# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1645

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

**Page:** 1646

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## [Finding position of a sequence in a UInt8 array?](https://discourse.julialang.org/t/finding-position-of-a-sequence-in-a-uint8-array/45757)

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**Author:** [@Ahmed\_Salih](https://discourse.julialang.org/u/Ahmed_Salih)\
**Replies:** 11\
**Last updated:** [August 30, 2020, 2:18am UTC](https://discourse.julialang.org/t/finding-position-of-a-sequence-in-a-uint8-array/45757 "2020-08-30T02:18:44Z")

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Hello! Suppose I have: using Random rand(MersenneTwister(0),UInt8,10) 10-element Array{UInt8,1}: 0x40 0x52 0x99 0x35 0x90 0xea 0x00 0x13 0xdf 0x18 Say I want to find the position of sequence “0x90 0xea 0x…

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## [Using @nospecialize on a set of subtypes](https://discourse.julialang.org/t/using-nospecialize-on-a-set-of-subtypes/45655)

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**Author:** [@colintbowers](https://discourse.julialang.org/u/colintbowers)\
**Replies:** 4\
**Last updated:** [August 30, 2020, 1:09am UTC](https://discourse.julialang.org/t/using-nospecialize-on-a-set-of-subtypes/45655 "2020-08-30T01:09:51Z")

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Hi all, I have a function g(a,b) with many methods based on input types of a and b. A subset of the methods have common code, eg: g(a::T1, b::T2) where {T1\<:AbstractA,T2\<:AbstractB} = (fa(a),fb(b)) where fa and fb wil…

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## [Mapping LLVM type i1 to Julia type](https://discourse.julialang.org/t/mapping-llvm-type-i1-to-julia-type/45733)

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**Author:** [@msoeken](https://discourse.julialang.org/u/msoeken)\
**Replies:** 4\
**Last updated:** [August 29, 2020, 9:29pm UTC](https://discourse.julialang.org/t/mapping-llvm-type-i1-to-julia-type/45733 "2020-08-29T21:29:55Z")

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I am trying to use llvmcall and want to map a return value of LLVM type i1 to a Julia Bool value. using Base function isodd(a) Base.llvmcall("""%mod = srem i64 %0, 2\\n%cmp = icmp eq i64 %mod, 1\\nret i1 %cmp""", Boo…

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## [Param. estimation with different initial condition, how to do it?](https://discourse.julialang.org/t/param-estimation-with-different-initial-condition-how-to-do-it/45727)

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**Author:** [@Fred\_He](https://discourse.julialang.org/u/Fred_He)\
**Replies:** 3\
**Last updated:** [August 29, 2020, 8:34pm UTC](https://discourse.julialang.org/t/param-estimation-with-different-initial-condition-how-to-do-it/45727 "2020-08-29T20:34:53Z")

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Hello, I am new to DiffEqParamEstimation.jl package and trying to use it. The first thing I want to solve with this package is kinetic constant estimation based on plug flow model. It can be simplified to: However, I…

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## [Nonallocating readuntil functionality?](https://discourse.julialang.org/t/nonallocating-readuntil-functionality/45746)

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**Author:** [@Ahmed\_Salih](https://discourse.julialang.org/u/Ahmed_Salih)\
**Replies:** 1\
**Last updated:** [August 29, 2020, 7:56pm UTC](https://discourse.julialang.org/t/nonallocating-readuntil-functionality/45746 "2020-08-29T19:56:14Z")

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Hello! Using readuntil I found that it allocates (even though I have no need for it to do so). Reading on Github I found this post mentioning skipchars https://github.com/JuliaLang/julia/pull/36160 But in my case I ne…

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## [Fastest way to get started on a new machine](https://discourse.julialang.org/t/fastest-way-to-get-started-on-a-new-machine/45725)

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**Author:** [@mohamed82008](https://discourse.julialang.org/u/mohamed82008)\
**Replies:** 3\
**Last updated:** [August 29, 2020, 7:29pm UTC](https://discourse.julialang.org/t/fastest-way-to-get-started-on-a-new-machine/45725 "2020-08-29T19:29:27Z")

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Hi, I am curious what people’s recommended workflows for getting started on a new machine are, installing all the software and drivers you normally use. I am mostly interested in Linux but I am curious if better workflo…

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## [Arrays of structs/tuples with mutable members](https://discourse.julialang.org/t/arrays-of-structs-tuples-with-mutable-members/45754)

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**Author:** [@Stephen\_Vavasis](https://discourse.julialang.org/u/Stephen_Vavasis)\
**Replies:** 4\
**Last updated:** [August 29, 2020, 7:23pm UTC](https://discourse.julialang.org/t/arrays-of-structs-tuples-with-mutable-members/45754 "2020-08-29T19:23:11Z")

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I tested the performance of an array of tuples and structs in Julia 1.3.1 and 1.5.1 and am a bit confused about the results. There are eight separate times based on three choices: 1.3.1 vs 1.5.1, structs vs tuples, and …

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## [Passing values to function arguments using Dict?](https://discourse.julialang.org/t/passing-values-to-function-arguments-using-dict/45758)

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**Author:** [@varun7rs](https://discourse.julialang.org/u/varun7rs)\
**Replies:** 5\
**Last updated:** [August 29, 2020, 7:00pm UTC](https://discourse.julialang.org/t/passing-values-to-function-arguments-using-dict/45758 "2020-08-29T19:00:02Z")

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Hi, I have a problem where a function already defined in Julia has several keyword arguments. Now, to pass in values to these arguments, I’ve got to do something like the following dummyFn(3, 4; key1=6, key2=9, key3=6…

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## [Declaring Pair with one fixed type](https://discourse.julialang.org/t/declaring-pair-with-one-fixed-type/45756)

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**Author:** [@Josiah\_Slack](https://discourse.julialang.org/u/Josiah_Slack)\
**Replies:** 2\
**Last updated:** [August 29, 2020, 6:50pm UTC](https://discourse.julialang.org/t/declaring-pair-with-one-fixed-type/45756 "2020-08-29T18:50:16Z")

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Let’s say that I’d like to declare a function that takes a Pair as its argument, and that I’d like to restrict the kind of Pair that will be matched. For example: function foo(p::Pair{String,Any}) do some stuff end I…

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## [Proposal for automatic diagram creation system for Julia - Inspiration Penrose](https://discourse.julialang.org/t/proposal-for-automatic-diagram-creation-system-for-julia-inspiration-penrose/45750)

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**Author:** [@bradeneliason](https://discourse.julialang.org/u/bradeneliason)\
**Replies:** 1\
**Last updated:** [August 29, 2020, 6:31pm UTC](https://discourse.julialang.org/t/proposal-for-automatic-diagram-creation-system-for-julia-inspiration-penrose/45750 "2020-08-29T18:31:59Z")

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Penrose is a system under development which automatically creates math diagrams that would be suitable for a textbook directly from abstract mathematical specification. A simple example is creating Venn diagrams from set…

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## [LoopVectorization.jl: adding \`@avx\` makes code slower](https://discourse.julialang.org/t/loopvectorization-jl-adding-avx-makes-code-slower/45742)

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**Author:** [@ranocha](https://discourse.julialang.org/u/ranocha)\
**Replies:** 8\
**Last updated:** [August 29, 2020, 4:22pm UTC](https://discourse.julialang.org/t/loopvectorization-jl-adding-avx-makes-code-slower/45742 "2020-08-29T16:22:34Z")

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I am given a multi-dimensional Array and have to multiply it by an SMatrix along multiple dimensions. Using a straightforward approach in 2 dimensions, adding @avx from the great package LoopVectorization.jl increases th…

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## [VS Code Debugger include("bar.jl") "paused on exception"](https://discourse.julialang.org/t/vs-code-debugger-include-bar-jl-paused-on-exception/42779)

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**Author:** [@rdjconti](https://discourse.julialang.org/u/rdjconti)\
**Replies:** 4\
**Last updated:** [August 29, 2020, 4:00pm UTC](https://discourse.julialang.org/t/vs-code-debugger-include-bar-jl-paused-on-exception/42779 "2020-08-29T16:00:14Z")

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Hello, I try to debug the example from julia discourse foo() calls bar() but with bar() in a separate file bar.jl function bar(a, b) c = a + b; d = a \* b; return c + d end and the file main.jl include("b…

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## [The Julia Language joins NODES 2020 as a Community Partner](https://discourse.julialang.org/t/the-julia-language-joins-nodes-2020-as-a-community-partner/45749)

<div class="topic-metadata">

**Author:** [@logankilpatrick](https://discourse.julialang.org/u/logankilpatrick)\
**Replies:** 0\
**Last updated:** [August 29, 2020, 3:56pm UTC](https://discourse.julialang.org/t/the-julia-language-joins-nodes-2020-as-a-community-partner/45749 "2020-08-29T15:56:48Z")

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Hey all, We are proud to announce that the Julia Language will be a community partner for the upcoming NODES 2020 conference. “NODES 2020 is a free, one-day virtual conference loaded with highly technical presentations,…

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## [Working with dictionaries in @variables and @constraints](https://discourse.julialang.org/t/working-with-dictionaries-in-variables-and-constraints/45726)

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**Author:** [@sogrbilja](https://discourse.julialang.org/u/sogrbilja)\
**Replies:** 2\
**Last updated:** [August 29, 2020, 2:48pm UTC](https://discourse.julialang.org/t/working-with-dictionaries-in-variables-and-constraints/45726 "2020-08-29T14:48:43Z")

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I wonder if it is possible to work with Dict in @variables and @constraints like this: \_ORDER\_PRODUCTS and UNITS are Dict @constraint(premex, PRODAMOUNTint\_upper\[op in \_ORDER\_PRODUCTS, u in UNITS, t in TIME\], …

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## [Expressions for partial derivatives using AD tools](https://discourse.julialang.org/t/expressions-for-partial-derivatives-using-ad-tools/45741)

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**Author:** [@JLHTM](https://discourse.julialang.org/u/JLHTM)\
**Replies:** 2\
**Last updated:** [August 29, 2020, 1:53pm UTC](https://discourse.julialang.org/t/expressions-for-partial-derivatives-using-ad-tools/45741 "2020-08-29T13:53:51Z")

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I have two bivariate functions (more generally, n n-variable functions) f\_1(x\_1,x\_2) and f\_2(x\_1,x\_2). I need to solve the following system of equations: \\frac{\\partial f\_1}{\\partial x\_1} = 0 and \\frac{\\partial f\_2}{\\par…

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## [ERROR: MethodError: no method matching Model](https://discourse.julialang.org/t/error-methoderror-no-method-matching-model/45699)

<div class="topic-metadata">

**Author:** [@cotepascal76](https://discourse.julialang.org/u/cotepascal76)\
**Replies:** 2\
**Last updated:** [August 29, 2020, 10:34am UTC](https://discourse.julialang.org/t/error-methoderror-no-method-matching-model/45699 "2020-08-29T10:34:26Z")

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Hello, I’m new in Julia and JuMP and I just tried to install and test JuMP but I got this error (with all solvers that I tested): julia\> Model(Gurobi.Optimizer) ERROR: MethodError: no method matching Model(::Type{Gurob…

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## [What's your simple thing that you'd like to be easier than it is?](https://discourse.julialang.org/t/whats-your-simple-thing-that-youd-like-to-be-easier-than-it-is/45665)

<div class="topic-metadata">

**Author:** [@jules](https://discourse.julialang.org/u/jules)\
**Replies:** 22\
**Last updated:** [August 29, 2020, 9:49am UTC](https://discourse.julialang.org/t/whats-your-simple-thing-that-youd-like-to-be-easier-than-it-is/45665 "2020-08-29T09:49:13Z")

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I’m interested in a current overview of simple expressions often come up, but which tend to be more verbose or difficult than they could theoretically be. These things are scattered around many threads here and there but…

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## [Why does Zygote produce a wrong derivative?](https://discourse.julialang.org/t/why-does-zygote-produce-a-wrong-derivative/45724)

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**Author:** [@joachimbrand1](https://discourse.julialang.org/u/joachimbrand1)\
**Replies:** 5\
**Last updated:** [August 29, 2020, 9:06am UTC](https://discourse.julialang.org/t/why-does-zygote-produce-a-wrong-derivative/45724 "2020-08-29T09:06:32Z")

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Trying to get my head around AD in Julia and being inspired by Jarret Revels’ example of computing the Jacobian of a cumprod() function with ForwardDiff.jl, I tried to see whether I could get the same done with Zygote.…

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## [A quick proof-of-concept for a macro-less API for DataFrames that's easier to type](https://discourse.julialang.org/t/a-quick-proof-of-concept-for-a-macro-less-api-for-dataframes-thats-easier-to-type/45718)

<div class="topic-metadata">

**Author:** [@xiaodai](https://discourse.julialang.org/u/xiaodai)\
**Replies:** 1\
**Last updated:** [August 29, 2020, 8:34am UTC](https://discourse.julialang.org/t/a-quick-proof-of-concept-for-a-macro-less-api-for-dataframes-thats-easier-to-type/45718 "2020-08-29T08:34:03Z")

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I find the DataFrames.jl group-by syntax very sensible. For example using DataFrames df = DataFrame(grp = rand(1:8, 100), val = rand(100)) using Pipe @pipe df |\> groupby(\_, :grp) |\> combine(\_, :val =\> mean) The =…

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## [JuliaREPL at Github](https://discourse.julialang.org/t/juliarepl-at-github/45723)

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**Author:** [@bahasalien](https://discourse.julialang.org/u/bahasalien)\
**Replies:** 0\
**Last updated:** [August 29, 2020, 5:35am UTC](https://discourse.julialang.org/t/juliarepl-at-github/45723 "2020-08-29T05:35:27Z")

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Hello everyone! this is my first topic at Julia Community. i want to tell if you’re already make something improved outside Julia. maybe it was some a keybinding or julia as a base your another tools, a constructing jul…

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## [Creating an array of equations in ModelingToolkit](https://discourse.julialang.org/t/creating-an-array-of-equations-in-modelingtoolkit/45712)

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**Author:** [@zdenek\_hurak](https://discourse.julialang.org/u/zdenek_hurak)\
**Replies:** 2\
**Last updated:** [August 29, 2020, 2:53am UTC](https://discourse.julialang.org/t/creating-an-array-of-equations-in-modelingtoolkit/45712 "2020-08-29T02:53:04Z")

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I am trying to model a set of differential equations in ModelingToolkit. And I want to formulate it using vector variables. Namely, I will have a variable vector z = \[z₁, z₂, z₃\] (just a minimal example): julia\> using M…

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## [Computing Inverse of a stack of matrices](https://discourse.julialang.org/t/computing-inverse-of-a-stack-of-matrices/45580)

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**Author:** [@bhaveshshrimali](https://discourse.julialang.org/u/bhaveshshrimali)\
**Replies:** 19\
**Last updated:** [August 29, 2020, 2:52am UTC](https://discourse.julialang.org/t/computing-inverse-of-a-stack-of-matrices/45580 "2020-08-29T02:52:59Z")

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Hi everyone, Just started this morning with Julia after a long overdue-:slight\_smile: I was looking for an efficient way to invert a stack of 3x3 matrices. Coming from a python background it does seem that numpy.linalg…

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## [Symmetrical log plot](https://discourse.julialang.org/t/symmetrical-log-plot/45709)

<div class="topic-metadata">

**Author:** [@gideonsimpson](https://discourse.julialang.org/u/gideonsimpson)\
**Replies:** 1\
**Last updated:** [August 29, 2020, 2:22am UTC](https://discourse.julialang.org/t/symmetrical-log-plot/45709 "2020-08-29T02:22:33Z")

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Is there anyway to do a symmetrical log plot (i.e., in both positive and negative directions), through Plots.jl? I know matplotlib has this functionality.

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## [Latent Variables](https://discourse.julialang.org/t/latent-variables/45697)

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**Author:** [@Reg](https://discourse.julialang.org/u/Reg)\
**Replies:** 5\
**Last updated:** [August 29, 2020, 2:28am UTC](https://discourse.julialang.org/t/latent-variables/45697 "2020-08-29T02:28:56Z")

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I am struggling with this error for modeling latent variables using Turing MethodError: no method matching Normal(::Array{Float64,1}, ::Float64) My data generation code is using Distributions using Statistics, LinearA…

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## [Adding MORE packages can result in speedup (and other strangeness)](https://discourse.julialang.org/t/adding-more-packages-can-result-in-speedup-and-other-strangeness/45715)

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**Author:** [@Palli](https://discourse.julialang.org/u/Palli)\
**Replies:** 0\
**Last updated:** [August 29, 2020, 12:18am UTC](https://discourse.julialang.org/t/adding-more-packages-can-result-in-speedup-and-other-strangeness/45715 "2020-08-29T00:18:33Z")

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A. Speedup and lower memory use, adding the first package: $ julia -q julia\> @time using DataValues, CSVFiles, ExcelFiles, StatFiles, ParquetFiles, DataFrames, VegaLite 10.102168 seconds (14.07 M allocations: 842.677 …

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## [Trouble updating Pluto](https://discourse.julialang.org/t/trouble-updating-pluto/45649)

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**Author:** [@colinclout12](https://discourse.julialang.org/u/colinclout12)\
**Replies:** 6\
**Last updated:** [August 28, 2020, 11:49pm UTC](https://discourse.julialang.org/t/trouble-updating-pluto/45649 "2020-08-28T23:49:37Z")

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I’m having trouble updating Pluto, and I can’t figure out what’s wrong. (@v1.4) pkg\> update Pluto Updating registry at \`C:\\Users\\...\\.juliapro\\JuliaPro\_v1.4.2-1\\registries\\JuliaPro\` Updating \`C:\\Users\\...\\.juliapro\\…

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## [Vscode run file in repl terminal](https://discourse.julialang.org/t/vscode-run-file-in-repl-terminal/45656)

<div class="topic-metadata">

**Author:** [@RaulDurand](https://discourse.julialang.org/u/RaulDurand)\
**Replies:** 5\
**Last updated:** [August 28, 2020, 9:39pm UTC](https://discourse.julialang.org/t/vscode-run-file-in-repl-terminal/45656 "2020-08-28T21:39:23Z")

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Is there a way to run the current file in the current REPL terminal? Something that does \> include(“$currentfile”) in the REPL. I am aware of the command Run File, but it reloads packages each time and becomes slow. …

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## [Automatically generate docs for wrapped C libraries](https://discourse.julialang.org/t/automatically-generate-docs-for-wrapped-c-libraries/45671)

<div class="topic-metadata">

**Author:** [@serenity4](https://discourse.julialang.org/u/serenity4)\
**Replies:** 4\
**Last updated:** [August 28, 2020, 7:56pm UTC](https://discourse.julialang.org/t/automatically-generate-docs-for-wrapped-c-libraries/45671 "2020-08-28T19:56:25Z")

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Hi, I am wrapping a C library (XCB) with Clang, and I miss having docstrings around the wrapped library. I was wondering, is there a way to generate them automatically? Essentially, it would be interesting to have some …

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## [Data copying in Distributed computing](https://discourse.julialang.org/t/data-copying-in-distributed-computing/45704)

<div class="topic-metadata">

**Author:** [@Sheemon7](https://discourse.julialang.org/u/Sheemon7)\
**Replies:** 0\
**Last updated:** [August 28, 2020, 7:25pm UTC](https://discourse.julialang.org/t/data-copying-in-distributed-computing/45704 "2020-08-28T19:25:06Z")

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I have a perfectly parallelizable task, which I want to compute using several processes (threads are not applicable here). Say I want to pmap a function f, taking about 1-10 seconds over a vector A of 10M elements. The p…

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## [Why applying an integration algorithm to whole DAEs?](https://discourse.julialang.org/t/why-applying-an-integration-algorithm-to-whole-daes/45620)

<div class="topic-metadata">

**Author:** [@takunoda](https://discourse.julialang.org/u/takunoda)\
**Replies:** 3\
**Last updated:** [August 28, 2020, 7:04pm UTC](https://discourse.julialang.org/t/why-applying-an-integration-algorithm-to-whole-daes/45620 "2020-08-28T19:04:32Z")

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Let me ask a fundamental question which may be trivial to experts in this field. Compared with solving a set of ODEs, solving a set of DAEs is much more difficult. For instance, in the case of electrical circuits, the e…

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