# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=437

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

**Page:** 438

---

## [Changing geom color in Gadfly](https://discourse.julialang.org/t/changing-geom-color-in-gadfly/41401)

<div class="topic-metadata">

**Author:** [@EricChameroy](https://discourse.julialang.org/u/EricChameroy)\
**Replies:** 6\
**Last updated:** [June 30, 2020, 9:10pm UTC](https://discourse.julialang.org/t/changing-geom-color-in-gadfly/41401 "2020-06-30T21:10:34Z")

</div>

Hi. I’m trying to change the line color in a graph I’m generating using Gadfly (in a Jupyter notebook). p = plot(Coord.cartesian(xmin=-2, xmax=2, ymin=-2, ymax=2)) for i in 1:50 push!(p, layer(x=d.A, y=prior\_dists.α\[i…

---

## [Evaluation of product of Hermitian functions](https://discourse.julialang.org/t/evaluation-of-product-of-hermitian-functions/42316)

<div class="topic-metadata">

**Author:** [@mleprovost](https://discourse.julialang.org/u/mleprovost)\
**Replies:** 1\
**Last updated:** [June 30, 2020, 8:03pm UTC](https://discourse.julialang.org/t/evaluation-of-product-of-hermitian-functions/42316 "2020-06-30T20:03:35Z")

</div>

Hello, I am working on expansion of a multivariate function f : R^k \\xrightarrow{} R onto a basis of product of univariates Hermite functions: f(x\_1, x\_2, \\ldots, x\_k) = \\sum\_{\\boldsymbol{\\alpha}} c\_{\\boldsymbol{\\alph…

---

## [Set depending of an index](https://discourse.julialang.org/t/set-depending-of-an-index/42322)

<div class="topic-metadata">

**Author:** [@angeloaliano1](https://discourse.julialang.org/u/angeloaliano1)\
**Replies:** 1\
**Last updated:** [June 30, 2020, 7:41pm UTC](https://discourse.julialang.org/t/set-depending-of-an-index/42322 "2020-06-30T19:41:33Z")

</div>

Dear all, I have a constraint in a integer program like @constraint(modelo,\[j in J,i in I\], sum(x\[i,k,h\] for h in H for k in S\_j) \<= 1 ) My problem is how can I write this constraint by using the set S\_j. For exa…

---

## [Nested random effects in MixedModels](https://discourse.julialang.org/t/nested-random-effects-in-mixedmodels/40290)

<div class="topic-metadata">

**Author:** [@talat](https://discourse.julialang.org/u/talat)\
**Replies:** 1\
**Last updated:** [June 30, 2020, 3:50pm UTC](https://discourse.julialang.org/t/nested-random-effects-in-mixedmodels/40290 "2020-06-30T15:50:40Z")

</div>

What is the correct specification of nested random effects in julia’s MixedModels package? What I’m trying to model can be done in R using lme4: y ~ x + (1 | site / block) so that blocks are nested in sites. How would…

---

## [How to build a constraint with summation?](https://discourse.julialang.org/t/how-to-build-a-constraint-with-summation/41618)

<div class="topic-metadata">

**Author:** [@RaquelSantos](https://discourse.julialang.org/u/RaquelSantos)\
**Replies:** 15\
**Last updated:** [June 29, 2020, 9:19pm UTC](https://discourse.julialang.org/t/how-to-build-a-constraint-with-summation/41618 "2020-06-29T21:19:34Z")

</div>

I need to mount this restriction But the following error is appearing when I compile the function: syntax: incomplete: premature end of input I’m doing like this using JuMP, Cbc Model1 = Model(with\_optimizer(Cbc.Op…

---

## [Given that Zygote does not support mutation, how does Recur gets away with it?](https://discourse.julialang.org/t/given-that-zygote-does-not-support-mutation-how-does-recur-gets-away-with-it/36290)

<div class="topic-metadata">

**Author:** [@Azamat](https://discourse.julialang.org/u/Azamat)\
**Replies:** 7\
**Last updated:** [June 29, 2020, 7:59pm UTC](https://discourse.julialang.org/t/given-that-zygote-does-not-support-mutation-how-does-recur-gets-away-with-it/36290 "2020-06-29T19:59:38Z")

</div>

From Flux.jl’s source code here: mutable struct Recur{T} cell::T init state end Recur(m, h = hidden(m)) = Recur(m, h, h) function (m::Recur)(xs...) h, y = m.cell(m.state, xs...) m.state = h return y end i…

---

## [Question regarding TIME\_LIMIT status](https://discourse.julialang.org/t/question-regarding-time-limit-status/42258)

<div class="topic-metadata">

**Author:** [@arkanver](https://discourse.julialang.org/u/arkanver)\
**Replies:** 2\
**Last updated:** [June 29, 2020, 7:09pm UTC](https://discourse.julialang.org/t/question-regarding-time-limit-status/42258 "2020-06-29T19:09:21Z")

</div>

Hi, I am trying to solve some optimization problems using JuMP + CPLEX. Since some problems take a long time I define a time limit of 3600 seconds for my model : model = Model(CPLEX.Optimizer) set\_optimizer\_attribute…

---

## [Batch/batch in Flux?](https://discourse.julialang.org/t/batch-batch-in-flux/41735)

<div class="topic-metadata">

**Author:** [@mefob](https://discourse.julialang.org/u/mefob)\
**Replies:** 2\
**Last updated:** [June 29, 2020, 2:04pm UTC](https://discourse.julialang.org/t/batch-batch-in-flux/41735 "2020-06-29T14:04:09Z")

</div>

I am building my own ODE layer and would like to make sure it works with batches as well as with individual vectors. The input and output to my layer are a NxM 2D arrays, so I will also need to reshape to couple e.g. t…

---

## [Cummulative death by day by country](https://discourse.julialang.org/t/cummulative-death-by-day-by-country/42080)

<div class="topic-metadata">

**Author:** [@Chen](https://discourse.julialang.org/u/Chen)\
**Replies:** 29\
**Last updated:** [June 29, 2020, 1:45pm UTC](https://discourse.julialang.org/t/cummulative-death-by-day-by-country/42080 "2020-06-29T13:45:25Z")

</div>

In R, one would use tidyverse to, for example, aggregate daily deaths of COVID-19 by day and by country \[0\]. How would one do it in Julia? Is there a package that is similar to R’s tidyverse? Or does one write a couple …

---

## [Contributing to packages](https://discourse.julialang.org/t/contributing-to-packages/42216)

<div class="topic-metadata">

**Author:** [@bojohnson02](https://discourse.julialang.org/u/bojohnson02)\
**Replies:** 5\
**Last updated:** [June 29, 2020, 1:43pm UTC](https://discourse.julialang.org/t/contributing-to-packages/42216 "2020-06-29T13:43:05Z")

</div>

I’m working on adding a distribution to Distributions.jl and am curious how to get a good workflow for making contributions. I first created a new environment with \]activate MyDist, added Distributions.jl and the other n…

---

## [Issue with Callbacks When Solving Differential Equations Having Dual Number States](https://discourse.julialang.org/t/issue-with-callbacks-when-solving-differential-equations-having-dual-number-states/41883)

<div class="topic-metadata">

**Author:** [@tomaklutfu](https://discourse.julialang.org/u/tomaklutfu)\
**Replies:** 7\
**Last updated:** [June 29, 2020, 1:25pm UTC](https://discourse.julialang.org/t/issue-with-callbacks-when-solving-differential-equations-having-dual-number-states/41883 "2020-06-29T13:25:44Z")

</div>

When I solve the same ODE with callback to stop simulation early and without callback, I get different partials at the same time not even close. I believe that adding callback introduces dual times and, at the event time…

---

## [Julia: NLsolve providing different solution each run and sometimes returns NaN?](https://discourse.julialang.org/t/julia-nlsolve-providing-different-solution-each-run-and-sometimes-returns-nan/42191)

<div class="topic-metadata">

**Author:** [@RasmusDamgaard](https://discourse.julialang.org/u/RasmusDamgaard)\
**Replies:** 1\
**Last updated:** [June 29, 2020, 10:54am UTC](https://discourse.julialang.org/t/julia-nlsolve-providing-different-solution-each-run-and-sometimes-returns-nan/42191 "2020-06-29T10:54:01Z")

</div>

Hi, Note: I have cross-posted this to stackexchange: optimization - Julia: NLsolve providing different solution each run and sometimes returns NaN? - Stack Overflow I am trying to replicate some matlab code as a part o…

---

## [An Idea for Optimization as if Solving ODE](https://discourse.julialang.org/t/an-idea-for-optimization-as-if-solving-ode/42195)

<div class="topic-metadata">

**Author:** [@tomaklutfu](https://discourse.julialang.org/u/tomaklutfu)\
**Replies:** 25\
**Last updated:** [June 29, 2020, 4:39am UTC](https://discourse.julialang.org/t/an-idea-for-optimization-as-if-solving-ode/42195 "2020-06-29T04:39:50Z")

</div>

There are plenty of methods to solve a minimization problem. Many of them iteratively solves for the parameters by decrementing them by a fraction (determined by a learning rate) of the partial derivatives of the objecti…

---

## ["UndefVarError: with\_optimizer not defined" using GLPK](https://discourse.julialang.org/t/undefvarerror-with-optimizer-not-defined-using-glpk/42220)

<div class="topic-metadata">

**Author:** [@Ernesto\_Diaz](https://discourse.julialang.org/u/Ernesto_Diaz)\
**Replies:** 6\
**Last updated:** [June 29, 2020, 3:35am UTC](https://discourse.julialang.org/t/undefvarerror-with-optimizer-not-defined-using-glpk/42220 "2020-06-29T03:35:29Z")

</div>

I have JuMP v.0.18.6 . I think the message “UndefVarError: with\_optimizer not defined” is showed because I need JuMP v.0.19, but when I wrote Pkg.update(“JuMP”) JuMP wasn´t update.

---

## [LIBSVM crashes after sucessfully running a few times](https://discourse.julialang.org/t/libsvm-crashes-after-sucessfully-running-a-few-times/42047)

<div class="topic-metadata">

**Author:** [@rio](https://discourse.julialang.org/u/rio)\
**Replies:** 1\
**Last updated:** [June 29, 2020, 1:25am UTC](https://discourse.julialang.org/t/libsvm-crashes-after-sucessfully-running-a-few-times/42047 "2020-06-29T01:25:52Z")

</div>

Hi, I am using LIBSVM.jl to train a SVM classification model. Apparently the model in my code below trains successfully. However, after running it a few times it crashes (after about 10 repetitions). It shows a segmenta…

---

## [A question ahout PCA](https://discourse.julialang.org/t/a-question-ahout-pca/42100)

<div class="topic-metadata">

**Author:** [@abcde](https://discourse.julialang.org/u/abcde)\
**Replies:** 9\
**Last updated:** [June 29, 2020, 1:04am UTC](https://discourse.julialang.org/t/a-question-ahout-pca/42100 "2020-06-29T01:04:23Z")

</div>

After applying PCA algorithm, how to display its principal component?thanks!!

---

## [Help speeding up finite horizon dynamic programming problem](https://discourse.julialang.org/t/help-speeding-up-finite-horizon-dynamic-programming-problem/22782)

<div class="topic-metadata">

**Author:** [@amrods](https://discourse.julialang.org/u/amrods)\
**Replies:** 33\
**Last updated:** [June 29, 2020, 12:50am UTC](https://discourse.julialang.org/t/help-speeding-up-finite-horizon-dynamic-programming-problem/22782 "2020-06-29T00:50:01Z")

</div>

I am struggling to speed up the computation of solutions for a finite horizon dynamic programming problem. I am using interpolation to avoid computing the value function outside of points in the grid. Right now it takes …

---

## [Volcano - HPC workloads on Kubernetes](https://discourse.julialang.org/t/volcano-hpc-workloads-on-kubernetes/42187)

<div class="topic-metadata">

**Author:** [@johnh](https://discourse.julialang.org/u/johnh)\
**Replies:** 1\
**Last updated:** [June 28, 2020, 11:05am UTC](https://discourse.julialang.org/t/volcano-hpc-workloads-on-kubernetes/42187 "2020-06-28T11:05:25Z")

</div>

I have not tried this but I like the concept. with Kubernetes being more and more deployed has anyone workedon Julia in such an environment? What do we think of the Volcano project as a way of running Julia in paralle…

---

## [Distributed startup on large clusters](https://discourse.julialang.org/t/distributed-startup-on-large-clusters/42186)

<div class="topic-metadata">

**Author:** [@johnh](https://discourse.julialang.org/u/johnh)\
**Replies:** 0\
**Last updated:** [June 28, 2020, 5:21am UTC](https://discourse.julialang.org/t/distributed-startup-on-large-clusters/42186 "2020-06-28T05:21:27Z")

</div>

I note that in Julia 1.5 IPV6 is supported for launch\_on\_machine(). Which is a good thing. https://github.com/JuliaLang/julia/pull/34430 This leads me to revive and old topic. Julia uses ssh connections to start proce…

---

## [Reading large-columned data using Feather.jl is too slow](https://discourse.julialang.org/t/reading-large-columned-data-using-feather-jl-is-too-slow/40377)

<div class="topic-metadata">

**Author:** [@Jean](https://discourse.julialang.org/u/Jean)\
**Replies:** 8\
**Last updated:** [June 28, 2020, 4:09am UTC](https://discourse.julialang.org/t/reading-large-columned-data-using-feather-jl-is-too-slow/40377 "2020-06-28T04:09:07Z")

</div>

Hi, I am working with large-columned data sets. One small example is the dimension of (1452, 66584) whose data size is about 2GB. When it converted to a feather format, its size was down to 778MB. The problem is Feathe…

---

## [Should I re-train the neural network if the desired final state is changed while solving optimal control problem?](https://discourse.julialang.org/t/should-i-re-train-the-neural-network-if-the-desired-final-state-is-changed-while-solving-optimal-control-problem/42166)

<div class="topic-metadata">

**Author:** [@XiaodongMa-MRI](https://discourse.julialang.org/u/XiaodongMa-MRI)\
**Replies:** 3\
**Last updated:** [June 28, 2020, 3:19am UTC](https://discourse.julialang.org/t/should-i-re-train-the-neural-network-if-the-desired-final-state-is-changed-while-solving-optimal-control-problem/42166 "2020-06-28T03:19:50Z")

</div>

Hi everyone, I have a very basic question about solving optimal control problems with universal differential equations. Say I want to find a control c(t) to achieve a certain final state u(T), and I can use neural netwo…

---

## [How do you push to production?](https://discourse.julialang.org/t/how-do-you-push-to-production/42175)

<div class="topic-metadata">

**Author:** [@MarkovChains](https://discourse.julialang.org/u/MarkovChains)\
**Replies:** 2\
**Last updated:** [June 27, 2020, 11:26pm UTC](https://discourse.julialang.org/t/how-do-you-push-to-production/42175 "2020-06-27T23:26:16Z")

</div>

So, when I write some algorithm for processing data in R, after testing, the act of pushing it to production is usually little more than basically having a pre-existing application or process call the R script. But, sin…

---

## [Gurobi on Julia 1.4](https://discourse.julialang.org/t/gurobi-on-julia-1-4/42131)

<div class="topic-metadata">

**Author:** [@SingingKim](https://discourse.julialang.org/u/SingingKim)\
**Replies:** 9\
**Last updated:** [June 27, 2020, 8:35pm UTC](https://discourse.julialang.org/t/gurobi-on-julia-1-4/42131 "2020-06-27T20:35:48Z")

</div>

I’m trying to upgrade Julia to 1.4 from 1.3, but Gurobi package is giving me the following error. Could anybody confirm whether it’s related to my own setting or not? Any comments would be appreciated. I only have thre…

---

## [Rewriting JuMP code in MathOptInterface](https://discourse.julialang.org/t/rewriting-jump-code-in-mathoptinterface/42061)

<div class="topic-metadata">

**Author:** [@GeneralPoxter](https://discourse.julialang.org/u/GeneralPoxter)\
**Replies:** 5\
**Last updated:** [June 27, 2020, 4:59pm UTC](https://discourse.julialang.org/t/rewriting-jump-code-in-mathoptinterface/42061 "2020-06-27T16:59:32Z")

</div>

Say I wanted to add a variable x which represents an m x n matrix whose elements are constrianed. In JuMP, the code would simply be: @variable(model, 0 \<= x\[i=1:m, j=1:n\] \<= 1) However, I am not sure how to translate …

---

## [Component based modelling with ModelingToolkit.jl](https://discourse.julialang.org/t/component-based-modelling-with-modelingtoolkit-jl/41116)

<div class="topic-metadata">

**Author:** [@ohmsweetohm1](https://discourse.julialang.org/u/ohmsweetohm1)\
**Replies:** 1\
**Last updated:** [June 27, 2020, 3:59am UTC](https://discourse.julialang.org/t/component-based-modelling-with-modelingtoolkit-jl/41116 "2020-06-27T03:59:15Z")

</div>

I want to model a simple heating system using ModelingToolkit.jl. It consists of a thermal storage, a boiler and a heat consumer. The following equations govern this model. Thermal Storage The thermal storage has one …

---

## [Conjugate Gradient optimization with set of functions](https://discourse.julialang.org/t/conjugate-gradient-optimization-with-set-of-functions/42070)

<div class="topic-metadata">

**Author:** [@sergevic](https://discourse.julialang.org/u/sergevic)\
**Replies:** 9\
**Last updated:** [June 27, 2020, 3:40am UTC](https://discourse.julialang.org/t/conjugate-gradient-optimization-with-set-of-functions/42070 "2020-06-27T03:40:20Z")

</div>

This post is related to a previous post of mine and I prefered to expose the problem separatey. I have to optimize a set of functions with conjugate gradient optimization, but I have to define the whole set of functions …

---

## [Illegal CPU instructions when testing GDAL.jl?](https://discourse.julialang.org/t/illegal-cpu-instructions-when-testing-gdal-jl/41922)

<div class="topic-metadata">

**Author:** [@Chen](https://discourse.julialang.org/u/Chen)\
**Replies:** 18\
**Last updated:** [June 26, 2020, 10:35pm UTC](https://discourse.julialang.org/t/illegal-cpu-instructions-when-testing-gdal-jl/41922 "2020-06-26T22:35:42Z")

</div>

Does GDAL come with prebuilt x86\_64 libraries? If yes, it seems that the libraries were built with march that is not x86-64. On my old Pentium 4 CPU, Julia gives an error. I think the error was caused by a CPU instruct…

---

## [Need HTTP.WebSockets documentation](https://discourse.julialang.org/t/need-http-websockets-documentation/39237)

<div class="topic-metadata">

**Author:** [@Laszlo\_Nagy](https://discourse.julialang.org/u/Laszlo_Nagy)\
**Replies:** 0\
**Last updated:** [May 10, 2020, 6:27pm UTC](https://discourse.julialang.org/t/need-http-websockets-documentation/39237 "2020-05-10T18:27:31Z")

</div>

Hello, I’m trying to do something useful with websockets. I’m unable to find its documentation. julia\> import HTTP.WebSockets help?\> HTTP.WebSockets No documentation found. No docstring found for module HTTP.WebSo…

---

## [Two questions about axises for matrix plot](https://discourse.julialang.org/t/two-questions-about-axises-for-matrix-plot/41972)

<div class="topic-metadata">

**Author:** [@Torkel](https://discourse.julialang.org/u/Torkel)\
**Replies:** 2\
**Last updated:** [June 26, 2020, 7:47pm UTC](https://discourse.julialang.org/t/two-questions-about-axises-for-matrix-plot/41972 "2020-06-26T19:47:49Z")

</div>

I have this code plot(1:20,1:20,rand(RGB{Float64}, 20, 20)) Here the y-axis goes from top to bottom, and the x-axis from left to right. But what if I want both to start from the bottom left corner? I can easily transfo…

---

## [Gcc vs Threads.@threads vs Threads.@spawn for large loops](https://discourse.julialang.org/t/gcc-vs-threads-threads-vs-threads-spawn-for-large-loops/34273)

<div class="topic-metadata">

**Author:** [@j-fu](https://discourse.julialang.org/u/j-fu)\
**Replies:** 14\
**Last updated:** [June 26, 2020, 7:45pm UTC](https://discourse.julialang.org/t/gcc-vs-threads-threads-vs-threads-spawn-for-large-loops/34273 "2020-06-26T19:45:03Z")

</div>

Hi, Schönauer vector triad again, see also the benchmarking site of Georg Hager. This time we compare multithreading vs. scalar, and also compare to gcc. Here ist the generating code. We see that for scalar perform…

[Previous page](https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=436)

[Next page](https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=438)