# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?page=539

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

**Page:** 540

---

## [Local Parallel Processing Benchmark Advice](https://discourse.julialang.org/t/local-parallel-processing-benchmark-advice/10519)

<div class="topic-metadata">

**Author:** [@iwelch](https://discourse.julialang.org/u/iwelch)\
**Replies:** 2\
**Last updated:** [April 26, 2018, 2:32pm UTC](https://discourse.julialang.org/t/local-parallel-processing-benchmark-advice/10519 "2018-04-26T14:32:14Z")

</div>

ok, I spent a few days benchmarking various versions of local multiprocessing under julia 0.6.2, with 4-core and 8-core intel processors. The results are at the rear of http://julia.cookbook.tips/doku.php?id=parallel . …

---

## [Optim.jl optimize over Distances.jl metric](https://discourse.julialang.org/t/optim-jl-optimize-over-distances-jl-metric/10542)

<div class="topic-metadata">

**Author:** [@mcbaron](https://discourse.julialang.org/u/mcbaron)\
**Replies:** 4\
**Last updated:** [April 26, 2018, 11:45am UTC](https://discourse.julialang.org/t/optim-jl-optimize-over-distances-jl-metric/10542 "2018-04-26T11:45:12Z")

</div>

Hello all! I’m wondering what’s the most efficient way to go about optimizing over a specific distance metric. As of right now, I have two vectors, x, y and bhattacharyya(x, y) as loaded from Distances.jl. I’d like to …

---

## [Registering Analytical Derivative with ReverseDiff/ForwardDiff](https://discourse.julialang.org/t/registering-analytical-derivative-with-reversediff-forwarddiff/10543)

<div class="topic-metadata">

**Author:** [@crinders](https://discourse.julialang.org/u/crinders)\
**Replies:** 4\
**Last updated:** [April 25, 2018, 7:56pm UTC](https://discourse.julialang.org/t/registering-analytical-derivative-with-reversediff-forwarddiff/10543 "2018-04-25T19:56:48Z")

</div>

Is there a way to register a derivative function similar to JuMP’s usage in ForwardDiff or ReverseDiff? I have a small function which solves a simple optimization problem using svd, which isn’t automatically differentiat…

---

## [Baffling addprocs() with @everywhere](https://discourse.julialang.org/t/baffling-addprocs-with-everywhere/10464)

<div class="topic-metadata">

**Author:** [@iwelch](https://discourse.julialang.org/u/iwelch)\
**Replies:** 17\
**Last updated:** [April 24, 2018, 10:33pm UTC](https://discourse.julialang.org/t/baffling-addprocs-with-everywhere/10464 "2018-04-24T22:33:37Z")

</div>

Can addprocs() function only be used at the start of code? @everywhere function samplefun(x::Real) 2.0 end addprocs(2) ## if here, it does not work @everywhere M= 10 sa = SharedArray{Float64}(M) s= @sync @parallel…

---

## [Slow generation of a large LP model in JuMP](https://discourse.julialang.org/t/slow-generation-of-a-large-lp-model-in-jump/3034)

<div class="topic-metadata">

**Author:** [@NiclasMattsson](https://discourse.julialang.org/u/NiclasMattsson)\
**Replies:** 11\
**Last updated:** [April 24, 2018, 10:24pm UTC](https://discourse.julialang.org/t/slow-generation-of-a-large-lp-model-in-jump/3034 "2018-04-24T22:24:14Z")

</div>

\[Wall of text incoming, beware!\] I’m a Julia novice and have been playing around with JuMP over the last month or so. All my small scale test models worked beautifully, so I finally decided to dive into the deep end of …

---

## [Smallest Eigenvalue of a Moler Matrix](https://discourse.julialang.org/t/smallest-eigenvalue-of-a-moler-matrix/10510)

<div class="topic-metadata">

**Author:** [@Hans\_W\_Borchers](https://discourse.julialang.org/u/Hans_W_Borchers)\
**Replies:** 1\
**Last updated:** [April 24, 2018, 5:35pm UTC](https://discourse.julialang.org/t/smallest-eigenvalue-of-a-moler-matrix/10510 "2018-04-24T17:35:38Z")

</div>

For some (strange) reasons I got interested in the smallest eigenvalue of some larger Moler matrices. using MatrixDepot N = 100; A = matrixdepot("moler", 100); D, V = eig(A); D ## -7.60989e-16 2.25006 ... 159.39 439.…

---

## [Open Community Runtime](https://discourse.julialang.org/t/open-community-runtime/10500)

<div class="topic-metadata">

**Author:** [@johnh](https://discourse.julialang.org/u/johnh)\
**Replies:** 0\
**Last updated:** [April 24, 2018, 5:30am UTC](https://discourse.julialang.org/t/open-community-runtime/10500 "2018-04-24T05:30:15Z")

</div>

Over on the singularity list, I came across mention of OCR https://wiki.modelado.org/Open\_Community\_Runtime Described as a task-based paradigm along the lines of Stanford’s Legion or Cray’s Chapel. It strikes me as it…

---

## [Suggestion of workflow to modify composite object in parallel](https://discourse.julialang.org/t/suggestion-of-workflow-to-modify-composite-object-in-parallel/10495)

<div class="topic-metadata">

**Author:** [@bbrunaud](https://discourse.julialang.org/u/bbrunaud)\
**Replies:** 3\
**Last updated:** [April 24, 2018, 4:47am UTC](https://discourse.julialang.org/t/suggestion-of-workflow-to-modify-composite-object-in-parallel/10495 "2018-04-24T04:47:25Z")

</div>

Hello, I have an object composed of other objects inside, (Graph, Nodes). I want to run an operation on the nodes that modifies the node, adjacent nodes, and the graph. What is the best workflow to do it in parallel. I …

---

## [Solving system equations using Knitro](https://discourse.julialang.org/t/solving-system-equations-using-knitro/10490)

<div class="topic-metadata">

**Author:** [@LinOslo](https://discourse.julialang.org/u/LinOslo)\
**Replies:** 3\
**Last updated:** [April 23, 2018, 8:51pm UTC](https://discourse.julialang.org/t/solving-system-equations-using-knitro/10490 "2018-04-23T20:51:01Z")

</div>

I’m solving a system equation using KNITRO. For example the system takes the form: x+3yˆ3-7+18=0 sin(yexp(x)-1)=0 I want to use self-defined functions (instead of using ‘in-line’ functions as in JuMP). Therefore in Ju…

---

## [Determine instantaneous frequency (IF) with Julia](https://discourse.julialang.org/t/determine-instantaneous-frequency-if-with-julia/5529)

<div class="topic-metadata">

**Author:** [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Replies:** 5\
**Last updated:** [April 18, 2018, 1:15am UTC](https://discourse.julialang.org/t/determine-instantaneous-frequency-if-with-julia/5529 "2018-04-18T01:15:25Z")

</div>

Hello, I am looking for a way to determine the instantaneous frequency of a signal (filtered BDLC motor phase voltage) to determine the speed of this motor. The sampling frequency is 8 kHz, the max, electrical frequenc…

---

## [Is infinite figure zoom possible (i.e. callback to refresh figure data)?](https://discourse.julialang.org/t/is-infinite-figure-zoom-possible-i-e-callback-to-refresh-figure-data/10468)

<div class="topic-metadata">

**Author:** [@NickNack](https://discourse.julialang.org/u/NickNack)\
**Replies:** 5\
**Last updated:** [April 21, 2018, 11:58pm UTC](https://discourse.julialang.org/t/is-infinite-figure-zoom-possible-i-e-callback-to-refresh-figure-data/10468 "2018-04-21T23:58:59Z")

</div>

Several of the backends to Plots.jl provide interactive pan & zoom. However (as far as I can tell) they only work with the original figure data, so the figure looks pixelized and ugly when zoomed in sufficiently. Is ther…

---

## [Unexpected behavior of Query.jl @map](https://discourse.julialang.org/t/unexpected-behavior-of-query-jl-map/10474)

<div class="topic-metadata">

**Author:** [@SebastianM-C](https://discourse.julialang.org/u/SebastianM-C)\
**Replies:** 0\
**Last updated:** [April 21, 2018, 11:27pm UTC](https://discourse.julialang.org/t/unexpected-behavior-of-query-jl-map/10474 "2018-04-21T23:27:35Z")

</div>

I tried to call a function for each selected row with Query.jl with the following code: test = DataFrame() test\[:a\] = \[1,2,3,4\] test\[:b\] = \[1,1,2,3\] test |\> @filter(\_.b==1) |\> @map(println(\_.a)) and I noticed that in J…

---

## [Using Survey/Inverse Probability Weights in Regression](https://discourse.julialang.org/t/using-survey-inverse-probability-weights-in-regression/10444)

<div class="topic-metadata">

**Author:** [@jhartma](https://discourse.julialang.org/u/jhartma)\
**Replies:** 3\
**Last updated:** [April 19, 2018, 8:45pm UTC](https://discourse.julialang.org/t/using-survey-inverse-probability-weights-in-regression/10444 "2018-04-19T20:45:57Z")

</div>

Hi, I hope the answer is not too obvious as I am new to Julia. I want to do some regressions with a weighted sample. At the moment I use the GLM package and I saw there are ProbabilityWeights, but I haven’t figured out …

---

## [When should a package be added to JuliaStats](https://discourse.julialang.org/t/when-should-a-package-be-added-to-juliastats/10380)

<div class="topic-metadata">

**Author:** [@colintbowers](https://discourse.julialang.org/u/colintbowers)\
**Replies:** 10\
**Last updated:** [April 19, 2018, 11:53am UTC](https://discourse.julialang.org/t/when-should-a-package-be-added-to-juliastats/10380 "2018-04-19T11:53:03Z")

</div>

Hi all, I was wondering what the procedure is for deciding if a package should be added to JuliaStats, and, if so, how it is done. I’ve got two packages that are possibly suitable, DependentBootstrap, and ForecastEval. …

---

## [Different ways to declare a constraint](https://discourse.julialang.org/t/different-ways-to-declare-a-constraint/10415)

<div class="topic-metadata">

**Author:** [@jayce\_ram](https://discourse.julialang.org/u/jayce_ram)\
**Replies:** 3\
**Last updated:** [April 19, 2018, 9:58am UTC](https://discourse.julialang.org/t/different-ways-to-declare-a-constraint/10415 "2018-04-19T09:58:36Z")

</div>

Hello, I’m taking my first steps into Julia and I’m trying to modelate a LP. I wrote the following constraint: @constraint(m, ctte\_equilibre\[r in set\_regions, tec in tech\_by\_site\[r\], dy in div\_years, y in years, t in t…

---

## [Managing unnecessary 0's in JuMP](https://discourse.julialang.org/t/managing-unnecessary-0s-in-jump/10414)

<div class="topic-metadata">

**Author:** [@ExpandingMan](https://discourse.julialang.org/u/ExpandingMan)\
**Replies:** 4\
**Last updated:** [April 18, 2018, 4:27pm UTC](https://discourse.julialang.org/t/managing-unnecessary-0s-in-jump/10414 "2018-04-18T16:27:37Z")

</div>

I have a rather ugly quadratic objective function that requires a fair amount of manipulation of variables, and I suspect that one of the things that’s making this process incredibly slow is that I have lots of GenericAf…

---

## [Error when using "too many" workers](https://discourse.julialang.org/t/error-when-using-too-many-workers/10413)

<div class="topic-metadata">

**Author:** [@bisraelsen](https://discourse.julialang.org/u/bisraelsen)\
**Replies:** 10\
**Last updated:** [April 18, 2018, 3:14pm UTC](https://discourse.julialang.org/t/error-when-using-too-many-workers/10413 "2018-04-18T15:14:59Z")

</div>

Hi, I have been running code in parallel using julia -p200 for a while. Now I am using a cloud server that has: CPU(s) 96 Cores Per Socket 24 Sockets 2 By my calculat…

---

## [ANN: EmpiricalCDFs.jl](https://discourse.julialang.org/t/ann-empiricalcdfs-jl/10411)

<div class="topic-metadata">

**Author:** [@jlapeyre](https://discourse.julialang.org/u/jlapeyre)\
**Replies:** 0\
**Last updated:** [April 18, 2018, 11:04am UTC](https://discourse.julialang.org/t/ann-empiricalcdfs-jl/10411 "2018-04-18T11:04:43Z")

</div>

EmpiricalCDFs.jl EmpiricalCDFs implements empirical CDFs; building, evaluating, random sampling, evaluating the inverse, etc. It is useful especially for examining the tail of the CDF obtained from streaming a large num…

---

## [JLD disk space usage](https://discourse.julialang.org/t/jld-disk-space-usage/10397)

<div class="topic-metadata">

**Author:** [@gideonsimpson](https://discourse.julialang.org/u/gideonsimpson)\
**Replies:** 1\
**Last updated:** [April 18, 2018, 9:36am UTC](https://discourse.julialang.org/t/jld-disk-space-usage/10397 "2018-04-18T09:36:07Z")

</div>

If I have data stored in a JLD file is there a way to analyze it to see which variables in the .jld are taking up which fraction of the disk space?

---

## [Is it possible that passing user defined gradient slows down the solver](https://discourse.julialang.org/t/is-it-possible-that-passing-user-defined-gradient-slows-down-the-solver/10311)

<div class="topic-metadata">

**Author:** [@Ksun46](https://discourse.julialang.org/u/Ksun46)\
**Replies:** 5\
**Last updated:** [April 18, 2018, 2:34am UTC](https://discourse.julialang.org/t/is-it-possible-that-passing-user-defined-gradient-slows-down-the-solver/10311 "2018-04-18T02:34:31Z")

</div>

Hi all, I am using JuMP with Ipopt and encounter this problem. For example, I have a constraint looks like x^2 + y^2 \<= 1. Originally I just add this constraints to the model. But when I try to define a function f(x, y)…

---

## [Line Color Sequence in Plots.jl](https://discourse.julialang.org/t/line-color-sequence-in-plots-jl/10390)

<div class="topic-metadata">

**Author:** [@gideonsimpson](https://discourse.julialang.org/u/gideonsimpson)\
**Replies:** 1\
**Last updated:** [April 17, 2018, 3:06pm UTC](https://discourse.julialang.org/t/line-color-sequence-in-plots-jl/10390 "2018-04-17T15:06:08Z")

</div>

For Plots.jl, is there a way to manually access/iterate through the default line color sequence? I know that in the latest matplotlib, it’s default sequence is labeled C0, C1, etc. Is there an analog here?

---

## [DataFramesMeta @linq does not dispatch to StatsBase.mean?](https://discourse.julialang.org/t/dataframesmeta-linq-does-not-dispatch-to-statsbase-mean/10343)

<div class="topic-metadata">

**Author:** [@floswald](https://discourse.julialang.org/u/floswald)\
**Replies:** 2\
**Last updated:** [April 15, 2018, 8:29am UTC](https://discourse.julialang.org/t/dataframesmeta-linq-does-not-dispatch-to-statsbase-mean/10343 "2018-04-15T08:29:44Z")

</div>

I have this issue with DataFramesMeta using DataFrames, DataFramesMeta, StatsBase julia\> d = DataFrame(a=1:10,b = 2.0 \* (1:10),w=Weights(\[1,zeros(9)...\])) 10×3 DataFrames.DataFrame │ Row │ a │ b │ w │ ├─────┼────…

---

## [ANN: DataDeps.jl: BinDeps for Data](https://discourse.julialang.org/t/ann-datadeps-jl-bindeps-for-data/8457)

<div class="topic-metadata">

**Author:** [@oxinabox](https://discourse.julialang.org/u/oxinabox)\
**Replies:** 16\
**Last updated:** [April 17, 2018, 5:50am UTC](https://discourse.julialang.org/t/ann-datadeps-jl-bindeps-for-data/8457 "2018-04-17T05:50:31Z")

</div>

I’ve now released DataDeps.jl, which is a package for automating the setup of data that a package or scientific script might depend upon. See the Repository: https://github.com/oxinabox/DataDeps.jl and the demo blog p…

---

## [Accessing the root node solution](https://discourse.julialang.org/t/accessing-the-root-node-solution/10371)

<div class="topic-metadata">

**Author:** [@varun7rs](https://discourse.julialang.org/u/varun7rs)\
**Replies:** 6\
**Last updated:** [April 17, 2018, 5:16am UTC](https://discourse.julialang.org/t/accessing-the-root-node-solution/10371 "2018-04-17T05:16:05Z")

</div>

I’m working on a heuristic that takes in a fractional solution and applies randomised rounding operations to get a feasible solution. In order to obtain the fractional solution, I tried solving the LP but the computation…

---

## [Hard-SVM in Julia](https://discourse.julialang.org/t/hard-svm-in-julia/10326)

<div class="topic-metadata">

**Author:** [@Paul\_McVay](https://discourse.julialang.org/u/Paul_McVay)\
**Replies:** 2\
**Last updated:** [April 16, 2018, 7:47pm UTC](https://discourse.julialang.org/t/hard-svm-in-julia/10326 "2018-04-16T19:47:15Z")

</div>

Is there any library that implements hard-SVM directly instead of soft-SVM? I looked at several libraries and they all seem to implement C-SVM or nu-SVM, something with the slack variables.

---

## [Axes attributes (labels, limits) not working in 3d plots](https://discourse.julialang.org/t/axes-attributes-labels-limits-not-working-in-3d-plots/10341)

<div class="topic-metadata">

**Author:** [@leoll2](https://discourse.julialang.org/u/leoll2)\
**Replies:** 4\
**Last updated:** [April 15, 2018, 5:05pm UTC](https://discourse.julialang.org/t/axes-attributes-labels-limits-not-working-in-3d-plots/10341 "2018-04-15T17:05:20Z")

</div>

I need to modify the labels and the range limits of the axes of my graph. It should be an easy task with Plots, indeed it is for 2d graphs. However, the same code doesn’t work when the dimensions become three (3d). I’m …

---

## [How does juliaDB store data on disk? Is it a row store or a column store?](https://discourse.julialang.org/t/how-does-juliadb-store-data-on-disk-is-it-a-row-store-or-a-column-store/10339)

<div class="topic-metadata">

**Author:** [@Steven\_Sagaert](https://discourse.julialang.org/u/Steven_Sagaert)\
**Replies:** 1\
**Last updated:** [April 15, 2018, 6:32am UTC](https://discourse.julialang.org/t/how-does-juliadb-store-data-on-disk-is-it-a-row-store-or-a-column-store/10339 "2018-04-15T06:32:07Z")

</div>

What is the storage format? By column store I mean Column-oriented DBMS - Wikipedia

---

## [How to create a huge set of variables (500k or more) in JUMP](https://discourse.julialang.org/t/how-to-create-a-huge-set-of-variables-500k-or-more-in-jump/10325)

<div class="topic-metadata">

**Author:** [@jayce\_ram](https://discourse.julialang.org/u/jayce_ram)\
**Replies:** 4\
**Last updated:** [April 15, 2018, 5:26am UTC](https://discourse.julialang.org/t/how-to-create-a-huge-set-of-variables-500k-or-more-in-jump/10325 "2018-04-15T05:26:45Z")

</div>

Hello everybody, I’m completely new in Jump and I have a very large LP to solve. The number of variables depend of the input data. My variables are too nested, for example, for each given installation, there’s an associa…

---

## [Is it possible to use "supertype" in function type declaration](https://discourse.julialang.org/t/is-it-possible-to-use-supertype-in-function-type-declaration/10320)

<div class="topic-metadata">

**Author:** [@Fred](https://discourse.julialang.org/u/Fred)\
**Replies:** 9\
**Last updated:** [April 13, 2018, 12:38pm UTC](https://discourse.julialang.org/t/is-it-possible-to-use-supertype-in-function-type-declaration/10320 "2018-04-13T12:38:30Z")

</div>

Hi, When I process strings in Julia, I have often a problem with the ::String type because sometime my function need a String and sometime a SubString{String} and I have this error no method matching processData(::Sub…

---

## [MultiResolutionInterators.jl: Tools for working with data that has macro-scale hierachical structure, where you don't always care about some of the levels](https://discourse.julialang.org/t/multiresolutioninterators-jl-tools-for-working-with-data-that-has-macro-scale-hierachical-structure-where-you-dont-always-care-about-some-of-the-levels/10315)

<div class="topic-metadata">

**Author:** [@oxinabox](https://discourse.julialang.org/u/oxinabox)\
**Replies:** 1\
**Last updated:** [April 13, 2018, 10:22am UTC](https://discourse.julialang.org/t/multiresolutioninterators-jl-tools-for-working-with-data-that-has-macro-scale-hierachical-structure-where-you-dont-always-care-about-some-of-the-levels/10315 "2018-04-13T10:22:23Z")

</div>

I wanted to share this that I am working on right now. (Not yet registered) https://github.com/oxinabox/MultiResolutionIterators.jl I’m making it as a part in my reengineering of CorpusLoaders.jl. Basically a lot of …

[Previous page](https://discourse.julialang.org/c/domain/10.md?page=538)

[Next page](https://discourse.julialang.org/c/domain/10.md?page=540)