# Latest

**URL:** https://discourse.julialang.org/latest.md?page=140

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

**Page:** 141

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## [Differentiate through SecondOrderCone](https://discourse.julialang.org/t/differentiate-through-secondordercone/130365)

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**Author:** [@gustave\_Robichon](https://discourse.julialang.org/u/gustave_Robichon)\
**Replies:** 8\
**Last updated:** [July 4, 2025, 10:45am UTC](https://discourse.julialang.org/t/differentiate-through-secondordercone/130365 "2025-07-04T10:45:14Z")

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Hello :slight\_smile: I want to differentiate an Optimization Program. I use DiffOpt for this, which is built over JuMP. I have some data, that I want to fit by a function of a few parameters. This can be done with diffe…

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## [How far does type instability propagate?](https://discourse.julialang.org/t/how-far-does-type-instability-propagate/130350)

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**Author:** [@Leo\_I](https://discourse.julialang.org/u/Leo_I)\
**Replies:** 10\
**Last updated:** [July 4, 2025, 8:37am UTC](https://discourse.julialang.org/t/how-far-does-type-instability-propagate/130350 "2025-07-04T08:37:38Z")

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I have a function type\_uint(val::Integer) ::Type{\<:Unsigned} which returns the smallest UInt type that can still represent val without overflowing. I use this everywhere in my code, but only at top level. For example, g…

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## [Plot recipes with nested subplots](https://discourse.julialang.org/t/plot-recipes-with-nested-subplots/130465)

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**Author:** [@polhager](https://discourse.julialang.org/u/polhager)\
**Replies:** 0\
**Last updated:** [July 4, 2025, 8:20am UTC](https://discourse.julialang.org/t/plot-recipes-with-nested-subplots/130465 "2025-07-04T08:20:08Z")

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Hi. I have a custom data type which, after doing some calculations on, I would like to plot in a specific way. A basic example of the setup is this: struct Data x y1s y2s end x = 1:10 y1s = \[\[rand(10) for \_…

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## [How to parameterize StepRangeLen](https://discourse.julialang.org/t/how-to-parameterize-steprangelen/130338)

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**Author:** [@mwlidar](https://discourse.julialang.org/u/mwlidar)\
**Replies:** 3\
**Last updated:** [July 4, 2025, 7:47am UTC](https://discourse.julialang.org/t/how-to-parameterize-steprangelen/130338 "2025-07-04T07:47:41Z")

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I have a structure with a floating point type parameter for the arrays and I want to include a StepRangeLen with fitting type. How can this be achieved? struct MyType{S\<:Union{Float32, Float64}} data::Vector{S} grid…

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## [Huge performance variance with \`if\` options in loops](https://discourse.julialang.org/t/huge-performance-variance-with-if-options-in-loops/130462)

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**Author:** [@hz-xiaxz](https://discourse.julialang.org/u/hz-xiaxz)\
**Replies:** 4\
**Last updated:** [July 4, 2025, 6:51am UTC](https://discourse.julialang.org/t/huge-performance-variance-with-if-options-in-loops/130462 "2025-07-04T06:51:35Z")

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I’m trying to optimize a non-allocating matrix update. Here is the simple code. function update\_W\_original!( W::AbstractMatrix, l::Int, K::Int, col\_cache::AbstractVector, row\_cache::AbstractVector, )…

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## [Order of Base.convert calls with \`@kwdef\` constructors](https://discourse.julialang.org/t/order-of-base-convert-calls-with-kwdef-constructors/130460)

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**Author:** [@Lincoln\_Hannah](https://discourse.julialang.org/u/Lincoln_Hannah)\
**Replies:** 4\
**Last updated:** [July 4, 2025, 5:22am UTC](https://discourse.julialang.org/t/order-of-base-convert-calls-with-kwdef-constructors/130460 "2025-07-04T05:22:38Z")

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Base.convert( ::Type{Int64}, x::AbstractString ) = parse(Int64,x) @kwdef struct X a::Int64 b::Int64=a+1 end X(a="1") ERROR: MethodError: no method matching +(::String, ::Int64) Can I make the conversion pars…

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## [Package for dealing with symmetric matrices efficiently](https://discourse.julialang.org/t/package-for-dealing-with-symmetric-matrices-efficiently/130413)

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**Author:** [@Joris\_Pinkse](https://discourse.julialang.org/u/Joris_Pinkse)\
**Replies:** 9\
**Last updated:** [July 4, 2025, 2:07am UTC](https://discourse.julialang.org/t/package-for-dealing-with-symmetric-matrices-efficiently/130413 "2025-07-04T02:07:16Z")

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The Julia Symmetric Matrix type stores the full matrix. I’m looking for a package that offers a way to store and to index into a symmetric matrix directly but only stores one triangle, but that is performant, operates a…

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## [NumPy is faster than Julia 1.11 for maximum function](https://discourse.julialang.org/t/numpy-is-faster-than-julia-1-11-for-maximum-function/130451)

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**Author:** [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Replies:** 25\
**Last updated:** [July 4, 2025, 2:02am UTC](https://discourse.julialang.org/t/numpy-is-faster-than-julia-1-11-for-maximum-function/130451 "2025-07-04T02:02:57Z")

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import numpy as np A = np.rand(2026,51,251) # %timeit np.max(A) # 4.49 ms ± 89.2 μs per loop (mean ± std. dev. of 7 runs, 100 loops each) Julia code: using BenchmarkTools const A=rand(2026,51,251) @btime maximum(A) # …

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## [Gurobi reports OPTIMAL on a QP having a huge MaxVio](https://discourse.julialang.org/t/gurobi-reports-optimal-on-a-qp-having-a-huge-maxvio/129645)

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**Author:** [@WalterMadelim](https://discourse.julialang.org/u/WalterMadelim)\
**Replies:** 8\
**Last updated:** [July 4, 2025, 1:08am UTC](https://discourse.julialang.org/t/gurobi-reports-optimal-on-a-qp-having-a-huge-maxvio/129645 "2025-07-04T01:08:16Z")

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julia\> JuMP.unset\_silent(outer) Set parameter OutputFlag to value 1 julia\> JuMP.optimize!(outer) Gurobi Optimizer version 12.0.2 build v12.0.2rc0 (win64 - Windows 11.0 (26100.2)) CPU model: 11th Gen Intel(R) Core(TM) i…

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## [Dictionaries and such](https://discourse.julialang.org/t/dictionaries-and-such/130443)

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**Author:** [@skypuppy](https://discourse.julialang.org/u/skypuppy)\
**Replies:** 9\
**Last updated:** [July 3, 2025, 9:12pm UTC](https://discourse.julialang.org/t/dictionaries-and-such/130443 "2025-07-03T21:12:45Z")

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I hated using dictionaries in Python, mostly because they in-memory only. I guess I am so accustomed to relational DBMS’s that I just can’t think any other way. So, truly, are dictionaries that useful in Julia? Are th…

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## [\[ANN\] SPHExample - A teaching package for small SPH dam-break simulations](https://discourse.julialang.org/t/ann-sphexample-a-teaching-package-for-small-sph-dam-break-simulations/92666)

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**Author:** [@Ahmed\_Salih](https://discourse.julialang.org/u/Ahmed_Salih)\
**Replies:** 19\
**Last updated:** [July 3, 2025, 8:50pm UTC](https://discourse.julialang.org/t/ann-sphexample-a-teaching-package-for-small-sph-dam-break-simulations/92666 "2025-07-03T20:50:49Z")

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Hi everyone! First time doing this sort of annoucement so a bit excited and nervous :slight\_smile: I’d like to announce a new package that I’ve been working on: an SPH (Smoothed Particle Hydrodynamics) dam-break simula…

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## [On the relationship between \`JuMP\` and \`MathOptInterface\`](https://discourse.julialang.org/t/on-the-relationship-between-jump-and-mathoptinterface/130329)

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**Author:** [@WuSiren](https://discourse.julialang.org/u/WuSiren)\
**Replies:** 11\
**Last updated:** [July 3, 2025, 6:12pm UTC](https://discourse.julialang.org/t/on-the-relationship-between-jump-and-mathoptinterface/130329 "2025-07-03T18:12:08Z")

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JuMP is essentially a more user-friendly wrapper for MathOptInterface and it can be completely bypassed or replaced by MathOptInterface, right?

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## [Learning to program in Julia, using a powerful debugger](https://discourse.julialang.org/t/learning-to-program-in-julia-using-a-powerful-debugger/130453)

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**Author:** [@skypuppy](https://discourse.julialang.org/u/skypuppy)\
**Replies:** 3\
**Last updated:** [July 3, 2025, 5:47pm UTC](https://discourse.julialang.org/t/learning-to-program-in-julia-using-a-powerful-debugger/130453 "2025-07-03T17:47:06Z")

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Does there exist one? What I’d like to use is the equivalent of a C good debugger for Julia (See SGI’s graphical debugger for examples.. To help me learn Julia, I (the generic ‘I’) could open a package that interests m…

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## [In-place SciMLOperators](https://discourse.julialang.org/t/in-place-scimloperators/130457)

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**Author:** [@fdekerme](https://discourse.julialang.org/u/fdekerme)\
**Replies:** 0\
**Last updated:** [July 3, 2025, 5:19pm UTC](https://discourse.julialang.org/t/in-place-scimloperators/130457 "2025-07-03T17:19:02Z")

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Hello :grinning:, Can anyone tell me more about SciMLOperators.jl’s in-place operations? using SciMLOperators using BenchmarkTools function Afunc!(w,v,u,p,t) w\[1\] = -2v\[1\] + v\[2\] for i in 2:4 w\[i\] = v\[…

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## [How to specify the nonlinear solver algorithm for Shooting and MultipleShooting BVP solvers](https://discourse.julialang.org/t/how-to-specify-the-nonlinear-solver-algorithm-for-shooting-and-multipleshooting-bvp-solvers/130392)

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**Author:** [@ThermionicsGuy](https://discourse.julialang.org/u/ThermionicsGuy)\
**Replies:** 5\
**Last updated:** [July 3, 2025, 4:40pm UTC](https://discourse.julialang.org/t/how-to-specify-the-nonlinear-solver-algorithm-for-shooting-and-multipleshooting-bvp-solvers/130392 "2025-07-03T16:40:05Z")

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SciML’s documentation suggests that the boundary value problem solvers Shooting() and MultipleShooting() should be able to use any of the NonlinearSolve.jl algorithms, but I haven’t been able to find a way to specify the…

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## [Significant difference in SCIP solving time between JuMP and Rust (\`russcip\`)](https://discourse.julialang.org/t/significant-difference-in-scip-solving-time-between-jump-and-rust-russcip/130455)

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**Author:** [@ShugarSkull](https://discourse.julialang.org/u/ShugarSkull)\
**Replies:** 2\
**Last updated:** [July 3, 2025, 3:52pm UTC](https://discourse.julialang.org/t/significant-difference-in-scip-solving-time-between-jump-and-rust-russcip/130455 "2025-07-03T15:52:32Z")

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Hi all, I’ve noticed a large difference in solving time when using SCIP through JuMP in Julia versus using the russcip crate in Rust, and I’m hoping someone can help explain why. :puzzle\_piece: Context I’m solving a MI…

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## [Efficient vectorization in Turing.jl](https://discourse.julialang.org/t/efficient-vectorization-in-turing-jl/130390)

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**Author:** [@contejuz](https://discourse.julialang.org/u/contejuz)\
**Replies:** 1\
**Last updated:** [July 3, 2025, 3:25pm UTC](https://discourse.julialang.org/t/efficient-vectorization-in-turing-jl/130390 "2025-07-03T15:25:38Z")

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I have a fairly simple hierarchical model where I have 2 population parameters a,b. b is also an individual level parameters such that the b\_i are sampled from a distribution parametrized by b. a and b\_i govern the shape…

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## [Organized package list that includes a synopsys of the package function?](https://discourse.julialang.org/t/organized-package-list-that-includes-a-synopsys-of-the-package-function/130452)

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**Author:** [@skypuppy](https://discourse.julialang.org/u/skypuppy)\
**Replies:** 1\
**Last updated:** [July 3, 2025, 2:09pm UTC](https://discourse.julialang.org/t/organized-package-list-that-includes-a-synopsys-of-the-package-function/130452 "2025-07-03T14:09:08Z")

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Is there an organized package list somewhere? Esp one that includes a short synopsis of that the package is about? (Who it was written for?) Ideally with an index sorted by name and one by purpose? With more than 5,0…

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## [Stochastic differential equations: how to improve the exactness of the solution?](https://discourse.julialang.org/t/stochastic-differential-equations-how-to-improve-the-exactness-of-the-solution/130379)

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**Author:** [@Marco\_Masi](https://discourse.julialang.org/u/Marco_Masi)\
**Replies:** 6\
**Last updated:** [July 3, 2025, 12:27pm UTC](https://discourse.julialang.org/t/stochastic-differential-equations-how-to-improve-the-exactness-of-the-solution/130379 "2025-07-03T12:27:09Z")

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I’m trying to find out how to integrate stochastic differential equations. I would like to see how an ODE that I have already solved behaves when subjected to a noisy signal. I wrote the code below. I don’t know if it is…

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## [Missing dylib , MacOS Sequoia, can't install 1.11](https://discourse.julialang.org/t/missing-dylib-macos-sequoia-cant-install-1-11/130416)

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**Author:** [@cellocgw](https://discourse.julialang.org/u/cellocgw)\
**Replies:** 9\
**Last updated:** [July 3, 2025, 12:19pm UTC](https://discourse.julialang.org/t/missing-dylib-macos-sequoia-cant-install-1-11/130416 "2025-07-03T12:19:12Z")

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Trying the “curl” command string, I get dyld\[33001\]: Library not loaded: /opt/local/lib/libssl.1.0.0.dylib Referenced from: \<2377B937-C59E-C708-1A33-0F668A90829B\> /opt/local/bin/curl Reason: tried: ‘/opt/local/lib/li…

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## [Negative false no longer acts as a strong zero](https://discourse.julialang.org/t/negative-false-no-longer-acts-as-a-strong-zero/128506)

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**Author:** [@lance\_xwq](https://discourse.julialang.org/u/lance_xwq)\
**Replies:** 23\
**Last updated:** [July 3, 2025, 11:06am UTC](https://discourse.julialang.org/t/negative-false-no-longer-acts-as-a-strong-zero/128506 "2025-07-03T11:06:19Z")

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Julia documentation states that false acts like a strong zero in multiplication, such that NaN \* false produces 0.0. However, Julia also defines -(x::Bool) = -Int(x), which seems to indicate -false is no longer a strong …

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## [Makie: manual colorbar tick values and tick labels](https://discourse.julialang.org/t/makie-manual-colorbar-tick-values-and-tick-labels/130437)

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**Author:** [@tduretz](https://discourse.julialang.org/u/tduretz)\
**Replies:** 1\
**Last updated:** [July 3, 2025, 8:25am UTC](https://discourse.julialang.org/t/makie-manual-colorbar-tick-values-and-tick-labels/130437 "2025-07-03T08:25:51Z")

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Hello, I was wondering how to set manual colorbar tick values and tick labels when using categorical colormap in Makie. I have prepared an MWE below. The data I want plot contain numeric values (1, 2, 3, 4) and NaN valu…

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## [Cannot install Fermi.jl due to version constraints](https://discourse.julialang.org/t/cannot-install-fermi-jl-due-to-version-constraints/130157)

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**Author:** [@Uranium238](https://discourse.julialang.org/u/Uranium238)\
**Replies:** 4\
**Last updated:** [July 3, 2025, 6:03am UTC](https://discourse.julialang.org/t/cannot-install-fermi-jl-due-to-version-constraints/130157 "2025-07-03T06:03:00Z")

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I am trying to install Fermi.jl on the newest stable release of Julia. On doing a fresh install and activating a completely new environment, when I do \] add Fermi, I am met with the following error message : (@v1.11) pk…

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## [Postdoc position in methods development for modeling in quantum information science](https://discourse.julialang.org/t/postdoc-position-in-methods-development-for-modeling-in-quantum-information-science/130434)

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**Author:** [@Krastanov](https://discourse.julialang.org/u/Krastanov)\
**Replies:** 0\
**Last updated:** [July 3, 2025, 12:50am UTC](https://discourse.julialang.org/t/postdoc-position-in-methods-development-for-modeling-in-quantum-information-science/130434 "2025-07-03T00:50:52Z")

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Postdoc Position in Quantum Information Science at UMass Amherst The Quantum Information team at UMass Amherst is involved with modeling and optimization of quantum hardware, as well as development of new modeling metho…

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## [Arceus.jl — A Lightning-Fast Behavior Resolution System](https://discourse.julialang.org/t/arceus-jl-a-lightning-fast-behavior-resolution-system/130321)

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**Author:** [@Gesee](https://discourse.julialang.org/u/Gesee)\
**Replies:** 24\
**Last updated:** [July 3, 2025, 12:12am UTC](https://discourse.julialang.org/t/arceus-jl-a-lightning-fast-behavior-resolution-system/130321 "2025-07-03T00:12:58Z")

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Hi all, I’m happy to present Arceus.jl, a fork of a high-performance AliceRoselia’s original package Arceus, which introduces a novel way to resolve behaviors for entities based on their component sets—using magic bitbo…

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## [Best-fit parameter error bar using Optimization.jl?](https://discourse.julialang.org/t/best-fit-parameter-error-bar-using-optimization-jl/103186)

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**Author:** [@abehersan](https://discourse.julialang.org/u/abehersan)\
**Replies:** 18\
**Last updated:** [July 2, 2025, 10:18pm UTC](https://discourse.julialang.org/t/best-fit-parameter-error-bar-using-optimization-jl/103186 "2025-07-02T22:18:01Z")

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Specifically in the context of local solvers with and without constraints. What is the standard way people report error bars on fitting parameters while using Optimization.jl? In principle this can be calculated if the…

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## [Tips for displaying plots in terminals with varying support](https://discourse.julialang.org/t/tips-for-displaying-plots-in-terminals-with-varying-support/130404)

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**Author:** [@Benny](https://discourse.julialang.org/u/Benny)\
**Replies:** 4\
**Last updated:** [July 2, 2025, 9:36pm UTC](https://discourse.julialang.org/t/tips-for-displaying-plots-in-terminals-with-varying-support/130404 "2025-07-02T21:36:40Z")

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Usually I use a notebook or save plots to images to open in an another application, but given that the practicality of AOT-compiled executables could improve drastically soon, I started looking into displaying a practica…

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## [Ldiv for Cholesky is slower than two substitutions](https://discourse.julialang.org/t/ldiv-for-cholesky-is-slower-than-two-substitutions/130092)

<div class="topic-metadata">

**Author:** [@stepanzh](https://discourse.julialang.org/u/stepanzh)\
**Replies:** 13\
**Last updated:** [July 2, 2025, 9:09pm UTC](https://discourse.julialang.org/t/ldiv-for-cholesky-is-slower-than-two-substitutions/130092 "2025-07-02T21:09:15Z")

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I’ve faced that ldiv for Cholesky is unexpectedly slower than two substitutions. Here is a test problem with a random 1000-by-1000 Matrix{Float64}. julia\> using BenchmarkTools, LinearAlgebra julia\> n = 1000; A = rand(…

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## [Mapping Linear Indices to Cartesian Indices](https://discourse.julialang.org/t/mapping-linear-indices-to-cartesian-indices/130424)

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**Author:** [@prconlin](https://discourse.julialang.org/u/prconlin)\
**Replies:** 5\
**Last updated:** [July 2, 2025, 8:40pm UTC](https://discourse.julialang.org/t/mapping-linear-indices-to-cartesian-indices/130424 "2025-07-02T20:40:32Z")

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Hello, I’m working with matrices in such a way that I want to be able to access values by both the Cartesian and linear Indices. I want to be able to map any given linear index to its Cartesian counterpart and vice ver…

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## [PlotlyJS update subplot traces in-place](https://discourse.julialang.org/t/plotlyjs-update-subplot-traces-in-place/130432)

<div class="topic-metadata">

**Author:** [@rand5](https://discourse.julialang.org/u/rand5)\
**Replies:** 1\
**Last updated:** [July 2, 2025, 8:35pm UTC](https://discourse.julialang.org/t/plotlyjs-update-subplot-traces-in-place/130432 "2025-07-02T20:35:43Z")

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In PlotlyJS, I can update a trace in-place using react!() as mentioned in the docs: tr = scatter(;y=rand(5)) p = plot(tr) tr\[:y\] .= rand(5) react!(p,\[tr\],Layout()) However, I don’t see any information on how to do in-p…

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