# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1706

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

**Page:** 1707

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## [Deterministic Clustering in Julia?](https://discourse.julialang.org/t/deterministic-clustering-in-julia/42068)

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**Author:** [@mthelm85](https://discourse.julialang.org/u/mthelm85)\
**Replies:** 4\
**Last updated:** [June 26, 2020, 6:54am UTC](https://discourse.julialang.org/t/deterministic-clustering-in-julia/42068 "2020-06-26T06:54:41Z")

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Are there any deterministic clustering methods implemented in Julia? For example: using Clustering using DataFrames df = DataFrame(subject=1:10, height=rand(10), weight=rand(10)) julia\> groups = kmeans(Matrix(df\[:, 2:…

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## [Why doesn't this view assignment work?](https://discourse.julialang.org/t/why-doesnt-this-view-assignment-work/42030)

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**Author:** [@jiggunjer](https://discourse.julialang.org/u/jiggunjer)\
**Replies:** 8\
**Last updated:** [June 26, 2020, 6:51am UTC](https://discourse.julialang.org/t/why-doesnt-this-view-assignment-work/42030 "2020-06-26T06:51:07Z")

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Hello. I am using the Images package to do some processing. I have an RGB image img, and I’d like to create a view such that I can index channels by name. My idea was to derive view slices from the channelView: cv = cha…

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## [Adaptive control and online parameter estimation](https://discourse.julialang.org/t/adaptive-control-and-online-parameter-estimation/42054)

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**Author:** [@jonniedie](https://discourse.julialang.org/u/jonniedie)\
**Replies:** 2\
**Last updated:** [June 26, 2020, 2:01am UTC](https://discourse.julialang.org/t/adaptive-control-and-online-parameter-estimation/42054 "2020-06-26T02:01:27Z")

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Since control systems modeling questions tend to pop up on here quite a bit, I figured I’d share the approach I’ve been taking for these kinds of things using ControlSystems.jl to build linear components for nonlinear Di…

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## [Improve CBC solve time](https://discourse.julialang.org/t/improve-cbc-solve-time/42082)

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**Author:** [@GeneralPoxter](https://discourse.julialang.org/u/GeneralPoxter)\
**Replies:** 2\
**Last updated:** [June 26, 2020, 3:00am UTC](https://discourse.julialang.org/t/improve-cbc-solve-time/42082 "2020-06-26T03:00:20Z")

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While watching the output of the CBC optimizer, I noticed that after a while, the optimizer would get “stuck” on a best solution, even though I set the primal tolerance and allowable gap to relatively low values. I also…

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## [Poor performance of \`lock(l) do\` closures, caused by poor performance of capturing closures](https://discourse.julialang.org/t/poor-performance-of-lock-l-do-closures-caused-by-poor-performance-of-capturing-closures/42067)

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**Author:** [@NHDaly](https://discourse.julialang.org/u/NHDaly)\
**Replies:** 11\
**Last updated:** [June 26, 2020, 2:45am UTC](https://discourse.julialang.org/t/poor-performance-of-lock-l-do-closures-caused-by-poor-performance-of-capturing-closures/42067 "2020-06-26T02:45:38Z")

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Multithreading is hard. Correctly and safely locking and unlocking can be hard. For these reasons, we prefer abstractions that help us do things safely and correctly. One such abstraction is the lock() method that take…

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## [Function with multiple arguments with all subsets of variables](https://discourse.julialang.org/t/function-with-multiple-arguments-with-all-subsets-of-variables/42022)

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**Author:** [@sergevic](https://discourse.julialang.org/u/sergevic)\
**Replies:** 7\
**Last updated:** [June 26, 2020, 2:08am UTC](https://discourse.julialang.org/t/function-with-multiple-arguments-with-all-subsets-of-variables/42022 "2020-06-26T02:08:31Z")

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I have to construct a set of functions that I want to optimize. The set consists of functions with all subsets I can build with p variables. If p is small, that’s easy. For example, with p=2, I can build 2^2-1=3 function…

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## [C types interchangeability with Julia types](https://discourse.julialang.org/t/c-types-interchangeability-with-julia-types/42083)

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**Author:** [@pauljurczak](https://discourse.julialang.org/u/pauljurczak)\
**Replies:** 0\
**Last updated:** [June 26, 2020, 12:26am UTC](https://discourse.julialang.org/t/c-types-interchangeability-with-julia-types/42083 "2020-06-26T00:26:02Z")

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I wrote a wrapper of C library. Here is one of C functions: extern "C" bool start(char\* nodeName) and Julia equivalent: export start function start(nodeName::String) ccall((:start, "libsimc.so"), Bool, (Cstring,), …

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## [Worker on cluster : Package not found in current path](https://discourse.julialang.org/t/worker-on-cluster-package-not-found-in-current-path/40887)

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**Author:** [@amitjamadagni](https://discourse.julialang.org/u/amitjamadagni)\
**Replies:** 3\
**Last updated:** [June 25, 2020, 11:16pm UTC](https://discourse.julialang.org/t/worker-on-cluster-package-not-found-in-current-path/40887 "2020-06-25T23:16:15Z")

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Hello, I have been trying to get some packages to run on a cluster. I have set the variable JULIA\_DEPOT\_PATH to a custom folder where I have installed the required packages and my job script looks as follows: #========…

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## [Luxor questions](https://discourse.julialang.org/t/luxor-questions/41946)

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**Author:** [@turtle](https://discourse.julialang.org/u/turtle)\
**Replies:** 14\
**Last updated:** [June 25, 2020, 11:00pm UTC](https://discourse.julialang.org/t/luxor-questions/41946 "2020-06-25T23:00:11Z")

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I have started learning Luxor.jl, and I find it great. I would have two questions: Can I reverse the default coordinate system somehow? (i.e. x axis to the right, but y axis upwards) Can I use LaTeX expressions as te…

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## [Images - Kernel sizes and ImageAxes](https://discourse.julialang.org/t/images-kernel-sizes-and-imageaxes/41858)

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**Author:** [@mirestrepo](https://discourse.julialang.org/u/mirestrepo)\
**Replies:** 3\
**Last updated:** [June 25, 2020, 9:53pm UTC](https://discourse.julialang.org/t/images-kernel-sizes-and-imageaxes/41858 "2020-06-25T21:53:46Z")

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Hi All, This is probably a naive question. Given an image stack with z-spacing that is not the same as x and y, what is the correct way to handle the size for example of the σshape for the laplacian of gaussian? I hav…

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## [Normalized laplacian of weighted graphs](https://discourse.julialang.org/t/normalized-laplacian-of-weighted-graphs/42064)

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**Author:** [@Neurovium](https://discourse.julialang.org/u/Neurovium)\
**Replies:** 1\
**Last updated:** [June 25, 2020, 8:55pm UTC](https://discourse.julialang.org/t/normalized-laplacian-of-weighted-graphs/42064 "2020-06-25T20:55:26Z")

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Hi, Is there anyway to calculate normalized laplacian for a weighted graph? See below for an example graph created with SimpleWeightedGraphs (https://github.com/JuliaGraphs/SimpleWeightedGraphs.jl) When I call Normal…

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## [What is the fastest way to update a particular row of a matrix using dot syntax?](https://discourse.julialang.org/t/what-is-the-fastest-way-to-update-a-particular-row-of-a-matrix-using-dot-syntax/36160)

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**Author:** [@tomohiro\_soejima](https://discourse.julialang.org/u/tomohiro_soejima)\
**Replies:** 21\
**Last updated:** [June 25, 2020, 7:58pm UTC](https://discourse.julialang.org/t/what-is-the-fastest-way-to-update-a-particular-row-of-a-matrix-using-dot-syntax/36160 "2020-06-25T19:58:17Z")

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Hi, I have a square matrix M, and I would like to update it in-place such that the kth column is multiplied by some scalar s. I’ve tried implementing it with dot syntax and simple rolling out of the for loop. function …

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## [Repartitioning 2TB of csv into parquets](https://discourse.julialang.org/t/repartitioning-2tb-of-csv-into-parquets/27716)

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**Author:** [@gabomgp](https://discourse.julialang.org/u/gabomgp)\
**Replies:** 21\
**Last updated:** [June 25, 2020, 6:09pm UTC](https://discourse.julialang.org/t/repartitioning-2tb-of-csv-into-parquets/27716 "2020-06-25T18:09:31Z")

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Good morning from Colombia. I’m beginner in big data/data science, and i’m trying to do the next task: We have 2 TB of CSV from one table. We want to try to use a SQL Layer to query that data. Currently, the data is s…

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## [Request: I can't understand why a result of matrix multiplication in Julia like this](https://discourse.julialang.org/t/request-i-cant-understand-why-a-result-of-matrix-multiplication-in-julia-like-this/42050)

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**Author:** [@Hyeonji-Ryu](https://discourse.julialang.org/u/Hyeonji-Ryu)\
**Replies:** 2\
**Last updated:** [June 25, 2020, 4:39pm UTC](https://discourse.julialang.org/t/request-i-cant-understand-why-a-result-of-matrix-multiplication-in-julia-like-this/42050 "2020-06-25T16:39:23Z")

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Hello, I’m a student using Julia in my project making deep learning model. I usually use ‘matrix multiplication’ a lot in my code. then, I found some result is weird. I think it’s better to show some examples than to …

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## [Parallel computing using Optim](https://discourse.julialang.org/t/parallel-computing-using-optim/41948)

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**Author:** [@Joris\_Pinkse](https://discourse.julialang.org/u/Joris_Pinkse)\
**Replies:** 5\
**Last updated:** [June 25, 2020, 3:55pm UTC](https://discourse.julialang.org/t/parallel-computing-using-optim/41948 "2020-06-25T15:55:49Z")

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Hello, I’m running the program below on a 32 cpu/64 thread system without much of anything else running on it. If I use anything beyond 16 cores then the execution time in the second run is effectively flat. This is t…

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## [How to reduce bar padding in horizontal bar plotting?](https://discourse.julialang.org/t/how-to-reduce-bar-padding-in-horizontal-bar-plotting/42039)

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**Author:** [@sylvaticus](https://discourse.julialang.org/u/sylvaticus)\
**Replies:** 2\
**Last updated:** [June 25, 2020, 3:40pm UTC](https://discourse.julialang.org/t/how-to-reduce-bar-padding-in-horizontal-bar-plotting/42039 "2020-06-25T15:40:22Z")

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How can I set the bar padding in bar ? using Plots kDiff = \[-0.4665307712613753, 1.3988034802362372, 0.26964352271121106, 1.9321483556515853, 0.027055373158908935, -0.2508916681408131\] sentences = \["Industrie", "Noeffec…

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## [Mathematical symbols in Julia](https://discourse.julialang.org/t/mathematical-symbols-in-julia/41960)

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**Author:** [@Chris\_Anderson](https://discourse.julialang.org/u/Chris_Anderson)\
**Replies:** 12\
**Last updated:** [June 25, 2020, 5:06am UTC](https://discourse.julialang.org/t/mathematical-symbols-in-julia/41960 "2020-06-25T05:06:28Z")

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I’m not sure if this is the right place for this, so I apologize if it’s misplaced. I was wondering if there was something in Julia equivalent to LaTeX. I study mathematics and so could use something like LaTeX, but if…

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## [\`rand() + I\` vs \`rand() .+ I\`](https://discourse.julialang.org/t/rand-i-vs-rand-i/41985)

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**Author:** [@v-i-s-h](https://discourse.julialang.org/u/v-i-s-h)\
**Replies:** 7\
**Last updated:** [June 25, 2020, 3:15pm UTC](https://discourse.julialang.org/t/rand-i-vs-rand-i/41985 "2020-06-25T15:15:02Z")

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What is the difference between rand() + I and rand() .+ I? (I is from using LinearAlgebra). The first one works, but second on throws error. julia\> rand() + I 1.04893935660533 julia\> rand() .+ I ERROR: MethodError: no…

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## [FreeBSD GR download link missing](https://discourse.julialang.org/t/freebsd-gr-download-link-missing/24241)

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**Author:** [@Rob\_van\_Weelderen](https://discourse.julialang.org/u/Rob_van_Weelderen)\
**Replies:** 2\
**Last updated:** [June 25, 2020, 2:10pm UTC](https://discourse.julialang.org/t/freebsd-gr-download-link-missing/24241 "2020-06-25T14:10:41Z")

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Hi there, I’m trying to install the GR plotting library on FreeBSD 12.0 (stable), but the build fails with the message (see below), of which the main complaint is: Error opening archive: Failed to open 'downloads/gr-0.…

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## [Plotting the evolution of the optimization using Optim.jl](https://discourse.julialang.org/t/plotting-the-evolution-of-the-optimization-using-optim-jl/41978)

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**Author:** [@cmey](https://discourse.julialang.org/u/cmey)\
**Replies:** 3\
**Last updated:** [June 25, 2020, 1:52pm UTC](https://discourse.julialang.org/t/plotting-the-evolution-of-the-optimization-using-optim-jl/41978 "2020-06-25T13:52:19Z")

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Hi! What’s a good strategy to plot the evolution of the solution x during the optimization using Optim.jl? Note: I’m looking for the value of the solution, not the value of the objective function nor the value of the gr…

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## [Help eliminating allocations](https://discourse.julialang.org/t/help-eliminating-allocations/42019)

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**Author:** [@Ronis\_BR](https://discourse.julialang.org/u/Ronis_BR)\
**Replies:** 6\
**Last updated:** [June 25, 2020, 1:51pm UTC](https://discourse.julialang.org/t/help-eliminating-allocations/42019 "2020-06-25T13:51:22Z")

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Hi! I need to reproduce a code in a Kernel include file. In a part, it computes the size of an array of chars. Initially, I was doing something like this, which perfectly mimics the behavior in the .h: function test(a:…

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## [\[ANN\] BaremetalPi.jl 0.1.1](https://discourse.julialang.org/t/ann-baremetalpi-jl-0-1-1/42007)

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**Author:** [@Ronis\_BR](https://discourse.julialang.org/u/Ronis_BR)\
**Replies:** 2\
**Last updated:** [June 25, 2020, 1:32pm UTC](https://discourse.julialang.org/t/ann-baremetalpi-jl-0-1-1/42007 "2020-06-25T13:32:15Z")

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Hi! Just a small announcement. I just release the version 0.1.1 of BaremetalPi.jl. It should be available in the next few hours. The greatest change is that I manage to provide functions to transfer information using S…

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## [A question about sort](https://discourse.julialang.org/t/a-question-about-sort/42035)

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**Author:** [@abcde](https://discourse.julialang.org/u/abcde)\
**Replies:** 4\
**Last updated:** [June 25, 2020, 1:24pm UTC](https://discourse.julialang.org/t/a-question-about-sort/42035 "2020-06-25T13:24:20Z")

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How do I sort by the imaginary part of a complex matrix?what function? thanks!

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## [Parrallel programming2](https://discourse.julialang.org/t/parrallel-programming2/42027)

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**Author:** [@hyacykcharel](https://discourse.julialang.org/u/hyacykcharel)\
**Replies:** 3\
**Last updated:** [June 25, 2020, 10:46am UTC](https://discourse.julialang.org/t/parrallel-programming2/42027 "2020-06-25T10:46:40Z")

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Hello im trying to run this for loop parallel on evwery Process but still getting Error ,I Triyed it in 2 ways, can someone Help please?thanks using Distributed addprocs(2) @everywhere using DistributedArrays @every…

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## [Any way to speed up sorting a dataframe? A more efficient sortperm would be great](https://discourse.julialang.org/t/any-way-to-speed-up-sorting-a-dataframe-a-more-efficient-sortperm-would-be-great/41995)

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**Author:** [@xiaodai](https://discourse.julialang.org/u/xiaodai)\
**Replies:** 2\
**Last updated:** [June 25, 2020, 9:55am UTC](https://discourse.julialang.org/t/any-way-to-speed-up-sorting-a-dataframe-a-more-efficient-sortperm-would-be-great/41995 "2020-06-25T09:55:46Z")

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Consideirng a DataFrame using DataFrames using Random: randstring M = 100\_000\_000 str\_base = \[randstring(8) for i in 1:1\_000\_000\] df = DataFrame(int = rand(Int32, M), float=rand(M), str = rand(str\_base, M)) @time sort!…

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## [Constructors for \`UnionAll\` types](https://discourse.julialang.org/t/constructors-for-unionall-types/41999)

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**Author:** [@mhauru](https://discourse.julialang.org/u/mhauru)\
**Replies:** 2\
**Last updated:** [June 25, 2020, 9:44am UTC](https://discourse.julialang.org/t/constructors-for-unionall-types/41999 "2020-06-25T09:44:14Z")

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I have a simple type with two parameters, something like julia\> struct Thingy{N, T} a::NTuple{N, T} end and I try to define the following constructors for it, where the second parameter is fixed: jul…

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## [What are some good ways to compute terms in recurrence relations?](https://discourse.julialang.org/t/what-are-some-good-ways-to-compute-terms-in-recurrence-relations/42016)

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**Author:** [@xiaodai](https://discourse.julialang.org/u/xiaodai)\
**Replies:** 9\
**Last updated:** [June 25, 2020, 8:57am UTC](https://discourse.julialang.org/t/what-are-some-good-ways-to-compute-terms-in-recurrence-relations/42016 "2020-06-25T08:57:04Z")

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Doing a google search on “recurrence relations Julia” shows up MathToolkit.jl which has not been updated for a while and it’s got a neat function for detecting recurrence relations but not for solving them given the coef…

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## [Is there a turing alternative to pm.Deterministic from pymc3?](https://discourse.julialang.org/t/is-there-a-turing-alternative-to-pm-deterministic-from-pymc3/38667)

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**Author:** [@3210jr](https://discourse.julialang.org/u/3210jr)\
**Replies:** 4\
**Last updated:** [June 25, 2020, 8:41am UTC](https://discourse.julialang.org/t/is-there-a-turing-alternative-to-pm-deterministic-from-pymc3/38667 "2020-06-25T08:41:51Z")

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Hey all, I am looking an alternative to pm.Deterministic so that I can store and return a computed value. Thanks

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## [A question about fft function](https://discourse.julialang.org/t/a-question-about-fft-function/42026)

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**Author:** [@abcde](https://discourse.julialang.org/u/abcde)\
**Replies:** 1\
**Last updated:** [June 25, 2020, 7:24am UTC](https://discourse.julialang.org/t/a-question-about-fft-function/42026 "2020-06-25T07:24:25Z")

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it does not work ,why? a=\[1 ,2 ,3 ,4\] b=\[7 8 9 5\] foo=x-\>fft(x,2) foo.(b) #print(fft(b,2))

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## [Speeding up repeated optimizations within a large loop](https://discourse.julialang.org/t/speeding-up-repeated-optimizations-within-a-large-loop/41901)

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**Author:** [@asyadav](https://discourse.julialang.org/u/asyadav)\
**Replies:** 7\
**Last updated:** [June 25, 2020, 7:22am UTC](https://discourse.julialang.org/t/speeding-up-repeated-optimizations-within-a-large-loop/41901 "2020-06-25T07:22:59Z")

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Hi there! I’m trying to solve an economic model with many discrete and continuous choices and a fairly large state space. My approach essentially boils down to solving several constrained optimization problems, using Opt…

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