# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1890

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

**Page:** 1891

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## [Any methods to let a custom function automatically run by GC after each garbage collection operation?](https://discourse.julialang.org/t/any-methods-to-let-a-custom-function-automatically-run-by-gc-after-each-garbage-collection-operation/30423)

<div class="topic-metadata">

**Author:** [@runapp](https://discourse.julialang.org/u/runapp)\
**Replies:** 3\
**Last updated:** [November 2, 2019, 1:37pm UTC](https://discourse.julialang.org/t/any-methods-to-let-a-custom-function-automatically-run-by-gc-after-each-garbage-collection-operation/30423 "2019-11-02T13:37:18Z")

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I want to remove some WeakRef related resources, e.g. struct Blah dummy::String end a = Blah("abc") b = Dict() b\["a"\] = WeakRef(a) function do\_cleaning() for (k, v) in b if v.value == nothing …

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## [CICLE FOR and DICTIONARY](https://discourse.julialang.org/t/cicle-for-and-dictionary/30614)

<div class="topic-metadata">

**Author:** [@Caterina\_Cerutti](https://discourse.julialang.org/u/Caterina_Cerutti)\
**Replies:** 2\
**Last updated:** [November 2, 2019, 10:18am UTC](https://discourse.julialang.org/t/cicle-for-and-dictionary/30614 "2019-11-02T10:18:55Z")

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I have to write a FOR’s cicle from 1 to 100 and then I have to create a “Dict” ,Called squares, which contains as key the int number and as elements their squares. I have written For i in 1:100 Squares=Dict(i=\>i^2) E…

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## [Julia Package for Unit Conversion](https://discourse.julialang.org/t/julia-package-for-unit-conversion/30605)

<div class="topic-metadata">

**Author:** [@Usor](https://discourse.julialang.org/u/Usor)\
**Replies:** 6\
**Last updated:** [November 2, 2019, 9:44am UTC](https://discourse.julialang.org/t/julia-package-for-unit-conversion/30605 "2019-11-02T09:44:07Z")

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Not exactly my first steps, but I saw no other place to post this. Is there a Julia package taking care of unit conversions (like converting metres to miles, etc.)?

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## [Sparse arrays "\\"](https://discourse.julialang.org/t/sparse-arrays/30606)

<div class="topic-metadata">

**Author:** [@JuhaHeiskala](https://discourse.julialang.org/u/JuhaHeiskala)\
**Replies:** 2\
**Last updated:** [November 2, 2019, 9:00am UTC](https://discourse.julialang.org/t/sparse-arrays/30606 "2019-11-02T09:00:44Z")

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Apparently “A\\b” is not fully supported for both A and b being sparse arrays. using SparseArrays A=sprand(10,10,0.4) b=sprand(10,10,0.3) A\\b ERROR: MethodError: no method matching ldiv!(::SuiteSparse.UMFPACK.Umfpack…

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## [Resolving a module by its name?](https://discourse.julialang.org/t/resolving-a-module-by-its-name/30569)

<div class="topic-metadata">

**Author:** [@gcv](https://discourse.julialang.org/u/gcv)\
**Replies:** 9\
**Last updated:** [November 2, 2019, 5:51am UTC](https://discourse.julialang.org/t/resolving-a-module-by-its-name/30569 "2019-11-02T05:51:13Z")

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Given an arbitrary module name as a symbol, and an expression, what is the correct way to evaluate the expression in the context of the module? For example, suppose I have the following tuple: in = (ns = :MyModule, exp…

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## [The definition of free type variable](https://discourse.julialang.org/t/the-definition-of-free-type-variable/30575)

<div class="topic-metadata">

**Author:** [@alligatorme](https://discourse.julialang.org/u/alligatorme)\
**Replies:** 3\
**Last updated:** [November 1, 2019, 1:39pm UTC](https://discourse.julialang.org/t/the-definition-of-free-type-variable/30575 "2019-11-01T13:39:10Z")

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In v1.2 manual, the free type varialbe is defined as “We say that a variable V is free in type T if T does not contain the UnionAll that introduces variable V.” But in the context, it seems to be “does” instead of “does…

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## [Compiler determines return value(!) but still generates additional code](https://discourse.julialang.org/t/compiler-determines-return-value-but-still-generates-additional-code/27117)

<div class="topic-metadata">

**Author:** [@martink](https://discourse.julialang.org/u/martink)\
**Replies:** 1\
**Last updated:** [November 2, 2019, 12:48am UTC](https://discourse.julialang.org/t/compiler-determines-return-value-but-still-generates-additional-code/27117 "2019-11-02T00:48:15Z")

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Hello This is my first contribution to this Julia forum. I hope my issue belongs to the “Performance” category, if not i would be glad if someone can tell me a more appropriate place. I ran into an issue with a functio…

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## [Optimization level when running files with include() in the REPL](https://discourse.julialang.org/t/optimization-level-when-running-files-with-include-in-the-repl/30566)

<div class="topic-metadata">

**Author:** [@aortizb](https://discourse.julialang.org/u/aortizb)\
**Replies:** 1\
**Last updated:** [November 2, 2019, 12:30am UTC](https://discourse.julialang.org/t/optimization-level-when-running-files-with-include-in-the-repl/30566 "2019-11-02T00:30:15Z")

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I know from the user manual that: julia -O -- file.jl has a default optimization level of 3. I have few questions regarding the optimization level: If “file.jl” is run in the REPL using: include("file.jl") what is…

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## [Fitting a Weibull distribution to values](https://discourse.julialang.org/t/fitting-a-weibull-distribution-to-values/30600)

<div class="topic-metadata">

**Author:** [@ramonz](https://discourse.julialang.org/u/ramonz)\
**Replies:** 2\
**Last updated:** [November 1, 2019, 7:11pm UTC](https://discourse.julialang.org/t/fitting-a-weibull-distribution-to-values/30600 "2019-11-01T19:11:51Z")

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Hello again I would like to fit a set of values to a Weibull distribution but the fitting is still not implemented in the Distributions.jl package for this type of Distribution Distribution Fitting · Distributions.jl. …

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## [Julia Packages and Github](https://discourse.julialang.org/t/julia-packages-and-github/26196)

<div class="topic-metadata">

**Author:** [@Henrique\_Becker](https://discourse.julialang.org/u/Henrique_Becker)\
**Replies:** 17\
**Last updated:** [November 1, 2019, 6:41pm UTC](https://discourse.julialang.org/t/julia-packages-and-github/26196 "2019-11-01T18:41:07Z")

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I am interested in creating a GitHub repository for part of my PhD. The repository will be mostly Julia code that can be shipped as a package, but will also contain a latex directory for writing a paper related to the co…

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## [Can't see Julia in Jupyter's "new" menu](https://discourse.julialang.org/t/cant-see-julia-in-jupyters-new-menu/30596)

<div class="topic-metadata">

**Author:** [@Caterina\_Cerutti](https://discourse.julialang.org/u/Caterina_Cerutti)\
**Replies:** 2\
**Last updated:** [November 1, 2019, 6:04pm UTC](https://discourse.julialang.org/t/cant-see-julia-in-jupyters-new-menu/30596 "2019-11-01T18:04:08Z")

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I can’t see Julia in Jupyter’s new. I have anaconda3 and Julia 1.2.0. I have written using Pkg and PKg.add(“IJulia”) and this procedure must be corrected. I cannot understand why. Can someone help me? PLEASE!

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## [Help understanding broadcasted pipe operator](https://discourse.julialang.org/t/help-understanding-broadcasted-pipe-operator/30591)

<div class="topic-metadata">

**Author:** [@jonniedie](https://discourse.julialang.org/u/jonniedie)\
**Replies:** 4\
**Last updated:** [November 1, 2019, 3:41pm UTC](https://discourse.julialang.org/t/help-understanding-broadcasted-pipe-operator/30591 "2019-11-01T15:41:13Z")

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I would expect the result of \[1, 2\] .|\> u-\>u^2 |\> sum to give the answer 5 since \[1, 2\] .|\> u-\>u^2 gives 2-element Array{Int64,1}: 1 4 and \[1, 4\] |\> sum gives 5. Instead I am getting \[1, 2\] .|\> u-\>u^2 |\> sum …

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## [Does Julia run in Azure?](https://discourse.julialang.org/t/does-julia-run-in-azure/30589)

<div class="topic-metadata">

**Author:** [@BLI](https://discourse.julialang.org/u/BLI)\
**Replies:** 4\
**Last updated:** [November 1, 2019, 3:30pm UTC](https://discourse.julialang.org/t/does-julia-run-in-azure/30589 "2019-11-01T15:30:00Z")

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I confess – I have never used Azure, and know little of it. My understanding is that it involves using a web browser as a terminal window, and run code via distant log-in – using pre-installed software, and with flexibil…

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## [Dot syntax for anonymous functions](https://discourse.julialang.org/t/dot-syntax-for-anonymous-functions/30581)

<div class="topic-metadata">

**Author:** [@ludwig-austermann](https://discourse.julialang.org/u/ludwig-austermann)\
**Replies:** 5\
**Last updated:** [November 1, 2019, 3:06pm UTC](https://discourse.julialang.org/t/dot-syntax-for-anonymous-functions/30581 "2019-11-01T15:06:18Z")

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Hi, in mathematics we use this syntax of • to represent (anonymous) functions. For instance ||•|| is then equivalent to writing x |–\> ||x||. My question is, is there such syntax in julia? If not, I’d love to see the, …

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## [JULIA\_NUM\_THREADS and physical cores](https://discourse.julialang.org/t/julia-num-threads-and-physical-cores/30573)

<div class="topic-metadata">

**Author:** [@ArnoStrouwen](https://discourse.julialang.org/u/ArnoStrouwen)\
**Replies:** 3\
**Last updated:** [November 1, 2019, 2:31pm UTC](https://discourse.julialang.org/t/julia-num-threads-and-physical-cores/30573 "2019-11-01T14:31:44Z")

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In the documentation about JULIA\_NUM\_THREADS it states: “If $JULIA\_NUM\_THREADS exceeds the number of available physical CPU cores, then the number of threads is set to the number of cores.” What exactly is a physical c…

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## [Intended audience for the manual](https://discourse.julialang.org/t/intended-audience-for-the-manual/30586)

<div class="topic-metadata">

**Author:** [@tim.holy](https://discourse.julialang.org/u/tim.holy)\
**Replies:** 2\
**Last updated:** [November 1, 2019, 2:31pm UTC](https://discourse.julialang.org/t/intended-audience-for-the-manual/30586 "2019-11-01T14:31:22Z")

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With an increasing number of options for learning Julia—and especially the exciting announcement about the freeing of JuliaAcademy—I wonder if it’s worth having a discussion about the intended audience for any “official”…

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## [BoundsError: attempt to access "attempt to access a data frame with 6 columns at index 14"](https://discourse.julialang.org/t/boundserror-attempt-to-access-attempt-to-access-a-data-frame-with-6-columns-at-index-14/30546)

<div class="topic-metadata">

**Author:** [@Irene\_Marchand](https://discourse.julialang.org/u/Irene_Marchand)\
**Replies:** 3\
**Last updated:** [November 1, 2019, 2:11pm UTC](https://discourse.julialang.org/t/boundserror-attempt-to-access-attempt-to-access-a-data-frame-with-6-columns-at-index-14/30546 "2019-11-01T14:11:52Z")

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Hello everyone, I am a little confused and I need your help because I am not able to understand my error. I wrote this two functions but for both of them I have the following error: BoundsError: attempt to access “att…

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## [Julia Packages Peacefully Coexisting in Multi-language Github Projects](https://discourse.julialang.org/t/julia-packages-peacefully-coexisting-in-multi-language-github-projects/30582)

<div class="topic-metadata">

**Author:** [@zot](https://discourse.julialang.org/u/zot)\
**Replies:** 0\
**Last updated:** [November 1, 2019, 1:08pm UTC](https://discourse.julialang.org/t/julia-packages-peacefully-coexisting-in-multi-language-github-projects/30582 "2019-11-01T13:08:31Z")

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I have a project that should include packages for several different languages (back end code), along with some common artifacts (front end things HTML, JS, and CSS). Is there a way to handle this in Julia? Ideally I’d l…

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## [Advice on working with a "persistent" Julia Docker image](https://discourse.julialang.org/t/advice-on-working-with-a-persistent-julia-docker-image/30574)

<div class="topic-metadata">

**Author:** [@xiaodai](https://discourse.julialang.org/u/xiaodai)\
**Replies:** 1\
**Last updated:** [November 1, 2019, 12:27pm UTC](https://discourse.julialang.org/t/advice-on-working-with-a-persistent-julia-docker-image/30574 "2019-11-01T12:27:32Z")

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I am using Julia docker but I want to make the packages I install persist across sessions. Is the best way to just mount a directory using the -v option and point Julia to that directory for all package installs? e.g. …

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## [Is it possible to integrate the similar functions into one?](https://discourse.julialang.org/t/is-it-possible-to-integrate-the-similar-functions-into-one/30576)

<div class="topic-metadata">

**Author:** [@Yan](https://discourse.julialang.org/u/Yan)\
**Replies:** 7\
**Last updated:** [November 1, 2019, 12:00pm UTC](https://discourse.julialang.org/t/is-it-possible-to-integrate-the-similar-functions-into-one/30576 "2019-11-01T12:00:35Z")

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Is it possible to integrate the similar functions into one, by expending its abilities. For instance: max; maximum; findmax.

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## [How to diasble documentation-on-hoover?](https://discourse.julialang.org/t/how-to-diasble-documentation-on-hoover/30577)

<div class="topic-metadata">

**Author:** [@sylvaticus](https://discourse.julialang.org/u/sylvaticus)\
**Replies:** 1\
**Last updated:** [November 1, 2019, 10:54am UTC](https://discourse.julialang.org/t/how-to-diasble-documentation-on-hoover/30577 "2019-11-01T10:54:21Z")

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In my installation, the documentation-on-hoover works when it wants to work, and I suspect it is slowing down a lot the user experience. Is there an option (I couldn’t get it in the Atom package settings) to disable it …

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## [Matplotlib Jupyter extension and Plots/PyPlot.jl?](https://discourse.julialang.org/t/matplotlib-jupyter-extension-and-plots-pyplot-jl/30579)

<div class="topic-metadata">

**Author:** [@oschulz](https://discourse.julialang.org/u/oschulz)\
**Replies:** 0\
**Last updated:** [November 1, 2019, 10:51am UTC](https://discourse.julialang.org/t/matplotlib-jupyter-extension-and-plots-pyplot-jl/30579 "2019-11-01T10:51:25Z")

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Did anyone manage to make the Matplotlib Jupyter extension work with PyPlot.jl resp. Plots with the PyPlot backend?

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## [Array{\<:Any} is not the same as Array{\<:}?](https://discourse.julialang.org/t/array-any-is-not-the-same-as-array/30567)

<div class="topic-metadata">

**Author:** [@ablaom](https://discourse.julialang.org/u/ablaom)\
**Replies:** 5\
**Last updated:** [November 1, 2019, 10:39am UTC](https://discourse.julialang.org/t/array-any-is-not-the-same-as-array/30567 "2019-11-01T10:39:30Z")

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julia\> Array{\<:Any} == Array{\<:} false So what’s the difference?

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## [Automatic differentiation of complex valued functions](https://discourse.julialang.org/t/automatic-differentiation-of-complex-valued-functions/30263)

<div class="topic-metadata">

**Author:** [@jtravs](https://discourse.julialang.org/u/jtravs)\
**Replies:** 30\
**Last updated:** [November 1, 2019, 8:44am UTC](https://discourse.julialang.org/t/automatic-differentiation-of-complex-valued-functions/30263 "2019-11-01T08:44:17Z")

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Does anyone know if a Julia automatic differentiation package that supports complex valued functions (with real argument)? I have been using ForwardDiff.jl but it is missing this functionality: https://github.com/JuliaD…

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## [How to Create new method signature on union of types](https://discourse.julialang.org/t/how-to-create-new-method-signature-on-union-of-types/30375)

<div class="topic-metadata">

**Author:** [@Fisheryu1234](https://discourse.julialang.org/u/Fisheryu1234)\
**Replies:** 3\
**Last updated:** [November 1, 2019, 8:14am UTC](https://discourse.julialang.org/t/how-to-create-new-method-signature-on-union-of-types/30375 "2019-11-01T08:14:46Z")

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First we create a composite type AffineExpression using struct struct AffineExpression variables::Vector{Variable} coeffs::Vector{Float64} constant::Float64 end Then we define the expression “+” as AffineE…

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## [Precompiling Turing package failing](https://discourse.julialang.org/t/precompiling-turing-package-failing/30485)

<div class="topic-metadata">

**Author:** [@wattsmo](https://discourse.julialang.org/u/wattsmo)\
**Replies:** 5\
**Last updated:** [November 1, 2019, 7:52am UTC](https://discourse.julialang.org/t/precompiling-turing-package-failing/30485 "2019-11-01T07:52:26Z")

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I have been trying to use the Turing.jl package, MacOS v10.15, I successfully added the package Turing v0.7.0, with dependent packages Zygote v0.3.0, IRTools v0.3.0 but when executing: using Turing I get precompile …

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## [Nested parallelization in Julia?](https://discourse.julialang.org/t/nested-parallelization-in-julia/30568)

<div class="topic-metadata">

**Author:** [@bashonubuntu](https://discourse.julialang.org/u/bashonubuntu)\
**Replies:** 4\
**Last updated:** [November 1, 2019, 6:30am UTC](https://discourse.julialang.org/t/nested-parallelization-in-julia/30568 "2019-11-01T06:30:21Z")

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Hello, I was curious to know if there has been some thought regarding nested parallelization in julia. For example, a typical parallelizable routine with a for loop inside may look like function my\_parallel\_function() …

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## [Why does in-place array assignment behave differently here?](https://discourse.julialang.org/t/why-does-in-place-array-assignment-behave-differently-here/30532)

<div class="topic-metadata">

**Author:** [@groovyda](https://discourse.julialang.org/u/groovyda)\
**Replies:** 17\
**Last updated:** [November 1, 2019, 4:58am UTC](https://discourse.julialang.org/t/why-does-in-place-array-assignment-behave-differently-here/30532 "2019-11-01T04:58:47Z")

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Hi - I’m new to Julia, been playing around a bit. I’ve been struggling to understand the below. I have some code where I need to switch some values in an array. I get (surprisingly) different results if I use w\[3\], w\[2\]…

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## [Distributions getting started example does not work](https://discourse.julialang.org/t/distributions-getting-started-example-does-not-work/30557)

<div class="topic-metadata">

**Author:** [@ramonz](https://discourse.julialang.org/u/ramonz)\
**Replies:** 4\
**Last updated:** [October 31, 2019, 11:26pm UTC](https://discourse.julialang.org/t/distributions-getting-started-example-does-not-work/30557 "2019-10-31T23:26:57Z")

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Hello After trying the “Getting started example” in Distributions Package · Distributions.jl documentation I get an error which I wasn´t expecting. \> using Random, Distributions \> Random.seed!(123) # Setting the seed \>…

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## [Trying to bend my mind to Julia's way](https://discourse.julialang.org/t/trying-to-bend-my-mind-to-julias-way/30514)

<div class="topic-metadata">

**Author:** [@LStoleriu](https://discourse.julialang.org/u/LStoleriu)\
**Replies:** 9\
**Last updated:** [October 31, 2019, 9:41pm UTC](https://discourse.julialang.org/t/trying-to-bend-my-mind-to-julias-way/30514 "2019-10-31T21:41:42Z")

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Hi everyone, I’m a C&Maple physicist trying to learn the “true” Julia way of solving problems. As a small project I’m trying to solve a nonlinear equation doing something like that: using NLsolve Nsteps = 101 Hk = 1…

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