# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1380

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

**Page:** 1381

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## [Specifying the numerical precision and ranks of the array arguments of a function](https://discourse.julialang.org/t/specifying-the-numerical-precision-and-ranks-of-the-array-arguments-of-a-function/61814)

<div class="topic-metadata">

**Author:** [@Beliavsky](https://discourse.julialang.org/u/Beliavsky)\
**Replies:** 3\
**Last updated:** [May 25, 2021, 9:20pm UTC](https://discourse.julialang.org/t/specifying-the-numerical-precision-and-ranks-of-the-array-arguments-of-a-function/61814 "2021-05-25T21:20:53Z")

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Following is a Fortran function for matrix vector multiplication. It specifies that a(:,:) is a rank-2 array of 64-bit floats and that x(:) and b(:) are rank-1 arrays of 64-bit floats. function matrix\_vec\_mult(a,x) resu…

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## [I don't understand this bug](https://discourse.julialang.org/t/i-dont-understand-this-bug/61789)

<div class="topic-metadata">

**Author:** [@Scarlov](https://discourse.julialang.org/u/Scarlov)\
**Replies:** 12\
**Last updated:** [May 25, 2021, 8:00pm UTC](https://discourse.julialang.org/t/i-dont-understand-this-bug/61789 "2021-05-25T20:00:50Z")

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When I run this code: using Printf function choose\_best\_sum(t, k, ls) ran = range(1, length(ls), step = 1) choices = unique!(\[sort(\[ls\[i\], ls\[j\], ls\[m\]\]) for i in ran for j in ran for m in ran if( i != j && j !…

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## [COSMO.jl & Convex.jl: setting intial values](https://discourse.julialang.org/t/cosmo-jl-convex-jl-setting-intial-values/61381)

<div class="topic-metadata">

**Author:** [@lrnv](https://discourse.julialang.org/u/lrnv)\
**Replies:** 4\
**Last updated:** [May 25, 2021, 7:49pm UTC](https://discourse.julialang.org/t/cosmo-jl-convex-jl-setting-intial-values/61381 "2021-05-25T19:49:44Z")

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Hi, I’m using COSMO.jl as a solver from Convex.jl. I’m solving tseveral ‘related problems’ over and over again, which correspond to more precise versions of each others. I’d like to use the COSMO.jl warm starting featu…

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## [Contiguous setindex involving an adjoint is slower than non-contiguous for a Matrix](https://discourse.julialang.org/t/contiguous-setindex-involving-an-adjoint-is-slower-than-non-contiguous-for-a-matrix/61767)

<div class="topic-metadata">

**Author:** [@jishnub](https://discourse.julialang.org/u/jishnub)\
**Replies:** 5\
**Last updated:** [May 25, 2021, 7:37pm UTC](https://discourse.julialang.org/t/contiguous-setindex-involving-an-adjoint-is-slower-than-non-contiguous-for-a-matrix/61767 "2021-05-25T19:37:28Z")

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julia\> a = zeros(500,500); julia\> b = zeros(500,500)'; julia\> v = 1:500; julia\> @btime $a\[1,:\] = $v; 711.515 ns (0 allocations: 0 bytes) julia\> @btime $b\[1,:\] = $v; 808.444 ns (0 allocations: 0 bytes) julia\> @bt…

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## [Julia Computing: Cloud Engineer](https://discourse.julialang.org/t/julia-computing-cloud-engineer/61807)

<div class="topic-metadata">

**Author:** [@avik](https://discourse.julialang.org/u/avik)\
**Replies:** 0\
**Last updated:** [May 25, 2021, 7:08pm UTC](https://discourse.julialang.org/t/julia-computing-cloud-engineer/61807 "2021-05-25T19:08:29Z")

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Hi Folks, As we scale up our products on the cloud at Julia Computing, we wish to hire a Cloud Engineer with expertise on Amazon Web Services to be part of our product development team. Job duties and responsibilities …

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## [U. Michigan Online Course Computational ML for Scientists and Engineers](https://discourse.julialang.org/t/u-michigan-online-course-computational-ml-for-scientists-and-engineers/52574)

<div class="topic-metadata">

**Author:** [@rajnrao](https://discourse.julialang.org/u/rajnrao)\
**Replies:** 5\
**Last updated:** [May 25, 2021, 7:01pm UTC](https://discourse.julialang.org/t/u-michigan-online-course-computational-ml-for-scientists-and-engineers/52574 "2021-05-25T19:01:19Z")

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The University of Michigan’s Continuum Jumpstart Course Computational Machine Learning (ML) for Scientists and Engineers is designed to equip you with the knowledge you need to understand, train, design and machine learn…

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## [JuliaDB ignoring variables of the wrong type](https://discourse.julialang.org/t/juliadb-ignoring-variables-of-the-wrong-type/61739)

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**Author:** [@Joao](https://discourse.julialang.org/u/Joao)\
**Replies:** 3\
**Last updated:** [May 25, 2021, 5:58pm UTC](https://discourse.julialang.org/t/juliadb-ignoring-variables-of-the-wrong-type/61739 "2021-05-25T17:58:36Z")

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Hello all. First days in Julia, so please be patient. :slight\_smile: I am reading a table with JuliaDB and one of the variables is an integer. I have declared that with colparsers. Julia gives an error if the variable i…

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## [Macro defining an internal macro?](https://discourse.julialang.org/t/macro-defining-an-internal-macro/61700)

<div class="topic-metadata">

**Author:** [@Mark\_Nahabedian](https://discourse.julialang.org/u/Mark_Nahabedian)\
**Replies:** 10\
**Last updated:** [May 25, 2021, 5:41pm UTC](https://discourse.julialang.org/t/macro-defining-an-internal-macro/61700 "2021-05-25T17:41:45Z")

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I need some help with macros. I have a directed graph that is represented by a collection of Pairs where each Pair represents an arc of the graph. I want to perform some transformations on the graph. Each transformati…

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## [Loading another package when loading a package](https://discourse.julialang.org/t/loading-another-package-when-loading-a-package/61795)

<div class="topic-metadata">

**Author:** [@gitboy16](https://discourse.julialang.org/u/gitboy16)\
**Replies:** 1\
**Last updated:** [May 25, 2021, 5:03pm UTC](https://discourse.julialang.org/t/loading-another-package-when-loading-a-package/61795 "2021-05-25T17:03:36Z")

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Hi, Is there a way to load packageA when I load packageB? Example, if I do using packageB Then packageA is also available. Thank you

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## [Code fails in jupyter notebook, but succeeds in REPL](https://discourse.julialang.org/t/code-fails-in-jupyter-notebook-but-succeeds-in-repl/61793)

<div class="topic-metadata">

**Author:** [@PeterVincent96](https://discourse.julialang.org/u/PeterVincent96)\
**Replies:** 0\
**Last updated:** [May 25, 2021, 4:40pm UTC](https://discourse.julialang.org/t/code-fails-in-jupyter-notebook-but-succeeds-in-repl/61793 "2021-05-25T16:40:31Z")

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I have the following code using Statistics using LinearAlgebra using ForwardDiff using Plots plotlyjs() ENV\["JULIA\_REVISE\_POLL"\] = "1" using Revise using Distributions using DelimitedFiles include("path/to/files.jl") d…

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## [Weird behavior: \`UndefVarError:\` module function needs to be called with ModuleName.function](https://discourse.julialang.org/t/weird-behavior-undefvarerror-module-function-needs-to-be-called-with-modulename-function/61790)

<div class="topic-metadata">

**Author:** [@cdawg](https://discourse.julialang.org/u/cdawg)\
**Replies:** 2\
**Last updated:** [May 25, 2021, 4:34pm UTC](https://discourse.julialang.org/t/weird-behavior-undefvarerror-module-function-needs-to-be-called-with-modulename-function/61790 "2021-05-25T16:34:31Z")

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This has come up a couple times for me but I’m daunted by the idea of getting an MRE because it is rare. I write a non-exported helper function or method extension inside a module and it is undefined unless I call it wi…

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## [Troubles with SimJulia Doc](https://discourse.julialang.org/t/troubles-with-simjulia-doc/41855)

<div class="topic-metadata">

**Author:** [@ameresv](https://discourse.julialang.org/u/ameresv)\
**Replies:** 4\
**Last updated:** [May 25, 2021, 3:40pm UTC](https://discourse.julialang.org/t/troubles-with-simjulia-doc/41855 "2021-05-25T15:40:04Z")

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Hi! I am reading the SimJulia documentation in order to know more about the capabilities of the package. However, when I run it, an error message appears: using SimJulia function car(env::Environment) while true …

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## [Do you have a clean way of looping through an array?](https://discourse.julialang.org/t/do-you-have-a-clean-way-of-looping-through-an-array/61788)

<div class="topic-metadata">

**Author:** [@PetrKryslUCSD](https://discourse.julialang.org/u/PetrKryslUCSD)\
**Replies:** 6\
**Last updated:** [May 25, 2021, 3:38pm UTC](https://discourse.julialang.org/t/do-you-have-a-clean-way-of-looping-through-an-array/61788 "2021-05-25T15:38:25Z")

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Post it here. And when I say clean, it doesn’t mean clever. (I usually find that the clever ways of doing things are not the most legible.)

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## [Performance of \`Union{Missing,Float64}\`](https://discourse.julialang.org/t/performance-of-union-missing-float64/16348)

<div class="topic-metadata">

**Author:** [@e3c6](https://discourse.julialang.org/u/e3c6)\
**Replies:** 14\
**Last updated:** [May 25, 2021, 2:47pm UTC](https://discourse.julialang.org/t/performance-of-union-missing-float64/16348 "2021-05-25T14:47:04Z")

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From https://julialang.org/blog/2018/06/missing: For example, missing values still have a significant performance impact for arrays of Float64 elements, which are essential for numeric computing. function sum\_nonmis…

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## [Specifying index without access to array](https://discourse.julialang.org/t/specifying-index-without-access-to-array/61693)

<div class="topic-metadata">

**Author:** [@jzr](https://discourse.julialang.org/u/jzr)\
**Replies:** 9\
**Last updated:** [May 25, 2021, 2:35pm UTC](https://discourse.julialang.org/t/specifying-index-without-access-to-array/61693 "2021-05-25T14:35:31Z")

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In Python, I can get the the second-to-last value of an array using a nice syntax: \>\>\> ix = -2 \>\>\> lst = \[10, 20, 30, 40\] \>\>\> lst\[ix\] 30 but I can’t do this in Julia: julia\> lst = \[10, 20, 30, 40\]; julia\> ix = end - 2…

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## [Update vector without using a counter in a multithreaded loop](https://discourse.julialang.org/t/update-vector-without-using-a-counter-in-a-multithreaded-loop/61776)

<div class="topic-metadata">

**Author:** [@Iulian.Cioarca](https://discourse.julialang.org/u/Iulian.Cioarca)\
**Replies:** 4\
**Last updated:** [May 25, 2021, 2:28pm UTC](https://discourse.julialang.org/t/update-vector-without-using-a-counter-in-a-multithreaded-loop/61776 "2021-05-25T14:28:24Z")

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I would like to convert the following simplified example: n=10 x = Vector{Float64}(undef,n) y = 1:10 Threads.@threads for i=1:length(y) x\[i\] = y\[i\] \* 2.0 end into: n=10 x = Vector{Float64}(undef,n) y = 1:10 Thread…

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## [A subtle bug?](https://discourse.julialang.org/t/a-subtle-bug/61725)

<div class="topic-metadata">

**Author:** [@tomtom](https://discourse.julialang.org/u/tomtom)\
**Replies:** 21\
**Last updated:** [May 25, 2021, 1:45pm UTC](https://discourse.julialang.org/t/a-subtle-bug/61725 "2021-05-25T13:45:59Z")

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I got a Float64 number from the p-value of a GLM model. I could NOT show the fitted model with the following error: ERROR: p-values must be in \[0; 1\] Stacktrace: \[1\] error(::String) at ./error.jl:33 \[2\] StatsBase.PVa…

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## [Threads.@threads parallelism and htop](https://discourse.julialang.org/t/threads-threads-parallelism-and-htop/61762)

<div class="topic-metadata">

**Author:** [@cricci](https://discourse.julialang.org/u/cricci)\
**Replies:** 2\
**Last updated:** [May 25, 2021, 1:45pm UTC](https://discourse.julialang.org/t/threads-threads-parallelism-and-htop/61762 "2021-05-25T13:45:03Z")

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Hello, on my machine I am observing the following behavior when running julia 1.6 and using DifferentialEquations.jl to solve a PDE. Basically I wrote a function f!(du,u,p,t) that uses the macro Threads.@threads insid…

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## [Reusing temporary variables (ed: Object Pools)](https://discourse.julialang.org/t/reusing-temporary-variables-ed-object-pools/61726)

<div class="topic-metadata">

**Author:** [@cortner](https://discourse.julialang.org/u/cortner)\
**Replies:** 16\
**Last updated:** [May 25, 2021, 1:18pm UTC](https://discourse.julialang.org/t/reusing-temporary-variables-ed-object-pools/61726 "2021-05-25T13:18:56Z")

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In most of my producton codes I am very cautious about making performance critical parts non-allocating and passing in temporary variables (e.g. large arrays, NamedTuples of arrays, etc). This results in code of the form …

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## [Programmatic access to REPL like Pkg, Debugger, etc](https://discourse.julialang.org/t/programmatic-access-to-repl-like-pkg-debugger-etc/61723)

<div class="topic-metadata">

**Author:** [@minshall](https://discourse.julialang.org/u/minshall)\
**Replies:** 3\
**Last updated:** [May 25, 2021, 12:41pm UTC](https://discourse.julialang.org/t/programmatic-access-to-repl-like-pkg-debugger-etc/61723 "2021-05-25T12:41:21Z")

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hi. i’d like to interact with the user of my julia program with the input being more “command line” than “function call” like, but take advantage of the command line editing, history, etc., the REPL offers. so, the use…

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## [Trying to CVODE\_BDF with complex-valued ODE (?)](https://discourse.julialang.org/t/trying-to-cvode-bdf-with-complex-valued-ode/61710)

<div class="topic-metadata">

**Author:** [@Caique\_Rodrigues](https://discourse.julialang.org/u/Caique_Rodrigues)\
**Replies:** 8\
**Last updated:** [May 25, 2021, 11:54am UTC](https://discourse.julialang.org/t/trying-to-cvode-bdf-with-complex-valued-ode/61710 "2021-05-25T11:54:47Z")

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Most of the systems that I solve have complex-valued functions and, until now, I always separate the real and imaginary part of each equation to solve them in the real domain, i.e., going from a single complex equation t…

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## [How do I populate select dropdown from an array of strings?](https://discourse.julialang.org/t/how-do-i-populate-select-dropdown-from-an-array-of-strings/61757)

<div class="topic-metadata">

**Author:** [@scotts](https://discourse.julialang.org/u/scotts)\
**Replies:** 2\
**Last updated:** [May 25, 2021, 11:51am UTC](https://discourse.julialang.org/t/how-do-i-populate-select-dropdown-from-an-array-of-strings/61757 "2021-05-25T11:51:42Z")

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I have an array of strings that I want to use to populate an input select dropdown element in Pluto. Without any detailed documentation I’ve been really struggling. So far, I have found only one way to create the dropdo…

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## [I still can't use Julia 1.6.x](https://discourse.julialang.org/t/i-still-cant-use-julia-1-6-x/61345)

<div class="topic-metadata">

**Author:** [@HerAdri](https://discourse.julialang.org/u/HerAdri)\
**Replies:** 28\
**Last updated:** [May 25, 2021, 11:06am UTC](https://discourse.julialang.org/t/i-still-cant-use-julia-1-6-x/61345 "2021-05-25T11:06:56Z")

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Julia 1.6 corporate firewall Any news to solve this problem?

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## [KeyError: key "Xorg\_libXrender\_jll" not found](https://discourse.julialang.org/t/keyerror-key-xorg-libxrender-jll-not-found/61770)

<div class="topic-metadata">

**Author:** [@Aquaman](https://discourse.julialang.org/u/Aquaman)\
**Replies:** 0\
**Last updated:** [May 25, 2021, 10:22am UTC](https://discourse.julialang.org/t/keyerror-key-xorg-libxrender-jll-not-found/61770 "2021-05-25T10:22:24Z")

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I cannot install Plots.jl in Julia 1.6.1 due to the error “KeyError: key “Xorg\_libXrender\_jll” not found”

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## [Saving sparse matrix](https://discourse.julialang.org/t/saving-sparse-matrix/28089)

<div class="topic-metadata">

**Author:** [@saeed](https://discourse.julialang.org/u/saeed)\
**Replies:** 6\
**Last updated:** [May 25, 2021, 9:27am UTC](https://discourse.julialang.org/t/saving-sparse-matrix/28089 "2021-05-25T09:27:32Z")

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How to save a sparse matrix in Julia? I want the saved file to be small since my Matrix size is about (2^26,2^26). Thanks.

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## [Julia standard library for interval type](https://discourse.julialang.org/t/julia-standard-library-for-interval-type/60936)

<div class="topic-metadata">

**Author:** [@TheLateKronos](https://discourse.julialang.org/u/TheLateKronos)\
**Replies:** 22\
**Last updated:** [May 25, 2021, 8:26am UTC](https://discourse.julialang.org/t/julia-standard-library-for-interval-type/60936 "2021-05-25T08:26:14Z")

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I see the interval type, represented by e.g. 0..100 used in a few different areas. One is obviously for interval arithmetic. But using this notation/type/syntax also seems very usefor for e.g. setting plot limits. Anothe…

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## [Avoiding temporaries in hvcat with scalar functions](https://discourse.julialang.org/t/avoiding-temporaries-in-hvcat-with-scalar-functions/61759)

<div class="topic-metadata">

**Author:** [@pablosanjose](https://discourse.julialang.org/u/pablosanjose)\
**Replies:** 0\
**Last updated:** [May 25, 2021, 7:31am UTC](https://discourse.julialang.org/t/avoiding-temporaries-in-hvcat-with-scalar-functions/61759 "2021-05-25T07:31:17Z")

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Many times I need to build matrices by hvcating combinations of other matrices, for example M = \[ω\*I-A -D; -D' B-C\] for some general matrices A, B, C, D. Let’s assume they are dense (i.e. of type Matrix), but quite lar…

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## [JumpProblem with large number of jumps crashes](https://discourse.julialang.org/t/jumpproblem-with-large-number-of-jumps-crashes/61444)

<div class="topic-metadata">

**Author:** [@gzagatti](https://discourse.julialang.org/u/gzagatti)\
**Replies:** 13\
**Last updated:** [May 25, 2021, 8:00am UTC](https://discourse.julialang.org/t/jumpproblem-with-large-number-of-jumps-crashes/61444 "2021-05-25T08:00:06Z")

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Hello, I am trying to solve a JumpProblem defined on a network. The problem consists of a SIR model in which I am trying to model every node of the network separately. I have a working code that works with a small net…

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## [Adding vs multiplying matrices with DistributedArrays](https://discourse.julialang.org/t/adding-vs-multiplying-matrices-with-distributedarrays/61698)

<div class="topic-metadata">

**Author:** [@Debasish](https://discourse.julialang.org/u/Debasish)\
**Replies:** 7\
**Last updated:** [May 25, 2021, 7:34am UTC](https://discourse.julialang.org/t/adding-vs-multiplying-matrices-with-distributedarrays/61698 "2021-05-25T07:34:16Z")

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Hello everyone, I have a question regarding usage of distributed arrays. In preparation of a bigger calculation, I am doing a simple toy calculation to understand how distributed arrays works. Let me add 4 processors t…

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## [Aliases for \`=\` and \`==\`](https://discourse.julialang.org/t/aliases-for-and/60004)

<div class="topic-metadata">

**Author:** [@ParadaCarleton](https://discourse.julialang.org/u/ParadaCarleton)\
**Replies:** 43\
**Last updated:** [May 25, 2021, 7:21am UTC](https://discourse.julialang.org/t/aliases-for-and/60004 "2021-05-25T07:21:44Z")

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I think it makes sense to set := and =? as aliases for = and == respectively. The first one helps those coming from Python or Pascal, where := is valid syntax, and can also improve the readability of code. =? strikes me …

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