# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1755

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

**Page:** 1756

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## [Is there a summary of what changed from CategoricalArrays.jl v0.7-0.8?](https://discourse.julialang.org/t/is-there-a-summary-of-what-changed-from-categoricalarrays-jl-v0-7-0-8/38875)

<div class="topic-metadata">

**Author:** [@xiaodai](https://discourse.julialang.org/u/xiaodai)\
**Replies:** 0\
**Last updated:** [May 6, 2020, 10:07am UTC](https://discourse.julialang.org/t/is-there-a-summary-of-what-changed-from-categoricalarrays-jl-v0-7-0-8/38875 "2020-05-06T10:07:20Z")

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I can’t seem to find a list of changes for the breaking change from CategoricalArray.jl 0.7 to 0.8. Does anyone have a list?

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## [Turing model runs with one sampler but not with another](https://discourse.julialang.org/t/turing-model-runs-with-one-sampler-but-not-with-another/38872)

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**Author:** [@Manoj\_Gopalkrishnan](https://discourse.julialang.org/u/Manoj_Gopalkrishnan)\
**Replies:** 2\
**Last updated:** [May 6, 2020, 10:04am UTC](https://discourse.julialang.org/t/turing-model-runs-with-one-sampler-but-not-with-another/38872 "2020-05-06T10:04:03Z")

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I try the following code and it gives an error @model tr(l) = begin m = length(l) x = Array{Union{Float64,Missing},1}(missing,m) for i =1:m x\[i\] ~ Normal(0,i) end return x end m = tr(\[1,2,3\]…

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## [Math operation known issue? a^b](https://discourse.julialang.org/t/math-operation-known-issue-a-b/38839)

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**Author:** [@Rougem](https://discourse.julialang.org/u/Rougem)\
**Replies:** 11\
**Last updated:** [May 6, 2020, 9:17am UTC](https://discourse.julialang.org/t/math-operation-known-issue-a-b/38839 "2020-05-06T09:17:20Z")

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Today is my first day with Julia. While, working with the command line I realized that some results were negative and wrong. I am new, so if I made a mistake please let me know. What is wrong? Thanks a lot! Issue:

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## [Collect an iterator into an SVector or Tuple](https://discourse.julialang.org/t/collect-an-iterator-into-an-svector-or-tuple/38812)

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**Author:** [@Tamas\_Papp](https://discourse.julialang.org/u/Tamas_Papp)\
**Replies:** 6\
**Last updated:** [May 6, 2020, 8:41am UTC](https://discourse.julialang.org/t/collect-an-iterator-into-an-svector-or-tuple/38812 "2020-05-06T08:41:42Z")

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Is there a recommended idiom for collecting a number of elements (known at compile time, embedded in some type parameter) from an iterable into a Tuple or SVector? I can write a generated function and unroll, but I was …

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## [Two juno sessions on same machine?](https://discourse.julialang.org/t/two-juno-sessions-on-same-machine/38447)

<div class="topic-metadata">

**Author:** [@jaynick](https://discourse.julialang.org/u/jaynick)\
**Replies:** 4\
**Last updated:** [May 6, 2020, 8:05am UTC](https://discourse.julialang.org/t/two-juno-sessions-on-same-machine/38447 "2020-05-06T08:05:34Z")

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Helo After coding I run the program from Juno. It runs for a long time. While the first program is running, I would like to interactively edit a different program. To do this, does it work to open 2 atom editors on th…

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## [Initializing every element of an array with a different distribution](https://discourse.julialang.org/t/initializing-every-element-of-an-array-with-a-different-distribution/38862)

<div class="topic-metadata">

**Author:** [@Manoj\_Gopalkrishnan](https://discourse.julialang.org/u/Manoj_Gopalkrishnan)\
**Replies:** 1\
**Last updated:** [May 6, 2020, 7:33am UTC](https://discourse.julialang.org/t/initializing-every-element-of-an-array-with-a-different-distribution/38862 "2020-05-06T07:33:03Z")

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Hello, I have a Turing model which takes an array of unknown dimensions, and I want every element of that array to take on a different distribution based on the index. However, I’m having trouble making this work. Here’s…

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## [Create a new DataFrame Column that is of Type Array{Int64,2}](https://discourse.julialang.org/t/create-a-new-dataframe-column-that-is-of-type-array-int64-2/38850)

<div class="topic-metadata">

**Author:** [@Phillip\_Sutton](https://discourse.julialang.org/u/Phillip_Sutton)\
**Replies:** 2\
**Last updated:** [May 6, 2020, 7:05am UTC](https://discourse.julialang.org/t/create-a-new-dataframe-column-that-is-of-type-array-int64-2/38850 "2020-05-06T07:05:05Z")

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I need to track an Array{Int64.2} for each row in my data frame. The dimensions of the array are not standard across the rows. How do I instantiate that column before running through and filling it in later in my code?

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## [Trying to read parquet file that is using Zstd codec](https://discourse.julialang.org/t/trying-to-read-parquet-file-that-is-using-zstd-codec/32657)

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**Author:** [@ldsands](https://discourse.julialang.org/u/ldsands)\
**Replies:** 6\
**Last updated:** [May 6, 2020, 5:45am UTC](https://discourse.julialang.org/t/trying-to-read-parquet-file-that-is-using-zstd-codec/32657 "2020-05-06T05:45:26Z")

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Hello everyone, I would like to read a parquet file into a Julia DataFrame. Unfortunately for my Julia skills (but fortunately for my hard drive) the codec used to compress the parquet file was zstd. I have played aroun…

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## [Solver hang when using certain combination of callbacks in DiffEq](https://discourse.julialang.org/t/solver-hang-when-using-certain-combination-of-callbacks-in-diffeq/38846)

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**Author:** [@klaff](https://discourse.julialang.org/u/klaff)\
**Replies:** 3\
**Last updated:** [May 6, 2020, 5:30am UTC](https://discourse.julialang.org/t/solver-hang-when-using-certain-combination-of-callbacks-in-diffeq/38846 "2020-05-06T05:30:07Z")

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Hi, I’m trying to use a PeriodicCallback and two ContinuousCallbacks and I’m running into an issue. Here’s the MWE: using DifferentialEquations function usode!(du,u,p,t) C1 = 1.63e-9 RS = 790.0 C2 = 3.3e-…

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## [How to debug memory issues (when using DifferentialEquations)](https://discourse.julialang.org/t/how-to-debug-memory-issues-when-using-differentialequations/38775)

<div class="topic-metadata">

**Author:** [@klaff](https://discourse.julialang.org/u/klaff)\
**Replies:** 14\
**Last updated:** [May 6, 2020, 5:13am UTC](https://discourse.julialang.org/t/how-to-debug-memory-issues-when-using-differentialequations/38775 "2020-05-06T05:13:30Z")

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I’m trying to understand an apparent memory issue regarding a simulation I’m doing. Here’s a simplified version of what I’m running: using DifferentialEquations, Plots function usode!(du,u,p,t) C1 = 1.63e-9 R…

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## [Mutable struct versus Base.RefValue](https://discourse.julialang.org/t/mutable-struct-versus-base-refvalue/38743)

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**Author:** [@jbrea](https://discourse.julialang.org/u/jbrea)\
**Replies:** 3\
**Last updated:** [May 6, 2020, 4:49am UTC](https://discourse.julialang.org/t/mutable-struct-versus-base-refvalue/38743 "2020-05-06T04:49:11Z")

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For structures that contain among other things a mutable scalar, I see (at least) two approaches: Make the structure mutable mutable struct S1 vector1::Vector{Float64} vector2::Vector{Float64} matrix::Matr…

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## [\`varinfo()\` on a large SimpleGraph or DataFrame is prohibitively slow](https://discourse.julialang.org/t/varinfo-on-a-large-simplegraph-or-dataframe-is-prohibitively-slow/38851)

<div class="topic-metadata">

**Author:** [@CameronBieganek](https://discourse.julialang.org/u/CameronBieganek)\
**Replies:** 0\
**Last updated:** [May 6, 2020, 12:53am UTC](https://discourse.julialang.org/t/varinfo-on-a-large-simplegraph-or-dataframe-is-prohibitively-slow/38851 "2020-05-06T00:53:53Z")

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The only time I use varinfo is when I have a large object in memory and I want to know how much space it is taking. Unfortunately, in many scenarios varinfo runtime goes through the roof for large objects, so it’s imposs…

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## [Help to remove type instability when using getproperty](https://discourse.julialang.org/t/help-to-remove-type-instability-when-using-getproperty/38849)

<div class="topic-metadata">

**Author:** [@Ronis\_BR](https://discourse.julialang.org/u/Ronis_BR)\
**Replies:** 6\
**Last updated:** [May 6, 2020, 12:33am UTC](https://discourse.julialang.org/t/help-to-remove-type-instability-when-using-getproperty/38849 "2020-05-06T00:33:39Z")

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Hi! I have this structure: struct Workspace{T} x::Vector{T} s\_i::Vector{T} s\_b::Vector{T} end I would like to overload getproperty and getindex so that s.JD is x\[1\] and s.w is view(x,2:4). Following the sa…

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## [Subtype of template parameter](https://discourse.julialang.org/t/subtype-of-template-parameter/38830)

<div class="topic-metadata">

**Author:** [@atteson](https://discourse.julialang.org/u/atteson)\
**Replies:** 4\
**Last updated:** [May 5, 2020, 11:47pm UTC](https://discourse.julialang.org/t/subtype-of-template-parameter/38830 "2020-05-05T23:47:37Z")

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Is there a way to implement something like the following: abstract type T1{T} \<: T end I’m creating a type which sometimes acts like a Real (and I want to use it in packages that require Real) and sometimes acts like \<:…

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## [Setting up a cluster on Amazon AWS/Azure](https://discourse.julialang.org/t/setting-up-a-cluster-on-amazon-aws-azure/38624)

<div class="topic-metadata">

**Author:** [@affans](https://discourse.julialang.org/u/affans)\
**Replies:** 4\
**Last updated:** [May 5, 2020, 11:45pm UTC](https://discourse.julialang.org/t/setting-up-a-cluster-on-amazon-aws-azure/38624 "2020-05-05T23:45:09Z")

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Our university cluster is down and I have some time sensitive simulations I have to run. I looked into AWS and Azure, but never have really dealt with cloud computing… I need about 500 processors (simulation time is actu…

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## [Failed to create file when running make on Cygwin64](https://discourse.julialang.org/t/failed-to-create-file-when-running-make-on-cygwin64/38802)

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**Author:** [@Chen](https://discourse.julialang.org/u/Chen)\
**Replies:** 1\
**Last updated:** [May 5, 2020, 11:38pm UTC](https://discourse.julialang.org/t/failed-to-create-file-when-running-make-on-cygwin64/38802 "2020-05-05T23:38:59Z")

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System: Cygwin64 under Windows 10 I cloned the git repository: git clone https://github.com/JuliaLang/julia.git Then I ran make: \`cd julia make\` I got the following error message: \` % Total % Received % Xferd Aver…

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## [How to nest splicing contexts (i.e. @eval inside quote block)](https://discourse.julialang.org/t/how-to-nest-splicing-contexts-i-e-eval-inside-quote-block/38752)

<div class="topic-metadata">

**Author:** [@zachmatson](https://discourse.julialang.org/u/zachmatson)\
**Replies:** 5\
**Last updated:** [May 5, 2020, 10:33pm UTC](https://discourse.julialang.org/t/how-to-nest-splicing-contexts-i-e-eval-inside-quote-block/38752 "2020-05-05T22:33:59Z")

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I am trying to make a macro that needs to evaluate an arbitrary (not known at parse time) amount of iterations of some code, which will change each time. I am trying to figure out how you would separately splice into the…

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## [\`select not defined\` error whilst trying to plot a results DataFrame](https://discourse.julialang.org/t/select-not-defined-error-whilst-trying-to-plot-a-results-dataframe/38836)

<div class="topic-metadata">

**Author:** [@HarrisonWilde](https://discourse.julialang.org/u/HarrisonWilde)\
**Replies:** 0\
**Last updated:** [May 5, 2020, 9:36pm UTC](https://discourse.julialang.org/t/select-not-defined-error-whilst-trying-to-plot-a-results-dataframe/38836 "2020-05-05T21:36:27Z")

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Hi, I wrote some code to plot the results of some experiments the other day, and it worked fine, then I must have changed something because I am now getting a rather strange error: ERROR: UndefVarError: select not defin…

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## [JuAFEM shape gradient as a matrix](https://discourse.julialang.org/t/juafem-shape-gradient-as-a-matrix/38825)

<div class="topic-metadata">

**Author:** [@FrootLoops](https://discourse.julialang.org/u/FrootLoops)\
**Replies:** 4\
**Last updated:** [May 5, 2020, 8:49pm UTC](https://discourse.julialang.org/t/juafem-shape-gradient-as-a-matrix/38825 "2020-05-05T20:49:25Z")

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Hello everybody, I hope I am asking the question in a correct way. I am working with JuAFEM and I have a example code given, which calculates the stiffness matrix elementwise. @inbounds for q\_point in 1:getnquadpoints(…

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## [Non standard Hamiltonian dynamics - need high accuracy](https://discourse.julialang.org/t/non-standard-hamiltonian-dynamics-need-high-accuracy/38811)

<div class="topic-metadata">

**Author:** [@roi.holtzman](https://discourse.julialang.org/u/roi.holtzman)\
**Replies:** 10\
**Last updated:** [May 5, 2020, 8:41pm UTC](https://discourse.julialang.org/t/non-standard-hamiltonian-dynamics-need-high-accuracy/38811 "2020-05-05T20:41:22Z")

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I am solving dynamical ODEs that describe a Hamiltonian dynamics. However, I have that \\dot{p}=f\_1(q,p,t), \\dot{q} = f\_2(q,p,t), which does not apply to the requirements of the symplectic solvers available (or maybe am I…

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## [Distributions.jl structure](https://discourse.julialang.org/t/distributions-jl-structure/38214)

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**Author:** [@Albert\_Zevelev](https://discourse.julialang.org/u/Albert_Zevelev)\
**Replies:** 5\
**Last updated:** [May 5, 2020, 8:38pm UTC](https://discourse.julialang.org/t/distributions-jl-structure/38214 "2020-05-05T20:38:38Z")

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How can I automatically find all univariate continuous cdfs in Distributions.jl? I believe this can make a lot of tasks much easier including maintaining Distributions.jl. Eg MLJ.jl: using MLJ; X, y = @load\_boston; …

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## [Complex root finder for a general function f(z)?](https://discourse.julialang.org/t/complex-root-finder-for-a-general-function-f-z/35989)

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**Author:** [@hongchengni](https://discourse.julialang.org/u/hongchengni)\
**Replies:** 40\
**Last updated:** [May 5, 2020, 6:36pm UTC](https://discourse.julialang.org/t/complex-root-finder-for-a-general-function-f-z/35989 "2020-05-05T18:36:53Z")

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Hello, I am new to Julia. I wonder if there is a Julia package that can obtain the complex root for a general complex equation f(z)=0? I am aware there are packages such as Polynomials and PolynomialRoots, but they can o…

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## [Could you explain what are views?](https://discourse.julialang.org/t/could-you-explain-what-are-views/17535)

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**Author:** [@Juan](https://discourse.julialang.org/u/Juan)\
**Replies:** 2\
**Last updated:** [November 15, 2018, 12:15am UTC](https://discourse.julialang.org/t/could-you-explain-what-are-views/17535 "2018-11-15T00:15:57Z")

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Hello. Could you explain to a new user what are @view, @views, and other alternatives, please? What is something equivalent on base R or data.table? For example if I do: A = \[1 2; 3 4\] A\[:,:\] I get: 2×2 Array{I…

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## [Conditional sampling in Turing](https://discourse.julialang.org/t/conditional-sampling-in-turing/38783)

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**Author:** [@Manoj\_Gopalkrishnan](https://discourse.julialang.org/u/Manoj_Gopalkrishnan)\
**Replies:** 7\
**Last updated:** [May 5, 2020, 6:09pm UTC](https://discourse.julialang.org/t/conditional-sampling-in-turing/38783 "2020-05-05T18:09:44Z")

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Hello all, Newbie to Turing here. I want to introduce two random variables within a Turing model, say x ~ Bernoulli(.1) and y ~ Bernoulli(.5) or x,y are Normal distributions. I want to condition on the observation that…

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## [Copy of missing](https://discourse.julialang.org/t/copy-of-missing/38814)

<div class="topic-metadata">

**Author:** [@maarten\_van\_damme](https://discourse.julialang.org/u/maarten_van_damme)\
**Replies:** 2\
**Last updated:** [May 5, 2020, 4:15pm UTC](https://discourse.julialang.org/t/copy-of-missing/38814 "2020-05-05T16:15:33Z")

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should copy(missing) be defined as missing? I have an array of objects that are either there or missing. I’d like to write copy.(data), but copy(missing) is undefined. Is there a simple reason why this is not defined

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## [Error: variable inside a loop](https://discourse.julialang.org/t/error-variable-inside-a-loop/21504)

<div class="topic-metadata">

**Author:** [@raff](https://discourse.julialang.org/u/raff)\
**Replies:** 6\
**Last updated:** [May 5, 2020, 4:12pm UTC](https://discourse.julialang.org/t/error-variable-inside-a-loop/21504 "2020-05-05T16:12:08Z")

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I do not understand why it’s an error: x = 0 while x \< 5 x += 1 println(x) end I am using Julia 1.1.0 on Windows. This is the error msg: ERROR: UndefVarError: x not defined Stacktrace: \[1\] top-level scope at …

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## [How to enforce parametric types parameters in this case?](https://discourse.julialang.org/t/how-to-enforce-parametric-types-parameters-in-this-case/38815)

<div class="topic-metadata">

**Author:** [@HenriDeh](https://discourse.julialang.org/u/HenriDeh)\
**Replies:** 1\
**Last updated:** [May 5, 2020, 3:47pm UTC](https://discourse.julialang.org/t/how-to-enforce-parametric-types-parameters-in-this-case/38815 "2020-05-05T15:47:21Z")

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Hello. Since Normal{Float64} \<: UnivariateDistribution I would like to enforce that a Distribution field has a type parameter identical to the type of another field. Let me show you an example that does not work: using…

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## [Flux, higher order derivatives and forward mode](https://discourse.julialang.org/t/flux-higher-order-derivatives-and-forward-mode/38805)

<div class="topic-metadata">

**Author:** [@jw3126](https://discourse.julialang.org/u/jw3126)\
**Replies:** 4\
**Last updated:** [May 5, 2020, 3:23pm UTC](https://discourse.julialang.org/t/flux-higher-order-derivatives-and-forward-mode/38805 "2020-05-05T15:23:05Z")

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I would like to minimize a functional that involves computing partial derivatives. As a toy problem, I want to find a function u(pt) that minimizes ∫ ∂ₓ(u)^2 So in this toy case any u that is constant along the x dire…

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## [Watching Julia developer code](https://discourse.julialang.org/t/watching-julia-developer-code/38738)

<div class="topic-metadata">

**Author:** [@Impressium](https://discourse.julialang.org/u/Impressium)\
**Replies:** 6\
**Last updated:** [May 5, 2020, 3:13pm UTC](https://discourse.julialang.org/t/watching-julia-developer-code/38738 "2020-05-05T15:13:10Z")

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I really like watch other developer to code. It’s very interesting how they do stuff and in general the workflow of others. I learned a lot this way and would love to learn even more that way. Since it’s so easy to reco…

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## [Live stresm of attempt at parquet writer](https://discourse.julialang.org/t/live-stresm-of-attempt-at-parquet-writer/38813)

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**Author:** [@xiaodai](https://discourse.julialang.org/u/xiaodai)\
**Replies:** 0\
**Last updated:** [May 5, 2020, 3:11pm UTC](https://discourse.julialang.org/t/live-stresm-of-attempt-at-parquet-writer/38813 "2020-05-05T15:11:50Z")

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Attempt to make a parquet writer in pure Julia - YouTube i will live stream my attempt at writing a parquet writer in pure Julia

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