# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1795

[Latest](https://discourse.julialang.org/latest.md) · [Categories](https://discourse.julialang.org/categories.md) · [Tags](https://discourse.julialang.org/tags.md)

**Page:** 1796

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## [JuMP Multiple Models Design Question](https://discourse.julialang.org/t/jump-multiple-models-design-question/36230)

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**Author:** [@torgo](https://discourse.julialang.org/u/torgo)\
**Replies:** 5\
**Last updated:** [March 22, 2020, 12:26am UTC](https://discourse.julialang.org/t/jump-multiple-models-design-question/36230 "2020-03-22T00:26:35Z")

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What is the rationale behind throwing an error in this? using JuMP m1 = Model() @variable(m1, x \>= 0) m2 = Model() @variable(m2, x \>= 0) @objective(m1, Min, x) # this will error w/ variable not owned gives ERROR: L…

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## [HELP! Can not install packages... Git can not clone https://github.com/JuliaRegistries/General.git](https://discourse.julialang.org/t/help-can-not-install-packages-git-can-not-clone-https-github-com-juliaregistries-general-git/36241)

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**Author:** [@benibilme](https://discourse.julialang.org/u/benibilme)\
**Replies:** 2\
**Last updated:** [March 22, 2020, 12:26am UTC](https://discourse.julialang.org/t/help-can-not-install-packages-git-can-not-clone-https-github-com-juliaregistries-general-git/36241 "2020-03-22T00:26:17Z")

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Hello, I have a manjaro installed pc. I installed julia through manjaro package management system (pacman). The installed julia version is 1.3.1. I tried to install several packages from RELP but I receive following err…

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## [Find all indexes of string in string array](https://discourse.julialang.org/t/find-all-indexes-of-string-in-string-array/36302)

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**Author:** [@jonjilla](https://discourse.julialang.org/u/jonjilla)\
**Replies:** 12\
**Last updated:** [March 21, 2020, 11:05pm UTC](https://discourse.julialang.org/t/find-all-indexes-of-string-in-string-array/36302 "2020-03-21T23:05:01Z")

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Hello, Can someone help me with this? It seems like it should be easy but I can’t quite figure it out. I’m trying to find all of the array indicies in this String array that matches the search string Something like t…

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## [Broadcast highlighting on bitwise operators](https://discourse.julialang.org/t/broadcast-highlighting-on-bitwise-operators/36322)

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**Author:** [@martincornejo](https://discourse.julialang.org/u/martincornejo)\
**Replies:** 0\
**Last updated:** [March 21, 2020, 11:02pm UTC](https://discourse.julialang.org/t/broadcast-highlighting-on-bitwise-operators/36322 "2020-03-21T23:02:36Z")

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I’m not really sure where to report this, so I might very well do it here. I noticed the point on the broadcasting of bit-wise operators is not highlighted on Juno: .& .| .~

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## [Plots How to get exact point of intersection of a plot with axis?](https://discourse.julialang.org/t/plots-how-to-get-exact-point-of-intersection-of-a-plot-with-axis/36304)

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**Author:** [@programista](https://discourse.julialang.org/u/programista)\
**Replies:** 4\
**Last updated:** [March 21, 2020, 10:15pm UTC](https://discourse.julialang.org/t/plots-how-to-get-exact-point-of-intersection-of-a-plot-with-axis/36304 "2020-03-21T22:15:04Z")

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Plots How to get exact point of intersection of a plot with axis ? x=range(0,stop=2pi,length=365) plot!(sin.(x)) x is intersecting with y at -1 , I expect on 0 level Paul

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## [Weave -- is there a way to set the margins for a pdf?](https://discourse.julialang.org/t/weave-is-there-a-way-to-set-the-margins-for-a-pdf/35345)

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**Author:** [@brett\_knoss](https://discourse.julialang.org/u/brett_knoss)\
**Replies:** 2\
**Last updated:** [March 21, 2020, 9:37pm UTC](https://discourse.julialang.org/t/weave-is-there-a-way-to-set-the-margins-for-a-pdf/35345 "2020-03-21T21:37:54Z")

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I’m able to output my data to PDF using Weave, but some of my tables are cut off and put on a row below, ruinning flow. This is understandable, but the right margin is a good 2.5" to 3" from the end of the page, where t…

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## [\[ANN\] Dashboards 0.2.8](https://discourse.julialang.org/t/ann-dashboards-0-2-8/36318)

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**Author:** [@waralex](https://discourse.julialang.org/u/waralex)\
**Replies:** 0\
**Last updated:** [March 21, 2020, 9:17pm UTC](https://discourse.julialang.org/t/ann-dashboards-0-2-8/36318 "2020-03-21T21:17:41Z")

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Dashboards.lj version 0.2.8 released. dash-bootstrap-components added with prefix dbc. Examples of use will be soon pass\_changed\_props argument added to callback! function. For details see docs of callback! Bug fixe…

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## [Construct Julia Dataframe from row data](https://discourse.julialang.org/t/construct-julia-dataframe-from-row-data/36219)

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**Author:** [@nnn](https://discourse.julialang.org/u/nnn)\
**Replies:** 11\
**Last updated:** [March 21, 2020, 8:34pm UTC](https://discourse.julialang.org/t/construct-julia-dataframe-from-row-data/36219 "2020-03-21T20:34:05Z")

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When I have data in columns, I can construct a DataFrame like this: using Dataframes nameData = \["Alice", "Bob"\] surnameData = \["Smith", "Jones"\] df = DataFrame(name = nameData, surname = surnameData) However I have da…

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## [JupyterLab Variable Inspector](https://discourse.julialang.org/t/jupyterlab-variable-inspector/36242)

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**Author:** [@junder873](https://discourse.julialang.org/u/junder873)\
**Replies:** 1\
**Last updated:** [March 21, 2020, 7:58pm UTC](https://discourse.julialang.org/t/jupyterlab-variable-inspector/36242 "2020-03-21T19:58:29Z")

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Personally I use JupyterLab the most for my work. The one thing I don’t like about it is the lack of a variable pane. There is an extension for JupyterLab that provides this for Python and R, Variable Inspector. Most of …

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## [Help in making the code faster and/or reducing allocations?](https://discourse.julialang.org/t/help-in-making-the-code-faster-and-or-reducing-allocations/36299)

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**Author:** [@bashonubuntu](https://discourse.julialang.org/u/bashonubuntu)\
**Replies:** 2\
**Last updated:** [March 21, 2020, 7:22pm UTC](https://discourse.julialang.org/t/help-in-making-the-code-faster-and-or-reducing-allocations/36299 "2020-03-21T19:22:08Z")

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Thank you for the replies! I have realized this won’t be productive due to the length of the code so I’m closing this. I believe I can’t delete the thread myself but have flagged it so that it can be deleted sometime in …

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## [Polynomials & Polyfit](https://discourse.julialang.org/t/polynomials-polyfit/36309)

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**Author:** [@BLI](https://discourse.julialang.org/u/BLI)\
**Replies:** 0\
**Last updated:** [March 21, 2020, 6:26pm UTC](https://discourse.julialang.org/t/polynomials-polyfit/36309 "2020-03-21T18:26:58Z")

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I’m looking at basic use of Polynomials.jl with polyfit, polyval, etc., and have 3 questions: According to the Polynomials.jl documentation, there is a fourth argument for polyfit: sym, which I can use to specify a sym…

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## [Function argument Array{Array{ComplexF64,2},1} seems to be ignored](https://discourse.julialang.org/t/function-argument-array-array-complexf64-2-1-seems-to-be-ignored/36269)

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**Author:** [@kw\_martin](https://discourse.julialang.org/u/kw_martin)\
**Replies:** 19\
**Last updated:** [March 21, 2020, 5:20pm UTC](https://discourse.julialang.org/t/function-argument-array-array-complexf64-2-1-seems-to-be-ignored/36269 "2020-03-21T17:20:41Z")

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I have a function definition: function simBiquad(xin::Array{ComplexF64,1}, A::Array{Array{Complex{Float64},2},1}, B::Array{Array{Complex{Float64},2},1}, C::Array{Array{Complex{Flo…

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## [Saving Audio with Correct Sample Rate](https://discourse.julialang.org/t/saving-audio-with-correct-sample-rate/36298)

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**Author:** [@ambiso](https://discourse.julialang.org/u/ambiso)\
**Replies:** 4\
**Last updated:** [March 21, 2020, 3:53pm UTC](https://discourse.julialang.org/t/saving-audio-with-correct-sample-rate/36298 "2020-03-21T15:53:36Z")

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Hay! I’m trying to generate and save a very simple 440Hz waveform. Unfortunately, the generated file does not inherit the 44100Hz sample rate that I assigned. Instead it has a 8000Hz sample rate: $ file test.wav test…

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## [How to plot very large numbers of points and save the figures with small latencies for raw audio images?](https://discourse.julialang.org/t/how-to-plot-very-large-numbers-of-points-and-save-the-figures-with-small-latencies-for-raw-audio-images/30597)

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**Author:** [@mantzaris](https://discourse.julialang.org/u/mantzaris)\
**Replies:** 17\
**Last updated:** [March 21, 2020, 3:46pm UTC](https://discourse.julialang.org/t/how-to-plot-very-large-numbers-of-points-and-save-the-figures-with-small-latencies-for-raw-audio-images/30597 "2020-03-21T15:46:52Z")

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I want to plot the raw signal data from audio data that is sampled at the standard 44Kbps but there is a challenge if the signal is taken for a very long time; eg. 3 hrs of signal. There is then considerable latency in t…

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## [Multiplication times for complex matrices: julia vs Matlab](https://discourse.julialang.org/t/multiplication-times-for-complex-matrices-julia-vs-matlab/36163)

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**Author:** [@kw\_martin](https://discourse.julialang.org/u/kw_martin)\
**Replies:** 18\
**Last updated:** [March 21, 2020, 2:22pm UTC](https://discourse.julialang.org/t/multiplication-times-for-complex-matrices-julia-vs-matlab/36163 "2020-03-21T14:22:25Z")

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I’ve been looking at some different filter approaches for analyzing ECG signals using Matlab and have recently implemented them in julia in order to get a speed improvement. I have not been seeing the expected improvemen…

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## [Convex.jl: slow in creating constraints?](https://discourse.julialang.org/t/convex-jl-slow-in-creating-constraints/34775)

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**Author:** [@riccardomurri](https://discourse.julialang.org/u/riccardomurri)\
**Replies:** 34\
**Last updated:** [March 21, 2020, 11:57am UTC](https://discourse.julialang.org/t/convex-jl-slow-in-creating-constraints/34775 "2020-03-21T11:57:25Z")

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Hello, I have code that builds constraints for Convex.jl in a loop; each iteration of the loop takes ~5 minutes (on fairly recent hardware). Is this expected or am I doing something wrong? # solution vector X = Variab…

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## [Hdf5plot\_write error](https://discourse.julialang.org/t/hdf5plot-write-error/35036)

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**Author:** [@hendri54](https://discourse.julialang.org/u/hendri54)\
**Replies:** 4\
**Last updated:** [March 21, 2020, 11:54am UTC](https://discourse.julialang.org/t/hdf5plot-write-error/35036 "2020-03-21T11:54:45Z")

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Trying to write a plot in hdf5 format yields the following error: using Plots, HDF5 julia\> hdf5() Plots.HDF5Backend() julia\> p=plot(1:10, 1:10); julia\> Plots.hdf5plot\_write(p, "plotsave.hdf5") ERROR: MethodError: no …

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## [Findfirst ERROR: MethodError: no method matching keys](https://discourse.julialang.org/t/findfirst-error-methoderror-no-method-matching-keys/36292)

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**Author:** [@yakir12](https://discourse.julialang.org/u/yakir12)\
**Replies:** 1\
**Last updated:** [March 21, 2020, 8:17am UTC](https://discourse.julialang.org/t/findfirst-error-methoderror-no-method-matching-keys/36292 "2020-03-21T08:17:57Z")

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I’m sure this is addressed somewhere, I just can’t (drum-roll) find it. Given some matrix, I want to find the first row whose sum is odd: julia\> m = \[0 0 0; 1 1 1; 2 2 2\] 3×3 Array{Int64,2}: 0 0 0 1 1 1 2 2 2 …

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## [Running Julia script with predefined environment](https://discourse.julialang.org/t/running-julia-script-with-predefined-environment/35997)

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**Author:** [@arvindmohan](https://discourse.julialang.org/u/arvindmohan)\
**Replies:** 3\
**Last updated:** [March 21, 2020, 6:43am UTC](https://discourse.julialang.org/t/running-julia-script-with-predefined-environment/35997 "2020-03-21T06:43:00Z")

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Julia newbie here. I downloaded a package with Project.toml and instantiated the environment in Julia interactively so all deps were installed. Now I need to run a script (here, testing.jl) thru command line in this envi…

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## [DifferentialEquations Parameters](https://discourse.julialang.org/t/differentialequations-parameters/36289)

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**Author:** [@jacob-roth](https://discourse.julialang.org/u/jacob-roth)\
**Replies:** 3\
**Last updated:** [March 21, 2020, 5:13am UTC](https://discourse.julialang.org/t/differentialequations-parameters/36289 "2020-03-21T05:13:21Z")

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When passing parameters p to the function f of an ODEProblem (or any problem type in the DiffEq universe), does p always have to be an array? Is there a “best practices” reason for why I shouldn’t use Dicts to hold my pa…

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## [\[ANN\] Multigraphs.jl - A multigraph extension for LightGraphs.jl](https://discourse.julialang.org/t/ann-multigraphs-jl-a-multigraph-extension-for-lightgraphs-jl/35788)

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**Author:** [@Roger-luo](https://discourse.julialang.org/u/Roger-luo)\
**Replies:** 7\
**Last updated:** [March 21, 2020, 4:02am UTC](https://discourse.julialang.org/t/ann-multigraphs-jl-a-multigraph-extension-for-lightgraphs-jl/35788 "2020-03-21T04:02:32Z")

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I’m happy to announce this great work done by Chen Zhao. It implements multi-graph based on LightGraph. This is part of the infrastructure we built towards a zx-calculus based compiler for quantum circuits. But we als…

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## [Infinite matrices in Julia?](https://discourse.julialang.org/t/infinite-matrices-in-julia/36278)

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**Author:** [@VikoRifeo](https://discourse.julialang.org/u/VikoRifeo)\
**Replies:** 2\
**Last updated:** [March 20, 2020, 9:47pm UTC](https://discourse.julialang.org/t/infinite-matrices-in-julia/36278 "2020-03-20T21:47:25Z")

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I’m trying to subtype AbstractMatrix for a matrix which has infinite rows. What should axes, size and length return? Floating-point Inf is probably out, because the indices must be integers. I could report it as typemin(…

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## [Problem with cost function in JuMP](https://discourse.julialang.org/t/problem-with-cost-function-in-jump/36173)

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**Author:** [@mleprovost](https://discourse.julialang.org/u/mleprovost)\
**Replies:** 3\
**Last updated:** [March 20, 2020, 9:43pm UTC](https://discourse.julialang.org/t/problem-with-cost-function-in-jump/36173 "2020-03-20T21:43:20Z")

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Hello everyone, I am interested in the following optimization problem that I would like to solve with JuMP: \\begin{split} \\min\_{x \\in \\mathbb{R}^n} & (z^Tx)^2 - \\log(b^T x\[l:\\mbox{end}\])\\\\ \\mbox{ subject to }& x\[l:\\mbo…

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## [How do I lessen memory allocation and speedup block inverse?](https://discourse.julialang.org/t/how-do-i-lessen-memory-allocation-and-speedup-block-inverse/36273)

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**Author:** [@the\_daemon\_lord](https://discourse.julialang.org/u/the_daemon_lord)\
**Replies:** 2\
**Last updated:** [March 20, 2020, 9:38pm UTC](https://discourse.julialang.org/t/how-do-i-lessen-memory-allocation-and-speedup-block-inverse/36273 "2020-03-20T21:38:20Z")

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Hello! I was trying to implement block inverses in Julia and noticed that in some cases it’s faster than the builtin inv() but it also allocates way more memory. Is there any way to improve this function? This is my im…

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## [BoundsError using reduce function (Julia 1.3.1)](https://discourse.julialang.org/t/boundserror-using-reduce-function-julia-1-3-1/36232)

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**Author:** [@erratic](https://discourse.julialang.org/u/erratic)\
**Replies:** 7\
**Last updated:** [March 20, 2020, 8:25pm UTC](https://discourse.julialang.org/t/boundserror-using-reduce-function-julia-1-3-1/36232 "2020-03-20T20:25:50Z")

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I get the following error when I try to reduce the tuple array. Honestly I have no idea why this happen. julia\> a = \[(x, rand()\*10) for x in 1:20\] 20-element Array{Tuple{Int64,Float64},1}: (1, 8.090189006962254) (2,…

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## [CPLEX model answer \`has\_duals\` differently if variables were integer](https://discourse.julialang.org/t/cplex-model-answer-has-duals-differently-if-variables-were-integer/36276)

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**Author:** [@Henrique\_Becker](https://discourse.julialang.org/u/Henrique_Becker)\
**Replies:** 1\
**Last updated:** [March 20, 2020, 7:10pm UTC](https://discourse.julialang.org/t/cplex-model-answer-has-duals-differently-if-variables-were-integer/36276 "2020-03-20T19:10:47Z")

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Hey it is me again, XD, I would want to know if this behavior is expected (i.e., if this behavior is expected to be solver-dependent): import CPLEX, Gurobi, GLPK using JuMP function test\_duals(solver\_sym, relaxed\_mip)…

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## [Julia can process text similar to Perl](https://discourse.julialang.org/t/julia-can-process-text-similar-to-perl/36201)

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**Author:** [@Marks](https://discourse.julialang.org/u/Marks)\
**Replies:** 12\
**Last updated:** [March 20, 2020, 6:44pm UTC](https://discourse.julialang.org/t/julia-can-process-text-similar-to-perl/36201 "2020-03-20T18:44:43Z")

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Does Julia have the same word processing functions as Perl?

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## [Benchmarking Optimization Heuristics](https://discourse.julialang.org/t/benchmarking-optimization-heuristics/36265)

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**Author:** [@Phillip\_Sutton](https://discourse.julialang.org/u/Phillip_Sutton)\
**Replies:** 2\
**Last updated:** [March 20, 2020, 6:28pm UTC](https://discourse.julialang.org/t/benchmarking-optimization-heuristics/36265 "2020-03-20T18:28:06Z")

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Does anyone have benchmarks/success stories in running Heuristics in Julia vice other Languages (Python, R, etc.)? I’m on a new team (so I don’t want to make too many bold changes) and a firm believer in Julia, looking f…

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## [Name JuMP constraints in loop for use in writing .lp file](https://discourse.julialang.org/t/name-jump-constraints-in-loop-for-use-in-writing-lp-file/36220)

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**Author:** [@ccampaigne](https://discourse.julialang.org/u/ccampaigne)\
**Replies:** 2\
**Last updated:** [March 19, 2020, 9:45pm UTC](https://discourse.julialang.org/t/name-jump-constraints-in-loop-for-use-in-writing-lp-file/36220 "2020-03-19T21:45:47Z")

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Newb here (I’m a Python “user”). In JuMP 0.21.1, I want to create multiple named constraints either through vectorization or looping, and write LP files with those names so that I can easily search them for debugging pur…

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## [Facet enumeration](https://discourse.julialang.org/t/facet-enumeration/36270)

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**Author:** [@Tamas\_Papp](https://discourse.julialang.org/u/Tamas_Papp)\
**Replies:** 0\
**Last updated:** [March 20, 2020, 4:52pm UTC](https://discourse.julialang.org/t/facet-enumeration/36270 "2020-03-20T16:52:09Z")

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I am looking for a package that implements facet enumeration, ie given the vertices of an \\mathbb{R}^n convex polytope (3 \\le n \\le 5), return the list of facets with a vertex index for each. The polytope can be assumed…

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