# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?page=426

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**Page:** 427

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## [Querying JuMP solutions - results out of order](https://discourse.julialang.org/t/querying-jump-solutions-results-out-of-order/45301)

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**Author:** [@fnbillimoria](https://discourse.julialang.org/u/fnbillimoria)\
**Replies:** 2\
**Last updated:** [August 27, 2020, 7:06am UTC](https://discourse.julialang.org/t/querying-jump-solutions-results-out-of-order/45301 "2020-08-27T07:06:06Z")

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Hello, I have created a JuMP model, and wish to source and sort the results. The JuMP model is created via a call to a function with results stored as below. I wish to obtain results for a variable array called pg. Ho…

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## [Updating Cholesky Factorization submatrix](https://discourse.julialang.org/t/updating-cholesky-factorization-submatrix/28913)

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**Author:** [@charshaw](https://discourse.julialang.org/u/charshaw)\
**Replies:** 7\
**Last updated:** [August 26, 2020, 5:05pm UTC](https://discourse.julialang.org/t/updating-cholesky-factorization-submatrix/28913 "2020-08-26T17:05:00Z")

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I have a positive semidefinite matrix A \\in \\mathbb{R}^{n \\times n} and its Cholesky factorization is A = L L^T. I would like to update the Cholesky factorization by removing the last row and column of L. What is the co…

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## [ModelingToolkit.jl: '===' comparison on Operations(/Expressions)](https://discourse.julialang.org/t/modelingtoolkit-jl-comparison-on-operations-expressions/45559)

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**Author:** [@NumHack](https://discourse.julialang.org/u/NumHack)\
**Replies:** 2\
**Last updated:** [August 26, 2020, 4:24pm UTC](https://discourse.julialang.org/t/modelingtoolkit-jl-comparison-on-operations-expressions/45559 "2020-08-26T16:24:10Z")

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Hi, Since this is my first post, I want to thank everyone involved in the creation of the Julia language. I would like to compare Operation/Expression objects, my initial goal being to replace sub-(Operation/Expression…

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## [(geometry)Rotating Calipers / Oriented Minimum Bounding Box?](https://discourse.julialang.org/t/geometry-rotating-calipers-oriented-minimum-bounding-box/44058)

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**Author:** [@anon92994695](https://discourse.julialang.org/u/anon92994695)\
**Replies:** 5\
**Last updated:** [August 26, 2020, 10:55am UTC](https://discourse.julialang.org/t/geometry-rotating-calipers-oriented-minimum-bounding-box/44058 "2020-08-26T10:55:50Z")

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Are there any implementations for, rotating calipers algorithm or any oriented minimum bounding box here in Julia? I could whip one up if not, but preferably one of you wizards has one out there somewhere.

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## [Can pyplot scatterplots take values smaller than 1e-16?](https://discourse.julialang.org/t/can-pyplot-scatterplots-take-values-smaller-than-1e-16/45438)

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**Author:** [@nicolas](https://discourse.julialang.org/u/nicolas)\
**Replies:** 5\
**Last updated:** [August 26, 2020, 8:28am UTC](https://discourse.julialang.org/t/can-pyplot-scatterplots-take-values-smaller-than-1e-16/45438 "2020-08-26T08:28:52Z")

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When running the following code, using Plots pyplot() x = exp.(randn(100) .- 36) y = exp.(randn(100) .- 36) plot(x,y, xscale = :log10, yscale = :log10, markershape = :square) The lines show perfectly, but funnily enoug…

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## [BK tree (graph) search algorithm](https://discourse.julialang.org/t/bk-tree-graph-search-algorithm/45529)

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**Author:** [@mthelm85](https://discourse.julialang.org/u/mthelm85)\
**Replies:** 1\
**Last updated:** [August 25, 2020, 11:04pm UTC](https://discourse.julialang.org/t/bk-tree-graph-search-algorithm/45529 "2020-08-25T23:04:50Z")

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I’m attempting to implement BK trees via LightGraphs and SimpleWeightedGraphs and I’m struggling to figure out how to write a function (doesn’t work properly) to perform the search. I have a simple function that builds t…

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## [Creating a video from a stack of Images](https://discourse.julialang.org/t/creating-a-video-from-a-stack-of-images/646)

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**Author:** [@vchuravy](https://discourse.julialang.org/u/vchuravy)\
**Replies:** 11\
**Last updated:** [August 26, 2020, 12:51am UTC](https://discourse.julialang.org/t/creating-a-video-from-a-stack-of-images/646 "2020-08-26T00:51:07Z")

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VideoIO.jl only seems to have the capabilities of reading in video with ffmpeg. I couldn’t find any options to create a Video so I was wondering if I am missing something. I know @sdanisch is exporting to png files fir…

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## [\[ANN\] Turing.jl 0.14.0](https://discourse.julialang.org/t/ann-turing-jl-0-14-0/45520)

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**Author:** [@cpfiffer](https://discourse.julialang.org/u/cpfiffer)\
**Replies:** 0\
**Last updated:** [August 25, 2020, 5:16pm UTC](https://discourse.julialang.org/t/ann-turing-jl-0-14-0/45520 "2020-08-25T17:16:47Z")

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Hey folks, It’s been a while since our last release, which we’re hoping to avoid entirely. The Turing-verse is mostly adapting Colprac going forward, which means we’ll be flagging releases much more frequently to keep u…

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## [Best way to create a wrapper for C library for Continuous version of Tensor Train](https://discourse.julialang.org/t/best-way-to-create-a-wrapper-for-c-library-for-continuous-version-of-tensor-train/45479)

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**Author:** [@mleprovost](https://discourse.julialang.org/u/mleprovost)\
**Replies:** 3\
**Last updated:** [August 25, 2020, 3:14pm UTC](https://discourse.julialang.org/t/best-way-to-create-a-wrapper-for-c-library-for-continuous-version-of-tensor-train/45479 "2020-08-25T15:14:55Z")

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Hello, I would like to create a wrapper for the C library https://github.com/goroda/Compressed-Continuous-Computation that implements a low-rank approximation of multi-dimensional functions in the same spirit as ApproxF…

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## [How to change legends place with Plots, gr()?](https://discourse.julialang.org/t/how-to-change-legends-place-with-plots-gr/7294)

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**Author:** [@cserteGT3](https://discourse.julialang.org/u/cserteGT3)\
**Replies:** 26\
**Last updated:** [August 25, 2020, 10:46am UTC](https://discourse.julialang.org/t/how-to-change-legends-place-with-plots-gr/7294 "2020-08-25T10:46:12Z")

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I’m using Plots and GR, and can’t find a way to change the legends location in a plot. As I understand currently I can’t do it with Plots, there’s no keyword argument for it (correct me if I’m wrong). Can someone please…

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## [How to register a function with parameter in JuMP](https://discourse.julialang.org/t/how-to-register-a-function-with-parameter-in-jump/45457)

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**Author:** [@Behemoth-s](https://discourse.julialang.org/u/Behemoth-s)\
**Replies:** 2\
**Last updated:** [August 25, 2020, 2:10am UTC](https://discourse.julialang.org/t/how-to-register-a-function-with-parameter-in-jump/45457 "2020-08-25T02:10:25Z")

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Here I have some variables and parameters model = Model(Ipopt.Optimizer) @variable(model, x\[1:2\]) p = \[4, 6\] I want to register a function with parameter in JuMP to do something like this bellow. function f(x, p) …

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## [Taking zygote gradient on function with ! operator fails on gpu](https://discourse.julialang.org/t/taking-zygote-gradient-on-function-with-operator-fails-on-gpu/45481)

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**Author:** [@reid](https://discourse.julialang.org/u/reid)\
**Replies:** 3\
**Last updated:** [August 25, 2020, 1:40am UTC](https://discourse.julialang.org/t/taking-zygote-gradient-on-function-with-operator-fails-on-gpu/45481 "2020-08-25T01:40:09Z")

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ERROR: LoadError: MethodError: no method matching !(::ForwardDiff.Dual{Nothing,Bool,1}) Only happens on gpu, not cpu, which is really confusing me. MWE using Flux masksum(x,y) = sum(.!x \* y) gradient(masksum, \[true,…

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## [Onnx support for Julia ML frameworks](https://discourse.julialang.org/t/onnx-support-for-julia-ml-frameworks/9035)

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**Author:** [@hgeorgako](https://discourse.julialang.org/u/hgeorgako)\
**Replies:** 9\
**Last updated:** [August 24, 2020, 8:35pm UTC](https://discourse.julialang.org/t/onnx-support-for-julia-ml-frameworks/9035 "2020-08-24T20:35:50Z")

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This seems like it’s becoming a thing. https://onnx.ai/getting-started Any packages providing support for this?

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## [Proper structuring of an input data table](https://discourse.julialang.org/t/proper-structuring-of-an-input-data-table/45446)

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**Author:** [@mamo](https://discourse.julialang.org/u/mamo)\
**Replies:** 4\
**Last updated:** [August 24, 2020, 2:53pm UTC](https://discourse.julialang.org/t/proper-structuring-of-an-input-data-table/45446 "2020-08-24T14:53:52Z")

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How to build an input matrix (or a table) which will be sparse. For example: A is 4x4 matrix: A=\[1 . . .; . . 2 3; . 5 . 1; 1 3 . .\] If I use “missing” instead of dots, I have a problem with reading the data and ident…

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## [Failed to obtain the correct phase?](https://discourse.julialang.org/t/failed-to-obtain-the-correct-phase/45350)

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**Author:** [@tomtom](https://discourse.julialang.org/u/tomtom)\
**Replies:** 3\
**Last updated:** [August 24, 2020, 2:07pm UTC](https://discourse.julialang.org/t/failed-to-obtain-the-correct-phase/45350 "2020-08-24T14:07:58Z")

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I’m trying to extract the amplitude, period and phase of a pure sinusoidal signal: using FFTW a = 3cos.(2π/17 .\* (1:4096) .+ 0.2); fa = fft(a)\[1:2048\]; fam = abs.(fa); famfm = findmax(fam) julia\> famfm = findmax(fam) (…

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## [Proper declaration of constraint](https://discourse.julialang.org/t/proper-declaration-of-constraint/45424)

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**Author:** [@mamo](https://discourse.julialang.org/u/mamo)\
**Replies:** 5\
**Last updated:** [August 24, 2020, 1:51pm UTC](https://discourse.julialang.org/t/proper-declaration-of-constraint/45424 "2020-08-24T13:51:39Z")

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Constraint below says for each k, k=1, k=22, k=43 (since k is \< length(TIME)=63) PLEVEL\[1\]\<=… PLEVEL\[22\]\<=… PLEVEL\[43\]\<=… PLEVEL1 is binary. s1\[k in 1:interval:length(TIME) if k\<length(TIME)\], PLEVEL\[k\]-limit\<=M\*PLE…

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## [Julia's offline documentation has no favicon](https://discourse.julialang.org/t/julias-offline-documentation-has-no-favicon/42942)

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**Author:** [@melonedo](https://discourse.julialang.org/u/melonedo)\
**Replies:** 2\
**Last updated:** [August 1, 2020, 3:16pm UTC](https://discourse.julialang.org/t/julias-offline-documentation-has-no-favicon/42942 "2020-08-01T15:16:17Z")

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Julia’s offline documentation has no favicon, while the online version does have one. As I love to use the offline version (which is much faster), this is really annoying. I inspected the index.html and it does not have…

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## [\`CUDA error: out of memory\` with Flux](https://discourse.julialang.org/t/cuda-error-out-of-memory-with-flux/45269)

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**Author:** [@natema](https://discourse.julialang.org/u/natema)\
**Replies:** 4\
**Last updated:** [August 24, 2020, 12:11pm UTC](https://discourse.julialang.org/t/cuda-error-out-of-memory-with-flux/45269 "2020-08-24T12:11:01Z")

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I already posted about this issue here. After moving to Julia 1.5, I still get a similar error. When I run yiyu-test.jl I get ERROR: LoadError: CUDA error: out of memory (code 2, ERROR\_OUT\_OF\_MEMORY) Stacktrace: \[1\] …

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## [Training gets differents results when using Flux.train() inside function](https://discourse.julialang.org/t/training-gets-differents-results-when-using-flux-train-inside-function/45284)

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**Author:** [@german\_brunini](https://discourse.julialang.org/u/german_brunini)\
**Replies:** 2\
**Last updated:** [August 23, 2020, 11:01pm UTC](https://discourse.julialang.org/t/training-gets-differents-results-when-using-flux-train-inside-function/45284 "2020-08-23T23:01:36Z")

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I am training a NN with some synthetic data. I was running everything on REPL and things were going on the right direction, but when I tried to wrap my code inside a function() to use custom training loops, my model(x) …

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## [ERROR: LoadError: MethodError: no method matching isless(::String, ::Int64)](https://discourse.julialang.org/t/error-loaderror-methoderror-no-method-matching-isless-string-int64/45408)

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**Author:** [@mamo](https://discourse.julialang.org/u/mamo)\
**Replies:** 3\
**Last updated:** [August 23, 2020, 10:24pm UTC](https://discourse.julialang.org/t/error-loaderror-methoderror-no-method-matching-isless-string-int64/45408 "2020-08-23T22:24:26Z")

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Send me please your opinion related to the error I received. Thanks! ERROR: LoadError: MethodError: no method matching isless(::String, ::Int64) Closest candidates are: isless(::Missing, ::Any) at missing.jl:87 isl…

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## [Saving a VPTree with JLD](https://discourse.julialang.org/t/saving-a-vptree-with-jld/45425)

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**Author:** [@mthelm85](https://discourse.julialang.org/u/mthelm85)\
**Replies:** 0\
**Last updated:** [August 23, 2020, 5:52pm UTC](https://discourse.julialang.org/t/saving-a-vptree-with-jld/45425 "2020-08-23T17:52:34Z")

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I have some code that builds a number of VPTrees via VPTrees.jl and the building of these trees takes a long time. I’d like to be able to simply load a pre-built tree into a new session rather than having to re-build the…

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## [Stack and unstack in Query.jl](https://discourse.julialang.org/t/stack-and-unstack-in-query-jl/45381)

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**Author:** [@tnederlof](https://discourse.julialang.org/u/tnederlof)\
**Replies:** 5\
**Last updated:** [August 23, 2020, 2:55pm UTC](https://discourse.julialang.org/t/stack-and-unstack-in-query-jl/45381 "2020-08-23T14:55:14Z")

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Something I used a lot when I am in the R/Tidyverse world is spread and gather from tidyr most of which I can replicate using stack and unstack in DataFrames.jl. Within Query.jl is there a way to accomplish this? If not …

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## [Error while trying to replicate a logistic regression problem using FluxML](https://discourse.julialang.org/t/error-while-trying-to-replicate-a-logistic-regression-problem-using-fluxml/26408)

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**Author:** [@richie96](https://discourse.julialang.org/u/richie96)\
**Replies:** 5\
**Last updated:** [August 23, 2020, 1:31pm UTC](https://discourse.julialang.org/t/error-while-trying-to-replicate-a-logistic-regression-problem-using-fluxml/26408 "2020-08-23T13:31:03Z")

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Hi, I have been trying to replicate the code from the following link to understand how to use ML in Julia better https://akaysh.github.io/Logistic-Regression-with-Julia/ While replicating I realized that when I ran th…

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## [Dealing with missing values in DataFrame (again)](https://discourse.julialang.org/t/dealing-with-missing-values-in-dataframe-again/45373)

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**Author:** [@gaspardelanuit](https://discourse.julialang.org/u/gaspardelanuit)\
**Replies:** 5\
**Last updated:** [August 23, 2020, 12:51pm UTC](https://discourse.julialang.org/t/dealing-with-missing-values-in-dataframe-again/45373 "2020-08-23T12:51:54Z")

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I am wondering if there has been progress on the usability of the missing interface. I am trying to write most of my R commands into Julia step by step to build a guide that would have interested people switch over easi…

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## [Computing null space of a Flux Chain](https://discourse.julialang.org/t/computing-null-space-of-a-flux-chain/45359)

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**Author:** [@Jagirhussan](https://discourse.julialang.org/u/Jagirhussan)\
**Replies:** 8\
**Last updated:** [August 22, 2020, 11:32pm UTC](https://discourse.julialang.org/t/computing-null-space-of-a-flux-chain/45359 "2020-08-22T23:32:35Z")

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I have trained a Flux Chain with Dense layers. I would like to determine the null space (the space of input vectors for which the output is zeros(s) ) for this Chain. I am looking for a Julia like way to determine the pr…

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## [Unclear error](https://discourse.julialang.org/t/unclear-error/45356)

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**Author:** [@mamo](https://discourse.julialang.org/u/mamo)\
**Replies:** 2\
**Last updated:** [August 22, 2020, 7:55pm UTC](https://discourse.julialang.org/t/unclear-error/45356 "2020-08-22T19:55:42Z")

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Below, is example 6.2 from the book (Julia Programming for OR) ‘’’ import Pkg Pkg.add(“DataFrames”) Pkg.add(“CSV”) Pkg.add(“JuMP”) Pkg.add(“MathOptInterface”) Pkg.add(“GLPK”) Pkg.add(“Clp”) Pkg.activate(@DIR) Pk…

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## [Websockets server with processed user input](https://discourse.julialang.org/t/websockets-server-with-processed-user-input/45360)

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**Author:** [@KirillGerke](https://discourse.julialang.org/u/KirillGerke)\
**Replies:** 0\
**Last updated:** [August 22, 2020, 10:55am UTC](https://discourse.julialang.org/t/websockets-server-with-processed-user-input/45360 "2020-08-22T10:55:32Z")

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Dear All, I am new to web-stack programming and my naive implementation of websockets server is not working. I took chat server (chat\_explore.jl) from WebSockets.jl examples here (chat\_explore.html is needed to run the …

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## [StackOverflowError trying to fit a difference equation with Turing](https://discourse.julialang.org/t/stackoverflowerror-trying-to-fit-a-difference-equation-with-turing/44349)

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**Author:** [@arnaudmgh](https://discourse.julialang.org/u/arnaudmgh)\
**Replies:** 7\
**Last updated:** [August 21, 2020, 11:21pm UTC](https://discourse.julialang.org/t/stackoverflowerror-trying-to-fit-a-difference-equation-with-turing/44349 "2020-08-21T23:21:51Z")

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I am trying to sample a difference equation using Turing but encounter errors. Basically, it’s a SIR model that solves fine, with a quick solver function written below (I wrote my own very simple solver to understand th…

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## [Scalar getindex during Flux gradient computation](https://discourse.julialang.org/t/scalar-getindex-during-flux-gradient-computation/45325)

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**Author:** [@HenriDeh](https://discourse.julialang.org/u/HenriDeh)\
**Replies:** 0\
**Last updated:** [August 21, 2020, 3:34pm UTC](https://discourse.julialang.org/t/scalar-getindex-during-flux-gradient-computation/45325 "2020-08-21T15:34:47Z")

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I have a issue with a GPU scalar getindex during gradient computation with Flux. Problem is, I just can’t reproduce the problem with a simpler MWE. I swear I tried so hard. So here’s a chunk of the code and what I unders…

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## [Smooth delta functions to compute Jacobian and Hessian from samples](https://discourse.julialang.org/t/smooth-delta-functions-to-compute-jacobian-and-hessian-from-samples/45282)

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**Author:** [@mleprovost](https://discourse.julialang.org/u/mleprovost)\
**Replies:** 10\
**Last updated:** [August 21, 2020, 10:16am UTC](https://discourse.julialang.org/t/smooth-delta-functions-to-compute-jacobian-and-hessian-from-samples/45282 "2020-08-21T10:16:18Z")

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Hello, Given an expensive function \\boldsymbol{G} :\\mathbb{R}^n \\xrightarrow{} \\mathbb{R}^m whose value is known at samples \\boldsymbol{x}^1,\\ldots, \\boldsymbol{x}^N, I would like to compute the Jacobian and Hessian a…

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