# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1804

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

**Page:** 1805

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## [How to best tackle "Unsatisfiable requirements" type errors while adding packages?](https://discourse.julialang.org/t/how-to-best-tackle-unsatisfiable-requirements-type-errors-while-adding-packages/35803)

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**Author:** [@bashonubuntu](https://discourse.julialang.org/u/bashonubuntu)\
**Replies:** 1\
**Last updated:** [March 10, 2020, 10:38pm UTC](https://discourse.julialang.org/t/how-to-best-tackle-unsatisfiable-requirements-type-errors-while-adding-packages/35803 "2020-03-10T22:38:28Z")

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Hello all, This may be a simple issue for some but this is the first time I encountered something like this while adding packages on a fresh julia install. I tried upgrading to 1.3.1 yesterday from 1.2.0 and was getting…

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## [Repeat with y as k](https://discourse.julialang.org/t/repeat-with-y-as-k/35771)

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**Author:** [@brett\_knoss](https://discourse.julialang.org/u/brett_knoss)\
**Replies:** 11\
**Last updated:** [March 10, 2020, 10:30pm UTC](https://discourse.julialang.org/t/repeat-with-y-as-k/35771 "2020-03-10T22:30:44Z")

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d = .05 n = .01 g = .015 s = .3 k=6 yn( k, s, d, g,) = k-(d+n+g)\*k + s\*k^(1/3) I have this function, and it calculates yn= 6.09514 . Now I would like to replace k with yn, and find a new yn, and repeat that 50 times.

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## [Generate a dataset](https://discourse.julialang.org/t/generate-a-dataset/35812)

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**Author:** [@STHossain](https://discourse.julialang.org/u/STHossain)\
**Replies:** 4\
**Last updated:** [March 10, 2020, 9:31pm UTC](https://discourse.julialang.org/t/generate-a-dataset/35812 "2020-03-10T21:31:33Z")

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I am sorry maybe my title of the problem is probably not so appropriate, but here is the problem. So I have some arrays of categorical or boolean values and I want to create a combination of all of them and form an array…

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## [CBC and CLP solver version with JuMP](https://discourse.julialang.org/t/cbc-and-clp-solver-version-with-jump/35795)

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**Author:** [@bandaya](https://discourse.julialang.org/u/bandaya)\
**Replies:** 2\
**Last updated:** [March 10, 2020, 9:17pm UTC](https://discourse.julialang.org/t/cbc-and-clp-solver-version-with-jump/35795 "2020-03-10T21:17:33Z")

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I am running an optimization problem with CBC solver but it is taking forever with around 1100 binary variables. The same problem is solved in about 2 minutes if I reduce the number of variables to 900. I suspect that t…

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## [BUG REPORT - Left Margin not working with Plots using PlotlyJS backend](https://discourse.julialang.org/t/bug-report-left-margin-not-working-with-plots-using-plotlyjs-backend/35808)

<div class="topic-metadata">

**Author:** [@jman87](https://discourse.julialang.org/u/jman87)\
**Replies:** 6\
**Last updated:** [March 10, 2020, 9:02pm UTC](https://discourse.julialang.org/t/bug-report-left-margin-not-working-with-plots-using-plotlyjs-backend/35808 "2020-03-10T21:02:56Z")

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It appears that when using the Plots package with the PlotlyJS backend, the left margin does not operate correctly. Since the left and the bottom are where the Y and X axex reside, one would assume the margins should be…

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## [SpecialFunctions.jl Successor](https://discourse.julialang.org/t/specialfunctions-jl-successor/35704)

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**Author:** [@Mason](https://discourse.julialang.org/u/Mason)\
**Replies:** 20\
**Last updated:** [March 10, 2020, 8:52pm UTC](https://discourse.julialang.org/t/specialfunctions-jl-successor/35704 "2020-03-10T20:52:56Z")

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Currently, the definitive Julia package for special functions is SpecialFunctions.jl, but it’s now being signalled that PRs adding functionality to it should be taken elsewhere because the package is mostly just for wrap…

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## [Diff missing vs nothing](https://discourse.julialang.org/t/diff-missing-vs-nothing/35806)

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**Author:** [@kimran](https://discourse.julialang.org/u/kimran)\
**Replies:** 1\
**Last updated:** [March 10, 2020, 6:22pm UTC](https://discourse.julialang.org/t/diff-missing-vs-nothing/35806 "2020-03-10T18:22:45Z")

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What is the difference and the idea behind the difference? I saw somewhere that missing is for data and nothing for everything else. But why do we not just use either missing xor nothing for all null/missing values

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## [Simple optimization problem via flux](https://discourse.julialang.org/t/simple-optimization-problem-via-flux/35805)

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**Author:** [@samantp](https://discourse.julialang.org/u/samantp)\
**Replies:** 0\
**Last updated:** [March 10, 2020, 5:41pm UTC](https://discourse.julialang.org/t/simple-optimization-problem-via-flux/35805 "2020-03-10T17:41:37Z")

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I have a prediction function, called NTCP which takes several fixed input parameters: dpf,nf,ab. It also takes in some parameters that I am looking to optimize: n, TD, Y as well as my input data dvh\_all. The fixed parame…

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## [I am very happy of Julia/Genie](https://discourse.julialang.org/t/i-am-very-happy-of-julia-genie/35804)

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**Author:** [@Darione](https://discourse.julialang.org/u/Darione)\
**Replies:** 0\
**Last updated:** [March 10, 2020, 5:39pm UTC](https://discourse.julialang.org/t/i-am-very-happy-of-julia-genie/35804 "2020-03-10T17:39:17Z")

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I am very happy today. I bought a small 4 euro VPS per month: linux ubuntu 64, 1G of RAM, 20G of HD, 1 core. I installed Julia and Genie/JLD2 there (fastly and without problems). I copied my web app on this minimal se…

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## [How can I improve the speed of large matrix multiplication](https://discourse.julialang.org/t/how-can-i-improve-the-speed-of-large-matrix-multiplication/35616)

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**Author:** [@zxjroger](https://discourse.julialang.org/u/zxjroger)\
**Replies:** 6\
**Last updated:** [March 10, 2020, 5:17pm UTC](https://discourse.julialang.org/t/how-can-i-improve-the-speed-of-large-matrix-multiplication/35616 "2020-03-10T17:17:28Z")

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I have some functions involving large matrix multiplication in my code. A sample code is as follows. function foo1() temp = Array\[\] for i = 1:1000 push!(temp, randn(400,400)\*randn(400,1000)) end end …

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## [How to compute the correlation between elements in an array of arrays?](https://discourse.julialang.org/t/how-to-compute-the-correlation-between-elements-in-an-array-of-arrays/35763)

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**Author:** [@zxjroger](https://discourse.julialang.org/u/zxjroger)\
**Replies:** 4\
**Last updated:** [March 10, 2020, 5:15pm UTC](https://discourse.julialang.org/t/how-to-compute-the-correlation-between-elements-in-an-array-of-arrays/35763 "2020-03-10T17:15:53Z")

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Suppose that I have the following array of vectors. temp = Matrix{Vector{Float64}}(undef, 3, 1000) for i = 1:3 for j = 1:1000 temp\[i,j\] = rand(10) end end Now I want to compute the correlation between t…

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## [Is there a newest TF.jl to support TensorFlow 2.0 and cuda 10.2?](https://discourse.julialang.org/t/is-there-a-newest-tf-jl-to-support-tensorflow-2-0-and-cuda-10-2/35787)

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**Author:** [@Yan](https://discourse.julialang.org/u/Yan)\
**Replies:** 0\
**Last updated:** [March 10, 2020, 6:33am UTC](https://discourse.julialang.org/t/is-there-a-newest-tf-jl-to-support-tensorflow-2-0-and-cuda-10-2/35787 "2020-03-10T06:33:21Z")

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Is there a newest TF.jl to support TensorFlow 2.0 and cuda 10.2 ? or any other Julia API solution targeting to tensorflow 2 like keras ? Oh, TF2 has already included tf.keras.

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## [Error when performing join on Distributed Tables (JuliaDB)](https://discourse.julialang.org/t/error-when-performing-join-on-distributed-tables-juliadb/35800)

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**Author:** [@Jakob](https://discourse.julialang.org/u/Jakob)\
**Replies:** 0\
**Last updated:** [March 10, 2020, 2:40pm UTC](https://discourse.julialang.org/t/error-when-performing-join-on-distributed-tables-juliadb/35800 "2020-03-10T14:40:53Z")

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Hi, I get the error message shown below when trying to do the following out-of-core join: t209\_expanded = join(t209, t201\_sel, broadcast = :right, how = :left, lkey = :appln\_id, rkey = :appln\_id) Both input tables are…

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## [Azure Data Scince VM - includes Julia](https://discourse.julialang.org/t/azure-data-scince-vm-includes-julia/35794)

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**Author:** [@johnh](https://discourse.julialang.org/u/johnh)\
**Replies:** 1\
**Last updated:** [March 10, 2020, 11:35am UTC](https://discourse.julialang.org/t/azure-data-scince-vm-includes-julia/35794 "2020-03-10T11:35:50Z")

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I am in a trining course at Microsoft in the UK, on applying AI Azure has a canned VM available for Data Science. It has Julia pre-installed! Pat on the abck to MS. I have not go the version yet though as it is just …

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## [How to read in Julia a "pickled" numpy multiarray?](https://discourse.julialang.org/t/how-to-read-in-julia-a-pickled-numpy-multiarray/35791)

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**Author:** [@sylvaticus](https://discourse.julialang.org/u/sylvaticus)\
**Replies:** 3\
**Last updated:** [March 10, 2020, 9:34am UTC](https://discourse.julialang.org/t/how-to-read-in-julia-a-pickled-numpy-multiarray/35791 "2020-03-10T09:34:53Z")

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I am trying to port to Julia a Python exercise where however the first step is in reading some “pickled” data. If I open the file with a text file I notice it is a binary file with stamped “numpy.core.multiarray” on th…

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## [Is there any replacement in Julia for ImageDataGenerator](https://discourse.julialang.org/t/is-there-any-replacement-in-julia-for-imagedatagenerator/35785)

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**Author:** [@Eldho.Ashna](https://discourse.julialang.org/u/Eldho.Ashna)\
**Replies:** 8\
**Last updated:** [March 10, 2020, 8:45am UTC](https://discourse.julialang.org/t/is-there-any-replacement-in-julia-for-imagedatagenerator/35785 "2020-03-10T08:45:23Z")

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Hi, I was trying to rewrite a python code of cat vs dog classification into julia. In the python code, I have the following: from keras.preprocessing.image import ImageDataGenerator # All images will be rescaled by 1.…

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## [Juno's outline pane cannot restore its position within the Project pane (when it is docked into)](https://discourse.julialang.org/t/junos-outline-pane-cannot-restore-its-position-within-the-project-pane-when-it-is-docked-into/35790)

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**Author:** [@DIzer](https://discourse.julialang.org/u/DIzer)\
**Replies:** 0\
**Last updated:** [March 10, 2020, 8:23am UTC](https://discourse.julialang.org/t/junos-outline-pane-cannot-restore-its-position-within-the-project-pane-when-it-is-docked-into/35790 "2020-03-10T08:23:34Z")

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The position is saved (before Atom quitting), but it cannot be restored after the editor start - visually it looks as some blink at the right position,then its turns into usual tabbed pane with the Project pane. It sems…

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## [Is it possible perform reverse mode differentiation (Flux.jl with Zygote.jl) of a forward mode differentiation result (e.g. ForwardDiff)?](https://discourse.julialang.org/t/is-it-possible-perform-reverse-mode-differentiation-flux-jl-with-zygote-jl-of-a-forward-mode-differentiation-result-e-g-forwarddiff/30945)

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**Author:** [@Sleort](https://discourse.julialang.org/u/Sleort)\
**Replies:** 3\
**Last updated:** [March 10, 2020, 5:41am UTC](https://discourse.julialang.org/t/is-it-possible-perform-reverse-mode-differentiation-flux-jl-with-zygote-jl-of-a-forward-mode-differentiation-result-e-g-forwarddiff/30945 "2020-03-10T05:41:45Z")

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Say I have some function f: \\mathbb{R}^m \\times \\mathbb{R} \\to \\mathbb{R}^n, i.e. f(\\theta, x) is some vector for a given set of parameters \\theta and a scalar x. I would now like to calculate the gradient \\nabla\_\\theta …

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## [How to avoid large movement of data when using remotecall\_fetch?](https://discourse.julialang.org/t/how-to-avoid-large-movement-of-data-when-using-remotecall-fetch/35746)

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**Author:** [@zxjroger](https://discourse.julialang.org/u/zxjroger)\
**Replies:** 0\
**Last updated:** [March 9, 2020, 6:41am UTC](https://discourse.julialang.org/t/how-to-avoid-large-movement-of-data-when-using-remotecall-fetch/35746 "2020-03-09T06:41:53Z")

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I wrote a code to solve 10k linear programming problems in parallel. I timed this code on a computer with nprocs()=4. Ideally, it should be three times faster than non-parallel code, however, it is only two times faster.…

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## [DarkIntegers, a pure Julia library for modulo integer and polynomial arithmetic](https://discourse.julialang.org/t/darkintegers-a-pure-julia-library-for-modulo-integer-and-polynomial-arithmetic/35774)

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**Author:** [@fjarri](https://discourse.julialang.org/u/fjarri)\
**Replies:** 4\
**Last updated:** [March 9, 2020, 10:54pm UTC](https://discourse.julialang.org/t/darkintegers-a-pure-julia-library-for-modulo-integer-and-polynomial-arithmetic/35774 "2020-03-09T22:54:18Z")

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Github: GitHub - nucypher/DarkIntegers.jl: A modulo arithmetic toolbox for integers and polynomials Docs: Home · DarkIntegers.jl This is a side project developed for prototyping of various cryptographic schemes at my j…

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## [AutoMLPipeline.jl makes it easy to create complexed ML pipeline structures](https://discourse.julialang.org/t/automlpipeline-jl-makes-it-easy-to-create-complexed-ml-pipeline-structures/35308)

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**Author:** [@ppalmes](https://discourse.julialang.org/u/ppalmes)\
**Replies:** 23\
**Last updated:** [March 9, 2020, 10:19pm UTC](https://discourse.julialang.org/t/automlpipeline-jl-makes-it-easy-to-create-complexed-ml-pipeline-structures/35308 "2020-03-09T22:19:45Z")

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As part of educating myself with macro programming, I tried to apply the idea of manipulating pipeline expression so that it becomes trivial to perform feature extraction, feature selection, pipeline structure optimizati…

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## [Matrix square root of known positive semi-definite matrix does not exist?](https://discourse.julialang.org/t/matrix-square-root-of-known-positive-semi-definite-matrix-does-not-exist/35766)

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**Author:** [@torgo](https://discourse.julialang.org/u/torgo)\
**Replies:** 9\
**Last updated:** [March 9, 2020, 10:24pm UTC](https://discourse.julialang.org/t/matrix-square-root-of-known-positive-semi-definite-matrix-does-not-exist/35766 "2020-03-09T22:24:14Z")

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In the following example, I believe that the matrix C should be positive semi-definite by construction. (Note that the matrix B is positive semi-definite.) As a consequence, it should have a unique positive semi-definit…

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## [Strange codegen for type with small union fields](https://discourse.julialang.org/t/strange-codegen-for-type-with-small-union-fields/35773)

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**Author:** [@Christian\_Rorvik](https://discourse.julialang.org/u/Christian_Rorvik)\
**Replies:** 0\
**Last updated:** [March 9, 2020, 9:43pm UTC](https://discourse.julialang.org/t/strange-codegen-for-type-with-small-union-fields/35773 "2020-03-09T21:43:00Z")

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Context Working on an intrusive containers package, for users (like me) who need allocation free datastructures. Putting together the very beginnings of some expertiments I spotted some strange codegen behavior. Julia V…

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## [DataFrames not showing value](https://discourse.julialang.org/t/dataframes-not-showing-value/35743)

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**Author:** [@brett\_knoss](https://discourse.julialang.org/u/brett_knoss)\
**Replies:** 11\
**Last updated:** [March 9, 2020, 9:25pm UTC](https://discourse.julialang.org/t/dataframes-not-showing-value/35743 "2020-03-09T21:25:49Z")

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d = .05 n = .01 g = .015 s = .3 k = 6 i=s t=0:50 yn= function(t) ((y-k)+I\*t) using DataFrames df = DataFrame(A = yn, B = t) print(df) When I run this, istead of giving each value of yn for each value of t, it has #1…

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## [Multiple type declarations with if-else](https://discourse.julialang.org/t/multiple-type-declarations-with-if-else/35759)

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**Author:** [@ykc](https://discourse.julialang.org/u/ykc)\
**Replies:** 8\
**Last updated:** [March 9, 2020, 8:51pm UTC](https://discourse.julialang.org/t/multiple-type-declarations-with-if-else/35759 "2020-03-09T20:51:12Z")

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I understand the proper practice is to pre-allocate outputs, but why wouldn’t the following work? function f() if 1 == 1 x::Float64 = 1.0 else x::Float64 = 2.0 end return x end This retu…

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## [Custom Type for lazy kernel operations on AbstractArrays, ho can i improve it?](https://discourse.julialang.org/t/custom-type-for-lazy-kernel-operations-on-abstractarrays-ho-can-i-improve-it/35764)

<div class="topic-metadata">

**Author:** [@francesco.alemanno](https://discourse.julialang.org/u/francesco.alemanno)\
**Replies:** 3\
**Last updated:** [March 9, 2020, 8:05pm UTC](https://discourse.julialang.org/t/custom-type-for-lazy-kernel-operations-on-abstractarrays-ho-can-i-improve-it/35764 "2020-03-09T20:05:01Z")

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Hi guys is there any way to make this performant? it looks like a super useful type see Example of usage Type Definition struct KernelOp{T,N,S} \<: AbstractArray{T,N} parent::S op::Function opdims::CartesianI…

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## [Reading from a KNetArray within a GPU kernel function](https://discourse.julialang.org/t/reading-from-a-knetarray-within-a-gpu-kernel-function/35767)

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**Author:** [@dfenn](https://discourse.julialang.org/u/dfenn)\
**Replies:** 0\
**Last updated:** [March 9, 2020, 7:46pm UTC](https://discourse.julialang.org/t/reading-from-a-knetarray-within-a-gpu-kernel-function/35767 "2020-03-09T19:46:40Z")

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Is it possible to use KNetArrays from within a custom GPU kernel function? The following MWE fails: using Knet using GPUArrays knArray = KnetArray(rand(4,4)) function kernel(state, knArray) temp = knArray\[1\] …

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## [Patching without adding dependencies](https://discourse.julialang.org/t/patching-without-adding-dependencies/35762)

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**Author:** [@jonniedie](https://discourse.julialang.org/u/jonniedie)\
**Replies:** 2\
**Last updated:** [March 9, 2020, 6:32pm UTC](https://discourse.julialang.org/t/patching-without-adding-dependencies/35762 "2020-03-09T18:32:22Z")

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Let’s say I created some package MyPackage that I would like to interact with a package TheirPackage that I did not create. Is there any way to override some of the functions of TheirPackage without having to add TheirPa…

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## [Simplest way to have numerical FOC of a function?](https://discourse.julialang.org/t/simplest-way-to-have-numerical-foc-of-a-function/35754)

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**Author:** [@sylvaticus](https://discourse.julialang.org/u/sylvaticus)\
**Replies:** 1\
**Last updated:** [March 9, 2020, 3:22pm UTC](https://discourse.julialang.org/t/simplest-way-to-have-numerical-foc-of-a-function/35754 "2020-03-09T15:22:37Z")

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I have the following function for which I need to find the First Order Conditions with respect to one parameter, let’s say \\mathbb{u}: J(u,v,Y,λ) = sum(skipmissing((Y-(u \* v')) .^ 2))/2 + (λ/2) \* (norm(u)^2 + norm(v)^2…

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## [How to solve this error while installing SCENRED2](https://discourse.julialang.org/t/how-to-solve-this-error-while-installing-scenred2/35413)

<div class="topic-metadata">

**Author:** [@SAH](https://discourse.julialang.org/u/SAH)\
**Replies:** 2\
**Last updated:** [March 9, 2020, 2:41pm UTC](https://discourse.julialang.org/t/how-to-solve-this-error-while-installing-scenred2/35413 "2020-03-09T14:41:29Z")

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I am trying to add a scenario reduction package \[available here\] in Julia and getting an error. In fact, I run these 2 lines as discribed in the link: julia\> Pkg.clone("https://github.com/trigaut/Scenred2.jl.git") julia\>…

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