# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1827

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

**Page:** 1828

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## [Performance gotcha in linear algebra lu()](https://discourse.julialang.org/t/performance-gotcha-in-linear-algebra-lu/18128)

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**Author:** [@PetrKryslUCSD](https://discourse.julialang.org/u/PetrKryslUCSD)\
**Replies:** 33\
**Last updated:** [February 11, 2020, 5:43am UTC](https://discourse.julialang.org/t/performance-gotcha-in-linear-algebra-lu/18128 "2020-02-11T05:43:02Z")

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Curiosity killed the cat. I know. But I was curious: how would a naïve implementation of the LU factorization fare compared to what is built in and supported by BLAS 1, 2, 3? The result surprised me as I was able to beat…

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## [ELI5: why is it not possible yet to create standalone binaries using Julia?](https://discourse.julialang.org/t/eli5-why-is-it-not-possible-yet-to-create-standalone-binaries-using-julia/34439)

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**Author:** [@Ronis\_BR](https://discourse.julialang.org/u/Ronis_BR)\
**Replies:** 7\
**Last updated:** [February 11, 2020, 4:16am UTC](https://discourse.julialang.org/t/eli5-why-is-it-not-possible-yet-to-create-standalone-binaries-using-julia/34439 "2020-02-11T04:16:04Z")

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Hi! My knowledge about compilers is very limited. I am wondering: since Julia creates machine code using LLVM, why I cannot compile standalone software? If I use PackageCompiler, for example, I can create a binary, but …

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## [Using a dev --local package in module](https://discourse.julialang.org/t/using-a-dev-local-package-in-module/34323)

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**Author:** [@ric.cioffi](https://discourse.julialang.org/u/ric.cioffi)\
**Replies:** 7\
**Last updated:** [February 11, 2020, 1:04am UTC](https://discourse.julialang.org/t/using-a-dev-local-package-in-module/34323 "2020-02-11T01:04:24Z")

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Let’s say I have a module MyModule in which I want to use a modified version of a registered package, for instance DifferentialEquations. In order not to “pollute” any other environment I can dev --local DifferentialEqua…

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## [4 major problems of pattern matching in Julia](https://discourse.julialang.org/t/4-major-problems-of-pattern-matching-in-julia/34392)

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**Author:** [@thautwarm](https://discourse.julialang.org/u/thautwarm)\
**Replies:** 19\
**Last updated:** [February 10, 2020, 10:27pm UTC](https://discourse.julialang.org/t/4-major-problems-of-pattern-matching-in-julia/34392 "2020-02-10T22:27:38Z")

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Despite of the notation issues of existing Julia macro libraries for pattern matching, based on my experience as a concerned user and developer, I hereby propose 4 major problems preventing us from bringing out good eno…

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## [Linear programming with Jump](https://discourse.julialang.org/t/linear-programming-with-jump/34192)

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**Author:** [@bandaya](https://discourse.julialang.org/u/bandaya)\
**Replies:** 8\
**Last updated:** [February 10, 2020, 10:10pm UTC](https://discourse.julialang.org/t/linear-programming-with-jump/34192 "2020-02-10T22:10:50Z")

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I am trying to write a linear programming problem problem in JuMP but I am getting error messages. I have given my code below, and I believe the issue is in definition of the constraint. Please can someone help to fix t…

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## [Problems in obtaing of the Relative Gap](https://discourse.julialang.org/t/problems-in-obtaing-of-the-relative-gap/34433)

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**Author:** [@angeloaliano1](https://discourse.julialang.org/u/angeloaliano1)\
**Replies:** 1\
**Last updated:** [February 10, 2020, 9:47pm UTC](https://discourse.julialang.org/t/problems-in-obtaing-of-the-relative-gap/34433 "2020-02-10T21:47:14Z")

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I have the following simple problem: using JuMP using CPLEX m = Model(with\_optimizer(CPLEX.Optimizer)) c = \[ 1; 2; 5\] A = \[-1 1 3; 1 3 -7\] b = \[-5; 10\] @variable(m, x\[1:3\] \>= 0) @objective(m, Max, sum( c\[i\]\*x…

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## [IJulia/Jupyter and Powershell](https://discourse.julialang.org/t/ijulia-jupyter-and-powershell/34434)

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**Author:** [@David\_Ortley](https://discourse.julialang.org/u/David_Ortley)\
**Replies:** 1\
**Last updated:** [February 10, 2020, 9:18pm UTC](https://discourse.julialang.org/t/ijulia-jupyter-and-powershell/34434 "2020-02-10T21:18:44Z")

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I’m trying to get Jupyter setup and running from the repl started in Powershell on Windows 10. While I finally was able to find the token by hunting for a jupyter executable in $HOME\\.julia\\conda\\3\\Scripts\\jupyter.exe, …

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## [Not a great example](https://discourse.julialang.org/t/not-a-great-example/34402)

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**Author:** [@qsong](https://discourse.julialang.org/u/qsong)\
**Replies:** 9\
**Last updated:** [February 10, 2020, 8:19pm UTC](https://discourse.julialang.org/t/not-a-great-example/34402 "2020-02-10T20:19:45Z")

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My two cents about an example by @Elrod: I just happen to see this example but the original post has been closed by @StefanKarpinski . As I saw many vips in this forum like this particular example I feel a little confus…

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## [How to make a callback including variables in definition](https://discourse.julialang.org/t/how-to-make-a-callback-including-variables-in-definition/34431)

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**Author:** [@xixit](https://discourse.julialang.org/u/xixit)\
**Replies:** 0\
**Last updated:** [February 10, 2020, 7:12pm UTC](https://discourse.julialang.org/t/how-to-make-a-callback-including-variables-in-definition/34431 "2020-02-10T19:12:33Z")

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Hi, I want to make a callback function set for my differential equation. The problem is I want to make it flexible so in future I can change any desireable callback function without changing the code. It’s a simple contr…

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## [Best way to define methods for SparseArray function based on eltype?](https://discourse.julialang.org/t/best-way-to-define-methods-for-sparsearray-function-based-on-eltype/34429)

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**Author:** [@squirrel](https://discourse.julialang.org/u/squirrel)\
**Replies:** 1\
**Last updated:** [February 10, 2020, 7:17pm UTC](https://discourse.julialang.org/t/best-way-to-define-methods-for-sparsearray-function-based-on-eltype/34429 "2020-02-10T19:17:36Z")

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I have two methods I want to write for a function. I expect both of them to be passed two SparseVectors, but would like to keep it open for any type of Array. I want the compiler to pick between the methods based on the e…

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## [Is there a way cap memory usage to keep MyBinder from crashing?](https://discourse.julialang.org/t/is-there-a-way-cap-memory-usage-to-keep-mybinder-from-crashing/32325)

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**Author:** [@marius311](https://discourse.julialang.org/u/marius311)\
**Replies:** 1\
**Last updated:** [February 10, 2020, 7:14pm UTC](https://discourse.julialang.org/t/is-there-a-way-cap-memory-usage-to-keep-mybinder-from-crashing/32325 "2020-02-10T19:14:59Z")

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MyBinder has a 2GB memory cap. I have a package which used to load fine on there, but recent compiler improvements in 1.3, which although they improve speed (thank you devs :pray:), it comes at the cost of more memory us…

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## [How to find in Array of Pair?](https://discourse.julialang.org/t/how-to-find-in-array-of-pair/34426)

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**Author:** [@programista](https://discourse.julialang.org/u/programista)\
**Replies:** 1\
**Last updated:** [February 10, 2020, 6:16pm UTC](https://discourse.julialang.org/t/how-to-find-in-array-of-pair/34426 "2020-02-10T18:16:51Z")

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Hot to find in head1 “Content-Type” ? ‘’’ julia\> head1 40-element Array{Pair{SubString{String},SubString{String}},1}: “Accept-Ranges” =\> “bytes” "Age" =\> "0" "Cache-C…

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## [How can I optimize recurrent networks in Flux?](https://discourse.julialang.org/t/how-can-i-optimize-recurrent-networks-in-flux/34425)

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**Author:** [@jmeeks29ig](https://discourse.julialang.org/u/jmeeks29ig)\
**Replies:** 0\
**Last updated:** [February 10, 2020, 5:15pm UTC](https://discourse.julialang.org/t/how-can-i-optimize-recurrent-networks-in-flux/34425 "2020-02-10T17:15:45Z")

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Hi, I posted a question in stackoverflow (optimization - How can I optimize a recurrent network in Julia with Flux? - Stack Overflow) regarding the performance of Flux in using a recurrent neural network. I have been ge…

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## [OutOfMemoryError() while solving a linear system](https://discourse.julialang.org/t/outofmemoryerror-while-solving-a-linear-system/33921)

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**Author:** [@AhmedAlreweny](https://discourse.julialang.org/u/AhmedAlreweny)\
**Replies:** 10\
**Last updated:** [February 10, 2020, 3:59pm UTC](https://discourse.julialang.org/t/outofmemoryerror-while-solving-a-linear-system/33921 "2020-02-10T15:59:06Z")

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I am trying to solve a linear system with the direct solver (backslash operator). My matrix is sparse,square and unsymmetric. The system is defined as Ax=b, where A is defined to be a SparseMatrixCSC with dimensions = 8…

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## [CUDAnative.jl failed to initialize](https://discourse.julialang.org/t/cudanative-jl-failed-to-initialize/34342)

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**Author:** [@Ferran\_Mazzanti](https://discourse.julialang.org/u/Ferran_Mazzanti)\
**Replies:** 11\
**Last updated:** [February 10, 2020, 3:54pm UTC](https://discourse.julialang.org/t/cudanative-jl-failed-to-initialize/34342 "2020-02-10T15:54:51Z")

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Hi, I’ve been using CUDAnative, CUDAdrv and CuArrays extensively in my ubuntu box for few months now, but somehow after an update of julia packages (which included these) I can no longer use them using CUDAnative \> \[ I…

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## [Problem with parsing tag(::HTMLText) in Gumbo](https://discourse.julialang.org/t/problem-with-parsing-tag-htmltext-in-gumbo/34421)

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**Author:** [@programista](https://discourse.julialang.org/u/programista)\
**Replies:** 0\
**Last updated:** [February 10, 2020, 3:53pm UTC](https://discourse.julialang.org/t/problem-with-parsing-tag-htmltext-in-gumbo/34421 "2020-02-10T15:53:12Z")

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Sombody can help ? Why HTMLText stoped it ? julia\> using HTTP,Gumbo,AbstractTrees julia\> url=url="http://bbc.com"; julia\> r=HTTP.request("GET", url; retries=4, cookies=true); julia\> doc=parsehtml(String(r.body)); j…

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## [How to plot the solution of two different (but almost identical) differential equations on same plot?](https://discourse.julialang.org/t/how-to-plot-the-solution-of-two-different-but-almost-identical-differential-equations-on-same-plot/34419)

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**Author:** [@HelgavonLichtenstein](https://discourse.julialang.org/u/HelgavonLichtenstein)\
**Replies:** 2\
**Last updated:** [February 10, 2020, 3:23pm UTC](https://discourse.julialang.org/t/how-to-plot-the-solution-of-two-different-but-almost-identical-differential-equations-on-same-plot/34419 "2020-02-10T15:23:15Z")

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Hello, I have two differential equations which calculate how much area a fleet of boats can cover. The two equations are nearly identical apart from how the area coverage is calculated. I would like to graph the outcome…

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## [Unknown allocation](https://discourse.julialang.org/t/unknown-allocation/34365)

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**Author:** [@tomtom](https://discourse.julialang.org/u/tomtom)\
**Replies:** 5\
**Last updated:** [February 10, 2020, 2:53pm UTC](https://discourse.julialang.org/t/unknown-allocation/34365 "2020-02-10T14:53:17Z")

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I’m trying to do lazy evaluations as follows: struct V data::Vector{Int} end f(v, x) = Base.broadcasted(+, x, v.data) g(v, x) = Base.broadcasted(\*, x, v.data) const x = \[1, 2\] const a = V(\[3, 4\]) const b = V(\[5, 6\]…

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## [Training dataset and reporting MSE](https://discourse.julialang.org/t/training-dataset-and-reporting-mse/34391)

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**Author:** [@Praise](https://discourse.julialang.org/u/Praise)\
**Replies:** 6\
**Last updated:** [February 10, 2020, 2:49pm UTC](https://discourse.julialang.org/t/training-dataset-and-reporting-mse/34391 "2020-02-10T14:49:16Z")

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Hello, I am trying to train dataset using linear regression in julia and then I have to calculate the MSE of the given test dataset. I was wondering what are the best packages to use, and an example of how to do this wit…

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## [Importing Functions from module](https://discourse.julialang.org/t/importing-functions-from-module/34413)

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**Author:** [@samantp](https://discourse.julialang.org/u/samantp)\
**Replies:** 2\
**Last updated:** [February 10, 2020, 2:17pm UTC](https://discourse.julialang.org/t/importing-functions-from-module/34413 "2020-02-10T14:17:56Z")

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I’m quite confused about what exactly a module is. As I understand it a module is just a collection of functions that I can import, similar to a package. So, I have four functions that I want to import that I have put in…

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## [Lazyconstraint not defined using GLPK solver callbacks](https://discourse.julialang.org/t/lazyconstraint-not-defined-using-glpk-solver-callbacks/34012)

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**Author:** [@Espenol](https://discourse.julialang.org/u/Espenol)\
**Replies:** 4\
**Last updated:** [February 10, 2020, 1:51pm UTC](https://discourse.julialang.org/t/lazyconstraint-not-defined-using-glpk-solver-callbacks/34012 "2020-02-10T13:51:22Z")

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Hello! Sorry about the newb question, but I have an issue setting lazy constraint. I follow the example here but don’t have access to licensed solvers so I use the GLPK solver instead of the Gurobi solver by applying th…

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## [What is the fftfreq sampling frequency?](https://discourse.julialang.org/t/what-is-the-fftfreq-sampling-frequency/34406)

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**Author:** [@feanor12](https://discourse.julialang.org/u/feanor12)\
**Replies:** 1\
**Last updated:** [February 10, 2020, 1:35pm UTC](https://discourse.julialang.org/t/what-is-the-fftfreq-sampling-frequency/34406 "2020-02-10T13:35:08Z")

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From my understanding, the sampling frequency is the inverse distance between data points. Is this correct, or do I have to use something else? Maybe an example can make my question a bit clearer. If I want to plot th…

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## [Limit Julia Memory](https://discourse.julialang.org/t/limit-julia-memory/34409)

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**Author:** [@altre](https://discourse.julialang.org/u/altre)\
**Replies:** 0\
**Last updated:** [February 10, 2020, 12:58pm UTC](https://discourse.julialang.org/t/limit-julia-memory/34409 "2020-02-10T12:58:16Z")

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This is basically a question on the still open (but fixed) issue https://github.com/JuliaLang/julia/issues/17987 I’m trying to find the easiest way to limit the memory available for a julia process. The issue above see…

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## [Help with compilation](https://discourse.julialang.org/t/help-with-compilation/34408)

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**Author:** [@CodeLenz](https://discourse.julialang.org/u/CodeLenz)\
**Replies:** 0\
**Last updated:** [February 10, 2020, 12:23pm UTC](https://discourse.julialang.org/t/help-with-compilation/34408 "2020-02-10T12:23:36Z")

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Hi. I used to compile julia in my machine, but now there is this error while compiling libunwind Blockquote checking for a BSD-compatible install… /usr/bin/install -c checking whether build environment is sane… yes …

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## [Julia Flux Right Version](https://discourse.julialang.org/t/julia-flux-right-version/34303)

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**Author:** [@Owolf](https://discourse.julialang.org/u/Owolf)\
**Replies:** 3\
**Last updated:** [February 10, 2020, 11:10am UTC](https://discourse.julialang.org/t/julia-flux-right-version/34303 "2020-02-10T11:10:12Z")

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Hello Everybody, I am new in Julia and Flux. I went through model-zoo and it seems as pretty nice example. However as far I had no luck to make it work. After hours of googling and going through non-consistent informati…

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## [Julia plots error with errorbars in v0.29.0](https://discourse.julialang.org/t/julia-plots-error-with-errorbars-in-v0-29-0/34404)

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**Author:** [@transarcus](https://discourse.julialang.org/u/transarcus)\
**Replies:** 2\
**Last updated:** [February 10, 2020, 10:51am UTC](https://discourse.julialang.org/t/julia-plots-error-with-errorbars-in-v0-29-0/34404 "2020-02-10T10:51:42Z")

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I have been quite happily plotting graphs with errorbars in julia, but today it started to give me an error. I have tried searching for this issue but haven’t been able to find anything. using Plots plot(\[1,2,3,4\],\[1,2,…

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## [UndefVarError for defined function](https://discourse.julialang.org/t/undefvarerror-for-defined-function/34405)

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**Author:** [@samantp](https://discourse.julialang.org/u/samantp)\
**Replies:** 2\
**Last updated:** [February 10, 2020, 10:46am UTC](https://discourse.julialang.org/t/undefvarerror-for-defined-function/34405 "2020-02-10T10:46:33Z")

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I think I may have some syntax error here but I can’t figure out what it is. I am trying to write and use a function called probit. In the long term I would like to save this function into a file but for now I’m just try…

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## [\[ANN\] SolverTraces.jl v0.1.0](https://discourse.julialang.org/t/ann-solvertraces-jl-v0-1-0/34400)

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**Author:** [@jagot](https://discourse.julialang.org/u/jagot)\
**Replies:** 8\
**Last updated:** [February 10, 2020, 10:37am UTC](https://discourse.julialang.org/t/ann-solvertraces-jl-v0-1-0/34400 "2020-02-10T10:37:23Z")

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I just registered SolverTraces.jl, a simple library for creating colourful solver traces in the REPL. I mostly developed this for my Hartree–Fock solver (see picture), but it is general and simple enough to adapt to othe…

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## [Function definition](https://discourse.julialang.org/t/function-definition/34403)

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**Author:** [@samantp](https://discourse.julialang.org/u/samantp)\
**Replies:** 2\
**Last updated:** [February 10, 2020, 10:17am UTC](https://discourse.julialang.org/t/function-definition/34403 "2020-02-10T10:17:24Z")

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So I want to define a new function, probit, from functions that I use in the SpecialFunctions toolbox. i.e. the function itself is a variant of a function found in this toolbox. Right now I have the following function …

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## [Juno Debugger ignores breakpoints](https://discourse.julialang.org/t/juno-debugger-ignores-breakpoints/25988)

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**Author:** [@alequa](https://discourse.julialang.org/u/alequa)\
**Replies:** 9\
**Last updated:** [February 10, 2020, 9:04am UTC](https://discourse.julialang.org/t/juno-debugger-ignores-breakpoints/25988 "2020-02-10T09:04:19Z")

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Hi all, I am new to Julia but I am used to debug with C++ and Python both in gdb and Jetbrains, so I know a bit the idea! I am running a code of someone else, it is fairly complex and several functions are defined with…

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