# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1897

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

**Page:** 1898

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## [Julia on Holochain](https://discourse.julialang.org/t/julia-on-holochain/30020)

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**Author:** [@Tim\_Sandgren](https://discourse.julialang.org/u/Tim_Sandgren)\
**Replies:** 10\
**Last updated:** [October 22, 2019, 8:03pm UTC](https://discourse.julialang.org/t/julia-on-holochain/30020 "2019-10-22T20:03:00Z")

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Holochain is an open source initiative to create a cloud infrastructure. Some time ago I pre-ordered a small computer that will be delivered when the system is ready. I ordered the product here: Holo is claiming tha…

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## [JuliaCloud for Azure?](https://discourse.julialang.org/t/juliacloud-for-azure/30182)

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**Author:** [@stvpwrs](https://discourse.julialang.org/u/stvpwrs)\
**Replies:** 0\
**Last updated:** [October 22, 2019, 6:46pm UTC](https://discourse.julialang.org/t/juliacloud-for-azure/30182 "2019-10-22T18:46:29Z")

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Hello, I am interested in contributing to a Julia project and was wondering if there are any efforts like JuliaCloud AWS for Azure? Steve

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## [Making mapslices drop dimensions for scalars results automatially](https://discourse.julialang.org/t/making-mapslices-drop-dimensions-for-scalars-results-automatially/19624)

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**Author:** [@Tamas\_Papp](https://discourse.julialang.org/u/Tamas_Papp)\
**Replies:** 3\
**Last updated:** [October 22, 2019, 6:42pm UTC](https://discourse.julialang.org/t/making-mapslices-drop-dimensions-for-scalars-results-automatially/19624 "2019-10-22T18:42:25Z")

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In a sense, I am looking for a workaround for #16606: for functions which return an array, I would like to keep it as is, but for functions which return a scalar, I would like to drop the relevant dimension. I can’t just…

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## [Properly query methods of a function?](https://discourse.julialang.org/t/properly-query-methods-of-a-function/30178)

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**Author:** [@Qiyamah](https://discourse.julialang.org/u/Qiyamah)\
**Replies:** 3\
**Last updated:** [October 22, 2019, 6:18pm UTC](https://discourse.julialang.org/t/properly-query-methods-of-a-function/30178 "2019-10-22T18:18:56Z")

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sig\_params(t::UnionAll) = sig\_params(t.body) sig\_params(t::DataType) = t.parameters\[2:end\] abstract type AT2{T\<:Real} end f(x::AT2{Float64}) = "AT2{Float64}" f(x::T) where T\<:AT2 = "T\<:AT2" julia\>…

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## [Is it possible to express a type relationship between arrays with different numbers of dimensions?](https://discourse.julialang.org/t/is-it-possible-to-express-a-type-relationship-between-arrays-with-different-numbers-of-dimensions/30149)

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**Author:** [@bcmichael](https://discourse.julialang.org/u/bcmichael)\
**Replies:** 21\
**Last updated:** [October 22, 2019, 5:12pm UTC](https://discourse.julialang.org/t/is-it-possible-to-express-a-type-relationship-between-arrays-with-different-numbers-of-dimensions/30149 "2019-10-22T17:12:12Z")

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What I really want to be able to do is express a type such as: struct Foo{T,N} a::Array{T,N} b::Array{T,N+1} # doesn't work but I hope it conveys what I want end The important part for me is that the b field has one mo…

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## [Documentation for parallel computing - clarification](https://discourse.julialang.org/t/documentation-for-parallel-computing-clarification/30057)

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**Author:** [@BioTurboNick](https://discourse.julialang.org/u/BioTurboNick)\
**Replies:** 3\
**Last updated:** [October 22, 2019, 4:43pm UTC](https://discourse.julialang.org/t/documentation-for-parallel-computing-clarification/30057 "2019-10-22T16:43:07Z")

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Two bits of clarification. Are these two statements correct? All parallel functions require that the user has started worker processes separately with addprocs(). You need to add at least 2 worker processes to see …

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## [Polyhedra no longer supported?](https://discourse.julialang.org/t/polyhedra-no-longer-supported/30179)

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**Author:** [@squirrel](https://discourse.julialang.org/u/squirrel)\
**Replies:** 1\
**Last updated:** [October 22, 2019, 4:34pm UTC](https://discourse.julialang.org/t/polyhedra-no-longer-supported/30179 "2019-10-22T16:34:05Z")

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Hi. I have Julia v1.2.0 running with Atom v1.40.1. I want to do some Fourier-Motzkin elimination, and I found the CDDLip.jl, and the Polyhedra.jl interface. The Polyhedra documentation says “Polyhedra supports Julia v0.…

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## [Problem construction advice in JuMP for speed](https://discourse.julialang.org/t/problem-construction-advice-in-jump-for-speed/30148)

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**Author:** [@bhalonen](https://discourse.julialang.org/u/bhalonen)\
**Replies:** 4\
**Last updated:** [October 22, 2019, 3:50pm UTC](https://discourse.julialang.org/t/problem-construction-advice-in-jump-for-speed/30148 "2019-10-22T15:50:07Z")

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I know that parallelization of problem construction has been advised against, so I am curious on what advice there is. Problem construction takes a significant amount of time on my problem, and is time significant operat…

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## [Editing UnionAll and putting it back together](https://discourse.julialang.org/t/editing-unionall-and-putting-it-back-together/30116)

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**Author:** [@Qiyamah](https://discourse.julialang.org/u/Qiyamah)\
**Replies:** 4\
**Last updated:** [October 22, 2019, 3:37pm UTC](https://discourse.julialang.org/t/editing-unionall-and-putting-it-back-together/30116 "2019-10-22T15:37:38Z")

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typ = Tuple{Int,T} where T\<:Real unwtyp = Base.unwrap\_unionall(typ) # Tuple{Int,T\<:Real} edited = edit(unwtyp,Real,Float64) # Tuple{Int,T\<:Float64}, has free type variables. I want to put Tuple{Int,T\<:Float64} back to …

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## [Type-stable zip of tuple](https://discourse.julialang.org/t/type-stable-zip-of-tuple/30105)

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**Author:** [@Tamas\_Papp](https://discourse.julialang.org/u/Tamas_Papp)\
**Replies:** 3\
**Last updated:** [October 22, 2019, 2:53pm UTC](https://discourse.julialang.org/t/type-stable-zip-of-tuple/30105 "2019-10-22T14:53:41Z")

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I have trouble getting this to infer (on 1.3; but the same happens on 1.2): function zipped\_pairs\_product(pairs) itrs = map(pair -\> zip(pair...), pairs) vec(collect(Iterators.product(itrs...))) end pairs = (1:5…

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## [Map/pmap and scalar argument](https://discourse.julialang.org/t/map-pmap-and-scalar-argument/30089)

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**Author:** [@BioTurboNick](https://discourse.julialang.org/u/BioTurboNick)\
**Replies:** 4\
**Last updated:** [October 22, 2019, 2:30pm UTC](https://discourse.julialang.org/t/map-pmap-and-scalar-argument/30089 "2019-10-22T14:30:31Z")

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Take this code: function foo(arg1, arg2, arg3) arg1 + arg2 + arg3 end map(foo, \[1;2;3\], \[4;5;6\], 5) This code is equivalent to \[foo(1, 4, 5)\], the other values discarded. Is this behavior desired for any reason? I…

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## [BigFloat memory usage](https://discourse.julialang.org/t/bigfloat-memory-usage/30136)

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**Author:** [@ckoe-bccms](https://discourse.julialang.org/u/ckoe-bccms)\
**Replies:** 1\
**Last updated:** [October 22, 2019, 2:20pm UTC](https://discourse.julialang.org/t/bigfloat-memory-usage/30136 "2019-10-22T14:20:11Z")

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Hello, I have a problem concerning the memory usage of BigFloats. I have quite some trouble switching a self-written ODE solver as well as DifferentialEquations.jl (less tests with that) from Float64 to BigFloat becaus…

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## [Why Rebugger.keybinding use this strange strings (anti-human)?](https://discourse.julialang.org/t/why-rebugger-keybinding-use-this-strange-strings-anti-human/29485)

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**Author:** [@bsnyh](https://discourse.julialang.org/u/bsnyh)\
**Replies:** 5\
**Last updated:** [October 22, 2019, 2:16pm UTC](https://discourse.julialang.org/t/why-rebugger-keybinding-use-this-strange-strings-anti-human/29485 "2019-10-22T14:16:46Z")

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Hi, I was trying to configure the keymap functions of Rebugger. Following is the code I put in the file startup.jl # This file should contain site-specific commands to be executed on Julia startup; # Users may store the…

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## [Trying to get pyplot backend to Plots, but end up with GKS plots anyway](https://discourse.julialang.org/t/trying-to-get-pyplot-backend-to-plots-but-end-up-with-gks-plots-anyway/22038)

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**Author:** [@NeonNeon](https://discourse.julialang.org/u/NeonNeon)\
**Replies:** 2\
**Last updated:** [October 22, 2019, 10:53am UTC](https://discourse.julialang.org/t/trying-to-get-pyplot-backend-to-plots-but-end-up-with-gks-plots-anyway/22038 "2019-10-22T10:53:27Z")

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I have several problems using the Plots package together with the PyPlot backend. My exmple looks like this, I have two packages MyPlot and MyFront. In MyPlot’s environment I have added Plots and PyPlot as dependencies…

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## [How to step to the next line using option n of Debugger.jl julia?](https://discourse.julialang.org/t/how-to-step-to-the-next-line-using-option-n-of-debugger-jl-julia/29483)

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**Author:** [@bsnyh](https://discourse.julialang.org/u/bsnyh)\
**Replies:** 26\
**Last updated:** [October 22, 2019, 7:54am UTC](https://discourse.julialang.org/t/how-to-step-to-the-next-line-using-option-n-of-debugger-jl-julia/29483 "2019-10-22T07:54:37Z")

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This should be simple, yet I need some lights. \_/ |\\\_\_'\_|\_|\_|\\\_\_'\_| | Official https://julialang.org/ release |\_\_/ | julia\> using Debugger \[ Info: Precompiling Debugger \[31a5f54b-26ea-5ae9-a837-f05…

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## [Libdl.dlopen can't find dependencies on workers while loading a shared library even though ldd detects the correct paths](https://discourse.julialang.org/t/libdl-dlopen-cant-find-dependencies-on-workers-while-loading-a-shared-library-even-though-ldd-detects-the-correct-paths/30156)

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**Author:** [@jishnub](https://discourse.julialang.org/u/jishnub)\
**Replies:** 0\
**Last updated:** [October 22, 2019, 6:40am UTC](https://discourse.julialang.org/t/libdl-dlopen-cant-find-dependencies-on-workers-while-loading-a-shared-library-even-though-ldd-detects-the-correct-paths/30156 "2019-10-22T06:40:19Z")

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I’m trying to call a fortran code that depends on lapack, blas, fftw3 etc that is compiled so a “.so” file on Linux. I am trying to run it on a SLURM cluster after submitting a job interactively. I can load the on a sing…

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## [Create lead and lag variable in DataFrame](https://discourse.julialang.org/t/create-lead-and-lag-variable-in-dataframe/8658)

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**Author:** [@Yifan\_Liu](https://discourse.julialang.org/u/Yifan_Liu)\
**Replies:** 14\
**Last updated:** [October 22, 2019, 5:05am UTC](https://discourse.julialang.org/t/create-lead-and-lag-variable-in-dataframe/8658 "2019-10-22T05:05:39Z")

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I am trying to create a lag and lead variable in DataFrame, in R and Python this can be easily done with lag, lead, and shift function, but I still could not get it done in Julia. My code is like this (does not work): …

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## [StackOverflow Error with Shootout function in DiffEqDevTools](https://discourse.julialang.org/t/stackoverflow-error-with-shootout-function-in-diffeqdevtools/30114)

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**Author:** [@Nirvik](https://discourse.julialang.org/u/Nirvik)\
**Replies:** 4\
**Last updated:** [October 21, 2019, 11:49pm UTC](https://discourse.julialang.org/t/stackoverflow-error-with-shootout-function-in-diffeqdevtools/30114 "2019-10-21T23:49:21Z")

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Hi, I am using Julia in Juno IDE. I keep getting a stack overflow error while trying to use the Shootout function in ODEdevTools package. Here is a screenshot of the stack trace: Please help.

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## [Making views the default indexing behavior in 2.0?](https://discourse.julialang.org/t/making-views-the-default-indexing-behavior-in-2-0/29954)

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**Author:** [@Oscar\_Smith](https://discourse.julialang.org/u/Oscar_Smith)\
**Replies:** 11\
**Last updated:** [October 21, 2019, 11:09pm UTC](https://discourse.julialang.org/t/making-views-the-default-indexing-behavior-in-2-0/29954 "2019-10-21T23:09:21Z")

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What would people think about making view default indexing behavior in 2.0? It would be a pretty big change, but given how as of 1.4 views allegedly might be non-allocating, it might make sense.

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## [Question about using the name "flux" in package name](https://discourse.julialang.org/t/question-about-using-the-name-flux-in-package-name/30060)

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**Author:** [@DrChainsaw](https://discourse.julialang.org/u/DrChainsaw)\
**Replies:** 3\
**Last updated:** [October 21, 2019, 10:27pm UTC](https://discourse.julialang.org/t/question-about-using-the-name-flux-in-package-name/30060 "2019-10-21T22:27:24Z")

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Hi, So I’ve made a package for which I think there is a remote chance that someone might find useful, so I would like to register it. I’m however getting cold feet due to the name I chose back when I just wanted to sta…

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## [ANN: Animations.jl](https://discourse.julialang.org/t/ann-animations-jl/30021)

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**Author:** [@jules](https://discourse.julialang.org/u/jules)\
**Replies:** 7\
**Last updated:** [October 21, 2019, 8:20pm UTC](https://discourse.julialang.org/t/ann-animations-jl/30021 "2019-10-21T20:20:35Z")

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Hi there, Animations.jl is a package for creating (unsurprisingly) animations, useful when you’re making animated visualizations and want to quickly lay down a timeline of changing values together with easing functions.…

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## [Unexpected scope issue](https://discourse.julialang.org/t/unexpected-scope-issue/30145)

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**Author:** [@marcusps](https://discourse.julialang.org/u/marcusps)\
**Replies:** 2\
**Last updated:** [October 21, 2019, 8:20pm UTC](https://discourse.julialang.org/t/unexpected-scope-issue/30145 "2019-10-21T20:20:29Z")

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If I try to run the following a = 1:10 while length(a)\>0 \[0 for i in a\] a = first(a)+1:last(a) end I get an UndefVarError: a not defined error. If I add a global a like so a = 1:10 while length(a)\>0 global a …

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## [Simple Flux model not learning](https://discourse.julialang.org/t/simple-flux-model-not-learning/30138)

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**Author:** [@rsteckel](https://discourse.julialang.org/u/rsteckel)\
**Replies:** 4\
**Last updated:** [October 21, 2019, 7:05pm UTC](https://discourse.julialang.org/t/simple-flux-model-not-learning/30138 "2019-10-21T19:05:21Z")

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I’ve been trying to get a feel for Flux by modeling a simple non-linear function (X^2). At the end of each epoch, I print the model output for 3 (expecting 9), but it seems to converge to ~34 Can anyone see what I’m do…

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## [Python RL environments from Julia](https://discourse.julialang.org/t/python-rl-environments-from-julia/30123)

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**Author:** [@Sarvjeet](https://discourse.julialang.org/u/Sarvjeet)\
**Replies:** 2\
**Last updated:** [October 21, 2019, 6:30pm UTC](https://discourse.julialang.org/t/python-rl-environments-from-julia/30123 "2019-10-21T18:30:59Z")

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Hi there, Since most of the reinforcement learning environments for robotics etc. applications are available in Python so I was wondering if I could implement RL algorithms in Julia and still train those agents written …

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## [Bug? shuffle() breaks normalisation test](https://discourse.julialang.org/t/bug-shuffle-breaks-normalisation-test/29976)

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**Author:** [@dcastel](https://discourse.julialang.org/u/dcastel)\
**Replies:** 8\
**Last updated:** [October 21, 2019, 5:53pm UTC](https://discourse.julialang.org/t/bug-shuffle-breaks-normalisation-test/29976 "2019-10-21T17:53:08Z")

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Hi all, I think I found a Julia bug (Version 1.1.0) I stumbled upon when writing a function for checking whether a tensor is normalized. I wrote tests for it and it seems (somewhat, sometimes) reproducible. It comes do…

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## [Use a Histogram as a function](https://discourse.julialang.org/t/use-a-histogram-as-a-function/30059)

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**Author:** [@bobweek](https://discourse.julialang.org/u/bobweek)\
**Replies:** 4\
**Last updated:** [October 21, 2019, 4:51pm UTC](https://discourse.julialang.org/t/use-a-histogram-as-a-function/30059 "2019-10-21T16:51:24Z")

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I would like to see built-in functionality that allows me to use a Histogram as a function that returns the weight of the histogram at a given point in state space. The closest thing i can find is the kde() function fr…

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## [What's going on with the installation of HTTP package?](https://discourse.julialang.org/t/whats-going-on-with-the-installation-of-http-package/30137)

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**Author:** [@Steven\_Sagaert](https://discourse.julialang.org/u/Steven_Sagaert)\
**Replies:** 1\
**Last updated:** [October 21, 2019, 3:41pm UTC](https://discourse.julialang.org/t/whats-going-on-with-the-installation-of-http-package/30137 "2019-10-21T15:41:34Z")

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Hi, I upgraded an old project from julia 0.6 to 0.7. I could resolve most of the deprecations but I ran into the problem that I was using the package HttpServer.jl and that cannot be installed anymore via Pkg. So I trie…

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## [Improving Distributions.jl type consistency](https://discourse.julialang.org/t/improving-distributions-jl-type-consistency/30082)

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**Author:** [@cscherrer](https://discourse.julialang.org/u/cscherrer)\
**Replies:** 2\
**Last updated:** [October 21, 2019, 1:49pm UTC](https://discourse.julialang.org/t/improving-distributions-jl-type-consistency/30082 "2019-10-21T13:49:13Z")

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The rand(dist, n::Int) method is really handy, but there’s a lot of irregularity in the type that’s returned. Ideally we’d have some type A with typeof(rand(dist, n::Int)) == A{typeof(rand(dist)), n} Having an identity…

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## [Number of nodes and Relative Gap](https://discourse.julialang.org/t/number-of-nodes-and-relative-gap/30133)

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**Author:** [@angeloaliano1](https://discourse.julialang.org/u/angeloaliano1)\
**Replies:** 1\
**Last updated:** [October 21, 2019, 1:40pm UTC](https://discourse.julialang.org/t/number-of-nodes-and-relative-gap/30133 "2019-10-21T13:40:26Z")

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Dear users, I am with Julia 1.0.4, JuMP version 0.19 and using the MathOptInterface to solve a integer model. According to the documentation in Reference · MathOptInterface the relative Gap and the number of nodes resea…

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## [Question with DiffEqBiological](https://discourse.julialang.org/t/question-with-diffeqbiological/30119)

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**Author:** [@David\_Wang](https://discourse.julialang.org/u/David_Wang)\
**Replies:** 5\
**Last updated:** [October 21, 2019, 1:11pm UTC](https://discourse.julialang.org/t/question-with-diffeqbiological/30119 "2019-10-21T13:11:40Z")

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Hi all, I have been running into a problem with the DiffEqBiological package. The following code always returns “ERROR: LoadError: Base.Meta.ParseError(”+1")": rn = @reaction\_network begin 1.0, 0 → M end whereas th…

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