# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?page=507

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**Page:** 508

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## [JuMP 19.0: constraint\_by\_name fails for vectorized constraints](https://discourse.julialang.org/t/jump-19-0-constraint-by-name-fails-for-vectorized-constraints/21481)

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**Author:** [@torgo](https://discourse.julialang.org/u/torgo)\
**Replies:** 6\
**Last updated:** [March 5, 2019, 6:15pm UTC](https://discourse.julialang.org/t/jump-19-0-constraint-by-name-fails-for-vectorized-constraints/21481 "2019-03-05T18:15:38Z")

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using JuMP m = Model() @variable(m, x\[1:2\]) @constraint(m, mycons, x .== 0) cn = constraint\_by\_name(m, "mycons") # returns nothing Should cn be nothing? I expected it would return an array of constraint references.

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## [Makie hypersphere with radius other than 1?](https://discourse.julialang.org/t/makie-hypersphere-with-radius-other-than-1/21460)

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**Author:** [@kmhaeren](https://discourse.julialang.org/u/kmhaeren)\
**Replies:** 3\
**Last updated:** [March 5, 2019, 5:12pm UTC](https://discourse.julialang.org/t/makie-hypersphere-with-radius-other-than-1/21460 "2019-03-05T17:12:47Z")

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Hi I’m using Makie to display a physics engine, and I’m trying to draw 3D spheres of different radii, however, when I try to display “Sphere(Point3(0),5)” for example, it still shows a sphere with a radius of 1. I look…

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## [Boundaries for @NLparameters](https://discourse.julialang.org/t/boundaries-for-nlparameters/21490)

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**Author:** [@tamasgal](https://discourse.julialang.org/u/tamasgal)\
**Replies:** 4\
**Last updated:** [March 5, 2019, 1:47pm UTC](https://discourse.julialang.org/t/boundaries-for-nlparameters/21490 "2019-03-05T13:47:43Z")

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I am currently discovering the world of JuMP.jl and I have to say, I am amazed, thanks for this package! TL;DR: how do I add constraints or limits to parameters which are not defined by @variable but @NLparameter? Full…

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## [State of reverse mode AD tools](https://discourse.julialang.org/t/state-of-reverse-mode-ad-tools/21467)

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**Author:** [@Tamas\_Papp](https://discourse.julialang.org/u/Tamas_Papp)\
**Replies:** 8\
**Last updated:** [March 5, 2019, 10:51am UTC](https://discourse.julialang.org/t/state-of-reverse-mode-ad-tools/21467 "2019-03-05T10:51:09Z")

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(Opening a new topic instead of resurrecting some older ones.) I am wondering about the current state of libraries for reverse mode AD, specifically for differentiating \\mathbb{R}^n \\to \\mathbb{R} functions that accep…

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## [Bug? Using Flux & getting Float32 response on 64 bit Ubuntu OS](https://discourse.julialang.org/t/bug-using-flux-getting-float32-response-on-64-bit-ubuntu-os/21440)

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**Author:** [@samq](https://discourse.julialang.org/u/samq)\
**Replies:** 4\
**Last updated:** [March 4, 2019, 6:53pm UTC](https://discourse.julialang.org/t/bug-using-flux-getting-float32-response-on-64-bit-ubuntu-os/21440 "2019-03-04T18:53:25Z")

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Julia version 1.1.0 Ubuntu 16.04 64 bit Flux version (?) please tell me how to see the version of Flux I get Float32 responses instead of Float64 when doing the following: using Flux model = Flux.Dense(2, 1, σ) mod…

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## [Example of simple 1 layer Perception in Flux](https://discourse.julialang.org/t/example-of-simple-1-layer-perception-in-flux/21413)

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**Author:** [@samq](https://discourse.julialang.org/u/samq)\
**Replies:** 8\
**Last updated:** [March 4, 2019, 6:38pm UTC](https://discourse.julialang.org/t/example-of-simple-1-layer-perception-in-flux/21413 "2019-03-04T18:38:33Z")

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I saw the Flux pages, but the examples are not clear to me. Since Flux is simple and fast, would someone please post an example of how to make a simple 1 layer Perceptron using Flux? Such an example would be a springbo…

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## [Adding CPLEX callbacks with JuMP v0.19](https://discourse.julialang.org/t/adding-cplex-callbacks-with-jump-v0-19/21449)

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**Author:** [@mike\_k](https://discourse.julialang.org/u/mike_k)\
**Replies:** 7\
**Last updated:** [March 4, 2019, 3:28pm UTC](https://discourse.julialang.org/t/adding-cplex-callbacks-with-jump-v0-19/21449 "2019-03-04T15:28:14Z")

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Dear community, I use CPLEX 12.8 and made an update from JuMP v18.5 to v0.19. Due to major changes in the new version I have to adapt my code, and I do not succeed to add callbacks. The release notes say that callbacks …

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## [A Qubit DSL?](https://discourse.julialang.org/t/a-qubit-dsl/8599)

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**Author:** [@grant](https://discourse.julialang.org/u/grant)\
**Replies:** 50\
**Last updated:** [March 4, 2019, 2:28pm UTC](https://discourse.julialang.org/t/a-qubit-dsl/8599 "2019-03-04T14:28:48Z")

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I have a general question, is it possible to design a DSL using Dirac’s bra ket notation? It seems that |\> is already used in the language, which corresponds to kets, so I’m not sure what the possibilities are. For exam…

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## [Unexpected? result of multiplication with adjoint()](https://discourse.julialang.org/t/unexpected-result-of-multiplication-with-adjoint/21447)

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**Author:** [@ivanslapnicar](https://discourse.julialang.org/u/ivanslapnicar)\
**Replies:** 1\
**Last updated:** [March 4, 2019, 12:20pm UTC](https://discourse.julialang.org/t/unexpected-result-of-multiplication-with-adjoint/21447 "2019-03-04T12:20:25Z")

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On Julia Version 1.0.2 the output of the following code using LinearAlgebra unblock(A) = mapreduce(identity, hcat, \[mapreduce(identity, vcat, A\[:,i\]) for i = 1:size(A,2)\]) x=Vector{Any}(undef,2) x\[1\]=\[1+2im 1-im;-3 4+3i…

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## [Why Julia machine learning is so unfriendly? Very "unsmooth" experience from foolish guy](https://discourse.julialang.org/t/why-julia-machine-learning-is-so-unfriendly-very-unsmooth-experience-from-foolish-guy/21174)

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**Author:** [@kirtsar](https://discourse.julialang.org/u/kirtsar)\
**Replies:** 15\
**Last updated:** [March 3, 2019, 4:19pm UTC](https://discourse.julialang.org/t/why-julia-machine-learning-is-so-unfriendly-very-unsmooth-experience-from-foolish-guy/21174 "2019-03-03T16:19:01Z")

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Ok, so let’s imagine that I’m a newcomer in a field of machine learning, and the very first task i want to do in Julia is something like knn-classifier. Nice! So let’s try to do it step by step, using all those cool libr…

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## [JuliaDB: How to find the number of rows and columns?](https://discourse.julialang.org/t/juliadb-how-to-find-the-number-of-rows-and-columns/21406)

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**Author:** [@xiaodai](https://discourse.julialang.org/u/xiaodai)\
**Replies:** 1\
**Last updated:** [March 3, 2019, 2:11am UTC](https://discourse.julialang.org/t/juliadb-how-to-find-the-number-of-rows-and-columns/21406 "2019-03-03T02:11:31Z")

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I loaded a JuliaDB table, but how do I find the number of rows and columns? size doesn’t work.

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## [\[DiffEqFlux\] How to do composition of layers?](https://discourse.julialang.org/t/diffeqflux-how-to-do-composition-of-layers/21291)

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**Author:** [@pochoi](https://discourse.julialang.org/u/pochoi)\
**Replies:** 4\
**Last updated:** [March 2, 2019, 10:16pm UTC](https://discourse.julialang.org/t/diffeqflux-how-to-do-composition-of-layers/21291 "2019-03-02T22:16:03Z")

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How to do composition of layers in DiffEqFlux? For example, I want do composite a layer of neural ODE with a layer of NN: dudt = Chain(Dense(2,40,tanh), Dense(40,2)) tspan = (0.0f0,1.0f0) t = range(tspan\[1\],tspan\[2\],le…

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## [Out-of-core MUMPS.jl Implementation](https://discourse.julialang.org/t/out-of-core-mumps-jl-implementation/21372)

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**Author:** [@Uche](https://discourse.julialang.org/u/Uche)\
**Replies:** 1\
**Last updated:** [March 2, 2019, 6:27pm UTC](https://discourse.julialang.org/t/out-of-core-mumps-jl-implementation/21372 "2019-03-02T18:27:48Z")

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So how does the out-of-core MUMPS.jl work? Is there any specific thing a user should do to use this option? Thanks. Uche.

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## [Parallel calls to build-in functions](https://discourse.julialang.org/t/parallel-calls-to-build-in-functions/21300)

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**Author:** [@stakaz](https://discourse.julialang.org/u/stakaz)\
**Replies:** 4\
**Last updated:** [March 2, 2019, 5:23pm UTC](https://discourse.julialang.org/t/parallel-calls-to-build-in-functions/21300 "2019-03-02T17:23:23Z")

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Hello, I am not new to julia but until now never was forced to do any parallel computations with it. Now, I have a simple case where I want to use Thread or Processes to speed up the computations but I don’t really see …

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## [Understanding BigInt](https://discourse.julialang.org/t/understanding-bigint/21337)

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**Author:** [@johnh](https://discourse.julialang.org/u/johnh)\
**Replies:** 3\
**Last updated:** [March 1, 2019, 11:46am UTC](https://discourse.julialang.org/t/understanding-bigint/21337 "2019-03-01T11:46:49Z")

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Playing aroudn with types yesterday I found typemax(BigInt) does not exist. Which makes perfect sense. the Julia documentation on Arbitrary Precision Arithmetic refers to the Gnu GMP. Would this be the best place to rea…

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## [Engarde - Python defensive data analysis](https://discourse.julialang.org/t/engarde-python-defensive-data-analysis/21334)

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**Author:** [@johnh](https://discourse.julialang.org/u/johnh)\
**Replies:** 3\
**Last updated:** [March 1, 2019, 10:42am UTC](https://discourse.julialang.org/t/engarde-python-defensive-data-analysis/21334 "2019-03-01T10:42:56Z")

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I went to a Meet up o data engineering at https://www.quantumblack.com/ Engarde was mentioned: Engarde! — engarde 0.4.0+9.ge7ea040 documentation Looks very useful. Is there anything similar in Julia?

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## [Rounding to a multiple of float](https://discourse.julialang.org/t/rounding-to-a-multiple-of-float/21295)

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**Author:** [@cedeerwe](https://discourse.julialang.org/u/cedeerwe)\
**Replies:** 25\
**Last updated:** [February 28, 2019, 9:52pm UTC](https://discourse.julialang.org/t/rounding-to-a-multiple-of-float/21295 "2019-02-28T21:52:22Z")

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I am trying to solve a simple problem - rounding a number to a nearest multiple of a given float. As an example, I would like roundmult(3811.47123123, 0.01) = 3811.47. However, the simplest implementation of roundmult(va…

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## [Parallel Computations](https://discourse.julialang.org/t/parallel-computations/21070)

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**Author:** [@ennvvy](https://discourse.julialang.org/u/ennvvy)\
**Replies:** 6\
**Last updated:** [February 22, 2019, 2:07pm UTC](https://discourse.julialang.org/t/parallel-computations/21070 "2019-02-22T14:07:54Z")

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I have migrated to Julia very recently. To be able to lower computation time, I have been trying to implement parallel programming concepts in my serial code. @time begin @everywhere N = 100 ; @everywhere agents = co…

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## [DiffEqFlux: how do declare a system of ODE which is backpropagatable?](https://discourse.julialang.org/t/diffeqflux-how-do-declare-a-system-of-ode-which-is-backpropagatable/21254)

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**Author:** [@pochoi](https://discourse.julialang.org/u/pochoi)\
**Replies:** 2\
**Last updated:** [February 28, 2019, 5:58am UTC](https://discourse.julialang.org/t/diffeqflux-how-do-declare-a-system-of-ode-which-is-backpropagatable/21254 "2019-02-28T05:58:38Z")

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Here is a simple example. Flux’s parameter seems to be not so friendly with matrix multiplication. When doing p .\* A where p is a parameter and A is a matrix, things go bad… using DifferentialEquations using Flux, Dif…

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## [\[solved\] Can't install MPI.jl in julia 1.0.1/0.7.0 on a CENTOS 7.4](https://discourse.julialang.org/t/solved-cant-install-mpi-jl-in-julia-1-0-1-0-7-0-on-a-centos-7-4/16532)

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**Author:** [@GM\_44](https://discourse.julialang.org/u/GM_44)\
**Replies:** 13\
**Last updated:** [February 28, 2019, 12:47am UTC](https://discourse.julialang.org/t/solved-cant-install-mpi-jl-in-julia-1-0-1-0-7-0-on-a-centos-7-4/16532 "2019-02-28T00:47:19Z")

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Hello, I’m new to Julia. I hope this post is at the right place. So, I have to install MPI.jl module for one of our users. It doesn’t work. I have installed Linux 64 bits binary versions of julia 0.7.0 and 1.0.1 julia…

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## [Is there any microsimulation package in Julia?](https://discourse.julialang.org/t/is-there-any-microsimulation-package-in-julia/20049)

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**Author:** [@sbacelar](https://discourse.julialang.org/u/sbacelar)\
**Replies:** 4\
**Last updated:** [February 27, 2019, 11:26pm UTC](https://discourse.julialang.org/t/is-there-any-microsimulation-package-in-julia/20049 "2019-02-27T23:26:08Z")

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Something along the lines of LIAM2 in Python or MicSim in R.

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## [Group KFold?](https://discourse.julialang.org/t/group-kfold/21165)

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**Author:** [@charlesll](https://discourse.julialang.org/u/charlesll)\
**Replies:** 4\
**Last updated:** [February 27, 2019, 10:30pm UTC](https://discourse.julialang.org/t/group-kfold/21165 "2019-02-27T22:30:46Z")

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Hi, I am trying to implement a Group KFold function for my problem, where I need to slit the dataset as a function of some label. There is no function like that in MLDataUtils or MLbase to my knowledge, so I am trying …

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## [Flux.jl and the state of multi-processing](https://discourse.julialang.org/t/flux-jl-and-the-state-of-multi-processing/21170)

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**Author:** [@Alexander-Barth](https://discourse.julialang.org/u/Alexander-Barth)\
**Replies:** 2\
**Last updated:** [February 27, 2019, 7:51am UTC](https://discourse.julialang.org/t/flux-jl-and-the-state-of-multi-processing/21170 "2019-02-27T07:51:56Z")

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I try to implement a convolutional auto encoder in Flux. The model is composed essentially of several convolutional layers, max pool, interpolation to the nearest neighborhood (using repeat(...; inner = (2,2,1,1)). The …

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## [JuMP uses all available memory, can't do anything else after](https://discourse.julialang.org/t/jump-uses-all-available-memory-cant-do-anything-else-after/21238)

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**Author:** [@cosmia](https://discourse.julialang.org/u/cosmia)\
**Replies:** 1\
**Last updated:** [February 27, 2019, 7:50am UTC](https://discourse.julialang.org/t/jump-uses-all-available-memory-cant-do-anything-else-after/21238 "2019-02-27T07:50:04Z")

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Hey guys, so I have an optimization problem in which JuMP with Ipopt uses 90% of my available RAM memory for automatic differentiation. In my layman’s understanding, after it calculates the hessian and all, it stores it…

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## [Strange behavior inside a for-loop with ArrayFire](https://discourse.julialang.org/t/strange-behavior-inside-a-for-loop-with-arrayfire/21187)

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**Author:** [@Noel\_Araujo](https://discourse.julialang.org/u/Noel_Araujo)\
**Replies:** 3\
**Last updated:** [February 26, 2019, 4:58pm UTC](https://discourse.julialang.org/t/strange-behavior-inside-a-for-loop-with-arrayfire/21187 "2019-02-26T16:58:50Z")

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Hello everyone, I have a issue and I don’t even know the exactly cause. I am using ArrayFire to speed up some matrix multiplications. However, I cannot retrieve the data unless I do some useless operation into my data. …

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## [Some trick in NLconstraint to avoid NaN or Inf for zero initial condition ?](https://discourse.julialang.org/t/some-trick-in-nlconstraint-to-avoid-nan-or-inf-for-zero-initial-condition/9831)

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**Author:** [@cfrodriguez](https://discourse.julialang.org/u/cfrodriguez)\
**Replies:** 3\
**Last updated:** [February 26, 2019, 2:33pm UTC](https://discourse.julialang.org/t/some-trick-in-nlconstraint-to-avoid-nan-or-inf-for-zero-initial-condition/9831 "2019-02-26T14:33:57Z")

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Hello all, I am new using JuMP. In my code, I added a thermodynamic model (UNIQUAC). When xNT1 = 0.001 it work well. But when the value is almost zero (1e-11) it doesn’t work and JuMP give me “Warning: Cutting back alph…

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## [Using CUSOLVER in CuArrays.jl](https://discourse.julialang.org/t/using-cusolver-in-cuarrays-jl/21020)

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**Author:** [@eliassno](https://discourse.julialang.org/u/eliassno)\
**Replies:** 12\
**Last updated:** [February 26, 2019, 2:21pm UTC](https://discourse.julialang.org/t/using-cusolver-in-cuarrays-jl/21020 "2019-02-26T14:21:35Z")

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I’m writing a GPU-version of gesv!, using CuArrays.jl. The following works: using CuArrays, LinearAlgebra, Test function gpugesv!(A,b) A, ipiv = CuArrays.CUSOLVER.getrf!(A) CuArrays.CUSOLVER.getrs!('N'…

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## [Smallest Eigenvalue of a Moler Matrix \[Again\]](https://discourse.julialang.org/t/smallest-eigenvalue-of-a-moler-matrix-again/21112)

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**Author:** [@Hans\_W\_Borchers](https://discourse.julialang.org/u/Hans_W_Borchers)\
**Replies:** 6\
**Last updated:** [February 26, 2019, 12:43pm UTC](https://discourse.julialang.org/t/smallest-eigenvalue-of-a-moler-matrix-again/21112 "2019-02-26T12:43:12Z")

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I am referring to help I received from Andreas Noack 10 months ago. https://discourse.julialang.org/t/smallest-eigenvalue-of-a-moler-matrix/10510 I wanted to compute the smallest eigenvalue of Moler matrices with high …

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## [Flux not able to resolve strong observation, based on standard example that works](https://discourse.julialang.org/t/flux-not-able-to-resolve-strong-observation-based-on-standard-example-that-works/21177)

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**Author:** [@ianshmean](https://discourse.julialang.org/u/ianshmean)\
**Replies:** 2\
**Last updated:** [February 25, 2019, 6:09pm UTC](https://discourse.julialang.org/t/flux-not-able-to-resolve-strong-observation-based-on-standard-example-that-works/21177 "2019-02-25T18:09:14Z")

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I don’t understand why the housing example found here, which functions as expected, is not able to train on alternative data where I’m intentionally including the target in the observations to make it really easy. using…

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## ["A Comparison of Three Programming Languages for a Full-Fledged Next-Generation Sequencing Tool" selects...Go?](https://discourse.julialang.org/t/a-comparison-of-three-programming-languages-for-a-full-fledged-next-generation-sequencing-tool-selects-go/21126)

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**Author:** [@jballanc](https://discourse.julialang.org/u/jballanc)\
**Replies:** 5\
**Last updated:** [February 25, 2019, 5:40pm UTC](https://discourse.julialang.org/t/a-comparison-of-three-programming-languages-for-a-full-fledged-next-generation-sequencing-tool-selects-go/21126 "2019-02-25T17:40:09Z")

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Was wondering if anyone has had a chance to look at this paper posted to bioRxiv yesterday? I’ve only just briefly skimmed the paper and associated code, but I find the results…interesting. The authors appear to have tak…

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