas-brazil/129482)

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**Author:** [@lmiq](https://discourse.julialang.org/u/lmiq)\
**Replies:** 0\
**Last updated:** [May 30, 2025, 5:22pm UTC](https://discourse.julialang.org/t/post-doctoral-positions-unicamp-campinas-brazil/129482 "2025-05-30T17:22:50Z")

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CCES Post-doctoral position call 2025 Registration form: https://forms.gle/Tc8bGPRzJiEKz5rM7 The Center for Computing in Engineering and Sciences (CCES) at UNICAMP is seeking to fill 4 postdoctoral positions in the are…

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## [Performance of applying a struct as a function](https://discourse.julialang.org/t/performance-of-applying-a-struct-as-a-function/129434)

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**Author:** [@JADekker](https://discourse.julialang.org/u/JADekker)\
**Replies:** 15\
**Last updated:** [May 30, 2025, 3:17pm UTC](https://discourse.julialang.org/t/performance-of-applying-a-struct-as-a-function/129434 "2025-05-30T15:17:23Z")

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I’m not sure what the exact name of this phenomenon is, so I’ll change the title if necessary, but my question involves the following situation: I have some structs that determine how certain data x is transformed: abst…

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## [Transient Stokes - Mass Matrix DAE - Dirichlet Boundary Conditions - Jacobian](https://discourse.julialang.org/t/transient-stokes-mass-matrix-dae-dirichlet-boundary-conditions-jacobian/129459)

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**Author:** [@ziolai](https://discourse.julialang.org/u/ziolai)\
**Replies:** 1\
**Last updated:** [May 30, 2025, 1:24pm UTC](https://discourse.julialang.org/t/transient-stokes-mass-matrix-dae-dirichlet-boundary-conditions-jacobian/129459 "2025-05-30T13:24:44Z")

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I am attempting to solve transient Stokes flow in a canonical channel (parabolic inlet, no-slip bottom and top wall, fixed pressure and inlet). The Stokes problem leads to a mass-matrix DAE. A naive hand code backward E…

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## [Interpolation in Modeling Toolkit](https://discourse.julialang.org/t/interpolation-in-modeling-toolkit/128094)

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**Author:** [@JaviJR](https://discourse.julialang.org/u/JaviJR)\
**Replies:** 3\
**Last updated:** [May 30, 2025, 12:15pm UTC](https://discourse.julialang.org/t/interpolation-in-modeling-toolkit/128094 "2025-05-30T12:15:14Z")

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Hello everyone, I’m gradually getting into the Julia ecosystem and I find it fascinating. I’m experimenting with developing models using ModelingToolkit.jl and I’ve come across a challenge that I haven’t been able to so…

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## [Last day to submit to JuliaCon Local Paris 2025!](https://discourse.julialang.org/t/last-day-to-submit-to-juliacon-local-paris-2025/129473)

<div class="topic-metadata">

**Author:** [@gdalle](https://discourse.julialang.org/u/gdalle)\
**Replies:** 0\
**Last updated:** [May 30, 2025, 12:09pm UTC](https://discourse.julialang.org/t/last-day-to-submit-to-juliacon-local-paris-2025/129473 "2025-05-30T12:09:05Z")

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Hi everyone! The call for proposals of JuliaCon Local Paris 2025 closes in just about a day (May 30th, anywhere on earth). Last chance to submit your awesome talk or cool package poster :timer\_clock: Links: Conferenc…

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## [Checking that a position is inside a AREA works in EPSG:25382 projection, but not in CRS84](https://discourse.julialang.org/t/checking-that-a-position-is-inside-a-area-works-in-epsg-25382-projection-but-not-in-crs84/129471)

<div class="topic-metadata">

**Author:** [@sfuerst](https://discourse.julialang.org/u/sfuerst)\
**Replies:** 1\
**Last updated:** [May 30, 2025, 11:52am UTC](https://discourse.julialang.org/t/checking-that-a-position-is-inside-a-area-works-in-epsg-25382-projection-but-not-in-crs84/129471 "2025-05-30T11:52:00Z")

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I have first to say, that I’m a newbie when it comes to geo-related stuff, so please excuse me if I ask or formulate something stupid here, but I’ve been biting my teeth out on this problem for hours. First a little con…

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