# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1742

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

**Page:** 1743

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## [Mapping for within Artifacts.toml already exists](https://discourse.julialang.org/t/mapping-for-within-artifacts-toml-already-exists/39831)

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**Author:** [@yakir12](https://discourse.julialang.org/u/yakir12)\
**Replies:** 4\
**Last updated:** [May 20, 2020, 2:15pm UTC](https://discourse.julialang.org/t/mapping-for-within-artifacts-toml-already-exists/39831 "2020-05-20T14:15:13Z")

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I updated an artifact online and wanted therefore to remove the existing (old) artifact I had locally, so I went and found the folder that contained it (in .julia/artifacts/hash/here) and just deleted it. Now I get this …

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## [SMTPClient: Format mail body](https://discourse.julialang.org/t/smtpclient-format-mail-body/39818)

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**Author:** [@uwechsler](https://discourse.julialang.org/u/uwechsler)\
**Replies:** 2\
**Last updated:** [May 20, 2020, 12:57pm UTC](https://discourse.julialang.org/t/smtpclient-format-mail-body/39818 "2020-05-20T12:57:48Z")

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Is there a way to format the content of an email in SMTPClient.jl with HTML tags or in another way? For example by using this example but with additional \<b\> tags body = IOBuffer( "Date: Fri, 18 Oct 2013 21:44:29 +0…

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## [Problems updating/installing packages due to anti-virus](https://discourse.julialang.org/t/problems-updating-installing-packages-due-to-anti-virus/39760)

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**Author:** [@sbacelar](https://discourse.julialang.org/u/sbacelar)\
**Replies:** 5\
**Last updated:** [May 20, 2020, 12:55pm UTC](https://discourse.julialang.org/t/problems-updating-installing-packages-due-to-anti-virus/39760 "2020-05-20T12:55:29Z")

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I am using Kaspersky anti-virus on Windows 10 and I have been having some issues when I try to install or upgrade some packages in Julia. I am not totally sure about this but when I have problems I pause the anti-virus a…

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## [Julia v1.2.0 on Windows Server 2012 R2](https://discourse.julialang.org/t/julia-v1-2-0-on-windows-server-2012-r2/28277)

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**Author:** [@greg\_plowman](https://discourse.julialang.org/u/greg_plowman)\
**Replies:** 8\
**Last updated:** [May 20, 2020, 12:36pm UTC](https://discourse.julialang.org/t/julia-v1-2-0-on-windows-server-2012-r2/28277 "2020-05-20T12:36:14Z")

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I cannot start Julia v1.2.0 on Windows Server 2012 R2. The installation seems successful, but when starting Julia the terminal opens momentarily and then exits immediately. The problem occurs on multiple servers with s…

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## [@kwdef and parametric types](https://discourse.julialang.org/t/kwdef-and-parametric-types/39825)

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**Author:** [@hendri54](https://discourse.julialang.org/u/hendri54)\
**Replies:** 0\
**Last updated:** [May 20, 2020, 12:20pm UTC](https://discourse.julialang.org/t/kwdef-and-parametric-types/39825 "2020-05-20T12:20:24Z")

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I wonder why the following errors: julia\> Base.@kwdef mutable struct A1{F1} a :: F1 b :: F1 = zero(F1) end julia\> A1(a = 1.0) ERROR: UndefVarError: F1 not defined Stacktrace: \[1\] (::Core.v…

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## [Variable defined - for loop](https://discourse.julialang.org/t/variable-defined-for-loop/39813)

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**Author:** [@haankers](https://discourse.julialang.org/u/haankers)\
**Replies:** 1\
**Last updated:** [May 20, 2020, 11:34am UTC](https://discourse.julialang.org/t/variable-defined-for-loop/39813 "2020-05-20T11:34:50Z")

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I know there have been some questions here before on this same topic but I just wanted to note this undefined variable behaviour as strange. Just to clarify this code runs for case 1 and 2, but errors with an undefined v…

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## [Plotting streamlines](https://discourse.julialang.org/t/plotting-streamlines/39690)

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**Author:** [@Alireza\_Ghavaminia](https://discourse.julialang.org/u/Alireza_Ghavaminia)\
**Replies:** 4\
**Last updated:** [May 20, 2020, 11:27am UTC](https://discourse.julialang.org/t/plotting-streamlines/39690 "2020-05-20T11:27:49Z")

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Hello everyone, I have 2d vectors u and v which are velocity fields in x and y direction, How can I plot the streamlines?

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## [Importing a Python Module from another directory](https://discourse.julialang.org/t/importing-a-python-module-from-another-directory/28310)

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**Author:** [@marinarrd](https://discourse.julialang.org/u/marinarrd)\
**Replies:** 4\
**Last updated:** [May 20, 2020, 11:13am UTC](https://discourse.julialang.org/t/importing-a-python-module-from-another-directory/28310 "2020-05-20T11:13:31Z")

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I am very new to Julia. I would like to use python module from another directory. I have looked all over for instructions but none of them seem to work for me. Could someone please give me step by step instructions from …

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## [Julia-client package issue](https://discourse.julialang.org/t/julia-client-package-issue/39816)

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**Author:** [@Johncowk](https://discourse.julialang.org/u/Johncowk)\
**Replies:** 2\
**Last updated:** [May 20, 2020, 10:51am UTC](https://discourse.julialang.org/t/julia-client-package-issue/39816 "2020-05-20T10:51:35Z")

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I have a problem in atom, when I try to launch julia by pressing enter, julia exits immediately. I have seen on another post that the julia-client package might responsible for this issue and decided to re-install it. …

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## [Julia - Method Error](https://discourse.julialang.org/t/julia-method-error/39804)

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**Author:** [@Dishant-P](https://discourse.julialang.org/u/Dishant-P)\
**Replies:** 2\
**Last updated:** [May 20, 2020, 10:08am UTC](https://discourse.julialang.org/t/julia-method-error/39804 "2020-05-20T10:08:14Z")

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Even though I defined the method, the method is still not recognised. Following are the two functions defined. @resumable function iterate\_regions(self::Conv13, image) h, w = size(image) for i in 1:h-1 …

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## [Submodules: access of objects and documentation of modules](https://discourse.julialang.org/t/submodules-access-of-objects-and-documentation-of-modules/39753)

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**Author:** [@sylvaticus](https://discourse.julialang.org/u/sylvaticus)\
**Replies:** 1\
**Last updated:** [May 20, 2020, 7:48am UTC](https://discourse.julialang.org/t/submodules-access-of-objects-and-documentation-of-modules/39753 "2020-05-20T07:48:13Z")

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Let’s say I have a package with the following organisation (from @GunnarFarneback on post:2 of topic:21709): P.jl: module P include("C.jl") # shared utilities code include("M1.jl") include("M2.jl") end M1.jl: modu…

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## [Registering a package that depends on MATLAB.jl](https://discourse.julialang.org/t/registering-a-package-that-depends-on-matlab-jl/39755)

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**Author:** [@yakir12](https://discourse.julialang.org/u/yakir12)\
**Replies:** 5\
**Last updated:** [May 20, 2020, 7:30am UTC](https://discourse.julialang.org/t/registering-a-package-that-depends-on-matlab-jl/39755 "2020-05-20T07:30:42Z")

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I’m trying to register a package that depends on MATLAB.jl and I’m getting blocked by an error during CI: ERROR: LoadError: LoadError: InitError: failed process: Process(\`which matlab\`, ProcessExited(1)) \[1\] Which mak…

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## [Strange behavior when installing uber-juno extension](https://discourse.julialang.org/t/strange-behavior-when-installing-uber-juno-extension/39800)

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**Author:** [@pauljurczak](https://discourse.julialang.org/u/pauljurczak)\
**Replies:** 1\
**Last updated:** [May 20, 2020, 4:18am UTC](https://discourse.julialang.org/t/strange-behavior-when-installing-uber-juno-extension/39800 "2020-05-20T04:18:02Z")

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I just installed Atom v1.47.0 on Ubuntu 18.04 using atom-amd64.deb , launched it and selected uber-juno extension for installation. I’m facing a grayed-out window with a text input dialog and menu bar active. Was the …

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## [Type instability with StaticArrays.jl and "type alias"](https://discourse.julialang.org/t/type-instability-with-staticarrays-jl-and-type-alias/39763)

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**Author:** [@ranocha](https://discourse.julialang.org/u/ranocha)\
**Replies:** 6\
**Last updated:** [May 20, 2020, 4:03am UTC](https://discourse.julialang.org/t/type-instability-with-staticarrays-jl-and-type-alias/39763 "2020-05-20T04:03:33Z")

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I see the following type instability in current Julia v1.4 and master (commit cebd4fa959). julia\> using StaticArrays \[ Info: Precompiling StaticArrays \[90137ffa-7385-5640-81b9-e52037218182\] julia\> struct Foo{N} end ju…

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## [How to parallel Julia on multiple nodes on HPC (slurm)?](https://discourse.julialang.org/t/how-to-parallel-julia-on-multiple-nodes-on-hpc-slurm/39730)

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**Author:** [@zxjroger](https://discourse.julialang.org/u/zxjroger)\
**Replies:** 11\
**Last updated:** [May 20, 2020, 3:55am UTC](https://discourse.julialang.org/t/how-to-parallel-julia-on-multiple-nodes-on-hpc-slurm/39730 "2020-05-20T03:55:35Z")

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The parallel part of my Julia script utilizes the Distributed.jl package and the remotecall\_fetch function. (I am not using MPI.) In short, it calculates many linear programming problems in parallel independently. (Here …

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## [Love Julia, but..... Type hierarchy is frustrating](https://discourse.julialang.org/t/love-julia-but-type-hierarchy-is-frustrating/39651)

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**Author:** [@jfchessa](https://discourse.julialang.org/u/jfchessa)\
**Replies:** 21\
**Last updated:** [May 20, 2020, 3:04am UTC](https://discourse.julialang.org/t/love-julia-but-type-hierarchy-is-frustrating/39651 "2020-05-20T03:04:43Z")

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Two things that I have so much frustration with in Julia are importing and all the type and abstract type hierarchy. For example why does the following happen? But you need this to be robust to do multiple dispatch, …

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## [Passing arrays with unspecified type](https://discourse.julialang.org/t/passing-arrays-with-unspecified-type/39407)

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**Author:** [@iamsuddhasattwa](https://discourse.julialang.org/u/iamsuddhasattwa)\
**Replies:** 8\
**Last updated:** [May 20, 2020, 3:04am UTC](https://discourse.julialang.org/t/passing-arrays-with-unspecified-type/39407 "2020-05-20T03:04:36Z")

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This is a question about efficiency. Suppose I have a routine which performs an operation in the same manner on an array irrespective of whether the entries are Int, Float or Complex. The output type will be an array wit…

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## [\`\`\`@.\`\`\` throws unexpected error](https://discourse.julialang.org/t/throws-unexpected-error/39772)

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**Author:** [@Henri\_Laurie](https://discourse.julialang.org/u/Henri_Laurie)\
**Replies:** 5\
**Last updated:** [May 19, 2020, 9:58pm UTC](https://discourse.julialang.org/t/throws-unexpected-error/39772 "2020-05-19T21:58:31Z")

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I get a somewhat odd error with @. MWE: julia\> y = Array{Float64}(undef, 2, 2); @. y =rand(2,2) + ones(2,2) ERROR: MethodError: Cannot \`convert\` an object of type Array{Float64,2} to an object of type Float64 Where is …

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## [Slow compilation, i think, not sure how to debug](https://discourse.julialang.org/t/slow-compilation-i-think-not-sure-how-to-debug/39741)

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**Author:** [@purplishrock](https://discourse.julialang.org/u/purplishrock)\
**Replies:** 15\
**Last updated:** [May 20, 2020, 1:14am UTC](https://discourse.julialang.org/t/slow-compilation-i-think-not-sure-how-to-debug/39741 "2020-05-20T01:14:38Z")

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I have a very simple program, on the order of 50 lines, which uses CSV to read a 2 entry-per-line, 448 line CSV file. i have put @time on the using statements and they are normal (oh why oh why is PyPlot 8s ?!) total t…

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## [\[ANN\] JDF.jl v0.2.0 - Julia DataFrames serialization format](https://discourse.julialang.org/t/ann-jdf-jl-v0-2-0-julia-dataframes-serialization-format/30217)

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**Author:** [@xiaodai](https://discourse.julialang.org/u/xiaodai)\
**Replies:** 11\
**Last updated:** [May 19, 2020, 8:38pm UTC](https://discourse.julialang.org/t/ann-jdf-jl-v0-2-0-julia-dataframes-serialization-format/30217 "2020-05-19T20:38:14Z")

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JDF is the Julia DataFrames serialization format. It’s a specialised serialization format and hence doesn’t support arbitrary objects like JLD2 and JLSO. This loss of generality is more than made up for in gains in speed…

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## [Customize quantile in DataFrames Combine summary](https://discourse.julialang.org/t/customize-quantile-in-dataframes-combine-summary/39774)

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**Author:** [@Nelain](https://discourse.julialang.org/u/Nelain)\
**Replies:** 2\
**Last updated:** [May 19, 2020, 7:32pm UTC](https://discourse.julialang.org/t/customize-quantile-in-dataframes-combine-summary/39774 "2020-05-19T19:32:15Z")

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Hello, I am trying to summarize a GroupedDataFrame: df2 = CSV.read(raw"\_Q\\Test.csv"); gd = groupby(df2, :Age\_Catg) print( combine(gd, nrow ,:Income =\> mean ,:Income =\> middle ,:Income =\> …

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## [Fail to start Julia in Juno. \`execvp(3) failed\`](https://discourse.julialang.org/t/fail-to-start-julia-in-juno-execvp-3-failed/11336)

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**Author:** [@chobbes](https://discourse.julialang.org/u/chobbes)\
**Replies:** 16\
**Last updated:** [May 19, 2020, 7:02pm UTC](https://discourse.julialang.org/t/fail-to-start-julia-in-juno-execvp-3-failed/11336 "2020-05-19T19:02:00Z")

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Freshly installed JuliaPro. Failed to start Julia in REPL. Anyone can give me a hint? Press Enter to start a new session. Starting Julia... execvp(3) failed.: No such file or directory Julia has exited.

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## [Julia Crashes while Typing](https://discourse.julialang.org/t/julia-crashes-while-typing/39756)

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**Author:** [@J\_Bowman](https://discourse.julialang.org/u/J_Bowman)\
**Replies:** 2\
**Last updated:** [May 19, 2020, 6:34pm UTC](https://discourse.julialang.org/t/julia-crashes-while-typing/39756 "2020-05-19T18:34:11Z")

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I am using Julia 1.0.5 and Juno 0.3.0. My code seemingly runs fine, but after running, Julia will crash if I write anything else afterward, giving the following error message: Exception: EXCEPTION\_ACCESS\_VIOLATION at 0x…

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## [Unused \`where T\` causes a function to become very slow](https://discourse.julialang.org/t/unused-where-t-causes-a-function-to-become-very-slow/39727)

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**Author:** [@mabokhamis](https://discourse.julialang.org/u/mabokhamis)\
**Replies:** 12\
**Last updated:** [May 19, 2020, 5:07pm UTC](https://discourse.julialang.org/t/unused-where-t-causes-a-function-to-become-very-slow/39727 "2020-05-19T17:07:41Z")

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We noticed that an unused where T in a function declaration can cause the function to become much slower and to allocate a lot more memory. Consider for example the following two functions which are identical except that…

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## [Call for Mentors: MLH Fellowship + The Julia Language](https://discourse.julialang.org/t/call-for-mentors-mlh-fellowship-the-julia-language/39764)

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**Author:** [@logankilpatrick](https://discourse.julialang.org/u/logankilpatrick)\
**Replies:** 0\
**Last updated:** [May 19, 2020, 4:39pm UTC](https://discourse.julialang.org/t/call-for-mentors-mlh-fellowship-the-julia-language/39764 "2020-05-19T16:39:24Z")

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Hey all! The Julia Language was recently selected as an Open Source org to mentor students as part of the MLH Fellowship. You can read more about MLH and the Fellowship here. We are looking for mentors who are active i…

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## [Weird broadcasting behaviour](https://discourse.julialang.org/t/weird-broadcasting-behaviour/39762)

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**Author:** [@Henri\_Laurie](https://discourse.julialang.org/u/Henri_Laurie)\
**Replies:** 1\
**Last updated:** [May 19, 2020, 3:56pm UTC](https://discourse.julialang.org/t/weird-broadcasting-behaviour/39762 "2020-05-19T15:56:14Z")

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Broadcasting works for matrices up to 10 by 10, then fails: julia\> n=10; A = rand(n,n); B = ones(n,n); julia\> y .= A .+ B; julia\> n=11; A = rand(n,n); B = ones(n,n); julia\> y .= A .+ B; ERROR: DimensionMismatch("ar…

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## [Language impediments to inference of real-time streaming models](https://discourse.julialang.org/t/language-impediments-to-inference-of-real-time-streaming-models/39731)

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**Author:** [@marty0801](https://discourse.julialang.org/u/marty0801)\
**Replies:** 6\
**Last updated:** [May 19, 2020, 1:42pm UTC](https://discourse.julialang.org/t/language-impediments-to-inference-of-real-time-streaming-models/39731 "2020-05-19T13:42:15Z")

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I’m debating whether to attempt a Julia solution to a particular “streaming” inference problem in which a global data model is constantly being updated with new data. I’m new to the language, but there seems to be langua…

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## [Efficient representation and operations on symmetric zero-diagonal tensors](https://discourse.julialang.org/t/efficient-representation-and-operations-on-symmetric-zero-diagonal-tensors/39751)

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**Author:** [@hessammehr](https://discourse.julialang.org/u/hessammehr)\
**Replies:** 0\
**Last updated:** [May 19, 2020, 1:17pm UTC](https://discourse.julialang.org/t/efficient-representation-and-operations-on-symmetric-zero-diagonal-tensors/39751 "2020-05-19T13:17:56Z")

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I am looking for an efficient way of representing symmetric tensors with all zero diagonals (any combination of two indices, that is). Since these tensors are going to be fairly small, a fair number of entries are going …

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## [Include git-tree-sha1 and giturl for registries in Manifest.toml?](https://discourse.julialang.org/t/include-git-tree-sha1-and-giturl-for-registries-in-manifest-toml/39696)

<div class="topic-metadata">

**Author:** [@schlichtanders](https://discourse.julialang.org/u/schlichtanders)\
**Replies:** 1\
**Last updated:** [May 19, 2020, 8:27am UTC](https://discourse.julialang.org/t/include-git-tree-sha1-and-giturl-for-registries-in-manifest-toml/39696 "2020-05-19T08:27:38Z")

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just stumbled upon creating an old example from a Manifest file. It does not instantiate… because packages are no longer available from the registry (for my case it is DiffBase, but that does not matter). It seems apt …

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## [\`x - y\` is not \`x + (-y)\`?](https://discourse.julialang.org/t/x-y-is-not-x-y/39726)

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**Author:** [@heliosdrm](https://discourse.julialang.org/u/heliosdrm)\
**Replies:** 2\
**Last updated:** [May 19, 2020, 7:29am UTC](https://discourse.julialang.org/t/x-y-is-not-x-y/39726 "2020-05-19T07:29:18Z")

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In some places I have found that in computer algebra, x - y can be defined as x + (-y). E.g. in Cohen’s Computer Algebra and Symbolic Computation: Mathematical Methods (page 51) However this is not a rule for Julia type…

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