# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1909

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

**Page:** 1910

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## [Error I don't understand involving infix operator](https://discourse.julialang.org/t/error-i-dont-understand-involving-infix-operator/29212)

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**Author:** [@klaff](https://discourse.julialang.org/u/klaff)\
**Replies:** 11\
**Last updated:** [October 3, 2019, 11:53pm UTC](https://discourse.julialang.org/t/error-i-dont-understand-involving-infix-operator/29212 "2019-10-03T23:53:01Z")

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So, I defined a function like so (using \\parallel): julia\> ∥(a,b) = 1/(1/a+1/b) ∥ (generic function with 1 method) julia\> ∥(10,10) 5.0 julia\> 10∥10 5.0 julia\> 10∥10∥10 ERROR: TypeError: non-boolean (Float64) used in …

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## [How to add a constraint in a JuMP model using the obj function of another JuMP model](https://discourse.julialang.org/t/how-to-add-a-constraint-in-a-jump-model-using-the-obj-function-of-another-jump-model/29432)

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**Author:** [@Mahbubar06](https://discourse.julialang.org/u/Mahbubar06)\
**Replies:** 8\
**Last updated:** [October 3, 2019, 10:10pm UTC](https://discourse.julialang.org/t/how-to-add-a-constraint-in-a-jump-model-using-the-obj-function-of-another-jump-model/29432 "2019-10-03T22:10:33Z")

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Hello, I have the following JuMP model: using JuMP using MathProgBase using Ipopt model=Model(solver=IpoptSolver()) @variable(model, -100 \<= x\[1:5\] \<=100) @constraint(model, sum(x\[i\] for i in 1:5) \<= 50) @NLconstraint(…

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## [Serious performance issue with MySQL.jl](https://discourse.julialang.org/t/serious-performance-issue-with-mysql-jl/29289)

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**Author:** [@Sh4pe](https://discourse.julialang.org/u/Sh4pe)\
**Replies:** 2\
**Last updated:** [October 3, 2019, 9:31pm UTC](https://discourse.julialang.org/t/serious-performance-issue-with-mysql-jl/29289 "2019-10-03T21:31:24Z")

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Hi there! I hope that any MySQL.jl experts are out there. I’ve posted this issue already as #130 there and I hope to increase visibility by adding a topic here as well. In this test on my fork of MySQL.jl, I’ve managed…

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## [Seeking JuliaCon 2020 leadership for Diversity and Social efforts](https://discourse.julialang.org/t/seeking-juliacon-2020-leadership-for-diversity-and-social-efforts/29461)

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**Author:** [@xorJane](https://discourse.julialang.org/u/xorJane)\
**Replies:** 0\
**Last updated:** [October 3, 2019, 7:04pm UTC](https://discourse.julialang.org/t/seeking-juliacon-2020-leadership-for-diversity-and-social-efforts/29461 "2019-10-03T19:04:45Z")

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Hi all! We’re still looking for JuliaCon 2020 Diversity and Social chairs. Descriptions of these positions are included at the top of the form here, where you can apply. Thank you!

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## [Evaluating Expr Error: UndefVarError: = not defined](https://discourse.julialang.org/t/evaluating-expr-error-undefvarerror-not-defined/29458)

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**Author:** [@Alex\_Ellison](https://discourse.julialang.org/u/Alex_Ellison)\
**Replies:** 4\
**Last updated:** [October 3, 2019, 6:36pm UTC](https://discourse.julialang.org/t/evaluating-expr-error-undefvarerror-not-defined/29458 "2019-10-03T18:36:24Z")

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With a hand-crafted Expr, I can initialize a new variable like so: julia\> a = :(x=1) :(x = 1) julia\> eval(a) 1 julia\> x 1 julia\> However, if I evaluate a comparably simple Expr generated from the Reduce algebra lib…

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## [SimpleANOVA v0.4.0](https://discourse.julialang.org/t/simpleanova-v0-4-0/28661)

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**Author:** [@BioTurboNick](https://discourse.julialang.org/u/BioTurboNick)\
**Replies:** 1\
**Last updated:** [October 3, 2019, 5:28pm UTC](https://discourse.julialang.org/t/simpleanova-v0-4-0/28661 "2019-10-03T17:28:01Z")

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Just putting out a new version of my SimpleANOVA package, now with Levene’s test baked in. Just waiting for the registry merge. https://github.com/BioTurboNick/SimpleANOVA.jl Use at own risk, but I’m using it for my ow…

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## [Popfirst!() on an array](https://discourse.julialang.org/t/popfirst-on-an-array/29456)

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**Author:** [@squirrel](https://discourse.julialang.org/u/squirrel)\
**Replies:** 4\
**Last updated:** [October 3, 2019, 5:19pm UTC](https://discourse.julialang.org/t/popfirst-on-an-array/29456 "2019-10-03T17:19:28Z")

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How efficient is popfirst!() on an Array compared to pop!()? If I use popfirst!() do all of the elements in the array need to be shifted over? If they do need shifting, it would need to read through the entire array. A…

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## [Error iterating MutableLinkedList](https://discourse.julialang.org/t/error-iterating-mutablelinkedlist/29455)

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**Author:** [@squirrel](https://discourse.julialang.org/u/squirrel)\
**Replies:** 1\
**Last updated:** [October 3, 2019, 4:03pm UTC](https://discourse.julialang.org/t/error-iterating-mutablelinkedlist/29455 "2019-10-03T16:03:05Z")

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I’m new to this. Is this an error in the DataStructurs.jl, or am I doing something wrong? julia\> using DataStructures julia\> animals = MutableLinkedList{String}("cat", "dog", "fish", "mouse") MutableLinkedList{String}(…

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## [Forbidden range for a variable of a LP](https://discourse.julialang.org/t/forbidden-range-for-a-variable-of-a-lp/29071)

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**Author:** [@jayce\_ram](https://discourse.julialang.org/u/jayce_ram)\
**Replies:** 6\
**Last updated:** [October 3, 2019, 3:01pm UTC](https://discourse.julialang.org/t/forbidden-range-for-a-variable-of-a-lp/29071 "2019-10-03T15:01:29Z")

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I would like to express a linear program having a variable that can only be greater or equal than a constant P or equal to 0. Like : x≥P or x=0 I know I could express it as a mixed integer problem but I really need to …

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## [DataFrames: reading vector from \*.csv file to dataframe column](https://discourse.julialang.org/t/dataframes-reading-vector-from-csv-file-to-dataframe-column/29409)

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**Author:** [@mike\_k](https://discourse.julialang.org/u/mike_k)\
**Replies:** 2\
**Last updated:** [October 3, 2019, 12:59pm UTC](https://discourse.julialang.org/t/dataframes-reading-vector-from-csv-file-to-dataframe-column/29409 "2019-10-03T12:59:29Z")

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Dear community, I want to read a csv file with several values including vectors to a data frame. My file looks like: myInt; myString; myVec 1 ; foo ; \[1,2,3\] The column myVec is, however, interpreted as string …

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## [R2 Montreal is hiring: Julia Data Science Developper](https://discourse.julialang.org/t/r2-montreal-is-hiring-julia-data-science-developper/28949)

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**Author:** [@sbR2](https://discourse.julialang.org/u/sbR2)\
**Replies:** 9\
**Last updated:** [October 3, 2019, 12:45pm UTC](https://discourse.julialang.org/t/r2-montreal-is-hiring-julia-data-science-developper/28949 "2019-10-03T12:45:54Z")

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Send resume to said.berriah@r2.ca As a Core Data Science Developer, you will work on building the software components of a distributed data science /machine learning system. In this role, you will collaborate very clos…

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## [Converting string to concrete type](https://discourse.julialang.org/t/converting-string-to-concrete-type/29434)

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**Author:** [@MaxPauer](https://discourse.julialang.org/u/MaxPauer)\
**Replies:** 6\
**Last updated:** [October 3, 2019, 12:25pm UTC](https://discourse.julialang.org/t/converting-string-to-concrete-type/29434 "2019-10-03T12:25:07Z")

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Suppose I have an abstract type, and some concrete types, that are easily converted to strings. For simplicity, let’s make them tag types. abstract type AbstractTag end struct TagA \<: AbstractTag end struct TagB \<: Ab…

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## [Unexpected behaviour in nested DefaultDicts](https://discourse.julialang.org/t/unexpected-behaviour-in-nested-defaultdicts/29440)

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**Author:** [@PaulMainwood](https://discourse.julialang.org/u/PaulMainwood)\
**Replies:** 1\
**Last updated:** [October 3, 2019, 10:59am UTC](https://discourse.julialang.org/t/unexpected-behaviour-in-nested-defaultdicts/29440 "2019-10-03T10:59:50Z")

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I am using a structure where I want to use nested DefaultDicts. The outer one, I want to default to an empty DefaultDict, which in turn I want to have a default value of 1.0. julia\> d = DefaultDict{Int64, DefaultDict}(D…

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## [What exactly is this XML\_Parse in the LibExpat package?](https://discourse.julialang.org/t/what-exactly-is-this-xml-parse-in-the-libexpat-package/29399)

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**Author:** [@bsnyh](https://discourse.julialang.org/u/bsnyh)\
**Replies:** 1\
**Last updated:** [October 3, 2019, 12:11pm UTC](https://discourse.julialang.org/t/what-exactly-is-this-xml-parse-in-the-libexpat-package/29399 "2019-10-03T12:11:15Z")

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Hi, I hope this is not a too naive question. I get confused about “XML\_Parse” in LibExpat package. The following is the function where it is actually used. function parsefile(filename::AbstractString,callbacks::XPCallb…

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## [Streaming large xml files using LibExpat package downloaded from GitHub](https://discourse.julialang.org/t/streaming-large-xml-files-using-libexpat-package-downloaded-from-github/25254)

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**Author:** [@bsnyh](https://discourse.julialang.org/u/bsnyh)\
**Replies:** 1\
**Last updated:** [October 3, 2019, 12:09pm UTC](https://discourse.julialang.org/t/streaming-large-xml-files-using-libexpat-package-downloaded-from-github/25254 "2019-10-03T12:09:27Z")

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Hi, I was trying to figure out the source code of the LibExpat package. The following is the part which confuses me. mutable struct XPCallbacks start\_cdata::Function end\_cdata::Function comment:…

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## [Type inference on an array of arrays](https://discourse.julialang.org/t/type-inference-on-an-array-of-arrays/29439)

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**Author:** [@HenrikM](https://discourse.julialang.org/u/HenrikM)\
**Replies:** 2\
**Last updated:** [October 3, 2019, 11:57am UTC](https://discourse.julialang.org/t/type-inference-on-an-array-of-arrays/29439 "2019-10-03T11:57:56Z")

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Hello, could you please help me to understand the following code. I think the types line up really nicely, but Julia 1.2 thinks otherwise. d = 2 a1 = \[0.0\] a2 = \[0.0\] b1 = zeros(d, 1) b2 = zeros(d, 1) c1 = \[0.0\] c2 = \[0…

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## [JuMP optimization with registered function](https://discourse.julialang.org/t/jump-optimization-with-registered-function/29445)

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**Author:** [@Matthew\_Overlin](https://discourse.julialang.org/u/Matthew_Overlin)\
**Replies:** 0\
**Last updated:** [October 3, 2019, 11:14am UTC](https://discourse.julialang.org/t/jump-optimization-with-registered-function/29445 "2019-10-03T11:14:53Z")

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I am trying to use JuMP for parameter estimation. In my julia script, I have a line “JuMP.register(model, :fun\_to\_min, 24, fun\_to\_min, autodiff=true);” That is, I have “fun\_to\_min” which takes 24 parameters and returns…

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## [Testing on Travis with nightly/Windows 64-bit doesn't work](https://discourse.julialang.org/t/testing-on-travis-with-nightly-windows-64-bit-doesnt-work/29441)

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**Author:** [@PetrKryslUCSD](https://discourse.julialang.org/u/PetrKryslUCSD)\
**Replies:** 1\
**Last updated:** [October 3, 2019, 10:34am UTC](https://discourse.julialang.org/t/testing-on-travis-with-nightly-windows-64-bit-doesnt-work/29441 "2019-10-03T10:34:17Z")

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1.31s$ git clone --depth=50 --branch=master https://github.com/PetrKryslUCSD/FinEtools.jl.git PetrKryslUCSD/FinEtools.jl 0.08s Setting environment variables from repository settings $ export DOCUMENTER\_KEY=\[secure\] $ exp…

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## [Pkg installs Homebrew to a Linux box as a dependency](https://discourse.julialang.org/t/pkg-installs-homebrew-to-a-linux-box-as-a-dependency/29438)

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**Author:** [@KajWiik](https://discourse.julialang.org/u/KajWiik)\
**Replies:** 1\
**Last updated:** [October 3, 2019, 9:25am UTC](https://discourse.julialang.org/t/pkg-installs-homebrew-to-a-linux-box-as-a-dependency/29438 "2019-10-03T09:25:40Z")

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@jheinen noticed in Fastest way to draw on Gtk.jl 'canvas' with plots produced from Plots.jl? - #12 by jheinen that Homebrew is installed automatically as a dependency even if running in Linux OS. I tested this with a f…

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## [Parallel DataFrame processing](https://discourse.julialang.org/t/parallel-dataframe-processing/29397)

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**Author:** [@Fred](https://discourse.julialang.org/u/Fred)\
**Replies:** 2\
**Last updated:** [October 3, 2019, 9:07am UTC](https://discourse.julialang.org/t/parallel-dataframe-processing/29397 "2019-10-03T09:07:43Z")

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Hi ! I try to process DataFrame columns in parallel. I first think using pmap() but it was not possible because it is not just applying a function to each columns. So I created a toy example here producing my error. It…

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## [Support for test/dev/staging/prod deps environments in Pkg](https://discourse.julialang.org/t/support-for-test-dev-staging-prod-deps-environments-in-pkg/29437)

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**Author:** [@essenciary](https://discourse.julialang.org/u/essenciary)\
**Replies:** 0\
**Last updated:** [October 3, 2019, 8:58am UTC](https://discourse.julialang.org/t/support-for-test-dev-staging-prod-deps-environments-in-pkg/29437 "2019-10-03T08:58:20Z")

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I’ve been tweaking a lot with PackageCompiler this week and the issue which consistently broke all my attempts to use PackageCompiler is that the tests of the packages that PackageCompiler works with include dependencies…

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## [ANN: new version of package for Piecewise Deterministic Markov Processes](https://discourse.julialang.org/t/ann-new-version-of-package-for-piecewise-deterministic-markov-processes/29425)

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**Author:** [@rveltz](https://discourse.julialang.org/u/rveltz)\
**Replies:** 0\
**Last updated:** [October 2, 2019, 9:38pm UTC](https://discourse.julialang.org/t/ann-new-version-of-package-for-piecewise-deterministic-markov-processes/29425 "2019-10-02T21:38:10Z")

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Hi, I am happy to announce a new version of the package PiecewiseDeterministicMarkovProcesses.jl to simulate ODE with stochastic jumps. A lot of effort has been put to remove unncessary allocations, to make it fast an…

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## [Solve\_time is not working - JuMP](https://discourse.julialang.org/t/solve-time-is-not-working-jump/29062)

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**Author:** [@jayce\_ram](https://discourse.julialang.org/u/jayce_ram)\
**Replies:** 13\
**Last updated:** [October 3, 2019, 8:01am UTC](https://discourse.julialang.org/t/solve-time-is-not-working-jump/29062 "2019-10-03T08:01:47Z")

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I have updated Julia version to 1.0 and I have tried to find the new way to get the solve time reported by the solver, in my case Clp. I have tried to use the fonction solve\_time(model::Model) as described in documentat…

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## [Linear Algebra Rounding Errors?](https://discourse.julialang.org/t/linear-algebra-rounding-errors/29387)

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**Author:** [@manderson](https://discourse.julialang.org/u/manderson)\
**Replies:** 6\
**Last updated:** [October 3, 2019, 7:43am UTC](https://discourse.julialang.org/t/linear-algebra-rounding-errors/29387 "2019-10-03T07:43:04Z")

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I’ve run into some confusion about rounding with some linear algebra things which is causing some trouble for me in an image reconstruction algorithm I’m working on. When I run the following example code, I sometimes see…

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## [Fixing old code and ran into SetObjective error](https://discourse.julialang.org/t/fixing-old-code-and-ran-into-setobjective-error/29377)

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**Author:** [@ajimithing](https://discourse.julialang.org/u/ajimithing)\
**Replies:** 5\
**Last updated:** [October 3, 2019, 1:31am UTC](https://discourse.julialang.org/t/fixing-old-code-and-ran-into-setobjective-error/29377 "2019-10-03T01:31:01Z")

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I am working through an old code, and having to change a bunch of stuff to work with the new JuMP package. (ex. replacing {} with (), replacing @DefVar with variable, replacing AddConstraint with constraint, etc.) I’ve …

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## [Anonymous iterators?](https://discourse.julialang.org/t/anonymous-iterators/29426)

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**Author:** [@longemen3000](https://discourse.julialang.org/u/longemen3000)\
**Replies:** 4\
**Last updated:** [October 3, 2019, 12:30am UTC](https://discourse.julialang.org/t/anonymous-iterators/29426 "2019-10-03T00:30:06Z")

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i was reading in the Discourse Slack when someone asked about some syntax equivalent to the yield keyword in python. in Julia, the syntax ´for i in iter´ is lowered to iterate(iter::IterType) and iterate(iter::IterType,s…

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## [Problem installing IJulia: ZMQ Failed installation OSX Mojave](https://discourse.julialang.org/t/problem-installing-ijulia-zmq-failed-installation-osx-mojave/24494)

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**Author:** [@davidbp](https://discourse.julialang.org/u/davidbp)\
**Replies:** 15\
**Last updated:** [October 3, 2019, 12:24am UTC](https://discourse.julialang.org/t/problem-installing-ijulia-zmq-failed-installation-osx-mojave/24494 "2019-10-03T00:24:15Z")

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Hello guys, I am having some issues using jupyter notebooks in 1.1. I tried several “solutions” to the problem found in discourse but none of them worked so I ended up erasing my previous Julia installation and all the…

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## [Math In Plots.jl](https://discourse.julialang.org/t/math-in-plots-jl/14930)

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**Author:** [@iwelch](https://discourse.julialang.org/u/iwelch)\
**Replies:** 11\
**Last updated:** [October 3, 2019, 12:22am UTC](https://discourse.julialang.org/t/math-in-plots-jl/14930 "2019-10-03T00:22:52Z")

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could someone please show me how to set a simple equation into a plot, say \\sqrt{\\frac{a}{b}} ?

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## [Pairwise distances from a single column or vector](https://discourse.julialang.org/t/pairwise-distances-from-a-single-column-or-vector/29415)

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**Author:** [@jessecm](https://discourse.julialang.org/u/jessecm)\
**Replies:** 7\
**Last updated:** [October 2, 2019, 10:30pm UTC](https://discourse.julialang.org/t/pairwise-distances-from-a-single-column-or-vector/29415 "2019-10-02T22:30:05Z")

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I’m a new Julia user, so this might be really obvious, but is there a straight-forward way to generate a pairwise distance matrix from a single vector or column? In R, it’s pretty straightforward: for the vector c(2, 4…

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## [Custom updating binary operator](https://discourse.julialang.org/t/custom-updating-binary-operator/29301)

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**Author:** [@greg\_plowman](https://discourse.julialang.org/u/greg_plowman)\
**Replies:** 5\
**Last updated:** [October 2, 2019, 9:21pm UTC](https://discourse.julialang.org/t/custom-updating-binary-operator/29301 "2019-10-02T21:21:00Z")

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I have defined union for a custom set type. Base.union(a::MySet, b::MySet) = ... Then the following work as expected: union(a, b) a ∪ b Is it possible for the updating operator a ∪= b to have the expected interpretat…

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