# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=454

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**Page:** 455

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## [Best way of checking whether a polyhedron contains an integral point](https://discourse.julialang.org/t/best-way-of-checking-whether-a-polyhedron-contains-an-integral-point/36766)

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**Author:** [@python15](https://discourse.julialang.org/u/python15)\
**Replies:** 8\
**Last updated:** [April 2, 2020, 6:57pm UTC](https://discourse.julialang.org/t/best-way-of-checking-whether-a-polyhedron-contains-an-integral-point/36766 "2020-04-02T18:57:41Z")

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Hey! I’m quite new to Julia and try to solve the following problem efficiently: For a given bounded polyhedron (by the linear equations Ax = 0 and bounds on x), I have to check whether it contains a non-negative integr…

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## [GPU Sort Function](https://discourse.julialang.org/t/gpu-sort-function/36065)

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**Author:** [@bmit](https://discourse.julialang.org/u/bmit)\
**Replies:** 20\
**Last updated:** [April 2, 2020, 1:28pm UTC](https://discourse.julialang.org/t/gpu-sort-function/36065 "2020-04-02T13:28:25Z")

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I was wondering if anyone has implemented a sort or partialsort function that is GPU friendly. Ultimately I need to compute statistical metrics of a dataset such as median or quartile that require sorting. I saw it was …

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## [Voronoi Visualization](https://discourse.julialang.org/t/voronoi-visualization/36602)

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**Author:** [@gideonsimpson](https://discourse.julialang.org/u/gideonsimpson)\
**Replies:** 16\
**Last updated:** [April 2, 2020, 7:42am UTC](https://discourse.julialang.org/t/voronoi-visualization/36602 "2020-04-02T07:42:47Z")

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I have a set of points in 2D that I’m using to define Voronoi cells using NearestNeighbors.jl. I’d like to do some visualization of this. The two things I would ideally like to be able to do: Plot the Voronoi cells C…

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## [Numerical differentiation for functions of complex numbers](https://discourse.julialang.org/t/numerical-differentiation-for-functions-of-complex-numbers/341)

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**Author:** [@ChrisRackauckas](https://discourse.julialang.org/u/ChrisRackauckas)\
**Replies:** 15\
**Last updated:** [April 2, 2020, 4:09am UTC](https://discourse.julialang.org/t/numerical-differentiation-for-functions-of-complex-numbers/341 "2020-04-02T04:09:55Z")

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Does anyone know of an available package which supports differentiating complex numbers? This has come up when trying to make stiff solvers for ODEs compatible with complex numbers since numerical Jacobians usually need …

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## [Parallel coordinates plot with PlotlyJS](https://discourse.julialang.org/t/parallel-coordinates-plot-with-plotlyjs/36672)

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**Author:** [@healyp](https://discourse.julialang.org/u/healyp)\
**Replies:** 4\
**Last updated:** [April 1, 2020, 9:15pm UTC](https://discourse.julialang.org/t/parallel-coordinates-plot-with-plotlyjs/36672 "2020-04-01T21:15:05Z")

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I would like to use PlotlyJS’s parallel coordinates plot to achieve something similar to this python example. I have tried extracting into separate dataframes my separate groupings, built separate traces and then, fina…

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## [Sampling from a normal distribution](https://discourse.julialang.org/t/sampling-from-a-normal-distribution/36848)

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**Author:** [@samantp](https://discourse.julialang.org/u/samantp)\
**Replies:** 4\
**Last updated:** [April 1, 2020, 4:28pm UTC](https://discourse.julialang.org/t/sampling-from-a-normal-distribution/36848 "2020-04-01T16:28:11Z")

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I am trying to draw 1000 random values from a normal distribution with a specific mean and standard deviation. Additionally, the values cannot be negative, which is an added constraint. To do this I have been trying to u…

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## [Optim.jl - How to find local maxima of multivariate function](https://discourse.julialang.org/t/optim-jl-how-to-find-local-maxima-of-multivariate-function/36853)

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**Author:** [@mthelm85](https://discourse.julialang.org/u/mthelm85)\
**Replies:** 3\
**Last updated:** [April 1, 2020, 4:21pm UTC](https://discourse.julialang.org/t/optim-jl-how-to-find-local-maxima-of-multivariate-function/36853 "2020-04-01T16:21:56Z")

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Pardon my ignorance (if you’ve seen any recent posts of mine you’ll know I’ve been studying calculus lately) but I’m trying to understand how to find local maxima of a multivariate function with Optim.jl. Given the follo…

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## [Partially empty 2d histogram Plots.jl](https://discourse.julialang.org/t/partially-empty-2d-histogram-plots-jl/36828)

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**Author:** [@isentropic](https://discourse.julialang.org/u/isentropic)\
**Replies:** 2\
**Last updated:** [April 1, 2020, 7:48am UTC](https://discourse.julialang.org/t/partially-empty-2d-histogram-plots-jl/36828 "2020-04-01T07:48:05Z")

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Attempting plotting a small circle in 2d histogram (with custom bins and limits), gives a natural result in pyplot: However, Plots for some reason gives blank pixels (same image):

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## [Zygote: meaning of @adjoint add(a, b) = add(a, b), Δ -\> (Δ, Δ)](https://discourse.julialang.org/t/zygote-meaning-of-adjoint-add-a-b-add-a-b/36707)

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**Author:** [@jaynick](https://discourse.julialang.org/u/jaynick)\
**Replies:** 4\
**Last updated:** [March 31, 2020, 11:18pm UTC](https://discourse.julialang.org/t/zygote-meaning-of-adjoint-add-a-b-add-a-b/36707 "2020-03-31T23:18:52Z")

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The zygote landing page has the example @adjoint add(a, b) = add(a, b), Δ -\> (Δ, Δ) Can someone explain what the Δ -\> (Δ, Δ) means? I would have expected the derivatives to be 1,1.

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## [Number of constraints](https://discourse.julialang.org/t/number-of-constraints/36798)

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**Author:** [@angeloaliano1](https://discourse.julialang.org/u/angeloaliano1)\
**Replies:** 1\
**Last updated:** [March 31, 2020, 7:59pm UTC](https://discourse.julialang.org/t/number-of-constraints/36798 "2020-03-31T19:59:57Z")

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Dear all, The command num\_constraints() can determine the number of equality constraints in a given model? How can I find this?

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## [CuArrays v2.0.1 results in segmentation fault for LinearAlgebra.mul!](https://discourse.julialang.org/t/cuarrays-v2-0-1-results-in-segmentation-fault-for-linearalgebra-mul/36755)

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**Author:** [@fedoroff](https://discourse.julialang.org/u/fedoroff)\
**Replies:** 4\
**Last updated:** [March 31, 2020, 7:56am UTC](https://discourse.julialang.org/t/cuarrays-v2-0-1-results-in-segmentation-fault-for-linearalgebra-mul/36755 "2020-03-31T07:56:51Z")

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The following code with CuArrays v2.0.1 results in segmentation fault on my computer: import CuArrays import LinearAlgebra N = 1024 y = CuArrays.zeros(N) x = CuArrays.zeros(N) A = CuArrays.zeros((N, N)) LinearAlgebra…

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## [Alternative to deprecated NetworkViz?](https://discourse.julialang.org/t/alternative-to-deprecated-networkviz/36713)

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**Author:** [@Xarg](https://discourse.julialang.org/u/Xarg)\
**Replies:** 1\
**Last updated:** [March 31, 2020, 3:21am UTC](https://discourse.julialang.org/t/alternative-to-deprecated-networkviz/36713 "2020-03-31T03:21:12Z")

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Hi, I’m looking to convert one of my R notebooks to Julia, and one of the packages I’m using is VisNetwork which gives me an interactive graph I can click on nodes to get additional information on, and drag them around. …

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## [Trouble making a pivot table](https://discourse.julialang.org/t/trouble-making-a-pivot-table/36610)

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**Author:** [@brett\_knoss](https://discourse.julialang.org/u/brett_knoss)\
**Replies:** 19\
**Last updated:** [March 30, 2020, 1:21pm UTC](https://discourse.julialang.org/t/trouble-making-a-pivot-table/36610 "2020-03-30T13:21:00Z")

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df1 = DataFrame(XLSX.readtable("C:/Users/Brett/Documents/Soc332Assignment3.xlsx","TestData")...) #change everything to Float64 for name in names(df1) df1\[!, name\] = identity.(df1\[:, name\]) end #change everythin…

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## [GraphPlot.jl: possible to change font family?](https://discourse.julialang.org/t/graphplot-jl-possible-to-change-font-family/36699)

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**Author:** [@Igor\_Douven](https://discourse.julialang.org/u/Igor_Douven)\
**Replies:** 3\
**Last updated:** [March 30, 2020, 1:04pm UTC](https://discourse.julialang.org/t/graphplot-jl-possible-to-change-font-family/36699 "2020-03-30T13:04:28Z")

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I’m using gplot() from the GraphPlot.jl package to plot a graph created with LightGraphs.jl. I’d like to change the font family used for the node labels, but can’t find in the documentation how to do that. Does anyone kn…

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## [Multiple variable assignment and ODE solution extracting](https://discourse.julialang.org/t/multiple-variable-assignment-and-ode-solution-extracting/36647)

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**Author:** [@jmaffi](https://discourse.julialang.org/u/jmaffi)\
**Replies:** 4\
**Last updated:** [March 30, 2020, 12:11pm UTC](https://discourse.julialang.org/t/multiple-variable-assignment-and-ode-solution-extracting/36647 "2020-03-30T12:11:33Z")

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Hi there! I am quite new to Julia and have read manuals, tutorials, FAQs, and almost all question threads regarding the following, but have not yet found a solution. I have a system of 17 ordinary differential equation…

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## [Modifying legend markersize/linelength of a Plots/PyPlot plot after creation](https://discourse.julialang.org/t/modifying-legend-markersize-linelength-of-a-plots-pyplot-plot-after-creation/36723)

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**Author:** [@dapz](https://discourse.julialang.org/u/dapz)\
**Replies:** 0\
**Last updated:** [March 30, 2020, 9:03am UTC](https://discourse.julialang.org/t/modifying-legend-markersize-linelength-of-a-plots-pyplot-plot-after-creation/36723 "2020-03-30T09:03:25Z")

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Hi, I’m using a lot Plots.jl as I like having the common interface, but right now using mostly the PyPlot backend. I don’t want to use directly PyPlot as I coded some Plots recipes that I use. I have trouble with the le…

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## [Procedural Nonlinear Constaint Generation - String to NLconstraint](https://discourse.julialang.org/t/procedural-nonlinear-constaint-generation-string-to-nlconstraint/34799)

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**Author:** [@r-b0](https://discourse.julialang.org/u/r-b0)\
**Replies:** 9\
**Last updated:** [March 30, 2020, 1:53am UTC](https://discourse.julialang.org/t/procedural-nonlinear-constaint-generation-string-to-nlconstraint/34799 "2020-03-30T01:53:29Z")

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I am implementing a large scale nonlinear program solver using the JuMP interface to IPOPT. The Nonlinear Modeling section of JuMP v0.21.0 documentation clearly explicates that all expressions used in NLconstraint and N…

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## [Zygote docs suggest flux is out of date?](https://discourse.julialang.org/t/zygote-docs-suggest-flux-is-out-of-date/36706)

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**Author:** [@jaynick](https://discourse.julialang.org/u/jaynick)\
**Replies:** 0\
**Last updated:** [March 29, 2020, 11:14pm UTC](https://discourse.julialang.org/t/zygote-docs-suggest-flux-is-out-of-date/36706 "2020-03-29T23:14:26Z")

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In the zygote docs it says However, implicit parameters exist mainly for compatibility with Flux’s current AD; it’s recommended to use the other approaches unless you need this, where implicit parameters refer to the s…

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## [DataFrame by new columns containing arrays](https://discourse.julialang.org/t/dataframe-by-new-columns-containing-arrays/36614)

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**Author:** [@yakir12](https://discourse.julialang.org/u/yakir12)\
**Replies:** 13\
**Last updated:** [March 29, 2020, 1:59pm UTC](https://discourse.julialang.org/t/dataframe-by-new-columns-containing-arrays/36614 "2020-03-29T13:59:45Z")

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In DataFrames we can do this: by(iris, :Species, \[:PetalLength, :SepalLength\] =\> x -\> (a=mean(x.PetalLength)/mean(x.SepalLength), b=sum(x.PetalLength))) 3×3 DataFrame │ Row │ Species │ a │ b …

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## [(not julia) Help make PPE for Hospitals (3-D printer required)](https://discourse.julialang.org/t/not-julia-help-make-ppe-for-hospitals-3-d-printer-required/36648)

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**Author:** [@anon92994695](https://discourse.julialang.org/u/anon92994695)\
**Replies:** 1\
**Last updated:** [March 29, 2020, 1:55am UTC](https://discourse.julialang.org/t/not-julia-help-make-ppe-for-hospitals-3-d-printer-required/36648 "2020-03-29T01:55:27Z")

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Many hospitals especially in the USA are in dire need of PPE and may not get it on time given the pandemic. For instance University of Michigan Hospital is accepting 3-D printed face shields (Ann Arbor residents join eff…

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## [Extended Slack PPL discussion](https://discourse.julialang.org/t/extended-slack-ppl-discussion/36623)

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**Author:** [@cscherrer](https://discourse.julialang.org/u/cscherrer)\
**Replies:** 5\
**Last updated:** [March 28, 2020, 5:25pm UTC](https://discourse.julialang.org/t/extended-slack-ppl-discussion/36623 "2020-03-28T17:25:51Z")

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Hi, there was a nice thread today on the Julia Slack PPL channel. Because it’s the free version, this will scroll into oblivion, so I thought I’d capture it for reference and in case it’s useful to anyone else: I had …

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## [Solving an optimal control problem with Optim.jl](https://discourse.julialang.org/t/solving-an-optimal-control-problem-with-optim-jl/36635)

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**Author:** [@roi.holtzman](https://discourse.julialang.org/u/roi.holtzman)\
**Replies:** 4\
**Last updated:** [March 28, 2020, 2:17pm UTC](https://discourse.julialang.org/t/solving-an-optimal-control-problem-with-optim-jl/36635 "2020-03-28T14:17:57Z")

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I am trying to solve an optimal control problem in Julia. I tried using NLOptControl.jl and JuMP.jl but ran into some difficulties. See this post. Therefore I am trying to use Optim.jl as an optimizer. Since my optimiza…

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## [Is there a way to speed up this implementation of BLSTM layer?](https://discourse.julialang.org/t/is-there-a-way-to-speed-up-this-implementation-of-blstm-layer/36429)

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**Author:** [@Azamat](https://discourse.julialang.org/u/Azamat)\
**Replies:** 1\
**Last updated:** [March 28, 2020, 11:00am UTC](https://discourse.julialang.org/t/is-there-a-way-to-speed-up-this-implementation-of-blstm-layer/36429 "2020-03-28T11:00:46Z")

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I have implemented the BLSTM layer for a batch of sequences input stored as a 3D array with dimensions ordered as \[features × time × batch\]. And I wonder if there is a faster way to implement it. I’m interested in the sp…

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## [Bug when using DSDP versus SCS optimiser with JuMP](https://discourse.julialang.org/t/bug-when-using-dsdp-versus-scs-optimiser-with-jump/36554)

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**Author:** [@tdp](https://discourse.julialang.org/u/tdp)\
**Replies:** 2\
**Last updated:** [March 28, 2020, 8:30am UTC](https://discourse.julialang.org/t/bug-when-using-dsdp-versus-scs-optimiser-with-jump/36554 "2020-03-28T08:30:04Z")

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Hi, How do I resolve the error below generated when I run my code using the DSDP optimiser? I get the right answer, without errors, when I run my code using the SCS optimiser instead. (This question is a follow-up to t…

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## [Where can I get detailed longitudinal data of the COVID-19 pandemics?](https://discourse.julialang.org/t/where-can-i-get-detailed-longitudinal-data-of-the-covid-19-pandemics/36577)

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**Author:** [@Juan](https://discourse.julialang.org/u/Juan)\
**Replies:** 4\
**Last updated:** [March 27, 2020, 4:56pm UTC](https://discourse.julialang.org/t/where-can-i-get-detailed-longitudinal-data-of-the-covid-19-pandemics/36577 "2020-03-27T16:56:32Z")

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Where can I download a full dataset of the SARS-CoV-2 pandemics containing time information for each individual (date of infection, date of death, age, gender, weight, censoring information…) It’s important to get this …

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## [Installing Ipopt](https://discourse.julialang.org/t/installing-ipopt/35608)

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**Author:** [@varun\_yaramasu](https://discourse.julialang.org/u/varun_yaramasu)\
**Replies:** 8\
**Last updated:** [March 27, 2020, 4:46pm UTC](https://discourse.julialang.org/t/installing-ipopt/35608 "2020-03-27T16:46:58Z")

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julia\> Pkg.build("Ipopt") Building CodecZlib ─→ \`C:\\Users\\yaramasv\\.juliapro\\JuliaPro\_v1.3.1-1\\packages\\CodecZlib\\5t9zO\\deps\\build.log\` Building MbedTLS ───→ \`C:\\Users\\yaramasv\\.juliapro\\JuliaPro\_v1.3.1-1\\packages\\…

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## [Point Julia to Cbc built from source](https://discourse.julialang.org/t/point-julia-to-cbc-built-from-source/36516)

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**Author:** [@joshuastowell25](https://discourse.julialang.org/u/joshuastowell25)\
**Replies:** 5\
**Last updated:** [March 27, 2020, 3:30pm UTC](https://discourse.julialang.org/t/point-julia-to-cbc-built-from-source/36516 "2020-03-27T15:30:57Z")

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Hello All, I am trying to get JuMP and Cbc to use multithreading. Turns out that in order to do this you have to build Cbc from source with the --enable-cbc-parallel option. I have followed the cbc build instructions i…

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## [Convert model with anonymous variables to "readable" form](https://discourse.julialang.org/t/convert-model-with-anonymous-variables-to-readable-form/36594)

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**Author:** [@richard046](https://discourse.julialang.org/u/richard046)\
**Replies:** 5\
**Last updated:** [March 27, 2020, 2:29pm UTC](https://discourse.julialang.org/t/convert-model-with-anonymous-variables-to-readable-form/36594 "2020-03-27T14:29:34Z")

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Hello, I have a code(written by others) that builds a JuMP model, but I can’t see what are the constraints, becouse it has \_\_anon\_\_ variables, like this: Min \_\_anon\_\_ + \_\_anon\_\_ Subject to \_\_anon\_\_ - \_\_anon\_\_ == 0.5 …

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## [Spearman Correlation, How do I find rho?](https://discourse.julialang.org/t/spearman-correlation-how-do-i-find-rho/36291)

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**Author:** [@brett\_knoss](https://discourse.julialang.org/u/brett_knoss)\
**Replies:** 17\
**Last updated:** [March 27, 2020, 8:26am UTC](https://discourse.julialang.org/t/spearman-correlation-how-do-i-find-rho/36291 "2020-03-27T08:26:57Z")

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B= df.Crude\_Birth\_Rate Employment\_df = DataFrame(A=df.Female\_Employment,B=df.Crude\_Birth\_Rate, )corspearman(x=A, y=B) = cor(tiedrank(A), tiedrank(B)) I’m trying to do a Spearman Correlation Test, because I know from my…

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## [Using a Voronoi tessellation to represent a density field](https://discourse.julialang.org/t/using-a-voronoi-tessellation-to-represent-a-density-field/36585)

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**Author:** [@arnauqb](https://discourse.julialang.org/u/arnauqb)\
**Replies:** 0\
**Last updated:** [March 27, 2020, 7:13am UTC](https://discourse.julialang.org/t/using-a-voronoi-tessellation-to-represent-a-density-field/36585 "2020-03-27T07:13:16Z")

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Hi all, I have a set of 2D points (x,y) with a density value associated to them. I want to create a 2D density field from that, using a Voronoi tessellation. I am then interested to be able to query the density value fo…

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