# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?page=474

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**Page:** 475

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## [Strange Behaviour of Stiff Solvers in DifferentialEquations.jl](https://discourse.julialang.org/t/strange-behaviour-of-stiff-solvers-in-differentialequations-jl/31407)

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**Author:** [@anodos](https://discourse.julialang.org/u/anodos)\
**Replies:** 2\
**Last updated:** [November 23, 2019, 7:50am UTC](https://discourse.julialang.org/t/strange-behaviour-of-stiff-solvers-in-differentialequations-jl/31407 "2019-11-23T07:50:17Z")

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I have run into a surprising problem when using stiff solvers in DifferentialEquations.jl. It appears to be related to the automatic differentiation. Basically, when using the stiff solvers, I appear to be unable to assi…

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## [Dynamic web pages with Interact and Mux](https://discourse.julialang.org/t/dynamic-web-pages-with-interact-and-mux/31360)

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**Author:** [@KajWiik](https://discourse.julialang.org/u/KajWiik)\
**Replies:** 1\
**Last updated:** [November 22, 2019, 9:12pm UTC](https://discourse.julialang.org/t/dynamic-web-pages-with-interact-and-mux/31360 "2019-11-22T21:12:05Z")

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I am trying to write a web GUI controlling some instruments. The basic widgets are working but I’d need to print some variables in real time. MWE follows: using Mux, Interact, CSSUtil s = slider(0:0.01:1, label="Slider"…

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## [Package MNIST not found](https://discourse.julialang.org/t/package-mnist-not-found/31352)

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**Author:** [@compleat](https://discourse.julialang.org/u/compleat)\
**Replies:** 4\
**Last updated:** [November 22, 2019, 5:10pm UTC](https://discourse.julialang.org/t/package-mnist-not-found/31352 "2019-11-22T17:10:51Z")

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Attempting to follow the example on https://fluxml.ai/Flux.jl/v0.2/examples/logreg.html for ‘Simple MNIST’ the package ‘MNIST’ cannot be found using Pkg.add \[ I have spent hours just trying to run the first line of th…

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## [StatsPlots dendrogram on the right side or rotated](https://discourse.julialang.org/t/statsplots-dendrogram-on-the-right-side-or-rotated/31348)

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**Author:** [@oheil](https://discourse.julialang.org/u/oheil)\
**Replies:** 3\
**Last updated:** [November 22, 2019, 12:39pm UTC](https://discourse.julialang.org/t/statsplots-dendrogram-on-the-right-side-or-rotated/31348 "2019-11-22T12:39:42Z")

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I try to generate a heatmap with clustered rows and columns and want the dendrograms displayed on top and on the side. The top dendrogram is no problem, but I can’t find a way to create a dendrogram which is displayed fr…

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## [Plots.jl/Makie.jl tick locations?](https://discourse.julialang.org/t/plots-jl-makie-jl-tick-locations/31371)

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**Author:** [@Raf](https://discourse.julialang.org/u/Raf)\
**Replies:** 1\
**Last updated:** [November 22, 2019, 7:17am UTC](https://discourse.julialang.org/t/plots-jl-makie-jl-tick-locations/31371 "2019-11-22T07:17:14Z")

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I’m wondering if there is a way of specifying the location of the ticks/ labels within each x/y value - ie start, center, end. For an example application, sometimes you want the month to show as the whole period, not th…

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## [Trying to understand the "gradient()" function from the Flux.jl/Zygote.jl package](https://discourse.julialang.org/t/trying-to-understand-the-gradient-function-from-the-flux-jl-zygote-jl-package/31328)

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**Author:** [@rapasite](https://discourse.julialang.org/u/rapasite)\
**Replies:** 4\
**Last updated:** [November 21, 2019, 9:19pm UTC](https://discourse.julialang.org/t/trying-to-understand-the-gradient-function-from-the-flux-jl-zygote-jl-package/31328 "2019-11-21T21:19:45Z")

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Hi there, need some help to dig into https://github.com/FluxML/Zygote.jl/blob/master/src/compiler/interface.jl. So it start like this: function gradient(f, args...) y, back = pullback(f, args...) return back(sensi…

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## [Porting an example from QuantEcon.jl to POMDPs.jl](https://discourse.julialang.org/t/porting-an-example-from-quantecon-jl-to-pomdps-jl/16377)

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**Author:** [@amrods](https://discourse.julialang.org/u/amrods)\
**Replies:** 1\
**Last updated:** [November 21, 2019, 8:23pm UTC](https://discourse.julialang.org/t/porting-an-example-from-quantecon-jl-to-pomdps-jl/16377 "2019-11-21T20:23:22Z")

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Just for fun (and to learn about POMDP) I am porting an example of dynamic programming from QuantEcon.jl to POMDPs.jl. The example is available here: https://lectures.quantecon.org/jl/discrete\_dp.html#example-a-growth-mo…

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## [StatsPlots, precompiling error](https://discourse.julialang.org/t/statsplots-precompiling-error/31354)

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**Author:** [@Gunter\_Faes](https://discourse.julialang.org/u/Gunter_Faes)\
**Replies:** 0\
**Last updated:** [November 21, 2019, 7:20pm UTC](https://discourse.julialang.org/t/statsplots-precompiling-error/31354 "2019-11-21T19:20:43Z")

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Hi, I am currently experimenting with my nVIDIA Jetson Nano and have had no problems so far. Now I want to use StatsPlots in addition to PLots, but for StastPlots it is noted in the precompiling phase that the Arpack pa…

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## [Gradient of a Hessian dependent loss function](https://discourse.julialang.org/t/gradient-of-a-hessian-dependent-loss-function/31322)

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**Author:** [@mtgd](https://discourse.julialang.org/u/mtgd)\
**Replies:** 1\
**Last updated:** [November 21, 2019, 6:35pm UTC](https://discourse.julialang.org/t/gradient-of-a-hessian-dependent-loss-function/31322 "2019-11-21T18:35:38Z")

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For my application it would be useful to have a loss function that depends on the Hessian of a model. Computing the Hessian with respect to the input variable (using Tracker) works fine, but trying to get the gradient w…

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## [Anyone using a PAID source for Sp500 options data specifically 30 day mean implied volatility?](https://discourse.julialang.org/t/anyone-using-a-paid-source-for-sp500-options-data-specifically-30-day-mean-implied-volatility/31324)

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**Author:** [@anon97116444](https://discourse.julialang.org/u/anon97116444)\
**Replies:** 8\
**Last updated:** [November 21, 2019, 2:24pm UTC](https://discourse.julialang.org/t/anyone-using-a-paid-source-for-sp500-options-data-specifically-30-day-mean-implied-volatility/31324 "2019-11-21T14:24:24Z")

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I can’t seem to find any discussion on discourse about live options data? I’m looking for the following. date,time,symbol,last,volume, open interest, 30 day mean implied volatility. don’t need HFT just 1 - 5 minutes w…

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## [Trignometric functions on GPU](https://discourse.julialang.org/t/trignometric-functions-on-gpu/31338)

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**Author:** [@ennvvy](https://discourse.julialang.org/u/ennvvy)\
**Replies:** 4\
**Last updated:** [November 21, 2019, 8:55am UTC](https://discourse.julialang.org/t/trignometric-functions-on-gpu/31338 "2019-11-21T08:55:17Z")

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I tried executing a simple function involving sin and cos as below: using CUDAdrv,CUDAnative,CuArrays sine(x::Float32) = sin(x) cosine(x::Float32) = cos(x) CuArrays.@cufunc sine(x::Real) = sin(x) CuArrays.@cufunc cosin…

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## [CuArrays: Call reclaim from user code](https://discourse.julialang.org/t/cuarrays-call-reclaim-from-user-code/31224)

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**Author:** [@DrChainsaw](https://discourse.julialang.org/u/DrChainsaw)\
**Replies:** 4\
**Last updated:** [November 20, 2019, 7:14pm UTC](https://discourse.julialang.org/t/cuarrays-call-reclaim-from-user-code/31224 "2019-11-20T19:14:47Z")

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Hi, I’m getting hit pretty hard with what I think is this issue: https://github.com/JuliaGPU/CuArrays.jl/issues/323 When using CuArrays 1.2.1 I could keep things afloat fairly well by calling CuArrays.reclaim(true) at …

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## [Code for Ticks Control with Vegalite.jl](https://discourse.julialang.org/t/code-for-ticks-control-with-vegalite-jl/31134)

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**Author:** [@Usor](https://discourse.julialang.org/u/Usor)\
**Replies:** 9\
**Last updated:** [November 20, 2019, 1:01pm UTC](https://discourse.julialang.org/t/code-for-ticks-control-with-vegalite-jl/31134 "2019-11-20T13:01:08Z")

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I tried before, searched the Vegalite.jl documentation, searched the original Vegalite documentation (and tried to convert some code), considered somewhat directly using JSON-like code, and didn’t succeed in this matter.…

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## [The performance difference of transferring (SubArray, ReshapedArray) Array to GPU](https://discourse.julialang.org/t/the-performance-difference-of-transferring-subarray-reshapedarray-array-to-gpu/31303)

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**Author:** [@findmyway](https://discourse.julialang.org/u/findmyway)\
**Replies:** 2\
**Last updated:** [November 20, 2019, 8:50am UTC](https://discourse.julialang.org/t/the-performance-difference-of-transferring-subarray-reshapedarray-array-to-gpu/31303 "2019-11-20T08:50:29Z")

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I encounter some performance differences when trying to move data from cpu to gpu. The result is listed in the table bellow: methods cpu(x) gpu(x) CuArray{Float32}(x) a = rand(Float32, 100, 100, 32); 62.947 ns (…

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## [Does ScikitLearn support sample weights for scikit-learn models that do?](https://discourse.julialang.org/t/does-scikitlearn-support-sample-weights-for-scikit-learn-models-that-do/30815)

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**Author:** [@ablaom](https://discourse.julialang.org/u/ablaom)\
**Replies:** 1\
**Last updated:** [November 19, 2019, 10:29pm UTC](https://discourse.julialang.org/t/does-scikitlearn-support-sample-weights-for-scikit-learn-models-that-do/30815 "2019-11-19T22:29:42Z")

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In the python scikit-learn the linear model SGDRegressor, and others, support sample weights for training. I could not guess how to access this through the ScikitLearn.jl interface. Is this not supported? using ScikitLe…

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## [Benchmarking a simple PDE algorithm in Julia, Python, Matlab, C++, and Fortran](https://discourse.julialang.org/t/benchmarking-a-simple-pde-algorithm-in-julia-python-matlab-c-and-fortran/5002)

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**Author:** [@John\_Gibson](https://discourse.julialang.org/u/John_Gibson)\
**Replies:** 41\
**Last updated:** [November 19, 2019, 10:12pm UTC](https://discourse.julialang.org/t/benchmarking-a-simple-pde-algorithm-in-julia-python-matlab-c-and-fortran/5002 "2019-11-19T22:12:23Z")

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As a warm-up and preliminary test for writing a distributed-memory fluids code in Julia, I did some benchmarking of Julia on a simple numerical integration algorithm for the 1d Kuramoto-Sivashinky equation. https://gith…

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## [Help implementing Tables.jl interface](https://discourse.julialang.org/t/help-implementing-tables-jl-interface/31277)

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**Author:** [@randyzwitch](https://discourse.julialang.org/u/randyzwitch)\
**Replies:** 5\
**Last updated:** [November 19, 2019, 4:20pm UTC](https://discourse.julialang.org/t/help-implementing-tables-jl-interface/31277 "2019-11-19T16:20:49Z")

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PR with code here: https://github.com/omnisci/OmniSci.jl/pull/88/files I’m looking to modify some functions that take DataFrames as arguments to be more generic to take Tables, but I’m still not sure I understand why Ta…

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## [Mark size in axis units with PGFPlotsX](https://discourse.julialang.org/t/mark-size-in-axis-units-with-pgfplotsx/31266)

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**Author:** [@danscr](https://discourse.julialang.org/u/danscr)\
**Replies:** 7\
**Last updated:** [November 19, 2019, 12:54pm UTC](https://discourse.julialang.org/t/mark-size-in-axis-units-with-pgfplotsx/31266 "2019-11-19T12:54:11Z")

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I want to plot a 3d array as a voxel grid (i.e. adjacent cubes of equal size) with PGFPlotsX. So far I got a simple solution using a 3d scatterplot with filled cubes of separate color, depending on the array value. The…

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## [Using ForwardDiff to compute the jacobian and gradient of a function that includes another function](https://discourse.julialang.org/t/using-forwarddiff-to-compute-the-jacobian-and-gradient-of-a-function-that-includes-another-function/31255)

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**Author:** [@Ujku\_KU](https://discourse.julialang.org/u/Ujku_KU)\
**Replies:** 0\
**Last updated:** [November 19, 2019, 7:35am UTC](https://discourse.julialang.org/t/using-forwarddiff-to-compute-the-jacobian-and-gradient-of-a-function-that-includes-another-function/31255 "2019-11-19T07:35:29Z")

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hi guys I have a situation like following: function update\_step(kernelPCA::KernelPCA, withRespectTo::Type{WithRespectToData}, abstractApplication::Type{Denoising}, …

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## [Which tools to do a chromaticity diagram?](https://discourse.julialang.org/t/which-tools-to-do-a-chromaticity-diagram/31230)

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**Author:** [@klaff](https://discourse.julialang.org/u/klaff)\
**Replies:** 4\
**Last updated:** [November 18, 2019, 10:05pm UTC](https://discourse.julialang.org/t/which-tools-to-do-a-chromaticity-diagram/31230 "2019-11-18T22:05:49Z")

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I want to make some chromaticity diagrams (e.g.Chromaticity - Wikipedia) and am not sure which Julia graphics package would be most suitable. I’ve been looking at Luxor, Plots, Makie, and Gadfly examples and am leaning t…

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## [Gradient of parameters that apply only to subsets of data](https://discourse.julialang.org/t/gradient-of-parameters-that-apply-only-to-subsets-of-data/31181)

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**Author:** [@mihai](https://discourse.julialang.org/u/mihai)\
**Replies:** 3\
**Last updated:** [November 18, 2019, 8:09pm UTC](https://discourse.julialang.org/t/gradient-of-parameters-that-apply-only-to-subsets-of-data/31181 "2019-11-18T20:09:09Z")

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Hi, I would like to optimize parameters of an analytic function to fit heterogeneous data (different experimental conditions, partly overlapping). I’m using index arrays to know which parameters to use for which data poi…

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## [JuMP : not getting the correct solution of the optimization problem](https://discourse.julialang.org/t/jump-not-getting-the-correct-solution-of-the-optimization-problem/29947)

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**Author:** [@Val](https://discourse.julialang.org/u/Val)\
**Replies:** 7\
**Last updated:** [October 16, 2019, 3:23pm UTC](https://discourse.julialang.org/t/jump-not-getting-the-correct-solution-of-the-optimization-problem/29947 "2019-10-16T15:23:28Z")

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Dear everyone I am solving a minimization problem under equality and inequality constraints. I solve this problem with COSMO and I get a solution which is the vector alpha\_opt=\[0 0 0\] But I found another vector which i…

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## [Setting up environment to debug a network protocol](https://discourse.julialang.org/t/setting-up-environment-to-debug-a-network-protocol/31138)

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**Author:** [@Janis\_Erdmanis](https://discourse.julialang.org/u/Janis_Erdmanis)\
**Replies:** 1\
**Last updated:** [November 17, 2019, 9:53am UTC](https://discourse.julialang.org/t/setting-up-environment-to-debug-a-network-protocol/31138 "2019-11-17T09:53:28Z")

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Hello, everyone! I am writing a package for a little bit involved network protocol which I have outlined here (some details like the use of TOR and ballot key had become obsolete). An essential part of the protocol is t…

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## [Style guide: in or =](https://discourse.julialang.org/t/style-guide-in-or/31155)

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**Author:** [@remi-garcia](https://discourse.julialang.org/u/remi-garcia)\
**Replies:** 2\
**Last updated:** [November 17, 2019, 7:58am UTC](https://discourse.julialang.org/t/style-guide-in-or/31155 "2019-11-17T07:58:30Z")

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Hi, JuMP’ style guide states we should prefer in over = in for loops: Style Guide · JuMP I was wondering why it is not the same for variables and constraints declaration as in the documentation we can find @variable(mo…

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## [How compute \`gradient.(f, w)\` on GPU?](https://discourse.julialang.org/t/how-compute-gradient-f-w-on-gpu/30916)

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**Author:** [@xiaodai](https://discourse.julialang.org/u/xiaodai)\
**Replies:** 2\
**Last updated:** [November 16, 2019, 8:06am UTC](https://discourse.julialang.org/t/how-compute-gradient-f-w-on-gpu/30916 "2019-11-16T08:06:57Z")

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I can’t seem to figure out how to use the CuArray to compute the gradient of the same function f at many points x. E.g. using Zygote:gradient f(x) = x^2 x = rand(100) gradient.(f, x) the above works fine becuase it’s…

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## [This custom Zygote.jl adjoint is not giving me the speed up I expected and how to migrate to GPU?](https://discourse.julialang.org/t/this-custom-zygote-jl-adjoint-is-not-giving-me-the-speed-up-i-expected-and-how-to-migrate-to-gpu/31150)

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**Author:** [@xiaodai](https://discourse.julialang.org/u/xiaodai)\
**Replies:** 0\
**Last updated:** [November 16, 2019, 8:01am UTC](https://discourse.julialang.org/t/this-custom-zygote-jl-adjoint-is-not-giving-me-the-speed-up-i-expected-and-how-to-migrate-to-gpu/31150 "2019-11-16T08:01:50Z")

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I tried to use Zygote.jl to define a custom adjoint for Flux.logitbinarycrossentropy but I don’t get the expected speed up when computing the gradient. The context is that the XGBoost tree boosting algorithm requires tak…

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## [How to get the gradient of NN wr to its input?](https://discourse.julialang.org/t/how-to-get-the-gradient-of-nn-wr-to-its-input/31034)

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**Author:** [@HenriDeh](https://discourse.julialang.org/u/HenriDeh)\
**Replies:** 6\
**Last updated:** [November 15, 2019, 5:16pm UTC](https://discourse.julialang.org/t/how-to-get-the-gradient-of-nn-wr-to-its-input/31034 "2019-11-15T17:16:49Z")

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Why do I get this error with this MWE ? nn= Dense(5,1) static\_input = \[1,2,3,4\] variable\_input = 5 opt = Nesterov() ps = Flux.Params(variable\_input) g = Flux.gradient(ps) do sum(nn(vcat(static\_input, variable\_input)…

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## [Has anyone implemented slopecharts/slopegraphs/bump charts in Julia yet?](https://discourse.julialang.org/t/has-anyone-implemented-slopecharts-slopegraphs-bump-charts-in-julia-yet/31107)

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**Author:** [@anon97116444](https://discourse.julialang.org/u/anon97116444)\
**Replies:** 7\
**Last updated:** [November 15, 2019, 5:10pm UTC](https://discourse.julialang.org/t/has-anyone-implemented-slopecharts-slopegraphs-bump-charts-in-julia-yet/31107 "2019-11-15T17:10:15Z")

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Hi all not started with Julia YET but will do so next week. I would like to know if there is a mechanism for implementing SLOPEGRAPHS ( sometimes called bump charts) in Julia? This is an article on the form of the char…

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## [How to set the seed properly in CURAND](https://discourse.julialang.org/t/how-to-set-the-seed-properly-in-curand/24180)

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**Author:** [@findmyway](https://discourse.julialang.org/u/findmyway)\
**Replies:** 4\
**Last updated:** [November 15, 2019, 4:04pm UTC](https://discourse.julialang.org/t/how-to-set-the-seed-properly-in-curand/24180 "2019-11-15T16:04:49Z")

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I just found it’s a little tricky for me to set the seed in CuArrays.CURAND julia\> using CuArrays, CuArrays.CURAND julia\> s = CuArrays.CURAND.create\_generator() CuArrays.CURAND.RNG(Ptr{Nothing} @0x00000000054faec0, 100…

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## [Problem of binarycrossentropy with GPU?](https://discourse.julialang.org/t/problem-of-binarycrossentropy-with-gpu/31026)

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**Author:** [@taot](https://discourse.julialang.org/u/taot)\
**Replies:** 2\
**Last updated:** [November 15, 2019, 9:49am UTC](https://discourse.julialang.org/t/problem-of-binarycrossentropy-with-gpu/31026 "2019-11-15T09:49:41Z")

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Hi, I am trying to create a model in Flux, with binarycrossentropy in loss function, but encountered a problem invoking binarycrossentropy on GPU. I reproduced the error with this simple case: # just copy from document…

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