# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?page=513

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**Page:** 514

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## [Type safe and expressive "tensor" code](https://discourse.julialang.org/t/type-safe-and-expressive-tensor-code/19338)

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**Author:** [@datnamer](https://discourse.julialang.org/u/datnamer)\
**Replies:** 3\
**Last updated:** [January 11, 2019, 1:27am UTC](https://discourse.julialang.org/t/type-safe-and-expressive-tensor-code/19338 "2019-01-11T01:27:19Z")

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There’s been some buzz lately about more expressive, and type safe array code for deep learning. One specific initiative has been the use of arrays with named dimensions: GitHub - ctongfei/nexus: Experimental tensor-ty…

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## [Query.jl - how to select identical rows differing by one column](https://discourse.julialang.org/t/query-jl-how-to-select-identical-rows-differing-by-one-column/19367)

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**Author:** [@elshera](https://discourse.julialang.org/u/elshera)\
**Replies:** 11\
**Last updated:** [January 10, 2019, 6:36am UTC](https://discourse.julialang.org/t/query-jl-how-to-select-identical-rows-differing-by-one-column/19367 "2019-01-10T06:36:33Z")

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Hi, I have a dataframe of columns A,B,C, O. How can I write a query which shows me those rows which have same pattern in the columns A,B,C but different value for column O ? example: A, B, C, O 2, 3, 4, 10 2 ,3, 4,…

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## [NSException for Pyplot](https://discourse.julialang.org/t/nsexception-for-pyplot/19391)

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**Author:** [@ohsonice](https://discourse.julialang.org/u/ohsonice)\
**Replies:** 1\
**Last updated:** [January 9, 2019, 4:36pm UTC](https://discourse.julialang.org/t/nsexception-for-pyplot/19391 "2019-01-09T16:36:04Z")

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I am getting the following exception when attempting to plot using pyplot: julia\> using Plots julia\> pyplot() Plots.PyPlotBackend() julia\> plot(rand(100)) 2019-01-08 10:43:51.574 julia\[90768:45265541\] -\[NSApplication …

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## [Write a REST interface like Flask](https://discourse.julialang.org/t/write-a-rest-interface-like-flask/18538)

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**Author:** [@Seanny123](https://discourse.julialang.org/u/Seanny123)\
**Replies:** 22\
**Last updated:** [January 9, 2019, 3:17pm UTC](https://discourse.julialang.org/t/write-a-rest-interface-like-flask/18538 "2019-01-09T15:17:22Z")

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There are a few posts about write a REST interface using Julia wherein a number of libraries are recommended. However, I’m unclear if any of them resemble Flask? What I appreciate about Flask is how easy it is to define…

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## [Charts from sysstat data](https://discourse.julialang.org/t/charts-from-sysstat-data/19411)

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**Author:** [@johnh](https://discourse.julialang.org/u/johnh)\
**Replies:** 1\
**Last updated:** [January 9, 2019, 4:04am UTC](https://discourse.julialang.org/t/charts-from-sysstat-data/19411 "2019-01-09T04:04:28Z")

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What is a good utility to produce pie charts from CSV files? My first thoughts would be the Queryverse - or shoud I be looking at something else? Specifically I would like to produce pie charts for the sums of differen…

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## [Help with Logit NLP problem](https://discourse.julialang.org/t/help-with-logit-nlp-problem/19296)

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**Author:** [@SonLe](https://discourse.julialang.org/u/SonLe)\
**Replies:** 1\
**Last updated:** [January 8, 2019, 4:06pm UTC](https://discourse.julialang.org/t/help-with-logit-nlp-problem/19296 "2019-01-08T16:06:56Z")

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Hi. I found this thesis online and wanted to reproduce the section Robust both Feature and Label for Logistic Regression. The Logit model here looks like this: My problem is that when i compute the first constraint …

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## [Problem With Integer Stack Size](https://discourse.julialang.org/t/problem-with-integer-stack-size/19384)

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**Author:** [@muriloasouza](https://discourse.julialang.org/u/muriloasouza)\
**Replies:** 1\
**Last updated:** [January 8, 2019, 4:03pm UTC](https://discourse.julialang.org/t/problem-with-integer-stack-size/19384 "2019-01-08T16:03:41Z")

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Hello, using Couenne to solve a MINLP, but i’m getting this error: Problem with integer stack size 1 1 6 Warning: Not solved to optimality, status: Error If you need any more info, let me …

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## [Integro-differential equations with DifferentialEquations.jl](https://discourse.julialang.org/t/integro-differential-equations-with-differentialequations-jl/19265)

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**Author:** [@lappet](https://discourse.julialang.org/u/lappet)\
**Replies:** 4\
**Last updated:** [January 8, 2019, 7:52am UTC](https://discourse.julialang.org/t/integro-differential-equations-with-differentialequations-jl/19265 "2019-01-08T07:52:01Z")

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The integro-differential equations I need to solve are of this form: http://mathb.in/30204. While I already have written a solver for a simple test problem (s. code below), the type of equation shown in the link above ca…

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## [Error in FFT?](https://discourse.julialang.org/t/error-in-fft/19310)

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**Author:** [@LewisHein](https://discourse.julialang.org/u/LewisHein)\
**Replies:** 5\
**Last updated:** [January 7, 2019, 2:25pm UTC](https://discourse.julialang.org/t/error-in-fft/19310 "2019-01-07T14:25:04Z")

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Brief problem here, I will try to add graphs later. I can create a function that returns a gaussian, discretize it, and take the FFT with fft() or rfft() from the FFTW module. This does not return a gaussian as it should…

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## [How to calculate a weighted mean with missing observations](https://discourse.julialang.org/t/how-to-calculate-a-weighted-mean-with-missing-observations/19281)

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**Author:** [@pdeffebach](https://discourse.julialang.org/u/pdeffebach)\
**Replies:** 17\
**Last updated:** [January 5, 2019, 6:18pm UTC](https://discourse.julialang.org/t/how-to-calculate-a-weighted-mean-with-missing-observations/19281 "2019-01-05T18:18:12Z")

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In my work not in Julia I often want to find weighted means when i have lots of missing data: both the vector of values contains missing values and the weights have missing values. using StatsBase, DataFrames df = DataF…

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## [Random Error: Unsupported feature Hess](https://discourse.julialang.org/t/random-error-unsupported-feature-hess/19306)

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**Author:** [@neseth](https://discourse.julialang.org/u/neseth)\
**Replies:** 1\
**Last updated:** [January 5, 2019, 5:45pm UTC](https://discourse.julialang.org/t/random-error-unsupported-feature-hess/19306 "2019-01-05T17:45:51Z")

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Hello, I’m writing a code that have a user-defined gradient function, and solving it with Ipopt. The problem is that I need to run the file multiple times before it finally works. Most of the time it just gives me the…

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## [Flux seq2seq](https://discourse.julialang.org/t/flux-seq2seq/13783)

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**Author:** [@merckxiaan](https://discourse.julialang.org/u/merckxiaan)\
**Replies:** 12\
**Last updated:** [January 5, 2019, 12:52pm UTC](https://discourse.julialang.org/t/flux-seq2seq/13783 "2019-01-05T12:52:55Z")

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I don’t know whether this is the right place to ask but I’m trying to code a seq2seq model in Flux and I’ve got a couple of questions. The encoder creates the hidden state for the decoder, how can I pass this state to t…

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## [Multithreading and pmap](https://discourse.julialang.org/t/multithreading-and-pmap/19284)

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**Author:** [@gideonsimpson](https://discourse.julialang.org/u/gideonsimpson)\
**Replies:** 8\
**Last updated:** [January 5, 2019, 1:50am UTC](https://discourse.julialang.org/t/multithreading-and-pmap/19284 "2019-01-05T01:50:59Z")

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I have access to a new machine that has 2 x 20 core Xeon Gold CPUs which support multithreading. I was playing around with some simple pmap problems, and I was not seeing a performance jump when I tried going from 40 to…

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## [MPI.jl: Error building: recompile with -fPIC?](https://discourse.julialang.org/t/mpi-jl-error-building-recompile-with-fpic/19267)

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**Author:** [@samo](https://discourse.julialang.org/u/samo)\
**Replies:** 11\
**Last updated:** [January 4, 2019, 5:35pm UTC](https://discourse.julialang.org/t/mpi-jl-error-building-recompile-with-fpic/19267 "2019-01-04T17:35:24Z")

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Hi all, Before a complete re-installation of Julia in early December, MPI.jl worked for me. Now I cannot install the MPI.jl package anymore - it fails building: julia\> import Pkg; Pkg.add("MPI") Updating registry at …

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## [Segmentation fault using ArrayFire and @spawn](https://discourse.julialang.org/t/segmentation-fault-using-arrayfire-and-spawn/19266)

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**Author:** [@Noel\_Araujo](https://discourse.julialang.org/u/Noel_Araujo)\
**Replies:** 0\
**Last updated:** [January 4, 2019, 10:58am UTC](https://discourse.julialang.org/t/segmentation-fault-using-arrayfire-and-spawn/19266 "2019-01-04T10:58:47Z")

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Hello beautiful people, I have some process that can fit at my GPU memory, so to speed up, I was wondering if I could run parallel process (using Distributed). My hope was that Julia would do its magic, but I just got a…

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## [How to pass value to cut generation function?](https://discourse.julialang.org/t/how-to-pass-value-to-cut-generation-function/19226)

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**Author:** [@WangQuanmeng](https://discourse.julialang.org/u/WangQuanmeng)\
**Replies:** 7\
**Last updated:** [January 4, 2019, 4:20am UTC](https://discourse.julialang.org/t/how-to-pass-value-to-cut-generation-function/19226 "2019-01-04T04:20:00Z")

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Hi all, I am trying to write a user defined cut generation process. I meet the following problem, can you guys help me on this? Suppose I am solving an optimization problem, whose input is a matrix W. I formulate the …

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## [Julia code for the book Reinforcement Learning An Introduction(2nd)](https://discourse.julialang.org/t/julia-code-for-the-book-reinforcement-learning-an-introduction-2nd/19190)

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**Author:** [@findmyway](https://discourse.julialang.org/u/findmyway)\
**Replies:** 0\
**Last updated:** [January 2, 2019, 11:46am UTC](https://discourse.julialang.org/t/julia-code-for-the-book-reinforcement-learning-an-introduction-2nd/19190 "2019-01-02T11:46:55Z")

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Recently I reproduced most figures on the book Reinforcement Learning An Introduction in Julia. I hope it is helpful to those who are interested in both Julia and RL. If you also have a background in Python, I’d sugge…

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## [Presentation on effective use of CUDAnative/CuArrays](https://discourse.julialang.org/t/presentation-on-effective-use-of-cudanative-cuarrays/18919)

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**Author:** [@maleadt](https://discourse.julialang.org/u/maleadt)\
**Replies:** 7\
**Last updated:** [January 3, 2019, 7:28am UTC](https://discourse.julialang.org/t/presentation-on-effective-use-of-cudanative-cuarrays/18919 "2019-01-03T07:28:17Z")

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Since our GPU stack is pretty ill-documented, I figured it can’t hurt to cross-post any content there is. Here’s a recent presentation of mine that explains how the relevant packages work, with demos, as well as tips/tri…

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## [JuMP Error: "Unexpected object missing in nonlinear expression"](https://discourse.julialang.org/t/jump-error-unexpected-object-missing-in-nonlinear-expression/19151)

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**Author:** [@krenova](https://discourse.julialang.org/u/krenova)\
**Replies:** 3\
**Last updated:** [January 1, 2019, 11:29am UTC](https://discourse.julialang.org/t/jump-error-unexpected-object-missing-in-nonlinear-expression/19151 "2019-01-01T11:29:19Z")

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Hi, I’ve been trying to perform a MLE procedure with JuMP but constantly run into an error. A snippet of my code is as follows: using Distributions using JuMP norm\_cdf(x) = cdf(Normal(), x) #where Normal() is from Dis…

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## [Problem with Violin and Boxplots ](https://discourse.julialang.org/t/problem-with-violin-and-boxplots/19149)

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**Author:** [@daler6](https://discourse.julialang.org/u/daler6)\
**Replies:** 3\
**Last updated:** [January 1, 2019, 6:00am UTC](https://discourse.julialang.org/t/problem-with-violin-and-boxplots/19149 "2019-01-01T06:00:21Z")

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I am fairly new to Julia, so I have been working through the Plots tutorial at Tutorial · Plots. I run into a number of problems in the first example under " Using Series Recipes". Specifically, I enter the code provided…

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## [Probabilistic programming repositories](https://discourse.julialang.org/t/probabilistic-programming-repositories/19125)

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**Author:** [@cscherrer](https://discourse.julialang.org/u/cscherrer)\
**Replies:** 8\
**Last updated:** [December 31, 2018, 6:47pm UTC](https://discourse.julialang.org/t/probabilistic-programming-repositories/19125 "2018-12-31T18:47:44Z")

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There seem to be quite a few Julia repositories related to probabilistic programming. Here are the ones I’m aware of that have been updated in 2018 - anything I’m missing? Any experiences using these or comparing/contra…

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## [DOOM fire animation](https://discourse.julialang.org/t/doom-fire-animation/19100)

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**Author:** [@gdkrmr](https://discourse.julialang.org/u/gdkrmr)\
**Replies:** 4\
**Last updated:** [December 31, 2018, 12:42pm UTC](https://discourse.julialang.org/t/doom-fire-animation/19100 "2018-12-31T12:42:19Z")

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Just for fun, I recreated the fire animation from DOOM in Julia: https://gist.github.com/gdkrmr/ea4e7259f58e1504dbc46538dc4ad0e5 Code was adapted from here: http://fabiensanglard.net/doom\_fire\_psx/

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## [Help on decision to choose Julia for my convex optimization project](https://discourse.julialang.org/t/help-on-decision-to-choose-julia-for-my-convex-optimization-project/19107)

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**Author:** [@Toxmi](https://discourse.julialang.org/u/Toxmi)\
**Replies:** 2\
**Last updated:** [December 30, 2018, 4:29pm UTC](https://discourse.julialang.org/t/help-on-decision-to-choose-julia-for-my-convex-optimization-project/19107 "2018-12-30T16:29:32Z")

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I have 2 weeks for my term project (basically simulation of convex optimization problem based on a paper). I’m quite comfortable with Matlab and Python and know CVX. However, I wanted to use this chance and dive into Jul…

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## [Mu\_target not working for ipopt](https://discourse.julialang.org/t/mu-target-not-working-for-ipopt/19087)

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**Author:** [@pedroborgesmelo](https://discourse.julialang.org/u/pedroborgesmelo)\
**Replies:** 1\
**Last updated:** [December 29, 2018, 2:03pm UTC](https://discourse.julialang.org/t/mu-target-not-working-for-ipopt/19087 "2018-12-29T14:03:47Z")

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Hello guys! Previously, Ipopt was accepting my mu\_target option. With problems created in the standard manner you see on the internet. Now, it is not. The difference is that now for some specific reason I’m creating the…

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## [3D Isosurface](https://discourse.julialang.org/t/3d-isosurface/19042)

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**Author:** [@CrocoDuck](https://discourse.julialang.org/u/CrocoDuck)\
**Replies:** 4\
**Last updated:** [December 28, 2018, 7:02pm UTC](https://discourse.julialang.org/t/3d-isosurface/19042 "2018-12-28T19:02:30Z")

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Hi guys! I would like to make nice plots of acoustic modes in a rectangular room by making use of isosurfaces. Below you can see a bunch of examples of what I am aiming for. I did those with Matlab few years ago. I …

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## [Issues with shared memory parallel k-means implementation](https://discourse.julialang.org/t/issues-with-shared-memory-parallel-k-means-implementation/18894)

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**Author:** [@novoselrok](https://discourse.julialang.org/u/novoselrok)\
**Replies:** 1\
**Last updated:** [December 28, 2018, 4:34am UTC](https://discourse.julialang.org/t/issues-with-shared-memory-parallel-k-means-implementation/18894 "2018-12-28T04:34:25Z")

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Hello. I’m trying to implement the k-means algorithm using the @threads macro. I’ve also implemented a sequential program for comparison, but it always run faster than the parallel version. The changes to the parallel a…

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## [SatelliteToolbox.jl v0.5.0 has been tagged](https://discourse.julialang.org/t/satellitetoolbox-jl-v0-5-0-has-been-tagged/19039)

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**Author:** [@Ronis\_BR](https://discourse.julialang.org/u/Ronis_BR)\
**Replies:** 0\
**Last updated:** [December 27, 2018, 5:08pm UTC](https://discourse.julialang.org/t/satellitetoolbox-jl-v0-5-0-has-been-tagged/19039 "2018-12-27T17:08:30Z")

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Hi guys! I have just tagged the v0.5.0 of SatelliteToolbox.jl. This is a huge release (I think the biggest one of this package) that contains almost 2 months of work. Here is a summary of the changes (for a complete lis…

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## [Request for examples: Systems of nonlinear equations that have jacobians with special structure](https://discourse.julialang.org/t/request-for-examples-systems-of-nonlinear-equations-that-have-jacobians-with-special-structure/18936)

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**Author:** [@pkofod](https://discourse.julialang.org/u/pkofod)\
**Replies:** 1\
**Last updated:** [December 23, 2018, 8:43pm UTC](https://discourse.julialang.org/t/request-for-examples-systems-of-nonlinear-equations-that-have-jacobians-with-special-structure/18936 "2018-12-23T20:43:31Z")

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I’m changing some things in NLsolve.jl, in particular the possibility to chose the solver than solves the linear system of equations to determine the step direction. This means that if you have a package MySpecialLinsolv…

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## [Styling plotted maps](https://discourse.julialang.org/t/styling-plotted-maps/18673)

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**Author:** [@juliusgeo](https://discourse.julialang.org/u/juliusgeo)\
**Replies:** 5\
**Last updated:** [December 23, 2018, 5:55pm UTC](https://discourse.julialang.org/t/styling-plotted-maps/18673 "2018-12-23T17:55:32Z")

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Hi all, I am working on developing a package to create really nice looking plots of maps that are in OSM format. I currently am using Winston.jl, and just have a big dictionary containing all the styles that can be chan…

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## [How to use distance\_transform in Images.jl](https://discourse.julialang.org/t/how-to-use-distance-transform-in-images-jl/18861)

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**Author:** [@wrgr](https://discourse.julialang.org/u/wrgr)\
**Replies:** 2\
**Last updated:** [December 21, 2018, 8:21pm UTC](https://discourse.julialang.org/t/how-to-use-distance-transform-in-images-jl/18861 "2018-12-21T20:21:52Z")

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Tried to use distance\_transform(rand(Bool, 500, 500)) from Images.jl, but got MethodError: no method matching distance\_transform(::Array{Bool,2}) Closest candidates are: distance\_transform(!Matched::AbstractArray{Ca…

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