# Latest

**URL:** https://discourse.julialang.org/latest.md?page=829

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

**Page:** 830

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## [A Unified Interface for Rootfinding](https://discourse.julialang.org/t/a-unified-interface-for-rootfinding/698)

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**Author:** [@ChrisRackauckas](https://discourse.julialang.org/u/ChrisRackauckas)\
**Replies:** 22\
**Last updated:** [December 24, 2022, 1:56pm UTC](https://discourse.julialang.org/t/a-unified-interface-for-rootfinding/698 "2022-12-24T13:56:23Z")

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One of the most useful developments of Julia is the concept of the metapackage. A package management system coupled with multiple dispatch has lead to ecosystems like Plots.jl, DiffEqBase.jl (DifferentialEquations.jl), a…

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## [In Gplots, draw PNG gplot applies incorrect edge label?](https://discourse.julialang.org/t/in-gplots-draw-png-gplot-applies-incorrect-edge-label/92033)

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**Author:** [@Colin\_Beckingham](https://discourse.julialang.org/u/Colin_Beckingham)\
**Replies:** 3\
**Last updated:** [December 23, 2022, 1:35pm UTC](https://discourse.julialang.org/t/in-gplots-draw-png-gplot-applies-incorrect-edge-label/92033 "2022-12-23T13:35:04Z")

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I’m experimenting with drawing PNG images of graphs. All is well except that when I attempt to use edge weights as edge labels, all the correct weight values appear in the image, but they are on the wrong edges. As I cr…

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## [Stack different color palettes in a single plot](https://discourse.julialang.org/t/stack-different-color-palettes-in-a-single-plot/92076)

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**Author:** [@Jose\_Diaz](https://discourse.julialang.org/u/Jose_Diaz)\
**Replies:** 1\
**Last updated:** [December 24, 2022, 12:02pm UTC](https://discourse.julialang.org/t/stack-different-color-palettes-in-a-single-plot/92076 "2022-12-24T12:02:54Z")

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Hello! Let’s say I have the following code. using Plots plots = palette.(\[:leonardo, :autumn\]) By doing that, I create a Vector{ColorPalette}, but actually I’d like to stack and display both color palettes (hopefully…

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## [Horizontal Slicing in Integral](https://discourse.julialang.org/t/horizontal-slicing-in-integral/92043)

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**Author:** [@Freya\_the\_Goddess](https://discourse.julialang.org/u/Freya_the_Goddess)\
**Replies:** 10\
**Last updated:** [December 24, 2022, 8:02am UTC](https://discourse.julialang.org/t/horizontal-slicing-in-integral/92043 "2022-12-24T08:02:39Z")

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Hi all, it is quite hard for me to understand for part (c) this is the question: I have worked on part (b): Basically just make integral from the interval \[1,c\] and find half the area of part (a) \\int\_{1}^{c} \\fra…

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## [OrdinaryDiffEq throws error when using sparse jacobian without specifying linear solver](https://discourse.julialang.org/t/ordinarydiffeq-throws-error-when-using-sparse-jacobian-without-specifying-linear-solver/89141)

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**Author:** [@parb](https://discourse.julialang.org/u/parb)\
**Replies:** 3\
**Last updated:** [December 24, 2022, 7:14am UTC](https://discourse.julialang.org/t/ordinarydiffeq-throws-error-when-using-sparse-jacobian-without-specifying-linear-solver/89141 "2022-12-24T07:14:49Z")

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Hi All, I nearly successfully created a sparse ODEProblem by using Symbolics.jacobian\_sparsity, but the solver throws an error unless I use TRBDF2(), (or one of the other linear solvers), coming from OrdinaryDiffEq (her…

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## [Discrepancy in DiffEqParamEstim](https://discourse.julialang.org/t/discrepancy-in-diffeqparamestim/86300)

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**Author:** [@affans](https://discourse.julialang.org/u/affans)\
**Replies:** 1\
**Last updated:** [December 24, 2022, 6:34am UTC](https://discourse.julialang.org/t/discrepancy-in-diffeqparamestim/86300 "2022-12-24T06:34:23Z")

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Before I open a bug report on the official repo, just want to make sure I am on the right path. Consider a simple 2 parameter estimation of an ODE. using DifferentialEquations using DiffEqParamEstim using Optim # some …

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## [Julia v1.8.4 has been released](https://discourse.julialang.org/t/julia-v1-8-4-has-been-released/92074)

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**Author:** [@ararslan](https://discourse.julialang.org/u/ararslan)\
**Replies:** 0\
**Last updated:** [December 24, 2022, 3:23am UTC](https://discourse.julialang.org/t/julia-v1-8-4-has-been-released/92074 "2022-12-24T03:23:21Z")

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The Julia developers are pleased to announce the release of v1.8.4, the fourth patch release in the 1.8 stable series. You can download binaries at https://julialang.org/downloads in the “current stable release” section.…

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## [Multivariable piecewise functions: Julia-basics help](https://discourse.julialang.org/t/multivariable-piecewise-functions-julia-basics-help/92070)

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**Author:** [@manya](https://discourse.julialang.org/u/manya)\
**Replies:** 2\
**Last updated:** [December 24, 2022, 1:35am UTC](https://discourse.julialang.org/t/multivariable-piecewise-functions-julia-basics-help/92070 "2022-12-24T01:35:35Z")

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Hi, I was wondering how to create a piecewise function of two variables r(x,y) = \\begin{cases} f(x,y) & d(x,y)\\geq 0 \\\\ g(x,y) & d(x,y)\<0\\end{cases} and use it to plot the coordinate pair (x',y')= (m(x,y), n(x,y)) on…

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## [AD Compatible Numerical Differentiation & Integration with Discrete Data](https://discourse.julialang.org/t/ad-compatible-numerical-differentiation-integration-with-discrete-data/92068)

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**Author:** [@ejmeitz](https://discourse.julialang.org/u/ejmeitz)\
**Replies:** 1\
**Last updated:** [December 24, 2022, 1:22am UTC](https://discourse.julialang.org/t/ad-compatible-numerical-differentiation-integration-with-discrete-data/92068 "2022-12-24T01:22:19Z")

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Hello, I’m trying to calculate some numerical derivatives & integrals from discrete data inside of a loss function. This loss function must be compatible with auto-differentiation to find the minimum. I’ve tried the Num…

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## [@generated functions aggressively disallowing lambdas (and accusations of impurity! how impious!)](https://discourse.julialang.org/t/generated-functions-aggressively-disallowing-lambdas-and-accusations-of-impurity-how-impious/92072)

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**Author:** [@uniment](https://discourse.julialang.org/u/uniment)\
**Replies:** 0\
**Last updated:** [December 24, 2022, 1:10am UTC](https://discourse.julialang.org/t/generated-functions-aggressively-disallowing-lambdas-and-accusations-of-impurity-how-impious/92072 "2022-12-24T01:10:36Z")

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This seems a bit aggressive: Code 1: julia\> @generated f(x) = :( map(i-\>i, x) ) f (generic function with 1 method) julia\> f((1,2,3)) ERROR: The function body AST defined by this @generated function is not pure. This l…

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## [Very long stack trace](https://discourse.julialang.org/t/very-long-stack-trace/92025)

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**Author:** [@erlebach](https://discourse.julialang.org/u/erlebach)\
**Replies:** 15\
**Last updated:** [December 23, 2022, 11:01pm UTC](https://discourse.julialang.org/t/very-long-stack-trace/92025 "2022-12-23T23:01:11Z")

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I am running a SciML type program called RUDE. The code generates an error, with a stack trace of almost 1000 lines long. I attach the trace herein. Perhaps somebody could give me sense of what the error is about? Perhap…

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## [How to speed up a slow optimization routine (slower than Python currently)](https://discourse.julialang.org/t/how-to-speed-up-a-slow-optimization-routine-slower-than-python-currently/92054)

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**Author:** [@ejmeitz](https://discourse.julialang.org/u/ejmeitz)\
**Replies:** 8\
**Last updated:** [December 23, 2022, 10:19pm UTC](https://discourse.julialang.org/t/how-to-speed-up-a-slow-optimization-routine-slower-than-python-currently/92054 "2022-12-23T22:19:58Z")

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Hello, I’ve been porting some code from Python to Julia and it runs much slower than in Python. I’ve copied the function which is slowest below. This function takes ~3-4 seconds which itself is not horrible but I need t…

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## [Missing source file for MultivariatePolynomials](https://discourse.julialang.org/t/missing-source-file-for-multivariatepolynomials/92064)

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**Author:** [@bernardofpc](https://discourse.julialang.org/u/bernardofpc)\
**Replies:** 0\
**Last updated:** [December 23, 2022, 9:13pm UTC](https://discourse.julialang.org/t/missing-source-file-for-multivariatepolynomials/92064 "2022-12-23T21:13:38Z")

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I tried to install DiffEqFlux on a machine which (unfortunately) was running out of disk space. The Pkg.add() command failed with “no space left on device”. I cleaned up, and tried again. It apparently succeeded, but …

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## [How to save solution of differential equation as dataframe](https://discourse.julialang.org/t/how-to-save-solution-of-differential-equation-as-dataframe/92057)

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**Author:** [@Luigi\_Marongiu](https://discourse.julialang.org/u/Luigi_Marongiu)\
**Replies:** 1\
**Last updated:** [December 23, 2022, 9:04pm UTC](https://discourse.julialang.org/t/how-to-save-solution-of-differential-equation-as-dataframe/92057 "2022-12-23T21:04:48Z")

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Hello, I have generated a solution of a differential equation using DifferentialEquations. I saved the solution in the object soln. Is it possible to save it as a tab-delimited file (or csv) so I can open it again as a …

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## [ModelingToolkit variable metadata for connectors](https://discourse.julialang.org/t/modelingtoolkit-variable-metadata-for-connectors/92056)

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**Author:** [@xlxs4](https://discourse.julialang.org/u/xlxs4)\
**Replies:** 2\
**Last updated:** [December 23, 2022, 9:04pm UTC](https://discourse.julialang.org/t/modelingtoolkit-variable-metadata-for-connectors/92056 "2022-12-23T21:04:03Z")

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Hi! In the MTK documentation, specifically page Contextual Variable Types · ModelingToolkit.jl (sciml.ai) it reads: In many engineering systems some variables act like “flows” while others do not. For example, in circu…

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## [Mass matrix DAEs](https://discourse.julialang.org/t/mass-matrix-daes/6805)

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**Author:** [@FHell](https://discourse.julialang.org/u/FHell)\
**Replies:** 6\
**Last updated:** [December 23, 2022, 8:59pm UTC](https://discourse.julialang.org/t/mass-matrix-daes/6805 "2022-12-23T20:59:16Z")

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Hi, I am trying to run some DAE simulations using DifferentialEquations.jl, and am having some trouble. I am doing a very simple test function: function f!(t, u, du) du\[1\] = u\[2\] du\[2\] = u\[2\] - 1. return end…

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## [Reading video stream from IP camera](https://discourse.julialang.org/t/reading-video-stream-from-ip-camera/43782)

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**Author:** [@adriano.vilela](https://discourse.julialang.org/u/adriano.vilela)\
**Replies:** 3\
**Last updated:** [December 23, 2022, 6:41pm UTC](https://discourse.julialang.org/t/reading-video-stream-from-ip-camera/43782 "2022-12-23T18:41:52Z")

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I’m working on a project where I need to read an Internet video stream. I have the URL needed to connect to the IP camera. The camera administrator tells me that I can use either HTTP or RTSP (Real Time Streaming Protoco…

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## [Run multiple instances of transform on specific column combinations of a GroupedDataFrame in DataFrames mini language](https://discourse.julialang.org/t/run-multiple-instances-of-transform-on-specific-column-combinations-of-a-groupeddataframe-in-dataframes-mini-language/91736)

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**Author:** [@phantom](https://discourse.julialang.org/u/phantom)\
**Replies:** 22\
**Last updated:** [December 23, 2022, 5:32pm UTC](https://discourse.julialang.org/t/run-multiple-instances-of-transform-on-specific-column-combinations-of-a-groupeddataframe-in-dataframes-mini-language/91736 "2022-12-23T17:32:03Z")

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I’m probably missing something very basic in the syntax but if I have a GroupedDataFrame with n columns. (I’ll set n = 4 to illustrate the issue but for the actual use case suppose n \>\> 4) gdf = groupby(DataFrame(id=1:…

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## [Incorrect lyapunov spectrum DynamicalSystems.jl](https://discourse.julialang.org/t/incorrect-lyapunov-spectrum-dynamicalsystems-jl/91998)

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**Author:** [@Sergey\_Novak](https://discourse.julialang.org/u/Sergey_Novak)\
**Replies:** 11\
**Last updated:** [December 23, 2022, 4:48pm UTC](https://discourse.julialang.org/t/incorrect-lyapunov-spectrum-dynamicalsystems-jl/91998 "2022-12-23T16:48:52Z")

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I calculate lyapunov spectrum and it don’t have zero exponent. How i can it fix? I tried change intregrator from RK4 on Tsit5 and Vern9 and it don’t help. Also increase time of integrate don’t help function model(u, p …

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## [Difficulty with utilizing PowerModels.update data! function](https://discourse.julialang.org/t/difficulty-with-utilizing-powermodels-update-data-function/91906)

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**Author:** [@Wahee01](https://discourse.julialang.org/u/Wahee01)\
**Replies:** 5\
**Last updated:** [December 23, 2022, 4:25pm UTC](https://discourse.julialang.org/t/difficulty-with-utilizing-powermodels-update-data-function/91906 "2022-12-23T16:25:03Z")

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Hello to everyone. I apologize if my inquiry is too simple. Julia is a programming language that I am learning. For optimal power flow and power flow problems, I use the PowerModels toolkit. PowerModels.update data! is a…

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## [Indexing a DataFrame Index](https://discourse.julialang.org/t/indexing-a-dataframe-index/92030)

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**Author:** [@wiseac](https://discourse.julialang.org/u/wiseac)\
**Replies:** 12\
**Last updated:** [December 23, 2022, 4:08pm UTC](https://discourse.julialang.org/t/indexing-a-dataframe-index/92030 "2022-12-23T16:08:23Z")

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Hello, I am trying to write a function that takes in a DataFrame that has an index, df\[x:x2,c\], and uses those index numbers for calculations. An example would taking df\[1:100,1\] and then multiplying 1 and 100 by 2. Wh…

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## [StableRNG in Turing is not producing reproducible output](https://discourse.julialang.org/t/stablerng-in-turing-is-not-producing-reproducible-output/92032)

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**Author:** [@Sourish](https://discourse.julialang.org/u/Sourish)\
**Replies:** 12\
**Last updated:** [December 23, 2022, 3:45pm UTC](https://discourse.julialang.org/t/stablerng-in-turing-is-not-producing-reproducible-output/92032 "2022-12-23T15:45:36Z")

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Hi All: In the following code, we are using StableRNGs. However, the results are not reproducing. Can anybody help us? So that we can reproduce the results. using Turing, StableRNGs @model function example(x) m ~ …

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## [Constraints tolerance IPNewton in Optim.jl](https://discourse.julialang.org/t/constraints-tolerance-ipnewton-in-optim-jl/92038)

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**Author:** [@shce](https://discourse.julialang.org/u/shce)\
**Replies:** 0\
**Last updated:** [December 23, 2022, 8:56am UTC](https://discourse.julialang.org/t/constraints-tolerance-ipnewton-in-optim-jl/92038 "2022-12-23T08:56:01Z")

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Hello, I was wondering if it is possible to specify up to which tolerance the equality constraints are satisfied in Optim.jl using IPNewton method. Currently, the optimization stops because x\_tol or f\_tol are satisfied…

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## [Automatically naming N similar elements in MTK](https://discourse.julialang.org/t/automatically-naming-n-similar-elements-in-mtk/91888)

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**Author:** [@dodoplus](https://discourse.julialang.org/u/dodoplus)\
**Replies:** 5\
**Last updated:** [December 23, 2022, 11:41am UTC](https://discourse.julialang.org/t/automatically-naming-n-similar-elements-in-mtk/91888 "2022-12-23T11:41:24Z")

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Hi, I’d like a simple way of creating a “vector” of similar elements. I.e. I’d like: @named R = \[Resistor(R=n) for n in 1:10\] to create a vector of Resistors with resistances 1 to 10. These could be named e.g. R\_1…R\_…

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## [Custom array with padding through a view](https://discourse.julialang.org/t/custom-array-with-padding-through-a-view/91914)

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**Author:** [@mkoculak](https://discourse.julialang.org/u/mkoculak)\
**Replies:** 5\
**Last updated:** [December 23, 2022, 10:27am UTC](https://discourse.julialang.org/t/custom-array-with-padding-through-a-view/91914 "2022-12-23T10:27:50Z")

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I would like to pad my vector/array for doing FFT stuff, specifically mirroring - and since my data is pretty big, would be great if there was no need for extra allocations. My thought was to have a custom array type, t…

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## [Constraint set with max function](https://discourse.julialang.org/t/constraint-set-with-max-function/91997)

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**Author:** [@baprata](https://discourse.julialang.org/u/baprata)\
**Replies:** 2\
**Last updated:** [December 23, 2022, 9:59am UTC](https://discourse.julialang.org/t/constraint-set-with-max-function/91997 "2022-12-23T09:59:13Z")

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Concerning the constraint set I am having problem with the last term of the constraint (?): @constraint(model, \[m in 1:machines, j in 1:jobs\], PT\[m,j\] == SET\[m\] \* Z\[m,j\] + VT\[m\]\*(sum(v\[i\] \* X\[m,j,i\] for i in 1:parts)…

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## [NamedArray specifying only dimension names](https://discourse.julialang.org/t/namedarray-specifying-only-dimension-names/77895)

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**Author:** [@jar1](https://discourse.julialang.org/u/jar1)\
**Replies:** 3\
**Last updated:** [December 23, 2022, 6:16am UTC](https://discourse.julialang.org/t/namedarray-specifying-only-dimension-names/77895 "2022-12-23T06:16:28Z")

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In NamedArrays, is it possible to specify ("Rows", "Cols") but leaving the row and column numbers as 1,2,…? julia\> NamedArray(\[1 3; 2 4\], ( OrderedDict("A"=\>1, "B"=\>2), OrderedDict("C"=\>1, "D"=\>2) ), ("Rows", "Cols") ) …

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## [Compiling a Julia script into a single executable](https://discourse.julialang.org/t/compiling-a-julia-script-into-a-single-executable/92034)

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**Author:** [@Dreycen\_Foiles](https://discourse.julialang.org/u/Dreycen_Foiles)\
**Replies:** 0\
**Last updated:** [December 23, 2022, 6:48am UTC](https://discourse.julialang.org/t/compiling-a-julia-script-into-a-single-executable/92034 "2022-12-23T06:48:41Z")

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I’m trying to use PackageCompiler to compile a simple script of mine into a standalone application. Following the documentation on app creation, I created a folder consisting of all the compiled binaries. This is not ide…

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## [\[ANN\] CellularPotts.jl: MultiScale Modeling of BIological Cells](https://discourse.julialang.org/t/ann-cellularpotts-jl-multiscale-modeling-of-biological-cells/92029)

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**Author:** [@RobertGregg](https://discourse.julialang.org/u/RobertGregg)\
**Replies:** 0\
**Last updated:** [December 23, 2022, 1:09am UTC](https://discourse.julialang.org/t/ann-cellularpotts-jl-multiscale-modeling-of-biological-cells/92029 "2022-12-23T01:09:55Z")

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Hi everyone, I want to introduce a package I’ve been working on for a while now called CellularPotts.jl (Here is the Github repo and the documention). The point of this package is to model cell behaviors like adhesion, …

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## [Can't we create a macro named "?"](https://discourse.julialang.org/t/cant-we-create-a-macro-named/92027)

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**Author:** [@joa-quim](https://discourse.julialang.org/u/joa-quim)\
**Replies:** 2\
**Last updated:** [December 22, 2022, 11:41pm UTC](https://discourse.julialang.org/t/cant-we-create-a-macro-named/92027 "2022-12-22T23:41:47Z")

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julia\> @? meca ┌ Error: Failed to revise C:\\Users\\joaqu\\.julia\\dev\\GMT\\src\\common\_options.jl │ exception = │ LoadError: "invalid identifier name \\"?\\"" But we have the broadcast macro @. (which I can’t find the def…

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