# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?page=469

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**Page:** 470

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## [How to change the type of a variable for a loaded table?](https://discourse.julialang.org/t/how-to-change-the-type-of-a-variable-for-a-loaded-table/32973)

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**Author:** [@kai](https://discourse.julialang.org/u/kai)\
**Replies:** 11\
**Last updated:** [January 6, 2020, 9:34pm UTC](https://discourse.julialang.org/t/how-to-change-the-type-of-a-variable-for-a-loaded-table/32973 "2020-01-06T21:34:36Z")

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I’m trying to use JuliaDB to load tables and then use MixedModels to fit models. The MixedModels package requires the clustering variable “id” to be categorical, but in my dataset “id” is integer. So my question is, ho…

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## [sIpopt extension in JuMP?](https://discourse.julialang.org/t/sipopt-extension-in-jump/32899)

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**Author:** [@mandart](https://discourse.julialang.org/u/mandart)\
**Replies:** 6\
**Last updated:** [January 6, 2020, 9:29pm UTC](https://discourse.julialang.org/t/sipopt-extension-in-jump/32899 "2020-01-06T21:29:05Z")

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Hi, is there a way to use the sIpopt extension to Ipopt (https://projects.coin-or.org/Ipopt/wiki/sIpopt) within JuMP? I can set up a JuMP model with a call to the AMPL sIpopt executable using AmplNLWriter.jl. However, s…

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## [How to drop the dropout layers in Flux.jl when assessing model performance](https://discourse.julialang.org/t/how-to-drop-the-dropout-layers-in-flux-jl-when-assessing-model-performance/19924)

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**Author:** [@xiaodai](https://discourse.julialang.org/u/xiaodai)\
**Replies:** 2\
**Last updated:** [January 6, 2020, 5:59pm UTC](https://discourse.julialang.org/t/how-to-drop-the-dropout-layers-in-flux-jl-when-assessing-model-performance/19924 "2020-01-06T17:59:54Z")

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I was playing around with the Flux.jl framework and I fitted a model with dropouts at every layer. using Flux, Flux.Data.MNIST, Statistics using Flux: onehotbatch, onecold, crossentropy, throttle using Base.Iterators: r…

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## [Fortuna random number generator](https://discourse.julialang.org/t/fortuna-random-number-generator/33030)

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**Author:** [@mleisher](https://discourse.julialang.org/u/mleisher)\
**Replies:** 2\
**Last updated:** [January 6, 2020, 5:28pm UTC](https://discourse.julialang.org/t/fortuna-random-number-generator/33030 "2020-01-06T17:28:15Z")

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I whipped up a Fortuna RNG (generator only, no entropy accumulator and seed file yet) and being fairly new to Julia, am looking for performance improvement suggestions. New feature suggestions are welcome as well, but th…

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## [Optimization problem](https://discourse.julialang.org/t/optimization-problem/33026)

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**Author:** [@Caterina\_Cerutti](https://discourse.julialang.org/u/Caterina_Cerutti)\
**Replies:** 1\
**Last updated:** [January 6, 2020, 4:34pm UTC](https://discourse.julialang.org/t/optimization-problem/33026 "2020-01-06T16:34:10Z")

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EXERCISE: A municipalized company must purchase rubbish bins in an area of the city. There are n types of bins on the market, each characterized by a ci cost and a Ki capacity (i = 1, …, n). M collection points have bee…

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## [Use GPU to generate known sparse matrix](https://discourse.julialang.org/t/use-gpu-to-generate-known-sparse-matrix/33023)

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**Author:** [@FujiwaraTakumiEH](https://discourse.julialang.org/u/FujiwaraTakumiEH)\
**Replies:** 2\
**Last updated:** [January 6, 2020, 12:51pm UTC](https://discourse.julialang.org/t/use-gpu-to-generate-known-sparse-matrix/33023 "2020-01-06T12:51:19Z")

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Suppose we have a known matrix A: \\begin{equation} A=\\left\[\\begin{array}{lll} {1} & {0} & {0} \\\\ {0} & {2} & {4} \\\\ {0} & {0} & {3} \\end{array}\\right\] \\end{equation} At this point, I want to express A as a sparse matr…

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## [How does GPU programming work (Knet example)?](https://discourse.julialang.org/t/how-does-gpu-programming-work-knet-example/32841)

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**Author:** [@jaynick](https://discourse.julialang.org/u/jaynick)\
**Replies:** 5\
**Last updated:** [January 6, 2020, 5:37am UTC](https://discourse.julialang.org/t/how-does-gpu-programming-work-knet-example/32841 "2020-01-06T05:37:21Z")

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Can anyone give a high-level summary of how julia and GPU programming work? In what cases can we write julia code and have it run on the GPU, and in what cases will it not work? I am confused. I needed to clean an imag…

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## [Best ways to do hyper-parameter tuning](https://discourse.julialang.org/t/best-ways-to-do-hyper-parameter-tuning/33010)

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**Author:** [@Albert\_Zevelev](https://discourse.julialang.org/u/Albert_Zevelev)\
**Replies:** 3\
**Last updated:** [January 6, 2020, 2:28am UTC](https://discourse.julialang.org/t/best-ways-to-do-hyper-parameter-tuning/33010 "2020-01-06T02:28:30Z")

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I’d like to tune a model in JLBoost (an awesome, all Julia package by @xiaodai builds on XGBoost, LightGBM, & Catboost). using RDatasets, DataFrames, JLBoost, MLJ; d = dataset("MASS", "Boston"); train, test = partition…

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## [Meta-learning in Julia](https://discourse.julialang.org/t/meta-learning-in-julia/32975)

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**Author:** [@hayabu](https://discourse.julialang.org/u/hayabu)\
**Replies:** 3\
**Last updated:** [January 5, 2020, 6:57pm UTC](https://discourse.julialang.org/t/meta-learning-in-julia/32975 "2020-01-05T18:57:30Z")

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Meta learning is a branch of machine learning that deals with learning to learn. An example of this is few-shot learning where the algorithm is trying to learn from a small dataset fast by given example of many datasets …

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## [Does Python and Julia have the same file reading tools?](https://discourse.julialang.org/t/does-python-and-julia-have-the-same-file-reading-tools/29193)

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**Author:** [@Ahmed\_Salih](https://discourse.julialang.org/u/Ahmed_Salih)\
**Replies:** 14\
**Last updated:** [January 4, 2020, 6:52pm UTC](https://discourse.julialang.org/t/does-python-and-julia-have-the-same-file-reading-tools/29193 "2020-01-04T18:52:25Z")

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Hey folks I have spent some time in both Python and Julia to develop the same kind of function, a function which reads some binary files and import its data into an array. I have spent a lot of time tuning the Julia fun…

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## [Vegalite.jl; simple grouped bar chart](https://discourse.julialang.org/t/vegalite-jl-simple-grouped-bar-chart/32702)

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**Author:** [@Usor](https://discourse.julialang.org/u/Usor)\
**Replies:** 5\
**Last updated:** [January 4, 2020, 2:00pm UTC](https://discourse.julialang.org/t/vegalite-jl-simple-grouped-bar-chart/32702 "2020-01-04T14:00:38Z")

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I’ve been fighting with this occasionally, and haven’t gotten it to work. I want to make a simple grouped bar chart out of a simple DataFrame, but no example I’ve seen that just quickly gets to the point. Suppose it’s a…

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## [3D plots -- possible to change view-point?](https://discourse.julialang.org/t/3d-plots-possible-to-change-view-point/10155)

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**Author:** [@BLI](https://discourse.julialang.org/u/BLI)\
**Replies:** 10\
**Last updated:** [January 3, 2020, 11:14pm UTC](https://discourse.julialang.org/t/3d-plots-possible-to-change-view-point/10155 "2020-01-03T23:14:03Z")

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I’m doing a 3D path plot – it looks ok, but I think it would be possible to get a better 3D feeling with a modified view-point (3D plot with time as parameter, starting at turquois and ending in gold…): Question: D…

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## [CUDA\_ERROR\_ILLEGAL\_ADDRESS with CuArrays/Zygote getindex](https://discourse.julialang.org/t/cuda-error-illegal-address-with-cuarrays-zygote-getindex/32744)

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**Author:** [@tanhevg](https://discourse.julialang.org/u/tanhevg)\
**Replies:** 4\
**Last updated:** [January 3, 2020, 12:07pm UTC](https://discourse.julialang.org/t/cuda-error-illegal-address-with-cuarrays-zygote-getindex/32744 "2020-01-03T12:07:56Z")

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Hello, I am getting an error CuError(CUDA\_ERROR\_ILLEGAL\_ADDRESS) with the following stacktrace. My code is trying to take gradients of a deep learning model with Zygote. I wonder if this is a symptom of running out of me…

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## [Package for mathematical functions?](https://discourse.julialang.org/t/package-for-mathematical-functions/32861)

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**Author:** [@juliohm](https://discourse.julialang.org/u/juliohm)\
**Replies:** 12\
**Last updated:** [January 2, 2020, 11:39am UTC](https://discourse.julialang.org/t/package-for-mathematical-functions/32861 "2020-01-02T11:39:15Z")

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Is there a package for manipulating (mathematical) functions? I often find myself manipulating functions in algorithms. For example, I often create the function sum f+g with domain(f+g) = domain(f) ∩ domain(g) such that (…

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## [Complex Uniform Distribution between 1+0im and 2+0im](https://discourse.julialang.org/t/complex-uniform-distribution-between-1-0im-and-2-0im/32831)

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**Author:** [@Amin\_Yahyaabadi](https://discourse.julialang.org/u/Amin_Yahyaabadi)\
**Replies:** 7\
**Last updated:** [January 2, 2020, 9:11am UTC](https://discourse.julialang.org/t/complex-uniform-distribution-between-1-0im-and-2-0im/32831 "2020-01-02T09:11:23Z")

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I am trying to extend Uniform so rand can generate random numbers for Complex types (to test IntelVectorMath library for Complex types) # zeros like syntax function Distributions.Uniform(::Type{T}, a, b) where {T \<: Rea…

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## [DiffEqFlux neural\_ode used with Flux.Train! is slower on GPU than CPU](https://discourse.julialang.org/t/diffeqflux-neural-ode-used-with-flux-train-is-slower-on-gpu-than-cpu/32830)

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**Author:** [@charlie\_strauss](https://discourse.julialang.org/u/charlie_strauss)\
**Replies:** 0\
**Last updated:** [December 31, 2019, 7:47pm UTC](https://discourse.julialang.org/t/diffeqflux-neural-ode-used-with-flux-train-is-slower-on-gpu-than-cpu/32830 "2019-12-31T19:47:45Z")

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\*\*\*It appears Flux training of the DiffEqFlux Package method neural\_ode is incompatible with (fast) GPU operations, But I’m hoping that perhaps I’m doing something wrong and you can point me to example code where gpu op…

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## [Performance issue with broadcasting of custom array wrapper wrapping a CuArray](https://discourse.julialang.org/t/performance-issue-with-broadcasting-of-custom-array-wrapper-wrapping-a-cuarray/32818)

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**Author:** [@Sleort](https://discourse.julialang.org/u/Sleort)\
**Replies:** 5\
**Last updated:** [December 31, 2019, 6:41pm UTC](https://discourse.julialang.org/t/performance-issue-with-broadcasting-of-custom-array-wrapper-wrapping-a-cuarray/32818 "2019-12-31T18:41:39Z")

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Background I’m trying to make my own array (wrapper) type that can be used both on CPUs and GPUs. Here’s a minimal example: struct MyWrapper{T,N,A\<:AbstractArray{T,N}} \<: AbstractArray{T,N} data::A end # Basic Abst…

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## [Running MNIST from model-zoo on Flux v0.10.0/Zygote/GPU](https://discourse.julialang.org/t/running-mnist-from-model-zoo-on-flux-v0-10-0-zygote-gpu/32810)

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**Author:** [@tanhevg](https://discourse.julialang.org/u/tanhevg)\
**Replies:** 2\
**Last updated:** [December 30, 2019, 11:42pm UTC](https://discourse.julialang.org/t/running-mnist-from-model-zoo-on-flux-v0-10-0-zygote-gpu/32810 "2019-12-30T23:42:31Z")

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Hello, I am trying to run the MNIST digit recognition from model-zoo using the latest Flux version with Zygote on a GPU. I had to make some tweaks to the code to make it run: https://github.com/tanhevg/model-zoo/blob/ta…

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## [How to do L2 regularization with new Flux and Zygote](https://discourse.julialang.org/t/how-to-do-l2-regularization-with-new-flux-and-zygote/31756)

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**Author:** [@HenriDeh](https://discourse.julialang.org/u/HenriDeh)\
**Replies:** 2\
**Last updated:** [December 29, 2019, 3:39pm UTC](https://discourse.julialang.org/t/how-to-do-l2-regularization-with-new-flux-and-zygote/31756 "2019-12-29T15:39:31Z")

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I think this MWE used to work. Now I don’t know how to compute a norm penalty because the example in Flux documentation here is still using the old Tracked stuff. using Flux m = Dense(5,1) gs = Flux.gradient(Flux.para…

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## [Interact.jl + Mux.jl + Plots.jl dynamic updating plots memory leak](https://discourse.julialang.org/t/interact-jl-mux-jl-plots-jl-dynamic-updating-plots-memory-leak/22390)

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**Author:** [@jesseventura](https://discourse.julialang.org/u/jesseventura)\
**Replies:** 1\
**Last updated:** [December 28, 2019, 11:26pm UTC](https://discourse.julialang.org/t/interact-jl-mux-jl-plots-jl-dynamic-updating-plots-memory-leak/22390 "2019-12-28T23:26:09Z")

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with scripts running in background, i open a browser and see the plot updating, after i close the browser window, memory starts increasing. gc’s not work(see the code) the following shows the problem with Blink(electro…

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## [How to deploy a secure (\`wss\`) websocket server?](https://discourse.julialang.org/t/how-to-deploy-a-secure-wss-websocket-server/32583)

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**Author:** [@1115](https://discourse.julialang.org/u/1115)\
**Replies:** 1\
**Last updated:** [December 28, 2019, 11:23pm UTC](https://discourse.julialang.org/t/how-to-deploy-a-secure-wss-websocket-server/32583 "2019-12-28T23:23:10Z")

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Hi, I am following this example to setup a websocket service, https://github.com/JuliaWeb/WebSockets.jl/blob/master/examples/minimal\_server.jl This example shows how to handle a URI request like ws://.... However, in …

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## [Encoding categorical variables within a matrix](https://discourse.julialang.org/t/encoding-categorical-variables-within-a-matrix/32628)

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**Author:** [@mthelm85](https://discourse.julialang.org/u/mthelm85)\
**Replies:** 3\
**Last updated:** [December 28, 2019, 1:13am UTC](https://discourse.julialang.org/t/encoding-categorical-variables-within-a-matrix/32628 "2019-12-28T01:13:24Z")

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I have a question about encoding categorical variables when constructing matrices to feed to ML models. Consider this MWE: julia\> rawdata = DataFrame(make=\["honda", "ford", "subaru"\], mpg=\[33,29,31\], price=\[30000,25000…

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## [Sampling from posterior predictive distribution](https://discourse.julialang.org/t/sampling-from-posterior-predictive-distribution/32738)

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**Author:** [@kirtsar](https://discourse.julialang.org/u/kirtsar)\
**Replies:** 3\
**Last updated:** [December 27, 2019, 4:32pm UTC](https://discourse.julialang.org/t/sampling-from-posterior-predictive-distribution/32738 "2019-12-27T16:32:38Z")

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I’m completely new to Bayesian Inference stuff, now I’m reading “Statistical Rethinking” book chap. 3. There is a concept of “posterior predictive distribution” when I take the “sum” of weighted distributions according t…

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## [Fetch images from a NOIR camera on a Raspberry Pi](https://discourse.julialang.org/t/fetch-images-from-a-noir-camera-on-a-raspberry-pi/31054)

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**Author:** [@yakir12](https://discourse.julialang.org/u/yakir12)\
**Replies:** 3\
**Last updated:** [December 27, 2019, 2:17pm UTC](https://discourse.julialang.org/t/fetch-images-from-a-noir-camera-on-a-raspberry-pi/31054 "2019-12-27T14:17:09Z")

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The title… Does anyone know how I can grab images from a NOIR camera on an RPI?

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## [Histogram bars become line when many observations?](https://discourse.julialang.org/t/histogram-bars-become-line-when-many-observations/32639)

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**Author:** [@pearlzli](https://discourse.julialang.org/u/pearlzli)\
**Replies:** 6\
**Last updated:** [December 27, 2019, 1:26pm UTC](https://discourse.julialang.org/t/histogram-bars-become-line-when-many-observations/32639 "2019-12-27T13:26:46Z")

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I noticed that when there are a lot of (e.g. 10 million) observations, histogram produces a line plot instead of a bar plot: using Distributions, StatsPlots x = rand(Normal(), 1\_000\_000) histogram(x, bins = -5:0.2:5, la…

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## [Solves the linear system using CuArrays.jl](https://discourse.julialang.org/t/solves-the-linear-system-using-cuarrays-jl/32692)

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**Author:** [@FujiwaraTakumiEH](https://discourse.julialang.org/u/FujiwaraTakumiEH)\
**Replies:** 3\
**Last updated:** [December 27, 2019, 1:18pm UTC](https://discourse.julialang.org/t/solves-the-linear-system-using-cuarrays-jl/32692 "2019-12-27T13:18:58Z")

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I am new to GPU parallel computing. With my knowledge of CUSOLVER and CUSPARSE, I am sure that I can complete my task through them: Solving large linear sparse equations in parallel. I have read the documentation of CUD…

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## [Advice for simple (mildly large) Turing model](https://discourse.julialang.org/t/advice-for-simple-mildly-large-turing-model/32719)

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**Author:** [@opera\_malenky](https://discourse.julialang.org/u/opera_malenky)\
**Replies:** 9\
**Last updated:** [December 26, 2019, 10:00pm UTC](https://discourse.julialang.org/t/advice-for-simple-mildly-large-turing-model/32719 "2019-12-26T22:00:13Z")

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I have a simple Turing model I’ve been trying to implement, but I’ve been running into problems actually running it. I say simple, but my actual problem is not “small”, parameter-wise. I have about 18 groups, with about …

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## [Simplify MINLP problem to speed up results](https://discourse.julialang.org/t/simplify-minlp-problem-to-speed-up-results/32522)

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**Author:** [@Hector\_Esteban](https://discourse.julialang.org/u/Hector_Esteban)\
**Replies:** 5\
**Last updated:** [December 26, 2019, 6:41pm UTC](https://discourse.julialang.org/t/simplify-minlp-problem-to-speed-up-results/32522 "2019-12-26T18:41:31Z")

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Hey people, I want to optimize the path of a vehicle consisting on an array/vector of states of the form \[x\_i,y\_i,theta\_i\] and my control inputs are \[kappa\_i,dS\_i\]. As I am dealing with a MINLP problem (MI because I per…

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## [Libopenspecfun.dll could not be found error](https://discourse.julialang.org/t/libopenspecfun-dll-could-not-be-found-error/32649)

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**Author:** [@Xentios](https://discourse.julialang.org/u/Xentios)\
**Replies:** 3\
**Last updated:** [December 26, 2019, 6:38pm UTC](https://discourse.julialang.org/t/libopenspecfun-dll-could-not-be-found-error/32649 "2019-12-26T18:38:03Z")

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ERROR: LoadError: InitError: could not load library “C:\\Users\\Xentios.julia\\artifacts\\e062344a002c2afdfcf57091b975e56fd80de418\\bin\\libopenspecfun.dll” The specified module could not be found. I am using Gurobi with JuM…

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## [VegaLite.jl; what needs doing?](https://discourse.julialang.org/t/vegalite-jl-what-needs-doing/31940)

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**Author:** [@Usor](https://discourse.julialang.org/u/Usor)\
**Replies:** 12\
**Last updated:** [December 26, 2019, 1:24pm UTC](https://discourse.julialang.org/t/vegalite-jl-what-needs-doing/31940 "2019-12-26T13:24:50Z")

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I do not consider myself great at VegaLite.jl and I don’t know all its elements. I am still getting used to it more and more and don’t always have much time. Still I am interested in possibly helping with this project. I…

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