# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=374

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

**Page:** 375

---

## [How to bring differential equations to wanted value with DiffEqFlux?](https://discourse.julialang.org/t/how-to-bring-differential-equations-to-wanted-value-with-diffeqflux/54167)

<div class="topic-metadata">

**Author:** [@Luigi\_Marongiu](https://discourse.julialang.org/u/Luigi_Marongiu)\
**Replies:** 24\
**Last updated:** [April 17, 2021, 11:13am UTC](https://discourse.julialang.org/t/how-to-bring-differential-equations-to-wanted-value-with-diffeqflux/54167 "2021-04-17T11:13:38Z")

</div>

Hello, I have a population system (bacteria/phages) that I have described with these ODEs that include the logistic factor: function sir!(du, u, p, t) # SIRl with logistic term μ, κ, φ, ω, η, β = p #= du\[1\]…

---

## [Select observations in a DataFrame from variable with some missing observations](https://discourse.julialang.org/t/select-observations-in-a-dataframe-from-variable-with-some-missing-observations/59427)

<div class="topic-metadata">

**Author:** [@Albert\_Zevelev](https://discourse.julialang.org/u/Albert_Zevelev)\
**Replies:** 15\
**Last updated:** [April 17, 2021, 2:02am UTC](https://discourse.julialang.org/t/select-observations-in-a-dataframe-from-variable-with-some-missing-observations/59427 "2021-04-17T02:02:44Z")

</div>

using CSV, HTTP, DataFrames link = "https://raw.githubusercontent.com/azev77/azev77/main/HP\_m.csv"; r = HTTP.get(link) d = CSV.read(r.body, DataFrame) d = d\[(d.sizerank .\<= 50), :\] ERROR: ArgumentError: unable to check …

---

## [Understanding Stheno example](https://discourse.julialang.org/t/understanding-stheno-example/59450)

<div class="topic-metadata">

**Author:** [@jzr](https://discourse.julialang.org/u/jzr)\
**Replies:** 1\
**Last updated:** [April 16, 2021, 11:40pm UTC](https://discourse.julialang.org/t/understanding-stheno-example/59450 "2021-04-16T23:40:35Z")

</div>

This example fits a GP and plots something. I am trying to understand all the objects here. using Stheno using Stheno.AbstractGPs using CairoMakie # Short length-scale and small variance. const l1 = 0.4 const s1 = 0.2…

---

## [Second Order DE producing incorrect results](https://discourse.julialang.org/t/second-order-de-producing-incorrect-results/59380)

<div class="topic-metadata">

**Author:** [@daviiinsky](https://discourse.julialang.org/u/daviiinsky)\
**Replies:** 3\
**Last updated:** [April 16, 2021, 10:38pm UTC](https://discourse.julialang.org/t/second-order-de-producing-incorrect-results/59380 "2021-04-16T22:38:10Z")

</div>

Hello! I was working on the following problem where I’m integrating a second order differential equation. Initially I tried putting it into the 2nd Order Solver in DifferentialEquations.jl, where it did produce a plot s…

---

## [Notes on \`CUDA.sync\_threads\` and dispatch on \`Union\`](https://discourse.julialang.org/t/notes-on-cuda-sync-threads-and-dispatch-on-union/59375)

<div class="topic-metadata">

**Author:** [@tkf](https://discourse.julialang.org/u/tkf)\
**Replies:** 3\
**Last updated:** [April 16, 2021, 9:11pm UTC](https://discourse.julialang.org/t/notes-on-cuda-sync-threads-and-dispatch-on-union/59375 "2021-04-16T21:11:56Z")

</div>

I’ve been playing with Union-typed objects on CUDA GPU and I found an interesting quirk due to how sync\_threads and Union-splitting interacts. I thought to share this here since it’s not really a CUDA.jl issue. MWE If C…

---

## [CUDA not working after today's update](https://discourse.julialang.org/t/cuda-not-working-after-todays-update/59329)

<div class="topic-metadata">

**Author:** [@Ferran\_Mazzanti](https://discourse.julialang.org/u/Ferran_Mazzanti)\
**Replies:** 2\
**Last updated:** [April 16, 2021, 8:35pm UTC](https://discourse.julialang.org/t/cuda-not-working-after-todays-update/59329 "2021-04-16T20:35:45Z")

</div>

Hi, yesterday I read the message about the new CUDA package. Today I just did an update (julia 1.6.0 on ubuntu mate 20.04) and the CUDA package did upgrade. After that julia\> using CUDA julia\> CUDA.zeros(10) ┌ Error:…

---

## [CAS Best Practices](https://discourse.julialang.org/t/cas-best-practices/58092)

<div class="topic-metadata">

**Author:** [@JeffreySarnoff](https://discourse.julialang.org/u/JeffreySarnoff)\
**Replies:** 87\
**Last updated:** [April 16, 2021, 6:41pm UTC](https://discourse.julialang.org/t/cas-best-practices/58092 "2021-04-16T18:41:59Z")

</div>

{@admin, if it makes good sense, please create a domain for all things Symbolically Maths+Logics (Symbolic Solutions? \[your choice\] ) and move this topic there - - thank you} @rfateman @certik @carette What is your pers…

---

## [Gadfly: How to change width and opacity of lines in Geom.density?](https://discourse.julialang.org/t/gadfly-how-to-change-width-and-opacity-of-lines-in-geom-density/37823)

<div class="topic-metadata">

**Author:** [@NightMachinary](https://discourse.julialang.org/u/NightMachinary)\
**Replies:** 5\
**Last updated:** [April 16, 2021, 5:17pm UTC](https://discourse.julialang.org/t/gadfly-how-to-change-width-and-opacity-of-lines-in-geom-density/37823 "2021-04-16T17:17:08Z")

</div>

I tried Theme(alphas = \[0.3\], line\_width=10cm), but it didn’t work.

---

## [The difficult task of comparing supervised models](https://discourse.julialang.org/t/the-difficult-task-of-comparing-supervised-models/59148)

<div class="topic-metadata">

**Author:** [@sylvaticus](https://discourse.julialang.org/u/sylvaticus)\
**Replies:** 3\
**Last updated:** [April 16, 2021, 4:27pm UTC](https://discourse.julialang.org/t/the-difficult-task-of-comparing-supervised-models/59148 "2021-04-16T16:27:29Z")

</div>

I read often blogs or even academic articles that compare different machine learning for a specific tasks, ending up of a ranking based on lower MSE or maximum accuracy for example. These comparisons are done by just ap…

---

## [ArchGDAL.jl (or GDAL.jl not sure) - Undesired behaviour when reprojecting coordinates to EPSG 4326](https://discourse.julialang.org/t/archgdal-jl-or-gdal-jl-not-sure-undesired-behaviour-when-reprojecting-coordinates-to-epsg-4326/59415)

<div class="topic-metadata">

**Author:** [@carlosmolinero](https://discourse.julialang.org/u/carlosmolinero)\
**Replies:** 3\
**Last updated:** [April 16, 2021, 3:24pm UTC](https://discourse.julialang.org/t/archgdal-jl-or-gdal-jl-not-sure-undesired-behaviour-when-reprojecting-coordinates-to-epsg-4326/59415 "2021-04-16T15:24:07Z")

</div>

Hello, I am fairly new to Julia and absolutely new to ArchGDAL, so please excuse me if what I am reporting is actually a misconception on my part. I would like to first thank the developers of both the language and the p…

---

## [A partition and a crossValidation function over arbitrary number of n-dimensional arrays](https://discourse.julialang.org/t/a-partition-and-a-crossvalidation-function-over-arbitrary-number-of-n-dimensional-arrays/59343)

<div class="topic-metadata">

**Author:** [@sylvaticus](https://discourse.julialang.org/u/sylvaticus)\
**Replies:** 0\
**Last updated:** [April 15, 2021, 1:50pm UTC](https://discourse.julialang.org/t/a-partition-and-a-crossvalidation-function-over-arbitrary-number-of-n-dimensional-arrays/59343 "2021-04-15T13:50:15Z")

</div>

Hello, for my own machine learning library, I implemented the following functions to partition and run cross-validation over a m-set of n-dimensional arrays, where one can specify the dimension to partition or run the cr…

---

## [Interactive audio spectrograms - new user](https://discourse.julialang.org/t/interactive-audio-spectrograms-new-user/59280)

<div class="topic-metadata">

**Author:** [@CosmicSpittle](https://discourse.julialang.org/u/CosmicSpittle)\
**Replies:** 5\
**Last updated:** [April 15, 2021, 1:55pm UTC](https://discourse.julialang.org/t/interactive-audio-spectrograms-new-user/59280 "2021-04-15T13:55:45Z")

</div>

I am new to Julia and would like to visualize, annotate, and listen to audio clips, eventually in a Pluto notebook. Ideally, I would like to import a sound file and create a spectrogram with a play button to hear the cl…

---

## [Visual workflow tool for Julia - let's build one!](https://discourse.julialang.org/t/visual-workflow-tool-for-julia-lets-build-one/9384)

<div class="topic-metadata">

**Author:** [@xiaodai](https://discourse.julialang.org/u/xiaodai)\
**Replies:** 24\
**Last updated:** [April 15, 2021, 11:48am UTC](https://discourse.julialang.org/t/visual-workflow-tool-for-julia-lets-build-one/9384 "2021-04-15T11:48:47Z")

</div>

I have always liked visual data science and machine learning tools that let you use a mixture of flowcharts and code to write data manipulation and machine learning models. There are some popular ones out there including…

---

## [Julia contour lines issue](https://discourse.julialang.org/t/julia-contour-lines-issue/59333)

<div class="topic-metadata">

**Author:** [@safhjkas](https://discourse.julialang.org/u/safhjkas)\
**Replies:** 1\
**Last updated:** [April 15, 2021, 11:33am UTC](https://discourse.julialang.org/t/julia-contour-lines-issue/59333 "2021-04-15T11:33:51Z")

</div>

i am trying to sketch a contour lines plot by the code, but it shows “ERROR: UndefVarError: K not defined” can anyone help on how to define the K? xvec = GradientDescent(\[1;1\]) plot!(xvec\[1,1:1:K\], xvec\[2,1:1:K\], lw = …

---

## [Transparent group / layers for graphical union](https://discourse.julialang.org/t/transparent-group-layers-for-graphical-union/59321)

<div class="topic-metadata">

**Author:** [@goretkin](https://discourse.julialang.org/u/goretkin)\
**Replies:** 0\
**Last updated:** [April 15, 2021, 9:06am UTC](https://discourse.julialang.org/t/transparent-group-layers-for-graphical-union/59321 "2021-04-15T09:06:09Z")

</div>

SVG has a feature that allows grouping plot elements. This g tag can have its opacity adjusted, which is different than adjusting the opacity of the individual elements as demonstrated in this image from this answer wher…

---

## [Frequency Response Functions (FRF) in Julia](https://discourse.julialang.org/t/frequency-response-functions-frf-in-julia/57900)

<div class="topic-metadata">

**Author:** [@Eggy](https://discourse.julialang.org/u/Eggy)\
**Replies:** 49\
**Last updated:** [April 15, 2021, 3:36am UTC](https://discourse.julialang.org/t/frequency-response-functions-frf-in-julia/57900 "2021-04-15T03:36:24Z")

</div>

I have followed Julia for a while, but I am now just getting into using it more. I have collected data from performing what’s known as an roving hammer test with my accelerometer and an non-instrumented hammer to derive …

---

## [Updating expressions for indicator constraints in JuMP](https://discourse.julialang.org/t/updating-expressions-for-indicator-constraints-in-jump/59059)

<div class="topic-metadata">

**Author:** [@Maria95](https://discourse.julialang.org/u/Maria95)\
**Replies:** 7\
**Last updated:** [April 14, 2021, 9:28pm UTC](https://discourse.julialang.org/t/updating-expressions-for-indicator-constraints-in-jump/59059 "2021-04-14T21:28:20Z")

</div>

Hello, I am trying to implement a constraint with a conditional statement that I am making piecewise affine by introducing binary variables and using the big M method. I know that JuMP supports indicator constraints but …

---

## [Packages for game theory](https://discourse.julialang.org/t/packages-for-game-theory/59255)

<div class="topic-metadata">

**Author:** [@brett\_knoss](https://discourse.julialang.org/u/brett_knoss)\
**Replies:** 2\
**Last updated:** [April 14, 2021, 9:22pm UTC](https://discourse.julialang.org/t/packages-for-game-theory/59255 "2021-04-14T21:22:16Z")

</div>

What packages are there for game theory?

---

## [Gurobi with StochasticPrograms.jl](https://discourse.julialang.org/t/gurobi-with-stochasticprograms-jl/59139)

<div class="topic-metadata">

**Author:** [@arfuentes97](https://discourse.julialang.org/u/arfuentes97)\
**Replies:** 8\
**Last updated:** [April 14, 2021, 4:31pm UTC](https://discourse.julialang.org/t/gurobi-with-stochasticprograms-jl/59139 "2021-04-14T16:31:35Z")

</div>

Hi there, I’m trying to use Gurobi solver to optimize the farmer problem proposed in StochasticPrograms.jl and I get the following error message: ERROR: MethodError: no method matching all\_decisions(::DeterministicEqui…

---

## [Adding noise in frequency domain while solving an SPDE](https://discourse.julialang.org/t/adding-noise-in-frequency-domain-while-solving-an-spde/59240)

<div class="topic-metadata">

**Author:** [@tiago](https://discourse.julialang.org/u/tiago)\
**Replies:** 3\
**Last updated:** [April 14, 2021, 2:35pm UTC](https://discourse.julialang.org/t/adding-noise-in-frequency-domain-while-solving-an-spde/59240 "2021-04-14T14:35:45Z")

</div>

Hello, I’m implementing a numerical solver to a certain kind of a 2D stochastic PDE using Fourier Transforms. So, this solver is a Galerkin type method, which means that choosing the right basis functions I can apply F…

---

## [Parallel computing for eigs() function](https://discourse.julialang.org/t/parallel-computing-for-eigs-function/22926)

<div class="topic-metadata">

**Author:** [@saeed](https://discourse.julialang.org/u/saeed)\
**Replies:** 10\
**Last updated:** [April 14, 2021, 12:45pm UTC](https://discourse.julialang.org/t/parallel-computing-for-eigs-function/22926 "2021-04-14T12:45:46Z")

</div>

Hello, I am new to julia and parallel computing. I want to use parallel computing capability in julia in doing shift-invert calculations. My problem is that I have a couple of sparse matrices, and want to find specific e…

---

## [Adding related work to a multilevel Turing model](https://discourse.julialang.org/t/adding-related-work-to-a-multilevel-turing-model/59182)

<div class="topic-metadata">

**Author:** [@rikh](https://discourse.julialang.org/u/rikh)\
**Replies:** 4\
**Last updated:** [April 14, 2021, 12:43pm UTC](https://discourse.julialang.org/t/adding-related-work-to-a-multilevel-turing-model/59182 "2021-04-14T12:43:50Z")

</div>

Suppose that we have fitted a multilevel model over data from multiple groups called A, B, C and D and that we’re trying to estimate the population means for these 4 groups. For example, this could look something like th…

---

## [GPU and Thread-Parallel Support for Turing.jl](https://discourse.julialang.org/t/gpu-and-thread-parallel-support-for-turing-jl/58958)

<div class="topic-metadata">

**Author:** [@Koshroy](https://discourse.julialang.org/u/Koshroy)\
**Replies:** 1\
**Last updated:** [April 13, 2021, 10:03pm UTC](https://discourse.julialang.org/t/gpu-and-thread-parallel-support-for-turing-jl/58958 "2021-04-13T22:03:20Z")

</div>

Hey all, I’m a bit new to the Julia ecosystem and had a couple questions that some searching around didn’t answer: Is there a way to use the GPU to sample for Turing.jl models? And if there isn’t, is there a way to tr…

---

## [How to export data in arrays form?](https://discourse.julialang.org/t/how-to-export-data-in-arrays-form/57564)

<div class="topic-metadata">

**Author:** [@RaquelSantos](https://discourse.julialang.org/u/RaquelSantos)\
**Replies:** 11\
**Last updated:** [April 13, 2021, 4:00pm UTC](https://discourse.julialang.org/t/how-to-export-data-in-arrays-form/57564 "2021-04-13T16:00:03Z")

</div>

Hello in the database I have this data: 16×3 Array{Any,2}: "P1\_BloEco\_m" 1 0.01 "P1\_BloEco\_s" 2 0.06 "P1\_R" 3 0.22 "P1\_R" 4 0.242 "P2\_R" 5 0.015 "P2\_R" 6 0.06 "P3\_A"…

---

## [Markers with ribbon](https://discourse.julialang.org/t/markers-with-ribbon/59207)

<div class="topic-metadata">

**Author:** [@eschoute](https://discourse.julialang.org/u/eschoute)\
**Replies:** 0\
**Last updated:** [April 13, 2021, 3:15pm UTC](https://discourse.julialang.org/t/markers-with-ribbon/59207 "2021-04-13T15:15:03Z")

</div>

I want to have a plot with only markers on the mean and not on the ribbon. Example using Plots pgfplotsx() plot( 1:10, rand(10), ribbon = 0.1 \* rand(1:10), markers = :auto ) savefig("pgfplot.png") gr()…

---

## [Use Dictionary value in objective function](https://discourse.julialang.org/t/use-dictionary-value-in-objective-function/59119)

<div class="topic-metadata">

**Author:** [@rox](https://discourse.julialang.org/u/rox)\
**Replies:** 8\
**Last updated:** [April 13, 2021, 2:46pm UTC](https://discourse.julialang.org/t/use-dictionary-value-in-objective-function/59119 "2021-04-13T14:46:29Z")

</div>

Hello, I’m trying to be able to use values put in a Dictionary to weight the variables that are going to be minimized in a JuMP objective function. The dictionnary is implemented as follow : Dicopond = Dict(0=\> 1, 1 …

---

## [Difference between sum over indexed array or equivalent view on the array](https://discourse.julialang.org/t/difference-between-sum-over-indexed-array-or-equivalent-view-on-the-array/59197)

<div class="topic-metadata">

**Author:** [@oheil](https://discourse.julialang.org/u/oheil)\
**Replies:** 0\
**Last updated:** [April 13, 2021, 1:43pm UTC](https://discourse.julialang.org/t/difference-between-sum-over-indexed-array-or-equivalent-view-on-the-array/59197 "2021-04-13T13:43:25Z")

</div>

The difference is small, but I can’t figure out, why there is any difference and where this uncertainty comes from. The following code creates a Vector of random Float64 and puts randomly NaN into it. It calculates the …

---

## [How to filter columns of a matrix by columns of another matrix](https://discourse.julialang.org/t/how-to-filter-columns-of-a-matrix-by-columns-of-another-matrix/54061)

<div class="topic-metadata">

**Author:** [@Shazman](https://discourse.julialang.org/u/Shazman)\
**Replies:** 28\
**Last updated:** [April 12, 2021, 10:36pm UTC](https://discourse.julialang.org/t/how-to-filter-columns-of-a-matrix-by-columns-of-another-matrix/54061 "2021-04-12T22:36:58Z")

</div>

Hi I have two matrics in Julia, both matrics are coded by 0,1,2. and I want to exclude the columns of matrix B from columns of matrix A. at the end, I will have new matrix with ( 28960x 41227). how can I do it ? tha…

---

## [JuMP 0.21.7 released](https://discourse.julialang.org/t/jump-0-21-7-released/59131)

<div class="topic-metadata">

**Author:** [@odow](https://discourse.julialang.org/u/odow)\
**Replies:** 0\
**Last updated:** [April 12, 2021, 8:42pm UTC](https://discourse.julialang.org/t/jump-0-21-7-released/59131 "2021-04-12T20:42:18Z")

</div>

Dear all, We are happy to announce the release of JuMP 0.21.7. This should be a non-breaking release, please let us know if this isn’t the case by opening a Github issue or joining the developer chatroom. A key feature…

---

## [CUDA atomics on complex-valued arrays](https://discourse.julialang.org/t/cuda-atomics-on-complex-valued-arrays/59054)

<div class="topic-metadata">

**Author:** [@weylspinor](https://discourse.julialang.org/u/weylspinor)\
**Replies:** 3\
**Last updated:** [April 12, 2021, 2:52pm UTC](https://discourse.julialang.org/t/cuda-atomics-on-complex-valued-arrays/59054 "2021-04-12T14:52:57Z")

</div>

Hi, I am curious if there is an way to do atomic operations on complex-valued arrays in CUDA kernel, e.g. using CUDA function kernel!(x::CuDeviceArray{T}, y::CuDeviceArray{T}) where T i = (blockIdx().x-1)\*blockDim…

[Previous page](https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=373)

[Next page](https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=375)