# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1741

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

**Page:** 1742

---

## [Having trouble figuring out which line the error is in](https://discourse.julialang.org/t/having-trouble-figuring-out-which-line-the-error-is-in/39872)

<div class="topic-metadata">

**Author:** [@Manoj\_Gopalkrishnan](https://discourse.julialang.org/u/Manoj_Gopalkrishnan)\
**Replies:** 2\
**Last updated:** [May 21, 2020, 9:42am UTC](https://discourse.julialang.org/t/having-trouble-figuring-out-which-line-the-error-is-in/39872 "2020-05-21T09:42:18Z")

</div>

When I get an error message like this: MethodError: Cannot \`convert\` an object of type Float64 to an object of type Array{Float64,1} Closest candidates are: convert(::Type{Array{Float64,1}}, !Matched::Sundials.NVector…

---

## [Generating Artifact.toml hashes](https://discourse.julialang.org/t/generating-artifact-toml-hashes/39685)

<div class="topic-metadata">

**Author:** [@torrance](https://discourse.julialang.org/u/torrance)\
**Replies:** 3\
**Last updated:** [May 21, 2020, 9:06am UTC](https://discourse.julialang.org/t/generating-artifact-toml-hashes/39685 "2020-05-21T09:06:10Z")

</div>

Hi there, I’m in the process of making my package relocatable, and the first steps for that are to create my shared libraries (actually, just library wrappers of C++ libraries) as artifacts. However, I’m finding the doc…

---

## [Using type system for different coordinate systems?](https://discourse.julialang.org/t/using-type-system-for-different-coordinate-systems/39722)

<div class="topic-metadata">

**Author:** [@benmatwil](https://discourse.julialang.org/u/benmatwil)\
**Replies:** 7\
**Last updated:** [May 21, 2020, 8:49am UTC](https://discourse.julialang.org/t/using-type-system-for-different-coordinate-systems/39722 "2020-05-21T08:49:57Z")

</div>

I’m reasonably new to using Julia but I’ve been trying to rewrite a Fortran package in Julia. It mainly runs in a Cartesian-like coordinate system with very small sections that require some specialisation for different c…

---

## [\[ANN\] View common generators as arrays](https://discourse.julialang.org/t/ann-view-common-generators-as-arrays/39707)

<div class="topic-metadata">

**Author:** [@klacru](https://discourse.julialang.org/u/klacru)\
**Replies:** 8\
**Last updated:** [May 21, 2020, 7:12am UTC](https://discourse.julialang.org/t/ann-view-common-generators-as-arrays/39707 "2020-05-21T07:12:32Z")

</div>

The new package GeneratorArrays effectively converts a generator into a lazy form of a read-only abstract array. The object array(f(i) for i in a) can be used like \[f(i) for i in a\] without using an extra array for stor…

---

## [I feel old, how the times have changed. Old document I written in 1991(Matrix inverse)](https://discourse.julialang.org/t/i-feel-old-how-the-times-have-changed-old-document-i-written-in-1991-matrix-inverse/39867)

<div class="topic-metadata">

**Author:** [@StevenSiew](https://discourse.julialang.org/u/StevenSiew)\
**Replies:** 1\
**Last updated:** [May 21, 2020, 3:54am UTC](https://discourse.julialang.org/t/i-feel-old-how-the-times-have-changed-old-document-i-written-in-1991-matrix-inverse/39867 "2020-05-21T03:54:45Z")

</div>

I feel old, how the times have changed. Old document I written in 1991(Matrix inverse). I was a student, I could not afford matlab, I thought I’ll be smart and write my own matrix code in C++ just for fun. julia\> a = ra…

---

## [Differential equations: Vern family solver, lazy option question](https://discourse.julialang.org/t/differential-equations-vern-family-solver-lazy-option-question/39865)

<div class="topic-metadata">

**Author:** [@Egwene\_al\_Vere](https://discourse.julialang.org/u/Egwene_al_Vere)\
**Replies:** 2\
**Last updated:** [May 21, 2020, 2:44am UTC](https://discourse.julialang.org/t/differential-equations-vern-family-solver-lazy-option-question/39865 "2020-05-21T02:44:43Z")

</div>

For the Verner family solver of DifferentialEquations.jl, Vern6() through Vern9(), it is documented that the interpolation is “lazy” and These methods when lazy assume that the parameter vector p will be unchanged be…

---

## [How to serialize and save variables (automatically)](https://discourse.julialang.org/t/how-to-serialize-and-save-variables-automatically/39849)

<div class="topic-metadata">

**Author:** [@volkerkarle](https://discourse.julialang.org/u/volkerkarle)\
**Replies:** 1\
**Last updated:** [May 21, 2020, 1:55am UTC](https://discourse.julialang.org/t/how-to-serialize-and-save-variables-automatically/39849 "2020-05-21T01:55:48Z")

</div>

Hi there, In my code I am using the JLD package to serialize my results. Up to now, I worked on an ad-hoc solution where this saving/ loading is done in the functions itself. Furthermore, I use dictionaries to save all …

---

## [Gurobi Lazyconstraints with JuMP 0.21](https://discourse.julialang.org/t/gurobi-lazyconstraints-with-jump-0-21/39863)

<div class="topic-metadata">

**Author:** [@Wei\_Wang](https://discourse.julialang.org/u/Wei_Wang)\
**Replies:** 2\
**Last updated:** [May 21, 2020, 1:40am UTC](https://discourse.julialang.org/t/gurobi-lazyconstraints-with-jump-0-21/39863 "2020-05-21T01:40:42Z")

</div>

Hi, I am transferring some codes from old package versions (Julia 0.64, JuMP 0.18, Gurobi 8.5) to current environment. But I got some problems with one using lazyconstraints. In the old environment, the problem was sol…

---

## [ModelingToolkit: using intermediate calculation results multiple times](https://discourse.julialang.org/t/modelingtoolkit-using-intermediate-calculation-results-multiple-times/39738)

<div class="topic-metadata">

**Author:** [@caryan](https://discourse.julialang.org/u/caryan)\
**Replies:** 7\
**Last updated:** [May 20, 2020, 10:42pm UTC](https://discourse.julialang.org/t/modelingtoolkit-using-intermediate-calculation-results-multiple-times/39738 "2020-05-20T22:42:03Z")

</div>

Let’s say I have an expensive scalar that shows up multiple times in my set of differential equations. Is there a way to tell ModelingToolkit to hoist that calculation out and only do it once? If I use an intermediate ca…

---

## [Juno: using a sysimage causes error](https://discourse.julialang.org/t/juno-using-a-sysimage-causes-error/27764)

<div class="topic-metadata">

**Author:** [@asprionj](https://discourse.julialang.org/u/asprionj)\
**Replies:** 4\
**Last updated:** [May 20, 2020, 10:41pm UTC](https://discourse.julialang.org/t/juno-using-a-sysimage-causes-error/27764 "2020-05-20T22:41:50Z")

</div>

I’m trying to use a custom system image for starting Julia in Juno. The system image was compiled by compile\_incremental or compile\_package from PackageCompiler, the result is the same. Now, when I try to start Julia in …

---

## [Is there a bug in large matrix inverse?](https://discourse.julialang.org/t/is-there-a-bug-in-large-matrix-inverse/39787)

<div class="topic-metadata">

**Author:** [@zxjroger](https://discourse.julialang.org/u/zxjroger)\
**Replies:** 6\
**Last updated:** [May 20, 2020, 10:33pm UTC](https://discourse.julialang.org/t/is-there-a-bug-in-large-matrix-inverse/39787 "2020-05-20T22:33:18Z")

</div>

I try to find the inverse of a symmetric matrix. For example, a = randn(100) b = a \* transpose(a) inv(b) \* b Here, matrix b is symmetric. However, inv(b) is not the correct inverse of matrix b. It is not symmetric and …

---

## [Constructor for SplitFunction SplitODEProblem](https://discourse.julialang.org/t/constructor-for-splitfunction-splitodeproblem/39854)

<div class="topic-metadata">

**Author:** [@mleprovost](https://discourse.julialang.org/u/mleprovost)\
**Replies:** 2\
**Last updated:** [May 20, 2020, 10:27pm UTC](https://discourse.julialang.org/t/constructor-for-splitfunction-splitodeproblem/39854 "2020-05-20T22:27:20Z")

</div>

Hello, I am looking for a constructor for SplitFunction for SplitODEProblem in DifferentialEquations.jl https://docs.sciml.ai/latest/types/split\_ode\_types/ Given f1 and f2, how do you define the corresponding SplitFun…

---

## [Using macros](https://discourse.julialang.org/t/using-macros/39656)

<div class="topic-metadata">

**Author:** [@Nimpa](https://discourse.julialang.org/u/Nimpa)\
**Replies:** 4\
**Last updated:** [May 20, 2020, 10:09pm UTC](https://discourse.julialang.org/t/using-macros/39656 "2020-05-20T22:09:21Z")

</div>

Hello, how can i write a macro that takes four argument , namely a Dict , a key ( of arbitaray type) , and two expressions such that if the Dict contains the key , its value is bound to the local variable it within the f…

---

## [MLJ: Evaluating a probabilistic metric and a deterministic metric at the same time](https://discourse.julialang.org/t/mlj-evaluating-a-probabilistic-metric-and-a-deterministic-metric-at-the-same-time/39775)

<div class="topic-metadata">

**Author:** [@CameronBieganek](https://discourse.julialang.org/u/CameronBieganek)\
**Replies:** 4\
**Last updated:** [May 20, 2020, 9:45pm UTC](https://discourse.julialang.org/t/mlj-evaluating-a-probabilistic-metric-and-a-deterministic-metric-at-the-same-time/39775 "2020-05-20T21:45:00Z")

</div>

The evaluate and evaluate! methods in MLJ can accept a vector of metric functions. However, it doesn’t appear that you can evaluate metrics based on probabilistic predictions (e.g. AUC) and metrics based on deterministic…

---

## ["vectorized" QuadGK?](https://discourse.julialang.org/t/vectorized-quadgk/39853)

<div class="topic-metadata">

**Author:** [@tbeason](https://discourse.julialang.org/u/tbeason)\
**Replies:** 3\
**Last updated:** [May 20, 2020, 9:17pm UTC](https://discourse.julialang.org/t/vectorized-quadgk/39853 "2020-05-20T21:17:46Z")

</div>

I’ll start off by saying that QuadGK is really fast. But I want to know how to make it faster for what I think is a relatively common usecase, which is its vectorized form. Broadcasting the quadgk call itself performs as…

---

## [Can't run jupyter notebook](https://discourse.julialang.org/t/cant-run-jupyter-notebook/39796)

<div class="topic-metadata">

**Author:** [@aebk2015](https://discourse.julialang.org/u/aebk2015)\
**Replies:** 12\
**Last updated:** [May 20, 2020, 7:30pm UTC](https://discourse.julialang.org/t/cant-run-jupyter-notebook/39796 "2020-05-20T19:30:13Z")

</div>

I can’t seem to start jupyter notebook from Mac terminal. I am using IJulia jupyterlab() or using IJulia jupyter notebook() When the browswer opnes and I select Julia for the kernel, I get this (I am pasting par…

---

## [Searchsorted by=\<transform\> keyword question](https://discourse.julialang.org/t/searchsorted-by-transform-keyword-question/39851)

<div class="topic-metadata">

**Author:** [@cstook](https://discourse.julialang.org/u/cstook)\
**Replies:** 2\
**Last updated:** [May 20, 2020, 7:10pm UTC](https://discourse.julialang.org/t/searchsorted-by-transform-keyword-question/39851 "2020-05-20T19:10:41Z")

</div>

I thought that the transform specified with the by keyword was a function applied before the comparison. I don’t understand the last three examples below. Probably missing something obvious. How does the by keyword wo…

---

## [Expected behaviour of println.(Array) (or @. println(Array) )](https://discourse.julialang.org/t/expected-behaviour-of-println-array-or-println-array/39846)

<div class="topic-metadata">

**Author:** [@CodeLenz](https://discourse.julialang.org/u/CodeLenz)\
**Replies:** 4\
**Last updated:** [May 20, 2020, 7:03pm UTC](https://discourse.julialang.org/t/expected-behaviour-of-println-array-or-println-array/39846 "2020-05-20T19:03:35Z")

</div>

Hi. Just to clarify a silly doubt. What is the expected behavior of println.(x) where x is an Array? I was expecting that println would be executed to each position of x, but julia\> x = rand(5) 5-element Array{Flo…

---

## [Julia equivalent of 'rm \*' (almost)](https://discourse.julialang.org/t/julia-equivalent-of-rm-almost/39477)

<div class="topic-metadata">

**Author:** [@compleat](https://discourse.julialang.org/u/compleat)\
**Replies:** 18\
**Last updated:** [May 20, 2020, 6:51pm UTC](https://discourse.julialang.org/t/julia-equivalent-of-rm-almost/39477 "2020-05-20T18:51:22Z")

</div>

Hello, let me begin by saying this is not a gripe, but rather a warning to users. I have lost lots of time on the following ‘fat finger’ error in Julia. Consider below. julia\> x=\[1;2;3\]; julia\> y=x\[x.==1\] 1-element …

---

## [PyPlot set facecolor](https://discourse.julialang.org/t/pyplot-set-facecolor/39794)

<div class="topic-metadata">

**Author:** [@qwerytyui1234](https://discourse.julialang.org/u/qwerytyui1234)\
**Replies:** 1\
**Last updated:** [May 20, 2020, 5:57pm UTC](https://discourse.julialang.org/t/pyplot-set-facecolor/39794 "2020-05-20T17:57:55Z")

</div>

Can anyone get this code to work? using Plots pyplot() fig, ax = PyPlot.subplots(facecolor=(0.5,0.2,0.5)) ax.plot(rand(10)) fig This code runs without any error message, but for some reason the background color for t…

---

## ["Partially" synchronizing asynchronous tasks](https://discourse.julialang.org/t/partially-synchronizing-asynchronous-tasks/39841)

<div class="topic-metadata">

**Author:** [@martincornejo](https://discourse.julialang.org/u/martincornejo)\
**Replies:** 2\
**Last updated:** [May 20, 2020, 5:29pm UTC](https://discourse.julialang.org/t/partially-synchronizing-asynchronous-tasks/39841 "2020-05-20T17:29:22Z")

</div>

The @sync / @async pair is very useful for waiting a series of asynchronous tasks to complete: @sync for element in collection @async perform\_task(element) end Is there a way to do something similar, but instead of …

---

## [Revise and include order in package under development](https://discourse.julialang.org/t/revise-and-include-order-in-package-under-development/39832)

<div class="topic-metadata">

**Author:** [@D\_A](https://discourse.julialang.org/u/D_A)\
**Replies:** 2\
**Last updated:** [May 20, 2020, 4:37pm UTC](https://discourse.julialang.org/t/revise-and-include-order-in-package-under-development/39832 "2020-05-20T16:37:00Z")

</div>

Hello, After I refactored my own set of code files into a package (with generate command), and using Revise prior to everything (thanks to the VS Code option), development got better, but I noticed some changes in my su…

---

## [\[ANN\] SimpleTranslations package](https://discourse.julialang.org/t/ann-simpletranslations-package/39842)

<div class="topic-metadata">

**Author:** [@dmolina](https://discourse.julialang.org/u/dmolina)\
**Replies:** 0\
**Last updated:** [May 20, 2020, 4:19pm UTC](https://discourse.julialang.org/t/ann-simpletranslations-package/39842 "2020-05-20T16:19:25Z")

</div>

SimpleTranslations is a simple way to translate the different messages to users (including the possible error messages) to different languages. This package raised as a need utility to translate several error messages …

---

## [Does adding dependencies increase compilation time?](https://discourse.julialang.org/t/does-adding-dependencies-increase-compilation-time/39766)

<div class="topic-metadata">

**Author:** [@BrucePBon](https://discourse.julialang.org/u/BrucePBon)\
**Replies:** 6\
**Last updated:** [May 20, 2020, 4:26pm UTC](https://discourse.julialang.org/t/does-adding-dependencies-increase-compilation-time/39766 "2020-05-20T16:26:37Z")

</div>

I am writing a Julia Package and I feel like compilation time of the package is longer than It was in the past. Does it have to do with the added dependencies? Should I only import those functions that my package uses? …

---

## [Strange MethodError ambiguity](https://discourse.julialang.org/t/strange-methoderror-ambiguity/39779)

<div class="topic-metadata">

**Author:** [@Bigorneau](https://discourse.julialang.org/u/Bigorneau)\
**Replies:** 6\
**Last updated:** [May 20, 2020, 3:46pm UTC](https://discourse.julialang.org/t/strange-methoderror-ambiguity/39779 "2020-05-20T15:46:25Z")

</div>

I found a strange MethodError in my code. It is possible to reproduce it with the following simple code struct A{T} x::T end fun(a::A{T}, b::T) where {T} = "same parametric type" fun(a::T, b::S) where {T\<:A,S} = "any…

---

## [Julian Way of Using Keyword Arguments](https://discourse.julialang.org/t/julian-way-of-using-keyword-arguments/39777)

<div class="topic-metadata">

**Author:** [@Ian\_Slagle](https://discourse.julialang.org/u/Ian_Slagle)\
**Replies:** 6\
**Last updated:** [May 20, 2020, 3:20pm UTC](https://discourse.julialang.org/t/julian-way-of-using-keyword-arguments/39777 "2020-05-20T15:20:29Z")

</div>

I am implementing a model for the units of a simple silica glass, and in doing so have come across some interesting questions on how to use keyword arguments. Essentially, there are two notations for how to represent the…

---

## [Using tables with gtk.jl and glade](https://discourse.julialang.org/t/using-tables-with-gtk-jl-and-glade/39840)

<div class="topic-metadata">

**Author:** [@Carlos\_Werner](https://discourse.julialang.org/u/Carlos_Werner)\
**Replies:** 0\
**Last updated:** [May 20, 2020, 3:08pm UTC](https://discourse.julialang.org/t/using-tables-with-gtk-jl-and-glade/39840 "2020-05-20T15:08:08Z")

</div>

I saw an example of creating tables with Gtk treeview, but i didn’t see anything with glade. Does anyone have an example to show?

---

## [Lorenz System VSSM controller](https://discourse.julialang.org/t/lorenz-system-vssm-controller/39817)

<div class="topic-metadata">

**Author:** [@TheBacha](https://discourse.julialang.org/u/TheBacha)\
**Replies:** 0\
**Last updated:** [May 20, 2020, 9:56am UTC](https://discourse.julialang.org/t/lorenz-system-vssm-controller/39817 "2020-05-20T09:56:27Z")

</div>

Hello guys I am working on a small project “VSSM controller” with Julia programming I only have two questions :slight\_smile: I have exact model parameters the function of time so it can be written in x(t), y(t), z(t)…

---

## [Delete!() row from DataFrame incompatible with CSV.jl?](https://discourse.julialang.org/t/delete-row-from-dataframe-incompatible-with-csv-jl/39835)

<div class="topic-metadata">

**Author:** [@Fred](https://discourse.julialang.org/u/Fred)\
**Replies:** 3\
**Last updated:** [May 20, 2020, 2:43pm UTC](https://discourse.julialang.org/t/delete-row-from-dataframe-incompatible-with-csv-jl/39835 "2020-05-20T14:43:59Z")

</div>

Hi ! Following some packages updates, the functions I add used to delete rows in dataframes, such as deleterows!(), have been deprecated and I try to make my old code running again but I face a difficult problem. When …

---

## [CPLEX.jl: how to call CPXcallbackgetinfoint?](https://discourse.julialang.org/t/cplex-jl-how-to-call-cpxcallbackgetinfoint/39834)

<div class="topic-metadata">

**Author:** [@mike\_k](https://discourse.julialang.org/u/mike_k)\
**Replies:** 1\
**Last updated:** [May 20, 2020, 2:36pm UTC](https://discourse.julialang.org/t/cplex-jl-how-to-call-cpxcallbackgetinfoint/39834 "2020-05-20T14:36:41Z")

</div>

Dear folks, I try to call CPXcallbackgetinfoint within a callback but unfortunately fail to do so. From what I could extract from the source code of the CPLEX package, it should work something like this: function myCal…

[Previous page](https://discourse.julialang.org/latest.md?page=1740)

[Next page](https://discourse.julialang.org/latest.md?page=1742)