# Latest

**URL:** https://discourse.julialang.org/latest.md?page=150

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

**Page:** 151

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## [JuMP.NormOneCone()](https://discourse.julialang.org/t/jump-normonecone/129768)

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**Author:** [@WalterMadelim](https://discourse.julialang.org/u/WalterMadelim)\
**Replies:** 13\
**Last updated:** [June 15, 2025, 10:47pm UTC](https://discourse.julialang.org/t/jump-normonecone/129768 "2025-06-15T22:47:45Z")

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Can this NormOneCone be made easier? as SecondOrderCone is? It will find it use in linear programming. In my code, I now write something like nm1e = JuMP.@variable(outer) nm1c = JuMP.@constraint(outer, \[nm1e; vec(out…

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## [Block matrix linear solve performance](https://discourse.julialang.org/t/block-matrix-linear-solve-performance/129353)

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**Author:** [@Karajan](https://discourse.julialang.org/u/Karajan)\
**Replies:** 6\
**Last updated:** [June 15, 2025, 5:41pm UTC](https://discourse.julialang.org/t/block-matrix-linear-solve-performance/129353 "2025-06-15T17:41:51Z")

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Hi there! I have located a bottleneck in my simulations I could use some help with. I think this is mainly a linear algebra problem rather than pure Julia performance, but I know very little about that field so I’m not …

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## [How to use NumPy slices in 2d for PyPlot's GridSpec](https://discourse.julialang.org/t/how-to-use-numpy-slices-in-2d-for-pyplots-gridspec/40023)

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**Author:** [@roi.holtzman](https://discourse.julialang.org/u/roi.holtzman)\
**Replies:** 3\
**Last updated:** [June 15, 2025, 1:06pm UTC](https://discourse.julialang.org/t/how-to-use-numpy-slices-in-2d-for-pyplots-gridspec/40023 "2025-06-15T13:06:52Z")

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I am trying to create a plot with multiple subplots in PyPlot. For that I am using matplotlib’s GridSpec . Some of the usage is given by NumPy slices as seen in their example from the docs: fig8 = plt.figure(constraine…

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## [Yet another language benchmark](https://discourse.julialang.org/t/yet-another-language-benchmark/127924)

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**Author:** [@juliohm](https://discourse.julialang.org/u/juliohm)\
**Replies:** 9\
**Last updated:** [June 15, 2025, 12:13pm UTC](https://discourse.julialang.org/t/yet-another-language-benchmark/127924 "2025-06-15T12:13:00Z")

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I like the visuals in this one. As usual, Julia compilation seems to be included in the results: P.S.: we don’t have a HPC category on discourse. Should it be created? The GPU and Julia at Scale categories could be su…

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## [Read!( ) not working for HDF5 file](https://discourse.julialang.org/t/read-not-working-for-hdf5-file/129722)

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**Author:** [@raman\_kumar](https://discourse.julialang.org/u/raman_kumar)\
**Replies:** 1\
**Last updated:** [June 15, 2025, 11:46am UTC](https://discourse.julialang.org/t/read-not-working-for-hdf5-file/129722 "2025-06-15T11:46:24Z")

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I have an HDF5 file. I want to read or allocate its data in variable r repeatedly instead of allocating in different places :seat: in memory. using HDF5 fname = tempname(); # temporary file fid = h5open(fname, "w") cre…

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## [SymbolicRegression stuck at version 0.22.2](https://discourse.julialang.org/t/symbolicregression-stuck-at-version-0-22-2/129823)

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**Author:** [@Sam\_P](https://discourse.julialang.org/u/Sam_P)\
**Replies:** 6\
**Last updated:** [June 15, 2025, 5:23am UTC](https://discourse.julialang.org/t/symbolicregression-stuck-at-version-0-22-2/129823 "2025-06-15T05:23:05Z")

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Hi all. Just playing around with SymbolicRegression.jl and notice the version kept getting stuck on v0.22.2 instead of the latest v1.11.1. And when I force install that version, the ForwardDiff.jl went from 1.0.1 down to…

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## [Pretty print summary statistics for a dataframe](https://discourse.julialang.org/t/pretty-print-summary-statistics-for-a-dataframe/129838)

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**Author:** [@theabhirath](https://discourse.julialang.org/u/theabhirath)\
**Replies:** 4\
**Last updated:** [June 15, 2025, 2:27am UTC](https://discourse.julialang.org/t/pretty-print-summary-statistics-for-a-dataframe/129838 "2025-06-15T02:27:29Z")

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I’m looking to print out a summary of missing values in each row and column for a dataframe, but ideally I want to print it alongside the actual dataframe itself – in my head it looks something like this (pardon the crud…

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## [Looking for DiffEQArrayOperator replacement](https://discourse.julialang.org/t/looking-for-diffeqarrayoperator-replacement/128494)

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**Author:** [@cardoza2](https://discourse.julialang.org/u/cardoza2)\
**Replies:** 2\
**Last updated:** [June 14, 2025, 7:54pm UTC](https://discourse.julialang.org/t/looking-for-diffeqarrayoperator-replacement/128494 "2025-06-14T19:54:00Z")

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Hi, I got asked to maintain a package that someone else in my research group developed, so I apologize if this question is off topic. The package I’m working on uses SciMLBase v1, but I’m looking to update to v2. Previ…

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## [How is \`Symbol\` special?](https://discourse.julialang.org/t/how-is-symbol-special/129885)

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**Author:** [@nsajko](https://discourse.julialang.org/u/nsajko)\
**Replies:** 8\
**Last updated:** [June 14, 2025, 4:18pm UTC](https://discourse.julialang.org/t/how-is-symbol-special/129885 "2025-06-14T16:18:02Z")

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Symbol is a mutable struct, just like Expr: julia\> dump(Expr) mutable struct Expr \<: Any head::Symbol args::Vector{Any} julia\> dump(Symbol) mutable struct Symbol \<: Any Although it’s not possible to mutate it, as…

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## [Weird behavior of GraphNeuralNetworks.jl \`SGConv\` layer within \`Flux.withgradient\`](https://discourse.julialang.org/t/weird-behavior-of-graphneuralnetworks-jl-sgconv-layer-within-flux-withgradient/129701)

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**Author:** [@MackHarry](https://discourse.julialang.org/u/MackHarry)\
**Replies:** 5\
**Last updated:** [June 14, 2025, 4:34pm UTC](https://discourse.julialang.org/t/weird-behavior-of-graphneuralnetworks-jl-sgconv-layer-within-flux-withgradient/129701 "2025-06-14T16:34:32Z")

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First, I am quite new to Julia’s ML ecosystem, so I might have made stupid mistakes.. Recently, I tried to debug a very training loop involving GraphNeuralNetworks.jl’s SGConv layer, and found successively longer runti…

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## [Why is \`Expr\` mutable?](https://discourse.julialang.org/t/why-is-expr-mutable/129850)

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**Author:** [@PatrickHaecker](https://discourse.julialang.org/u/PatrickHaecker)\
**Replies:** 9\
**Last updated:** [June 14, 2025, 11:32am UTC](https://discourse.julialang.org/t/why-is-expr-mutable/129850 "2025-06-14T11:32:34Z")

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Expr does not have object identity have field equality, i.e. julia\> Expr(:call, println) == Expr(:call, println) true I was surprised to learn that Expr nevertheless is mutable. I can easily imagine why Expr does not h…

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## [Dispatch on keywords](https://discourse.julialang.org/t/dispatch-on-keywords/129854)

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**Author:** [@Cyan](https://discourse.julialang.org/u/Cyan)\
**Replies:** 6\
**Last updated:** [June 14, 2025, 8:34am UTC](https://discourse.julialang.org/t/dispatch-on-keywords/129854 "2025-06-14T08:34:01Z")

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I wrote these two functions function test(;e::Float64) return e^2 end function test(;e::Int) return e\*2 end I obtain the right answer when test(1.) or test(1), but the test(e=1.) returns an error of: TypeErro…

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## [Problems about using modules in same file](https://discourse.julialang.org/t/problems-about-using-modules-in-same-file/129865)

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**Author:** [@Cyan](https://discourse.julialang.org/u/Cyan)\
**Replies:** 4\
**Last updated:** [June 14, 2025, 4:10am UTC](https://discourse.julialang.org/t/problems-about-using-modules-in-same-file/129865 "2025-06-14T04:10:57Z")

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I tried code like this module moduleA function f1() println("test") end end module moduleB function f2() moduleA.f1() end end moduleB.f2() but it turned out ERROR: UndefVarError: \`mod…

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## [Disable extra information when using @warn](https://discourse.julialang.org/t/disable-extra-information-when-using-warn/129826)

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**Author:** [@gitboy16](https://discourse.julialang.org/u/gitboy16)\
**Replies:** 9\
**Last updated:** [June 14, 2025, 2:42am UTC](https://discourse.julialang.org/t/disable-extra-information-when-using-warn/129826 "2025-06-14T02:42:25Z")

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Hi, When I use @warn it prints the warning but also where it happened in the script. Is there a way to disable that information about the line in the script? Thank you.

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## [Loading 60k images from a folder. Python code is way faster than Julia](https://discourse.julialang.org/t/loading-60k-images-from-a-folder-python-code-is-way-faster-than-julia/129867)

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**Author:** [@AI\_hayasaka](https://discourse.julialang.org/u/AI_hayasaka)\
**Replies:** 11\
**Last updated:** [June 14, 2025, 1:31am UTC](https://discourse.julialang.org/t/loading-60k-images-from-a-folder-python-code-is-way-faster-than-julia/129867 "2025-06-14T01:31:25Z")

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This is the code i have currently: using Images function createDataset(path) X = \[\] y = \[\] for label in readdir(path) for file in readdir("$path/$label") img = load("$path/$label/$file") …

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## [Efficiency of abstract types vs \`Any\`](https://discourse.julialang.org/t/efficiency-of-abstract-types-vs-any/129518)

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**Author:** [@MilesCranmer](https://discourse.julialang.org/u/MilesCranmer)\
**Replies:** 13\
**Last updated:** [June 13, 2025, 11:02pm UTC](https://discourse.julialang.org/t/efficiency-of-abstract-types-vs-any/129518 "2025-06-13T23:02:21Z")

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This is a subtle point I wanted to learn a bit more about. I want to know all reasons why I might wish to write: # assume we have \`abstract type MyType end\` MyType\[x...\] Rather than Any\[x...\] Assuming we have: abst…

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## [Parametric constructor where type being constructed is parameter](https://discourse.julialang.org/t/parametric-constructor-where-type-being-constructed-is-parameter/129866)

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**Author:** [@luke-kiernan](https://discourse.julialang.org/u/luke-kiernan)\
**Replies:** 2\
**Last updated:** [June 13, 2025, 8:19pm UTC](https://discourse.julialang.org/t/parametric-constructor-where-type-being-constructed-is-parameter/129866 "2025-06-13T20:19:02Z")

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I have multiple structs (FooKey and BarKey), each of which has its own type parameter (FooType and BarType). Can I write the constructor for these structs in a parametrized manner? Here’s my attempt: abstract type AllTy…

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## [Translating Matlab to Julia](https://discourse.julialang.org/t/translating-matlab-to-julia/129864)

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**Author:** [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Replies:** 4\
**Last updated:** [June 13, 2025, 5:39pm UTC](https://discourse.julialang.org/t/translating-matlab-to-julia/129864 "2025-06-13T17:39:14Z")

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I am translating some code from Matlab to Julia. I found out that the author is using a lot of Matlab functions with the same name but different functionality, which are stored in different folders. Before using these …

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## [Model improvement](https://discourse.julialang.org/t/model-improvement/129855)

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**Author:** [@Smara\_Kazenango](https://discourse.julialang.org/u/Smara_Kazenango)\
**Replies:** 1\
**Last updated:** [June 13, 2025, 3:13pm UTC](https://discourse.julialang.org/t/model-improvement/129855 "2025-06-13T15:13:20Z")

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I am busy analysing the ‘medical\_tc\_test’ and medical\_tc\_train dataset and busy developing a model in Julia. Flux seems to provide very low accuracy and precision rates of below 10%. Has anyone worked on this dataset bef…

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## [Unable to calculate the gradient of opnorm/svdvals/svd on gpu?](https://discourse.julialang.org/t/unable-to-calculate-the-gradient-of-opnorm-svdvals-svd-on-gpu/129852)

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**Author:** [@camilodlt](https://discourse.julialang.org/u/camilodlt)\
**Replies:** 9\
**Last updated:** [June 13, 2025, 2:39pm UTC](https://discourse.julialang.org/t/unable-to-calculate-the-gradient-of-opnorm-svdvals-svd-on-gpu/129852 "2025-06-13T14:39:13Z")

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Hello, I’m able to calculate the gradients of the spectral norm in CPU but not in GPU :disappointed: This works fine : julia\> using CUDA, Zygote, LinearAlgebra julia\> X = randn(Float32, 5, 1); julia\> function snorm(…

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## [Documentation Formats - epub mobi pdf](https://discourse.julialang.org/t/documentation-formats-epub-mobi-pdf/7700)

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**Author:** [@guslen](https://discourse.julialang.org/u/guslen)\
**Replies:** 11\
**Last updated:** [June 13, 2025, 1:51pm UTC](https://discourse.julialang.org/t/documentation-formats-epub-mobi-pdf/7700 "2025-06-13T13:51:12Z")

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Hi, I was wondering, if there is any chance that you could publish an ebook-version for the documentation (docs.julialang.org) which is automatically generated? possible formats like: epub, pdf or mobi This would be u…

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## [Nothing == absence of keyword argument?](https://discourse.julialang.org/t/nothing-absence-of-keyword-argument/108119)

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**Author:** [@ryofurue](https://discourse.julialang.org/u/ryofurue)\
**Replies:** 15\
**Last updated:** [June 13, 2025, 1:35pm UTC](https://discourse.julialang.org/t/nothing-absence-of-keyword-argument/108119 "2025-06-13T13:35:30Z")

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Is there a convenient idiom to indicate that a keyword argument is absent? I imagine that somebody may have already invented a macro or something to do this . . . There are library functions, typically from graphics pa…

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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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## [Integrators with analytic derivatives w/r/t initial conditions (especially the independent variable)](https://discourse.julialang.org/t/integrators-with-analytic-derivatives-w-r-t-initial-conditions-especially-the-independent-variable/129832)

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**Author:** [@stevenhughes](https://discourse.julialang.org/u/stevenhughes)\
**Replies:** 2\
**Last updated:** [June 13, 2025, 12:43pm UTC](https://discourse.julialang.org/t/integrators-with-analytic-derivatives-w-r-t-initial-conditions-especially-the-independent-variable/129832 "2025-06-13T12:43:37Z")

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Hello, I am working on an application that requires derivatives odes to compute partials for solvers. The approach I am taking is to prefer analytic partials (for performance, which is key), and fallback to AD or finit…

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## [What programming language and algorithms should be taught in a first year undergraduate course in electrical engineering](https://discourse.julialang.org/t/what-programming-language-and-algorithms-should-be-taught-in-a-first-year-undergraduate-course-in-electrical-engineering/129803)

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**Author:** [@sibead](https://discourse.julialang.org/u/sibead)\
**Replies:** 15\
**Last updated:** [June 13, 2025, 12:55pm UTC](https://discourse.julialang.org/t/what-programming-language-and-algorithms-should-be-taught-in-a-first-year-undergraduate-course-in-electrical-engineering/129803 "2025-06-13T12:55:32Z")

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I am a professor at a German university in the Department of Electrical Engineering. Currently, our students take a mandatory course on the C programming language in their first term. Beyond that, there are no required p…

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## [IOError: stream is closed or unusable on POST](https://discourse.julialang.org/t/ioerror-stream-is-closed-or-unusable-on-post/129859)

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**Author:** [@ohmsweetohm1](https://discourse.julialang.org/u/ohmsweetohm1)\
**Replies:** 0\
**Last updated:** [June 13, 2025, 12:06pm UTC](https://discourse.julialang.org/t/ioerror-stream-is-closed-or-unusable-on-post/129859 "2025-06-13T12:06:25Z")

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I frequently get IOError: stream is closed or unusable when trying to POST to an API with a pretty large body: Content-Length: 406233. What can I do?

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## [Changing penalty parameter in objective function in JuMP](https://discourse.julialang.org/t/changing-penalty-parameter-in-objective-function-in-jump/129791)

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**Author:** [@Lester](https://discourse.julialang.org/u/Lester)\
**Replies:** 4\
**Last updated:** [June 13, 2025, 11:37am UTC](https://discourse.julialang.org/t/changing-penalty-parameter-in-objective-function-in-jump/129791 "2025-06-13T11:37:07Z")

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Hi Saying in JuMP, I want to a objective function being a conbination of the cost function f(x) and the constraint violation evaluation h(x), as @objective(model, Min, f(x) + μ \* h(x)). Is there a way for me to changeμ …

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## [Is it possible to reinterpret and reshape without allocating?](https://discourse.julialang.org/t/is-it-possible-to-reinterpret-and-reshape-without-allocating/129842)

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**Author:** [@AwesomeQuest](https://discourse.julialang.org/u/AwesomeQuest)\
**Replies:** 11\
**Last updated:** [June 13, 2025, 9:18am UTC](https://discourse.julialang.org/t/is-it-possible-to-reinterpret-and-reshape-without-allocating/129842 "2025-06-13T09:18:28Z")

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So I have data I’m getting over HTTP, r = rand(UInt8, 847296) It is arraigned in 3 8 byte chunks, where the first chunk is unwanted metadata, so every 3n -2 chunks is unwanted. I have written a function that does this…

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## [Acausal component based modelling including neural network components](https://discourse.julialang.org/t/acausal-component-based-modelling-including-neural-network-components/99111)

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**Author:** [@Dhruva2](https://discourse.julialang.org/u/Dhruva2)\
**Replies:** 9\
**Last updated:** [June 13, 2025, 8:58am UTC](https://discourse.julialang.org/t/acausal-component-based-modelling-including-neural-network-components/99111 "2025-06-13T08:58:18Z")

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Hello all, A high level question. I want to do acausal, component-based modelling as on the ModelingToolkit.jl docs. In particular, I want to include some components that are neural networks. IE build a ‘universal dif…

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## [Define a recursive JuMP.@expression](https://discourse.julialang.org/t/define-a-recursive-jump-expression/129848)

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**Author:** [@WalterMadelim](https://discourse.julialang.org/u/WalterMadelim)\
**Replies:** 3\
**Last updated:** [June 13, 2025, 3:35am UTC](https://discourse.julialang.org/t/define-a-recursive-jump-expression/129848 "2025-06-13T03:35:35Z")

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Is this a good syntax that can be supported? julia\> using JuMP; model = Model(); julia\> x0 = 1.3; # initial state julia\> @variable(model, u\[t = 1:3\], Bin); # actions julia\> @expression(model, x\[t = 1:3\], (t == 1 ? x0…

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