# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1245

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

**Page:** 1246

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## [mul!(::Matrix, ::Matrix, ::UpperTriangular) is really slow](https://discourse.julialang.org/t/mul-matrix-matrix-uppertriangular-is-really-slow/69368)

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**Author:** [@Luapulu](https://discourse.julialang.org/u/Luapulu)\
**Replies:** 4\
**Last updated:** [October 8, 2021, 6:57am UTC](https://discourse.julialang.org/t/mul-matrix-matrix-uppertriangular-is-really-slow/69368 "2021-10-08T06:57:25Z")

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There seem to be efficient methods to do mul!(out, ::UpperTriangular, ::Matrix) and mul!(out, ::LowerTriangular, ::Matrix). However, when you reverse the arguments and use mul!(out, ::Matrix, ::UpperTriangular) the perfo…

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## [Quantum optics - expansion of functions to composite bases](https://discourse.julialang.org/t/quantum-optics-expansion-of-functions-to-composite-bases/69413)

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**Author:** [@natan.granit](https://discourse.julialang.org/u/natan.granit)\
**Replies:** 0\
**Last updated:** [October 8, 2021, 6:29am UTC](https://discourse.julialang.org/t/quantum-optics-expansion-of-functions-to-composite-bases/69413 "2021-10-08T06:29:00Z")

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I’m using a composite fock basis in the Quantum optics pkg and I wanted to use the following functions: \[ QuantumOpticsBase.transform \] API · QuantumOptics.jl \[ QuantumOpticsBase.qfunc \] API · QuantumOptics.jl \[ Quan…

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## [Issues adding images to my package docs (built from Documenter.jl)](https://discourse.julialang.org/t/issues-adding-images-to-my-package-docs-built-from-documenter-jl/46480)

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**Author:** [@vlandau](https://discourse.julialang.org/u/vlandau)\
**Replies:** 5\
**Last updated:** [October 8, 2021, 6:20am UTC](https://discourse.julialang.org/t/issues-adding-images-to-my-package-docs-built-from-documenter-jl/46480 "2021-10-08T06:20:09Z")

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After a lot of trial and error I finally found out how to properly embed and render HTML code in .md files fed to Documenter.jl, but now I’m finding that the images aren’t showing up in a table I developed to place two i…

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## [PhD position in machine learning for education](https://discourse.julialang.org/t/phd-position-in-machine-learning-for-education/67741)

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**Author:** [@sethaxen](https://discourse.julialang.org/u/sethaxen)\
**Replies:** 4\
**Last updated:** [October 8, 2021, 5:46am UTC](https://discourse.julialang.org/t/phd-position-in-machine-learning-for-education/67741 "2021-10-08T05:46:46Z")

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Like learning math, bio, econ, etc but worried how fast you forget? We are offering a PhD position to fix that with ML algorithms, FOSS software, and cognitive testing at the Cluster of Excellence Machine Learning for Sc…

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## [Code slower than Rust equivalent](https://discourse.julialang.org/t/code-slower-than-rust-equivalent/69343)

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**Author:** [@fcharih](https://discourse.julialang.org/u/fcharih)\
**Replies:** 17\
**Last updated:** [October 8, 2021, 12:04am UTC](https://discourse.julialang.org/t/code-slower-than-rust-equivalent/69343 "2021-10-08T00:04:13Z")

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Hello, I am trying to port code from a Rust codebase (not my own code) to Julia. Even though the code is nearly identical to the Rust one, it appears to run ~10x slower. Code is not clean at all – I am just doing a “lit…

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## [ModelingToolkit: Index reduction and linear algebraic loops](https://discourse.julialang.org/t/modelingtoolkit-index-reduction-and-linear-algebraic-loops/69312)

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**Author:** [@AnHeuermann](https://discourse.julialang.org/u/AnHeuermann)\
**Replies:** 6\
**Last updated:** [October 7, 2021, 9:57pm UTC](https://discourse.julialang.org/t/modelingtoolkit-index-reduction-and-linear-algebraic-loops/69312 "2021-10-07T21:57:02Z")

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Hey all, I’m trying out ModelingToolkit.jl and want to investigate what is currently possible and what not and compare it to the OpenModelica Compiler Backend. Let’s say we have the following DAE: der(x) = y + a y = 3…

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## [Modify file after script starts](https://discourse.julialang.org/t/modify-file-after-script-starts/69373)

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**Author:** [@marllos](https://discourse.julialang.org/u/marllos)\
**Replies:** 4\
**Last updated:** [October 7, 2021, 9:16pm UTC](https://discourse.julialang.org/t/modify-file-after-script-starts/69373 "2021-10-07T21:16:10Z")

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Hello everyone. I would like some clarification. I run a script that uses several files and takes 24 h. After this script starts, can I modify the files and make other runs, without interfering with the first run? I do t…

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## [Distinguishing between unobserved parameters and control variables in DifferentialEquations](https://discourse.julialang.org/t/distinguishing-between-unobserved-parameters-and-control-variables-in-differentialequations/69142)

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**Author:** [@GregCoyle](https://discourse.julialang.org/u/GregCoyle)\
**Replies:** 6\
**Last updated:** [October 7, 2021, 8:38pm UTC](https://discourse.julialang.org/t/distinguishing-between-unobserved-parameters-and-control-variables-in-differentialequations/69142 "2021-10-07T20:38:11Z")

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Hello, I’m fresh off the boat to using Julia (coming from Python and Stan), and I am looking for the preferred generic solution to specifying an ODE with both unknown parameters and control variables/system forcings. As…

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## [Broadcasting - Mathematical notation](https://discourse.julialang.org/t/broadcasting-mathematical-notation/69327)

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**Author:** [@mthelm85](https://discourse.julialang.org/u/mthelm85)\
**Replies:** 12\
**Last updated:** [October 7, 2021, 4:28pm UTC](https://discourse.julialang.org/t/broadcasting-mathematical-notation/69327 "2021-10-07T16:28:12Z")

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What’s the proper notation for something like this? x = \[0.09, 0.2, 0.05 ,0.01\] w = \[0.81 0.92 0.86 0.32; 0.42 0.95 0.96 0.53\] b = \[0.57, 0.52\] f(x) = σ.(b + w \* x) f(x) = \\sigma.(b + wx) Is there a common notation th…

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## [What is the equivalent of vmin and vmax in Makie?](https://discourse.julialang.org/t/what-is-the-equivalent-of-vmin-and-vmax-in-makie/69387)

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**Author:** [@juliohm](https://discourse.julialang.org/u/juliohm)\
**Replies:** 1\
**Last updated:** [October 7, 2021, 7:50pm UTC](https://discourse.julialang.org/t/what-is-the-equivalent-of-vmin-and-vmax-in-makie/69387 "2021-10-07T19:50:23Z")

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In Plots.jl we can pass the keyword arguments vmin=0.0, vmax=1.0 in plot commands like heatmap to set the range of the colormap. Is there an equivalent in Makie?

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## [Newbie: Variables are missing from the variable map: PMSM model](https://discourse.julialang.org/t/newbie-variables-are-missing-from-the-variable-map-pmsm-model/69314)

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**Author:** [@gruemelmonster](https://discourse.julialang.org/u/gruemelmonster)\
**Replies:** 3\
**Last updated:** [October 7, 2021, 7:41pm UTC](https://discourse.julialang.org/t/newbie-variables-are-missing-from-the-variable-map-pmsm-model/69314 "2021-10-07T19:41:14Z")

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Based from the RC example I am trying to build something different to learn more about ModelingToolkit.jl. But I am struggling with an error message about “\[Ψd(t), Ψq(t), ω(t)\] are missing from the variable map” and I am…

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## [How to "freeze" parameters to functional objects?](https://discourse.julialang.org/t/how-to-freeze-parameters-to-functional-objects/69381)

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**Author:** [@jinml](https://discourse.julialang.org/u/jinml)\
**Replies:** 3\
**Last updated:** [October 7, 2021, 7:34pm UTC](https://discourse.julialang.org/t/how-to-freeze-parameters-to-functional-objects/69381 "2021-10-07T19:34:55Z")

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Hi, I am generating function objects depending on many parameters that must be computed through complicated equations. I am writing a for loop to compute many different collections of these parameters and finally genera…

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## [Problem with compat specification](https://discourse.julialang.org/t/problem-with-compat-specification/69386)

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**Author:** [@Johncowk](https://discourse.julialang.org/u/Johncowk)\
**Replies:** 0\
**Last updated:** [October 7, 2021, 6:58pm UTC](https://discourse.julialang.org/t/problem-with-compat-specification/69386 "2021-10-07T18:58:56Z")

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In order to adhere to the guidelines, I added compat entries the project.toml of my package, but for some reason that I can’t figure out, the package Plots.jl is creating me a lot of troubles. If I specify a version then…

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## [PlutoUI Buttons to push user input to a list](https://discourse.julialang.org/t/plutoui-buttons-to-push-user-input-to-a-list/69369)

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**Author:** [@dmoored4](https://discourse.julialang.org/u/dmoored4)\
**Replies:** 2\
**Last updated:** [October 7, 2021, 3:02pm UTC](https://discourse.julialang.org/t/plutoui-buttons-to-push-user-input-to-a-list/69369 "2021-10-07T15:02:09Z")

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I would like to append some user input to a list by using a Button to submit it. The problem is that every change in the user input results in a new submission, regardless of whether the submit button has been clicked. I…

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## [Loosing performance with \`Threads.@threads\` for loop](https://discourse.julialang.org/t/loosing-performance-with-threads-threads-for-loop/69358)

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**Author:** [@Kevin\_Kleinbeck](https://discourse.julialang.org/u/Kevin_Kleinbeck)\
**Replies:** 10\
**Last updated:** [October 7, 2021, 2:36pm UTC](https://discourse.julialang.org/t/loosing-performance-with-threads-threads-for-loop/69358 "2021-10-07T14:36:45Z")

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I have strange performance issues when I use Threads.@threads to parallelize a for-loop. My machine runs on 40 cores: julia\> Threads.nthreads() 40 Now, I lose performance even with a quite simple example: N = 500 m = …

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## [Makie - Camera position](https://discourse.julialang.org/t/makie-camera-position/69243)

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**Author:** [@Kang\_Pyo\_So](https://discourse.julialang.org/u/Kang_Pyo_So)\
**Replies:** 6\
**Last updated:** [October 7, 2021, 2:34pm UTC](https://discourse.julialang.org/t/makie-camera-position/69243 "2021-10-07T14:34:24Z")

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Hi Everyone, i have been using the Makie for a while. particularly, I like the 3D reconstruction function. the 3D reconstructive function allow me create the color code 3D plot from the 3D electron microscopy. however…

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## [Current state of Juno?](https://discourse.julialang.org/t/current-state-of-juno/60238)

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**Author:** [@pg261](https://discourse.julialang.org/u/pg261)\
**Replies:** 23\
**Last updated:** [October 7, 2021, 2:24pm UTC](https://discourse.julialang.org/t/current-state-of-juno/60238 "2021-10-07T14:24:09Z")

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Hi there, I’m quite new to Julia. I’ve tried Juno in the last couple of days – because it’s certainly well advertised on Julia’s main homepage. I absolutely love it! However, it says somewhere Attention : We have deci…

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## [Cumsum reversed?](https://discourse.julialang.org/t/cumsum-reversed/69355)

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**Author:** [@BLI](https://discourse.julialang.org/u/BLI)\
**Replies:** 6\
**Last updated:** [October 7, 2021, 2:23pm UTC](https://discourse.julialang.org/t/cumsum-reversed/69355 "2021-10-07T14:23:52Z")

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I need to do cumsum where I start at the end of vector v, and sum backwards. Is there a separate function for this, or should I just do cumsum(v\[end:-1:1\])\[end:-1:1\]?

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## [Missing \`deleteat!\` method for SparseVector](https://discourse.julialang.org/t/missing-deleteat-method-for-sparsevector/69370)

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**Author:** [@lrnv](https://discourse.julialang.org/u/lrnv)\
**Replies:** 8\
**Last updated:** [October 7, 2021, 2:17pm UTC](https://discourse.julialang.org/t/missing-deleteat-method-for-sparsevector/69370 "2021-10-07T14:17:06Z")

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Hey, I came across the following missing method: deleteat!(::SparseVector{Float64, Int64}, ::Int64) Indeed, julia\> x = sparse(\[0,1,0\]) 3-element SparseVector{Int64, Int64} with 1 stored entry: \[2\] = 1 julia\> del…

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## [Expressing the y-axis normally in semi-log plot](https://discourse.julialang.org/t/expressing-the-y-axis-normally-in-semi-log-plot/69371)

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**Author:** [@vinicius\_de\_lima](https://discourse.julialang.org/u/vinicius_de_lima)\
**Replies:** 1\
**Last updated:** [October 7, 2021, 1:52pm UTC](https://discourse.julialang.org/t/expressing-the-y-axis-normally-in-semi-log-plot/69371 "2021-10-07T13:52:43Z")

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I’m trying to express the numbers in the y-axis as 10,25,40 instead of in powers of 10, using the following code: using Plots w = \[19.0 ,24.8 ,28.5 ,33.2 ,35.3\] n\_golpes = \[35 ,28 ,22 ,19 ,16\] plot(w,n\_golpes, ylabel …

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## [Predator\_prey\_multiagent vs predator\_prey\_fast.jl example](https://discourse.julialang.org/t/predator-prey-multiagent-vs-predator-prey-fast-jl-example/69359)

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**Author:** [@Edu\_P](https://discourse.julialang.org/u/Edu_P)\
**Replies:** 4\
**Last updated:** [October 7, 2021, 1:34pm UTC](https://discourse.julialang.org/t/predator-prey-multiagent-vs-predator-prey-fast-jl-example/69359 "2021-10-07T13:34:00Z")

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Hello, in the predator\_prey\_multiagent.jl example I read the following comment: “This approach is less performant than the version in \[Predator-prey dynamics\]”. Has someone more details on what makes it a less performan…

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## [Why is AbstractString not a subtype of AbstractVector?](https://discourse.julialang.org/t/why-is-abstractstring-not-a-subtype-of-abstractvector/69189)

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**Author:** [@jonas-schulze](https://discourse.julialang.org/u/jonas-schulze)\
**Replies:** 10\
**Last updated:** [October 7, 2021, 1:28pm UTC](https://discourse.julialang.org/t/why-is-abstractstring-not-a-subtype-of-abstractvector/69189 "2021-10-07T13:28:28Z")

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While working on https://github.com/JuliaCollections/DataStructures.jl/pull/759, which I thought would be a funny solution to a project euler riddle, I noticed that String is not a subtype of AbstractVector{Char}. Are th…

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## [Preallocating Vector of Vectors](https://discourse.julialang.org/t/preallocating-vector-of-vectors/69304)

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**Author:** [@mrVeng](https://discourse.julialang.org/u/mrVeng)\
**Replies:** 25\
**Last updated:** [October 7, 2021, 12:38pm UTC](https://discourse.julialang.org/t/preallocating-vector-of-vectors/69304 "2021-10-07T12:38:14Z")

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Hi there, I have a project where I need to preallocate a Vector of Vectors. I could just use a multidimensional array, but this complicates things and makes the code less readable as well. Is there a way that I can prea…

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## [Parametric type of another parametric type](https://discourse.julialang.org/t/parametric-type-of-another-parametric-type/69258)

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**Author:** [@ismedina](https://discourse.julialang.org/u/ismedina)\
**Replies:** 11\
**Last updated:** [October 7, 2021, 12:21pm UTC](https://discourse.julialang.org/t/parametric-type-of-another-parametric-type/69258 "2021-10-07T12:21:58Z")

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TL;DR: how to define a parametric type where the parameter is another parametric type? I want to design some algorithms handling point clouds, where each point has some weight. I want to allow for general point clouds a…

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## [Projected coordinate system and multi-agents](https://discourse.julialang.org/t/projected-coordinate-system-and-multi-agents/69289)

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**Author:** [@Edu\_P](https://discourse.julialang.org/u/Edu_P)\
**Replies:** 2\
**Last updated:** [October 7, 2021, 11:21am UTC](https://discourse.julialang.org/t/projected-coordinate-system-and-multi-agents/69289 "2021-10-07T11:21:43Z")

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I’m a newbie to Julia agents.jl. How hard is to develop models in agents.jl requiring shape files and multi-agents using locations in a projected coordinate system? any experiences that can be compared to Gama Thanks

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## [DifferentialEquations -- transform time for all variables?](https://discourse.julialang.org/t/differentialequations-transform-time-for-all-variables/69356)

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**Author:** [@BLI](https://discourse.julialang.org/u/BLI)\
**Replies:** 1\
**Last updated:** [October 7, 2021, 11:12am UTC](https://discourse.julialang.org/t/differentialequations-transform-time-for-all-variables/69356 "2021-10-07T11:12:43Z")

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I have solved a matrix ODE with state u, and want to plot the solution sol. But I want to scale the time axis from second to year. Can I do this for all variables, something like: y2s = 365\*24\*60\*60 plot(sol,vars=((t,u)…

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## [Structural\_simplify fails if differential term is on the Right Hand Side of an equation](https://discourse.julialang.org/t/structural-simplify-fails-if-differential-term-is-on-the-right-hand-side-of-an-equation/69302)

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**Author:** [@SCher](https://discourse.julialang.org/u/SCher)\
**Replies:** 2\
**Last updated:** [October 7, 2021, 8:58am UTC](https://discourse.julialang.org/t/structural-simplify-fails-if-differential-term-is-on-the-right-hand-side-of-an-equation/69302 "2021-10-07T08:58:07Z")

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I am working on ModelingToolkit.jl using the RC circuit example at https://mtk.sciml.ai/stable/tutorials/acausal\_components/. It appears that as long as the Differential(t) terms in the equations are on the Left Hand Sid…

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## [DifferentialEquations: enforcing realistic solution?](https://discourse.julialang.org/t/differentialequations-enforcing-realistic-solution/69332)

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**Author:** [@BLI](https://discourse.julialang.org/u/BLI)\
**Replies:** 7\
**Last updated:** [October 7, 2021, 8:36am UTC](https://discourse.julialang.org/t/differentialequations-enforcing-realistic-solution/69332 "2021-10-07T08:36:03Z")

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I have a (large) ODE where each state x must lie in the range \[0,1\]. Due to numeric inaccuracies, the solution does drift outside of this range. I have tried to map x into the allowed range at the start of the function d…

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## [Displaying unitful dataframes](https://discourse.julialang.org/t/displaying-unitful-dataframes/69331)

<div class="topic-metadata">

**Author:** [@rafael.guerra](https://discourse.julialang.org/u/rafael.guerra)\
**Replies:** 3\
**Last updated:** [October 7, 2021, 8:12am UTC](https://discourse.julialang.org/t/displaying-unitful-dataframes/69331 "2021-10-07T08:12:21Z")

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What is the recommended procedure for displaying Unitful Dataframes? Example: using DataFrames, Unitful d = (0:10:1000)u"m" v = 1500u"m/s" .+ 1.5u"1/s"\*d t = \[0u"s"; cumsum(diff(d) ./ v\[1:end-1\])\] df = DataFrame(depth=…

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## [How to display \\bordermatrix in Documenter.jl](https://discourse.julialang.org/t/how-to-display-bordermatrix-in-documenter-jl/69345)

<div class="topic-metadata">

**Author:** [@hytonwons](https://discourse.julialang.org/u/hytonwons)\
**Replies:** 0\
**Last updated:** [October 7, 2021, 5:51am UTC](https://discourse.julialang.org/t/how-to-display-bordermatrix-in-documenter-jl/69345 "2021-10-07T05:51:47Z")

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Hi there, I was following LaTeX syntax in Documenter.jl when I need to display matrices with indices. Typically, we would use \\bordermatrix in LaTeX, however, it seems not to work in Documenter.jl. (I also turned to D…

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