# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1657

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

**Page:** 1658

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## [Random \`invalid commands\` in gnuplot.jl when using vscode](https://discourse.julialang.org/t/random-invalid-commands-in-gnuplot-jl-when-using-vscode/45057)

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**Author:** [@affans](https://discourse.julialang.org/u/affans)\
**Replies:** 1\
**Last updated:** [August 16, 2020, 7:41pm UTC](https://discourse.julialang.org/t/random-invalid-commands-in-gnuplot-jl-when-using-vscode/45057 "2020-08-16T19:41:43Z")

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I am getting a weird error, and I can’t seem to reproduce it deterministically. From a fresh vscode julia repl, I select my code, and press ctrl-enter to execute it. It launches the REPL and runs the commands. I get the…

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## [Realistically, how close is Gaius.jl to becoming a full replacement for BLAS in Julia?](https://discourse.julialang.org/t/realistically-how-close-is-gaius-jl-to-becoming-a-full-replacement-for-blas-in-julia/42780)

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**Author:** [@xiaodai](https://discourse.julialang.org/u/xiaodai)\
**Replies:** 13\
**Last updated:** [August 16, 2020, 7:37pm UTC](https://discourse.julialang.org/t/realistically-how-close-is-gaius-jl-to-becoming-a-full-replacement-for-blas-in-julia/42780 "2020-08-16T19:37:06Z")

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https://github.com/MasonProtter/Gaius.jl I the above and is amazed. I always thought that BLAS, MKL etc are so complex and so well optimised that they are pretty much irreplaceable. Even if Gauis is slower for cases, h…

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## [Mutable struct pitfall](https://discourse.julialang.org/t/mutable-struct-pitfall/44996)

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**Author:** [@j2b2](https://discourse.julialang.org/u/j2b2)\
**Replies:** 17\
**Last updated:** [August 16, 2020, 5:17pm UTC](https://discourse.julialang.org/t/mutable-struct-pitfall/44996 "2020-08-16T17:17:58Z")

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julia\> mutable struct S x::Int end julia\> a = S(3) S(3) julia\> b = a S(3) julia\> b.x = 5 5 julia\> a S(5) Where is it documented ? Every computer scientist is aware of the risks when writing b = a, and then modifiying el…

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## [Plotting in Julia like Matlab plots](https://discourse.julialang.org/t/plotting-in-julia-like-matlab-plots/44997)

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**Author:** [@sriharitn](https://discourse.julialang.org/u/sriharitn)\
**Replies:** 8\
**Last updated:** [August 16, 2020, 4:39pm UTC](https://discourse.julialang.org/t/plotting-in-julia-like-matlab-plots/44997 "2020-08-16T16:39:47Z")

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I’m trying to plot 3D surface plot like the figure below (source: Wikipedia): Here is my attempt in julia; x = \[-2:0.05:2;\] y = \[-1:0.05:3;\] z = (1 .-x').^2 .+ 100 .\*(y.-x'.^2).^2 minZ = minimum(z\[:\]); maxZ = max…

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## [Arbitrary table join conditions](https://discourse.julialang.org/t/arbitrary-table-join-conditions/44825)

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**Author:** [@derekmahar](https://discourse.julialang.org/u/derekmahar)\
**Replies:** 9\
**Last updated:** [August 16, 2020, 12:47am UTC](https://discourse.julialang.org/t/arbitrary-table-join-conditions/44825 "2020-08-16T00:47:22Z")

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What Julia tabular data types and functions might I use in order to join two tables using a join condition that is more complex than simple equality between sets of columns in each table (an equi-join)? As far as I can …

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## [Slightly generalised \`accumulate\`](https://discourse.julialang.org/t/slightly-generalised-accumulate/45039)

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**Author:** [@willtebbutt](https://discourse.julialang.org/u/willtebbutt)\
**Replies:** 6\
**Last updated:** [August 16, 2020, 2:56pm UTC](https://discourse.julialang.org/t/slightly-generalised-accumulate/45039 "2020-08-16T14:56:16Z")

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accumulate (a.k.a. scan, prefix etc) is great, but I’ve got a situation in which I need something very slightly different, and wonder whether anyone knows whether it has a name someone has already implemented it Speci…

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## [Why is "macro" different from "function" if everything is an expression?](https://discourse.julialang.org/t/why-is-macro-different-from-function-if-everything-is-an-expression/45043)

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**Author:** [@greatpet](https://discourse.julialang.org/u/greatpet)\
**Replies:** 4\
**Last updated:** [August 16, 2020, 2:05pm UTC](https://discourse.julialang.org/t/why-is-macro-different-from-function-if-everything-is-an-expression/45043 "2020-08-16T14:05:00Z")

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I’m learning the basics of macros. Coming from another LISP-inspired language (Wolfram Mathematica), I’m wondering why there is a distinction between macros and functions. Isn’t a macro just a function whose argument is …

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## [Compilation of tips for speeding up computations](https://discourse.julialang.org/t/compilation-of-tips-for-speeding-up-computations/45033)

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**Author:** [@amrods](https://discourse.julialang.org/u/amrods)\
**Replies:** 1\
**Last updated:** [August 16, 2020, 1:10pm UTC](https://discourse.julialang.org/t/compilation-of-tips-for-speeding-up-computations/45033 "2020-08-16T13:10:47Z")

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Every now and then someone posts a question asking about why Matlab/Python/C/Fortran is so much faster than Julia. The great community here is quickly to point out optimizations that can be used which result in a signifi…

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## [Making vcat of splatted comprehension type-stable](https://discourse.julialang.org/t/making-vcat-of-splatted-comprehension-type-stable/43872)

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**Author:** [@HenriDeh](https://discourse.julialang.org/u/HenriDeh)\
**Replies:** 5\
**Last updated:** [August 16, 2020, 12:56pm UTC](https://discourse.julialang.org/t/making-vcat-of-splatted-comprehension-type-stable/43872 "2020-08-16T12:56:33Z")

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Hi, I am looking for a way to make this kind of operation type-stable. There are many uses to structs with lists of callables but I can’t seem to find a way to make the concatenation of their outputs type-stable julia\> …

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## [ERROR: LoadError: syntax: unexpected "\]"](https://discourse.julialang.org/t/error-loaderror-syntax-unexpected/45040)

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**Author:** [@mamo](https://discourse.julialang.org/u/mamo)\
**Replies:** 2\
**Last updated:** [August 16, 2020, 12:33pm UTC](https://discourse.julialang.org/t/error-loaderror-syntax-unexpected/45040 "2020-08-16T12:33:36Z")

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Help me please to identify the source of this error: ‘’'war\[k in 1:interval:length(TIME) if k\>=1+interval && k\<length(TIME)\], PL\[k\]==PL\[k-interval\]+sum(PROD\[o,f,p,j,t\] for o in O, f in F, p in PR\[f\], j in U, t in k:int…

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## [Correct constraint statement](https://discourse.julialang.org/t/correct-constraint-statement/45036)

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**Author:** [@mamo](https://discourse.julialang.org/u/mamo)\
**Replies:** 2\
**Last updated:** [August 16, 2020, 11:22am UTC](https://discourse.julialang.org/t/correct-constraint-statement/45036 "2020-08-16T11:22:59Z")

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In this constraint k goes from 1 to end but with step equal to in “interval” (scalar equal to 20 for example): ‘’‘rawmbal1\[r in RAW, k in 1…end by interval: k==1\], INV\[r,k\]=invraw\[r,k\]-sum(PRD\[o,f,p,j,t\]\*demraw\[p,r\] fo…

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## [ERROR: LoadError: syntax: invalid identifier name "&&"](https://discourse.julialang.org/t/error-loaderror-syntax-invalid-identifier-name/45034)

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**Author:** [@mamo](https://discourse.julialang.org/u/mamo)\
**Replies:** 3\
**Last updated:** [August 16, 2020, 10:55am UTC](https://discourse.julialang.org/t/error-loaderror-syntax-invalid-identifier-name/45034 "2020-08-16T10:55:46Z")

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Dear all, why it reports error with && in case below: sum((change\_cost\[k,l,j\]\*C\[k,l,j,t,t+1\]) for k in F, l in F, j in U, t in TIME: (t\<=length(TIME)-1) && (k != l)) Thanks!

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## [Indicator constraints](https://discourse.julialang.org/t/indicator-constraints/45030)

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**Author:** [@mamo](https://discourse.julialang.org/u/mamo)\
**Replies:** 0\
**Last updated:** [August 16, 2020, 9:34am UTC](https://discourse.julialang.org/t/indicator-constraints/45030 "2020-08-16T09:34:29Z")

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This is an indicator constraint: cl23\[(f1,f2) in FO, j in U, t in TIME: t\<=end-15\], CL1\[f1,f2,j,t\]=0 ==\> FAS\[f1,j,t\]+FASa\[f2,j\]\<=1 is it possible for GLPK or CBC to handle it or should be transformed? Thanks, Marco

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## [How to reduce memory allocation when looping over an array?](https://discourse.julialang.org/t/how-to-reduce-memory-allocation-when-looping-over-an-array/45022)

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**Author:** [@niashvili](https://discourse.julialang.org/u/niashvili)\
**Replies:** 2\
**Last updated:** [August 16, 2020, 5:47am UTC](https://discourse.julialang.org/t/how-to-reduce-memory-allocation-when-looping-over-an-array/45022 "2020-08-16T05:47:23Z")

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Hi guys, I have one main question with a given example and a couple other ones related to understanding some concepts. First, here’s the example function: function brownian\_paths(; paths=10^3, n=10^5, t=1, S0=100, μ=(S…

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## [Is there a pgkdown equivalent in Julia for generating websites for packages?](https://discourse.julialang.org/t/is-there-a-pgkdown-equivalent-in-julia-for-generating-websites-for-packages/45025)

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**Author:** [@xiaodai](https://discourse.julialang.org/u/xiaodai)\
**Replies:** 1\
**Last updated:** [August 16, 2020, 6:52am UTC](https://discourse.julialang.org/t/is-there-a-pgkdown-equivalent-in-julia-for-generating-websites-for-packages/45025 "2020-08-16T06:52:59Z")

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I see there is PkgPage.jl which generates a front page for a package. I wonder if there is a package that can glean all the function docs and generate document pages in Franklin.jl as well. The example in R is {pkgdown}…

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## [Juno doesn't allow block execution when I change project path](https://discourse.julialang.org/t/juno-doesnt-allow-block-execution-when-i-change-project-path/45014)

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**Author:** [@DShiu](https://discourse.julialang.org/u/DShiu)\
**Replies:** 1\
**Last updated:** [August 16, 2020, 3:54am UTC](https://discourse.julialang.org/t/juno-doesnt-allow-block-execution-when-i-change-project-path/45014 "2020-08-16T03:54:40Z")

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My code becomes colorless and “Command+return” no longer executes a selected line of code. The code works if I run it in REPL.

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## [Difference between Julia Coroutines, Multithreading, Multicore](https://discourse.julialang.org/t/difference-between-julia-coroutines-multithreading-multicore/44986)

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**Author:** [@Palamedes](https://discourse.julialang.org/u/Palamedes)\
**Replies:** 3\
**Last updated:** [August 16, 2020, 3:51am UTC](https://discourse.julialang.org/t/difference-between-julia-coroutines-multithreading-multicore/44986 "2020-08-16T03:51:44Z")

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Hola what are the differences between Julias Courotines (Green Threading), Multi-Threading and Multi-Core/Distributed Processing? Distributed is distributed over different machines. But what is the difference between c…

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## [Cannot run parallel for loop when calling R code](https://discourse.julialang.org/t/cannot-run-parallel-for-loop-when-calling-r-code/45017)

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**Author:** [@PatrickXie17](https://discourse.julialang.org/u/PatrickXie17)\
**Replies:** 4\
**Last updated:** [August 16, 2020, 3:17am UTC](https://discourse.julialang.org/t/cannot-run-parallel-for-loop-when-calling-r-code/45017 "2020-08-16T03:17:05Z")

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Hi, I am recently moving my projects from R to Julia, and part of the code still relies on some R packages. I encountered problems when putting the R code inside the parallel for loop by using Threads.@threads. Below is …

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## [Does DiffEqFlux.jl supports a constrained optimal control problem, where in both control and states are constrained](https://discourse.julialang.org/t/does-diffeqflux-jl-supports-a-constrained-optimal-control-problem-where-in-both-control-and-states-are-constrained/44246)

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**Author:** [@manvibharat](https://discourse.julialang.org/u/manvibharat)\
**Replies:** 3\
**Last updated:** [August 16, 2020, 1:38am UTC](https://discourse.julialang.org/t/does-diffeqflux-jl-supports-a-constrained-optimal-control-problem-where-in-both-control-and-states-are-constrained/44246 "2020-08-16T01:38:14Z")

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I am new to Julia and I am still learning the language. I thought I could use Julia to solve an Optimal Control problem, which has some constraints. I looked at two examples I found at Readme · DiffEqFlux.jl and https:…

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## [Problems in use symbolic math](https://discourse.julialang.org/t/problems-in-use-symbolic-math/44957)

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**Author:** [@angeloaliano1](https://discourse.julialang.org/u/angeloaliano1)\
**Replies:** 24\
**Last updated:** [August 15, 2020, 9:52pm UTC](https://discourse.julialang.org/t/problems-in-use-symbolic-math/44957 "2020-08-15T21:52:21Z")

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I am trying to use SymPy package to deal with symbolic math. For example: using SymPy x, y, z = symbols("x y z") z=(x^2+y^2)/(y^2+1); However, the error appears: x, y, z = symbols("x y z") ERROR: ArgumentError: ref of…

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## [Error golfing!](https://discourse.julialang.org/t/error-golfing/45003)

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**Author:** [@Evey](https://discourse.julialang.org/u/Evey)\
**Replies:** 4\
**Last updated:** [August 15, 2020, 10:12pm UTC](https://discourse.julialang.org/t/error-golfing/45003 "2020-08-15T22:12:24Z")

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Hi Julians! This is a fun and stress-free challenge for anyone who wishes to become more familiar with … ERRORS. In Control Flow · The Julia Language there are 25 exceptions. Your job is to write code that throws all …

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## [Can't compile DiffEqParamEstim](https://discourse.julialang.org/t/cant-compile-diffeqparamestim/45004)

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**Author:** [@Sanji\_Vinsmoke](https://discourse.julialang.org/u/Sanji_Vinsmoke)\
**Replies:** 3\
**Last updated:** [August 15, 2020, 9:59pm UTC](https://discourse.julialang.org/t/cant-compile-diffeqparamestim/45004 "2020-08-15T21:59:57Z")

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Hi, I can’t compile DiffEqParamEstim in my PC. when I typed using DiffEqParamEsitm for the first time, I got \[ Info: Precompiling DiffEqParamEstim \[1130ab10-4a5a-5621-a13d-e4788d82bd4c\] WARNING: could not import Lea…

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## [Constraints with for loop and if statements](https://discourse.julialang.org/t/constraints-with-for-loop-and-if-statements/45009)

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**Author:** [@Micah\_Mungal](https://discourse.julialang.org/u/Micah_Mungal)\
**Replies:** 1\
**Last updated:** [August 15, 2020, 9:00pm UTC](https://discourse.julialang.org/t/constraints-with-for-loop-and-if-statements/45009 "2020-08-15T21:00:27Z")

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Hi, I am new to Julia and by extension JuMP. I am trying to rewrite a model for an optimization problem from Matlab to Julia using JuMP. Now following the documentation on the JuMP webpage, I have some doubts about writi…

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## [\[ANN\] Lints.jl - easy, high performance integrals for quantum chemistry](https://discourse.julialang.org/t/ann-lints-jl-easy-high-performance-integrals-for-quantum-chemistry/45011)

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**Author:** [@Matt\_Davis](https://discourse.julialang.org/u/Matt_Davis)\
**Replies:** 2\
**Last updated:** [August 15, 2020, 8:30pm UTC](https://discourse.julialang.org/t/ann-lints-jl-easy-high-performance-integrals-for-quantum-chemistry/45011 "2020-08-15T20:30:53Z")

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Hello! I am pleased to announce the first\* release of Lints.jl, a wrapper around the Libint2 Gaussian molecular integral library. \*first meant for use by anyone else is v0.2.0 Molecular integrals are required in qua…

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## [Pluto's running script with Julia shipping bundle](https://discourse.julialang.org/t/plutos-running-script-with-julia-shipping-bundle/44982)

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**Author:** [@DIzer](https://discourse.julialang.org/u/DIzer)\
**Replies:** 3\
**Last updated:** [August 15, 2020, 8:05pm UTC](https://discourse.julialang.org/t/plutos-running-script-with-julia-shipping-bundle/44982 "2020-08-15T20:05:05Z")

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If I am not mistaken Pluto.jl goes with Julia v 1.5… may be it is worthy to provide a script for running it “from the box”

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## [Parameters in DiffEqFlux](https://discourse.julialang.org/t/parameters-in-diffeqflux/44959)

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**Author:** [@colinclout12](https://discourse.julialang.org/u/colinclout12)\
**Replies:** 2\
**Last updated:** [August 15, 2020, 7:59pm UTC](https://discourse.julialang.org/t/parameters-in-diffeqflux/44959 "2020-08-15T19:59:19Z")

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I’m having trouble understanding how to enter the trainable parameters into DiffEqFlux. In order to understand how DiffEqFlux works, I set myself the following exercise: Replace p = \[1.5, 1.0, 3.0, 1.0\] in the example o…

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## [Repl.it Jam: If you knew then what you know now](https://discourse.julialang.org/t/repl-it-jam-if-you-knew-then-what-you-know-now/44905)

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**Author:** [@anon67531922](https://discourse.julialang.org/u/anon67531922)\
**Replies:** 10\
**Last updated:** [August 15, 2020, 7:24pm UTC](https://discourse.julialang.org/t/repl-it-jam-if-you-knew-then-what-you-know-now/44905 "2020-08-15T19:24:50Z")

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Hi, Julia development began in 2009 with the first public release in 2012 (according to Wikipedia). A lot has happened in the past 10+ years. Surely, there is some legacy already baked into the code base. I’m kind of cu…

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## [Julia v1.5.0 has been released](https://discourse.julialang.org/t/julia-v1-5-0-has-been-released/44169)

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**Author:** [@ararslan](https://discourse.julialang.org/u/ararslan)\
**Replies:** 38\
**Last updated:** [August 15, 2020, 7:21pm UTC](https://discourse.julialang.org/t/julia-v1-5-0-has-been-released/44169 "2020-08-15T19:21:42Z")

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Thank you to everyone who made this year’s JuliaCon great! As a parting gift, the Julia developers are pleased to announce the release of Julia v1.5.0, the fifth minor release in the 1.x series. Jeff and Stefan put toget…

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## [Is it worth to use Julia when you need several external non-Julia libraries?](https://discourse.julialang.org/t/is-it-worth-to-use-julia-when-you-need-several-external-non-julia-libraries/44991)

<div class="topic-metadata">

**Author:** [@ogreyesp](https://discourse.julialang.org/u/ogreyesp)\
**Replies:** 13\
**Last updated:** [August 15, 2020, 6:58pm UTC](https://discourse.julialang.org/t/is-it-worth-to-use-julia-when-you-need-several-external-non-julia-libraries/44991 "2020-08-15T18:58:34Z")

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Suppose that I want to develop a project, but several features that I need does not still exist in Julia and I must to use several R libraries (let’s say that about 60-70% of the logic of my project lies in the R librari…

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## [\`multiplot\` not working in Gnuplot.jl](https://discourse.julialang.org/t/multiplot-not-working-in-gnuplot-jl/44909)

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**Author:** [@affans](https://discourse.julialang.org/u/affans)\
**Replies:** 7\
**Last updated:** [August 15, 2020, 6:40pm UTC](https://discourse.julialang.org/t/multiplot-not-working-in-gnuplot-jl/44909 "2020-08-15T18:40:57Z")

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Extreme beginner in Gnuplot, and trying to put a multiplot together. The code below is directly from the examples from the doc # Generate random numbers x = randn(1000); y = randn(1000); # Overall plot margins (normal…

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