# Latest

**URL:** https://discourse.julialang.org/latest.md?page=285

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

**Page:** 286

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## [Plotting 2D histogram with different bins for each dimension](https://discourse.julialang.org/t/plotting-2d-histogram-with-different-bins-for-each-dimension/1790)

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**Author:** [@rwgardner](https://discourse.julialang.org/u/rwgardner)\
**Replies:** 4\
**Last updated:** [November 2, 2024, 11:11am UTC](https://discourse.julialang.org/t/plotting-2d-histogram-with-different-bins-for-each-dimension/1790 "2024-11-02T11:11:22Z")

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I’m trying to plot a 2D histogram where the 2 dimensions have different bins. I’m currently using marginalhist(x, x, fc=:plasma, bins=\[0.0, 1.0, 2.0\], legend=true) from PlotRecipes (although I’m not tied to that). Th…

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## [Developing Julia on a moderate laptop is very tedious](https://discourse.julialang.org/t/developing-julia-on-a-moderate-laptop-is-very-tedious/121987)

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**Author:** [@schlichtanders](https://discourse.julialang.org/u/schlichtanders)\
**Replies:** 20\
**Last updated:** [November 2, 2024, 11:06am UTC](https://discourse.julialang.org/t/developing-julia-on-a-moderate-laptop-is-very-tedious/121987 "2024-11-02T11:06:16Z")

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Hi there, I like to gather how other people develop julia packages. I so frequently run into the point where I changed a struct field name or const and need to restart julia, with compilation times which make me a bit s…

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## [Julia equivalent of the \`.venv\` folder when working with Pkg and environments](https://discourse.julialang.org/t/julia-equivalent-of-the-venv-folder-when-working-with-pkg-and-environments/122123)

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**Author:** [@world-peace](https://discourse.julialang.org/u/world-peace)\
**Replies:** 11\
**Last updated:** [November 2, 2024, 10:33am UTC](https://discourse.julialang.org/t/julia-equivalent-of-the-venv-folder-when-working-with-pkg-and-environments/122123 "2024-11-02T10:33:19Z")

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I have realized I am a little confused about one aspect of the behavior of Pkg. In Python, local virtual environments are provided by venv. (Other tools also exist.) You use Python to run venv, which is a globally acce…

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## [What's recommended literature on high-performance Julia?](https://discourse.julialang.org/t/whats-recommended-literature-on-high-performance-julia/122145)

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**Author:** [@Olegg](https://discourse.julialang.org/u/Olegg)\
**Replies:** 6\
**Last updated:** [November 2, 2024, 6:31am UTC](https://discourse.julialang.org/t/whats-recommended-literature-on-high-performance-julia/122145 "2024-11-02T06:31:14Z")

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There’s the book Julia High Performance: Optimizations, distributed computing, multithreading, and GPU programming with Julia 1.0 and beyond. 2nd edition from 2019. (It’s probably by @avik) Would it be useful for Julia …

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## [How to call inplace (! convention) functions with JuliaCall?](https://discourse.julialang.org/t/how-to-call-inplace-convention-functions-with-juliacall/122155)

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**Author:** [@marcsgil](https://discourse.julialang.org/u/marcsgil)\
**Replies:** 3\
**Last updated:** [November 1, 2024, 11:13pm UTC](https://discourse.julialang.org/t/how-to-call-inplace-convention-functions-with-juliacall/122155 "2024-11-01T23:13:31Z")

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Hello! I’m trying to wrap a Julia package in Python using JuliaCall.jl. I have many functions in Julia that have both an in place version f!, and a corresponding out of place f. Unfortunately, one cannot have ! in as p…

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## [Is there a sparse array with 'missing' as default](https://discourse.julialang.org/t/is-there-a-sparse-array-with-missing-as-default/122095)

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**Author:** [@feanor12](https://discourse.julialang.org/u/feanor12)\
**Replies:** 1\
**Last updated:** [October 31, 2024, 10:26pm UTC](https://discourse.julialang.org/t/is-there-a-sparse-array-with-missing-as-default/122095 "2024-10-31T22:26:58Z")

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something like : \[missing,1.5,missing,missing\] where only 2 =\> 1.5 is stored?

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## [Check if default sysimage is used](https://discourse.julialang.org/t/check-if-default-sysimage-is-used/122152)

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**Author:** [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Replies:** 1\
**Last updated:** [November 1, 2024, 9:05pm UTC](https://discourse.julialang.org/t/check-if-default-sysimage-is-used/122152 "2024-11-01T21:05:42Z")

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Is there a way to determine in Julia if the default system image or a custom system image is currently used?

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## [How does one have multiple random variables in an SDEProblem?](https://discourse.julialang.org/t/how-does-one-have-multiple-random-variables-in-an-sdeproblem/122066)

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**Author:** [@AwesomeQuest](https://discourse.julialang.org/u/AwesomeQuest)\
**Replies:** 2\
**Last updated:** [November 1, 2024, 8:15pm UTC](https://discourse.julialang.org/t/how-does-one-have-multiple-random-variables-in-an-sdeproblem/122066 "2024-11-01T20:15:21Z")

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I’m trying to simulate a stochastic state space model which looks something like: x\_dot(x) = A\*x + B\*u(x + n) + d A and B are matrices, x, n, and d are vectors and u is an affine function. Each of the elements of n an…

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## [Threading over permutations](https://discourse.julialang.org/t/threading-over-permutations/122149)

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**Author:** [@tg570](https://discourse.julialang.org/u/tg570)\
**Replies:** 2\
**Last updated:** [November 1, 2024, 8:12pm UTC](https://discourse.julialang.org/t/threading-over-permutations/122149 "2024-11-01T20:12:56Z")

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I am trying to parallelize a loop over the Combinatorics permutations(1:n) without using collect() since the permutations I am working with are too big and they cause memory issues. I think there is a problem with just u…

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## [Storing the LU decomposition of a matrix](https://discourse.julialang.org/t/storing-the-lu-decomposition-of-a-matrix/122138)

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**Author:** [@Gattu\_Mytraya](https://discourse.julialang.org/u/Gattu_Mytraya)\
**Replies:** 5\
**Last updated:** [November 1, 2024, 7:57pm UTC](https://discourse.julialang.org/t/storing-the-lu-decomposition-of-a-matrix/122138 "2024-11-01T19:57:46Z")

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Hi! I have a calculation in which I need the determinant and possibly the inverse of a matrix (let’s call it X). I am, therefore, trying to store the LU decomposition of X and then use it later. To this end, I have the …

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## [Is there a way to read a DataFrame from file specifying the type of each column?](https://discourse.julialang.org/t/is-there-a-way-to-read-a-dataframe-from-file-specifying-the-type-of-each-column/122146)

<div class="topic-metadata">

**Author:** [@world-peace](https://discourse.julialang.org/u/world-peace)\
**Replies:** 7\
**Last updated:** [November 1, 2024, 7:37pm UTC](https://discourse.julialang.org/t/is-there-a-way-to-read-a-dataframe-from-file-specifying-the-type-of-each-column/122146 "2024-11-01T19:37:19Z")

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Here is some code which reads a DataFrame from a (csv) file: using DataFrames using CSV df = DataFrame(CSV.File(filename)) By default, I think the columns are String type. (Maybe it is inferred from the data values?) …

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## [OpenCV.jl: OpenCV's Julia Bindings](https://discourse.julialang.org/t/opencv-jl-opencvs-julia-bindings/99853)

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**Author:** [@Ashwani\_Rathee](https://discourse.julialang.org/u/Ashwani_Rathee)\
**Replies:** 15\
**Last updated:** [November 1, 2024, 6:27pm UTC](https://discourse.julialang.org/t/opencv-jl-opencvs-julia-bindings/99853 "2024-11-01T18:27:31Z")

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OpenCV.jl OpenCV.jl is a Julia package that provides an interface to the popular computer vision library OpenCV. It allows Julia users to leverage the extensive functionalities and algorithms offered by OpenCV for vario…

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## [Missing \`println\` output with \`wait(::Event); println("done")\`](https://discourse.julialang.org/t/missing-println-output-with-wait-event-println-done/122137)

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**Author:** [@SunnyUser](https://discourse.julialang.org/u/SunnyUser)\
**Replies:** 3\
**Last updated:** [November 1, 2024, 6:21pm UTC](https://discourse.julialang.org/t/missing-println-output-with-wait-event-println-done/122137 "2024-11-01T18:21:09Z")

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Hi all :slight\_smile: Can you check if the done2 is also missing for you? Here is my code: julia\> e = Base.Event() Base.Event(Base.GenericCondition{ReentrantLock}(Base.IntrusiveLinkedList{Task}(nothing, nothing), Reen…

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## [REPL not found on Julia v1.11.1](https://discourse.julialang.org/t/repl-not-found-on-julia-v1-11-1/122120)

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**Author:** [@ohmsweetohm1](https://discourse.julialang.org/u/ohmsweetohm1)\
**Replies:** 3\
**Last updated:** [November 1, 2024, 5:16pm UTC](https://discourse.julialang.org/t/repl-not-found-on-julia-v1-11-1/122120 "2024-11-01T17:16:02Z")

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Seeing this on my test jobs after updating Julia ERROR: KeyError: key "REPL" not found Stacktrace: \[1\] getindex @ ./dict.jl:477 \[inlined\] \[2\] Base.Precompilation.ExplicitEnv(envpath::String) @ Base.Precompil…

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## [Adding a type parameter annotation symbol that preserves the original bound](https://discourse.julialang.org/t/adding-a-type-parameter-annotation-symbol-that-preserves-the-original-bound/122015)

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**Author:** [@frankwswang](https://discourse.julialang.org/u/frankwswang)\
**Replies:** 16\
**Last updated:** [November 1, 2024, 4:56pm UTC](https://discourse.julialang.org/t/adding-a-type-parameter-annotation-symbol-that-preserves-the-original-bound/122015 "2024-11-01T16:56:29Z")

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Given a defined composite type with multiple constrained type parameters, e.g.: julia\> struct myT{T1\<:Real, T2\<:Integer} end When we reference its type signature elsewhere (e.g., for a method definition), it’s common t…

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## [Why this function involving eachslice is type unstable?](https://discourse.julialang.org/t/why-this-function-involving-eachslice-is-type-unstable/122083)

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**Author:** [@Oleg\_Soloviev](https://discourse.julialang.org/u/Oleg_Soloviev)\
**Replies:** 2\
**Last updated:** [November 1, 2024, 3:46pm UTC](https://discourse.julialang.org/t/why-this-function-involving-eachslice-is-type-unstable/122083 "2024-11-01T15:46:34Z")

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I need to perform iteratively some operations slicewise in a multidimensional array, and I cannot make it type stable. Here is an MWE in follow-up to the examples from eachslice is type unstable · Issue #39639 · JuliaLa…

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## [Create a more unified syntax for requesting a specific return type of functions?](https://discourse.julialang.org/t/create-a-more-unified-syntax-for-requesting-a-specific-return-type-of-functions/122067)

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**Author:** [@stephancb](https://discourse.julialang.org/u/stephancb)\
**Replies:** 18\
**Last updated:** [November 1, 2024, 3:33pm UTC](https://discourse.julialang.org/t/create-a-more-unified-syntax-for-requesting-a-specific-return-type-of-functions/122067 "2024-11-01T15:33:19Z")

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round(1.1) --\> 1.0 round(Int, 1.1) --\> 1 works, but not sqrt(Complex, -1) acos(Complex, 1.1) ... and other inverse trigonometric functions where the real domain is limited. In these cases the desired result is obtaina…

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## [Understanding Julia Environments - Project Environment and Package Directory](https://discourse.julialang.org/t/understanding-julia-environments-project-environment-and-package-directory/122082)

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**Author:** [@world-peace](https://discourse.julialang.org/u/world-peace)\
**Replies:** 9\
**Last updated:** [November 1, 2024, 2:59pm UTC](https://discourse.julialang.org/t/understanding-julia-environments-project-environment-and-package-directory/122082 "2024-11-01T14:59:13Z")

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I am trying to understand this documentation page which is related to code loading in Julia. Under the Environment section, there are two types of environment listed. Project Environment Package Directory I don’t u…

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## [Docstring being replaced](https://discourse.julialang.org/t/docstring-being-replaced/122129)

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**Author:** [@fmario](https://discourse.julialang.org/u/fmario)\
**Replies:** 0\
**Last updated:** [November 1, 2024, 1:11pm UTC](https://discourse.julialang.org/t/docstring-being-replaced/122129 "2024-11-01T13:11:49Z")

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I make the following module: module Foo export Bar """ Bar Struct bar docstring. """ struct Bar n::Int @doc """ Bar(n::Int) Constructor docstring. """ function Bar(n::Int) …

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## [Creating a new package version fails](https://discourse.julialang.org/t/creating-a-new-package-version-fails/122128)

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**Author:** [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Replies:** 3\
**Last updated:** [November 1, 2024, 12:55pm UTC](https://discourse.julialang.org/t/creating-a-new-package-version-fails/122128 "2024-11-01T12:55:11Z")

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I tried to release a new package version, which fails: The real problem is that there is no error message. How can I find out why it fails?

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## [Impossible to perform autodiff on simple ODE](https://discourse.julialang.org/t/impossible-to-perform-autodiff-on-simple-ode/120861)

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**Author:** [@albertomercurio](https://discourse.julialang.org/u/albertomercurio)\
**Replies:** 22\
**Last updated:** [November 1, 2024, 10:47am UTC](https://discourse.julialang.org/t/impossible-to-perform-autodiff-on-simple-ode/120861 "2024-11-01T10:47:16Z")

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Hello, I was trying to differentiate a simple ODE using Zygote.jl, but it returns the following error: ERROR: \`p\` is not a SciMLStructure. This is required for adjoint sensitivity analysis. For more information, see th…

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## [Reusing a JuMP \`Model\` for several, different optimization problems](https://discourse.julialang.org/t/reusing-a-jump-model-for-several-different-optimization-problems/122031)

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**Author:** [@tchr](https://discourse.julialang.org/u/tchr)\
**Replies:** 9\
**Last updated:** [November 1, 2024, 10:29am UTC](https://discourse.julialang.org/t/reusing-a-jump-model-for-several-different-optimization-problems/122031 "2024-11-01T10:29:53Z")

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I am using JuMP to solve many (~tens to hundreds of thousands) small integer-feasibility problems (variants of a subset sum problem). Each individual problem is parameterized by different integers but the structure is qu…

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## [Why isn't this legal syntax for defining a subtype?](https://discourse.julialang.org/t/why-isnt-this-legal-syntax-for-defining-a-subtype/121479)

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**Author:** [@xiaodai](https://discourse.julialang.org/u/xiaodai)\
**Replies:** 16\
**Last updated:** [November 1, 2024, 9:43am UTC](https://discourse.julialang.org/t/why-isnt-this-legal-syntax-for-defining-a-subtype/121479 "2024-11-01T09:43:14Z")

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I have some abstract type parameterised by a T type like this abstract type SomeAbstractType{T} end and I want to create a subtype from it and this syntax works mutable struct Some{T\<:Number} \<: SomeAbstractType{T} …

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## [Getting the dimension value at eachslice of a DimArray](https://discourse.julialang.org/t/getting-the-dimension-value-at-eachslice-of-a-dimarray/122088)

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**Author:** [@gmcardle](https://discourse.julialang.org/u/gmcardle)\
**Replies:** 1\
**Last updated:** [November 1, 2024, 9:29am UTC](https://discourse.julialang.org/t/getting-the-dimension-value-at-eachslice-of-a-dimarray/122088 "2024-11-01T09:29:06Z")

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Hi, I’m still getting to grips with practical use of DimensionalData.jl DimArray types. Suppose I’m using eachslice to iterate over the time dimension of a 3D array, but I want to get the time value at each slice. What…

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## [How to do high precision linear algebra with \`exp\` related functions?](https://discourse.julialang.org/t/how-to-do-high-precision-linear-algebra-with-exp-related-functions/122114)

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**Author:** [@singularitti](https://discourse.julialang.org/u/singularitti)\
**Replies:** 2\
**Last updated:** [November 1, 2024, 9:21am UTC](https://discourse.julialang.org/t/how-to-do-high-precision-linear-algebra-with-exp-related-functions/122114 "2024-11-01T09:21:18Z")

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Is there a library that supports exp, sin, cos, etc., on matrices with precisions higher than Float64? Here’s my test code: julia\> A = rand(BigFloat, 10, 10); julia\> exp(A) ERROR: MethodError: no method matching exp!(:…

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## [Troubleshooting allocations in SymbolicUtils code](https://discourse.julialang.org/t/troubleshooting-allocations-in-symbolicutils-code/122027)

<div class="topic-metadata">

**Author:** [@ctessum](https://discourse.julialang.org/u/ctessum)\
**Replies:** 2\
**Last updated:** [November 1, 2024, 8:57am UTC](https://discourse.julialang.org/t/troubleshooting-allocations-in-symbolicutils-code/122027 "2024-11-01T08:57:34Z")

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Hello! I have some a model here that is having some performance issues. I’ve included below a screenshot of a performance profile: As you can see, the majority of the time is being taken up by a macro expansion in S…

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## [Symbolically solving a system of equations... "Matrix is not square" error](https://discourse.julialang.org/t/symbolically-solving-a-system-of-equations-matrix-is-not-square-error/122093)

<div class="topic-metadata">

**Author:** [@Someguy](https://discourse.julialang.org/u/Someguy)\
**Replies:** 6\
**Last updated:** [November 1, 2024, 8:37am UTC](https://discourse.julialang.org/t/symbolically-solving-a-system-of-equations-matrix-is-not-square-error/122093 "2024-11-01T08:37:41Z")

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I’m trying to find Requ(ivalent) for a circuit in terms of the 5 resistors in the circuit. I’ve written out the equations for the circuit as follows: using Symbolics @variables i1 i2 i3 i4 i5 iIn; equ1= iIn ~ i1 + i4 e…

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## [Real-time input and plotting with ModelingToolkit](https://discourse.julialang.org/t/real-time-input-and-plotting-with-modelingtoolkit/120713)

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**Author:** [@cstjean](https://discourse.julialang.org/u/cstjean)\
**Replies:** 9\
**Last updated:** [November 1, 2024, 8:37am UTC](https://discourse.julialang.org/t/real-time-input-and-plotting-with-modelingtoolkit/120713 "2024-11-01T08:37:00Z")

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I’d like to have an MTK model like D(x) = k\*x, and plot the solution in real time (after 1 second, the plot shows the solution from t=0 to t=1, etc.) I’d like k to be supplied by a real-time interactive slider (so that …

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## [Constant propagation with a namedtuple with one field](https://discourse.julialang.org/t/constant-propagation-with-a-namedtuple-with-one-field/121887)

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**Author:** [@f.ij](https://discourse.julialang.org/u/f.ij)\
**Replies:** 6\
**Last updated:** [November 1, 2024, 8:03am UTC](https://discourse.julialang.org/t/constant-propagation-with-a-namedtuple-with-one-field/121887 "2024-11-01T08:03:30Z")

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I’m trying to use the type of a NamedTuple to statically compile some parts of functions. I’ve found some unexpected behavior that I don’t really understand: When I use a NamedTuple with only one field it doesn’t seem to…

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## [Incrementally creating docstrings](https://discourse.julialang.org/t/incrementally-creating-docstrings/122115)

<div class="topic-metadata">

**Author:** [@GHTaarn](https://discourse.julialang.org/u/GHTaarn)\
**Replies:** 0\
**Last updated:** [November 1, 2024, 7:56am UTC](https://discourse.julialang.org/t/incrementally-creating-docstrings/122115 "2024-11-01T07:56:35Z")

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I am in a situation where I would like to construct a docstring piece by piece rather than doing it in just one statement. I tried: module A varname = 0 @doc "Apple" varname @doc "$(@doc varname) Orange" varname end bu…

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