# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=517

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**Page:** 518

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## [Identifying wokers and CPU sockets](https://discourse.julialang.org/t/identifying-wokers-and-cpu-sockets/17776)

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**Author:** [@Julien](https://discourse.julialang.org/u/Julien)\
**Replies:** 1\
**Last updated:** [November 20, 2018, 3:18pm UTC](https://discourse.julialang.org/t/identifying-wokers-and-cpu-sockets/17776 "2018-11-20T15:18:08Z")

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Hi, When working on a cluster, is there a way to know which worker belongs to which socket? I am trying to send tasks to a group of workers belonging to the same socket. Thanks a lot.

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## [Writing a simple production scheduling (optimal control) problem in JuMP](https://discourse.julialang.org/t/writing-a-simple-production-scheduling-optimal-control-problem-in-jump/17748)

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**Author:** [@rotsoc](https://discourse.julialang.org/u/rotsoc)\
**Replies:** 4\
**Last updated:** [November 20, 2018, 2:31pm UTC](https://discourse.julialang.org/t/writing-a-simple-production-scheduling-optimal-control-problem-in-jump/17748 "2018-11-20T14:31:18Z")

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Hi! I am working through the introductory exercises of “Linear Programming & Network Flows” by Bazaraa et.al by writing and solving them as JuMP programs. Actually, my question is about an example from the Introduction. …

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## [ReferenceFrameRotations v0.5.0 has been tagged](https://discourse.julialang.org/t/referenceframerotations-v0-5-0-has-been-tagged/17725)

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**Author:** [@Ronis\_BR](https://discourse.julialang.org/u/Ronis_BR)\
**Replies:** 0\
**Last updated:** [November 19, 2018, 6:34pm UTC](https://discourse.julialang.org/t/referenceframerotations-v0-5-0-has-been-tagged/17725 "2018-11-19T18:34:55Z")

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Hi guys! This is not directly related to Astro/Space, but I did not find a more appropriate local to post this. I have just tagged the v0.5.0 do ReferenceFrameRotations.jl. Now, we have full support for the four differ…

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## [Tables.jl: a table interface for everyone](https://discourse.julialang.org/t/tables-jl-a-table-interface-for-everyone/14071)

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**Author:** [@quinnj](https://discourse.julialang.org/u/quinnj)\
**Replies:** 19\
**Last updated:** [November 19, 2018, 5:00pm UTC](https://discourse.julialang.org/t/tables-jl-a-table-interface-for-everyone/14071 "2018-11-19T17:00:09Z")

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I’ve had several people direct message me over the last couple of days asking for details about a new package I’ve been working: Tables.jl, so I thought I’d write up a quick post on what it is, where it came from, and wh…

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## [Any Julia's equivalent to R's packages mcgv or mixed-effects models larger than memory?](https://discourse.julialang.org/t/any-julias-equivalent-to-rs-packages-mcgv-or-mixed-effects-models-larger-than-memory/11865)

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**Author:** [@Juan](https://discourse.julialang.org/u/Juan)\
**Replies:** 9\
**Last updated:** [November 19, 2018, 4:41pm UTC](https://discourse.julialang.org/t/any-julias-equivalent-to-rs-packages-mcgv-or-mixed-effects-models-larger-than-memory/11865 "2018-11-19T16:41:28Z")

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Hello. I’m interested in fitting mixed effects models with large dataset that don’t fit on memory. R’s lme4 it’s too slow and doesn’t work if the dataset is large (a fraction of your RAM). speedglm and mgcv are a litt…

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## [DataTables or DataFrames?](https://discourse.julialang.org/t/datatables-or-dataframes/3160)

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**Author:** [@natashawatkins](https://discourse.julialang.org/u/natashawatkins)\
**Replies:** 32\
**Last updated:** [November 19, 2018, 4:38pm UTC](https://discourse.julialang.org/t/datatables-or-dataframes/3160 "2018-11-19T16:38:26Z")

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After a lot of reading, I’m still not certain about the state of data handling in Julia. My understanding is there is a migration over to DataTables due to type-safety considerations, however there are still a number of…

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## [Disk based data manipulation framework needed](https://discourse.julialang.org/t/disk-based-data-manipulation-framework-needed/6303)

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**Author:** [@xiaodai](https://discourse.julialang.org/u/xiaodai)\
**Replies:** 21\
**Last updated:** [October 31, 2017, 8:20pm UTC](https://discourse.julialang.org/t/disk-based-data-manipulation-framework-needed/6303 "2017-10-31T20:20:04Z")

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SAS is big in the corporate world. I work in the finance industry and SAS is still quite big. To be honest, using SAS is a pain. SAS can’t even syntax highlight its own language properly. But it’s still there because it …

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## [Challenge: Hopf Fibration using Julia](https://discourse.julialang.org/t/challenge-hopf-fibration-using-julia/17697)

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**Author:** [@jandehaan](https://discourse.julialang.org/u/jandehaan)\
**Replies:** 2\
**Last updated:** [November 19, 2018, 11:30am UTC](https://discourse.julialang.org/t/challenge-hopf-fibration-using-julia/17697 "2018-11-19T11:30:07Z")

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If you are looking for a visualization challenge, try visualizing Hopf Fibrations. Niles Johnson was able to do it using the free mathematics software Sage including the Tachyon ray tracer. Visualization - Lecture -…

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## [Incorrect results for sinpi and cospi when using fastmath mode?](https://discourse.julialang.org/t/incorrect-results-for-sinpi-and-cospi-when-using-fastmath-mode/17662)

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**Author:** [@Seif\_Shebl](https://discourse.julialang.org/u/Seif_Shebl)\
**Replies:** 4\
**Last updated:** [November 18, 2018, 3:35pm UTC](https://discourse.julialang.org/t/incorrect-results-for-sinpi-and-cospi-when-using-fastmath-mode/17662 "2018-11-18T15:35:25Z")

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When firing up Julia with the --math-mode=fast option, I get incorrect results for sinpi and cospi functions. Is this a bug or am I missing something? With the default math mode: julia\> a = rand(5) 5-element Array{Floa…

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## [RigidBodyDynamics.jl attaching a new rigid body to the system](https://discourse.julialang.org/t/rigidbodydynamics-jl-attaching-a-new-rigid-body-to-the-system/17451)

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**Author:** [@phelipe](https://discourse.julialang.org/u/phelipe)\
**Replies:** 4\
**Last updated:** [November 18, 2018, 3:11pm UTC](https://discourse.julialang.org/t/rigidbodydynamics-jl-attaching-a-new-rigid-body-to-the-system/17451 "2018-11-18T15:11:35Z")

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Is it possible to add an extra load to a mechanism created from an urdf? For example, add a sphere to the last joint of a system. Can RigidBodyDynamics.attach! be used for this?

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## [read a .jxr file failed ](https://discourse.julialang.org/t/read-a-jxr-file-failed/17676)

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**Author:** [@zsz00](https://discourse.julialang.org/u/zsz00)\
**Replies:** 0\
**Last updated:** [November 18, 2018, 2:47pm UTC](https://discourse.julialang.org/t/read-a-jxr-file-failed/17676 "2018-11-18T14:47:38Z")

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read a .jxr file failed , what is wrong? using FileIO, ImageMagick; filename = "../test/matter/j0\_0.jxr" f1 = load(File(format"JXR", filename)) No FileIO.applicable\_loaders found for JXR

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## [\[ANN\] DandelionWebSockets.jl released for Julia 0.7 and 1.0](https://discourse.julialang.org/t/ann-dandelionwebsockets-jl-released-for-julia-0-7-and-1-0/17650)

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**Author:** [@erikedin](https://discourse.julialang.org/u/erikedin)\
**Replies:** 1\
**Last updated:** [November 18, 2018, 8:58am UTC](https://discourse.julialang.org/t/ann-dandelionwebsockets-jl-released-for-julia-0-7-and-1-0/17650 "2018-11-18T08:58:54Z")

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Hello! My WebSocket client DandelionWebSockets.jl is now released with v0.2.0, with Julia 0.7 and 1.0 compatibility. Some of the code was re-written and improved. The handshake code, which makes the connection, is stil…

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## [Multi-threading in Gurobi-JuMP Interface](https://discourse.julialang.org/t/multi-threading-in-gurobi-jump-interface/17626)

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**Author:** [@GabrielYin](https://discourse.julialang.org/u/GabrielYin)\
**Replies:** 4\
**Last updated:** [November 17, 2018, 11:46pm UTC](https://discourse.julialang.org/t/multi-threading-in-gurobi-jump-interface/17626 "2018-11-17T23:46:45Z")

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Hi there, I am a new Julia user in optimization usage, switched from GAMS and AMPL. I have tested some codes and they worked well. However, I would like to know how to set multi-threading in the Gurobi-JuMP interface. I…

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## [Discarding unused AffExpr](https://discourse.julialang.org/t/discarding-unused-affexpr/17634)

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**Author:** [@vtjeng](https://discourse.julialang.org/u/vtjeng)\
**Replies:** 1\
**Last updated:** [November 17, 2018, 3:44pm UTC](https://discourse.julialang.org/t/discarding-unused-affexpr/17634 "2018-11-17T15:44:31Z")

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As I’m creating my model in JuMP, I’m creating many AffExprs (~100k) but only a small fraction of them actually get used in constraints (I’m using interval arithmetic via ConditionalJuMP.jl to determine that the rest of …

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## [Trying to save a gif with Plots.jl results in an error](https://discourse.julialang.org/t/trying-to-save-a-gif-with-plots-jl-results-in-an-error/17620)

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**Author:** [@a-berg](https://discourse.julialang.org/u/a-berg)\
**Replies:** 1\
**Last updated:** [November 17, 2018, 10:37am UTC](https://discourse.julialang.org/t/trying-to-save-a-gif-with-plots-jl-results-in-an-error/17620 "2018-11-17T10:37:09Z")

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I’m not very experienced with julia yet and I wanted to create a gif for some animation. The animation is correctly created (using @animate macro) and I have manually checked that the 100 images are indeed created. How…

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## [Is anyone developing a SPA package like R/Shiny or Python/Dash?](https://discourse.julialang.org/t/is-anyone-developing-a-spa-package-like-r-shiny-or-python-dash/5733)

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**Author:** [@NickNack](https://discourse.julialang.org/u/NickNack)\
**Replies:** 28\
**Last updated:** [November 16, 2018, 9:09pm UTC](https://discourse.julialang.org/t/is-anyone-developing-a-spa-package-like-r-shiny-or-python-dash/5733 "2018-11-16T21:09:09Z")

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I’m working on a simple climate model that I would like to put online with some nice and friendly widgets. It would be a perfect fit for a Single Page Application, especially if Julia had a package that made this as simp…

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## [Multivariate logistic regression with interaction terms in Julia language](https://discourse.julialang.org/t/multivariate-logistic-regression-with-interaction-terms-in-julia-language/17611)

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**Author:** [@haley](https://discourse.julialang.org/u/haley)\
**Replies:** 1\
**Last updated:** [November 16, 2018, 9:04pm UTC](https://discourse.julialang.org/t/multivariate-logistic-regression-with-interaction-terms-in-julia-language/17611 "2018-11-16T21:04:22Z")

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Hello, I cannot find the answer to this question: Is is possible to learn logistic regression models of the form log(P / 1 - P) = a0 + a1 x1 + a2 x2 + a3 x3 + a12 x1 x2 + a13 x1 x3 + a23 x2 x3 + a123 x1 x2 x3? Thanks …

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## [Rotate a image](https://discourse.julialang.org/t/rotate-a-image/17586)

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**Author:** [@zsz00](https://discourse.julialang.org/u/zsz00)\
**Replies:** 10\
**Last updated:** [November 16, 2018, 4:03pm UTC](https://discourse.julialang.org/t/rotate-a-image/17586 "2018-11-16T16:03:05Z")

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I want to rotate a image with camara extri parameters matrix. but have error, can you help me amend it ? please!!! using Images, ImageFeatures, FileIO, ImageView using CoordinateTransformations, StaticArrays, Image…

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## [Odd slight perturbation in HypothesisTests](https://discourse.julialang.org/t/odd-slight-perturbation-in-hypothesistests/17582)

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**Author:** [@iwelch](https://discourse.julialang.org/u/iwelch)\
**Replies:** 5\
**Last updated:** [November 16, 2018, 3:42pm UTC](https://discourse.julialang.org/t/odd-slight-perturbation-in-hypothesistests/17582 "2018-11-16T15:42:22Z")

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julia\> using HypothesisTests, Random; julia\> Random.seed!(0); x= randn(100); y= randn(100); julia\> OneSampleTTest(x,y) the point estimate is slightly unstable. it may output one of the two: point estimate: …

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## [FWD: Request for Earth Science Informatics Proposals](https://discourse.julialang.org/t/fwd-request-for-earth-science-informatics-proposals/17591)

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**Author:** [@mauro3](https://discourse.julialang.org/u/mauro3)\
**Replies:** 0\
**Last updated:** [November 16, 2018, 8:17am UTC](https://discourse.julialang.org/t/fwd-request-for-earth-science-informatics-proposals/17591 "2018-11-16T08:17:31Z")

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Maybe of interest to someone here. I found an email advertising this in my inbox today (I’m in no way affiliated, I never even heard of them before): Request for Earth Science Informatics Incubator Proposals … projec…

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## [Strange behavior of \`mapreduce\`](https://discourse.julialang.org/t/strange-behavior-of-mapreduce/17588)

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**Author:** [@1115](https://discourse.julialang.org/u/1115)\
**Replies:** 2\
**Last updated:** [November 16, 2018, 7:49am UTC](https://discourse.julialang.org/t/strange-behavior-of-mapreduce/17588 "2018-11-16T07:49:11Z")

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I have a kernel, which uses the exp operation, it breaks down in a strange way Minimum working example: using CuArrays, CUDAnative CuArrays.allowscalar(false) x = randn(1000) |\> cu CUDAnative.map(CUDAnative.exp, x) CU…

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## [CUDAnative support for Float16](https://discourse.julialang.org/t/cudanative-support-for-float16/17369)

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**Author:** [@pedramz](https://discourse.julialang.org/u/pedramz)\
**Replies:** 5\
**Last updated:** [November 15, 2018, 10:19pm UTC](https://discourse.julialang.org/t/cudanative-support-for-float16/17369 "2018-11-15T22:19:44Z")

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I want to perform Float16 computation on GPU. In the vadd.jl example, when I change the rand function type from Float32 to Float16, the following error happens while running: ERROR: LoadError: InvalidIRError: compiling…

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## [How to time CUDA Event](https://discourse.julialang.org/t/how-to-time-cuda-event/17530)

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**Author:** [@cuchxq](https://discourse.julialang.org/u/cuchxq)\
**Replies:** 3\
**Last updated:** [November 15, 2018, 9:34pm UTC](https://discourse.julialang.org/t/how-to-time-cuda-event/17530 "2018-11-15T21:34:47Z")

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Hi, In CUDA C, you can time how long GPU ran by using event, this will record the time for just GPU running time, which does not include data transfer. Is there a similar functionality in CuArray or other GPU packages?

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## [Getting incremental cost for variables](https://discourse.julialang.org/t/getting-incremental-cost-for-variables/17563)

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**Author:** [@Rasoul](https://discourse.julialang.org/u/Rasoul)\
**Replies:** 1\
**Last updated:** [November 15, 2018, 4:09pm UTC](https://discourse.julialang.org/t/getting-incremental-cost-for-variables/17563 "2018-11-15T16:09:32Z")

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Can you please let me know how can I get incremental cost associated with variables after solving an optimization problem in Jump? Thanks in advance!

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## [Applicationerror: solver (gurobi) did not exit normally](https://discourse.julialang.org/t/applicationerror-solver-gurobi-did-not-exit-normally/17201)

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**Author:** [@Vondoe79](https://discourse.julialang.org/u/Vondoe79)\
**Replies:** 2\
**Last updated:** [November 14, 2018, 9:59pm UTC](https://discourse.julialang.org/t/applicationerror-solver-gurobi-did-not-exit-normally/17201 "2018-11-14T21:59:43Z")

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Hi there, I am getting this “applicationerror: solver (gurobi) did not exit normally”, the first time since using JuMP in 2 years. I have tried to look it up online, but no avail. Can anyone here please help me figure w…

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## [JuMP and user defined objective function: JuMPArray dimension problem](https://discourse.julialang.org/t/jump-and-user-defined-objective-function-jumparray-dimension-problem/17470)

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**Author:** [@axelle](https://discourse.julialang.org/u/axelle)\
**Replies:** 8\
**Last updated:** [November 14, 2018, 1:29pm UTC](https://discourse.julialang.org/t/jump-and-user-defined-objective-function-jumparray-dimension-problem/17470 "2018-11-14T13:29:37Z")

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Good afternoon, I had a look at previous topices on this subject and could not find the solution to my error. I have an optimization problem with a non linear user defined objective function called bk\_obj. This functio…

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## [cuArrays vs CUDANative](https://discourse.julialang.org/t/cuarrays-vs-cudanative/17504)

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**Author:** [@LaurentPlagne](https://discourse.julialang.org/u/LaurentPlagne)\
**Replies:** 3\
**Last updated:** [November 14, 2018, 12:38pm UTC](https://discourse.julialang.org/t/cuarrays-vs-cudanative/17504 "2018-11-14T12:38:01Z")

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Hi, From a 2D Array of floats b(nx,ny), I want to compute a(nx,ny-1) on the GPU as: function julia\_diff\_y(a,b) s=size(a) for j=1:s\[2\] for i=1:s\[1\] @inbounds a\[i,j\]=b\[i,j+1\]-b\[i,j\] en…

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## [Freeing memory in the GPU with CUDAdrv / CUDAnative / CuArrays](https://discourse.julialang.org/t/freeing-memory-in-the-gpu-with-cudadrv-cudanative-cuarrays/10946)

<div class="topic-metadata">

**Author:** [@una-dinosauria](https://discourse.julialang.org/u/una-dinosauria)\
**Replies:** 8\
**Last updated:** [November 13, 2018, 7:28pm UTC](https://discourse.julialang.org/t/freeing-memory-in-the-gpu-with-cudadrv-cudanative-cuarrays/10946 "2018-11-13T19:28:43Z")

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I am writing some code that calls CUDA kernels via CUDAdrv, allocates some CuArrays and uses a generic matrix addition (which I think is done via CUDAnative). The problem I have is that after I call this code a couple o…

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## [Making a struct definition available on the cluster](https://discourse.julialang.org/t/making-a-struct-definition-available-on-the-cluster/17460)

<div class="topic-metadata">

**Author:** [@rabarar](https://discourse.julialang.org/u/rabarar)\
**Replies:** 2\
**Last updated:** [November 13, 2018, 6:25pm UTC](https://discourse.julialang.org/t/making-a-struct-definition-available-on-the-cluster/17460 "2018-11-13T18:25:13Z")

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So I’m new to Julia - and I’ve been experimenting with the Distributed package - I wrote an example program to illustrate some of the concepts. Using remote channels, I can create primitive remote channel type, but how c…

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## [Flow "in" a Klein bottle](https://discourse.julialang.org/t/flow-in-a-klein-bottle/17475)

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**Author:** [@JeffreySarnoff](https://discourse.julialang.org/u/JeffreySarnoff)\
**Replies:** 3\
**Last updated:** [November 13, 2018, 6:07pm UTC](https://discourse.julialang.org/t/flow-in-a-klein-bottle/17475 "2018-11-13T18:07:04Z")

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Can we make something like this?

[Previous page](https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=516)

[Next page](https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=518)