# New to Julia

**URL:** https://discourse.julialang.org/c/first-steps/8.md?page=13

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**Page:** 14

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## [Concurrent Downloads.curl usage results in Error: curl\_multi\_socket\_action: 8](https://discourse.julialang.org/t/concurrent-downloads-curl-usage-results-in-error-curl-multi-socket-action-8/129860)

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**Author:** [@csvance](https://discourse.julialang.org/u/csvance)\
**Replies:** 0\
**Last updated:** [June 13, 2025, 12:54pm UTC](https://discourse.julialang.org/t/concurrent-downloads-curl-usage-results-in-error-curl-multi-socket-action-8/129860 "2025-06-13T12:54:33Z")

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Hi everyone, new to Julia and looking to integrate it into a SaMD as an alternative to Numba for performance critical sections of the code. As part of the performance critical sections, I’m trying to to use gRPC to call…

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## [Evaluate a local variable by name](https://discourse.julialang.org/t/evaluate-a-local-variable-by-name/129846)

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**Author:** [@goerz](https://discourse.julialang.org/u/goerz)\
**Replies:** 4\
**Last updated:** [June 13, 2025, 8:34am UTC](https://discourse.julialang.org/t/evaluate-a-local-variable-by-name/129846 "2025-06-13T08:34:40Z")

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Is there a particularly elegant way to eval a local variable? My use case would be this function: function A\_dipole(which, x, y, z; A₀=19.8517061694#=ų MHz=#) i, j = (Symbol(\_) for \_ in String(which)) r = √(x^2 + y^2…

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## [Timeout / early kill an external process](https://discourse.julialang.org/t/timeout-early-kill-an-external-process/53876)

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**Author:** [@s-baumann](https://discourse.julialang.org/u/s-baumann)\
**Replies:** 3\
**Last updated:** [June 12, 2025, 10:27pm UTC](https://discourse.julialang.org/t/timeout-early-kill-an-external-process/53876 "2025-06-12T22:27:19Z")

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I want to do a terminal command (on linux) with a timeout. I know there is not a timeout built into the run command so I was trying to do something to make one. So basically I tried: function run\_with\_timeout(command::S…

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## [How to replace backslash](https://discourse.julialang.org/t/how-to-replace-backslash/129816)

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**Author:** [@gvanuxem](https://discourse.julialang.org/u/gvanuxem)\
**Replies:** 2\
**Last updated:** [June 12, 2025, 10:01am UTC](https://discourse.julialang.org/t/how-to-replace-backslash/129816 "2025-06-12T10:01:51Z")

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Hello, For example, this one does not work: julia\> replace("foo \\spadbar{jjjd}","\\\\spad"=\>"") ERROR: ParseError: # Error @ REPL\[6\]:1:21 ulia\> replace("foo \\spadbar{jjjd}","\\\\spad"=\>"") # └┘ ── inval…

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## [Any recommended resources for using Julia in Computer Vision?](https://discourse.julialang.org/t/any-recommended-resources-for-using-julia-in-computer-vision/129812)

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**Author:** [@AI\_hayasaka](https://discourse.julialang.org/u/AI_hayasaka)\
**Replies:** 1\
**Last updated:** [June 12, 2025, 6:14am UTC](https://discourse.julialang.org/t/any-recommended-resources-for-using-julia-in-computer-vision/129812 "2025-06-12T06:14:23Z")

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I am looking for some good resources (books, videos, courses, etc…) for using Julia in computer vision domain. Especially with respect to, Object Detection, Image Classification, etc..

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## [Pkg.add("PyPlot" or Pkg.build("PyCall") not working](https://discourse.julialang.org/t/pkg-add-pyplot-or-pkg-build-pycall-not-working/129800)

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**Author:** [@Smara\_Kazenango](https://discourse.julialang.org/u/Smara_Kazenango)\
**Replies:** 14\
**Last updated:** [June 11, 2025, 7:22pm UTC](https://discourse.julialang.org/t/pkg-add-pyplot-or-pkg-build-pycall-not-working/129800 "2025-06-11T19:22:04Z")

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I have tried Pkg.add(“PyPlot”) or Pkg.build(“PyCall”) and both are not working and producing errors. Does anyone know how I can fix this to run my script?

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## [Reading model parameters and variables from excel](https://discourse.julialang.org/t/reading-model-parameters-and-variables-from-excel/129767)

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**Author:** [@Boris](https://discourse.julialang.org/u/Boris)\
**Replies:** 8\
**Last updated:** [June 10, 2025, 8:53pm UTC](https://discourse.julialang.org/t/reading-model-parameters-and-variables-from-excel/129767 "2025-06-10T20:53:32Z")

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Hello everyone! I have been migrating slowly some part of my work from Matlab to Julia and came across a more specific issue. Over the years I have automated some part of my matlab workflow using excel files for reading…

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## [GPU/CPU Agnostic FFT code](https://discourse.julialang.org/t/gpu-cpu-agnostic-fft-code/126283)

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**Author:** [@bpsomu](https://discourse.julialang.org/u/bpsomu)\
**Replies:** 7\
**Last updated:** [June 10, 2025, 10:21am UTC](https://discourse.julialang.org/t/gpu-cpu-agnostic-fft-code/126283 "2025-06-10T10:21:49Z")

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I am looking to port my Professor’s 15 year old C++ code to Julia in a GPU/CPU Agnostic way maybe by using AcceleratedKernels.jl. The C++ code uses FFTW library, I know CUDA has CUDAFFTs but I don’t know if AcceleratedKe…

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## [Compiling with @async](https://discourse.julialang.org/t/compiling-with-async/129726)

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**Author:** [@Doug719](https://discourse.julialang.org/u/Doug719)\
**Replies:** 1\
**Last updated:** [June 7, 2025, 6:25pm UTC](https://discourse.julialang.org/t/compiling-with-async/129726 "2025-06-07T18:25:36Z")

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If I enter t1 = @async begin; sleep(5); println("done1"); end at the julia REPL, I get Task (runnable, started) @0x00007f575a6c3d00 julia\> done1 If I compile and run function main() t1 = @async begin; sleep…

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## [Dot product abbreviation](https://discourse.julialang.org/t/dot-product-abbreviation/129719)

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**Author:** [@WalterMadelim](https://discourse.julialang.org/u/WalterMadelim)\
**Replies:** 4\
**Last updated:** [June 7, 2025, 3:43pm UTC](https://discourse.julialang.org/t/dot-product-abbreviation/129719 "2025-06-07T15:43:51Z")

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I wonder why these can’t be parsed. julia\> a, b = 2, 3; julia\> a'b 6 julia\> 2'b 6 julia\> a'3 ERROR: ParseError: # Error @ REPL\[5\]:1:3 a'3 # ╙ ── extra tokens after end of expression Stacktrace: \[1\] top-level scope …

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## [Julia version 1.11.4](https://discourse.julialang.org/t/julia-version-1-11-4/129689)

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**Author:** [@Smara\_Kazenango](https://discourse.julialang.org/u/Smara_Kazenango)\
**Replies:** 5\
**Last updated:** [June 7, 2025, 11:02am UTC](https://discourse.julialang.org/t/julia-version-1-11-4/129689 "2025-06-07T11:02:15Z")

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How can I use PyPlot, Images, Image IO and Flux.Data in Julia version 1.11.4. Running the Pkg.add(“PyPlot”) seems not to include all packages such as PyCall.

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## [Error after update](https://discourse.julialang.org/t/error-after-update/129700)

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**Author:** [@drarnau](https://discourse.julialang.org/u/drarnau)\
**Replies:** 8\
**Last updated:** [June 6, 2025, 1:20pm UTC](https://discourse.julialang.org/t/error-after-update/129700 "2025-06-06T13:20:53Z")

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I have an old project which uses Julia 1.7.1. I just did: \] activate . and: update Then: using MyPackage I get the following error: ERROR: LoadError: UndefVarError: pkgversion not defined Any ideas about what’s g…

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## [Is it possible to control space from axis to numbers and axis name?](https://discourse.julialang.org/t/is-it-possible-to-control-space-from-axis-to-numbers-and-axis-name/129678)

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**Author:** [@dankelley](https://discourse.julialang.org/u/dankelley)\
**Replies:** 6\
**Last updated:** [June 6, 2025, 1:11pm UTC](https://discourse.julialang.org/t/is-it-possible-to-control-space-from-axis-to-numbers-and-axis-name/129678 "2025-06-06T13:11:09Z")

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I come to julia from R. In R, my habit is to thin out the margins quite a lot, and snuggle the axis labels in very close to the data area. I know I can alter the margin span, but is there a way I can do this “snuggling…

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## [Questions about function inside struct](https://discourse.julialang.org/t/questions-about-function-inside-struct/129669)

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**Author:** [@Cyan](https://discourse.julialang.org/u/Cyan)\
**Replies:** 3\
**Last updated:** [June 5, 2025, 1:27pm UTC](https://discourse.julialang.org/t/questions-about-function-inside-struct/129669 "2025-06-05T13:27:55Z")

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Hi, all. I am new to Julia, is it possible to build a function in struct, and whether it is efficient in coding comparing with an independent function? struct s a function f(x,a) return a\*x …

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## [Package compatibility](https://discourse.julialang.org/t/package-compatibility/129653)

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**Author:** [@lancejnelson](https://discourse.julialang.org/u/lancejnelson)\
**Replies:** 9\
**Last updated:** [June 5, 2025, 7:01am UTC](https://discourse.julialang.org/t/package-compatibility/129653 "2025-06-05T07:01:38Z")

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I’m trying to install the ASE package and getting this error message: (@v1.11) pkg\> add ASE Resolving package versions... ERROR: Unsatisfiable requirements detected for package Dierckx \[39dd38d3\]: Dierckx \[39dd38d3\]…

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## [A plea from an old scientist for someone to write the Kernighan & Ritchie of Julia](https://discourse.julialang.org/t/a-plea-from-an-old-scientist-for-someone-to-write-the-kernighan-ritchie-of-julia/129332)

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**Author:** [@Darrel](https://discourse.julialang.org/u/Darrel)\
**Replies:** 7\
**Last updated:** [June 4, 2025, 12:01pm UTC](https://discourse.julialang.org/t/a-plea-from-an-old-scientist-for-someone-to-write-the-kernighan-ritchie-of-julia/129332 "2025-06-04T12:01:54Z")

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I don’t learn from videos. I read. Back in the Stone Age days of my undergrad, they first taught us Pascal and then PDP 11 assembly. I then worked in a lab programming PDP’s in assembly Since then I’ve programmed exten…

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## [Problem when add CairoMakie](https://discourse.julialang.org/t/problem-when-add-cairomakie/129616)

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**Author:** [@Cyan](https://discourse.julialang.org/u/Cyan)\
**Replies:** 3\
**Last updated:** [June 4, 2025, 6:44am UTC](https://discourse.julialang.org/t/problem-when-add-cairomakie/129616 "2025-06-04T06:44:40Z")

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When I tried to add CairoMakie, I got this warning: Warning: downloading texture atlas failed, need to re-create from scratch. │ │ exception = │ │ RequestError: HTTP/2 302 (Failed to connect to objects.githubuser…

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## [Syntax about \*(a, b)](https://discourse.julialang.org/t/syntax-about-a-b/129546)

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**Author:** [@WalterMadelim](https://discourse.julialang.org/u/WalterMadelim)\
**Replies:** 19\
**Last updated:** [June 3, 2025, 10:36am UTC](https://discourse.julialang.org/t/syntax-about-a-b/129546 "2025-06-03T10:36:43Z")

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I think it is reasonable for users to write code in the latter style, but it errors, can this be improved? julia\> \[2\*3 3\*4; 3\*4 2\*3\] 2×2 Matrix{Int64}: 6 12 12 6 julia\> \[\*(2, 3) \*(3, 4); \*(3, 4) \*(2…

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## [Precision issues in exponent computation and differential equation](https://discourse.julialang.org/t/precision-issues-in-exponent-computation-and-differential-equation/129591)

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**Author:** [@Sahil\_Khan](https://discourse.julialang.org/u/Sahil_Khan)\
**Replies:** 2\
**Last updated:** [June 3, 2025, 9:30am UTC](https://discourse.julialang.org/t/precision-issues-in-exponent-computation-and-differential-equation/129591 "2025-06-03T09:30:25Z")

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Hello, Im working on a differential equation based model some of its equations has power term (x^a) which is major issue because without this model works fine. Now issue is that I have used stiff solver(RodasP5), differ…

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## [Parameter estimation for Fractional differential equations](https://discourse.julialang.org/t/parameter-estimation-for-fractional-differential-equations/129549)

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**Author:** [@SANYAM\_TYAGI](https://discourse.julialang.org/u/SANYAM_TYAGI)\
**Replies:** 2\
**Last updated:** [June 3, 2025, 5:33am UTC](https://discourse.julialang.org/t/parameter-estimation-for-fractional-differential-equations/129549 "2025-06-03T05:33:19Z")

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Hi, I am a new to Julia. I have been trying to fit my FDE model to a data set. I was trying to do it in MATLAB but there are no stiff solvers for fractional differential equations (not in my knowledge). Everything seems …

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## [MTK Control System with Current Not Working](https://discourse.julialang.org/t/mtk-control-system-with-current-not-working/129558)

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**Author:** [@madtorresga](https://discourse.julialang.org/u/madtorresga)\
**Replies:** 1\
**Last updated:** [June 2, 2025, 1:17pm UTC](https://discourse.julialang.org/t/mtk-control-system-with-current-not-working/129558 "2025-06-02T13:17:26Z")

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Hello! I’m trying to implement this exact same example, but controlling with the current that passes through the resistance instead of the speed in speed\_sensor.w. @equations begin #... #connect(curre…

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## [Allocations when moving loop into a function](https://discourse.julialang.org/t/allocations-when-moving-loop-into-a-function/129534)

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**Author:** [@omicron8](https://discourse.julialang.org/u/omicron8)\
**Replies:** 3\
**Last updated:** [June 1, 2025, 10:04pm UTC](https://discourse.julialang.org/t/allocations-when-moving-loop-into-a-function/129534 "2025-06-01T22:04:08Z")

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Why does the first variant (function foo) allocate a large amount of memory while the second variant (function bar) does not? The difference is whether the loop is inside or outside the function. Is there a way to have t…

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

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**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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## [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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## [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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## [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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## [Get an eigvec by eigval, using eigvecs, only allow SymTridiagonal?](https://discourse.julialang.org/t/get-an-eigvec-by-eigval-using-eigvecs-only-allow-symtridiagonal/127408)

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**Author:** [@WalterMadelim](https://discourse.julialang.org/u/WalterMadelim)\
**Replies:** 12\
**Last updated:** [May 29, 2025, 10:40pm UTC](https://discourse.julialang.org/t/get-an-eigvec-by-eigval-using-eigvecs-only-allow-symtridiagonal/127408 "2025-05-29T22:40:55Z")

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Hi, there I wonder why the eigvecs method does not work for a A::Symmetric{Int64, Matrix{Int64}}. using LinearAlgebra A = SymTridiagonal(\[1.; 2.; 1.\], \[2.; 3.\]) val3 = eigvals(A)\[3\] vec3 = reshape(eigvecs(A, \[val3\]), (…

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## [How to point Julia to a python executable](https://discourse.julialang.org/t/how-to-point-julia-to-a-python-executable/129388)

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**Author:** [@keynescoefen](https://discourse.julialang.org/u/keynescoefen)\
**Replies:** 9\
**Last updated:** [May 29, 2025, 10:30pm UTC](https://discourse.julialang.org/t/how-to-point-julia-to-a-python-executable/129388 "2025-05-29T22:30:34Z")

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Hello, When trying to precompile PythonCall I received the following error IOError: could not spawn \`/Users/jerome/.julia/environments/v1.11/.CondaPkg/.pixi/envs/default/bin/python --version\`: no such file or directory …

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## [Solving ODE on GPU from Python with DifferentialEquations.jl](https://discourse.julialang.org/t/solving-ode-on-gpu-from-python-with-differentialequations-jl/109999)

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**Author:** [@SantiagoMorandi](https://discourse.julialang.org/u/SantiagoMorandi)\
**Replies:** 11\
**Last updated:** [May 29, 2025, 12:02am UTC](https://discourse.julialang.org/t/solving-ode-on-gpu-from-python-with-differentialequations-jl/109999 "2025-05-29T00:02:13Z")

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Hi everyone, I am new in Julia. My goal is to solve stiff ODE systems (N\>1000) representing chemical reaction networks up to steady-state conditions. Since the Python Scipy implementation is too slow for the purpose, I…

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## [Sudden slowdown with ODEProblem](https://discourse.julialang.org/t/sudden-slowdown-with-odeproblem/128909)

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**Author:** [@rswhittle](https://discourse.julialang.org/u/rswhittle)\
**Replies:** 10\
**Last updated:** [May 28, 2025, 1:03am UTC](https://discourse.julialang.org/t/sudden-slowdown-with-odeproblem/128909 "2025-05-28T01:03:07Z")

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Hi, throwing out a Hail Mary here as I have no idea what I am doing. We had/have a working ModelingToolkit model, then suddenly last night it stopped working as the DifferentialEquations.jl package wouldn’t precompile (…

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