# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?page=397

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**Page:** 398

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## [How to close a remote Timer?](https://discourse.julialang.org/t/how-to-close-a-remote-timer/53295)

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**Author:** [@Christian\_Dengler](https://discourse.julialang.org/u/Christian_Dengler)\
**Replies:** 3\
**Last updated:** [January 14, 2021, 7:47am UTC](https://discourse.julialang.org/t/how-to-close-a-remote-timer/53295 "2021-01-14T07:47:27Z")

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I want to run mutliple procedures in parallel on a server in fixed time ntervals. The idea was to ,e.g., simply use “@spawnat :any” together with “Timer”, however, I cannot find a way to stop the Timer once its started. …

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## [Need advice when data almost (but not quite) fit log normal dist](https://discourse.julialang.org/t/need-advice-when-data-almost-but-not-quite-fit-log-normal-dist/53287)

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**Author:** [@mthelm85](https://discourse.julialang.org/u/mthelm85)\
**Replies:** 7\
**Last updated:** [January 13, 2021, 6:38pm UTC](https://discourse.julialang.org/t/need-advice-when-data-almost-but-not-quite-fit-log-normal-dist/53287 "2021-01-13T18:38:37Z")

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This isn’t really a question about Julia so maybe this should be tagged as Offtopic, but I’m working with a data set that has several series of data that all closely follow a log normal distribution, but not quite. The p…

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## [Optim.jl wrongly reporting success](https://discourse.julialang.org/t/optim-jl-wrongly-reporting-success/53174)

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**Author:** [@Albert\_Zevelev](https://discourse.julialang.org/u/Albert_Zevelev)\
**Replies:** 4\
**Last updated:** [January 13, 2021, 6:44pm UTC](https://discourse.julialang.org/t/optim-jl-wrongly-reporting-success/53174 "2021-01-13T18:44:17Z")

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I’m solving for the MLE. using Distributions, Random, Optim; DGP\_True = LogNormal(17,7); Random.seed!(123); const d\_train = rand(DGP\_True, 1\_000) const d\_test = rand(DGP\_True, 1\_000) # LogNormal function loglike(θ) …

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## [Tensor contractions with symmetries](https://discourse.julialang.org/t/tensor-contractions-with-symmetries/52980)

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**Author:** [@Nellatur](https://discourse.julialang.org/u/Nellatur)\
**Replies:** 3\
**Last updated:** [January 13, 2021, 4:48pm UTC](https://discourse.julialang.org/t/tensor-contractions-with-symmetries/52980 "2021-01-13T16:48:12Z")

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I have some tensor contractions, e.g., A\[abcd\] B\[cdef\] = C\[abef\], where A\[abcd\] = A\[badc\] and B\[cdef\] = B\[dcfe\]. I did not find information about symmetry in einsum in NumPy. Is there any Julia package can handle tensor …

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## [Gradient error in Flux model inputs](https://discourse.julialang.org/t/gradient-error-in-flux-model-inputs/53259)

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**Author:** [@Elmo](https://discourse.julialang.org/u/Elmo)\
**Replies:** 5\
**Last updated:** [January 13, 2021, 4:13pm UTC](https://discourse.julialang.org/t/gradient-error-in-flux-model-inputs/53259 "2021-01-13T16:13:54Z")

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Hi all, I am trying to construct a loss function in Flux that is composed of a typical mean squared error component, as well as a derivative component. For some reason I get a Can't differentiate foreigncall expression e…

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## [How to find the index of a Dense Axis Array?](https://discourse.julialang.org/t/how-to-find-the-index-of-a-dense-axis-array/53204)

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**Author:** [@fredih](https://discourse.julialang.org/u/fredih)\
**Replies:** 3\
**Last updated:** [January 13, 2021, 12:35pm UTC](https://discourse.julialang.org/t/how-to-find-the-index-of-a-dense-axis-array/53204 "2021-01-13T12:35:46Z")

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Hello! I know I can use something like findall(x-\>x==1, myArray) to find the indices of elements of value 1 inside myArray. However, my variables in my optimization problem are DenseAxisArrays, as they are indexed with…

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## [Move a plane with slider in Makie.jl](https://discourse.julialang.org/t/move-a-plane-with-slider-in-makie-jl/53258)

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**Author:** [@Flausi](https://discourse.julialang.org/u/Flausi)\
**Replies:** 0\
**Last updated:** [January 12, 2021, 10:06pm UTC](https://discourse.julialang.org/t/move-a-plane-with-slider-in-makie-jl/53258 "2021-01-12T22:06:53Z")

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Hello, I tried to use Makie.jl to move a layer in a spatial plot via a slider and update the data depending on how the slider is set. This actually works quite well, but the layer is not moved with the ‘transformation -…

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## [Take gradient of parameters not working](https://discourse.julialang.org/t/take-gradient-of-parameters-not-working/53250)

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**Author:** [@Elmo](https://discourse.julialang.org/u/Elmo)\
**Replies:** 0\
**Last updated:** [January 12, 2021, 8:20pm UTC](https://discourse.julialang.org/t/take-gradient-of-parameters-not-working/53250 "2021-01-12T20:20:58Z")

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Hi all! I am trying to construct a loss function in Flux (v0.11.2) that regularizes the parameters relative to some number (not 0). Below is a minimal working example, does anybody know why the gradients are nothing? us…

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## [SingularSpectrumAnalysis and CPU load](https://discourse.julialang.org/t/singularspectrumanalysis-and-cpu-load/53212)

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**Author:** [@Colin\_Beckingham](https://discourse.julialang.org/u/Colin_Beckingham)\
**Replies:** 3\
**Last updated:** [January 12, 2021, 6:09pm UTC](https://discourse.julialang.org/t/singularspectrumanalysis-and-cpu-load/53212 "2021-01-12T18:09:21Z")

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SSA does a good job of extracting trend and seasonality from a time series. However widening the window on a large dataset puts quite a load on my CPU (GPU is too old to contribute to calculation in Julia) heats up my CP…

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## [CUDA.jl Differentiation Error](https://discourse.julialang.org/t/cuda-jl-differentiation-error/53011)

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**Author:** [@Honza9723](https://discourse.julialang.org/u/Honza9723)\
**Replies:** 5\
**Last updated:** [January 12, 2021, 1:28pm UTC](https://discourse.julialang.org/t/cuda-jl-differentiation-error/53011 "2021-01-12T13:28:17Z")

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Dear All, while working on my project (epidemic model, solved using PINN), I tried to port my code to GPU. While function (loss function of my neural network) works and delivers reasonable speed up, while computing grad…

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## [Second derivative of shape functions in JuAFEM](https://discourse.julialang.org/t/second-derivative-of-shape-functions-in-juafem/53160)

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**Author:** [@FrootLoops](https://discourse.julialang.org/u/FrootLoops)\
**Replies:** 3\
**Last updated:** [January 12, 2021, 8:56am UTC](https://discourse.julialang.org/t/second-derivative-of-shape-functions-in-juafem/53160 "2021-01-12T08:56:23Z")

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Hi, is there already a implemented function, which computes the second derivatives of the shape function at a given point? I am working with PDEs of higher-order and therefore need high order derivates of the used ansa…

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## [DiffEq tolerances on ContinuousCallbacks?](https://discourse.julialang.org/t/diffeq-tolerances-on-continuouscallbacks/53181)

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**Author:** [@klaff](https://discourse.julialang.org/u/klaff)\
**Replies:** 7\
**Last updated:** [January 12, 2021, 6:49am UTC](https://discourse.julialang.org/t/diffeq-tolerances-on-continuouscallbacks/53181 "2021-01-12T06:49:12Z")

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I’m troubleshooting some friction models and trying to understand what I’m seeing. I’ve made a MWE by taking the bouncing ball model from the DiffEq docs and changing the coefficient of restitution to 0.1 instead of 1.0 …

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## [How can I set and get the session of the request from browser in Genie.jl?](https://discourse.julialang.org/t/how-can-i-set-and-get-the-session-of-the-request-from-browser-in-genie-jl/52883)

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**Author:** [@AquaIndigo](https://discourse.julialang.org/u/AquaIndigo)\
**Replies:** 6\
**Last updated:** [January 12, 2021, 4:36am UTC](https://discourse.julialang.org/t/how-can-i-set-and-get-the-session-of-the-request-from-browser-in-genie-jl/52883 "2021-01-12T04:36:58Z")

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Hello, I’m doing my Database course project using Genie as the back-end server, and I’m wondering how to set and save the session. And my efforts are as follows: route("/api/login") do uid = haskey(@params, :id) ? @p…

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## [PyCall.jl with PermutedDimsArray, StridedSubArray, and ReinterperetArray](https://discourse.julialang.org/t/pycall-jl-with-permuteddimsarray-stridedsubarray-and-reinterperetarray/53146)

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**Author:** [@mkitti](https://discourse.julialang.org/u/mkitti)\
**Replies:** 2\
**Last updated:** [January 12, 2021, 12:06am UTC](https://discourse.julialang.org/t/pycall-jl-with-permuteddimsarray-stridedsubarray-and-reinterperetarray/53146 "2021-01-12T00:06:00Z")

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I have been working on Napari.jl which is a Julia package for Napari, a multidimensional image viewer written in Python developed at Chan-Zuckerberg Initiative’s Biohub with many contributors from the field of biological…

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## [Is it a good time for a PyTorch developer to move to Julia? If so, Flux? Knet?](https://discourse.julialang.org/t/is-it-a-good-time-for-a-pytorch-developer-to-move-to-julia-if-so-flux-knet/38453)

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**Author:** [@Alon](https://discourse.julialang.org/u/Alon)\
**Replies:** 52\
**Last updated:** [January 11, 2021, 9:51pm UTC](https://discourse.julialang.org/t/is-it-a-good-time-for-a-pytorch-developer-to-move-to-julia-if-so-flux-knet/38453 "2021-01-11T21:51:35Z")

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For me, the move from Keras to PyTorch was the best decision in my AI career. I am considering moving from Python to Julia because of performance and because the “NumPy” is built-in (as it was in Matlab rest its soul). …

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## [Poor linear relaxation](https://discourse.julialang.org/t/poor-linear-relaxation/53170)

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**Author:** [@angeloaliano1](https://discourse.julialang.org/u/angeloaliano1)\
**Replies:** 1\
**Last updated:** [January 11, 2021, 8:12pm UTC](https://discourse.julialang.org/t/poor-linear-relaxation/53170 "2021-01-11T20:12:20Z")

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Dear users, I have a MIP problem whose linear relaxation is very poor. Observe the report of CPLEX below: (Gap greater to 999.99%, then the symbol “–”). Does have any parameter in CPLEX to set to improve these perf…

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## [Having a hard time visualizing LazySets.HPolyHedron & HPolytope](https://discourse.julialang.org/t/having-a-hard-time-visualizing-lazysets-hpolyhedron-hpolytope/52721)

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**Author:** [@adropintheriver](https://discourse.julialang.org/u/adropintheriver)\
**Replies:** 1\
**Last updated:** [January 11, 2021, 6:10pm UTC](https://discourse.julialang.org/t/having-a-hard-time-visualizing-lazysets-hpolyhedron-hpolytope/52721 "2021-01-11T18:10:28Z")

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Q.1 what is the right way to render the following a. HPolyhedron/HPolytope b. Set of points (3D) so the code below from Polyhedra docs A = rand(HPolyhedron,dim=3) HPoly = Polytope(constraints\_list(A)) remove\_redunda…

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## [Last mile of BlackBoxOptim](https://discourse.julialang.org/t/last-mile-of-blackboxoptim/53171)

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**Author:** [@zxjroger](https://discourse.julialang.org/u/zxjroger)\
**Replies:** 0\
**Last updated:** [January 11, 2021, 6:05pm UTC](https://discourse.julialang.org/t/last-mile-of-blackboxoptim/53171 "2021-01-11T18:05:17Z")

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I am doing Monte Carlo study of the simulated method of moments estimator for my economic model. Since the objective function is not differentiable, I am using adaptive\_de\_rand\_1\_bin\_radiuslimited in BlackBoxOptim.jl as …

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## [Why are vertices of every LazySets.VPolygon or VPolytope given as 1 D Array and not based on the shape of the object?](https://discourse.julialang.org/t/why-are-vertices-of-every-lazysets-vpolygon-or-vpolytope-given-as-1-d-array-and-not-based-on-the-shape-of-the-object/52719)

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**Author:** [@adropintheriver](https://discourse.julialang.org/u/adropintheriver)\
**Replies:** 1\
**Last updated:** [January 11, 2021, 5:49pm UTC](https://discourse.julialang.org/t/why-are-vertices-of-every-lazysets-vpolygon-or-vpolytope-given-as-1-d-array-and-not-based-on-the-shape-of-the-object/52719 "2021-01-11T17:49:32Z")

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A = rand(HPolyhedron,dim=3) Av = tovrep(A) Av.vertices gives an 11-element Array{Array{Float64,1},1} and not a 3 Dimensional array of 11 elements, also how can i convert these vertices to BasicGeometry.Point3d without u…

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## [Why I get 'RefValue{SubArray{Int64' and not "simply" 'SubArray{Int64'](https://discourse.julialang.org/t/why-i-get-refvalue-subarray-int64-and-not-simply-subarray-int64/52286)

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**Author:** [@rocco\_sprmnt21](https://discourse.julialang.org/u/rocco_sprmnt21)\
**Replies:** 13\
**Last updated:** [January 11, 2021, 4:42pm UTC](https://discourse.julialang.org/t/why-i-get-refvalue-subarray-int64-and-not-simply-subarray-int64/52286 "2021-01-11T16:42:01Z")

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I have this in these cases of single columns df = DataFrame(x = \[1, 1, 2, 2\], y = \[1, 2, 101, 102\]); gd = groupby(df, :x); julia\> combine(gd,:x=\>(X-\>Ref(X))=\>:rx) 2×2 DataFrame Row │ x rx │ Int64 Su…

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## [Can't compile a GPU kernel function for =\>](https://discourse.julialang.org/t/cant-compile-a-gpu-kernel-function-for/53100)

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**Author:** [@Stephan\_Meyn](https://discourse.julialang.org/u/Stephan_Meyn)\
**Replies:** 2\
**Last updated:** [January 11, 2021, 10:36am UTC](https://discourse.julialang.org/t/cant-compile-a-gpu-kernel-function-for/53100 "2021-01-11T10:36:55Z")

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I’m trying to persuade CUDA.jl to compile a kernel function. After reducing the issue I have come to this sample code using CUDA x=Float32(2.0) knots =CuArray{Float32,1}(\[1.2, 2.0, 3.0\]) mapOp(v::Float32)::Int = v \>= x…

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## [What shape should data be in to perform a linear fit with GLM?](https://discourse.julialang.org/t/what-shape-should-data-be-in-to-perform-a-linear-fit-with-glm/53120)

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**Author:** [@alice](https://discourse.julialang.org/u/alice)\
**Replies:** 7\
**Last updated:** [January 11, 2021, 9:22am UTC](https://discourse.julialang.org/t/what-shape-should-data-be-in-to-perform-a-linear-fit-with-glm/53120 "2021-01-11T09:22:15Z")

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I am trying to fit some data with a variable number of dimensions using a linear fit. I am currently trying to use GLM, but I am happy to use any other library. I’ve been running in to a lot of trouble getting the data …

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## [Using Julia to solve semidefinite programming problem that has vector solutions](https://discourse.julialang.org/t/using-julia-to-solve-semidefinite-programming-problem-that-has-vector-solutions/53134)

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**Author:** [@cheng\_chen](https://discourse.julialang.org/u/cheng_chen)\
**Replies:** 6\
**Last updated:** [January 11, 2021, 6:50am UTC](https://discourse.julialang.org/t/using-julia-to-solve-semidefinite-programming-problem-that-has-vector-solutions/53134 "2021-01-11T06:50:02Z")

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Hi everyone! I need to use Julia to solve a SDP. What would you suggest to use to solve the SDP? I tried Convex and JuMP with ProxSDP, I couldn’t get it to work.

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## [Errors during test CUDA](https://discourse.julialang.org/t/errors-during-test-cuda/53142)

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**Author:** [@youeh1](https://discourse.julialang.org/u/youeh1)\
**Replies:** 0\
**Last updated:** [January 11, 2021, 6:09am UTC](https://discourse.julialang.org/t/errors-during-test-cuda/53142 "2021-01-11T06:09:42Z")

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Hi, I just format my labtop and install graphics drivers CUDA 11.2 julia (1.53) I added CUDA.jl and downloaded cuDNN111 via artifact and had no errors by here. I ran Pkg\> test CUDA, now I got errors ┌ Error: Excep…

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## [Suppress license output from solver in JuMP.Model](https://discourse.julialang.org/t/suppress-license-output-from-solver-in-jump-model/20828)

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**Author:** [@torgo](https://discourse.julialang.org/u/torgo)\
**Replies:** 13\
**Last updated:** [January 11, 2021, 1:24am UTC](https://discourse.julialang.org/t/suppress-license-output-from-solver-in-jump-model/20828 "2021-01-11T01:24:41Z")

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using JuMP, Gurobi m = Model(solver=GurobiSolver(OutputFlag=0)) I have a program where the second line gets called frequently. Every time it does, this gets printed to stdout: Academic license - for non-commercial use…

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## [ForwardDiff.jl \\ Optim.jl and recompilation for any vector size](https://discourse.julialang.org/t/forwarddiff-jl-optim-jl-and-recompilation-for-any-vector-size/53104)

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**Author:** [@PharmCat](https://discourse.julialang.org/u/PharmCat)\
**Replies:** 4\
**Last updated:** [January 10, 2021, 5:54pm UTC](https://discourse.julialang.org/t/forwarddiff-jl-optim-jl-and-recompilation-for-any-vector-size/53104 "2021-01-10T17:54:21Z")

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I try to optimize function with different variable vector size. And I think that for each task type method is compilated again. Main function is type-stable as I think by @code\_warntype and @code\_typed. And probably eac…

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## [MLJ - Error - Models support multitarget but measures do not?](https://discourse.julialang.org/t/mlj-error-models-support-multitarget-but-measures-do-not/53091)

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**Author:** [@diadora77](https://discourse.julialang.org/u/diadora77)\
**Replies:** 2\
**Last updated:** [January 10, 2021, 1:50pm UTC](https://discourse.julialang.org/t/mlj-error-models-support-multitarget-but-measures-do-not/53091 "2021-01-10T13:50:22Z")

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Hi- I’m relatively new to MLJ but have decent knowledge and experience using ScikitLearn. MLJ looks promising with more flexibility in model creation. In testing it out for my research, I’m struggling to get a basic mod…

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## [Drawing text over pixels of an image](https://discourse.julialang.org/t/drawing-text-over-pixels-of-an-image/53040)

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**Author:** [@claforte](https://discourse.julialang.org/u/claforte)\
**Replies:** 2\
**Last updated:** [January 10, 2021, 5:37am UTC](https://discourse.julialang.org/t/drawing-text-over-pixels-of-an-image/53040 "2021-01-10T05:37:23Z")

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Hello Julia plotting experts, I want to annotate images by drawing text over the pixels of an image. This is to generate a lossless video where each frame shows an animated grid of tiles, each output by a different super…

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## [Nonlinear fit with Flux](https://discourse.julialang.org/t/nonlinear-fit-with-flux/53075)

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**Author:** [@edwinb-ai](https://discourse.julialang.org/u/edwinb-ai)\
**Replies:** 2\
**Last updated:** [January 10, 2021, 4:10am UTC](https://discourse.julialang.org/t/nonlinear-fit-with-flux/53075 "2021-01-10T04:10:43Z")

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using Flux using Flux.Losses: mse using Flux.Data: DataLoader using Plots using Random gr() nonlinear(x) = sin(x) + sin(2 \* x) + 0.1f0 \* randn() function get\_data() points = 1000 xvals = collect(Float32, range…

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## [Cuda cg + ilu?](https://discourse.julialang.org/t/cuda-cg-ilu/53069)

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**Author:** [@Omega-xyZac](https://discourse.julialang.org/u/Omega-xyZac)\
**Replies:** 4\
**Last updated:** [January 9, 2021, 12:38am UTC](https://discourse.julialang.org/t/cuda-cg-ilu/53069 "2021-01-09T00:38:24Z")

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Hi all, I’m looking to use a GPU CG method with an ILU preconditioner. I’m currently using a CPU CG method through IterativeSolvers and ILU through IncompleteLU.jl . The CG method from IterativeSolvers is easily extende…

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