# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=91

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

**Page:** 92

---

## [ERROR: The objective function (erf) is not supported by JuMP](https://discourse.julialang.org/t/error-the-objective-function-erf-is-not-supported-by-jump/48302)

<div class="topic-metadata">

**Author:** [@BuRanran](https://discourse.julialang.org/u/BuRanran)\
**Replies:** 6\
**Last updated:** [August 13, 2024, 10:17pm UTC](https://discourse.julialang.org/t/error-the-objective-function-erf-is-not-supported-by-jump/48302 "2024-08-13T22:17:46Z")

</div>

I have a non-linear optimization problem to be solved with JuMP and IPOPT solver. The objective function is a probability distribution function of a normal distribution. It can be optimized by IPOPT directly, but not sup…

---

## [In Turing.jl get probability of the answer of the datapoint from validation set](https://discourse.julialang.org/t/in-turing-jl-get-probability-of-the-answer-of-the-datapoint-from-validation-set/118103)

<div class="topic-metadata">

**Author:** [@Jakub\_Mitura](https://discourse.julialang.org/u/Jakub_Mitura)\
**Replies:** 4\
**Last updated:** [August 13, 2024, 2:12pm UTC](https://discourse.julialang.org/t/in-turing-jl-get-probability-of-the-answer-of-the-datapoint-from-validation-set/118103 "2024-08-13T14:12:36Z")

</div>

Hello I am new to probabilistic programming and some (I suppose basic things) Firs my goal is to design model that given set of features will predict binary outcome variable. Hovewer additionally I would like to know a…

---

## [Using DGMulti FDSBP with parabolic terms in Trixi?](https://discourse.julialang.org/t/using-dgmulti-fdsbp-with-parabolic-terms-in-trixi/118088)

<div class="topic-metadata">

**Author:** [@Kelian\_Renoux](https://discourse.julialang.org/u/Kelian_Renoux)\
**Replies:** 4\
**Last updated:** [August 13, 2024, 2:10pm UTC](https://discourse.julialang.org/t/using-dgmulti-fdsbp-with-parabolic-terms-in-trixi/118088 "2024-08-13T14:10:37Z")

</div>

Hi, I am comparing the methods in the DGMulti Solver from Trixi with a visquous example but when I try to use the Finite difference methods periodic\_derivative\_operator(derivative\_order=1, accuracy\_order=4, xmin=0.0, xma…

---

## [Simulating quantum Hamiltonian evolution with Yao](https://discourse.julialang.org/t/simulating-quantum-hamiltonian-evolution-with-yao/117287)

<div class="topic-metadata">

**Author:** [@jzzhuang](https://discourse.julialang.org/u/jzzhuang)\
**Replies:** 8\
**Last updated:** [August 13, 2024, 12:37pm UTC](https://discourse.julialang.org/t/simulating-quantum-hamiltonian-evolution-with-yao/117287 "2024-08-13T12:37:58Z")

</div>

Hi everyone, I’ve been using Yao.jl to simulate quantum evolution and encountered an issue with the time evolution function being unexpectedly slow. Notably, it performs much slower than in Mathematica. Here’s a snippet…

---

## [Type problems in ForwardDiff with preallocations](https://discourse.julialang.org/t/type-problems-in-forwarddiff-with-preallocations/118131)

<div class="topic-metadata">

**Author:** [@Chandrasekhar](https://discourse.julialang.org/u/Chandrasekhar)\
**Replies:** 2\
**Last updated:** [August 13, 2024, 12:32pm UTC](https://discourse.julialang.org/t/type-problems-in-forwarddiff-with-preallocations/118131 "2024-08-13T12:32:46Z")

</div>

Hi everyone! I am solving a system of non-linear equations by using nlsolve. I want to use ForwardDiff to calculate the Jacobian inside nlsolve. The code which is running without any errors is the following: function g…

---

## [Extending JuMP @variable](https://discourse.julialang.org/t/extending-jump-variable/118094)

<div class="topic-metadata">

**Author:** [@shawn\_T](https://discourse.julialang.org/u/shawn_T)\
**Replies:** 7\
**Last updated:** [August 13, 2024, 9:41am UTC](https://discourse.julialang.org/t/extending-jump-variable/118094 "2024-08-13T09:41:59Z")

</div>

Hi, I am planning to extend JuMP @variable macro by defining a new struct to replace the VariableInfo struct defined in JuMP, the code below is following the extension page: struct My\_var \<: JuMP.AbstractVariable …

---

## [Nested optimization - matrix multiplication and internal functions](https://discourse.julialang.org/t/nested-optimization-matrix-multiplication-and-internal-functions/118098)

<div class="topic-metadata">

**Author:** [@blob](https://discourse.julialang.org/u/blob)\
**Replies:** 9\
**Last updated:** [August 13, 2024, 9:25am UTC](https://discourse.julialang.org/t/nested-optimization-matrix-multiplication-and-internal-functions/118098 "2024-08-13T09:25:41Z")

</div>

I have a nested optimization problem in JuMP that fails to run because of Dual going through. In my original problem the lower level problem is a convex QP so it is possible to compute correct gradients but first the cod…

---

## [Custom xticks for dates in StatsPlots groupedbar](https://discourse.julialang.org/t/custom-xticks-for-dates-in-statsplots-groupedbar/118112)

<div class="topic-metadata">

**Author:** [@slwu89](https://discourse.julialang.org/u/slwu89)\
**Replies:** 1\
**Last updated:** [August 13, 2024, 8:33am UTC](https://discourse.julialang.org/t/custom-xticks-for-dates-in-statsplots-groupedbar/118112 "2024-08-13T08:33:47Z")

</div>

Hi all, can someone help me understand why my code is not able to produce a plot with custom xticks for a Date x-axis? I would like to plot the time axis using ticks that are spaced out more widely. using DataFrames, St…

---

## [\[Makie\] Get current theme](https://discourse.julialang.org/t/makie-get-current-theme/81564)

<div class="topic-metadata">

**Author:** [@TheLateKronos](https://discourse.julialang.org/u/TheLateKronos)\
**Replies:** 4\
**Last updated:** [August 13, 2024, 7:03am UTC](https://discourse.julialang.org/t/makie-get-current-theme/81564 "2024-08-13T07:03:35Z")

</div>

When using with\_theme, the first argument is a theme, and keyword arguments modify the given theme. This is great if I have a variable bound to the current theme, and I want to make a modification to it only for the foll…

---

## [Using PreallocationTools with LinearSolve](https://discourse.julialang.org/t/using-preallocationtools-with-linearsolve/98508)

<div class="topic-metadata">

**Author:** [@clm](https://discourse.julialang.org/u/clm)\
**Replies:** 3\
**Last updated:** [August 12, 2024, 8:54pm UTC](https://discourse.julialang.org/t/using-preallocationtools-with-linearsolve/98508 "2024-08-12T20:54:48Z")

</div>

I’m trying to solve a large 2D PDE using this example as a template. I’m effectively trying to solve some simplified (though still nonlinear) pseudo-Boussinesq Navier Stokes equations where I evolve u and temperature and…

---

## [ODE-BVP's with Unknown Parameter](https://discourse.julialang.org/t/ode-bvps-with-unknown-parameter/28873)

<div class="topic-metadata">

**Author:** [@anodos](https://discourse.julialang.org/u/anodos)\
**Replies:** 9\
**Last updated:** [August 12, 2024, 9:50am UTC](https://discourse.julialang.org/t/ode-bvps-with-unknown-parameter/28873 "2024-08-12T09:50:59Z")

</div>

Matlab’s bvp4c allows the user to specify ODE-BVP problems which contain an unknown parameter, and then to specify the problem by providing an extra boundary condition. E.g. for a second order ODE, we might have an extra…

---

## [Auto-gradient with Symbolics for JuMP constraints](https://discourse.julialang.org/t/auto-gradient-with-symbolics-for-jump-constraints/117953)

<div class="topic-metadata">

**Author:** [@vguy-deroubaix](https://discourse.julialang.org/u/vguy-deroubaix)\
**Replies:** 6\
**Last updated:** [August 11, 2024, 8:13pm UTC](https://discourse.julialang.org/t/auto-gradient-with-symbolics-for-jump-constraints/117953 "2024-08-11T20:13:23Z")

</div>

Hello, for a project of optimal approximation of functions, I need the expression of the gradient of the function I need to approximate, so I can put these expressions in constraints in a JuMP model (with Ipopt as the so…

---

## [Creating a custom container layer in Lux](https://discourse.julialang.org/t/creating-a-custom-container-layer-in-lux/117979)

<div class="topic-metadata">

**Author:** [@rkube](https://discourse.julialang.org/u/rkube)\
**Replies:** 2\
**Last updated:** [August 11, 2024, 7:31pm UTC](https://discourse.julialang.org/t/creating-a-custom-container-layer-in-lux/117979 "2024-08-11T19:31:18Z")

</div>

Hi, I’m trying to implement a custom container layer in Lux, following the manual to bind a custom masked linear layer together. The idea is that each masked layer has a user-defined mask, and all masks need to be set f…

---

## [Hamiltonian Monte Carlo on sphere](https://discourse.julialang.org/t/hamiltonian-monte-carlo-on-sphere/117571)

<div class="topic-metadata">

**Author:** [@Gattu\_Mytraya](https://discourse.julialang.org/u/Gattu_Mytraya)\
**Replies:** 21\
**Last updated:** [August 11, 2024, 1:48pm UTC](https://discourse.julialang.org/t/hamiltonian-monte-carlo-on-sphere/117571 "2024-08-11T13:48:42Z")

</div>

I have a PDF defined on (S^{2})^{D} that I want to sample from using Hamiltonian Monte Carlo (HMC). I need to calculate the expectation value of a function against this PDF, which is computationally expensive. Therefore,…

---

## [Replacing FFT from Numerical Recipes with FFTW](https://discourse.julialang.org/t/replacing-fft-from-numerical-recipes-with-fftw/55508)

<div class="topic-metadata">

**Author:** [@edwinb-ai](https://discourse.julialang.org/u/edwinb-ai)\
**Replies:** 8\
**Last updated:** [August 11, 2024, 12:03pm UTC](https://discourse.julialang.org/t/replacing-fft-from-numerical-recipes-with-fftw/55508 "2024-08-11T12:03:17Z")

</div>

Hello there. I’m tasked to port an old FORTRAN 77 legacy code to Julia. Unfortunately, I’m stuck with the computation of a Fast Fourier Transform (FFT). The original legacy code uses the sinft routine from the Numerica…

---

## [Modelling simple hydraulic using MTK Library](https://discourse.julialang.org/t/modelling-simple-hydraulic-using-mtk-library/118028)

<div class="topic-metadata">

**Author:** [@romantimo](https://discourse.julialang.org/u/romantimo)\
**Replies:** 0\
**Last updated:** [August 10, 2024, 1:34pm UTC](https://discourse.julialang.org/t/modelling-simple-hydraulic-using-mtk-library/118028 "2024-08-10T13:34:04Z")

</div>

Hi everyone, I’ll appreciate an advice on how to split fluid flow using MTK Standard Library. Volume1 (pressured) connected to tube1. Tube1 connected to tube2 and tube3. tube2 and tube3 connected to empty volumes 2 and…

---

## [Tell SciML about Jacobian/VJP of ODEFunction](https://discourse.julialang.org/t/tell-sciml-about-jacobian-vjp-of-odefunction/117986)

<div class="topic-metadata">

**Author:** [@hexaeder](https://discourse.julialang.org/u/hexaeder)\
**Replies:** 2\
**Last updated:** [August 10, 2024, 5:58am UTC](https://discourse.julialang.org/t/tell-sciml-about-jacobian-vjp-of-odefunction/117986 "2024-08-10T05:58:31Z")

</div>

Hello, I have a class of ODEFunctions for which I know how to exploit a lot of the internal structure for efficient calculations of Jacobians. I am a bit confused about how I may teach the SciML-universe about those. Ge…

---

## [Parallel adaptive time-stepping for ODE problems at different time-scales](https://discourse.julialang.org/t/parallel-adaptive-time-stepping-for-ode-problems-at-different-time-scales/117982)

<div class="topic-metadata">

**Author:** [@SteffenPL](https://discourse.julialang.org/u/SteffenPL)\
**Replies:** 1\
**Last updated:** [August 9, 2024, 10:55pm UTC](https://discourse.julialang.org/t/parallel-adaptive-time-stepping-for-ode-problems-at-different-time-scales/117982 "2024-08-09T22:55:28Z")

</div>

I’m wondering if there is already a mechanism for ugly coupling of differential equations. In my application, I have one large-dimensional SDE and a reaction-diffusion PDE, which are coupled and have different time scal…

---

## [MTK error messages, change of use?](https://discourse.julialang.org/t/mtk-error-messages-change-of-use/117931)

<div class="topic-metadata">

**Author:** [@LaraSchmalenstroer](https://discourse.julialang.org/u/LaraSchmalenstroer)\
**Replies:** 6\
**Last updated:** [August 9, 2024, 5:51pm UTC](https://discourse.julialang.org/t/mtk-error-messages-change-of-use/117931 "2024-08-09T17:51:51Z")

</div>

Hi, I’m relatively new to Julia, so maybe I don’t see the problem here. I’m currently working with ModelingToolkit. To get used to the functionalities, I created a small model last week (which worked perfectly). using …

---

## [How to return additional arguments when optimizing or finding a root](https://discourse.julialang.org/t/how-to-return-additional-arguments-when-optimizing-or-finding-a-root/117994)

<div class="topic-metadata">

**Author:** [@jovansam](https://discourse.julialang.org/u/jovansam)\
**Replies:** 6\
**Last updated:** [August 9, 2024, 4:12pm UTC](https://discourse.julialang.org/t/how-to-return-additional-arguments-when-optimizing-or-finding-a-root/117994 "2024-08-09T16:12:02Z")

</div>

Hi All, I am looking for some ideas about how others have often handled this issue. Often, I have to solve an optimization problem and then pass out return some additional arguments. In the MWE example below, y is the c…

---

## [Solving Diophantine equations using Julia](https://discourse.julialang.org/t/solving-diophantine-equations-using-julia/41829)

<div class="topic-metadata">

**Author:** [@Angel\_Barria\_Comiche](https://discourse.julialang.org/u/Angel_Barria_Comiche)\
**Replies:** 3\
**Last updated:** [August 9, 2024, 5:12am UTC](https://discourse.julialang.org/t/solving-diophantine-equations-using-julia/41829 "2024-08-09T05:12:42Z")

</div>

Hi, I am new with Julia and I was wondering how can I solve a system of diophantine equations adding conditions to some of the variables. For example, I would like to find integers x, y, p, h, r, t that solve the equatio…

---

## [ModellingToolkit and arrays](https://discourse.julialang.org/t/modellingtoolkit-and-arrays/117722)

<div class="topic-metadata">

**Author:** [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Replies:** 6\
**Last updated:** [August 8, 2024, 5:47pm UTC](https://discourse.julialang.org/t/modellingtoolkit-and-arrays/117722 "2024-08-08T17:47:06Z")

</div>

I have the following code: # Example one: Falling mass. using ModelingToolkit, OrdinaryDiffEq G\_EARTH::Vector{Float64} = \[0.0, 0.0, -9.81\] # gravitational acceleration \[m/s²\] # definiting the model @independent…

---

## [How to get a Semi transparent sphere in Makie?](https://discourse.julialang.org/t/how-to-get-a-semi-transparent-sphere-in-makie/117944)

<div class="topic-metadata">

**Author:** [@kellertuer](https://discourse.julialang.org/u/kellertuer)\
**Replies:** 2\
**Last updated:** [August 8, 2024, 5:37pm UTC](https://discourse.julialang.org/t/how-to-get-a-semi-transparent-sphere-in-makie/117944 "2024-08-08T17:37:47Z")

</div>

A few years back I asked a question, that I could not fully resolve. At JuliaCon I think I heard it is now possible, so I’ll give it a new try. If I do something like (e.g. in a Pluto cell) begin using WGLMakie, Colors,…

---

## [DataFrames range binning](https://discourse.julialang.org/t/dataframes-range-binning/93190)

<div class="topic-metadata">

**Author:** [@alex-s-gardner](https://discourse.julialang.org/u/alex-s-gardner)\
**Replies:** 4\
**Last updated:** [August 8, 2024, 4:07pm UTC](https://discourse.julialang.org/t/dataframes-range-binning/93190 "2024-08-08T16:07:03Z")

</div>

I would like to perform efficient block-wise statistics on binned variables… and I can’t find an elegant solution. given: using DataFrames df = DataFrame(x = rand(100000), y = rand(100000), v = rand(100000)) I would l…

---

## [JSON3 read \`Dict{Tuple{Int,Int}, T}\` unexpected behavior](https://discourse.julialang.org/t/json3-read-dict-tuple-int-int-t-unexpected-behavior/117759)

<div class="topic-metadata">

**Author:** [@guimarqu](https://discourse.julialang.org/u/guimarqu)\
**Replies:** 4\
**Last updated:** [August 8, 2024, 3:24pm UTC](https://discourse.julialang.org/t/json3-read-dict-tuple-int-int-t-unexpected-behavior/117759 "2024-08-08T15:24:33Z")

</div>

Hey, I’m using JSON3.jl in a project and I found this unexpected behavior when reading Dict{Tuple{Int,Int}, T}. I don’t know if I’m doing something wrong or if there is just a bug in the package but this is a quite cla…

---

## [MTK linearization: Change of use, or bug?](https://discourse.julialang.org/t/mtk-linearization-change-of-use-or-bug/117921)

<div class="topic-metadata">

**Author:** [@BLI](https://discourse.julialang.org/u/BLI)\
**Replies:** 8\
**Last updated:** [August 8, 2024, 10:07am UTC](https://discourse.julialang.org/t/mtk-linearization-change-of-use-or-bug/117921 "2024-08-08T10:07:04Z")

</div>

I recently asked about a linearization problem I had – the problem persists. However, here I raise another question: ModelingToolkit linearization fails for a simple problem that used to work. Question: What is it I do …

---

## [Plots.jl custom linestyle: longer dashes](https://discourse.julialang.org/t/plots-jl-custom-linestyle-longer-dashes/117772)

<div class="topic-metadata">

**Author:** [@mocalvao](https://discourse.julialang.org/u/mocalvao)\
**Replies:** 9\
**Last updated:** [August 8, 2024, 6:47am UTC](https://discourse.julialang.org/t/plots-jl-custom-linestyle-longer-dashes/117772 "2024-08-08T06:47:16Z")

</div>

I would like to insist whether there is a way to make a customized dash for the linestyle of Plots.jl, by choosing its length and the gap length as well among the dashes. There is a similar topic under Longer dashes in d…

---

## [Set a minimum level in contour plots](https://discourse.julialang.org/t/set-a-minimum-level-in-contour-plots/117907)

<div class="topic-metadata">

**Author:** [@Sh\_166](https://discourse.julialang.org/u/Sh_166)\
**Replies:** 9\
**Last updated:** [August 7, 2024, 11:42am UTC](https://discourse.julialang.org/t/set-a-minimum-level-in-contour-plots/117907 "2024-08-07T11:42:15Z")

</div>

I want to make a contour plot but I only want specific contours - or levels above a certain range. MWE: Pkg.add("Symbolics") Pkg.add("Plots") Pkg.add("LaTeXStrings") Pkg.add("Measures") Pkg.add("PlotThemes") using Sym…

---

## [Which attribute to use to adjust margin between subplot title and subplot placed above?](https://discourse.julialang.org/t/which-attribute-to-use-to-adjust-margin-between-subplot-title-and-subplot-placed-above/117902)

<div class="topic-metadata">

**Author:** [@lisapisa](https://discourse.julialang.org/u/lisapisa)\
**Replies:** 1\
**Last updated:** [August 7, 2024, 7:21am UTC](https://discourse.julialang.org/t/which-attribute-to-use-to-adjust-margin-between-subplot-title-and-subplot-placed-above/117902 "2024-08-07T07:21:37Z")

</div>

Heyy Julia community!! As always, thanks in advance for answering my noob questions. Love this community a lot and appreciate all of you helping out :slight\_smile: I am trying to plot two subplots in one plot, see exam…

---

## [\[crosspost\] JuliaDynamics meetings (poll closing soon!)](https://discourse.julialang.org/t/crosspost-juliadynamics-meetings-poll-closing-soon/117909)

<div class="topic-metadata">

**Author:** [@Datseris](https://discourse.julialang.org/u/Datseris)\
**Replies:** 0\
**Last updated:** [August 7, 2024, 7:09am UTC](https://discourse.julialang.org/t/crosspost-juliadynamics-meetings-poll-closing-soon/117909 "2024-08-07T07:09:34Z")

</div>

Hi all, cross-posting here Monthly meetups kickstart: JuliaDynamics (and beyond!) in case someone is subscribed to this particular category, which where all related discussion actually happens. I’ll close the poll at t…

[Previous page](https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=90)

[Next page](https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=92)