# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=538

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

**Page:** 539

---

## [Gurobi 8.0](https://discourse.julialang.org/t/gurobi-8-0/10606)

<div class="topic-metadata">

**Author:** [@Frank\_Kampas](https://discourse.julialang.org/u/Frank_Kampas)\
**Replies:** 2\
**Last updated:** [April 29, 2018, 3:54pm UTC](https://discourse.julialang.org/t/gurobi-8-0/10606 "2018-04-29T15:54:55Z")

</div>

What’s the process to switch to the new Gurobi release (8.0) ?

---

## [Very Slow Compilation for Sensitivity Analysis](https://discourse.julialang.org/t/very-slow-compilation-for-sensitivity-analysis/10598)

<div class="topic-metadata">

**Author:** [@ckfinite](https://discourse.julialang.org/u/ckfinite)\
**Replies:** 3\
**Last updated:** [April 28, 2018, 8:01pm UTC](https://discourse.julialang.org/t/very-slow-compilation-for-sensitivity-analysis/10598 "2018-04-28T20:01:20Z")

</div>

I’m working on an application that performs optimization of a complex ODE by iteratively optimizing over the linearized system. The optimization works fine, but sensitivity analysis of the ODE has very strange performanc…

---

## [A proposal for \`describe\` of a DataFrame](https://discourse.julialang.org/t/a-proposal-for-describe-of-a-dataframe/10254)

<div class="topic-metadata">

**Author:** [@pdeffebach](https://discourse.julialang.org/u/pdeffebach)\
**Replies:** 17\
**Last updated:** [April 28, 2018, 9:05am UTC](https://discourse.julialang.org/t/a-proposal-for-describe-of-a-dataframe/10254 "2018-04-28T09:05:38Z")

</div>

I am interested in making DataFrames as functional as R and Stata’s ecosystem. So far, I am really impressed with the data munging and processing ecosystem. I think a combination of DataFrames, DataFramesMeta, and Lazy r…

---

## [GLM.jl module : 1 test failed](https://discourse.julialang.org/t/glm-jl-module-1-test-failed/10567)

<div class="topic-metadata">

**Author:** [@hung-q-ngo](https://discourse.julialang.org/u/hung-q-ngo)\
**Replies:** 3\
**Last updated:** [April 28, 2018, 8:05am UTC](https://discourse.julialang.org/t/glm-jl-module-1-test-failed/10567 "2018-04-28T08:05:57Z")

</div>

Hello, any idea what I did wrong here? (I have julia version 0.6.2, and latest GLM.jl package). I was running ~/repos/git/GLM.jl/test$ julia runtests.jl and got WARNING: Method definition ==(Base.Nullable{S}, Base.Nul…

---

## [Sampling Multiple samples from NormalInverseGamma distribution](https://discourse.julialang.org/t/sampling-multiple-samples-from-normalinversegamma-distribution/10575)

<div class="topic-metadata">

**Author:** [@v-i-s-h](https://discourse.julialang.org/u/v-i-s-h)\
**Replies:** 2\
**Last updated:** [April 27, 2018, 4:26pm UTC](https://discourse.julialang.org/t/sampling-multiple-samples-from-normalinversegamma-distribution/10575 "2018-04-27T16:26:25Z")

</div>

Hi, I’m trying to sample multiple samples from a NormalInversaGamma distribution. I was using rand() function with two arguments, but is getting the following error: julia\> using ConjugatePriors julia\> D = ConjugatePri…

---

## [\`precision\` of a \`BigFloat\` number returning an \`Int32\` on Windows 10](https://discourse.julialang.org/t/precision-of-a-bigfloat-number-returning-an-int32-on-windows-10/10292)

<div class="topic-metadata">

**Author:** [@Kolaru](https://discourse.julialang.org/u/Kolaru)\
**Replies:** 5\
**Last updated:** [April 27, 2018, 12:00am UTC](https://discourse.julialang.org/t/precision-of-a-bigfloat-number-returning-an-int32-on-windows-10/10292 "2018-04-27T00:00:55Z")

</div>

I recently encountered a strange comportment on my machine : julia\> typeof(precision(2.2)) Int64 julia\> typeof(precision(BigFloat(2.2))) Int32 I tried the same code in JuliaBox and there it returns an Int64 both time, …

---

## [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…

[Previous page](https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=537)

[Next page](https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=539)