# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1725

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

**Page:** 1726

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## [Recurrent precompilations](https://discourse.julialang.org/t/recurrent-precompilations/40948)

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**Author:** [@aquarelle332](https://discourse.julialang.org/u/aquarelle332)\
**Replies:** 3\
**Last updated:** [June 8, 2020, 10:56am UTC](https://discourse.julialang.org/t/recurrent-precompilations/40948 "2020-06-08T10:56:23Z")

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Kubuntu 18.04.4 LTS Julia 1.4.2 installed in /usr/local/julia-1.4.2 bashrc modified: PATH=/usr/local/julia-1.4.2/bin:$PATH $HOME/.julia contains: artifacts, compiled, conda, environments, logs, packages, prefs,…

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## [Cplex.jl change parameters and display info](https://discourse.julialang.org/t/cplex-jl-change-parameters-and-display-info/40821)

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**Author:** [@geoffroyleconte](https://discourse.julialang.org/u/geoffroyleconte)\
**Replies:** 4\
**Last updated:** [June 8, 2020, 9:19am UTC](https://discourse.julialang.org/t/cplex-jl-change-parameters-and-display-info/40821 "2020-06-08T09:19:04Z")

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Hello, I am trying to use cplex.jl to solve linear problems without using JuMP or MOI. I want to use the barrier method without presolve and crossover/vertex, so I used these commands: CPLEX.set\_param!(env, "CPX\_PARAM…

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## [What's the use a Project.toml file and the the use of a Manifest.toml in a Julia project?](https://discourse.julialang.org/t/whats-the-use-a-project-toml-file-and-the-the-use-of-a-manifest-toml-in-a-julia-project/22524)

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**Author:** [@xiaodai](https://discourse.julialang.org/u/xiaodai)\
**Replies:** 5\
**Last updated:** [June 8, 2020, 7:20am UTC](https://discourse.julialang.org/t/whats-the-use-a-project-toml-file-and-the-the-use-of-a-manifest-toml-in-a-julia-project/22524 "2020-06-08T07:20:54Z")

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Why are there two .toml files in a Julia project? How are they different? From here it says that a manifest.toml allows other to replicate the set up of the project. So how is the project.toml different?

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## [How to discretize and solve a 3D Poisson Equation with Dirichlet boundary conditions owing to DiffEqOperators](https://discourse.julialang.org/t/how-to-discretize-and-solve-a-3d-poisson-equation-with-dirichlet-boundary-conditions-owing-to-diffeqoperators/40796)

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**Author:** [@RenaudV](https://discourse.julialang.org/u/RenaudV)\
**Replies:** 2\
**Last updated:** [June 8, 2020, 6:37am UTC](https://discourse.julialang.org/t/how-to-discretize-and-solve-a-3d-poisson-equation-with-dirichlet-boundary-conditions-owing-to-diffeqoperators/40796 "2020-06-08T06:37:14Z")

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I love the following example of solving a 1D Poisson equation with DiffEqOperators. However , I struggle to do the analog 3D example. Can somebody indicate me the right steps? The 1D formulation is: using DiffEqOperat…

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## [CSV won't read after dependency issues](https://discourse.julialang.org/t/csv-wont-read-after-dependency-issues/40898)

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**Author:** [@Chris\_Anderson](https://discourse.julialang.org/u/Chris_Anderson)\
**Replies:** 7\
**Last updated:** [June 8, 2020, 4:06am UTC](https://discourse.julialang.org/t/csv-wont-read-after-dependency-issues/40898 "2020-06-08T04:06:53Z")

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I just got into a bit of a dependency hell and ended up clearing and reinstalling many packages. Now, when I try to run programs that have worked before, I get an error when I try to read in my data. My code: df = CSV…

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## [Zygote and StructArrays](https://discourse.julialang.org/t/zygote-and-structarrays/35537)

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**Author:** [@e3c6](https://discourse.julialang.org/u/e3c6)\
**Replies:** 6\
**Last updated:** [June 7, 2020, 11:50pm UTC](https://discourse.julialang.org/t/zygote-and-structarrays/35537 "2020-06-07T23:50:27Z")

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It seems Flux.@functor does not get along with StructArrays? using StructArrays, Flux struct A{SA} s::SA end struct Point x::Float64 y::Float64 end Flux.@functor A Flux.@functor Point a = A(StructArray((Point(i,2…

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## [How to convert Array/Vector{Array{Float64,2}} into an Array{Float64,2} OR how to create plots from them?](https://discourse.julialang.org/t/how-to-convert-array-vector-array-float64-2-into-an-array-float64-2-or-how-to-create-plots-from-them/40942)

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**Author:** [@HelgavonLichtenstein](https://discourse.julialang.org/u/HelgavonLichtenstein)\
**Replies:** 6\
**Last updated:** [June 7, 2020, 11:13pm UTC](https://discourse.julialang.org/t/how-to-convert-array-vector-array-float64-2-into-an-array-float64-2-or-how-to-create-plots-from-them/40942 "2020-06-07T23:13:25Z")

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Hello, I would like to know how to convert from an Array/Vector{Array{Float64,2}} into Array{Float64,2} or how I can create a plot from them. I can convert a Vector{Array{Float64,2}} with 50001 elements 1×8 Array{Float…

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## [Triangular Arrays in julia?](https://discourse.julialang.org/t/triangular-arrays-in-julia/930)

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**Author:** [@Ward9250](https://discourse.julialang.org/u/Ward9250)\
**Replies:** 25\
**Last updated:** [June 7, 2020, 7:12pm UTC](https://discourse.julialang.org/t/triangular-arrays-in-julia/930 "2020-06-07T19:12:07Z")

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Does anyone know if triangular arrays have been implemented in julia or in a package yet?

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## [Replacing values in a data frame](https://discourse.julialang.org/t/replacing-values-in-a-data-frame/40937)

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**Author:** [@Chris\_Anderson](https://discourse.julialang.org/u/Chris_Anderson)\
**Replies:** 7\
**Last updated:** [June 7, 2020, 7:11pm UTC](https://discourse.julialang.org/t/replacing-values-in-a-data-frame/40937 "2020-06-07T19:11:13Z")

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Don’t know if this is the right category for this… I have a dataframe with a column containing averages calculated with the mean function. These values go out several decimal places, but I want to use round() to set it…

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## [Zygote AD Jacobian-vector product](https://discourse.julialang.org/t/zygote-ad-jacobian-vector-product/40857)

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**Author:** [@pavanakumar](https://discourse.julialang.org/u/pavanakumar)\
**Replies:** 5\
**Last updated:** [June 7, 2020, 7:08pm UTC](https://discourse.julialang.org/t/zygote-ad-jacobian-vector-product/40857 "2020-06-07T19:08:04Z")

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Hi I come from the Tapenade source transformation community and use Fortran as my primary language. I recently moved to Julia and slowly adapting to the language. I have problems understanding the algorithmic differenti…

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## [Improving a Program Implementing findall Function](https://discourse.julialang.org/t/improving-a-program-implementing-findall-function/40938)

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**Author:** [@johnrickmanz](https://discourse.julialang.org/u/johnrickmanz)\
**Replies:** 1\
**Last updated:** [June 7, 2020, 6:29pm UTC](https://discourse.julialang.org/t/improving-a-program-implementing-findall-function/40938 "2020-06-07T18:29:00Z")

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I recently seen topics here that says the findall function is quite slow and I think so too most likely if I am dealing with large number of elements say hundreds of thousands or more. An example of what I want is as fol…

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## [Emacs evaluating code in Weave / jmd files?](https://discourse.julialang.org/t/emacs-evaluating-code-in-weave-jmd-files/40849)

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**Author:** [@dlakelan](https://discourse.julialang.org/u/dlakelan)\
**Replies:** 2\
**Last updated:** [June 7, 2020, 5:17pm UTC](https://discourse.julialang.org/t/emacs-evaluating-code-in-weave-jmd-files/40849 "2020-06-07T17:17:30Z")

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I’m writing documents using Weave, which is working great. Of course, I can easily with a single command, convert my document to a Notebook: notebook("..."); However, I work in Emacs, and it’d be great to be able to mo…

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## [Can't seem to get NLsolve to converge](https://discourse.julialang.org/t/cant-seem-to-get-nlsolve-to-converge/40845)

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**Author:** [@Mark\_Williams](https://discourse.julialang.org/u/Mark_Williams)\
**Replies:** 5\
**Last updated:** [June 7, 2020, 5:08pm UTC](https://discourse.julialang.org/t/cant-seem-to-get-nlsolve-to-converge/40845 "2020-06-07T17:08:30Z")

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Please note: I’ve cross posted this question on StackOverflow. here I’m trying to solve a life cycle problem in economics using Julia but I’m having trouble with NLsolve. The model boils down to trying to solve two a t…

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## [Juno save question](https://discourse.julialang.org/t/juno-save-question/40830)

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**Author:** [@Chris\_Anderson](https://discourse.julialang.org/u/Chris_Anderson)\
**Replies:** 4\
**Last updated:** [June 7, 2020, 4:17pm UTC](https://discourse.julialang.org/t/juno-save-question/40830 "2020-06-07T16:17:25Z")

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This is a random, kind of non-Julia, question. I use Atom/Juno. Every time I save a program all of the colored formatting disappears and I can no longer run the program. If I copy/paste my program into a new file the …

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## [Looping over edges in LightGraphs](https://discourse.julialang.org/t/looping-over-edges-in-lightgraphs/40909)

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**Author:** [@erlebach](https://discourse.julialang.org/u/erlebach)\
**Replies:** 8\
**Last updated:** [June 7, 2020, 3:33pm UTC](https://discourse.julialang.org/t/looping-over-edges-in-lightgraphs/40909 "2020-06-07T15:33:40Z")

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I have created a graph with 100,000 vertices and 30 edges per vertex. I would like to loop over the edges to prestore the edge extremities. Thus: # Prestore all the edge nodes nodes = zeros(Int,2,nb\_edges) # 2 second fo…

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## [Pass extra arguments to ODEForwardSensitivityProblem's RHS function](https://discourse.julialang.org/t/pass-extra-arguments-to-odeforwardsensitivityproblems-rhs-function/40933)

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**Author:** [@ca0h](https://discourse.julialang.org/u/ca0h)\
**Replies:** 1\
**Last updated:** [June 7, 2020, 3:22pm UTC](https://discourse.julialang.org/t/pass-extra-arguments-to-odeforwardsensitivityproblems-rhs-function/40933 "2020-06-07T15:22:35Z")

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For DiffEqSensitivity.jl’s ODEForwardSensitivityProblem, I was wondering if we could pass extra arguments to RHS function that are not for sensitivity analysis? In DifferentialEquations.jl, we could pass extra arguments…

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## [Best Julia Computer Graphics in Jupyter?](https://discourse.julialang.org/t/best-julia-computer-graphics-in-jupyter/40873)

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**Author:** [@Jojo\_Dad](https://discourse.julialang.org/u/Jojo_Dad)\
**Replies:** 11\
**Last updated:** [June 7, 2020, 2:19pm UTC](https://discourse.julialang.org/t/best-julia-computer-graphics-in-jupyter/40873 "2020-06-07T14:19:50Z")

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I want to teach a mechanics class using Julia. What’s the best Julia Computer Graphics Package that works in Jupyter?

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## [Absolute value in JuMP](https://discourse.julialang.org/t/absolute-value-in-jump/40911)

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**Author:** [@sobhan](https://discourse.julialang.org/u/sobhan)\
**Replies:** 2\
**Last updated:** [June 7, 2020, 1:52pm UTC](https://discourse.julialang.org/t/absolute-value-in-jump/40911 "2020-06-07T13:52:08Z")

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I’m trying to optimize the absolute value of an affine function, for example, something like: using JuMP model = Model() @variable(model, x) @objective(model, Min, abs(x)) but i get Closest candidates are: abs(::Boo…

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## [Displaying video on a rotating cube](https://discourse.julialang.org/t/displaying-video-on-a-rotating-cube/40920)

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**Author:** [@johnh](https://discourse.julialang.org/u/johnh)\
**Replies:** 1\
**Last updated:** [June 7, 2020, 10:57am UTC](https://discourse.julialang.org/t/displaying-video-on-a-rotating-cube/40920 "2020-06-07T10:57:09Z")

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When the SGI O2 workstation was introduced (ahem) years ago one of the impressive for the time demos was to display moving video on the faces of a wireframe cube which was being rotated on the screen. My memory may be fa…

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## [Set maxiters on OrdinaryDiffEq](https://discourse.julialang.org/t/set-maxiters-on-ordinarydiffeq/40850)

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**Author:** [@Luigi\_Marongiu](https://discourse.julialang.org/u/Luigi_Marongiu)\
**Replies:** 5\
**Last updated:** [June 7, 2020, 12:59pm UTC](https://discourse.julialang.org/t/set-maxiters-on-ordinarydiffeq/40850 "2020-06-07T12:59:12Z")

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Hello, I wrote a differential equation set as follows: function seir!(du, u, p, t) trans\_rate, infect\_rate, recovery\_rate = p λ = trans\_rate \* u\[3\] # force of infection βI κ1 = λ \* u\[1\] …

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## [GLIBCXX\_3.4.26 not found in RCall](https://discourse.julialang.org/t/glibcxx-3-4-26-not-found-in-rcall/29113)

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**Author:** [@yakir12](https://discourse.julialang.org/u/yakir12)\
**Replies:** 16\
**Last updated:** [June 7, 2020, 11:15am UTC](https://discourse.julialang.org/t/glibcxx-3-4-26-not-found-in-rcall/29113 "2020-06-07T11:15:52Z")

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(Also posted on slack#statistics) If anyone has time to look at what must be a basic issue on my side, I’ve posted an issue on RCall.jl that is a show stopper for me: https://github.com/JuliaInterop/RCall.jl/issues/339 …

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## [Package name conflicts](https://discourse.julialang.org/t/package-name-conflicts/40921)

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**Author:** [@heliosdrm](https://discourse.julialang.org/u/heliosdrm)\
**Replies:** 1\
**Last updated:** [June 7, 2020, 11:10am UTC](https://discourse.julialang.org/t/package-name-conflicts/40921 "2020-06-07T11:10:59Z")

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A recent discussion in another thread made me wonder: what are the limitations of the support for duplicated package names, and the practical problems of their possible existence? In the documentation of Pkg and in the J…

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## [Makie Problem](https://discourse.julialang.org/t/makie-problem/40917)

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**Author:** [@Jojo\_Dad](https://discourse.julialang.org/u/Jojo_Dad)\
**Replies:** 1\
**Last updated:** [June 7, 2020, 9:17am UTC](https://discourse.julialang.org/t/makie-problem/40917 "2020-06-07T09:17:09Z")

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When I run import Pkg; Pkg.add("Makie") using Makie I get InitError: could not load library "/Users/jojo/.julia/artifacts/dbb254dca678145c7d79410e96da494cc94f8a13/lib/libavdevice.58.5.100.dylib" dlopen(/Users/jojo/.ju…

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## [Simplifying Constructors](https://discourse.julialang.org/t/simplifying-constructors/40907)

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**Author:** [@virtualgraham](https://discourse.julialang.org/u/virtualgraham)\
**Replies:** 3\
**Last updated:** [June 7, 2020, 7:20am UTC](https://discourse.julialang.org/t/simplifying-constructors/40907 "2020-06-07T07:20:21Z")

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Is there a better way to define a constructor that allows for optional params or a small amount of logic without having to rewrite all the properties three times? mutable struct AcRepertoireIrreducibilityAnalysis \<: Ord…

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## [Creating structures while writing code](https://discourse.julialang.org/t/creating-structures-while-writing-code/40895)

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**Author:** [@erlebach](https://discourse.julialang.org/u/erlebach)\
**Replies:** 5\
**Last updated:** [June 7, 2020, 5:01am UTC](https://discourse.julialang.org/t/creating-structures-while-writing-code/40895 "2020-06-07T05:01:09Z")

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I am working with my own structs for the first time and am having some conceptual problems. Consider the code mutable struct myTest arr::Array{Float64, 1} # arr is an array myTest(eqs::Array{Float64,1}) = new(…

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## [Can not convert an object of type Tuple{Int64, Int64} to an object of type Tuple{}](https://discourse.julialang.org/t/can-not-convert-an-object-of-type-tuple-int64-int64-to-an-object-of-type-tuple/22990)

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**Author:** [@bsnyh](https://discourse.julialang.org/u/bsnyh)\
**Replies:** 9\
**Last updated:** [June 7, 2020, 3:08am UTC](https://discourse.julialang.org/t/can-not-convert-an-object-of-type-tuple-int64-int64-to-an-object-of-type-tuple/22990 "2020-06-07T03:08:30Z")

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mutable struct myTp a::Vector{Int64} b::Tuple{Int64} #myTp() = new(\[\], ()) myTp(a,b) = new(a,b) end function main() c=myTp(\[1,2,3\],(4,5,6)) end main() Can anyone let me know why?

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## [Why isn't the "setrounding" function working the way I expect?](https://discourse.julialang.org/t/why-isnt-the-setrounding-function-working-the-way-i-expect/40891)

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**Author:** [@Lucas\_Queiroz](https://discourse.julialang.org/u/Lucas_Queiroz)\
**Replies:** 13\
**Last updated:** [June 7, 2020, 3:07am UTC](https://discourse.julialang.org/t/why-isnt-the-setrounding-function-working-the-way-i-expect/40891 "2020-06-07T03:07:06Z")

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Why does Julia rounds 0.3 down in my code? julia\> setrounding(BigFloat, RoundUp) MPFRRoundUp::MPFRRoundingMode = 2 julia\> BigFloat(0.3) 0.299999999999999988897769753748434595763683319091796875

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## [easy way to solve problems with tridiagonal matrix](https://discourse.julialang.org/t/easy-way-to-solve-problems-with-tridiagonal-matrix/15715)

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**Author:** [@sahaskn1](https://discourse.julialang.org/u/sahaskn1)\
**Replies:** 4\
**Last updated:** [June 7, 2020, 2:18am UTC](https://discourse.julialang.org/t/easy-way-to-solve-problems-with-tridiagonal-matrix/15715 "2020-06-07T02:18:23Z")

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I’m learning JuliaLang as an alternative to python for its speed. I would like to know if there exist functions in julia for tridiagonal matrix problem typically encountered in quantum kinetic energy operator in coordina…

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## [Setting Julia version for JupyterLab](https://discourse.julialang.org/t/setting-julia-version-for-jupyterlab/40901)

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**Author:** [@pauljurczak](https://discourse.julialang.org/u/pauljurczak)\
**Replies:** 2\
**Last updated:** [June 7, 2020, 1:47am UTC](https://discourse.julialang.org/t/setting-julia-version-for-jupyterlab/40901 "2020-06-07T01:47:35Z")

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I have 2 versions of Julia installed, but only one is visible in JupyterLab. How do I make both of them visible or select the visible one?

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## [Unexpected behavior DifferentialEquations (parabolic ODE) -- large # of steps](https://discourse.julialang.org/t/unexpected-behavior-differentialequations-parabolic-ode-large-of-steps/40886)

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**Author:** [@egcjm](https://discourse.julialang.org/u/egcjm)\
**Replies:** 3\
**Last updated:** [June 6, 2020, 10:32pm UTC](https://discourse.julialang.org/t/unexpected-behavior-differentialequations-parabolic-ode-large-of-steps/40886 "2020-06-06T22:32:31Z")

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\*\* This question is as much about numerics as about use of DifferentialEquations.jl \*\* \*\* This is a toy problem with an analytical solution – I’d like to understand the behavior of DifferentialEquations.jl, not interest…

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