# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=426

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**Page:** 427

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## [Websockets server with processed user input](https://discourse.julialang.org/t/websockets-server-with-processed-user-input/45360)

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**Author:** [@KirillGerke](https://discourse.julialang.org/u/KirillGerke)\
**Replies:** 0\
**Last updated:** [August 22, 2020, 10:55am UTC](https://discourse.julialang.org/t/websockets-server-with-processed-user-input/45360 "2020-08-22T10:55:32Z")

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Dear All, I am new to web-stack programming and my naive implementation of websockets server is not working. I took chat server (chat\_explore.jl) from WebSockets.jl examples here (chat\_explore.html is needed to run the …

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## [StackOverflowError trying to fit a difference equation with Turing](https://discourse.julialang.org/t/stackoverflowerror-trying-to-fit-a-difference-equation-with-turing/44349)

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**Author:** [@arnaudmgh](https://discourse.julialang.org/u/arnaudmgh)\
**Replies:** 7\
**Last updated:** [August 21, 2020, 11:21pm UTC](https://discourse.julialang.org/t/stackoverflowerror-trying-to-fit-a-difference-equation-with-turing/44349 "2020-08-21T23:21:51Z")

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I am trying to sample a difference equation using Turing but encounter errors. Basically, it’s a SIR model that solves fine, with a quick solver function written below (I wrote my own very simple solver to understand th…

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## [Scalar getindex during Flux gradient computation](https://discourse.julialang.org/t/scalar-getindex-during-flux-gradient-computation/45325)

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**Author:** [@HenriDeh](https://discourse.julialang.org/u/HenriDeh)\
**Replies:** 0\
**Last updated:** [August 21, 2020, 3:34pm UTC](https://discourse.julialang.org/t/scalar-getindex-during-flux-gradient-computation/45325 "2020-08-21T15:34:47Z")

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I have a issue with a GPU scalar getindex during gradient computation with Flux. Problem is, I just can’t reproduce the problem with a simpler MWE. I swear I tried so hard. So here’s a chunk of the code and what I unders…

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## [Smooth delta functions to compute Jacobian and Hessian from samples](https://discourse.julialang.org/t/smooth-delta-functions-to-compute-jacobian-and-hessian-from-samples/45282)

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**Author:** [@mleprovost](https://discourse.julialang.org/u/mleprovost)\
**Replies:** 10\
**Last updated:** [August 21, 2020, 10:16am UTC](https://discourse.julialang.org/t/smooth-delta-functions-to-compute-jacobian-and-hessian-from-samples/45282 "2020-08-21T10:16:18Z")

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Hello, Given an expensive function \\boldsymbol{G} :\\mathbb{R}^n \\xrightarrow{} \\mathbb{R}^m whose value is known at samples \\boldsymbol{x}^1,\\ldots, \\boldsymbol{x}^N, I would like to compute the Jacobian and Hessian a…

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## [Query.jl: collect's return type is not as expected](https://discourse.julialang.org/t/query-jl-collects-return-type-is-not-as-expected/45278)

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**Author:** [@kai](https://discourse.julialang.org/u/kai)\
**Replies:** 3\
**Last updated:** [August 21, 2020, 4:10am UTC](https://discourse.julialang.org/t/query-jl-collects-return-type-is-not-as-expected/45278 "2020-08-21T04:10:57Z")

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Hello, here’s something I don’t understand about Query.jl: After running a few query commands and calling collect, I was expecting the result to be of type Array{MyObs{Float64}, 1}, but got Array{MyObs,1} instead. When I…

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## [JuliaDB, dataframes: Speculations over the future of data packages](https://discourse.julialang.org/t/juliadb-dataframes-speculations-over-the-future-of-data-packages/14012)

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**Author:** [@DominiqueMakowski](https://discourse.julialang.org/u/DominiqueMakowski)\
**Replies:** 24\
**Last updated:** [August 21, 2020, 2:11am UTC](https://discourse.julialang.org/t/juliadb-dataframes-speculations-over-the-future-of-data-packages/14012 "2020-08-21T02:11:53Z")

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It is kinda unsettling for newcomers (at least those that are used to R or pandas) to see that there are different data-storage packages with the same goal, such as dataframes or JuliaDB, since many other packages depend…

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## [CUDA matmul performance](https://discourse.julialang.org/t/cuda-matmul-performance/45267)

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**Author:** [@acxz](https://discourse.julialang.org/u/acxz)\
**Replies:** 11\
**Last updated:** [August 21, 2020, 12:42am UTC](https://discourse.julialang.org/t/cuda-matmul-performance/45267 "2020-08-21T00:42:22Z")

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Hello everyone, I have recently been trying to GPUify my code. I first tried replacing my CPU Arrays with CuArrays as recommended, however, that resulted in a slower program execution time. So I’m trying to dig a bit d…

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## [Is there a Julia equivalent of scipy.optimize.minimize(method='TNC')?](https://discourse.julialang.org/t/is-there-a-julia-equivalent-of-scipy-optimize-minimize-method-tnc/45154)

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**Author:** [@liuyxpp](https://discourse.julialang.org/u/liuyxpp)\
**Replies:** 23\
**Last updated:** [August 21, 2020, 12:12am UTC](https://discourse.julialang.org/t/is-there-a-julia-equivalent-of-scipy-optimize-minimize-method-tnc/45154 "2020-08-21T00:12:52Z")

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which is a truncated Newton (TNC) algorithm, see here for details: minimize(method=’TNC’) — SciPy v1.9.1 Manual. I have a box constrained optimization problem which requires more evaluations with Optim.jl + BFGS (or any…

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## [Flux training GPU vs CPU different results](https://discourse.julialang.org/t/flux-training-gpu-vs-cpu-different-results/45165)

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**Author:** [@luboshanus](https://discourse.julialang.org/u/luboshanus)\
**Replies:** 7\
**Last updated:** [August 20, 2020, 8:19pm UTC](https://discourse.julialang.org/t/flux-training-gpu-vs-cpu-different-results/45165 "2020-08-20T20:19:02Z")

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Hi, I have a problem while training on GPU vs CPU. Or when I just once run train function it goes completely off while on GPU. If I choose CPU it just stays “converge” and not go further away. An example of 3 runs on GP…

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## [Elimination of Errors in JuMP model](https://discourse.julialang.org/t/elimination-of-errors-in-jump-model/45266)

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**Author:** [@mamo](https://discourse.julialang.org/u/mamo)\
**Replies:** 4\
**Last updated:** [August 20, 2020, 7:06pm UTC](https://discourse.julialang.org/t/elimination-of-errors-in-jump-model/45266 "2020-08-20T19:06:45Z")

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Give me suggestions for eliminating these errors please: LoadError: MethodError: no method matching getindex(::Tuple{Pair{String,Tuple{String,String}},Pair{String,NTuple{11,String}},Pair{String,Tuple{String,String,Strin…

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## [Poisson processes for many related univariate time series](https://discourse.julialang.org/t/poisson-processes-for-many-related-univariate-time-series/45211)

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**Author:** [@mystis](https://discourse.julialang.org/u/mystis)\
**Replies:** 4\
**Last updated:** [August 20, 2020, 4:19pm UTC](https://discourse.julialang.org/t/poisson-processes-for-many-related-univariate-time-series/45211 "2020-08-20T16:19:21Z")

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Hi everyone, I’ve been wanting to do some time series forecasting with Turing, because I’d like forecasting intervals as well. For practice, I’d like to forecast the norway car sales dataset. In short, it has ten years …

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## [A histogram that averages metadata instead of counts](https://discourse.julialang.org/t/a-histogram-that-averages-metadata-instead-of-counts/45257)

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**Author:** [@yakir12](https://discourse.julialang.org/u/yakir12)\
**Replies:** 6\
**Last updated:** [August 20, 2020, 12:59pm UTC](https://discourse.julialang.org/t/a-histogram-that-averages-metadata-instead-of-counts/45257 "2020-08-20T12:59:42Z")

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I have a bunch of coordinates and corresponding values: n = 100 xy = \[rand(2) for \_ in 1:n\] v = rand(n) I want to 2D-bin the coordinates, and calculate the mean of all the values, v, that fall into each corresponding b…

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## [Modifying arrays by views on workers](https://discourse.julialang.org/t/modifying-arrays-by-views-on-workers/45198)

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**Author:** [@tansongchen](https://discourse.julialang.org/u/tansongchen)\
**Replies:** 4\
**Last updated:** [August 20, 2020, 1:54am UTC](https://discourse.julialang.org/t/modifying-arrays-by-views-on-workers/45198 "2020-08-20T01:54:17Z")

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Julia has been good in my parallel computing works, however I encounter an issue recently. Let’s say I have an array a and I would like a @view as a shortcut to modify or refer to part of a, so I make a data structure ab…

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## [CUDA.jl tests on windows](https://discourse.julialang.org/t/cuda-jl-tests-on-windows/43378)

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**Author:** [@anj](https://discourse.julialang.org/u/anj)\
**Replies:** 25\
**Last updated:** [August 19, 2020, 7:48pm UTC](https://discourse.julialang.org/t/cuda-jl-tests-on-windows/43378 "2020-08-19T19:48:24Z")

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Trying to migrate to CUDA.jl. However can’t make tests passing (both with artifact download and local). Not 100% sure if this is a bug in CUDA.jl or I missed something. Any idea if tests meant to pass on Windows (I under…

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## [Ensemble simulations with "paired" trajectories](https://discourse.julialang.org/t/ensemble-simulations-with-paired-trajectories/45194)

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**Author:** [@Lachlan-Bn](https://discourse.julialang.org/u/Lachlan-Bn)\
**Replies:** 5\
**Last updated:** [August 19, 2020, 10:07am UTC](https://discourse.julialang.org/t/ensemble-simulations-with-paired-trajectories/45194 "2020-08-19T10:07:49Z")

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I’m interested in doing something roughly like the following: Choose a (possibly random) initial condition u0 From u0, take a (possibly random) “perturbation” of u0, say, x0 = u0 + s Integrate both trajectories, and ev…

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## [ApproxFun for vector-valued function](https://discourse.julialang.org/t/approxfun-for-vector-valued-function/45135)

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**Author:** [@mleprovost](https://discourse.julialang.org/u/mleprovost)\
**Replies:** 11\
**Last updated:** [August 19, 2020, 10:00am UTC](https://discourse.julialang.org/t/approxfun-for-vector-valued-function/45135 "2020-08-19T10:00:30Z")

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Hello, I have a vector-valued and nonlinear function f:\\mathbb{R}^n \\xrightarrow{} \\mathbb{R}^m with n, m \\sim 50. I am only interested in the local behavior of this function about a n-dimensional interval \[a\_1, b\_1\] \\…

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## [JuMP 0.21.1: CPLEX Error 1811: Attempt to invoke unsupported operation](https://discourse.julialang.org/t/jump-0-21-1-cplex-error-1811-attempt-to-invoke-unsupported-operation/36605)

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**Author:** [@mike\_k](https://discourse.julialang.org/u/mike_k)\
**Replies:** 8\
**Last updated:** [August 19, 2020, 9:31am UTC](https://discourse.julialang.org/t/jump-0-21-1-cplex-error-1811-attempt-to-invoke-unsupported-operation/36605 "2020-08-19T09:31:19Z")

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Dear folks, I try to add LazyConstaintCuts in a MIP model using MOI v0.9.12, CPLEX 12.9 (and it seems generic callbacks are used by default). After several cuts are added the solving procedure stops with the message in …

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## [Fancy indexing in ITensor](https://discourse.julialang.org/t/fancy-indexing-in-itensor/45201)

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**Author:** [@volkerkarle](https://discourse.julialang.org/u/volkerkarle)\
**Replies:** 0\
**Last updated:** [August 19, 2020, 9:21am UTC](https://discourse.julialang.org/t/fancy-indexing-in-itensor/45201 "2020-08-19T09:21:27Z")

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Hi folks, As I elaborated here, I think I just missed it in the docs of ITensor, but I do not see an easy way to do “fancy” indexing. Lets us consider the following example i = Index(10,"i") j = Index(20,"j") k = Index…

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## [Is it time to migrate to CUDA.jl?](https://discourse.julialang.org/t/is-it-time-to-migrate-to-cuda-jl/44203)

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**Author:** [@dfdx](https://discourse.julialang.org/u/dfdx)\
**Replies:** 10\
**Last updated:** [August 19, 2020, 6:01am UTC](https://discourse.julialang.org/t/is-it-time-to-migrate-to-cuda-jl/44203 "2020-08-19T06:01:10Z")

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From documentation of corresponding packages: CuArrays are deprecated in favor of CUDA.jl CUDA.jl only works on Julia 1.4 latest LTS version of Julia is 1.0 From these facts I conclude that the only way to keep backwa…

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## [Variable statement](https://discourse.julialang.org/t/variable-statement/45174)

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**Author:** [@mamo](https://discourse.julialang.org/u/mamo)\
**Replies:** 1\
**Last updated:** [August 18, 2020, 8:18pm UTC](https://discourse.julialang.org/t/variable-statement/45174 "2020-08-18T20:18:58Z")

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‘’‘@variable(model,PRDint\[o in O, f in F, p in P\[f\],j in U, t in TIME\], lower\_bound=0, upper\_bound=1000, Int)’‘’ ‘’‘@variable(model,PRD\[o in O,f in F, p in P\[f\], j in U, t in TIME, o\<=23 && f\<=13 && p\<=45\]==PRDint\[o,f,p…

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## [FreeCAD with Julia](https://discourse.julialang.org/t/freecad-with-julia/44966)

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**Author:** [@chakravala](https://discourse.julialang.org/u/chakravala)\
**Replies:** 10\
**Last updated:** [August 15, 2020, 4:16pm UTC](https://discourse.julialang.org/t/freecad-with-julia/44966 "2020-08-15T16:16:11Z")

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Looks like the FreeCAD community has taken an interest in supporting Julia computations: https://forum.freecadweb.org/viewtopic.php?f=8&t=42400

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## [Error: Unexpected values in bisection. (DifferentialEquations)](https://discourse.julialang.org/t/error-unexpected-values-in-bisection-differentialequations/45145)

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**Author:** [@Lachlan-Bn](https://discourse.julialang.org/u/Lachlan-Bn)\
**Replies:** 3\
**Last updated:** [August 18, 2020, 3:08pm UTC](https://discourse.julialang.org/t/error-unexpected-values-in-bisection-differentialequations/45145 "2020-08-18T15:08:02Z")

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I’m encountering an error related to using BigFloats and a callback that terminates the integrator upon certain conditions. More specifically, julia throws the following error when calling solve() with the callback on a …

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## [Difference between an ODE with manifold projection and a DAE](https://discourse.julialang.org/t/difference-between-an-ode-with-manifold-projection-and-a-dae/45136)

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**Author:** [@cuihantao](https://discourse.julialang.org/u/cuihantao)\
**Replies:** 3\
**Last updated:** [August 18, 2020, 1:08pm UTC](https://discourse.julialang.org/t/difference-between-an-ode-with-manifold-projection-and-a-dae/45136 "2020-08-18T13:08:40Z")

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Hi, I’d like to know the difference between an ODE set with manifold projection callback and a DAE (formulated as ODE with a singular mass matrix). It seems to me that the former one separates the algebraic equations fr…

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## [Quadratic and non-linear expressions cannot be mixed up!](https://discourse.julialang.org/t/quadratic-and-non-linear-expressions-cannot-be-mixed-up/45120)

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**Author:** [@musman](https://discourse.julialang.org/u/musman)\
**Replies:** 4\
**Last updated:** [August 18, 2020, 8:02am UTC](https://discourse.julialang.org/t/quadratic-and-non-linear-expressions-cannot-be-mixed-up/45120 "2020-08-18T08:02:12Z")

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Hi, I am setting up a non-linear objective which contains both quadratic and non-linear terms. However, I am getting the following error Unexpected quadratic expression 378.5346047250809 e\[1\]² + 378.5346047250809 f\[1\]² …

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## [Is there a MPI-based map package?](https://discourse.julialang.org/t/is-there-a-mpi-based-map-package/45087)

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**Author:** [@astrojhgu](https://discourse.julialang.org/u/astrojhgu)\
**Replies:** 2\
**Last updated:** [August 18, 2020, 4:14am UTC](https://discourse.julialang.org/t/is-there-a-mpi-based-map-package/45087 "2020-08-18T04:14:08Z")

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Is there such a package providing a function like? function mpi\_map(Function, Array, MPI\_COMM), which bechaviours like result=map(some\_input\_array, comm) do x some\_operation(x) done I wrote one myself based on se…

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## [Broadcast operations with multiple DenseAxisArrays are not yet supported](https://discourse.julialang.org/t/broadcast-operations-with-multiple-denseaxisarrays-are-not-yet-supported/45133)

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**Author:** [@zlq178](https://discourse.julialang.org/u/zlq178)\
**Replies:** 2\
**Last updated:** [August 18, 2020, 2:43am UTC](https://discourse.julialang.org/t/broadcast-operations-with-multiple-denseaxisarrays-are-not-yet-supported/45133 "2020-08-18T02:43:13Z")

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using JuMP,Gurobi n=4 a=\[0;0;50;50\] b=\[0;0;351;389\] c=\[0;0;44.4;40.6\] model=Model(Gurobi.Optimizer) @variable(model, P\[1:n,1\])#julia中创建一个全参数决策变量的方式 f=@expression(model,a'\*(P.\*P)+b'\*P+sum(c)) @objective(model,min,f) …

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## [Adding second order cone is slow](https://discourse.julialang.org/t/adding-second-order-cone-is-slow/45124)

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**Author:** [@sobhan](https://discourse.julialang.org/u/sobhan)\
**Replies:** 13\
**Last updated:** [August 18, 2020, 1:55am UTC](https://discourse.julialang.org/t/adding-second-order-cone-is-slow/45124 "2020-08-18T01:55:43Z")

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Hi, I have a conic model that i want to solve. The model looks like this using MathOptInterface const MOI = MathOptInterface using Gurobi using JuMP n=200 model = Model(Gurobi.Optimizer) @variable(model, t\[i=1:n, j=1:n…

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## [Stochastic MPC using JuMP - Explained in detail for future example in JuMP](https://discourse.julialang.org/t/stochastic-mpc-using-jump-explained-in-detail-for-future-example-in-jump/45100)

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**Author:** [@pandeysudan27](https://discourse.julialang.org/u/pandeysudan27)\
**Replies:** 2\
**Last updated:** [August 18, 2020, 12:23am UTC](https://discourse.julialang.org/t/stochastic-mpc-using-jump-explained-in-detail-for-future-example-in-jump/45100 "2020-08-18T00:23:10Z")

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I need help regarding formulating multi-state stochastic MPC in JuMP. In some way my optimization routine is wrong. Any help is much appreciated! swing MPC The swing equation is given as, M\\frac{d^2\\delta}{dt^2}=P\_\\mat…

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## [Conceptual Gaussian Process Questions](https://discourse.julialang.org/t/conceptual-gaussian-process-questions/44305)

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**Author:** [@nucklass](https://discourse.julialang.org/u/nucklass)\
**Replies:** 15\
**Last updated:** [August 17, 2020, 5:56pm UTC](https://discourse.julialang.org/t/conceptual-gaussian-process-questions/44305 "2020-08-17T17:56:26Z")

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Hi! This is more of a theoretical tangent, so forgive me if this is a bit off topic. I’ve recently finished my undergrad in Statistics and have been trying to navigate the US job market, to fairly dismal results. Anyway,…

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## [TextAnalysis.jl Naive Bayes Load Error](https://discourse.julialang.org/t/textanalysis-jl-naive-bayes-load-error/45115)

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**Author:** [@Chris\_Anderson](https://discourse.julialang.org/u/Chris_Anderson)\
**Replies:** 0\
**Last updated:** [August 17, 2020, 3:35pm UTC](https://discourse.julialang.org/t/textanalysis-jl-naive-bayes-load-error/45115 "2020-08-17T15:35:56Z")

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I am trying to use TextAnalysis.jl for some text classification using the Naive Bayes Classifier. However, I’ve been unable to begin as I’m getting an error before I can even load the classifier. using TextAnalysis: Nai…

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