# General Usage

**URL:** https://discourse.julialang.org/c/usage/6.md?page=512

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

**Page:** 513

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## [Point location library](https://discourse.julialang.org/t/point-location-library/55606)

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**Author:** [@Skoffer](https://discourse.julialang.org/u/Skoffer)\
**Replies:** 2\
**Last updated:** [December 3, 2021, 11:31am UTC](https://discourse.julialang.org/t/point-location-library/55606 "2021-12-03T11:31:28Z")

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Does anyone know, is there any Julia library for the Point Location problem? My search gave nothing, only this GEOS functions, but it looks like they are not exposed in LibGEOS.jl package. If there is no Julia package,…

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## [Understanding \`@eval\` help string and expressions](https://discourse.julialang.org/t/understanding-eval-help-string-and-expressions/72510)

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**Author:** [@danielw2904](https://discourse.julialang.org/u/danielw2904)\
**Replies:** 0\
**Last updated:** [December 3, 2021, 9:38am UTC](https://discourse.julialang.org/t/understanding-eval-help-string-and-expressions/72510 "2021-12-03T09:38:01Z")

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I came across this implementing the rotational cipher in exercism with the very nice help of @tomerarnon. The help for @eval states: @eval \[mod,\] ex Evaluate an expression with values interpolated into it using eval. …

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## [Project nested environments](https://discourse.julialang.org/t/project-nested-environments/72499)

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**Author:** [@jekyllstein](https://discourse.julialang.org/u/jekyllstein)\
**Replies:** 2\
**Last updated:** [December 3, 2021, 7:43am UTC](https://discourse.julialang.org/t/project-nested-environments/72499 "2021-12-03T07:43:52Z")

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I have a package with an examples folder inside of it. I want the examples folder to have its own Project.toml with things like Plots that I don’t want as dependencies in the package itself. I created an environment in t…

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## [Erratic test failure: difference between \]test and include(./test/runtests.jl)](https://discourse.julialang.org/t/erratic-test-failure-difference-between-test-and-include-test-runtests-jl/72342)

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**Author:** [@fipelle](https://discourse.julialang.org/u/fipelle)\
**Replies:** 8\
**Last updated:** [December 3, 2021, 3:28am UTC](https://discourse.julialang.org/t/erratic-test-failure-difference-between-test-and-include-test-runtests-jl/72342 "2021-12-03T03:28:50Z")

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Hi, I am having a strange problem with the tests of one of my packages, MessyTimeSeriesOptim.jl, which is currently under registration. I have cloned the dev branch on my laptop and added the package via Pkg.add(path="…

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## [JULIA matrix norm is different MATLAB](https://discourse.julialang.org/t/julia-matrix-norm-is-different-matlab/72500)

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**Author:** [@Sbeltranj](https://discourse.julialang.org/u/Sbeltranj)\
**Replies:** 6\
**Last updated:** [December 3, 2021, 3:24am UTC](https://discourse.julialang.org/t/julia-matrix-norm-is-different-matlab/72500 "2021-12-03T03:24:42Z")

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Hi, when I calculate the norm of vector a3, I get different values ​​in julia vs MatLab

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## [\`filter\` with \`eachrow\`](https://discourse.julialang.org/t/filter-with-eachrow/72466)

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**Author:** [@austinbean](https://discourse.julialang.org/u/austinbean)\
**Replies:** 5\
**Last updated:** [December 2, 2021, 11:28pm UTC](https://discourse.julialang.org/t/filter-with-eachrow/72466 "2021-12-02T23:28:02Z")

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Suppose I have an array with two columns. I want to filter the array based on the values of the first column, but would like what is returned by filter to include the second column. This method seems to be missing fro…

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## [Why is ccall syntax?](https://discourse.julialang.org/t/why-is-ccall-syntax/72427)

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**Author:** [@jzr](https://discourse.julialang.org/u/jzr)\
**Replies:** 8\
**Last updated:** [December 2, 2021, 11:12pm UTC](https://discourse.julialang.org/t/why-is-ccall-syntax/72427 "2021-12-02T23:12:13Z")

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ccall isn’t a function or macro but syntax. Why does it need to be syntax?

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## [General registry disappeared from 1.6 after updating to 1.7](https://discourse.julialang.org/t/general-registry-disappeared-from-1-6-after-updating-to-1-7/72485)

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**Author:** [@grahamas](https://discourse.julialang.org/u/grahamas)\
**Replies:** 2\
**Last updated:** [December 2, 2021, 7:23pm UTC](https://discourse.julialang.org/t/general-registry-disappeared-from-1-6-after-updating-to-1-7/72485 "2021-12-02T19:23:52Z")

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I updated to v1.7 yesterday and have been using it without issues since, but I just went back to v1.6 to test something, and found that Pkg doesn’t see the General registry (I also have a personal registry that is unaffe…

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## [When, exactly, is a Julia version released, and how can I tell?](https://discourse.julialang.org/t/when-exactly-is-a-julia-version-released-and-how-can-i-tell/72338)

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**Author:** [@Lilith](https://discourse.julialang.org/u/Lilith)\
**Replies:** 15\
**Last updated:** [December 2, 2021, 3:02pm UTC](https://discourse.julialang.org/t/when-exactly-is-a-julia-version-released-and-how-can-i-tell/72338 "2021-12-02T15:02:27Z")

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I’m developing a package to automatically update Julia, and uses https://julialang-s3.julialang.org/bin/versions.json from Download Julia as an official source for what versions are available. The discourse release annou…

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## [Porting Fortran code, negative indices](https://discourse.julialang.org/t/porting-fortran-code-negative-indices/72386)

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**Author:** [@baptnz](https://discourse.julialang.org/u/baptnz)\
**Replies:** 10\
**Last updated:** [December 2, 2021, 2:32pm UTC](https://discourse.julialang.org/t/porting-fortran-code-negative-indices/72386 "2021-12-02T14:32:04Z")

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I’m porting a low-level program from Fortran, and ideally I would only make minimal changes in the conversion (do loop becoming for kind of thing) to help track down any changes between the two versions. (Later on, once …

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## [How to find the nearest point on a grid?](https://discourse.julialang.org/t/how-to-find-the-nearest-point-on-a-grid/72402)

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**Author:** [@leon](https://discourse.julialang.org/u/leon)\
**Replies:** 10\
**Last updated:** [December 2, 2021, 2:07pm UTC](https://discourse.julialang.org/t/how-to-find-the-nearest-point-on-a-grid/72402 "2021-12-02T14:07:20Z")

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I have a grid defined as Lon = \[-180:0.25:180\]; Lat = \[-90:0.25:90\]; X, Y = meshgrid(Lon, Lat); I have many pairs of station data with corresponding longitude and latitude values and my goal is to find the nearest grid…

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## [DimensionMismatch("arrays could not be broadcast to a common size; )](https://discourse.julialang.org/t/dimensionmismatch-arrays-could-not-be-broadcast-to-a-common-size/72448)

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**Author:** [@FH96](https://discourse.julialang.org/u/FH96)\
**Replies:** 2\
**Last updated:** [December 2, 2021, 12:46pm UTC](https://discourse.julialang.org/t/dimensionmismatch-arrays-could-not-be-broadcast-to-a-common-size/72448 "2021-12-02T12:46:47Z")

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I’m trying to write a simple for loop!: for coef in reacions\_to\_test in which “reacions\_to\_test” is 2582-element Vector{Int64} but I face this error : DimensionMismatch("arrays could not be broadcast to a common size…

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## [Interrupting execution](https://discourse.julialang.org/t/interrupting-execution/72434)

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**Author:** [@jzr](https://discourse.julialang.org/u/jzr)\
**Replies:** 4\
**Last updated:** [December 2, 2021, 11:07am UTC](https://discourse.julialang.org/t/interrupting-execution/72434 "2021-12-02T11:07:14Z")

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I have read that julia only checks for IO and signals etc at certain points in the code. How was I able to interrupt this execution with ctrl-c? Where can I read the details? julia\> function f() while true …

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## [Calling fork](https://discourse.julialang.org/t/calling-fork/72410)

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**Author:** [@jzr](https://discourse.julialang.org/u/jzr)\
**Replies:** 2\
**Last updated:** [December 2, 2021, 10:18am UTC](https://discourse.julialang.org/t/calling-fork/72410 "2021-12-02T10:18:38Z")

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Julia has more sophisticated multi-processing tools but I want to experiment with some low level options. I expected this code to print the child pid from the parent and 0 from the child but it only prints from the paren…

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## ["plot not defined" and / or "twinx not defined"](https://discourse.julialang.org/t/plot-not-defined-and-or-twinx-not-defined/72435)

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**Author:** [@ellocco](https://discourse.julialang.org/u/ellocco)\
**Replies:** 6\
**Last updated:** [December 2, 2021, 9:41am UTC](https://discourse.julialang.org/t/plot-not-defined-and-or-twinx-not-defined/72435 "2021-12-02T09:41:36Z")

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Julia v1.7.0 I faced two issues: LoadError: UndefVarError: plot not defined and LoadError: UndefVarError: twinx not defined It took a while, how to achieve the result I was looking for. Below my simple example co…

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## [Extremely high first call latency Julia 1.6 versus 1.5 with multiphysics PDE solver](https://discourse.julialang.org/t/extremely-high-first-call-latency-julia-1-6-versus-1-5-with-multiphysics-pde-solver/71692)

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**Author:** [@amartinhuertas](https://discourse.julialang.org/u/amartinhuertas)\
**Replies:** 27\
**Last updated:** [December 2, 2021, 8:03am UTC](https://discourse.julialang.org/t/extremely-high-first-call-latency-julia-1-6-versus-1-5-with-multiphysics-pde-solver/71692 "2021-12-02T08:03:02Z")

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Dear all, we are experiencing extremely high first call latency times with Julia 1.6 when running our geophysical flows multiphysics finite element PDE solver (on the order of 15 hours on a supercomputer node with 192 G…

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## [Thank you, Thank you, Thank you](https://discourse.julialang.org/t/thank-you-thank-you-thank-you/72406)

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**Author:** [@lewis](https://discourse.julialang.org/u/lewis)\
**Replies:** 1\
**Last updated:** [December 2, 2021, 6:40am UTC](https://discourse.julialang.org/t/thank-you-thank-you-thank-you/72406 "2021-12-02T06:40:06Z")

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Just installed Julia 1.7 for Apple Binary. STUNNING. So incredibly fast on just “eye-balling” performance. Will do a couple unscientific benchmarks later. Plots to GR almost blits to the screen first time! Plots to p…

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## [Advent of Code 2021](https://discourse.julialang.org/t/advent-of-code-2021/72415)

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**Author:** [@stevensonmt](https://discourse.julialang.org/u/stevensonmt)\
**Replies:** 4\
**Last updated:** [December 2, 2021, 2:11am UTC](https://discourse.julialang.org/t/advent-of-code-2021/72415 "2021-12-02T02:11:46Z")

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Didn’t find a thread for Advent of Code 2021. This year I thought I’d use it to kickstart learning Julia. I plan to solve the exercises in Elixir and Julia. Last year I didn’t make it through to the end, hopefully this y…

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## [Floating point addition in Julia](https://discourse.julialang.org/t/floating-point-addition-in-julia/72341)

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**Author:** [@n90](https://discourse.julialang.org/u/n90)\
**Replies:** 6\
**Last updated:** [December 2, 2021, 1:54am UTC](https://discourse.julialang.org/t/floating-point-addition-in-julia/72341 "2021-12-02T01:54:33Z")

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I am a bit confused about the floating value addition in Julia. When I try to add two float values in Julia am getting a non rounded value with more precision. julia\> 106.8 + 1.085 107.88499999999999 I want to know if…

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## [Merging dataframes on dates](https://discourse.julialang.org/t/merging-dataframes-on-dates/72417)

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**Author:** [@Bruno322](https://discourse.julialang.org/u/Bruno322)\
**Replies:** 3\
**Last updated:** [December 1, 2021, 11:29pm UTC](https://discourse.julialang.org/t/merging-dataframes-on-dates/72417 "2021-12-01T23:29:25Z")

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I’m trying to clean a data set and I am stuck at the last step. The main dataframe, that I call maindf, will contain all the data and has 3000 rows and 200 columns, like this Each row of maindf will be filled with a…

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## [M1 vs. M1Pro vs. M1Max For DiffEq & Optim](https://discourse.julialang.org/t/m1-vs-m1pro-vs-m1max-for-diffeq-optim/72418)

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**Author:** [@donkeysaddle](https://discourse.julialang.org/u/donkeysaddle)\
**Replies:** 0\
**Last updated:** [December 1, 2021, 11:00pm UTC](https://discourse.julialang.org/t/m1-vs-m1pro-vs-m1max-for-diffeq-optim/72418 "2021-12-01T23:00:55Z")

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I think I will experience a performance boost with any of the Arm Macs but I was curious to hear people’s experiences particularly as it pertains to DifferentialEquations.jl and Optim.jl. My question is quite vague becau…

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## [Lift and @Lift generically](https://discourse.julialang.org/t/lift-and-lift-generically/72399)

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**Author:** [@Allan\_Baker](https://discourse.julialang.org/u/Allan_Baker)\
**Replies:** 3\
**Last updated:** [December 1, 2021, 8:40pm UTC](https://discourse.julialang.org/t/lift-and-lift-generically/72399 "2021-12-01T20:40:56Z")

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I have some routines that I used for calculations and simulation. Occasionally I want to use those same routines in a Makie GUI using observable Nodes and lift/@lift. In the past I have two versions of the plotting fun…

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## [New julia 1.7 install with jill: how transfer julia 1.6 packages (macos)](https://discourse.julialang.org/t/new-julia-1-7-install-with-jill-how-transfer-julia-1-6-packages-macos/72394)

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**Author:** [@murrayE](https://discourse.julialang.org/u/murrayE)\
**Replies:** 6\
**Last updated:** [December 1, 2021, 8:36pm UTC](https://discourse.julialang.org/t/new-julia-1-7-install-with-jill-how-transfer-julia-1-6-packages-macos/72394 "2021-12-01T20:36:45Z")

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Under macOS I had previously installed julia 1.6\* directly from Download Julia. This created ~/.julia/, which includes subdirectories config, environments, packages, and others. In particular, packages that I install go …

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## [Border Matrix in Pluto](https://discourse.julialang.org/t/border-matrix-in-pluto/72253)

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**Author:** [@Christopher\_Fisher](https://discourse.julialang.org/u/Christopher_Fisher)\
**Replies:** 4\
**Last updated:** [December 1, 2021, 7:21pm UTC](https://discourse.julialang.org/t/border-matrix-in-pluto/72253 "2021-12-01T19:21:14Z")

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Hi, I was wondering if it is possible to use a bordermatrix in Pluto? I tried the following without success: md" $M = \\bordermatrix{~ & x & y \\cr A & 1 & 0 \\cr B & 0 & 1 \\cr}$ "

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## [Makie Scatter Plot recipe for vector of custom types](https://discourse.julialang.org/t/makie-scatter-plot-recipe-for-vector-of-custom-types/72255)

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**Author:** [@Allan\_Baker](https://discourse.julialang.org/u/Allan_Baker)\
**Replies:** 5\
**Last updated:** [December 1, 2021, 7:05pm UTC](https://discourse.julialang.org/t/makie-scatter-plot-recipe-for-vector-of-custom-types/72255 "2021-12-01T19:05:14Z")

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This should be easy. At least it was for plots. I don’t understand what I am doing wrong. Looking for a simple example that shows me how to use convert\_arguments. I think the documentation makes too many assumptions …

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## [Huge performance fluctuations in parallel benchmark: insights?](https://discourse.julialang.org/t/huge-performance-fluctuations-in-parallel-benchmark-insights/67953)

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**Author:** [@lmiq](https://discourse.julialang.org/u/lmiq)\
**Replies:** 52\
**Last updated:** [December 1, 2021, 4:28pm UTC](https://discourse.julialang.org/t/huge-performance-fluctuations-in-parallel-benchmark-insights/67953 "2021-12-01T16:28:17Z")

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I have the following scenario. The function I am evaluating uses multi-threading, and it takes 5 to 6s to finish. But sometimes, to do exactly the same thing, it takes 2, 3 times that time. The machine is not running any…

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## [Multidimensional array syntax](https://discourse.julialang.org/t/multidimensional-array-syntax/72349)

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**Author:** [@johnh](https://discourse.julialang.org/u/johnh)\
**Replies:** 11\
**Last updated:** [December 1, 2021, 4:26pm UTC](https://discourse.julialang.org/t/multidimensional-array-syntax/72349 "2021-12-01T16:26:59Z")

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Are there any articles explaining the multidomensional array syntax at a level a complete idiot (me) can understand?

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## [Multi-threading or multi-processing, how to know which to use and when?](https://discourse.julialang.org/t/multi-threading-or-multi-processing-how-to-know-which-to-use-and-when/72278)

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**Author:** [@Lamma](https://discourse.julialang.org/u/Lamma)\
**Replies:** 32\
**Last updated:** [December 1, 2021, 3:23pm UTC](https://discourse.julialang.org/t/multi-threading-or-multi-processing-how-to-know-which-to-use-and-when/72278 "2021-12-01T15:23:52Z")

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I am wanting to run a simple for loop that is writing certain lines from a very large file to a new file based on a if check of pre computed criteria. reader = FASTA.Reader(GzipDecompressorStream(open("/home/people/robm…

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## [Error: Installing “julia-client@0.12.6” failed.](https://discourse.julialang.org/t/error-installing-julia-client-0-12-6-failed/72381)

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**Author:** [@glaicer](https://discourse.julialang.org/u/glaicer)\
**Replies:** 0\
**Last updated:** [December 1, 2021, 2:11pm UTC](https://discourse.julialang.org/t/error-installing-julia-client-0-12-6-failed/72381 "2021-12-01T14:11:35Z")

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Juno: Error installing package julia-client Please check your internet connection, or report this to https://github.com/JunoLab/Juno.jl/issues or https://discourse.julialang.org and we’ll try to help. Error: Installing…

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## [Braket symbol in Pluto does not work](https://discourse.julialang.org/t/braket-symbol-in-pluto-does-not-work/72376)

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**Author:** [@Christopher\_Fisher](https://discourse.julialang.org/u/Christopher_Fisher)\
**Replies:** 0\
**Last updated:** [December 1, 2021, 1:30pm UTC](https://discourse.julialang.org/t/braket-symbol-in-pluto-does-not-work/72376 "2021-12-01T13:30:39Z")

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Hi all, In the example below, the braket and contents are scrunched together. Am I doing something incorrect or is this a bug?

[Previous page](https://discourse.julialang.org/c/usage/6.md?page=511)

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