# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1872

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

**Page:** 1873

---

## [Numerically stable computation of matrix power](https://discourse.julialang.org/t/numerically-stable-computation-of-matrix-power/31584)

<div class="topic-metadata">

**Author:** [@gmouts](https://discourse.julialang.org/u/gmouts)\
**Replies:** 14\
**Last updated:** [November 29, 2019, 4:51pm UTC](https://discourse.julialang.org/t/numerically-stable-computation-of-matrix-power/31584 "2019-11-29T16:51:20Z")

</div>

I admit the title is not great, but I couldn’t find a better one. I have a matrix M whose eigenvalues lie in the unit disk and the only eigenvalue on the unit cycle is 1. Moreover the algebraic multiplicity of the eigen…

---

## [(Efficient) function to create a Histogram incrementally without plotting it?](https://discourse.julialang.org/t/efficient-function-to-create-a-histogram-incrementally-without-plotting-it/31651)

<div class="topic-metadata">

**Author:** [@Massimiliano\_Comin](https://discourse.julialang.org/u/Massimiliano_Comin)\
**Replies:** 2\
**Last updated:** [November 29, 2019, 4:26pm UTC](https://discourse.julialang.org/t/efficient-function-to-create-a-histogram-incrementally-without-plotting-it/31651 "2019-11-29T16:26:42Z")

</div>

Hello, I have many random vectors (all of the same nature/size of course) that I want to bin inside a fixed histogram. So basically I would like to incrementally fill a histogram without plotting it, in an efficient fas…

---

## [\[ANN\] PPN.jl and Gomah.jl](https://discourse.julialang.org/t/ann-ppn-jl-and-gomah-jl/31665)

<div class="topic-metadata">

**Author:** [@terasakisatoshi](https://discourse.julialang.org/u/terasakisatoshi)\
**Replies:** 0\
**Last updated:** [November 29, 2019, 4:09pm UTC](https://discourse.julialang.org/t/ann-ppn-jl-and-gomah-jl/31665 "2019-11-29T16:09:00Z")

</div>

I’m happy to announce the release of PPN.jl which is a Deep Learning based Pose Estimation application that utilizes Chainer and Flux.jl. It includes demo script that captures image from camera (via VideoIO.jl, Images.…

---

## [Leave first type unspecified](https://discourse.julialang.org/t/leave-first-type-unspecified/31661)

<div class="topic-metadata">

**Author:** [@matthieu](https://discourse.julialang.org/u/matthieu)\
**Replies:** 1\
**Last updated:** [November 29, 2019, 3:58pm UTC](https://discourse.julialang.org/t/leave-first-type-unspecified/31661 "2019-11-29T15:58:55Z")

</div>

Suppose I have a type with multiple parameters and that I want to define a function that dispatch only on the second parameter. Is there a way to leave the first parameter unspecified? As an example, I would like to def…

---

## [Is operating a vector that have abstract type really slow?](https://discourse.julialang.org/t/is-operating-a-vector-that-have-abstract-type-really-slow/31634)

<div class="topic-metadata">

**Author:** [@ke\_xu](https://discourse.julialang.org/u/ke_xu)\
**Replies:** 11\
**Last updated:** [November 29, 2019, 3:18pm UTC](https://discourse.julialang.org/t/is-operating-a-vector-that-have-abstract-type-really-slow/31634 "2019-11-29T15:18:10Z")

</div>

using BenchmarkTools abstract type SuperType end mutable struct TypeA \<: SuperType a::Int64 b::Int64 end mutable struct TypeB \<: SuperType a::Int64 b::Float64 end function Iter(objs::Vector{SuperType}) …

---

## [Weird behaviour on contour plot update](https://discourse.julialang.org/t/weird-behaviour-on-contour-plot-update/31572)

<div class="topic-metadata">

**Author:** [@Andre\_Mello](https://discourse.julialang.org/u/Andre_Mello)\
**Replies:** 10\
**Last updated:** [November 29, 2019, 2:45pm UTC](https://discourse.julialang.org/t/weird-behaviour-on-contour-plot-update/31572 "2019-11-29T14:45:05Z")

</div>

It seems like if the differences in the contour levels are too small, updating the plot breaks its colors. Here’s a MWE to make things clearer. using Plots x = -0.1:0.01:0.1 y = -0.1:0.01:0.1 z = \[i^2+j^2 for i in x, …

---

## [Emacs with Julia on Windows](https://discourse.julialang.org/t/emacs-with-julia-on-windows/31612)

<div class="topic-metadata">

**Author:** [@PetrKryslUCSD](https://discourse.julialang.org/u/PetrKryslUCSD)\
**Replies:** 19\
**Last updated:** [November 29, 2019, 12:49pm UTC](https://discourse.julialang.org/t/emacs-with-julia-on-windows/31612 "2019-11-29T12:49:36Z")

</div>

Emacs running under Cygwin is perfectly usable and very functional when programming in Julia. It has been tested under Windows 10. Evaluation of code in files, interactive REPL, git, tags, multiple cursors, snippets, ab…

---

## [Interval arithmetic - computation time](https://discourse.julialang.org/t/interval-arithmetic-computation-time/14633)

<div class="topic-metadata">

**Author:** [@OlivierHnt](https://discourse.julialang.org/u/OlivierHnt)\
**Replies:** 16\
**Last updated:** [November 29, 2019, 10:02am UTC](https://discourse.julialang.org/t/interval-arithmetic-computation-time/14633 "2019-11-29T10:02:37Z")

</div>

Hi, I just started using the IntervalArithmetic package for Julia. For the same computations, Matlab (using IntLab) performs extremely well in comparison with Julia. The implementation has ben adapted, that is the compu…

---

## [Update existing plot instead of showing a new one](https://discourse.julialang.org/t/update-existing-plot-instead-of-showing-a-new-one/31630)

<div class="topic-metadata">

**Author:** [@maximilianpreisinger](https://discourse.julialang.org/u/maximilianpreisinger)\
**Replies:** 1\
**Last updated:** [November 29, 2019, 9:53am UTC](https://discourse.julialang.org/t/update-existing-plot-instead-of-showing-a-new-one/31630 "2019-11-29T09:53:12Z")

</div>

Hi guys, the whole plotting stuff very confuses me. For example I manage to display my plot with Plots.jl with the plotlyjs backend (it opens a new browser tab and shows my plot), and I am happy with it. However I do no…

---

## [\[update\] DoubleFloats](https://discourse.julialang.org/t/update-doublefloats/24203)

<div class="topic-metadata">

**Author:** [@JeffreySarnoff](https://discourse.julialang.org/u/JeffreySarnoff)\
**Replies:** 1\
**Last updated:** [November 29, 2019, 9:49am UTC](https://discourse.julialang.org/t/update-doublefloats/24203 "2019-11-29T09:49:46Z")

</div>

Thanks to the interest of others, DoubleFloats turns v0.8 today. There is another package, Quadmath.jl, which exports Float128 from GNU’s libquadmath. Float128s have 6 more significant bits than Double64s, and a much …

---

## [Pmap and multi-threaded BLAS](https://discourse.julialang.org/t/pmap-and-multi-threaded-blas/31617)

<div class="topic-metadata">

**Author:** [@ahthomas](https://discourse.julialang.org/u/ahthomas)\
**Replies:** 2\
**Last updated:** [November 29, 2019, 9:29am UTC](https://discourse.julialang.org/t/pmap-and-multi-threaded-blas/31617 "2019-11-29T09:29:10Z")

</div>

When I run a call to one of the low level LinearAlgebra.BLAS functions inside a function executed on a worker process launched via pmap it appears that BLAS does not use multiple threads. Here is a simple example: using…

---

## [How to get the current “random” seed?](https://discourse.julialang.org/t/how-to-get-the-current-random-seed/31640)

<div class="topic-metadata">

**Author:** [@monty](https://discourse.julialang.org/u/monty)\
**Replies:** 2\
**Last updated:** [November 29, 2019, 6:44am UTC](https://discourse.julialang.org/t/how-to-get-the-current-random-seed/31640 "2019-11-29T06:44:56Z")

</div>

How to get the current “random” seed? Random.GLOBAL\_RNG.seed is not available now.

---

## [ARPA-E DIFFERENTIATE program](https://discourse.julialang.org/t/arpa-e-differentiate-program/31316)

<div class="topic-metadata">

**Author:** [@monty](https://discourse.julialang.org/u/monty)\
**Replies:** 14\
**Last updated:** [November 29, 2019, 6:36am UTC](https://discourse.julialang.org/t/arpa-e-differentiate-program/31316 "2019-11-29T06:36:41Z")

</div>

Julia is a big winner in the ARPA E dIFFERENTIATE program. ARPA-E just announced that will fund 23 Projects to Accelerate the Energy Technology Design Process. Three of the projects will use Julia to build computational…

---

## [Rewriting function on CPU for execution on GPU](https://discourse.julialang.org/t/rewriting-function-on-cpu-for-execution-on-gpu/31608)

<div class="topic-metadata">

**Author:** [@ennvvy](https://discourse.julialang.org/u/ennvvy)\
**Replies:** 4\
**Last updated:** [November 29, 2019, 5:48am UTC](https://discourse.julialang.org/t/rewriting-function-on-cpu-for-execution-on-gpu/31608 "2019-11-29T05:48:00Z")

</div>

I am trying to execute a function that I am currently running on a CPU on the GPU. There are a few bottlenecks, like accessing elements of an array scalar getindex is disallowed The code is below: using CUDAdrv,CUDAnat…

---

## [How to make this piece of code faster? optimising it or using multiple threads?](https://discourse.julialang.org/t/how-to-make-this-piece-of-code-faster-optimising-it-or-using-multiple-threads/30590)

<div class="topic-metadata">

**Author:** [@ennvvy](https://discourse.julialang.org/u/ennvvy)\
**Replies:** 68\
**Last updated:** [November 29, 2019, 5:39am UTC](https://discourse.julialang.org/t/how-to-make-this-piece-of-code-faster-optimising-it-or-using-multiple-threads/30590 "2019-11-29T05:39:35Z")

</div>

I have a piece of code involving a large matrix. I have been trying to optimise it. I have exhausted all my options, I would like to know of suggestions that experts on this forum might have. using Distributions using S…

---

## [Why mul! is so fast with BitVector?](https://discourse.julialang.org/t/why-mul-is-so-fast-with-bitvector/31629)

<div class="topic-metadata">

**Author:** [@e3c6](https://discourse.julialang.org/u/e3c6)\
**Replies:** 1\
**Last updated:** [November 29, 2019, 12:45am UTC](https://discourse.julialang.org/t/why-mul-is-so-fast-with-bitvector/31629 "2019-11-29T00:45:49Z")

</div>

Consider the following example code: using LinearAlgebra, BenchmarkTools n = 200 xb = BitVector(rand(Bool, n)) xf = Float32.(xb) W = randn(Float32,n,n) y = zeros(Float32,n); function mymul!(y, A, x) y .= 0 @in…

---

## [New Julia user seeking feedback on an in-progress project](https://discourse.julialang.org/t/new-julia-user-seeking-feedback-on-an-in-progress-project/31410)

<div class="topic-metadata">

**Author:** [@otde](https://discourse.julialang.org/u/otde)\
**Replies:** 5\
**Last updated:** [November 28, 2019, 8:16pm UTC](https://discourse.julialang.org/t/new-julia-user-seeking-feedback-on-an-in-progress-project/31410 "2019-11-28T20:16:03Z")

</div>

https://github.com/OTDE/RenderingGeometry.jl Hi folks! I’m a new Julia user transitioning from Java. Thanks to the folks in the #helpdesk channel on the Slack, I’ve been learning a lot. I’ve started work on a port of th…

---

## [Why Tab in session requires pressing more than once](https://discourse.julialang.org/t/why-tab-in-session-requires-pressing-more-than-once/31546)

<div class="topic-metadata">

**Author:** [@Usor](https://discourse.julialang.org/u/Usor)\
**Replies:** 5\
**Last updated:** [November 28, 2019, 7:45pm UTC](https://discourse.julialang.org/t/why-tab-in-session-requires-pressing-more-than-once/31546 "2019-11-28T19:45:22Z")

</div>

If using Tab to complete or suggest something, often it is required to do so more than once. Why? How can it be fixed?

---

## [Most efficient way: create/mutate DataFrame time column](https://discourse.julialang.org/t/most-efficient-way-create-mutate-dataframe-time-column/31548)

<div class="topic-metadata">

**Author:** [@Usor](https://discourse.julialang.org/u/Usor)\
**Replies:** 8\
**Last updated:** [November 28, 2019, 6:46pm UTC](https://discourse.julialang.org/t/most-efficient-way-create-mutate-dataframe-time-column/31548 "2019-11-28T18:46:02Z")

</div>

Suppose you have a DataFrame, which has a column called Year (with Int64). Then it has a column called Month (with String). Yes, suppose you have 12 rows with the integer year 2000 and the 12 months January to December a…

---

## [\[ANN\] LengthChannels - Buffered iterators for machine learning](https://discourse.julialang.org/t/ann-lengthchannels-buffered-iterators-for-machine-learning/31566)

<div class="topic-metadata">

**Author:** [@baggepinnen](https://discourse.julialang.org/u/baggepinnen)\
**Replies:** 2\
**Last updated:** [November 28, 2019, 4:42pm UTC](https://discourse.julialang.org/t/ann-lengthchannels-buffered-iterators-for-machine-learning/31566 "2019-11-28T16:42:11Z")

</div>

There has recently been many threads talking about buffered data loaders for machine learning workflows, e.g. https://discourse.julialang.org/t/pytorch-dataloader-equivalent-for-training-large-models-with-flux/. I have …

---

## [PARTR support for BLAS](https://discourse.julialang.org/t/partr-support-for-blas/31581)

<div class="topic-metadata">

**Author:** [@Yifan\_Liu](https://discourse.julialang.org/u/Yifan_Liu)\
**Replies:** 3\
**Last updated:** [November 28, 2019, 4:07pm UTC](https://discourse.julialang.org/t/partr-support-for-blas/31581 "2019-11-28T16:07:19Z")

</div>

I noticed that Julia 1.4 will have partr thread support for openblas. just curious, what kind of tasks will benefit from this support.

---

## [Callbacks on parts of SharedArrays](https://discourse.julialang.org/t/callbacks-on-parts-of-sharedarrays/31624)

<div class="topic-metadata">

**Author:** [@hcarlsso](https://discourse.julialang.org/u/hcarlsso)\
**Replies:** 0\
**Last updated:** [November 28, 2019, 1:50pm UTC](https://discourse.julialang.org/t/callbacks-on-parts-of-sharedarrays/31624 "2019-11-28T13:50:39Z")

</div>

The problem I have is how to define functions that modify parts of SharedArrays. What I want to achieve is the following: using Distributed addprocs(2) @everywhere using SharedArrays @everywhere function temp(trace) …

---

## [Writing simple kernel functions (EM algorithm)](https://discourse.julialang.org/t/writing-simple-kernel-functions-em-algorithm/24787)

<div class="topic-metadata">

**Author:** [@myroslav](https://discourse.julialang.org/u/myroslav)\
**Replies:** 7\
**Last updated:** [November 28, 2019, 2:39pm UTC](https://discourse.julialang.org/t/writing-simple-kernel-functions-em-algorithm/24787 "2019-11-28T14:39:12Z")

</div>

Hi everyone, I am trying to get my head around writing GPU kernels in Julia, would be great if someone could help me with my example. Without going into too many details, I am trying to run a simple EM (Expectation-Maxi…

---

## [Whom to follow on GitHub?](https://discourse.julialang.org/t/whom-to-follow-on-github/31623)

<div class="topic-metadata">

**Author:** [@ven-k](https://discourse.julialang.org/u/ven-k)\
**Replies:** 1\
**Last updated:** [November 28, 2019, 1:55pm UTC](https://discourse.julialang.org/t/whom-to-follow-on-github/31623 "2019-11-28T13:55:27Z")

</div>

I want to contribute to open source; specifically in machine learning domain with Julia. I want to know who all to follow on GitHub to get to know the community, new trends etc.

---

## [How to activate anaconda3\\Scripts\\activate.bat in Atom Juno](https://discourse.julialang.org/t/how-to-activate-anaconda3-scripts-activate-bat-in-atom-juno/31618)

<div class="topic-metadata">

**Author:** [@Sijun](https://discourse.julialang.org/u/Sijun)\
**Replies:** 1\
**Last updated:** [November 28, 2019, 11:59am UTC](https://discourse.julialang.org/t/how-to-activate-anaconda3-scripts-activate-bat-in-atom-juno/31618 "2019-11-28T11:59:53Z")

</div>

Hello, I just discovered that pyimport failed if conda environment is not activated with anaconda3\\Scripts\\activate.bat. How can I activate it from within atom Juno? Thank you!

---

## [How to check if a package is installed (in the LOAD\_PATH)?](https://discourse.julialang.org/t/how-to-check-if-a-package-is-installed-in-the-load-path/31610)

<div class="topic-metadata">

**Author:** [@carstenbauer](https://discourse.julialang.org/u/carstenbauer)\
**Replies:** 10\
**Last updated:** [November 28, 2019, 10:10am UTC](https://discourse.julialang.org/t/how-to-check-if-a-package-is-installed-in-the-load-path/31610 "2019-11-28T10:10:12Z")

</div>

There has been a similar discussion in New Pkg: how to check if a package is installed? but the OP was satisfied with a solution based on Pkg.installed(). This, however, only checks whether MyPackage is installed in the …

---

## [PGFPlotsX: Hexagonal binning](https://discourse.julialang.org/t/pgfplotsx-hexagonal-binning/31580)

<div class="topic-metadata">

**Author:** [@fipelle](https://discourse.julialang.org/u/fipelle)\
**Replies:** 2\
**Last updated:** [November 28, 2019, 7:04am UTC](https://discourse.julialang.org/t/pgfplotsx-hexagonal-binning/31580 "2019-11-28T07:04:14Z")

</div>

Do you know of any gallery for PGFPlots that include an exagonal binning chart similar to Has anyone made scatter plots with hexagonal binning?? An example / gallery in LaTeX would also work.

---

## [Transformations on a 2D view's indices?](https://discourse.julialang.org/t/transformations-on-a-2d-views-indices/31609)

<div class="topic-metadata">

**Author:** [@ianshmean](https://discourse.julialang.org/u/ianshmean)\
**Replies:** 0\
**Last updated:** [November 28, 2019, 6:38am UTC](https://discourse.julialang.org/t/transformations-on-a-2d-views-indices/31609 "2019-11-28T06:38:25Z")

</div>

Is there a way to take a view on a 2D matrix, and do things like translate the indices, or even rotate the view? Say, something like this. using ColorTypes, ImageView x = zeros(RGBA, 1000, 1000) v = view(x, 400:600, 400…

---

## [Performance of kernel function](https://discourse.julialang.org/t/performance-of-kernel-function/31605)

<div class="topic-metadata">

**Author:** [@ennvvy](https://discourse.julialang.org/u/ennvvy)\
**Replies:** 3\
**Last updated:** [November 28, 2019, 5:35am UTC](https://discourse.julialang.org/t/performance-of-kernel-function/31605 "2019-11-28T05:35:11Z")

</div>

I tried executing the following function on the GPU, for array sizes of 10,000. function update!(s,c,cedg,θ) index = (blockIdx().x - 1) \* blockDim().x + threadIdx().x stride = blockDim().x \* gridDim().x @inbounds …

---

## [Convert array of tuples to vector](https://discourse.julialang.org/t/convert-array-of-tuples-to-vector/31603)

<div class="topic-metadata">

**Author:** [@sboysel](https://discourse.julialang.org/u/sboysel)\
**Replies:** 6\
**Last updated:** [November 28, 2019, 3:49am UTC](https://discourse.julialang.org/t/convert-array-of-tuples-to-vector/31603 "2019-11-28T03:49:28Z")

</div>

I have an array of homogenous tuples (all the same length with elements of the same type). I’d like collapse or unpack this array into a single vector containing all elements of the tuples. Order does not matter in my …

[Previous page](https://discourse.julialang.org/latest.md?page=1871)

[Next page](https://discourse.julialang.org/latest.md?page=1873)