# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=399

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**Page:** 400

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## [Multiplying columns in DataFrames](https://discourse.julialang.org/t/multiplying-columns-in-dataframes/52069)

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**Author:** [@Smith](https://discourse.julialang.org/u/Smith)\
**Replies:** 10\
**Last updated:** [December 29, 2020, 6:51pm UTC](https://discourse.julialang.org/t/multiplying-columns-in-dataframes/52069 "2020-12-29T18:51:30Z")

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How can I multiply values in one column by other columns containing numerical data? Suppose a dataframe df\_1 is given by df\_1 = DataFrame(NAME = \["Aa","Bb","AB","CD","EF","GH"\], SCORE=\[0,1,10,20,30,45\], VALUE =\[400,200…

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## [Varargs of vectors and scalars under modulo](https://discourse.julialang.org/t/varargs-of-vectors-and-scalars-under-modulo/52548)

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**Author:** [@jakewilliami](https://discourse.julialang.org/u/jakewilliami)\
**Replies:** 5\
**Last updated:** [December 29, 2020, 4:45pm UTC](https://discourse.julialang.org/t/varargs-of-vectors-and-scalars-under-modulo/52548 "2020-12-29T16:45:57Z")

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How would I go about expanding the following code for any number of vectors (possibly using Iterators or @nloops)? My code below shows it working for the first three vectors. function list\_span(u̲::Vector{T}, v̲::Vecto…

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## [Recursive merge for named tuples](https://discourse.julialang.org/t/recursive-merge-for-named-tuples/52072)

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**Author:** [@cscherrer](https://discourse.julialang.org/u/cscherrer)\
**Replies:** 12\
**Last updated:** [December 29, 2020, 4:33pm UTC](https://discourse.julialang.org/t/recursive-merge-for-named-tuples/52072 "2020-12-29T16:33:50Z")

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On the Turing call this morning, I mentioned a need for a very efficient recursive merge on named tuples. @mohamed82008 asked where this need comes in, and… I guess it was too early? Coffee hadn’t kicked in? Something l…

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## [How to solve Lambert W function?](https://discourse.julialang.org/t/how-to-solve-lambert-w-function/52538)

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**Author:** [@Luigi\_Marongiu](https://discourse.julialang.org/u/Luigi_Marongiu)\
**Replies:** 17\
**Last updated:** [December 29, 2020, 3:48pm UTC](https://discourse.julialang.org/t/how-to-solve-lambert-w-function/52538 "2020-12-29T15:48:07Z")

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I have this equation Nₜ₊₁ = Nₜ exp\[μ(1-Nₜ/K)\] I would like to solve it the other way round: knowing Nₜ₊₁, I would like to estimate Nₜ. This is in the form y = x exp(a(1−x/k)) From this post looks like the solution is…

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## [Is it possible to use Julia as a co-simulator in conjunction to PSCAD/EMTDC or MATLAB](https://discourse.julialang.org/t/is-it-possible-to-use-julia-as-a-co-simulator-in-conjunction-to-pscad-emtdc-or-matlab/52516)

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**Author:** [@anchasatish](https://discourse.julialang.org/u/anchasatish)\
**Replies:** 2\
**Last updated:** [December 29, 2020, 2:10pm UTC](https://discourse.julialang.org/t/is-it-possible-to-use-julia-as-a-co-simulator-in-conjunction-to-pscad-emtdc-or-matlab/52516 "2020-12-29T14:10:41Z")

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I want to use Julia programming for running optimization of the system whose dynamic modeling is made in EMTDC/PSCAD, or MATLAB, i.e., optimization problem solved in Julia and output of this optimization solution is give…

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## [Basic remote procedure call via ssh from Linux to Windows](https://discourse.julialang.org/t/basic-remote-procedure-call-via-ssh-from-linux-to-windows/18743)

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**Author:** [@mgkuhn](https://discourse.julialang.org/u/mgkuhn)\
**Replies:** 8\
**Last updated:** [December 29, 2020, 12:52pm UTC](https://discourse.julialang.org/t/basic-remote-procedure-call-via-ssh-from-linux-to-windows/18743 "2020-12-29T12:52:48Z")

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I have a Julia application running under Linux. I would like to make a couple of remote function calls to another Julia process running on a specific Windows machine, because that Windows machine has special data-acquisi…

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## [3D bin packaging using Convex.jl](https://discourse.julialang.org/t/3d-bin-packaging-using-convex-jl/52571)

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**Author:** [@adropintheriver](https://discourse.julialang.org/u/adropintheriver)\
**Replies:** 0\
**Last updated:** [December 29, 2020, 12:36pm UTC](https://discourse.julialang.org/t/3d-bin-packaging-using-convex-jl/52571 "2020-12-29T12:36:08Z")

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Intent :Write a convex function that takes a set of points of shape (m,n) basically convexhull points by reading a CAD model. The function must return a Variable(from Convex.jl) of shape/size of the original vector (to…

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## [Best route for academic purchases of current-gen GPU components (non data-center parts)](https://discourse.julialang.org/t/best-route-for-academic-purchases-of-current-gen-gpu-components-non-data-center-parts/52539)

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**Author:** [@mkarikom](https://discourse.julialang.org/u/mkarikom)\
**Replies:** 1\
**Last updated:** [December 29, 2020, 11:31am UTC](https://discourse.julialang.org/t/best-route-for-academic-purchases-of-current-gen-gpu-components-non-data-center-parts/52539 "2020-12-29T11:31:18Z")

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Our procurement people use KFS to order this kind of stuff via purchase-orders on cdw, newegg, etc. Needless to say current-gen components (stuff like RTX 3xxx cards) are extremely hard to find at these outlets because …

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## [Can I extend other functions to make it compatible with Convex.jl (element-wise operation)](https://discourse.julialang.org/t/can-i-extend-other-functions-to-make-it-compatible-with-convex-jl-element-wise-operation/52565)

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**Author:** [@iHany](https://discourse.julialang.org/u/iHany)\
**Replies:** 0\
**Last updated:** [December 29, 2020, 10:15am UTC](https://discourse.julialang.org/t/can-i-extend-other-functions-to-make-it-compatible-with-convex-jl-element-wise-operation/52565 "2020-12-29T10:15:22Z")

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I’m using Convex.jl for convex optimisation. When constructing a function that I need to optimise, I used to extend methods of Convex to make it compatible with other functions, for example, # extend Convex method func…

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## [Julia crashes inside @threads with MPI](https://discourse.julialang.org/t/julia-crashes-inside-threads-with-mpi/52400)

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**Author:** [@Jae-Mo\_Lihm](https://discourse.julialang.org/u/Jae-Mo_Lihm)\
**Replies:** 5\
**Last updated:** [December 29, 2020, 7:41am UTC](https://discourse.julialang.org/t/julia-crashes-inside-threads-with-mpi/52400 "2020-12-29T07:41:52Z")

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Hi, I am trying to implement a program with hybrid MPI + Threads parallelization. In the following example, if I comment out all MPI-related lines, the code runs without any problem. However, if I run the code with the …

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## [LAPACK error from quadgk integration](https://discourse.julialang.org/t/lapack-error-from-quadgk-integration/52533)

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**Author:** [@Nkrause](https://discourse.julialang.org/u/Nkrause)\
**Replies:** 5\
**Last updated:** [December 29, 2020, 2:02am UTC](https://discourse.julialang.org/t/lapack-error-from-quadgk-integration/52533 "2020-12-29T02:02:03Z")

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I’m trying to integrate the following formula. It computes an electric potential at a point from a circular ring of charge. \\phi=\\int\_0^{2\\pi} \\frac{1}{\\sqrt{(x-cos(t))^2+(y-sin(t))^2+z^2)}}dt I’ve implemented the func…

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## [ERROR: LoadError: CUDNNError: CUDNN\_STATUS\_EXECUTION\_FAILED (code 8)](https://discourse.julialang.org/t/error-loaderror-cudnnerror-cudnn-status-execution-failed-code-8/52528)

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**Author:** [@vkv](https://discourse.julialang.org/u/vkv)\
**Replies:** 0\
**Last updated:** [December 28, 2020, 6:35pm UTC](https://discourse.julialang.org/t/error-loaderror-cudnnerror-cudnn-status-execution-failed-code-8/52528 "2020-12-28T18:35:23Z")

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I’m not able to get this code running on a GPU, but it works on CPU. I’ve tried different versions of CUDA, Nvidia drivers and Julia versions. Every time it ended up with the same error. As the code runs, the memory cons…

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## [Can indexes to DataFrame column be added to inprove selection performances?](https://discourse.julialang.org/t/can-indexes-to-dataframe-column-be-added-to-inprove-selection-performances/52456)

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**Author:** [@sylvaticus](https://discourse.julialang.org/u/sylvaticus)\
**Replies:** 2\
**Last updated:** [December 28, 2020, 1:11pm UTC](https://discourse.julialang.org/t/can-indexes-to-dataframe-column-be-added-to-inprove-selection-performances/52456 "2020-12-28T13:11:30Z")

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In relational databases like mysql we have the option to add “indexes” to columns in order to increase selection performances (at cost of worsening them when editing the data). Is there an option to add indexes to Julia…

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## [Any concise way to express simulation equations in Julia (like algebraic modelling language but not necessarily linked to optimisation problems)?](https://discourse.julialang.org/t/any-concise-way-to-express-simulation-equations-in-julia-like-algebraic-modelling-language-but-not-necessarily-linked-to-optimisation-problems/52449)

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**Author:** [@sylvaticus](https://discourse.julialang.org/u/sylvaticus)\
**Replies:** 4\
**Last updated:** [December 28, 2020, 10:41am UTC](https://discourse.julialang.org/t/any-concise-way-to-express-simulation-equations-in-julia-like-algebraic-modelling-language-but-not-necessarily-linked-to-optimisation-problems/52449 "2020-12-28T10:41:10Z")

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I know several Algebraic Modelling Languages in the context of optimisation, e.g. GAMS, Pyomo (Python) or JuMP (Julia). These allow you to express your objective function and your constraints with a syntax very concise a…

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## [Quadgk integration](https://discourse.julialang.org/t/quadgk-integration/52489)

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**Author:** [@Nkrause](https://discourse.julialang.org/u/Nkrause)\
**Replies:** 2\
**Last updated:** [December 28, 2020, 2:56am UTC](https://discourse.julialang.org/t/quadgk-integration/52489 "2020-12-28T02:56:21Z")

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Hello, I’ve got a function I’m trying to integrate, it’s a single variable for a position in space (an electric potential at that point). I’d like to pass my function a position, and have it evaluate the integral at that…

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## [Custom function for eigenvectors designed for my sparse matrix can't beat eigen](https://discourse.julialang.org/t/custom-function-for-eigenvectors-designed-for-my-sparse-matrix-cant-beat-eigen/52008)

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**Author:** [@physicophilic](https://discourse.julialang.org/u/physicophilic)\
**Replies:** 17\
**Last updated:** [December 27, 2020, 7:54pm UTC](https://discourse.julialang.org/t/custom-function-for-eigenvectors-designed-for-my-sparse-matrix-cant-beat-eigen/52008 "2020-12-27T19:54:04Z")

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I have a matrix of the form Jy = \[\[ 0 -im\*N1 0 0 ....... \] \[im\*N1 0 -im\*N2 0 ..... \] \[0 im\*N2 0 -im\*N3 ....\] ..................................…

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## [How in GRUtils or GLMakie to have the same range of colormap across plots?](https://discourse.julialang.org/t/how-in-grutils-or-glmakie-to-have-the-same-range-of-colormap-across-plots/52422)

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**Author:** [@vshesh](https://discourse.julialang.org/u/vshesh)\
**Replies:** 1\
**Last updated:** [December 26, 2020, 9:24pm UTC](https://discourse.julialang.org/t/how-in-grutils-or-glmakie-to-have-the-same-range-of-colormap-across-plots/52422 "2020-12-26T21:24:43Z")

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I’m trying to compare distance functions looking at a heatmap of the distance matrix and can’t see anywhere in the documentation how to tell the plot function what the “range” of the data to apply to the colormap is. i …

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## [Ridge Regression using Turing.jl](https://discourse.julialang.org/t/ridge-regression-using-turing-jl/52378)

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**Author:** [@Michaela\_Maskova](https://discourse.julialang.org/u/Michaela_Maskova)\
**Replies:** 4\
**Last updated:** [December 26, 2020, 7:56pm UTC](https://discourse.julialang.org/t/ridge-regression-using-turing-jl/52378 "2020-12-26T19:56:27Z")

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Hi everyone, I’m trying to create a model in Turing.jl for Ridge Regression to use HMC. However, I need to sample two parameters, alpha and theta which are dependant on each other via θ ~ MvNormal(zeros(3),α^(-1)) α ~ …

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## [Is it possible to use @static to distinguish CPU or GPU call in CUDA?](https://discourse.julialang.org/t/is-it-possible-to-use-static-to-distinguish-cpu-or-gpu-call-in-cuda/52366)

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**Author:** [@HaoxuanGuo](https://discourse.julialang.org/u/HaoxuanGuo)\
**Replies:** 2\
**Last updated:** [December 26, 2020, 7:37am UTC](https://discourse.julialang.org/t/is-it-possible-to-use-static-to-distinguish-cpu-or-gpu-call-in-cuda/52366 "2020-12-26T07:37:38Z")

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As we all know, some codes can not run on GPU. But there will be some alternative way to solve it. For example, sqrt can not run on GPU due to a \_fpow error. But CUDA.sqrt is an alternative solution. In this condition, …

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## [Makie memory leak?](https://discourse.julialang.org/t/makie-memory-leak/52362)

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**Author:** [@LaurentPlagne](https://discourse.julialang.org/u/LaurentPlagne)\
**Replies:** 10\
**Last updated:** [December 25, 2020, 5:25pm UTC](https://discourse.julialang.org/t/makie-memory-leak/52362 "2020-12-25T17:25:31Z")

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Hi, I do not understand why the following MWE consumes more an more memory until crash: using GLMakie,AbstractPlotting,ImageCore function leak(img,i) fn=string(i)\*".png" scene = AbstractPlotting.image(rotr90(i…

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## [Google's MuZero](https://discourse.julialang.org/t/googles-muzero/52364)

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**Author:** [@StatisticalMouse](https://discourse.julialang.org/u/StatisticalMouse)\
**Replies:** 0\
**Last updated:** [December 25, 2020, 10:42am UTC](https://discourse.julialang.org/t/googles-muzero/52364 "2020-12-25T10:42:56Z")

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This looks like a big deal. It uses model-based reinforcement learning and can learn to play both chess and Pac-Man. Abstract from the Science article: " Constructing agents with planning capabilities has long been one …

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## [Maximum Likelihood: Normal Linear Model](https://discourse.julialang.org/t/maximum-likelihood-normal-linear-model/11664)

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**Author:** [@Donald\_Lacombe](https://discourse.julialang.org/u/Donald_Lacombe)\
**Replies:** 31\
**Last updated:** [December 25, 2020, 2:14am UTC](https://discourse.julialang.org/t/maximum-likelihood-normal-linear-model/11664 "2020-12-25T02:14:34Z")

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Hello, I’m trying to optimize a simple normal linear model likelihood function and have two questions. The code I am using is below: using Optim nobs = 500 nvar = 1 β = ones(nvar)\*3.0 x = \[ones(nobs) randn(nobs,nvar-1…

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## [Float64 Julian Date from AstroTime](https://discourse.julialang.org/t/float64-julian-date-from-astrotime/52341)

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**Author:** [@rbl100](https://discourse.julialang.org/u/rbl100)\
**Replies:** 1\
**Last updated:** [December 24, 2020, 8:26pm UTC](https://discourse.julialang.org/t/float64-julian-date-from-astrotime/52341 "2020-12-24T20:26:51Z")

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I can use AstroTime julian(UTCEpoch(2020,12,24,12,0,0.0)) to give me 2.459208e6 days. How do I turn that into a simple float? Float64() gives an error. I’m sure I’m missing something simple. Thanks in advance.

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## [Getting INVALID\_MODEL error while solving RMSE](https://discourse.julialang.org/t/getting-invalid-model-error-while-solving-rmse/52153)

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**Author:** [@gaadis](https://discourse.julialang.org/u/gaadis)\
**Replies:** 8\
**Last updated:** [December 24, 2020, 2:12pm UTC](https://discourse.julialang.org/t/getting-invalid-model-error-while-solving-rmse/52153 "2020-12-24T14:12:28Z")

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I’m attempting to minimize an RMSE where the optimized coefficients alpha and beta give a forecasted value (xnext) from the original value (x\_k). Initially it did not let me add the square root in the objective function…

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## [DDE too stiff? Required tolerances are too slow](https://discourse.julialang.org/t/dde-too-stiff-required-tolerances-are-too-slow/52259)

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**Author:** [@ANasc](https://discourse.julialang.org/u/ANasc)\
**Replies:** 4\
**Last updated:** [December 24, 2020, 4:51am UTC](https://discourse.julialang.org/t/dde-too-stiff-required-tolerances-are-too-slow/52259 "2020-12-24T04:51:49Z")

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Hi, I have a system of DDEs that model host-parasite dynamics in a seasonal environment and I am having some issues because (I think) the equations are so stiff. Basically, when the number of hosts S is too high (\> abou…

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## [Reduce memory allocation for repeatedly solving problem using Optim.jl](https://discourse.julialang.org/t/reduce-memory-allocation-for-repeatedly-solving-problem-using-optim-jl/52292)

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**Author:** [@MFairley](https://discourse.julialang.org/u/MFairley)\
**Replies:** 0\
**Last updated:** [December 23, 2020, 8:16pm UTC](https://discourse.julialang.org/t/reduce-memory-allocation-for-repeatedly-solving-problem-using-optim-jl/52292 "2020-12-23T20:16:29Z")

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I’m trying to re-solve a problem with different parameter values many times using Optim.jl. My current code allocates a lot of memory because a new TwiceDifferentiable and TwiceDifferentiableConstraints is created for ev…

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## [CUDA.jl vs. ArrayFire.jl on Windows 10 VM running on VMWare VSphere](https://discourse.julialang.org/t/cuda-jl-vs-arrayfire-jl-on-windows-10-vm-running-on-vmware-vsphere/52078)

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**Author:** [@Zhong\_Pan](https://discourse.julialang.org/u/Zhong_Pan)\
**Replies:** 1\
**Last updated:** [December 23, 2020, 4:27pm UTC](https://discourse.julialang.org/t/cuda-jl-vs-arrayfire-jl-on-windows-10-vm-running-on-vmware-vsphere/52078 "2020-12-23T16:27:29Z")

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We need to speed up some double-precision calculations that are mainly just complex array calculations and FFT/IFFT. We were using NVIDIA Geforce RTX 2080 Ti on a PC and the speedup vs CPU is very good but not sufficient…

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## [GeoStats.jl Survey 2020](https://discourse.julialang.org/t/geostats-jl-survey-2020/52267)

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**Author:** [@juliohm](https://discourse.julialang.org/u/juliohm)\
**Replies:** 0\
**Last updated:** [December 23, 2020, 10:57am UTC](https://discourse.julialang.org/t/geostats-jl-survey-2020/52267 "2020-12-23T10:57:43Z")

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Are you using GeoStats.jl in your work? Please consider this quick survey: https://forms.gle/a5tHHQwc9RudkMzcA We will use the results to better plan our efforts next year. Thank you and happy new year!

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## [Using Transformers.jl for time series classification?](https://discourse.julialang.org/t/using-transformers-jl-for-time-series-classification/50509)

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**Author:** [@lorrp1](https://discourse.julialang.org/u/lorrp1)\
**Replies:** 10\
**Last updated:** [December 23, 2020, 5:07am UTC](https://discourse.julialang.org/t/using-transformers-jl-for-time-series-classification/50509 "2020-12-23T05:07:00Z")

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Hello, has anyone tried using Transformers.jl for time series classification? is it possible? @chengchingwen

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## [Implementing sparse Gaussian process model with Turing and Stheno](https://discourse.julialang.org/t/implementing-sparse-gaussian-process-model-with-turing-and-stheno/46886)

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**Author:** [@ElOceanografo](https://discourse.julialang.org/u/ElOceanografo)\
**Replies:** 15\
**Last updated:** [December 23, 2020, 12:09am UTC](https://discourse.julialang.org/t/implementing-sparse-gaussian-process-model-with-turing-and-stheno/46886 "2020-12-23T00:09:19Z")

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I’ve built a Turing model for some non-Gaussian data which contains a latent Gaussian process for spatial autocorrelation. I’ve run it on a small simulated dataset to confirm that it works. Now I want to run it on my r…

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