# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1088

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

**Page:** 1089

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## [Warning: type does not exist in workspace; reconstructing](https://discourse.julialang.org/t/warning-type-does-not-exist-in-workspace-reconstructing/78232)

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**Author:** [@Amro](https://discourse.julialang.org/u/Amro)\
**Replies:** 1\
**Last updated:** [March 22, 2022, 8:11am UTC](https://discourse.julialang.org/t/warning-type-does-not-exist-in-workspace-reconstructing/78232 "2022-03-22T08:11:22Z")

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I was using the below code to create .jld2 file containing an instance Sim of structure Simulation include("./SimulationStructure.jl"); function appFunction() Sim = Simulation(); io = open("$(@\_\_DIR\_\_)/generatedElements…

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## [Replace a JuMP variable by a number](https://discourse.julialang.org/t/replace-a-jump-variable-by-a-number/78158)

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**Author:** [@wujinq](https://discourse.julialang.org/u/wujinq)\
**Replies:** 5\
**Last updated:** [March 23, 2022, 4:58pm UTC](https://discourse.julialang.org/t/replace-a-jump-variable-by-a-number/78158 "2022-03-23T16:58:41Z")

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I have a large optimization problem written in JuMP.jl and do not get the expected results. To debug my program, I want to replace the variables in constraints by their values found by an analytical calculation. That is,…

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## [Choose different behavior depending on possible arguments of user-defined function](https://discourse.julialang.org/t/choose-different-behavior-depending-on-possible-arguments-of-user-defined-function/78321)

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**Author:** [@jules](https://discourse.julialang.org/u/jules)\
**Replies:** 6\
**Last updated:** [March 23, 2022, 4:39pm UTC](https://discourse.julialang.org/t/choose-different-behavior-depending-on-possible-arguments-of-user-defined-function/78321 "2022-03-23T16:39:38Z")

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A pattern I encounter every once in a while is that I want a user to be able to pass a function to one of my package’s functions. Then I’d like to do different things with this function depending on what arguments it can…

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## [Differentialequations.jl - Solving ODE with time dependent parameter allocation friendly](https://discourse.julialang.org/t/differentialequations-jl-solving-ode-with-time-dependent-parameter-allocation-friendly/78284)

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**Author:** [@mrVeng](https://discourse.julialang.org/u/mrVeng)\
**Replies:** 2\
**Last updated:** [March 23, 2022, 4:08pm UTC](https://discourse.julialang.org/t/differentialequations-jl-solving-ode-with-time-dependent-parameter-allocation-friendly/78284 "2022-03-23T16:08:14Z")

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Dear all, I am using DifferentialEquations.jl to solve a standard SEIR Model. The ODE looks like this: using DifferentialEquations using BenchmarkTools, UnPack function seir\_ode!(du,u,p,t) (S,E,I,R,C) = u (β,γ…

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## [DeepLearning Visualization / interpretation methods](https://discourse.julialang.org/t/deeplearning-visualization-interpretation-methods/78334)

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**Author:** [@lgmendes](https://discourse.julialang.org/u/lgmendes)\
**Replies:** 0\
**Last updated:** [March 23, 2022, 2:26pm UTC](https://discourse.julialang.org/t/deeplearning-visualization-interpretation-methods/78334 "2022-03-23T14:26:13Z")

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Hi, Does anyone know if there is any implementation of GradCam and or other Visualization techniques of DeepLearning models? I found an old package that does not work with the Flux+Zygote ( https://github.com/avik-pal/…

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## [RAM needed to initialise large matrices](https://discourse.julialang.org/t/ram-needed-to-initialise-large-matrices/78302)

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**Author:** [@fipelle](https://discourse.julialang.org/u/fipelle)\
**Replies:** 31\
**Last updated:** [March 23, 2022, 1:50pm UTC](https://discourse.julialang.org/t/ram-needed-to-initialise-large-matrices/78302 "2022-03-23T13:50:00Z")

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Hi, I have a basic doubt on memory management. I am currently working on a high-dimensional problem in which I would need to use a handful of matrices with size 500,000 x 500,000. I was wondering how much ram is needed t…

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## [Updated CSV reader benchmarks?](https://discourse.julialang.org/t/updated-csv-reader-benchmarks/78331)

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**Author:** [@Philogicatician](https://discourse.julialang.org/u/Philogicatician)\
**Replies:** 4\
**Last updated:** [March 23, 2022, 1:32pm UTC](https://discourse.julialang.org/t/updated-csv-reader-benchmarks/78331 "2022-03-23T13:32:30Z")

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An update for Julia 1.7.2 on Jupyter notebooks:

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## [CSV Reader Benchmarks: Julia Reads CSVs 10-20x Faster than Python and R](https://discourse.julialang.org/t/csv-reader-benchmarks-julia-reads-csvs-10-20x-faster-than-python-and-r/41974)

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**Author:** [@oheil](https://discourse.julialang.org/u/oheil)\
**Replies:** 67\
**Last updated:** [December 2, 2020, 3:51pm UTC](https://discourse.julialang.org/t/csv-reader-benchmarks-julia-reads-csvs-10-20x-faster-than-python-and-r/41974 "2020-12-02T15:51:24Z")

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This is huge! For non germans it is about recent performance boosts in Julia 1.4 and refers mainly to the following Blog CSV Reader Benchmarks: Julia Reads CSVs 10-20x Faster than Python and R - JuliaHub (blog url up…

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## [Data assignments between arrays of arrays](https://discourse.julialang.org/t/data-assignments-between-arrays-of-arrays/78326)

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**Author:** [@PrintRind](https://discourse.julialang.org/u/PrintRind)\
**Replies:** 3\
**Last updated:** [March 23, 2022, 12:58pm UTC](https://discourse.julialang.org/t/data-assignments-between-arrays-of-arrays/78326 "2022-03-23T12:58:56Z")

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As an old Matlab user I am still sometimes struggling to understand how Julia assigns data in “arrays of arrays”: For example, I want to copy a page of data from a 3D data array. The result is a Matrix, as expected: A …

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## [Help with understanding Mutating arrays error in a Flux model](https://discourse.julialang.org/t/help-with-understanding-mutating-arrays-error-in-a-flux-model/78295)

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**Author:** [@linkz](https://discourse.julialang.org/u/linkz)\
**Replies:** 3\
**Last updated:** [March 23, 2022, 11:17am UTC](https://discourse.julialang.org/t/help-with-understanding-mutating-arrays-error-in-a-flux-model/78295 "2022-03-23T11:17:59Z")

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I am trying to train a custom DiffEqFlux neural ODE model and wanting to use parts of the solution in a regularization term. I wrote the following brief function: function gen\_penalty(arr, similarity) …

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## [Fitting a binary model where the groups are on both sides](https://discourse.julialang.org/t/fitting-a-binary-model-where-the-groups-are-on-both-sides/78327)

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**Author:** [@rikh](https://discourse.julialang.org/u/rikh)\
**Replies:** 0\
**Last updated:** [March 23, 2022, 10:49am UTC](https://discourse.julialang.org/t/fitting-a-binary-model-where-the-groups-are-on-both-sides/78327 "2022-03-23T10:49:19Z")

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I’m trying to fit a model to predict graduation versus dropout, that is, a binary logistic regression. Theoretically and based on the data, I suspect that dropouts are more likely to be extremely slow or extremely quick,…

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## [Gradient of ldiv trace on CUDA](https://discourse.julialang.org/t/gradient-of-ldiv-trace-on-cuda/78283)

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**Author:** [@HenriDeh](https://discourse.julialang.org/u/HenriDeh)\
**Replies:** 3\
**Last updated:** [March 23, 2022, 10:19am UTC](https://discourse.julialang.org/t/gradient-of-ldiv-trace-on-cuda/78283 "2022-03-23T10:19:38Z")

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Hello, I’m trying to differentiate a left matrix division on CuArrays. I actually have the L parts l1,l2 of lu-decompositions of two matrices M1, M2 respectively. So m = l1\*l1' I made two functions, one that reconstruc…

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## [\[ANN\] LogarithmicNumbers.jl v1.0.0](https://discourse.julialang.org/t/ann-logarithmicnumbers-jl-v1-0-0/78305)

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**Author:** [@cjdoris](https://discourse.julialang.org/u/cjdoris)\
**Replies:** 3\
**Last updated:** [March 23, 2022, 10:08am UTC](https://discourse.julialang.org/t/ann-logarithmicnumbers-jl-v1-0-0/78305 "2022-03-23T10:08:50Z")

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LogarithmicNumbers.jl is a logarithmic number system for Julia. It provides signed Logarithmic{T} and unsigned ULogarithmic{T} real number types which store the logarithm of the number. This means you can represent real…

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## [Faster zeros with calloc](https://discourse.julialang.org/t/faster-zeros-with-calloc/69860)

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**Author:** [@mkitti](https://discourse.julialang.org/u/mkitti)\
**Replies:** 26\
**Last updated:** [March 23, 2022, 9:47am UTC](https://discourse.julialang.org/t/faster-zeros-with-calloc/69860 "2022-03-23T09:47:20Z")

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Abstract TL; DR zeros\_via\_calloc is a potentially faster version of zeros that is comparable to Array{T}(undef, ...) and numpy.zeros. function zeros\_via\_calloc(::Type{T}, dims::Integer...) where T ptr = Ptr{T}(Libc.c…

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## [Warning regarding imported packages (\`LinearAlgebra\` and \`DrWatson\`)](https://discourse.julialang.org/t/warning-regarding-imported-packages-linearalgebra-and-drwatson/78319)

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**Author:** [@ultrapoci](https://discourse.julialang.org/u/ultrapoci)\
**Replies:** 0\
**Last updated:** [March 23, 2022, 8:17am UTC](https://discourse.julialang.org/t/warning-regarding-imported-packages-linearalgebra-and-drwatson/78319 "2022-03-23T08:17:30Z")

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I’m using Julia 1.7.2 and I’m trying to set up a project to work on. I’ve created the folder using DrWatson and I’ve added Revise to startup.jl: the idea is of course to have to ability to modify code (I’m using VSCode b…

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## [Pluto Reactivity and eval](https://discourse.julialang.org/t/pluto-reactivity-and-eval/78250)

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**Author:** [@TI36XPro](https://discourse.julialang.org/u/TI36XPro)\
**Replies:** 3\
**Last updated:** [March 23, 2022, 8:01am UTC](https://discourse.julialang.org/t/pluto-reactivity-and-eval/78250 "2022-03-23T08:01:23Z")

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I recently discovered Latexify.jl and really like it. I am trying to combine it with Pluto but am failing. I’d appreciate any hints. I have a pluto notebook with a cell that contains the following. begin fex = :(f(x)=…

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## [Allocation depending on value of typed field in struct](https://discourse.julialang.org/t/allocation-depending-on-value-of-typed-field-in-struct/78317)

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**Author:** [@slocook](https://discourse.julialang.org/u/slocook)\
**Replies:** 4\
**Last updated:** [March 23, 2022, 6:39am UTC](https://discourse.julialang.org/t/allocation-depending-on-value-of-typed-field-in-struct/78317 "2022-03-23T06:39:07Z")

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I’m seeing some behavior with accessing data members of structs that I don’t understand - depending on the value of typed field in a struct, I’m getting an allocation with getfield. struct MyStruct v::Int end ms0 =…

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## [Genetic Algorithm with solutions over a discrete set of values](https://discourse.julialang.org/t/genetic-algorithm-with-solutions-over-a-discrete-set-of-values/78256)

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**Author:** [@Jack](https://discourse.julialang.org/u/Jack)\
**Replies:** 0\
**Last updated:** [March 22, 2022, 7:32am UTC](https://discourse.julialang.org/t/genetic-algorithm-with-solutions-over-a-discrete-set-of-values/78256 "2022-03-22T07:32:10Z")

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I checked out the genetic algorithm package Evolutionary.jl and find it doesn’t support that user specifying possible solutions over a discrete set of values, or solutions only take on integer values. I noticed that the g…

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## [Trouble with sequential LP solve (JuMP, HiGHS)](https://discourse.julialang.org/t/trouble-with-sequential-lp-solve-jump-highs/78203)

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**Author:** [@gleyland](https://discourse.julialang.org/u/gleyland)\
**Replies:** 4\
**Last updated:** [March 23, 2022, 5:29am UTC](https://discourse.julialang.org/t/trouble-with-sequential-lp-solve-jump-highs/78203 "2022-03-23T05:29:57Z")

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Hi, I’m afraid this is going to be completely unreproduceable, but after a couple of days I’m starting to think that my problem might not be entirely my own mistakes. I’m using JuMP and HiGHS (or Gurobi) to solve seque…

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## [Calling julia functions from python](https://discourse.julialang.org/t/calling-julia-functions-from-python/6885)

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**Author:** [@villageidiot](https://discourse.julialang.org/u/villageidiot)\
**Replies:** 17\
**Last updated:** [March 23, 2022, 4:49am UTC](https://discourse.julialang.org/t/calling-julia-functions-from-python/6885 "2022-03-23T04:49:42Z")

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I’m interested in using Julia to speed up parts of a python program I’m writing. It seems pyjulia GitHub - JuliaPy/pyjulia: python interface to julia is the standard package to do this with? As it uses pycall I guess it…

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## [Asof merge in Julia](https://discourse.julialang.org/t/asof-merge-in-julia/76948)

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**Author:** [@ameresv](https://discourse.julialang.org/u/ameresv)\
**Replies:** 12\
**Last updated:** [March 23, 2022, 4:38am UTC](https://discourse.julialang.org/t/asof-merge-in-julia/76948 "2022-03-23T04:38:48Z")

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Hi, I am trying to do an ‘as of’ merge in Julia with two large Dataframes, based on the time and the equipment\_id provided. As a manner of example, let me introduce the two df.head() using DataFrames df1 = DataFrame( …

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## [Rowwise compuation in \`InMemoryDatasets.jl\` vs \`DataFrames.jl\`](https://discourse.julialang.org/t/rowwise-compuation-in-inmemorydatasets-jl-vs-dataframes-jl/78314)

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**Author:** [@monopolynomial](https://discourse.julialang.org/u/monopolynomial)\
**Replies:** 2\
**Last updated:** [March 23, 2022, 4:31am UTC](https://discourse.julialang.org/t/rowwise-compuation-in-inmemorydatasets-jl-vs-dataframes-jl/78314 "2022-03-23T04:31:05Z")

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byrow function in InMemoryDatasets is fantastic :+1: , I have done a small benchmark to compare its performance against DataFrames.jl for relatively wide tables. argmax in DataFrames.jl takes long! InMemoryDatasets jul…

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## [How to run Stan diagnose binary using StanSample.jl](https://discourse.julialang.org/t/how-to-run-stan-diagnose-binary-using-stansample-jl/78304)

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**Author:** [@Stephen\_Wild](https://discourse.julialang.org/u/Stephen_Wild)\
**Replies:** 3\
**Last updated:** [March 22, 2022, 11:59pm UTC](https://discourse.julialang.org/t/how-to-run-stan-diagnose-binary-using-stansample-jl/78304 "2022-03-22T23:59:58Z")

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Hello, I am trying to run Stan’s diagnose binary on a model. Unfortunately, I am getting an error. Here is some reproducible code using the example bernoulli model. using StanSample, DataFrames ProjDir = @\_\_DIR\_\_ ber…

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## [Keyword behaves differently using \`;\` or \`,\`](https://discourse.julialang.org/t/keyword-behaves-differently-using-or/78233)

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**Author:** [@odow](https://discourse.julialang.org/u/odow)\
**Replies:** 13\
**Last updated:** [March 22, 2022, 9:17pm UTC](https://discourse.julialang.org/t/keyword-behaves-differently-using-or/78233 "2022-03-22T21:17:21Z")

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Is this intended? It had @ccoffrin and I quite confused (not the subtle difference between , and ;): julia\> sum(0.0 for i in \[\]; init = 0.0) 0.0 julia\> sum(0.0 for i in \[\], init = 0.0) ERROR: ArgumentError: reducing ov…

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## [Is there any other channel for package announcements?](https://discourse.julialang.org/t/is-there-any-other-channel-for-package-announcements/78261)

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**Author:** [@sl-solution](https://discourse.julialang.org/u/sl-solution)\
**Replies:** 2\
**Last updated:** [March 22, 2022, 11:42pm UTC](https://discourse.julialang.org/t/is-there-any-other-channel-for-package-announcements/78261 "2022-03-22T23:42:12Z")

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Hi every one, I just wondering if there is any other formal channel for announcing Julia packages?

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## [Lag/lead in panel data](https://discourse.julialang.org/t/lag-lead-in-panel-data/48140)

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**Author:** [@RangeFu](https://discourse.julialang.org/u/RangeFu)\
**Replies:** 18\
**Last updated:** [March 22, 2022, 11:34pm UTC](https://discourse.julialang.org/t/lag-lead-in-panel-data/48140 "2022-03-22T23:34:42Z")

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I just transitted from Stata/Pandas to DataFrames.jl. I was wondering what the best practice is to deal with panel data in Julia. One of the common manipulations for panel data is the lag/lead operator for each individu…

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## [FermiDiracIntegrals](https://discourse.julialang.org/t/fermidiracintegrals/78301)

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**Author:** [@feanor12](https://discourse.julialang.org/u/feanor12)\
**Replies:** 0\
**Last updated:** [March 22, 2022, 7:42pm UTC](https://discourse.julialang.org/t/fermidiracintegrals/78301 "2022-03-22T19:42:43Z")

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I registered a small package to calculate the complete Fermi-Dirac integral. This is useful when Fermi statistics is used, which appears for example in the bandstructures of doped semiconductors. There is also an appro…

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## [Updating registry takes half an hour](https://discourse.julialang.org/t/updating-registry-takes-half-an-hour/78300)

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**Author:** [@Gregstrq](https://discourse.julialang.org/u/Gregstrq)\
**Replies:** 6\
**Last updated:** [March 22, 2022, 8:33pm UTC](https://discourse.julialang.org/t/updating-registry-takes-half-an-hour/78300 "2022-03-22T20:33:11Z")

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I am running julia 1.6.2 on SMP Debian 4.9.189-3 with kernel version 4.9.0-11-amd64. Whenever I try to add a package, updating registry takes half an hour. I have tried to delete ~/.julia/registries folder, but the upda…

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## [Variable Length Optimization Algorithms?](https://discourse.julialang.org/t/variable-length-optimization-algorithms/78285)

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**Author:** [@ParadaCarleton](https://discourse.julialang.org/u/ParadaCarleton)\
**Replies:** 3\
**Last updated:** [March 22, 2022, 8:02pm UTC](https://discourse.julialang.org/t/variable-length-optimization-algorithms/78285 "2022-03-22T20:02:49Z")

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Are there any implementations of algorithms for variable-length optimization, where the number of parameters can vary? Examples can be found here (particle swarm based), here, here, and here (genetic algorithms). (If no…

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## [StructArrays (for Complex arrays) and DifferentialEquations not working together](https://discourse.julialang.org/t/structarrays-for-complex-arrays-and-differentialequations-not-working-together/78274)

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**Author:** [@Elyco](https://discourse.julialang.org/u/Elyco)\
**Replies:** 4\
**Last updated:** [March 22, 2022, 7:12pm UTC](https://discourse.julialang.org/t/structarrays-for-complex-arrays-and-differentialequations-not-working-together/78274 "2022-03-22T19:12:01Z")

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Hi everyone, I’m trying to solve some differential equations. But I can’t make it works together with StructArrays.jl :frowning: From the stacktrace I understand that when the differential equation package tries to se…

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