# Latest

**URL:** https://discourse.julialang.org/latest.md?page=782

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

**Page:** 783

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## [Using Split ODE Solvers within Method of Steps](https://discourse.julialang.org/t/using-split-ode-solvers-within-method-of-steps/94569)

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**Author:** [@wpowell96](https://discourse.julialang.org/u/wpowell96)\
**Replies:** 2\
**Last updated:** [February 13, 2023, 5:39pm UTC](https://discourse.julialang.org/t/using-split-ode-solvers-within-method-of-steps/94569 "2023-02-13T17:39:21Z")

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I am interesting in simulating delayed reaction-diffusion equations of the form u\_t = \\Delta u + f(u,u(t-\\tau)) in a 2-D spatial domain of modest size (10,000 equations) and a non-stiff nonlinearity (for now). My curre…

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## [\[ANN\] SPDX.jl v0.2.0: Reading and Writing SPDX Files - Now with support for v2.3 of the specification](https://discourse.julialang.org/t/ann-spdx-jl-v0-2-0-reading-and-writing-spdx-files-now-with-support-for-v2-3-of-the-specification/94576)

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**Author:** [@SamuraiAku](https://discourse.julialang.org/u/SamuraiAku)\
**Replies:** 0\
**Last updated:** [February 13, 2023, 5:08pm UTC](https://discourse.julialang.org/t/ann-spdx-jl-v0-2-0-reading-and-writing-spdx-files-now-with-support-for-v2-3-of-the-specification/94576 "2023-02-13T17:08:13Z")

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SPDX.jl A package for reading and writing SPDX files in Julia. Software Package Data eXchange (SPDX) is an open standard for communicating software bill of material information, including provenance, license, security, …

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## [QHack has started](https://discourse.julialang.org/t/qhack-has-started/94574)

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**Author:** [@kslimes](https://discourse.julialang.org/u/kslimes)\
**Replies:** 0\
**Last updated:** [February 13, 2023, 4:22pm UTC](https://discourse.julialang.org/t/qhack-has-started/94574 "2023-02-13T16:22:05Z")

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Read the introductory blog post here! QHack is a free event running from February 13-28 2023, featuring scientific talks and a hackathon with multiple challenges. You can still sign up (for free!) to participate and it’…

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## [Is it safe declare lock as module constant?](https://discourse.julialang.org/t/is-it-safe-declare-lock-as-module-constant/94507)

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**Author:** [@harsh\_kumar](https://discourse.julialang.org/u/harsh_kumar)\
**Replies:** 3\
**Last updated:** [February 13, 2023, 4:03pm UTC](https://discourse.julialang.org/t/is-it-safe-declare-lock-as-module-constant/94507 "2023-02-13T16:03:18Z")

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I have created a package that uses a spin lock and I have declared this as module constant (example shown below). Since Julia compiles the package, it will declare the constant only once. Will this cause any unexpected i…

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## [MethodOfLines & default vs. WENO scheme](https://discourse.julialang.org/t/methodoflines-default-vs-weno-scheme/94566)

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**Author:** [@BLI](https://discourse.julialang.org/u/BLI)\
**Replies:** 1\
**Last updated:** [February 13, 2023, 3:43pm UTC](https://discourse.julialang.org/t/methodoflines-default-vs-weno-scheme/94566 "2023-02-13T15:43:33Z")

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OK – I solved a “stupid” gas pipe example with manual semi-discretization + ModelingToolkit and lots of help from @baggepinnen, “MTK & vector equations…”. Now, I have figured out the basic solution of the problem using…

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## [Native eigenvals for differentiable programming](https://discourse.julialang.org/t/native-eigenvals-for-differentiable-programming/27126)

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**Author:** [@GJBoth](https://discourse.julialang.org/u/GJBoth)\
**Replies:** 23\
**Last updated:** [February 13, 2023, 3:32pm UTC](https://discourse.julialang.org/t/native-eigenvals-for-differentiable-programming/27126 "2023-02-13T15:32:20Z")

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Hi all, I’m working on a problem where I require an autodifferentiable eigenvalue solver for real, square matrices (but non-hermitian). Since Linear algebra’s version is based on LAPACK, I can’t use autodiff and I haven…

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## [The naming of \`allunique\` in DataFrames.jl](https://discourse.julialang.org/t/the-naming-of-allunique-in-dataframes-jl/94568)

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**Author:** [@alfaromartino](https://discourse.julialang.org/u/alfaromartino)\
**Replies:** 3\
**Last updated:** [February 12, 2023, 9:27am UTC](https://discourse.julialang.org/t/the-naming-of-allunique-in-dataframes-jl/94568 "2023-02-12T09:27:21Z")

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Although it’s probably too late, a name like uniquerows would be more self-explanatory than allunique. Thanks for your excellent work!

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## [Multidimensional arrays as indices in setindex!: bug or feature?](https://discourse.julialang.org/t/multidimensional-arrays-as-indices-in-setindex-bug-or-feature/94558)

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**Author:** [@Az9DBvyVLWBjs8g](https://discourse.julialang.org/u/Az9DBvyVLWBjs8g)\
**Replies:** 1\
**Last updated:** [February 13, 2023, 2:29pm UTC](https://discourse.julialang.org/t/multidimensional-arrays-as-indices-in-setindex-bug-or-feature/94558 "2023-02-13T14:29:56Z")

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Hello everyone, I just found that one can use multidimensional arrays as indices within setindex!. They behave as 1d arrays, which is different from their behavior in getindex, thus the following assertion from the docs …

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## [Multiple connected scripts BUT all sharing the same dependancies how do I set up the project?](https://discourse.julialang.org/t/multiple-connected-scripts-but-all-sharing-the-same-dependancies-how-do-i-set-up-the-project/94522)

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**Author:** [@1153dent](https://discourse.julialang.org/u/1153dent)\
**Replies:** 9\
**Last updated:** [February 13, 2023, 2:17pm UTC](https://discourse.julialang.org/t/multiple-connected-scripts-but-all-sharing-the-same-dependancies-how-do-i-set-up-the-project/94522 "2023-02-13T14:17:28Z")

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I can’t get my head around how to set up the project so it handles this case. EITHER it’s so simple ( just putting the scripts in the src folder) or it’s not wise to do so? and put them in 3 separate projects I have thr…

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## [Not able to run Julia through python on a server in a frontend type application](https://discourse.julialang.org/t/not-able-to-run-julia-through-python-on-a-server-in-a-frontend-type-application/89431)

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**Author:** [@shwetank\_verma](https://discourse.julialang.org/u/shwetank_verma)\
**Replies:** 3\
**Last updated:** [February 13, 2023, 2:04pm UTC](https://discourse.julialang.org/t/not-able-to-run-julia-through-python-on-a-server-in-a-frontend-type-application/89431 "2023-02-13T14:04:35Z")

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Hey everyone, I am not able to find anything on this so I will try to explain as many things as I can. We are building a cloud-based simulation application whose frontend is Javascript which is calling python script. T…

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## [How to initialize array of arrays with specific type?](https://discourse.julialang.org/t/how-to-initialize-array-of-arrays-with-specific-type/94557)

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**Author:** [@CeterisPartybus](https://discourse.julialang.org/u/CeterisPartybus)\
**Replies:** 7\
**Last updated:** [February 13, 2023, 1:46pm UTC](https://discourse.julialang.org/t/how-to-initialize-array-of-arrays-with-specific-type/94557 "2023-02-13T13:46:26Z")

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Hi everyone, I would like to initialize an array that is later filled with interpolation objects. To be specific, it should store output from interpolate() from Interpolations.jl later on. Normally, I can initialize an…

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## [Data structure for convenient access to tabular data](https://discourse.julialang.org/t/data-structure-for-convenient-access-to-tabular-data/94523)

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**Author:** [@bbrunaud](https://discourse.julialang.org/u/bbrunaud)\
**Replies:** 5\
**Last updated:** [February 13, 2023, 1:26pm UTC](https://discourse.julialang.org/t/data-structure-for-convenient-access-to-tabular-data/94523 "2023-02-13T13:26:18Z")

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Hello community I use Julia to build JuMP models. What you usually have is indexed parameters that I would like to store in DataFrames and have convenient access when writing models. Think of a DataFrame where you have …

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## [Using Plots, is there a simple way to plot a 3D cube/rectangle?](https://discourse.julialang.org/t/using-plots-is-there-a-simple-way-to-plot-a-3d-cube-rectangle/94528)

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**Author:** [@Ahmed\_Salih](https://discourse.julialang.org/u/Ahmed_Salih)\
**Replies:** 1\
**Last updated:** [February 12, 2023, 6:49pm UTC](https://discourse.julialang.org/t/using-plots-is-there-a-simple-way-to-plot-a-3d-cube-rectangle/94528 "2023-02-12T18:49:19Z")

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Hello! I found this nice function online: rectangle(w, h, x, y) = Shape(x .+ \[0,w,w,0\], y .+ \[0,0,h,h\]) Which can produce: x = y = 1 w = h = 1 plot(rectangle(w, h, x, y)) Does anyone know how to produce a 3d equi…

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## [ProgressiveHedging.jl - Decision Variables](https://discourse.julialang.org/t/progressivehedging-jl-decision-variables/94414)

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**Author:** [@Mariana](https://discourse.julialang.org/u/Mariana)\
**Replies:** 2\
**Last updated:** [February 13, 2023, 1:22pm UTC](https://discourse.julialang.org/t/progressivehedging-jl-decision-variables/94414 "2023-02-13T13:22:48Z")

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Hello! I’m starting to use ProgressiveHedging.jl and testing it in a two-stage problem. However, both the first and second stages variables in my case present different dimensions. For example, I have 6 first-stage dec…

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## [GLMakie: Reset all sliders inside SliderGrid via Button](https://discourse.julialang.org/t/glmakie-reset-all-sliders-inside-slidergrid-via-button/94555)

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**Author:** [@ellocco](https://discourse.julialang.org/u/ellocco)\
**Replies:** 0\
**Last updated:** [February 13, 2023, 12:35pm UTC](https://discourse.julialang.org/t/glmakie-reset-all-sliders-inside-slidergrid-via-button/94555 "2023-02-13T12:35:45Z")

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I wonder, if something exist like “Mouse.DoubleClick” on SliderGrid? The code below does what it should do, but it uses a for-loop over the SliderGrid. using GLMakie fig = Figure() # --- figure set-up: two panes side …

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## [From Scmil\_train to Optimization.jl](https://discourse.julialang.org/t/from-scmil-train-to-optimization-jl/94316)

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**Author:** [@qjulia](https://discourse.julialang.org/u/qjulia)\
**Replies:** 26\
**Last updated:** [February 13, 2023, 12:07pm UTC](https://discourse.julialang.org/t/from-scmil-train-to-optimization-jl/94316 "2023-02-13T12:07:23Z")

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Hello, I am trying to write the following line: optimized\_sol\_nn = DiffEqFlux.sciml\_train(p -\> cost\_adjoint\_nn(p, 0.08), θ\_nn,RADAM(0.003), maxiters = 1000) with Optimization.jl package since scmil\_train is deprecated…

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## [Enabling broadcasting for named tuples alt. broadcast? broadcasted? broadcastable? BroadcastStyle?](https://discourse.julialang.org/t/enabling-broadcasting-for-named-tuples-alt-broadcast-broadcasted-broadcastable-broadcaststyle/94468)

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**Author:** [@Euhan](https://discourse.julialang.org/u/Euhan)\
**Replies:** 1\
**Last updated:** [February 13, 2023, 11:59am UTC](https://discourse.julialang.org/t/enabling-broadcasting-for-named-tuples-alt-broadcast-broadcasted-broadcastable-broadcaststyle/94468 "2023-02-13T11:59:44Z")

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Like many before me (if my googling serves me right), I found myself in need of broadcasting over named tuples. In this case it is in the hope that I can get MLUtils.jl to handle batches that are (you guessed it) named t…

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## [The heat equation solution use MethodOfLines.jl](https://discourse.julialang.org/t/the-heat-equation-solution-use-methodoflines-jl/94331)

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**Author:** [@Fred\_He](https://discourse.julialang.org/u/Fred_He)\
**Replies:** 12\
**Last updated:** [February 13, 2023, 11:31am UTC](https://discourse.julialang.org/t/the-heat-equation-solution-use-methodoflines-jl/94331 "2023-02-13T11:31:56Z")

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the solution looks weird in https://docs.sciml.ai/MethodOfLines/stable/tutorials/heatss/ why its u(1, 1) = 0?

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## [Struggling to migrate from R (dplyr) to Julia (DataFrameMeta)](https://discourse.julialang.org/t/struggling-to-migrate-from-r-dplyr-to-julia-dataframemeta/94473)

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**Author:** [@Philip\_Rhome](https://discourse.julialang.org/u/Philip_Rhome)\
**Replies:** 10\
**Last updated:** [February 13, 2023, 11:16am UTC](https://discourse.julialang.org/t/struggling-to-migrate-from-r-dplyr-to-julia-dataframemeta/94473 "2023-02-13T11:16:32Z")

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hello dear julia developers i’m new to julia and i’m fascinated by the power and performance of this great language i’m trying to convert my notebooks in R to Julia to help me learn it but the issue is that i’m stuck w…

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## [Best way to write dense rank-one update?](https://discourse.julialang.org/t/best-way-to-write-dense-rank-one-update/3929)

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**Author:** [@Stephen\_Vavasis](https://discourse.julialang.org/u/Stephen_Vavasis)\
**Replies:** 9\
**Last updated:** [February 13, 2023, 10:38am UTC](https://discourse.julialang.org/t/best-way-to-write-dense-rank-one-update/3929 "2023-02-13T10:38:36Z")

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For a rank-one update of a dense matrix in Matlab, I would write A=A+u\*v'. If I just use the same Matlab statement in Julia, I’ll get poor performance because of needless memory allocation and copying. I know how to wr…

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## [How to test if package is installed](https://discourse.julialang.org/t/how-to-test-if-package-is-installed/3508)

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**Author:** [@Tamas\_Papp](https://discourse.julialang.org/u/Tamas_Papp)\
**Replies:** 23\
**Last updated:** [February 13, 2023, 10:00am UTC](https://discourse.julialang.org/t/how-to-test-if-package-is-installed/3508 "2023-02-13T10:00:07Z")

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What’s the recommended API for testing if a package (which may not be registed) is installed? I have seen two versions floating around: "somepackage" ∈ keys(Pkg.installed()) and isdir(Pkg.dir("somepackage")) The seco…

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## [AbstractMissing](https://discourse.julialang.org/t/abstractmissing/94413)

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**Author:** [@croberts](https://discourse.julialang.org/u/croberts)\
**Replies:** 7\
**Last updated:** [February 13, 2023, 8:55am UTC](https://discourse.julialang.org/t/abstractmissing/94413 "2023-02-13T08:55:29Z")

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I love Julia but am often puzzled about why Base does not make use of some of the things that make Julia great. In base, the definition of missing is: struct Missing end const missing = Missing() methods operating o…

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## [Proper way to identify variables/models with functions](https://discourse.julialang.org/t/proper-way-to-identify-variables-models-with-functions/94535)

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**Author:** [@PaterPen](https://discourse.julialang.org/u/PaterPen)\
**Replies:** 1\
**Last updated:** [February 13, 2023, 8:03am UTC](https://discourse.julialang.org/t/proper-way-to-identify-variables-models-with-functions/94535 "2023-02-13T08:03:37Z")

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Recently I revisited some old Julia code of mine and wondered how to implement it properly. The setting is: I have a model struct which holds some model definition. Let’s say, each model just describes some system of eq…

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## [Printing zero elements in lines of a sparse matrix](https://discourse.julialang.org/t/printing-zero-elements-in-lines-of-a-sparse-matrix/94530)

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**Author:** [@Gravlax](https://discourse.julialang.org/u/Gravlax)\
**Replies:** 6\
**Last updated:** [February 13, 2023, 7:55am UTC](https://discourse.julialang.org/t/printing-zero-elements-in-lines-of-a-sparse-matrix/94530 "2023-02-13T07:55:43Z")

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Dear all, I would like to print the non-zero elements along a give line of a sparse matrix. In fact I’m trying to find a way to reproduce the behaviour of MATLAB. For example, here’s how a line is printed in MATLAB, it…

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## [Integration of arbitrarily-spaced data](https://discourse.julialang.org/t/integration-of-arbitrarily-spaced-data/94533)

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**Author:** [@SantiagoOrtiz](https://discourse.julialang.org/u/SantiagoOrtiz)\
**Replies:** 2\
**Last updated:** [February 13, 2023, 7:25am UTC](https://discourse.julialang.org/t/integration-of-arbitrarily-spaced-data/94533 "2023-02-13T07:25:22Z")

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Hello all, Is there any function/package in Julia that I could use to integrate one-dimensional arbitrarily-spaced data? NumericalIntegration has several options, but they require evenly spaced data. Best, Santiago

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## [Unexpected result from short-circuiting (inline if)](https://discourse.julialang.org/t/unexpected-result-from-short-circuiting-inline-if/94400)

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**Author:** [@CarlosST](https://discourse.julialang.org/u/CarlosST)\
**Replies:** 9\
**Last updated:** [February 13, 2023, 5:01am UTC](https://discourse.julialang.org/t/unexpected-result-from-short-circuiting-inline-if/94400 "2023-02-13T05:01:09Z")

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I’m quite familiar with using short-circuit evaluation as an inline if, and my understanding was that writing cond && (expression) is exactly identical to the more traditional: if cond expression; end However, I fo…

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## [Why can't the compiler constant-fold operations on BigInt and BigFloat?](https://discourse.julialang.org/t/why-cant-the-compiler-constant-fold-operations-on-bigint-and-bigfloat/94447)

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**Author:** [@bobcassels](https://discourse.julialang.org/u/bobcassels)\
**Replies:** 14\
**Last updated:** [February 13, 2023, 1:44am UTC](https://discourse.julialang.org/t/why-cant-the-compiler-constant-fold-operations-on-bigint-and-bigfloat/94447 "2023-02-13T01:44:49Z")

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wtf(x) = x \* Float64(big(12.34) / big(180)^3) @code\_llvm wtf(1.0) shows runtime calls to do the big-ifying, and the exponentiation. If I remove the calls to big, it constant-folds just fine.

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## [Compile C code with Julia package](https://discourse.julialang.org/t/compile-c-code-with-julia-package/91305)

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**Author:** [@PaterPen](https://discourse.julialang.org/u/PaterPen)\
**Replies:** 8\
**Last updated:** [February 13, 2023, 1:02am UTC](https://discourse.julialang.org/t/compile-c-code-with-julia-package/91305 "2023-02-13T01:02:32Z")

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Hi, I am currently thinking about migrating an R package with underlying C/C++ code to a Julia package. However, in the short term the large C/C++ codebase should be reused and therefore is intended to be called from wi…

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## [Documenting packages](https://discourse.julialang.org/t/documenting-packages/94493)

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**Author:** [@dscolby](https://discourse.julialang.org/u/dscolby)\
**Replies:** 8\
**Last updated:** [February 13, 2023, 12:14am UTC](https://discourse.julialang.org/t/documenting-packages/94493 "2023-02-13T00:14:59Z")

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I just created a new package but I’m having a lot of trouble getting the documentation to render with Documenter.jl. When I deploy it to GitHub pages it displays the readme instead of the index.md file in my docs/src dir…

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## [Using interpolation with unit verification in ModelingToolkit](https://discourse.julialang.org/t/using-interpolation-with-unit-verification-in-modelingtoolkit/93837)

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**Author:** [@contradict](https://discourse.julialang.org/u/contradict)\
**Replies:** 1\
**Last updated:** [February 12, 2023, 10:46pm UTC](https://discourse.julialang.org/t/using-interpolation-with-unit-verification-in-modelingtoolkit/93837 "2023-02-12T22:46:59Z")

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I am trying to build a simulation driven by tabulated data and use unit validation. This requires interpolation of the table, and it seems DataInterpolation.jl is the intended tool (Interpolations.jl could work, but I th…

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