# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=83

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

**Page:** 84

---

## [ModelingToolkit -- possible to do "numeric" linearization?](https://discourse.julialang.org/t/modelingtoolkit-possible-to-do-numeric-linearization/118933)

<div class="topic-metadata">

**Author:** [@BLI](https://discourse.julialang.org/u/BLI)\
**Replies:** 6\
**Last updated:** [September 2, 2024, 12:00pm UTC](https://discourse.julialang.org/t/modelingtoolkit-possible-to-do-numeric-linearization/118933 "2024-09-02T12:00:22Z")

</div>

I’ve had problems doing linearization with ModelingToolkit \[MTK\] for “complicated” models since May (due to bugs?). I’m wondering whether it is possible to “massage” the MTK model into a form that allows for “old-fashion…

---

## [Matrix equation solution via GenericLinearAlgebra with BigFloat not working](https://discourse.julialang.org/t/matrix-equation-solution-via-genericlinearalgebra-with-bigfloat-not-working/119662)

<div class="topic-metadata">

**Author:** [@thedeyan](https://discourse.julialang.org/u/thedeyan)\
**Replies:** 1\
**Last updated:** [September 21, 2024, 3:45am UTC](https://discourse.julialang.org/t/matrix-equation-solution-via-genericlinearalgebra-with-bigfloat-not-working/119662 "2024-09-21T03:45:03Z")

</div>

I am trying to solve a system of linear equations: A \* x = B where A and B are real symmetric positive definite matrices with type BigFloat. I am trying to do the following: using GenericLinearAlgebra using LinearSol…

---

## [Training Bijectors.jl on samples](https://discourse.julialang.org/t/training-bijectors-jl-on-samples/119661)

<div class="topic-metadata">

**Author:** [@marcobonici](https://discourse.julialang.org/u/marcobonici)\
**Replies:** 3\
**Last updated:** [September 21, 2024, 2:45am UTC](https://discourse.julialang.org/t/training-bijectors-jl-on-samples/119661 "2024-09-21T02:45:40Z")

</div>

I need to train a Normalizing flow on some samples and then use it as a distribution. @Red-Portal suggested me to use Bijectors.jl. However, when trying to follow the example in the documentation, I noticed there is an …

---

## [Measure a certain computational base like |0\> or |1\>?](https://discourse.julialang.org/t/measure-a-certain-computational-base-like-0-or-1/119650)

<div class="topic-metadata">

**Author:** [@yao\_novice](https://discourse.julialang.org/u/yao_novice)\
**Replies:** 2\
**Last updated:** [September 20, 2024, 7:31pm UTC](https://discourse.julialang.org/t/measure-a-certain-computational-base-like-0-or-1/119650 "2024-09-20T19:31:56Z")

</div>

Simple qubit state: 1/5\*\[3, 4i\] measurement against |0\> should result in 0.36 against |1\> → 0.64 import Yao reg = Yao.ArrayReg(\[3.0, 4.0im\]) # a unnormalized state Yao.normalize!(reg) shots = 10000 m=Yao.measure(Ya…

---

## [Persistent vertex identities for Steiner tree, vertex removal](https://discourse.julialang.org/t/persistent-vertex-identities-for-steiner-tree-vertex-removal/119568)

<div class="topic-metadata">

**Author:** [@bremez](https://discourse.julialang.org/u/bremez)\
**Replies:** 7\
**Last updated:** [September 20, 2024, 2:32pm UTC](https://discourse.julialang.org/t/persistent-vertex-identities-for-steiner-tree-vertex-removal/119568 "2024-09-20T14:32:39Z")

</div>

I have a use case for a large graph, from which I iteratively remove vertices, and at each step compute some Steiner trees from its current state. Specifically, my use case requires to know to which vertices in the origi…

---

## [How to determine distribution of real-world data and then apply same distribution to model with Agents.jl](https://discourse.julialang.org/t/how-to-determine-distribution-of-real-world-data-and-then-apply-same-distribution-to-model-with-agents-jl/119617)

<div class="topic-metadata">

**Author:** [@tfranks](https://discourse.julialang.org/u/tfranks)\
**Replies:** 6\
**Last updated:** [September 20, 2024, 12:28pm UTC](https://discourse.julialang.org/t/how-to-determine-distribution-of-real-world-data-and-then-apply-same-distribution-to-model-with-agents-jl/119617 "2024-09-20T12:28:20Z")

</div>

Hello, Goal: trying to determine distribution from 4Q22 data set and apply the same distribution to a network model using Agents.jl. See 4Q22 data on xy-grid. Background: I had an earlier post on Discourse where …

---

## [Help needed for a simple static sum](https://discourse.julialang.org/t/help-needed-for-a-simple-static-sum/99744)

<div class="topic-metadata">

**Author:** [@francis-gagnon](https://discourse.julialang.org/u/francis-gagnon)\
**Replies:** 6\
**Last updated:** [September 20, 2024, 7:52am UTC](https://discourse.julialang.org/t/help-needed-for-a-simple-static-sum/99744 "2024-09-20T07:52:02Z")

</div>

Hi, I’m learning ModelingToolkit.jl and it’s my first experience with acausal modeling. I’m working on modeling a mining circuit. My flow variable is a mass flowrate in t/h (tonnage). I’m starting with a simple example,…

---

## [Parameter estimation in biological network](https://discourse.julialang.org/t/parameter-estimation-in-biological-network/119630)

<div class="topic-metadata">

**Author:** [@Nick1](https://discourse.julialang.org/u/Nick1)\
**Replies:** 7\
**Last updated:** [September 20, 2024, 6:55am UTC](https://discourse.julialang.org/t/parameter-estimation-in-biological-network/119630 "2024-09-20T06:55:37Z")

</div>

I am working on a large signaling pathway and trying to get a rough estimation of the baseline parameters. I have been trying to do the fitting with the Particle Swarm Optimization from Metaheuristics.jl but it does not …

---

## [Where to run CI on GPUs?](https://discourse.julialang.org/t/where-to-run-ci-on-gpus/119619)

<div class="topic-metadata">

**Author:** [@gdalle](https://discourse.julialang.org/u/gdalle)\
**Replies:** 3\
**Last updated:** [September 20, 2024, 6:16am UTC](https://discourse.julialang.org/t/where-to-run-ci-on-gpus/119619 "2024-09-20T06:16:43Z")

</div>

I have several packages whose tests would benefit from GPUs, but I don’t have funding to pay for dedicated servers. What are the best ways to run CI on GPUs with zero to low costs? My needs in terms of minutes are rather…

---

## [Differentiating through a QP - order of constraints](https://discourse.julialang.org/t/differentiating-through-a-qp-order-of-constraints/119275)

<div class="topic-metadata">

**Author:** [@blob](https://discourse.julialang.org/u/blob)\
**Replies:** 3\
**Last updated:** [September 20, 2024, 6:04am UTC](https://discourse.julialang.org/t/differentiating-through-a-qp-order-of-constraints/119275 "2024-09-20T06:04:17Z")

</div>

This is a follow-up to this topic. I have a QP that I want to differentiate through using DiffOpt. In contrast to the example from the tutorial, I have two constraints: n = 2 # variable dimension m = 2; # no of inequal…

---

## [History of \`isapprox\` in languages](https://discourse.julialang.org/t/history-of-isapprox-in-languages/119347)

<div class="topic-metadata">

**Author:** [@juliohm](https://discourse.julialang.org/u/juliohm)\
**Replies:** 56\
**Last updated:** [September 19, 2024, 8:58pm UTC](https://discourse.julialang.org/t/history-of-isapprox-in-languages/119347 "2024-09-19T20:58:20Z")

</div>

Does anyone know why the de-facto standard definition of isapprox intentionally fails when one of the arguments is zero? isapprox(0.0, 0.0 + 1e-10) # false isapprox(1.0, 1.0 + 1e-10) # true It is clear from the formula…

---

## [An easy way to view system-state when a differential equation solver encounters a warning](https://discourse.julialang.org/t/an-easy-way-to-view-system-state-when-a-differential-equation-solver-encounters-a-warning/118944)

<div class="topic-metadata">

**Author:** [@VBtheHun](https://discourse.julialang.org/u/VBtheHun)\
**Replies:** 4\
**Last updated:** [September 19, 2024, 3:47pm UTC](https://discourse.julialang.org/t/an-easy-way-to-view-system-state-when-a-differential-equation-solver-encounters-a-warning/118944 "2024-09-19T15:47:16Z")

</div>

I am trying to solve a system of differential equations where I run into a larger Maxiters needed warning. I suspect that my model has been ill-specified as this appears only for certain parameter values. To figure this …

---

## [Emulate Enzyme.Const with Zygote](https://discourse.julialang.org/t/emulate-enzyme-const-with-zygote/119594)

<div class="topic-metadata">

**Author:** [@gdalle](https://discourse.julialang.org/u/gdalle)\
**Replies:** 1\
**Last updated:** [September 19, 2024, 3:05pm UTC](https://discourse.julialang.org/t/emulate-enzyme-const-with-zygote/119594 "2024-09-19T15:05:39Z")

</div>

In the next release, DifferentiationInterface.jl will accept constant (non-differentiated) arguments c in addition to the active (differentiated) argument x, I’m wondering how to implement this mechanism optimally for ea…

---

## [ModelingToolkit -- limits to parameter blocks, etc.?](https://discourse.julialang.org/t/modelingtoolkit-limits-to-parameter-blocks-etc/119608)

<div class="topic-metadata">

**Author:** [@BLI](https://discourse.julialang.org/u/BLI)\
**Replies:** 0\
**Last updated:** [September 19, 2024, 2:36pm UTC](https://discourse.julialang.org/t/modelingtoolkit-limits-to-parameter-blocks-etc/119608 "2024-09-19T14:36:39Z")

</div>

Assume I create a ModelingToolkit “instantiator”, say: @mtkmodel Tank begin @structural\_parameters case = :std @parameters begin ... end @variables begin ... end @equations begin ... end end Questions: …

---

## [GLMakie with blocking thread](https://discourse.julialang.org/t/glmakie-with-blocking-thread/119600)

<div class="topic-metadata">

**Author:** [@simonw1](https://discourse.julialang.org/u/simonw1)\
**Replies:** 3\
**Last updated:** [September 19, 2024, 1:56pm UTC](https://discourse.julialang.org/t/glmakie-with-blocking-thread/119600 "2024-09-19T13:56:34Z")

</div>

Hello good people! I am trying to plot and process data in Julia with GLMakie. The data is communicated via a gRPC call and as I am unable to find suitable Julia packages for handling this, I have a python module that h…

---

## [ERROR: Result index of attribute MathOptInterface.VariablePrimal(1) out of bounds. There are currently 0 solution(s) in the model](https://discourse.julialang.org/t/error-result-index-of-attribute-mathoptinterface-variableprimal-1-out-of-bounds-there-are-currently-0-solution-s-in-the-model/119586)

<div class="topic-metadata">

**Author:** [@WuSiren](https://discourse.julialang.org/u/WuSiren)\
**Replies:** 2\
**Last updated:** [September 19, 2024, 9:03am UTC](https://discourse.julialang.org/t/error-result-index-of-attribute-mathoptinterface-variableprimal-1-out-of-bounds-there-are-currently-0-solution-s-in-the-model/119586 "2024-09-19T09:03:46Z")

</div>

ERROR: Result index of attribute MathOptInterface.VariablePrimal(1) out of bounds. There are currently 0 solution(s) in the model. I got this error when solving an MILP model using HiGHS. Do anyone know what it means? T…

---

## [Time differing coefficient ODE](https://discourse.julialang.org/t/time-differing-coefficient-ode/119432)

<div class="topic-metadata">

**Author:** [@gonzalo](https://discourse.julialang.org/u/gonzalo)\
**Replies:** 3\
**Last updated:** [September 19, 2024, 6:50am UTC](https://discourse.julialang.org/t/time-differing-coefficient-ode/119432 "2024-09-19T06:50:24Z")

</div>

Hi everyone, I am wanting to solve the differential equation dx/dt=-x+y; dy/dt=-t\*y+3x x(0)=0; y(0)=1; t(0)=0; note t is a time varying coefficient I tried the subsequent code but I didn’t think it calculate it cor…

---

## [Data Structures for Finite Volumes](https://discourse.julialang.org/t/data-structures-for-finite-volumes/119558)

<div class="topic-metadata">

**Author:** [@afleming](https://discourse.julialang.org/u/afleming)\
**Replies:** 3\
**Last updated:** [September 19, 2024, 6:09am UTC](https://discourse.julialang.org/t/data-structures-for-finite-volumes/119558 "2024-09-19T06:09:29Z")

</div>

I’m working on a (not very sophisticated) finite volume solver for my research, and I’ve run into a perplexing problem around storing the mesh in such a way that minimizes allocations. The basic idea is that every cell …

---

## [MTK simulation allocation free?](https://discourse.julialang.org/t/mtk-simulation-allocation-free/119581)

<div class="topic-metadata">

**Author:** [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Replies:** 1\
**Last updated:** [September 19, 2024, 4:22am UTC](https://discourse.julialang.org/t/mtk-simulation-allocation-free/119581 "2024-09-19T04:22:20Z")

</div>

Is it possible to simulate an MTK model allocation-free? The task is to run a simulation in a control loop with 1ms update interval in real-time.

---

## [Why does OSQP return NaN for convex QP](https://discourse.julialang.org/t/why-does-osqp-return-nan-for-convex-qp/119550)

<div class="topic-metadata">

**Author:** [@blob](https://discourse.julialang.org/u/blob)\
**Replies:** 2\
**Last updated:** [September 19, 2024, 2:33am UTC](https://discourse.julialang.org/t/why-does-osqp-return-nan-for-convex-qp/119550 "2024-09-19T02:33:16Z")

</div>

I have a convex QP: using JuMP, OSQP, Clarabel, Ipopt A = \[0.01; -0.01; 3.548942957597223e-5; -3.548942957597223e-5\] b = \[6.998225528521202; 3.0017744714787984; 6.999996851250971; 3.1487490290693643e-6\] solver = optimi…

---

## [Difficulties writing a program that computes PDEs involving Laplacians with AD](https://discourse.julialang.org/t/difficulties-writing-a-program-that-computes-pdes-involving-laplacians-with-ad/98834)

<div class="topic-metadata">

**Author:** [@Hareruya](https://discourse.julialang.org/u/Hareruya)\
**Replies:** 1\
**Last updated:** [September 19, 2024, 1:51am UTC](https://discourse.julialang.org/t/difficulties-writing-a-program-that-computes-pdes-involving-laplacians-with-ad/98834 "2024-09-19T01:51:24Z")

</div>

Greetings, I have been continuously running into an issue with the usage of AD to calculate the Helmholtz equation and the wave equation. My main area of research is acoustic signal processing, specifically concerning e…

---

## [Tokenising using TextAnalysis 0.8](https://discourse.julialang.org/t/tokenising-using-textanalysis-0-8/119573)

<div class="topic-metadata">

**Author:** [@ablaom](https://discourse.julialang.org/u/ablaom)\
**Replies:** 1\
**Last updated:** [September 19, 2024, 1:21am UTC](https://discourse.julialang.org/t/tokenising-using-textanalysis-0-8/119573 "2024-09-19T01:21:42Z")

</div>

Thanks to the maintainers of TextAnalysis. This works in TextAnalysis 0.7.5, but not here in 0.8.1: julia\> docs = \["Hi my name is Sam.", "How are you today?"\] 2-element Vector{String}: "Hi my name is Sam." "How are y…

---

## [Range Breaks on DateTimeAxis in Makie](https://discourse.julialang.org/t/range-breaks-on-datetimeaxis-in-makie/119334)

<div class="topic-metadata">

**Author:** [@AUK1939](https://discourse.julialang.org/u/AUK1939)\
**Replies:** 6\
**Last updated:** [September 18, 2024, 10:56pm UTC](https://discourse.julialang.org/t/range-breaks-on-datetimeaxis-in-makie/119334 "2024-09-18T22:56:36Z")

</div>

Hi I want to plot the following data. I have the last 3 closing prices from one day and the first 3 closing prices from the next day. 6×2 DataFrame Row │ timestamp close │ DateTime Float6…

---

## [Layout not correct for plotlyjs backend](https://discourse.julialang.org/t/layout-not-correct-for-plotlyjs-backend/119567)

<div class="topic-metadata">

**Author:** [@arw](https://discourse.julialang.org/u/arw)\
**Replies:** 2\
**Last updated:** [September 18, 2024, 6:17pm UTC](https://discourse.julialang.org/t/layout-not-correct-for-plotlyjs-backend/119567 "2024-09-18T18:17:31Z")

</div>

The following code plots two subplots side-by-side. Works fine if you are using the gr backend but does not when using the plotlyjs backend. The first subplot spreads across the whole figure while the second subplot is…

---

## [WAIC computation](https://discourse.julialang.org/t/waic-computation/119553)

<div class="topic-metadata">

**Author:** [@alexten](https://discourse.julialang.org/u/alexten)\
**Replies:** 1\
**Last updated:** [September 18, 2024, 4:04pm UTC](https://discourse.julialang.org/t/waic-computation/119553 "2024-09-18T16:04:53Z")

</div>

I am trying to fill in some gaps left from trying implement model comparison of a model fitted in Turing. Following McElreath’s Statistical Rethinking (2nd ed) and getting help from Claude.ai, I have come up with a funct…

---

## [When is strip\_solution useful?](https://discourse.julialang.org/t/when-is-strip-solution-useful/119517)

<div class="topic-metadata">

**Author:** [@pulk\_jain](https://discourse.julialang.org/u/pulk_jain)\
**Replies:** 6\
**Last updated:** [September 18, 2024, 2:21pm UTC](https://discourse.julialang.org/t/when-is-strip-solution-useful/119517 "2024-09-18T14:21:38Z")

</div>

I was just curious about the use case for strip\_solution. I noticed that my files were too big when saving whole ode solutions using jld2 and whenever I loaded back the file using jldopen, the REPL was riddled with reco…

---

## [What divergence information is available in Turing?](https://discourse.julialang.org/t/what-divergence-information-is-available-in-turing/119246)

<div class="topic-metadata">

**Author:** [@jonask](https://discourse.julialang.org/u/jonask)\
**Replies:** 3\
**Last updated:** [September 18, 2024, 11:52am UTC](https://discourse.julialang.org/t/what-divergence-information-is-available-in-turing/119246 "2024-09-18T11:52:25Z")

</div>

Hi, Semi-new user of Julia and Turing here! I have been using Flux together with Turing to sample from a small NN with NUTS. I have come across different discussions online about where to find information regarding dive…

---

## [Gurobi callback function not accessing / not loading](https://discourse.julialang.org/t/gurobi-callback-function-not-accessing-not-loading/119501)

<div class="topic-metadata">

**Author:** [@cskx](https://discourse.julialang.org/u/cskx)\
**Replies:** 6\
**Last updated:** [September 18, 2024, 10:57am UTC](https://discourse.julialang.org/t/gurobi-callback-function-not-accessing-not-loading/119501 "2024-09-18T10:57:58Z")

</div>

Hello, I would like to access the values during each iterations, then plot the objective function (maybe more info) against iterations, I wrote a callback function as below. I found that my cb\_where is never equal to GR…

---

## [SymbolicRegression: Python -\> Julia?](https://discourse.julialang.org/t/symbolicregression-python-julia/119463)

<div class="topic-metadata">

**Author:** [@BLI](https://discourse.julialang.org/u/BLI)\
**Replies:** 10\
**Last updated:** [September 18, 2024, 10:41am UTC](https://discourse.julialang.org/t/symbolicregression-python-julia/119463 "2024-09-18T10:41:15Z")

</div>

I’m trying to use SymbolicRegression from Julia, based on some \[SRRegressor\] model in Python. Here is the Python model: model\_SK = PySRRegressor( batching=True, niterations=400, model\_selection="accuracy", …

---

## [Optimising allocations and memory use in ODEProblems](https://discourse.julialang.org/t/optimising-allocations-and-memory-use-in-odeproblems/119513)

<div class="topic-metadata">

**Author:** [@markjholmes](https://discourse.julialang.org/u/markjholmes)\
**Replies:** 2\
**Last updated:** [September 18, 2024, 9:14am UTC](https://discourse.julialang.org/t/optimising-allocations-and-memory-use-in-odeproblems/119513 "2024-09-18T09:14:30Z")

</div>

If I have an ODEProblem with many lines of computation going on at each step, when (if ever) does it become sensible to pre-allocate the space for these computations inside the parameters, p? With a simplified example, …

[Previous page](https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=82)

[Next page](https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=84)