# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=465

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**Page:** 466

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## [Julia alternative for turtle graphics](https://discourse.julialang.org/t/julia-alternative-for-turtle-graphics/31683)

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**Author:** [@chakravala](https://discourse.julialang.org/u/chakravala)\
**Replies:** 8\
**Last updated:** [January 31, 2020, 10:56pm UTC](https://discourse.julialang.org/t/julia-alternative-for-turtle-graphics/31683 "2020-01-31T22:56:12Z")

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A while back I made a nice visualization of the Ramanujan tau function using python turtle graphics, which I made for the 100th anniversary of this function. The turtle interface was very nice for making the graphics, wh…

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## [Sample conditional multivariate random variable?](https://discourse.julialang.org/t/sample-conditional-multivariate-random-variable/34035)

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**Author:** [@Alex1](https://discourse.julialang.org/u/Alex1)\
**Replies:** 4\
**Last updated:** [January 31, 2020, 10:40pm UTC](https://discourse.julialang.org/t/sample-conditional-multivariate-random-variable/34035 "2020-01-31T22:40:03Z")

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There’s multivariate random variable, future prices of assets, 5 years from now: X = \[Gold, Silver, SP500\] There’s historical prices for X available for last 50 years. It’s possible to fit historical prices to get mult…

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## [\[JuMP\] Use ConstraintRef to add additional constraint](https://discourse.julialang.org/t/jump-use-constraintref-to-add-additional-constraint/34046)

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**Author:** [@acauligi](https://discourse.julialang.org/u/acauligi)\
**Replies:** 1\
**Last updated:** [January 31, 2020, 8:09pm UTC](https://discourse.julialang.org/t/jump-use-constraintref-to-add-additional-constraint/34046 "2020-01-31T20:09:07Z")

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Hi, I have an affine inequality constraint in a JuMP model (that was constructed off-line) and would like to add a new constraint using the expression from the ConstraintRef associated with the affine constraint. e.g.: …

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## [What does and does-not get computed on the GPU? (CuArrays)](https://discourse.julialang.org/t/what-does-and-does-not-get-computed-on-the-gpu-cuarrays/34042)

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**Author:** [@jaynick](https://discourse.julialang.org/u/jaynick)\
**Replies:** 1\
**Last updated:** [January 31, 2020, 6:41pm UTC](https://discourse.julialang.org/t/what-does-and-does-not-get-computed-on-the-gpu-cuarrays/34042 "2020-01-31T18:41:26Z")

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Is there a easy explanation or “rule of thumb” about which computations are run on the GPU? For example, if there is a matrix ‘W’ and array ‘a’, both on the gpu, I am sure that W\*a is computed on the GPU. But what abou…

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## [\[Convex.jl\] Suppress warnings when printing problem tree](https://discourse.julialang.org/t/convex-jl-suppress-warnings-when-printing-problem-tree/34029)

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**Author:** [@4aHxKzD](https://discourse.julialang.org/u/4aHxKzD)\
**Replies:** 2\
**Last updated:** [January 31, 2020, 3:22pm UTC](https://discourse.julialang.org/t/convex-jl-suppress-warnings-when-printing-problem-tree/34029 "2020-01-31T15:22:48Z")

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Is there a way to suppress warnings such as Warning: Expression not DCP compliant. when printing the problem tree?

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## [Help with gradient](https://discourse.julialang.org/t/help-with-gradient/33943)

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**Author:** [@ccc1685](https://discourse.julialang.org/u/ccc1685)\
**Replies:** 6\
**Last updated:** [January 31, 2020, 1:31pm UTC](https://discourse.julialang.org/t/help-with-gradient/33943 "2020-01-31T13:31:10Z")

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Hi, I have a loss function that involves a probability density that requires several matrix operations to derive. When I tried running gradient on it through either Flux or Zygote I get this error: Mutating arrays is n…

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## [Way to train model in Julia and deploy in Javascript?](https://discourse.julialang.org/t/way-to-train-model-in-julia-and-deploy-in-javascript/34002)

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**Author:** [@djsegal](https://discourse.julialang.org/u/djsegal)\
**Replies:** 0\
**Last updated:** [January 30, 2020, 11:53pm UTC](https://discourse.julialang.org/t/way-to-train-model-in-julia-and-deploy-in-javascript/34002 "2020-01-30T23:53:43Z")

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I recently built an Airbnb price prediction tool in Javascript. However I had to do a lot of my initial work and EDA in Python using Scikit-learn. This seemed like a two language problem, so was wondering if anyone had …

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## [IFFT Scaling](https://discourse.julialang.org/t/ifft-scaling/33979)

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**Author:** [@jleman](https://discourse.julialang.org/u/jleman)\
**Replies:** 5\
**Last updated:** [January 30, 2020, 9:25pm UTC](https://discourse.julialang.org/t/ifft-scaling/33979 "2020-01-30T21:25:38Z")

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Does anyone know if there is a 1/N or 1/sqrt(N) scaling in the IFFT function of FFTW.jl? I am taking the IFFT of an array of complex numbers sampled from a continuous frequency domain function. The resulting time domai…

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## [Equivalent of list() (R) in Julia](https://discourse.julialang.org/t/equivalent-of-list-r-in-julia/2860)

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**Author:** [@Jonathan\_Droxler](https://discourse.julialang.org/u/Jonathan_Droxler)\
**Replies:** 19\
**Last updated:** [January 30, 2020, 8:54pm UTC](https://discourse.julialang.org/t/equivalent-of-list-r-in-julia/2860 "2020-01-30T20:54:31Z")

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Dear all, Quite new in Julia (I’m already a big fan), I was wondering if there exist any data structure in Julia like “list()” in R. I search in the documentation, on google. Maybe I didn’t search well but I didn’t find…

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## [Wrapping Python PyViz Graphics Libraries](https://discourse.julialang.org/t/wrapping-python-pyviz-graphics-libraries/33997)

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**Author:** [@ea42gh](https://discourse.julialang.org/u/ea42gh)\
**Replies:** 0\
**Last updated:** [January 30, 2020, 8:15pm UTC](https://discourse.julialang.org/t/wrapping-python-pyviz-graphics-libraries/33997 "2020-01-30T20:15:07Z")

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What would be a good starting point to read to figure out how to wrap python graph libraries http://holoviews.org/ and Panel Documentation — Panel v0.13.1 ? Has somebody already attempted it?

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## [How do you create a transparent .png using Images.jl?](https://discourse.julialang.org/t/how-do-you-create-a-transparent-png-using-images-jl/33981)

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**Author:** [@NiclasMattsson](https://discourse.julialang.org/u/NiclasMattsson)\
**Replies:** 3\
**Last updated:** [January 30, 2020, 6:51pm UTC](https://discourse.julialang.org/t/how-do-you-create-a-transparent-png-using-images-jl/33981 "2020-01-30T18:51:15Z")

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The following does not work. In Photoshop terms, it creates a .png with a (solid black) background layer instead of an ordinary layer, and background layers cannot have transparent pixels. julia\> using Images julia\> im…

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## [Use Sign Function in JuMP NLconstraint](https://discourse.julialang.org/t/use-sign-function-in-jump-nlconstraint/33973)

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**Author:** [@cupcc](https://discourse.julialang.org/u/cupcc)\
**Replies:** 2\
**Last updated:** [January 30, 2020, 2:15pm UTC](https://discourse.julialang.org/t/use-sign-function-in-jump-nlconstraint/33973 "2020-01-30T14:15:06Z")

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I’m currently trying to solve a problem in JuMP that has a nonlinear constraint that has the form y= (other expressions) + constant \* sign(x). This throws an error saying sign is not a recognized function. How do I fix …

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## [Importing Pre-Trained Model in Julia](https://discourse.julialang.org/t/importing-pre-trained-model-in-julia/33952)

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**Author:** [@abianco](https://discourse.julialang.org/u/abianco)\
**Replies:** 2\
**Last updated:** [January 30, 2020, 12:05pm UTC](https://discourse.julialang.org/t/importing-pre-trained-model-in-julia/33952 "2020-01-30T12:05:14Z")

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Is there an effective way to import a pre-trained model (or at least the model specification and weights) in Julia and use it in TensorFlow.jl? If not, are there other ways to load in a pre-trained BLSTM and work with i…

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## [Ayush1999's Keras.jl on Julia 1.3.1 precompiling failure](https://discourse.julialang.org/t/ayush1999s-keras-jl-on-julia-1-3-1-precompiling-failure/33951)

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**Author:** [@abianco](https://discourse.julialang.org/u/abianco)\
**Replies:** 10\
**Last updated:** [January 30, 2020, 3:31am UTC](https://discourse.julialang.org/t/ayush1999s-keras-jl-on-julia-1-3-1-precompiling-failure/33951 "2020-01-30T03:31:21Z")

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I see that the package is a bit stale and has not been upgraded to work on Julia 1, however I was able to install it seamlessly in Julia 1.3.1 by executing Pkg.add(Pkg.PackageSpec(url="https://github.com/ayush1999/Keras.…

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## [How to force using Tracker (not Zygote) in Flux 0.10](https://discourse.julialang.org/t/how-to-force-using-tracker-not-zygote-in-flux-0-10/33916)

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**Author:** [@jaynick](https://discourse.julialang.org/u/jaynick)\
**Replies:** 1\
**Last updated:** [January 29, 2020, 2:28pm UTC](https://discourse.julialang.org/t/how-to-force-using-tracker-not-zygote-in-flux-0-10/33916 "2020-01-29T14:28:56Z")

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I want to try this for debugging. In fact one of the Flux example codes does not even run under 0.10.1, error mutating arrays not supported. I tried doing using Tracker before using Flux, however it still gives the erro…

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## [Convert between z critical values and confidence levels?](https://discourse.julialang.org/t/convert-between-z-critical-values-and-confidence-levels/33904)

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**Author:** [@Usor](https://discourse.julialang.org/u/Usor)\
**Replies:** 1\
**Last updated:** [January 29, 2020, 5:23am UTC](https://discourse.julialang.org/t/convert-between-z-critical-values-and-confidence-levels/33904 "2020-01-29T05:23:57Z")

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Are there readily available functions to immediately convert between these two?

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## [How to save additional data in or with a solution when using DifferentialEquations](https://discourse.julialang.org/t/how-to-save-additional-data-in-or-with-a-solution-when-using-differentialequations/33892)

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**Author:** [@klaff](https://discourse.julialang.org/u/klaff)\
**Replies:** 2\
**Last updated:** [January 29, 2020, 2:41am UTC](https://discourse.julialang.org/t/how-to-save-additional-data-in-or-with-a-solution-when-using-differentialequations/33892 "2020-01-29T02:41:58Z")

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Is there an idiom for saving non-state variables in or with the solution? I would like to be able to list additional variables (either intermediate ones that I calculate anyway or derived ones of interest) and have them…

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## [Computer freezes with parallel](https://discourse.julialang.org/t/computer-freezes-with-parallel/33903)

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**Author:** [@squirrel](https://discourse.julialang.org/u/squirrel)\
**Replies:** 0\
**Last updated:** [January 28, 2020, 8:13pm UTC](https://discourse.julialang.org/t/computer-freezes-with-parallel/33903 "2020-01-28T20:13:18Z")

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Hi. I need to use parallel programming and I’ve been trying to play around with some basic parts. When I try to benchmark a simple threaded function, my laptop freezes for over five minutes and I resort to doing a hard s…

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## [Renaming IDs in a GFF3](https://discourse.julialang.org/t/renaming-ids-in-a-gff3/33687)

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**Author:** [@mictadlo](https://discourse.julialang.org/u/mictadlo)\
**Replies:** 42\
**Last updated:** [January 28, 2020, 3:51pm UTC](https://discourse.julialang.org/t/renaming-ids-in-a-gff3/33687 "2020-01-28T15:51:28Z")

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Hi, are there any examples of renaming IDs in a GFF3 file? Thank you in advance,

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## [AD in a SGD loop: one call to 'gradient' or many?](https://discourse.julialang.org/t/ad-in-a-sgd-loop-one-call-to-gradient-or-many/33793)

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**Author:** [@jaynick](https://discourse.julialang.org/u/jaynick)\
**Replies:** 5\
**Last updated:** [January 27, 2020, 6:09pm UTC](https://discourse.julialang.org/t/ad-in-a-sgd-loop-one-call-to-gradient-or-many/33793 "2020-01-27T18:09:21Z")

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A general question about how to think about automatic differentiation. I might have thought the gradient is a function, that takes in a location and returns the up-hill vector at that location. If an AD returned such a…

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## [Use the old Tracker interface in Flux 0.10?](https://discourse.julialang.org/t/use-the-old-tracker-interface-in-flux-0-10/33820)

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**Author:** [@jaynick](https://discourse.julialang.org/u/jaynick)\
**Replies:** 3\
**Last updated:** [January 27, 2020, 6:04pm UTC](https://discourse.julialang.org/t/use-the-old-tracker-interface-in-flux-0-10/33820 "2020-01-27T18:04:57Z")

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Flux 0.10 provides Zygote as the AD. Is it still possible to use Tracker in this (and near future) version of Flux? If so, wondering if it would be possible to program a unified api wrapper that would call either with …

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## [Fix contour colors scale](https://discourse.julialang.org/t/fix-contour-colors-scale/33767)

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**Author:** [@pedrohnv](https://discourse.julialang.org/u/pedrohnv)\
**Replies:** 2\
**Last updated:** [January 27, 2020, 5:38pm UTC](https://discourse.julialang.org/t/fix-contour-colors-scale/33767 "2020-01-27T17:38:52Z")

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Hello, I would like to show an animation of a contour plot. For better visualization, it would be ideal if I could fix the colorbar in addition to the levels. Example: using Plots anim = @animate for i=0:10 …

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## [Current status with callbacks](https://discourse.julialang.org/t/current-status-with-callbacks/29942)

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**Author:** [@Lefteris\_Manousakis](https://discourse.julialang.org/u/Lefteris_Manousakis)\
**Replies:** 6\
**Last updated:** [January 27, 2020, 3:52pm UTC](https://discourse.julialang.org/t/current-status-with-callbacks/29942 "2020-01-27T15:52:00Z")

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Hi everyone! I am using JuMP 0.19 and I tried to set up an information callback to retrieve the relaxation value of the root node. After a lot of searching I think I got the picture with the non solver independent callb…

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## [Can't differentiate loopinfo expression when trying to compute second order derivatives using Flux and Distributions](https://discourse.julialang.org/t/cant-differentiate-loopinfo-expression-when-trying-to-compute-second-order-derivatives-using-flux-and-distributions/33818)

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**Author:** [@hsm207](https://discourse.julialang.org/u/hsm207)\
**Replies:** 0\
**Last updated:** [January 26, 2020, 7:14pm UTC](https://discourse.julialang.org/t/cant-differentiate-loopinfo-expression-when-trying-to-compute-second-order-derivatives-using-flux-and-distributions/33818 "2020-01-26T19:14:34Z")

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I am trying to compute the maximum a posterior (MAP) estimate and want to get the hessian of the log likelihood too. This is what I have tried with respect to computing the Hessian: using Flux, Distributions prior\_mean…

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## [Local thread memory in GPU using StaticArrays](https://discourse.julialang.org/t/local-thread-memory-in-gpu-using-staticarrays/33761)

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**Author:** [@alvrg](https://discourse.julialang.org/u/alvrg)\
**Replies:** 4\
**Last updated:** [January 26, 2020, 11:25pm UTC](https://discourse.julialang.org/t/local-thread-memory-in-gpu-using-staticarrays/33761 "2020-01-26T23:25:20Z")

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Hi all, I want to write a CUDA kernel that uses some local memory per thread. I read here and here that a possible way to do it is using StaticArrays, but I couldn’t find a MWE of this. The code I want to run is this, …

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## [The second edition of my book "Julia Programming for Operations Research"](https://discourse.julialang.org/t/the-second-edition-of-my-book-julia-programming-for-operations-research/21262)

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**Author:** [@chkwon](https://discourse.julialang.org/u/chkwon)\
**Replies:** 8\
**Last updated:** [January 26, 2020, 1:07am UTC](https://discourse.julialang.org/t/the-second-edition-of-my-book-julia-programming-for-operations-research/21262 "2020-01-26T01:07:55Z")

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Dear friends, Long waited JuMP v0.19 is now released and I updated my book accordingly. Here is the second edition of my book “Julia Programming for Operations Research” available online. Ten free copies for discourse …

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## [FFT + Measurements](https://discourse.julialang.org/t/fft-measurements/33791)

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**Author:** [@feanor12](https://discourse.julialang.org/u/feanor12)\
**Replies:** 1\
**Last updated:** [January 26, 2020, 12:31am UTC](https://discourse.julialang.org/t/fft-measurements/33791 "2020-01-26T00:31:39Z")

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I thought it would be cool if I could calculate the FFT using uncertain data, so I tried using Measurements together with FFTW. I did not get it working. Instead, I wrote a simple FT function which can be used with Meas…

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## [Automatic Differentiation of arbitrary-order derivatives](https://discourse.julialang.org/t/automatic-differentiation-of-arbitrary-order-derivatives/33774)

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**Author:** [@GregVernon](https://discourse.julialang.org/u/GregVernon)\
**Replies:** 3\
**Last updated:** [January 25, 2020, 9:36am UTC](https://discourse.julialang.org/t/automatic-differentiation-of-arbitrary-order-derivatives/33774 "2020-01-25T09:36:16Z")

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I was wondering if it is possible to programmatically do higher-order automatic differentiation using ForwardDiff (or ReverseDiff). Here’s a MWE that shows a non-optimal way to get specific derivatives (hard-coded): im…

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## [Interactive Vegalite in Jupyter lab](https://discourse.julialang.org/t/interactive-vegalite-in-jupyter-lab/33771)

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**Author:** [@darwindarak](https://discourse.julialang.org/u/darwindarak)\
**Replies:** 2\
**Last updated:** [January 25, 2020, 2:48am UTC](https://discourse.julialang.org/t/interactive-vegalite-in-jupyter-lab/33771 "2020-01-25T02:48:52Z")

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Hi all, I’m having some problems getting interactive plots (simple tooltip) to show up inline in a notebook. The docs say that Jupyter lab should already have the capability, but I can only get it to work if I save the …

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## [VAE in Flux model zoo](https://discourse.julialang.org/t/vae-in-flux-model-zoo/33747)

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**Author:** [@rsteckel](https://discourse.julialang.org/u/rsteckel)\
**Replies:** 0\
**Last updated:** [January 24, 2020, 2:10pm UTC](https://discourse.julialang.org/t/vae-in-flux-model-zoo/33747 "2020-01-24T14:10:44Z")

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I’ve been unable to get the MNIST VAE example in Flux’s model zoo to train. During epoch 1 of training, I get this error: \[ Info: Epoch 1 ERROR: Mutating arrays is not supported Stacktrace: \[1\] (::Zygote.var"#1003#100…

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