# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=392

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**Page:** 393

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## [Existing package for basic mesh manipulation?](https://discourse.julialang.org/t/existing-package-for-basic-mesh-manipulation/53941)

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**Author:** [@OliverEvans96](https://discourse.julialang.org/u/OliverEvans96)\
**Replies:** 16\
**Last updated:** [January 31, 2021, 12:13am UTC](https://discourse.julialang.org/t/existing-package-for-basic-mesh-manipulation/53941 "2021-01-31T00:13:18Z")

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Hi all, Just a quick question: is there a package out there that I can use to perform basic mesh manipulations such as subdivide, extrude, etc.? I see Meshes.jl, which has some triangulation functions, but I don’t see m…

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## [CUDA.jl not inlining "simple" functions](https://discourse.julialang.org/t/cuda-jl-not-inlining-simple-functions/50153)

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**Author:** [@cdsousa](https://discourse.julialang.org/u/cdsousa)\
**Replies:** 5\
**Last updated:** [January 30, 2021, 7:11pm UTC](https://discourse.julialang.org/t/cuda-jl-not-inlining-simple-functions/50153 "2021-01-30T19:11:04Z")

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After porting some code from using oneAPI.jl GPU kernels to CUDA.jl I got timings in CUDA which were higher than the ones from running in an Intel GPU. Something like getting 20ms on the on an Nvidia Gtx 1080 Ti and 14m…

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## [Soss updates](https://discourse.julialang.org/t/soss-updates/53362)

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**Author:** [@cscherrer](https://discourse.julialang.org/u/cscherrer)\
**Replies:** 6\
**Last updated:** [January 30, 2021, 4:28pm UTC](https://discourse.julialang.org/t/soss-updates/53362 "2021-01-30T16:28:26Z")

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Hello all, Just thought I’d talk a bit about the latest with Soss. Everything here is from the Soss, MeasureTheory, NestedTuples, and SymbolicCodegen packages. An easy problem Say we have a simple model with some obser…

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## [Brusselator and Catalyst](https://discourse.julialang.org/t/brusselator-and-catalyst/54222)

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**Author:** [@aquarelleX332](https://discourse.julialang.org/u/aquarelleX332)\
**Replies:** 3\
**Last updated:** [January 30, 2021, 1:38pm UTC](https://discourse.julialang.org/t/brusselator-and-catalyst/54222 "2021-01-30T13:38:27Z")

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Good evening to all, I recently solved the ODEs system for the brusselator: A -\> X (k1) 2X + Y -\> 3X (k2) B + X -\> Y + D (k3) X -\> E (k4) where A, B, etc are chemical species and k represents kinetics coefficients. B…

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## [NLopt stalls without objective progress?](https://discourse.julialang.org/t/nlopt-stalls-without-objective-progress/54073)

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**Author:** [@evanfields](https://discourse.julialang.org/u/evanfields)\
**Replies:** 2\
**Last updated:** [January 30, 2021, 1:13pm UTC](https://discourse.julialang.org/t/nlopt-stalls-without-objective-progress/54073 "2021-01-30T13:13:58Z")

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I have an optimization problem which I’m solving with NLopt (algorithm :LD\_MMA). The objective is nonlinear, there are upper/lower bound constraints, and one linear constraint. It seems like no matter how long I let NLop…

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## [Registering an array of functions and using them in constraints and objectives](https://discourse.julialang.org/t/registering-an-array-of-functions-and-using-them-in-constraints-and-objectives/53294)

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**Author:** [@maajdl](https://discourse.julialang.org/u/maajdl)\
**Replies:** 4\
**Last updated:** [January 30, 2021, 8:40am UTC](https://discourse.julialang.org/t/registering-an-array-of-functions-and-using-them-in-constraints-and-objectives/53294 "2021-01-30T08:40:43Z")

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(Julia beginner) Still thinking about Nonlinear Programming with JuMP with some generality. (@NLconstraint with a sum, array and scalar variables) There are many NLP JuMP examples available but all more or less simila…

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## [Optimization with JuMP: an affine expression enters a nonlinear constraint (dynamic discrete choice)](https://discourse.julialang.org/t/optimization-with-jump-an-affine-expression-enters-a-nonlinear-constraint-dynamic-discrete-choice/54230)

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**Author:** [@kwokhao](https://discourse.julialang.org/u/kwokhao)\
**Replies:** 2\
**Last updated:** [January 30, 2021, 12:14am UTC](https://discourse.julialang.org/t/optimization-with-jump-an-affine-expression-enters-a-nonlinear-constraint-dynamic-discrete-choice/54230 "2021-01-30T00:14:10Z")

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I am trying to use JuMP to solve a dynamic programming problem, but I cannot get MPEC (with Ipopt) to work. I am solving a prediction problem. There are 2 products, “safe” and “risky”. The safe product always yields uti…

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## [MethodError: no method matching isless(::Int64, ::Array{UnitRange{Int64},1})](https://discourse.julialang.org/t/methoderror-no-method-matching-isless-int64-array-unitrange-int64-1/53970)

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**Author:** [@GraceMabele](https://discourse.julialang.org/u/GraceMabele)\
**Replies:** 20\
**Last updated:** [January 29, 2021, 4:45pm UTC](https://discourse.julialang.org/t/methoderror-no-method-matching-isless-int64-array-unitrange-int64-1/53970 "2021-01-29T16:45:43Z")

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Hi I am a newbie to JuMP(Julia) and coding too, I am currently computing the following constraints in code below however, it is returning the following error and I am not exactly sure how to solve and I do not understan…

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## [One colorbar for all subplots using cartopy mapping via PyCall](https://discourse.julialang.org/t/one-colorbar-for-all-subplots-using-cartopy-mapping-via-pycall/54134)

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**Author:** [@EuRoXy](https://discourse.julialang.org/u/EuRoXy)\
**Replies:** 6\
**Last updated:** [January 29, 2021, 4:16pm UTC](https://discourse.julialang.org/t/one-colorbar-for-all-subplots-using-cartopy-mapping-via-pycall/54134 "2021-01-29T16:16:04Z")

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I try to generate a shared colorbar for several subplots using cartopy via PyCall and PyPlot but haven’t succeeded. Here’s a minimal code example with separate colorbars: using PyCall, PyPlot plt = pyimport("matplotlib…

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## [Packages for Drawing and Graphics](https://discourse.julialang.org/t/packages-for-drawing-and-graphics/54153)

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**Author:** [@brett\_knoss](https://discourse.julialang.org/u/brett_knoss)\
**Replies:** 14\
**Last updated:** [January 29, 2021, 4:14pm UTC](https://discourse.julialang.org/t/packages-for-drawing-and-graphics/54153 "2021-01-29T16:14:12Z")

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What packages do I use for graphics? I found Cairo.jl and Graphics.jl the latter says it uses the former as a backend, but Graphics.jl is missing a lot of docstrings and looks abandoned.

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## [Make transparent square in Gadfly](https://discourse.julialang.org/t/make-transparent-square-in-gadfly/54116)

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**Author:** [@fredih](https://discourse.julialang.org/u/fredih)\
**Replies:** 4\
**Last updated:** [January 29, 2021, 12:54pm UTC](https://discourse.julialang.org/t/make-transparent-square-in-gadfly/54116 "2021-01-29T12:54:07Z")

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I want to plot a transparent square over certain time ranges in the Gantt chart @Mattriks created here. It looks like this: And I want it to look somtehing like this: How could I do it?

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## [Importance of offset](https://discourse.julialang.org/t/importance-of-offset/54170)

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**Author:** [@Ruchitha\_Kumar](https://discourse.julialang.org/u/Ruchitha_Kumar)\
**Replies:** 3\
**Last updated:** [January 29, 2021, 10:54am UTC](https://discourse.julialang.org/t/importance-of-offset/54170 "2021-01-29T10:54:07Z")

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What does the offset 20 signify in the below code? using ModelingToolkit @variables x y z @parameters a b c ----Define a nonlinear system eqs = \[0 ~ - y - (z+20), 0 ~ x + a \* y, 0 ~ b + (z+20) \* (x - c)\] ns = Non…

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## [Obtaining variable scalar coefficients in objective](https://discourse.julialang.org/t/obtaining-variable-scalar-coefficients-in-objective/54128)

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**Author:** [@gobs](https://discourse.julialang.org/u/gobs)\
**Replies:** 2\
**Last updated:** [January 29, 2021, 7:59am UTC](https://discourse.julialang.org/t/obtaining-variable-scalar-coefficients-in-objective/54128 "2021-01-29T07:59:37Z")

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Hello! I would like to extend NREL’s progressive hedging package to include a scaled penalty parameter, i.e. one which is proportional to the coefficients of the variable being penalised in the objective function. Long …

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## [JuMP 0.21.6 released](https://discourse.julialang.org/t/jump-0-21-6-released/54161)

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**Author:** [@odow](https://discourse.julialang.org/u/odow)\
**Replies:** 0\
**Last updated:** [January 29, 2021, 5:10am UTC](https://discourse.julialang.org/t/jump-0-21-6-released/54161 "2021-01-29T05:10:20Z")

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Dear all, We are pleased to announce the release of JuMP 0.21.6. You can find more information about the release on our blog: JuMP 0.21.6 is released | JuMP. The major change for most users is that we have over-hauled …

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## [Gurobi how to get variable coefficients in constraints](https://discourse.julialang.org/t/gurobi-how-to-get-variable-coefficients-in-constraints/54150)

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**Author:** [@rezabayani](https://discourse.julialang.org/u/rezabayani)\
**Replies:** 5\
**Last updated:** [January 29, 2021, 3:51am UTC](https://discourse.julialang.org/t/gurobi-how-to-get-variable-coefficients-in-constraints/54150 "2021-01-29T03:51:56Z")

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I am trying to extract the variable coefficients in a constraint. According to Gurobi documentation, https://www.gurobi.com/documentation/9.1/refman/py\_model\_getcoeff.html, the function Model.getCoeff() should do the tri…

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## [Attempted to port an RL algorithm from PyTorch to Flux and it's 10x slower](https://discourse.julialang.org/t/attempted-to-port-an-rl-algorithm-from-pytorch-to-flux-and-its-10x-slower/54036)

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**Author:** [@DevJac](https://discourse.julialang.org/u/DevJac)\
**Replies:** 17\
**Last updated:** [January 29, 2021, 2:08am UTC](https://discourse.julialang.org/t/attempted-to-port-an-rl-algorithm-from-pytorch-to-flux-and-its-10x-slower/54036 "2021-01-29T02:08:29Z")

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I ported an algorithm described in the book Grokking Deep Reinforcement Learning (which I recommend if you’re a beginner to RL) from PyTorch to Julia. This algorithm is described in chapter 8 of the book, and it is meant…

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## [Query.jl - User-set missing values in data frames not removed by @dropna](https://discourse.julialang.org/t/query-jl-user-set-missing-values-in-data-frames-not-removed-by-dropna/54094)

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**Author:** [@danvinci](https://discourse.julialang.org/u/danvinci)\
**Replies:** 2\
**Last updated:** [January 28, 2021, 2:13pm UTC](https://discourse.julialang.org/t/query-jl-user-set-missing-values-in-data-frames-not-removed-by-dropna/54094 "2021-01-28T14:13:42Z")

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Hi everyone! I’m new to Julia and trying to learn how to use the Query package with data frames, and this question/issue is specific to it. I’m running into the following issue: after importing some CSV data, I need t…

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## [Three state variable](https://discourse.julialang.org/t/three-state-variable/53632)

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**Author:** [@user1200](https://discourse.julialang.org/u/user1200)\
**Replies:** 10\
**Last updated:** [January 28, 2021, 9:56pm UTC](https://discourse.julialang.org/t/three-state-variable/53632 "2021-01-28T21:56:07Z")

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Edit1: Sorry i found lens next to avatar ^^ Hello Please can I ask newbie q, i need to make signum variable from another variable. (tried things like type Int in variable type / sign function in constrains but get err…

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## [Zygote differentiation issues](https://discourse.julialang.org/t/zygote-differentiation-issues/54130)

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**Author:** [@adhikarirsr](https://discourse.julialang.org/u/adhikarirsr)\
**Replies:** 7\
**Last updated:** [January 28, 2021, 8:12pm UTC](https://discourse.julialang.org/t/zygote-differentiation-issues/54130 "2021-01-28T20:12:32Z")

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In an attempt to replicate what I saw here: " The impact of differentiable programming: how ∂P is enabling new science in Julia" function g(x) if x \< 0 print("Enter function name: ") getfield(Base, S…

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## [Custom row indexing in DataFrames](https://discourse.julialang.org/t/custom-row-indexing-in-dataframes/53959)

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**Author:** [@Impressium](https://discourse.julialang.org/u/Impressium)\
**Replies:** 2\
**Last updated:** [January 28, 2021, 6:04pm UTC](https://discourse.julialang.org/t/custom-row-indexing-in-dataframes/53959 "2021-01-28T18:04:17Z")

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Hey everybody :slight\_smile: Given a DataFrame df with columns I, A and C. Is there an way to set I as row index such that I can use df\[i,:\]or df\[i,a\] with i in I and a in A.

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## [Get conditional kernel densities in julia](https://discourse.julialang.org/t/get-conditional-kernel-densities-in-julia/54086)

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**Author:** [@claudio20497](https://discourse.julialang.org/u/claudio20497)\
**Replies:** 0\
**Last updated:** [January 27, 2021, 9:53pm UTC](https://discourse.julialang.org/t/get-conditional-kernel-densities-in-julia/54086 "2021-01-27T21:53:55Z")

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Hello, I was wondering if there is a method to get a conditional distribution out of a multivariate kde in julia, preferably using the package KernelDensityEstimate.jl. So say for example that I have the following code…

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## [Julia Plots savefig whitespace issue](https://discourse.julialang.org/t/julia-plots-savefig-whitespace-issue/54081)

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**Author:** [@gideonsimpson](https://discourse.julialang.org/u/gideonsimpson)\
**Replies:** 3\
**Last updated:** [January 28, 2021, 3:21am UTC](https://discourse.julialang.org/t/julia-plots-savefig-whitespace-issue/54081 "2021-01-28T03:21:57Z")

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When saving figures generated by Plots.jl with the pyplot, is there a straightforward way to trim the extra whitespace when I call savefig?

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## [Question regarding COSMO Convergence](https://discourse.julialang.org/t/question-regarding-cosmo-convergence/53996)

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**Author:** [@Y\_Li](https://discourse.julialang.org/u/Y_Li)\
**Replies:** 1\
**Last updated:** [January 28, 2021, 1:16am UTC](https://discourse.julialang.org/t/question-regarding-cosmo-convergence/53996 "2021-01-28T01:16:31Z")

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Hi, I have a question regarding COSMO package, this is my first time using it, what steps can I take when my code does not converge(but in reality it should)? It delivers message “Max\_iter\_reached” and stops at a value …

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## [Plot integrals](https://discourse.julialang.org/t/plot-integrals/54087)

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**Author:** [@brett\_knoss](https://discourse.julialang.org/u/brett_knoss)\
**Replies:** 6\
**Last updated:** [January 27, 2021, 11:27pm UTC](https://discourse.julialang.org/t/plot-integrals/54087 "2021-01-27T23:27:53Z")

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I can plot derivatives using ForwardDiff and Plots using ForwardDiff using Plots f(x)=x^2 df(x)=ForwardDiff.derivative(f(x), x) plot(df) but QuadGK.jl gives two answers so this method won’t work. Is there a way to pl…

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## [How to define JuMP expressions using a loop](https://discourse.julialang.org/t/how-to-define-jump-expressions-using-a-loop/54079)

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**Author:** [@Micah\_Mungal](https://discourse.julialang.org/u/Micah_Mungal)\
**Replies:** 1\
**Last updated:** [January 27, 2021, 10:03pm UTC](https://discourse.julialang.org/t/how-to-define-jump-expressions-using-a-loop/54079 "2021-01-27T22:03:48Z")

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Hi, I am trying to incorporate an expression into Julia using JuMP. Now I have been able to do this using MATLAB, but decided to switch to Julia for specific purposes. However based on the documentation provided for usin…

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## [Dispatch with @userplot and external recipes](https://discourse.julialang.org/t/dispatch-with-userplot-and-external-recipes/54045)

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**Author:** [@Libbum](https://discourse.julialang.org/u/Libbum)\
**Replies:** 1\
**Last updated:** [January 27, 2021, 7:54pm UTC](https://discourse.julialang.org/t/dispatch-with-userplot-and-external-recipes/54045 "2021-01-27T19:54:24Z")

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Hi all, I’m trying to learn the Plots.jl recipe syntax and have a few design questions. Say I have struct MyData{T} where {T\<:Union{One,Two}} ... end I’d like to define @userplot PlotCustom for this, and provide t…

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## [Auxiliary GLM Statistics](https://discourse.julialang.org/t/auxiliary-glm-statistics/14722)

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**Author:** [@iwelch](https://discourse.julialang.org/u/iwelch)\
**Replies:** 9\
**Last updated:** [January 27, 2021, 6:35pm UTC](https://discourse.julialang.org/t/auxiliary-glm-statistics/14722 "2021-01-27T18:35:30Z")

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Julia 1.0. GLM 1.0.0. My Basic Example julia\> using GLM, StatsBase julia\> y=\[1:10;\] ; X= hcat( fill(1,10), y.^2, y.^3 ); lm1= GLM.lm(X, y); Basic Questions is the sigma (i.e., sqrt(deviance(lm)/dof\_residual(lm)) al…

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## [Positve semidefinite constraint on SDP program in JuMP](https://discourse.julialang.org/t/positve-semidefinite-constraint-on-sdp-program-in-jump/53972)

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**Author:** [@cheng\_chen](https://discourse.julialang.org/u/cheng_chen)\
**Replies:** 11\
**Last updated:** [January 27, 2021, 2:51pm UTC](https://discourse.julialang.org/t/positve-semidefinite-constraint-on-sdp-program-in-jump/53972 "2021-01-27T14:51:56Z")

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I have to solve an SDP program. For example: min tr(Σ \* A ) s.t. Σ\[1:2,1:2\] \>= AΣA’ Σ \>= 0 Here is what I have: n = 4 d = 2 A = rand(d,n) B = rand(n,n) model = Model(ProxSDP.Optimizer) @variable(model, Σ\[1:n, 1:n\], …

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## [Generate a zero mean gaussian vector](https://discourse.julialang.org/t/generate-a-zero-mean-gaussian-vector/54056)

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**Author:** [@cheng\_chen](https://discourse.julialang.org/u/cheng_chen)\
**Replies:** 1\
**Last updated:** [January 27, 2021, 2:12pm UTC](https://discourse.julialang.org/t/generate-a-zero-mean-gaussian-vector/54056 "2021-01-27T14:12:37Z")

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How can I generate a zero mean 2 by 1 Gaussian vector with covariance Identity matrix?

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## [Truncated Gaussian Process with AbstractGPs?](https://discourse.julialang.org/t/truncated-gaussian-process-with-abstractgps/53779)

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**Author:** [@michielver](https://discourse.julialang.org/u/michielver)\
**Replies:** 4\
**Last updated:** [January 27, 2021, 1:05pm UTC](https://discourse.julialang.org/t/truncated-gaussian-process-with-abstractgps/53779 "2021-01-27T13:05:12Z")

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Hi all, So I have started to work with gaussian process for a time-series model in my case, and I have a variable of interest “score”, which is always between 0 and 4, and varies over time. Now I am using AbstractGPs a…

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