# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=365

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

**Page:** 366

---

## [Jointly simulate high, low, and terminal value of Brownian motion](https://discourse.julialang.org/t/jointly-simulate-high-low-and-terminal-value-of-brownian-motion/61075)

<div class="topic-metadata">

**Author:** [@Beliavsky](https://discourse.julialang.org/u/Beliavsky)\
**Replies:** 3\
**Last updated:** [May 17, 2021, 4:00pm UTC](https://discourse.julialang.org/t/jointly-simulate-high-low-and-terminal-value-of-brownian-motion/61075 "2021-05-17T16:00:43Z")

</div>

You can simulate the terminal value of a 1D Brownian motion using a Gaussian random number generator, randn in Julia. For some problems you would like to simulate the maximum and minimum in addition to the terminal value…

---

## [X-axis at center of plot](https://discourse.julialang.org/t/x-axis-at-center-of-plot/24015)

<div class="topic-metadata">

**Author:** [@rakeshvar](https://discourse.julialang.org/u/rakeshvar)\
**Replies:** 4\
**Last updated:** [May 17, 2021, 12:12pm UTC](https://discourse.julialang.org/t/x-axis-at-center-of-plot/24015 "2021-05-17T12:12:33Z")

</div>

I want the x-axis to be at the center (y=0) but it is coming out at the bottom. using Plots plotly() plot(\[-1, 0, 1\], line=(:stem, 2), m=(:red, 3), xticks=1:3, xmirror=true, yaxis=false)

---

## [Flux.params of a matrix implemented as a struct](https://discourse.julialang.org/t/flux-params-of-a-matrix-implemented-as-a-struct/60787)

<div class="topic-metadata">

**Author:** [@Tomas\_Pevny](https://discourse.julialang.org/u/Tomas_Pevny)\
**Replies:** 11\
**Last updated:** [May 17, 2021, 7:09am UTC](https://discourse.julialang.org/t/flux-params-of-a-matrix-implemented-as-a-struct/60787 "2021-05-17T07:09:16Z")

</div>

Dear All, I have a student who is implementing few algorithms for distributed optimization (training of neural networks) using Flux / Zygote tooling. We have been tracking various sources of inefficiencies and I have f…

---

## [Can't get the same results at the rocket control tutorial in JuMP](https://discourse.julialang.org/t/cant-get-the-same-results-at-the-rocket-control-tutorial-in-jump/61235)

<div class="topic-metadata">

**Author:** [@yucho147](https://discourse.julialang.org/u/yucho147)\
**Replies:** 4\
**Last updated:** [May 17, 2021, 12:08am UTC](https://discourse.julialang.org/t/cant-get-the-same-results-at-the-rocket-control-tutorial-in-jump/61235 "2021-05-17T00:08:35Z")

</div>

Hi I am learning how to use the JuMP package. However, I am not getting the same results from the rocket control tutorial. https://jump.dev/JuMP.jl/v0.21.8/tutorials/Nonlinear%20programs/rocket\_control/ In my environm…

---

## [How to convert TOML file into a Structure and vice versa?](https://discourse.julialang.org/t/how-to-convert-toml-file-into-a-structure-and-vice-versa/61265)

<div class="topic-metadata">

**Author:** [@JosephPollacco](https://discourse.julialang.org/u/JosephPollacco)\
**Replies:** 1\
**Last updated:** [May 16, 2021, 11:22pm UTC](https://discourse.julialang.org/t/how-to-convert-toml-file-into-a-structure-and-vice-versa/61265 "2021-05-16T23:22:14Z")

</div>

Hi I have a large SoilWater-ToolBox model and I have got all the input , Parameters, as a mutable struct. In order to create a package I will need to read the parameters outside the model as recommended in previous post …

---

## [What recommended format of input parameters/options of a large hydrological model compiled as a Julia Package?](https://discourse.julialang.org/t/what-recommended-format-of-input-parameters-options-of-a-large-hydrological-model-compiled-as-a-julia-package/60561)

<div class="topic-metadata">

**Author:** [@JosephPollacco](https://discourse.julialang.org/u/JosephPollacco)\
**Replies:** 2\
**Last updated:** [May 16, 2021, 10:59pm UTC](https://discourse.julialang.org/t/what-recommended-format-of-input-parameters-options-of-a-large-hydrological-model-compiled-as-a-julia-package/60561 "2021-05-16T22:59:55Z")

</div>

The question is what format (e.g. .csv, .txt etc…) would you recommend to read Inputs options/ parameters values of a large model https://github.com/manaakiwhenua/SoilWater\_ToolBox.git ? I was informed in Discourse that…

---

## [Gadfly: Color Coding a Simple Bar Chart](https://discourse.julialang.org/t/gadfly-color-coding-a-simple-bar-chart/61211)

<div class="topic-metadata">

**Author:** [@ben-schulz](https://discourse.julialang.org/u/ben-schulz)\
**Replies:** 2\
**Last updated:** [May 16, 2021, 4:19pm UTC](https://discourse.julialang.org/t/gadfly-color-coding-a-simple-bar-chart/61211 "2021-05-16T16:19:56Z")

</div>

suppose i’m working in a Jupyter notebook with a Julia kernel, and i want to plot some very simple data in a bar chart, to show the proportion of two quantities A and B, like so: # Julia 1.6.1 using Gadfly p = plot(x=\[…

---

## [Constraint declaration generates an error](https://discourse.julialang.org/t/constraint-declaration-generates-an-error/61239)

<div class="topic-metadata">

**Author:** [@mamo](https://discourse.julialang.org/u/mamo)\
**Replies:** 6\
**Last updated:** [May 16, 2021, 3:16pm UTC](https://discourse.julialang.org/t/constraint-declaration-generates-an-error/61239 "2021-05-16T15:16:34Z")

</div>

Dear all, how to type the constraint below in order to avoid an error. for j in N1 if j\>1 && j\<7 @constraint(vrpm, sum(x\[j,i,k\] for i in N5, k in B if i!=j) -sum(x\[i,j,k\] for i in N4, k in B, if i!=j) == 0) end en…

---

## [Solving System of nonlinear Equations using ModelingToolkit.jl and NonlinearSolve.jl](https://discourse.julialang.org/t/solving-system-of-nonlinear-equations-using-modelingtoolkit-jl-and-nonlinearsolve-jl/59096)

<div class="topic-metadata">

**Author:** [@wst](https://discourse.julialang.org/u/wst)\
**Replies:** 7\
**Last updated:** [May 16, 2021, 10:14am UTC](https://discourse.julialang.org/t/solving-system-of-nonlinear-equations-using-modelingtoolkit-jl-and-nonlinearsolve-jl/59096 "2021-05-16T10:14:18Z")

</div>

Hey there, I’m fairly new to Julia and this forum (in fact my first post here). About my problem: I’m currently trying to solve a system of 3 nonlinear equations that emerged as the solution of the hanging chain probl…

---

## [Please tell me about the following Turing.jl processing](https://discourse.julialang.org/t/please-tell-me-about-the-following-turing-jl-processing/61202)

<div class="topic-metadata">

**Author:** [@anon20242138](https://discourse.julialang.org/u/anon20242138)\
**Replies:** 1\
**Last updated:** [May 15, 2021, 5:37pm UTC](https://discourse.julialang.org/t/please-tell-me-about-the-following-turing-jl-processing/61202 "2021-05-15T17:37:37Z")

</div>

What does the following process mean? What does “Observe each prediction.” mean? This code from Turing tutorials ( https://turing.ml/dev/tutorials/3-bayesnn/ ) for i = 1:length(ts) ts\[i\] ~ Bernoulli(preds\[i\]) end

---

## [Gadfly Title Size](https://discourse.julialang.org/t/gadfly-title-size/61168)

<div class="topic-metadata">

**Author:** [@white-c](https://discourse.julialang.org/u/white-c)\
**Replies:** 4\
**Last updated:** [May 15, 2021, 4:30am UTC](https://discourse.julialang.org/t/gadfly-title-size/61168 "2021-05-15T04:30:29Z")

</div>

I want to have a different font size for a Gadfly Guide.title() versus Guide.xlabel(). Setting major\_label\_font\_size affects both. How do I control the title size separately?

---

## [POST results of multiple checkbox selections](https://discourse.julialang.org/t/post-results-of-multiple-checkbox-selections/61179)

<div class="topic-metadata">

**Author:** [@fyzycyst](https://discourse.julialang.org/u/fyzycyst)\
**Replies:** 1\
**Last updated:** [May 14, 2021, 11:03pm UTC](https://discourse.julialang.org/t/post-results-of-multiple-checkbox-selections/61179 "2021-05-14T23:03:17Z")

</div>

What I’m attempting: There’s a site (NASA ModelWeb) where one can access online models for Earth’s atmosphere (among many other models). I’m writing code to access this to create an atmospheric profile \[number density o…

---

## [Why is this dataframe filter slow?](https://discourse.julialang.org/t/why-is-this-dataframe-filter-slow/61177)

<div class="topic-metadata">

**Author:** [@Iulian.Cioarca](https://discourse.julialang.org/u/Iulian.Cioarca)\
**Replies:** 5\
**Last updated:** [May 14, 2021, 9:57pm UTC](https://discourse.julialang.org/t/why-is-this-dataframe-filter-slow/61177 "2021-05-14T21:57:49Z")

</div>

I need to extract rows from a dataframe based on values of a specific column. I tried to use filter but it’s slower than traditional findall. Am I missing something? df = DataFrame(a=\["a", "b", "c"\], b=\[1,2,3\]) @elapse…

---

## [Linsolve on SparseMatrixCSC{BigFloat}](https://discourse.julialang.org/t/linsolve-on-sparsematrixcsc-bigfloat/60742)

<div class="topic-metadata">

**Author:** [@MatFi](https://discourse.julialang.org/u/MatFi)\
**Replies:** 2\
**Last updated:** [May 14, 2021, 7:50am UTC](https://discourse.julialang.org/t/linsolve-on-sparsematrixcsc-bigfloat/60742 "2021-05-14T07:50:13Z")

</div>

I want to solve a quite large but sparse DAE system using DifferentialEquaitions.jl I can do it with decent efficiency when using Float64’s Now I would like to do the same thing with higher precision numbers (Double64,…

---

## [How do I to transform mapreduce function to work well with CUDA?](https://discourse.julialang.org/t/how-do-i-to-transform-mapreduce-function-to-work-well-with-cuda/61084)

<div class="topic-metadata">

**Author:** [@Noel\_Araujo](https://discourse.julialang.org/u/Noel_Araujo)\
**Replies:** 5\
**Last updated:** [May 14, 2021, 9:00pm UTC](https://discourse.julialang.org/t/how-do-i-to-transform-mapreduce-function-to-work-well-with-cuda/61084 "2021-05-14T21:00:00Z")

</div>

Hellos I’m playing with CUDA.jl, and I just wish to perform a mapreduce faster. Here a minimal code: using CUDA using LinearAlgebra x = 100 N = ((x^2)÷2 - x÷2) n\_hat = rand(3) A = rand(3,N) b = rand(N) for p=1:10 …

---

## [Makie not passing all tests after update](https://discourse.julialang.org/t/makie-not-passing-all-tests-after-update/61135)

<div class="topic-metadata">

**Author:** [@diogoribeiro98](https://discourse.julialang.org/u/diogoribeiro98)\
**Replies:** 2\
**Last updated:** [May 14, 2021, 1:30pm UTC](https://discourse.julialang.org/t/makie-not-passing-all-tests-after-update/61135 "2021-05-14T13:30:59Z")

</div>

I just updated Makie and it stopped passing all tests. I am unable to use popup windows and I can’t seem to get it working. Here is the test result: (@v1.5) pkg\> test GLMakie Testing GLMakie Status \`C:\\Users\\diogo…

---

## [Optimising a non-linear user-defined function using NLopt](https://discourse.julialang.org/t/optimising-a-non-linear-user-defined-function-using-nlopt/61141)

<div class="topic-metadata">

**Author:** [@Debasish](https://discourse.julialang.org/u/Debasish)\
**Replies:** 5\
**Last updated:** [May 14, 2021, 1:21pm UTC](https://discourse.julialang.org/t/optimising-a-non-linear-user-defined-function-using-nlopt/61141 "2021-05-14T13:21:34Z")

</div>

Dear Julia experts, This is my second Julia code. I have a physical problem to solve in which a waving filament in fluid medium propels itself (think of a beating sperm tail). I have a MATLAB code which optimises the s…

---

## [Fixing vs Constraining a variable in JuMP](https://discourse.julialang.org/t/fixing-vs-constraining-a-variable-in-jump/27609)

<div class="topic-metadata">

**Author:** [@Libbum](https://discourse.julialang.org/u/Libbum)\
**Replies:** 13\
**Last updated:** [May 14, 2021, 11:10am UTC](https://discourse.julialang.org/t/fixing-vs-constraining-a-variable-in-jump/27609 "2021-05-14T11:10:13Z")

</div>

I was wondering if someone could explain the differences between fixing and constraining a variable in a little more detail than the JuMP documentation does. If you use fix(...; force=true); my understanding is that thi…

---

## [Confusion about parameter interpretation in Turing documentation](https://discourse.julialang.org/t/confusion-about-parameter-interpretation-in-turing-documentation/54655)

<div class="topic-metadata">

**Author:** [@zenkavi](https://discourse.julialang.org/u/zenkavi)\
**Replies:** 10\
**Last updated:** [May 14, 2021, 3:36am UTC](https://discourse.julialang.org/t/confusion-about-parameter-interpretation-in-turing-documentation/54655 "2021-05-14T03:36:16Z")

</div>

In the Inference of a SDE section og the Turing tutorials the noise added to the states are described in the noise model with the \\phi parameters. Is \\sigma supposed to capture observation noise? What is its true value?

---

## [I might have missed this but why is \`head(df::AbstractDataFrame)\` deprecated?](https://discourse.julialang.org/t/i-might-have-missed-this-but-why-is-head-df-abstractdataframe-deprecated/27988)

<div class="topic-metadata">

**Author:** [@xiaodai](https://discourse.julialang.org/u/xiaodai)\
**Replies:** 52\
**Last updated:** [May 13, 2021, 9:08pm UTC](https://discourse.julialang.org/t/i-might-have-missed-this-but-why-is-head-df-abstractdataframe-deprecated/27988 "2021-05-13T21:08:32Z")

</div>

head seems to be terminology used everywhere including R and Pandas, so why deprecate it?

---

## [Julia packages for Multiscale Modelling of Multicellular Tissues?](https://discourse.julialang.org/t/julia-packages-for-multiscale-modelling-of-multicellular-tissues/61067)

<div class="topic-metadata">

**Author:** [@SteffenPL](https://discourse.julialang.org/u/SteffenPL)\
**Replies:** 4\
**Last updated:** [May 13, 2021, 8:31pm UTC](https://discourse.julialang.org/t/julia-packages-for-multiscale-modelling-of-multicellular-tissues/61067 "2021-05-13T20:31:13Z")

</div>

I’m using Julia to program multicellular simulations. It’s working well and the simulations are very fast, but basically I was never able to use other packages in the core of my simulations. I read this preprint: whi…

---

## [Converting a toy example to DifferentialEquations](https://discourse.julialang.org/t/converting-a-toy-example-to-differentialequations/61070)

<div class="topic-metadata">

**Author:** [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Replies:** 16\
**Last updated:** [May 13, 2021, 5:16pm UTC](https://discourse.julialang.org/t/converting-a-toy-example-to-differentialequations/61070 "2021-05-13T17:16:23Z")

</div>

I am trying to convert the following Python example to Julia: """ Tutorial example showing how to use the implicit solver RADAU. It simulates a falling mass. """ import numpy as np import pylab as plt from assimulo.pro…

---

## [Makie - How to choose alignment of an axis that does not fill its allocated layout](https://discourse.julialang.org/t/makie-how-to-choose-alignment-of-an-axis-that-does-not-fill-its-allocated-layout/60725)

<div class="topic-metadata">

**Author:** [@Kolaru](https://discourse.julialang.org/u/Kolaru)\
**Replies:** 3\
**Last updated:** [May 13, 2021, 3:08pm UTC](https://discourse.julialang.org/t/makie-how-to-choose-alignment-of-an-axis-that-does-not-fill-its-allocated-layout/60725 "2021-05-13T15:08:54Z")

</div>

When choosing DataAspect for an axis and setting the limits manually, it is not uncommon for an axis to not fill all the space at its disposition. As far as I know this is unavoidable since in this case the aspect ratio …

---

## [Makie - Inset axes and their drawing order](https://discourse.julialang.org/t/makie-inset-axes-and-their-drawing-order/60987)

<div class="topic-metadata">

**Author:** [@Kolaru](https://discourse.julialang.org/u/Kolaru)\
**Replies:** 5\
**Last updated:** [May 13, 2021, 2:42pm UTC](https://discourse.julialang.org/t/makie-inset-axes-and-their-drawing-order/60987 "2021-05-13T14:42:47Z")

</div>

If I understand correctly inset axes can be create rather easily in Makie by putting multiple axes in the same layout position. Something as follow: fig = Figure(resolution=(500, 500)) # The main axis density\_ax = Axis…

---

## [ODEFunction throwing "ERROR: LoadError: mul\_float: types of a and b must match"](https://discourse.julialang.org/t/odefunction-throwing-error-loaderror-mul-float-types-of-a-and-b-must-match/61024)

<div class="topic-metadata">

**Author:** [@ap2013](https://discourse.julialang.org/u/ap2013)\
**Replies:** 5\
**Last updated:** [May 13, 2021, 12:04pm UTC](https://discourse.julialang.org/t/odefunction-throwing-error-loaderror-mul-float-types-of-a-and-b-must-match/61024 "2021-05-13T12:04:38Z")

</div>

What does the following error mean: “ERROR: LoadError: mul\_float: types of a and b must match”? I am running a code that repeatedly calls a function that creates an ODE problem and solves it. The function is called in a…

---

## [Animate with While loop in Julia](https://discourse.julialang.org/t/animate-with-while-loop-in-julia/61069)

<div class="topic-metadata">

**Author:** [@Minimum-Pollution-96](https://discourse.julialang.org/u/Minimum-Pollution-96)\
**Replies:** 4\
**Last updated:** [May 13, 2021, 10:27am UTC](https://discourse.julialang.org/t/animate-with-while-loop-in-julia/61069 "2021-05-13T10:27:24Z")

</div>

Is it possible to implement plot animation within while loop in Julia? I’m trying to translate a code that my professor gave me in Matlab. (Top Opt - Sigmund 99 line matlab code) It seems both @gif and @animate support …

---

## [CairoMakie AssertionError: length(positions) == length(colors) when trying to record](https://discourse.julialang.org/t/cairomakie-assertionerror-length-positions-length-colors-when-trying-to-record/61001)

<div class="topic-metadata">

**Author:** [@aramirezreyes](https://discourse.julialang.org/u/aramirezreyes)\
**Replies:** 2\
**Last updated:** [May 13, 2021, 3:56am UTC](https://discourse.julialang.org/t/cairomakie-assertionerror-length-positions-length-colors-when-trying-to-record/61001 "2021-05-13T03:56:41Z")

</div>

Hi, I’ve been trying to make this code run but I don’t know how to fix a problem. I think the problem happens too deep in the stack call that I just cannot find where in particular is it occurring: My goal is to have an…

---

## [Counting non negative instances of a variable for use in constraint - efficient formulation?](https://discourse.julialang.org/t/counting-non-negative-instances-of-a-variable-for-use-in-constraint-efficient-formulation/60507)

<div class="topic-metadata">

**Author:** [@gobs](https://discourse.julialang.org/u/gobs)\
**Replies:** 6\
**Last updated:** [May 13, 2021, 5:58am UTC](https://discourse.julialang.org/t/counting-non-negative-instances-of-a-variable-for-use-in-constraint-efficient-formulation/60507 "2021-05-13T05:58:21Z")

</div>

This is an optimisation and not JuMP related question, but I thought it worth asking here. I have a constraint in my model which limits the number of non-negative instances of a variable. Specifically, I have a power bal…

---

## [Fill gaps in DataFrame](https://discourse.julialang.org/t/fill-gaps-in-dataframe/60912)

<div class="topic-metadata">

**Author:** [@stej](https://discourse.julialang.org/u/stej)\
**Replies:** 10\
**Last updated:** [May 13, 2021, 5:32am UTC](https://discourse.julialang.org/t/fill-gaps-in-dataframe/60912 "2021-05-13T05:32:12Z")

</div>

What is an idiomatic way how to fill gaps in DataFrame? “Gaps” for me are some unknown data. One example is - I need to draw a line, but I have values only for some points. I need to supply some values (e.g. zero) for th…

---

## [Getting started with Differential Equations](https://discourse.julialang.org/t/getting-started-with-differential-equations/61055)

<div class="topic-metadata">

**Author:** [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Replies:** 7\
**Last updated:** [May 13, 2021, 1:25am UTC](https://discourse.julialang.org/t/getting-started-with-differential-equations/61055 "2021-05-13T01:25:36Z")

</div>

I am trying to port a simple example from Python to Julia, but already the first example from the Tutorial fails: using DifferentialEquations function lorenz(t, u, du) du\[1\] = 10.0(u\[2\]-u\[1\]) du\[2\] = u\[1\]\*(28.0…

[Previous page](https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=364)

[Next page](https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=366)