# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1771

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

**Page:** 1772

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## [Constant-time arithmetic operations](https://discourse.julialang.org/t/constant-time-arithmetic-operations/37738)

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**Author:** [@fjarri](https://discourse.julialang.org/u/fjarri)\
**Replies:** 15\
**Last updated:** [April 19, 2020, 5:48am UTC](https://discourse.julialang.org/t/constant-time-arithmetic-operations/37738 "2020-04-19T05:48:26Z")

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Julia has a great potential as a language for cryptographic implementations, the niche Rust is now beginning to occupy. There is one big obstacle for that: uncertainty about constant-time guarantees of operations. Rust i…

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## [\[Call to Arms\] The Quest to Label every Julia Package](https://discourse.julialang.org/t/call-to-arms-the-quest-to-label-every-julia-package/37817)

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**Author:** [@djsegal](https://discourse.julialang.org/u/djsegal)\
**Replies:** 8\
**Last updated:** [April 19, 2020, 2:51am UTC](https://discourse.julialang.org/t/call-to-arms-the-quest-to-label-every-julia-package/37817 "2020-04-19T02:51:27Z")

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Hi All, This is an open request to help out the community by categorizing Julia packages. Working on the structure of Svaksha’s curated list, I believe we could label a couple hundred registered packages! The way you c…

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## [A question about array](https://discourse.julialang.org/t/a-question-about-array/37828)

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**Author:** [@abcde](https://discourse.julialang.org/u/abcde)\
**Replies:** 1\
**Last updated:** [April 19, 2020, 2:32am UTC](https://discourse.julialang.org/t/a-question-about-array/37828 "2020-04-19T02:32:04Z")

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a=\[7 -1 -1\] b=union(a) c=reshape(b,(:,3)) print(c) this is a simple code,but it is wrong,it shows: DimensionMismatch(“array size 2 must be divisible by the product of the new dimensions (Colon(), 3)”) why?thank you!

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## [Precompile errors on Ubuntu 18.04 LTS (AWS)](https://discourse.julialang.org/t/precompile-errors-on-ubuntu-18-04-lts-aws/37205)

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**Author:** [@mpf01](https://discourse.julialang.org/u/mpf01)\
**Replies:** 4\
**Last updated:** [April 19, 2020, 1:41am UTC](https://discourse.julialang.org/t/precompile-errors-on-ubuntu-18-04-lts-aws/37205 "2020-04-19T01:41:29Z")

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I installed the Generic x86 Linux Julia 1.4.0 binary from here, onto an Ubuntu instance on AWS. Julia works fine at the REPL, but some packages cause errors during precompilation. For example, Julia\> using Distributions…

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## [Problem about \`quote\` in macro definition](https://discourse.julialang.org/t/problem-about-quote-in-macro-definition/37806)

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**Author:** [@KDr2](https://discourse.julialang.org/u/KDr2)\
**Replies:** 4\
**Last updated:** [April 19, 2020, 1:31am UTC](https://discourse.julialang.org/t/problem-about-quote-in-macro-definition/37806 "2020-04-19T01:31:17Z")

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I wrote the code below: module T function f1 end macro m1(sym) :(f1(::typeof($(esc(sym)))) = 1) end macro m2(sym) quote f1(::typeof($(esc(sym)))) = 1 end end macro m3(sym) quote $(es…

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## [How to export a column vector to text file with writedlm function](https://discourse.julialang.org/t/how-to-export-a-column-vector-to-text-file-with-writedlm-function/37818)

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**Author:** [@fhkm](https://discourse.julialang.org/u/fhkm)\
**Replies:** 8\
**Last updated:** [April 19, 2020, 1:21am UTC](https://discourse.julialang.org/t/how-to-export-a-column-vector-to-text-file-with-writedlm-function/37818 "2020-04-19T01:21:42Z")

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I want to export a column vector to text file. using DelimitedFiles y=\[1;2;3.4;5.5;7;8;45.78;0.445;76\]; io=open(“x1.txt”,“w”) do io writedlm(io,y) end After the codes is run, I did not get the result I expect. Se…

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## [Plot contours of a heatmap](https://discourse.julialang.org/t/plot-contours-of-a-heatmap/37804)

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**Author:** [@HenriDeh](https://discourse.julialang.org/u/HenriDeh)\
**Replies:** 3\
**Last updated:** [April 18, 2020, 11:30pm UTC](https://discourse.julialang.org/t/plot-contours-of-a-heatmap/37804 "2020-04-18T23:30:24Z")

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I have this heatmap of a matrix with Integer values. But it is best suited for continuous values, so I tried contour instead but the contour links the center of the squares like this: Is there an easy way to trac…

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## [Help to improve performance of gradient calculation on tensor operations](https://discourse.julialang.org/t/help-to-improve-performance-of-gradient-calculation-on-tensor-operations/37773)

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**Author:** [@sjrodahl](https://discourse.julialang.org/u/sjrodahl)\
**Replies:** 3\
**Last updated:** [April 18, 2020, 8:14pm UTC](https://discourse.julialang.org/t/help-to-improve-performance-of-gradient-calculation-on-tensor-operations/37773 "2020-04-18T20:14:18Z")

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I need help improving the performance of gradient calculation of a piece of my program, and understanding why it is performing as it does. As part of a larger machine learning system, I need a pairwise similarity measur…

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## [What is the right usage of where clauses to avoid these function calls?](https://discourse.julialang.org/t/what-is-the-right-usage-of-where-clauses-to-avoid-these-function-calls/37812)

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**Author:** [@pdubya](https://discourse.julialang.org/u/pdubya)\
**Replies:** 2\
**Last updated:** [April 18, 2020, 8:39pm UTC](https://discourse.julialang.org/t/what-is-the-right-usage-of-where-clauses-to-avoid-these-function-calls/37812 "2020-04-18T20:39:36Z")

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Hi all, Trying to write a function to extract one of the type parameters from the instance of a struct. Have it working but wondering what the syntax would be to this in one line as opposed to using the Type{…} functio…

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## [Building Julia with Intel MKL and Intel LIBM on macOS](https://discourse.julialang.org/t/building-julia-with-intel-mkl-and-intel-libm-on-macos/37796)

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**Author:** [@carstenbauer](https://discourse.julialang.org/u/carstenbauer)\
**Replies:** 6\
**Last updated:** [April 18, 2020, 5:12pm UTC](https://discourse.julialang.org/t/building-julia-with-intel-mkl-and-intel-libm-on-macos/37796 "2020-04-18T17:12:01Z")

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Hi all, Where do I find good instructions on how to compile Julia (1.4.0) with Intel MKL and Intel LIBM on macOS (Catalina 10.15.4)? Unfortunately, the “guide” here doesn’t work for me. After installing the Intel Paral…

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## [MySQL.jl Not Installing](https://discourse.julialang.org/t/mysql-jl-not-installing/37622)

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**Author:** [@dburch](https://discourse.julialang.org/u/dburch)\
**Replies:** 3\
**Last updated:** [April 18, 2020, 4:42pm UTC](https://discourse.julialang.org/t/mysql-jl-not-installing/37622 "2020-04-18T16:42:11Z")

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I am not able to install the MySQL.jl package. I am using Julia version 1.0.5. Here is the error: (v1.0) pkg\> add MySQL Resolving package versions... ERROR: Error when installing package LibSSH2\_jll: HTTP.ExceptionRequ…

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## [Saving workspace in JLD](https://discourse.julialang.org/t/saving-workspace-in-jld/31051)

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**Author:** [@tanya](https://discourse.julialang.org/u/tanya)\
**Replies:** 2\
**Last updated:** [April 18, 2020, 2:32pm UTC](https://discourse.julialang.org/t/saving-workspace-in-jld/31051 "2020-04-18T14:32:33Z")

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I have a number of saved \*.jld files from Julia 0.6.4 but had to switch to Julia 1.2 recently. With JLD package @load seems work fine, but there is a problem with @save(“workspace.jld”). It complains about current module…

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## [JDBC 2 Concurrent Connections](https://discourse.julialang.org/t/jdbc-2-concurrent-connections/37608)

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**Author:** [@dburch](https://discourse.julialang.org/u/dburch)\
**Replies:** 1\
**Last updated:** [April 18, 2020, 1:04pm UTC](https://discourse.julialang.org/t/jdbc-2-concurrent-connections/37608 "2020-04-18T13:04:22Z")

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I am able to use JDBC to connect to an Oracle DB or a MySQL DB. It works great. Now I am trying to connect to both databases at the same time. How do I do that? Can I use two different drivers at the same time? Here’s a…

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## [BoundsError: attempt to access n-element UnitRange{Int32} at index \[n+1\]](https://discourse.julialang.org/t/boundserror-attempt-to-access-n-element-unitrange-int32-at-index-n-1/37508)

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**Author:** [@jackjacker](https://discourse.julialang.org/u/jackjacker)\
**Replies:** 1\
**Last updated:** [April 18, 2020, 10:32am UTC](https://discourse.julialang.org/t/boundserror-attempt-to-access-n-element-unitrange-int32-at-index-n-1/37508 "2020-04-18T10:32:27Z")

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Hello, I’m recently using Knet and working on a CNN. I have a dataset-input of 20000x1x1x200000 which I use for training As soon as i start training with progress!(sgd(dtrn,ncycle(n))), I get following the error: Bou…

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## [Annotation which doesn't depend on the scale?](https://discourse.julialang.org/t/annotation-which-doesnt-depend-on-the-scale/37759)

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**Author:** [@br500](https://discourse.julialang.org/u/br500)\
**Replies:** 3\
**Last updated:** [April 18, 2020, 8:29am UTC](https://discourse.julialang.org/t/annotation-which-doesnt-depend-on-the-scale/37759 "2020-04-18T08:29:30Z")

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Is there any way to add annotation (which doesn’t depend on the scale) to plot? I’ve seen: plot!(annotation = (0, 1, text(“example”))) but i want to “stick” annotation for example 15mm from left border, 15 mm from t…

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## [Implementing sum](https://discourse.julialang.org/t/implementing-sum/37789)

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**Author:** [@Nimpa](https://discourse.julialang.org/u/Nimpa)\
**Replies:** 11\
**Last updated:** [April 18, 2020, 8:14am UTC](https://discourse.julialang.org/t/implementing-sum/37789 "2020-04-18T08:14:57Z")

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how can i implement this summation using reduce,sum,mapreduce, array comprehension and generators

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## [JuliaPro JDBC.destroy() not working](https://discourse.julialang.org/t/juliapro-jdbc-destroy-not-working/37645)

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**Author:** [@dburch](https://discourse.julialang.org/u/dburch)\
**Replies:** 4\
**Last updated:** [April 18, 2020, 4:19am UTC](https://discourse.julialang.org/t/juliapro-jdbc-destroy-not-working/37645 "2020-04-18T04:19:30Z")

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I am trying to use JDBC in the JuliaPro IDE, but it doesn’t seem to release the JMV from memory when the destroy() method is called. If I run the following code twice, then I get an error, but shouldn’t it work if destro…

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## [Segmentation fault in garbage collector](https://discourse.julialang.org/t/segmentation-fault-in-garbage-collector/37673)

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**Author:** [@brianguenter](https://discourse.julialang.org/u/brianguenter)\
**Replies:** 12\
**Last updated:** [April 18, 2020, 3:58am UTC](https://discourse.julialang.org/t/segmentation-fault-in-garbage-collector/37673 "2020-04-18T03:58:53Z")

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This doesn’t seem like the right place to post this error but none of the other topic areas seemed quite right either. If this is the wrong place please let me know where this should go. A segmentation fault is occurrin…

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## [MKL and libm compile notes: macOS](https://discourse.julialang.org/t/mkl-and-libm-compile-notes-macos/21024)

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**Author:** [@Egwene\_al\_Vere](https://discourse.julialang.org/u/Egwene_al_Vere)\
**Replies:** 6\
**Last updated:** [April 18, 2020, 12:24am UTC](https://discourse.julialang.org/t/mkl-and-libm-compile-notes-macos/21024 "2020-04-18T00:24:58Z")

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Just compiled julia with mkl and libm on macOS, ran some tests and it looks to be working fine. It took a while and the info I found online are in various places (mainly from this github issue and the the intel documenta…

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## [Plot padding when \`showaxis\` false](https://discourse.julialang.org/t/plot-padding-when-showaxis-false/37716)

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**Author:** [@chriswaudby](https://discourse.julialang.org/u/chriswaudby)\
**Replies:** 2\
**Last updated:** [April 18, 2020, 12:01am UTC](https://discourse.julialang.org/t/plot-padding-when-showaxis-false/37716 "2020-04-18T00:01:58Z")

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I would like to make some plots where the y axis is not shown. I can do this by setting yshowaxis=false, but there is then ugly excess padding on the left of the figure. For example: using Plots y=\[1,1000000\] plot(y,ys…

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## [Memory allocation for sparse matrix multiplication](https://discourse.julialang.org/t/memory-allocation-for-sparse-matrix-multiplication/37787)

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**Author:** [@volkerkarle](https://discourse.julialang.org/u/volkerkarle)\
**Replies:** 1\
**Last updated:** [April 17, 2020, 11:00pm UTC](https://discourse.julialang.org/t/memory-allocation-for-sparse-matrix-multiplication/37787 "2020-04-17T23:00:33Z")

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Dear folks, This is my first post, so feel free to relocate me to an appropriate tag/ group/ domain, etc. etc. So I have the following questions: 1) How can I estimate the amount of memory needed for the multiplication…

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## [Adding packages not available through Pkg.add](https://discourse.julialang.org/t/adding-packages-not-available-through-pkg-add/37792)

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**Author:** [@iamsuddhasattwa](https://discourse.julialang.org/u/iamsuddhasattwa)\
**Replies:** 1\
**Last updated:** [April 17, 2020, 11:04pm UTC](https://discourse.julialang.org/t/adding-packages-not-available-through-pkg-add/37792 "2020-04-17T23:04:06Z")

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I wish to add a package called FastConv which I found on github. However, trying to add it the usual way using Pkg does not work. julia\> Pkg.add("FastConv"); ERROR: The following package names could not be resolved: \* …

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## [Libmbedtls not defined in julia 1.4.1 on ARM (Raspberry Pi)](https://discourse.julialang.org/t/libmbedtls-not-defined-in-julia-1-4-1-on-arm-raspberry-pi/37778)

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**Author:** [@Alexander-Barth](https://discourse.julialang.org/u/Alexander-Barth)\
**Replies:** 4\
**Last updated:** [April 17, 2020, 10:58pm UTC](https://discourse.julialang.org/t/libmbedtls-not-defined-in-julia-1-4-1-on-arm-raspberry-pi/37778 "2020-04-17T22:58:01Z")

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I try to install HTTP (requiring MbedTLS) on a Raspberry Pi 3 in julia 1.4.1 (official binaries). The armv7l platform should be supported as far as I can see (Releases · JuliaBinaryWrappers/MbedTLS\_jll.jl · GitHub ), bu…

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## [Strange inference problems here](https://discourse.julialang.org/t/strange-inference-problems-here/37734)

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**Author:** [@anon94023334](https://discourse.julialang.org/u/anon94023334)\
**Replies:** 7\
**Last updated:** [April 17, 2020, 10:20pm UTC](https://discourse.julialang.org/t/strange-inference-problems-here/37734 "2020-04-17T22:20:19Z")

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I’m seeing some weird behavior with respect to type inference. Here’s the code: function SimpleGraph{T}(nv::Integer, ne::Integer; rng::AbstractRNG=GLOBAL\_RNG) where {T\<:Integer} tnv = T(nv) maxe = div(Int(nv) \* …

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## [Nested dictionary usage](https://discourse.julialang.org/t/nested-dictionary-usage/37589)

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**Author:** [@CH-8](https://discourse.julialang.org/u/CH-8)\
**Replies:** 4\
**Last updated:** [April 17, 2020, 9:55pm UTC](https://discourse.julialang.org/t/nested-dictionary-usage/37589 "2020-04-17T21:55:11Z")

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Hi, I am trying to create a nested dictionary where integer tuple keys map to another dictionary with an integer key and a float value. When I try to add values to this data structure, I get a key error Test = Dict{Tu…

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## [TAPL in Julia](https://discourse.julialang.org/t/tapl-in-julia/37588)

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**Author:** [@adhalanay](https://discourse.julialang.org/u/adhalanay)\
**Replies:** 2\
**Last updated:** [April 17, 2020, 9:28pm UTC](https://discourse.julialang.org/t/tapl-in-julia/37588 "2020-04-17T21:28:47Z")

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Hello! I am reading the book “Types and Programming Languages” by B.Pierce and I’m trying to implement the various models in Julia. The code I am trying to translate is the following (in Ocaml): type term = TmTrue …

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## [Type parameters which depend on other type parameters](https://discourse.julialang.org/t/type-parameters-which-depend-on-other-type-parameters/37769)

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**Author:** [@jlchan](https://discourse.julialang.org/u/jlchan)\
**Replies:** 4\
**Last updated:** [April 17, 2020, 5:45pm UTC](https://discourse.julialang.org/t/type-parameters-which-depend-on-other-type-parameters/37769 "2020-04-17T17:45:18Z")

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Is there a way to specify a type parameter in a way that depends on another type parameter? For example, a StaticMatrix takes in types {M,N,T,L}, where M,N are dimensions and L is the length of the array. Is there a way…

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## [Badge url gives 404 for new package](https://discourse.julialang.org/t/badge-url-gives-404-for-new-package/37763)

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**Author:** [@ctkelley](https://discourse.julialang.org/u/ctkelley)\
**Replies:** 6\
**Last updated:** [April 17, 2020, 5:23pm UTC](https://discourse.julialang.org/t/badge-url-gives-404-for-new-package/37763 "2020-04-17T17:23:07Z")

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I am using Documenter for the second time. On the first package everything went fine. This time I got as far as populating the gh-pages branch correctly, but when I install the badge in README.md the link returns a 404. …

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## [Help registering a package with external/unregistered dependencies](https://discourse.julialang.org/t/help-registering-a-package-with-external-unregistered-dependencies/37745)

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**Author:** [@Iulian.Cioarca](https://discourse.julialang.org/u/Iulian.Cioarca)\
**Replies:** 2\
**Last updated:** [April 17, 2020, 5:14pm UTC](https://discourse.julialang.org/t/help-registering-a-package-with-external-unregistered-dependencies/37745 "2020-04-17T17:14:18Z")

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I wanted to register GitHub - iuliancioarca/GenericInstruments.jl: Bundles similar functionalities of instruments under a single generic object: power supplies, arbitrary waveform generators, etc. and I encountered a few…

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## [How can i pipe arbitrary strings into a temporary file pipe for programs that read from a file?](https://discourse.julialang.org/t/how-can-i-pipe-arbitrary-strings-into-a-temporary-file-pipe-for-programs-that-read-from-a-file/37695)

<div class="topic-metadata">

**Author:** [@NHDaly](https://discourse.julialang.org/u/NHDaly)\
**Replies:** 3\
**Last updated:** [April 17, 2020, 4:55pm UTC](https://discourse.julialang.org/t/how-can-i-pipe-arbitrary-strings-into-a-temporary-file-pipe-for-programs-that-read-from-a-file/37695 "2020-04-17T16:55:20Z")

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What is the julia pipeline equivalent to bash’s process substitution? https://unix.stackexchange.com/a/64011/43398 And/or can we use Pipe() to make a Named Pipe? https://unix.stackexchange.com/questions/63923/pseudo-f…

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