# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1100

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

**Page:** 1101

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## [Any way to achieve the L2 norm of a matrix xx is smaller than 1 in JuMP?](https://discourse.julialang.org/t/any-way-to-achieve-the-l2-norm-of-a-matrix-xx-is-smaller-than-1-in-jump/77660)

<div class="topic-metadata">

**Author:** [@zlq178](https://discourse.julialang.org/u/zlq178)\
**Replies:** 3\
**Last updated:** [March 10, 2022, 3:22am UTC](https://discourse.julialang.org/t/any-way-to-achieve-the-l2-norm-of-a-matrix-xx-is-smaller-than-1-in-jump/77660 "2022-03-10T03:22:41Z")

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I want to achieve the constraint: norm(A) \<= 1, where A is a matrix variable. M = Model(SCS.Optimizer) @variable(M,A\[1:3,1:3\]) @constraint(M, \[1; A\] in SecondOrderCone()) But it shows error：@constraint(M, \[1; A\] in Se…

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## [Extract start and end positions from a PairwiseAlignment](https://discourse.julialang.org/t/extract-start-and-end-positions-from-a-pairwisealignment/77610)

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**Author:** [@rohan.m](https://discourse.julialang.org/u/rohan.m)\
**Replies:** 6\
**Last updated:** [March 10, 2022, 3:02am UTC](https://discourse.julialang.org/t/extract-start-and-end-positions-from-a-pairwisealignment/77610 "2022-03-10T03:02:03Z")

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Hello, I am dealing with PairwiseAlignments of the form: PairwiseAlignment{LongDNASeq, LongDNASeq}: seq: 2 TGTCTTTCGCTGCTGAGGGTAGA 24 | | | | | | | | | | | | | | | | | | | | | | ref: 307 TGTCTTTCGCTGC…

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## [What kind of julia object translates to C's FILE\*](https://discourse.julialang.org/t/what-kind-of-julia-object-translates-to-cs-file/77656)

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**Author:** [@bluesmoon](https://discourse.julialang.org/u/bluesmoon)\
**Replies:** 2\
**Last updated:** [March 10, 2022, 1:54am UTC](https://discourse.julialang.org/t/what-kind-of-julia-object-translates-to-cs-file/77656 "2022-03-10T01:54:05Z")

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I’m on Julia 1.6.5 and trying to redirect verbose messages from LibCURL to a file. In C this would be done by calling curl\_easy\_setopt(CURL \*handle, CURLOPT\_STDERR, FILE \*stream). What kind of a Julia object should I pa…

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## [Comonicon: Pre-1.0 Announcement](https://discourse.julialang.org/t/comonicon-pre-1-0-announcement/77657)

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**Author:** [@Roger-luo](https://discourse.julialang.org/u/Roger-luo)\
**Replies:** 0\
**Last updated:** [March 9, 2022, 11:54pm UTC](https://discourse.julialang.org/t/comonicon-pre-1-0-announcement/77657 "2022-03-09T23:54:36Z")

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The CLI generator Comonicon has been announced for a while and has been tagged 0.12.10 version recently. The interface has been stabilized for a while, thus I’m thinking to release its first 1.0 version. I’d like to see …

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## [Best way to convert a generic QCQP into standard form in JuMP](https://discourse.julialang.org/t/best-way-to-convert-a-generic-qcqp-into-standard-form-in-jump/77593)

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**Author:** [@Shuvomoy\_Das\_Gupta](https://discourse.julialang.org/u/Shuvomoy_Das_Gupta)\
**Replies:** 4\
**Last updated:** [March 9, 2022, 11:46pm UTC](https://discourse.julialang.org/t/best-way-to-convert-a-generic-qcqp-into-standard-form-in-jump/77593 "2022-03-09T23:46:55Z")

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Dear All, I am solving nonconvex quadratically constrained quadratic optimization problems (QCQPs) in JuMP+Gurobi for teaching a recitation class on power system course at MIT (I am a teaching assistant for the course).…

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## [How to pass a void\*\* to ccall?](https://discourse.julialang.org/t/how-to-pass-a-void-to-ccall/77655)

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**Author:** [@ezaron](https://discourse.julialang.org/u/ezaron)\
**Replies:** 2\
**Last updated:** [March 9, 2022, 11:38pm UTC](https://discourse.julialang.org/t/how-to-pass-a-void-to-ccall/77655 "2022-03-09T23:38:23Z")

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Hi: I am trying to call some C code from julia. The header of the C code defines the following: typedef void\* FES; so, I believe FES is a pointer to a Cvoid. The same header file provides this signature for the funct…

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## [How to select rows from a dataframe and then create a dataframe with multiple columns from the selection](https://discourse.julialang.org/t/how-to-select-rows-from-a-dataframe-and-then-create-a-dataframe-with-multiple-columns-from-the-selection/77652)

<div class="topic-metadata">

**Author:** [@anon69491625](https://discourse.julialang.org/u/anon69491625)\
**Replies:** 2\
**Last updated:** [March 9, 2022, 10:07pm UTC](https://discourse.julialang.org/t/how-to-select-rows-from-a-dataframe-and-then-create-a-dataframe-with-multiple-columns-from-the-selection/77652 "2022-03-09T22:07:00Z")

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Hi all noob here I can select the rows I want from a dataframe and create a new data using ONE of the original dataframes columns BUT how do I add TWO or more please? so if test\_data has columns col1,col2,col3,col4,c…

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## [\`@nospecialize\` for variadic and keyword arguments](https://discourse.julialang.org/t/nospecialize-for-variadic-and-keyword-arguments/77517)

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**Author:** [@calebwin](https://discourse.julialang.org/u/calebwin)\
**Replies:** 3\
**Last updated:** [March 9, 2022, 9:14pm UTC](https://discourse.julialang.org/t/nospecialize-for-variadic-and-keyword-arguments/77517 "2022-03-09T21:14:20Z")

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I have a function pt: function pt( args::Union{AbstractFuture,PartitionType,PartitionTypeComposition,Vector}...; kwargs..., ) that has a whole bunch of specializations: (determined using SnoopCompile): var"#pt…

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## [What is the difference between Pkg.resolve and Pkg.instantiate?](https://discourse.julialang.org/t/what-is-the-difference-between-pkg-resolve-and-pkg-instantiate/77643)

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**Author:** [@jlapeyre](https://discourse.julialang.org/u/jlapeyre)\
**Replies:** 3\
**Last updated:** [March 9, 2022, 9:13pm UTC](https://discourse.julialang.org/t/what-is-the-difference-between-pkg-resolve-and-pkg-instantiate/77643 "2022-03-09T21:13:19Z")

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The documentation for resolve and instantiate don’t explain this thoroughly. When is Pkg.resolve useful? I notice that resolve fails if there is no registry installed. Whereas instantiate will automatically install a m…

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## [MPI.jl test\_io\_shared failing](https://discourse.julialang.org/t/mpi-jl-test-io-shared-failing/77530)

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**Author:** [@RonRahaman](https://discourse.julialang.org/u/RonRahaman)\
**Replies:** 2\
**Last updated:** [March 9, 2022, 8:02pm UTC](https://discourse.julialang.org/t/mpi-jl-test-io-shared-failing/77530 "2022-03-09T20:02:19Z")

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Hi all, I’m testing my MPI.jl build, which has been built with the cluster’s MPI library (OpenMPI 3.1.6 compiled with GCC 8.3.0). The tests (\]test MPI) succeed except for test\_io\_shared. The error message is below. I …

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## [How to find pairs of indices that meet specific criteria](https://discourse.julialang.org/t/how-to-find-pairs-of-indices-that-meet-specific-criteria/77119)

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**Author:** [@Shouto](https://discourse.julialang.org/u/Shouto)\
**Replies:** 3\
**Last updated:** [February 26, 2022, 11:18pm UTC](https://discourse.julialang.org/t/how-to-find-pairs-of-indices-that-meet-specific-criteria/77119 "2022-02-26T23:18:59Z")

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Hi all, Let E be an array such that E = \[3,5,3,5,3\] so E\[1\] = 3,…,E\[5\] = 3. I want to find and collect the pairs of two indices such that (E\[1\],E\[2\]), (E\[1\],E\[4\]),(E\[2\],E\[4\]), (E\[2\],E\[5\]), (E\[3\],E\[4\]), (E\[4\], E\[5\]). Th…

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## [How to use ElectronDisplay to display table](https://discourse.julialang.org/t/how-to-use-electrondisplay-to-display-table/77648)

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**Author:** [@realkrantz](https://discourse.julialang.org/u/realkrantz)\
**Replies:** 0\
**Last updated:** [March 9, 2022, 6:19pm UTC](https://discourse.julialang.org/t/how-to-use-electrondisplay-to-display-table/77648 "2022-03-09T18:19:44Z")

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\#This works: julia\> using VegaLite, VegaDatasets, ElectronDisplay julia\> dataset("cars") |\> @vlplot(:point, x=:Acceleration, y=:Miles\_per\_Gallon, color=:Origin) #But this does not work: julia\> using DataFrames, Elect…

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## [How \`JuMP.@expression\` will work ? / Multiple macros](https://discourse.julialang.org/t/how-jump-expression-will-work-multiple-macros/77585)

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**Author:** [@iAnkiit](https://discourse.julialang.org/u/iAnkiit)\
**Replies:** 3\
**Last updated:** [March 9, 2022, 6:06pm UTC](https://discourse.julialang.org/t/how-jump-expression-will-work-multiple-macros/77585 "2022-03-09T18:06:26Z")

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I am referring a code in which there are multiple macros with same name. So, how would it work? I mean, what attributes would be called/run when macro is called? eg. @expression(EP, ePowerBalance\[t=1:T, z=1:Z\], 0), @ex…

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## [Getting gradient of taylorinteg](https://discourse.julialang.org/t/getting-gradient-of-taylorinteg/77632)

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**Author:** [@Alseidon](https://discourse.julialang.org/u/Alseidon)\
**Replies:** 5\
**Last updated:** [March 9, 2022, 5:58pm UTC](https://discourse.julialang.org/t/getting-gradient-of-taylorinteg/77632 "2022-03-09T17:58:09Z")

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Hi, I’m quite new to Julia, and currently trying out the gradient provided by ForwardDiff.jl. I tried using it on a function that calls taylorinteg from the TaylorIntegration.jl package ; I was expecting it to give a we…

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## [Loading image using julia](https://discourse.julialang.org/t/loading-image-using-julia/76749)

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**Author:** [@randino](https://discourse.julialang.org/u/randino)\
**Replies:** 10\
**Last updated:** [March 9, 2022, 5:26pm UTC](https://discourse.julialang.org/t/loading-image-using-julia/76749 "2022-03-09T17:26:08Z")

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help me plz

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## [Is there a way to handle test case names?](https://discourse.julialang.org/t/is-there-a-way-to-handle-test-case-names/76173)

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**Author:** [@ReneUmmels](https://discourse.julialang.org/u/ReneUmmels)\
**Replies:** 5\
**Last updated:** [March 9, 2022, 5:16pm UTC](https://discourse.julialang.org/t/is-there-a-way-to-handle-test-case-names/76173 "2022-03-09T17:16:39Z")

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with @testset you can specify a set name can the same be done with @test somehow? Maybe by creating own extension for test macro, if so how? Background: Sometimes I want to have sets but also name the individual test …

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## [Urls in JuMP docs web page giving "404 error page not found"](https://discourse.julialang.org/t/urls-in-jump-docs-web-page-giving-404-error-page-not-found/77639)

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**Author:** [@harinreddy](https://discourse.julialang.org/u/harinreddy)\
**Replies:** 2\
**Last updated:** [March 9, 2022, 3:55pm UTC](https://discourse.julialang.org/t/urls-in-jump-docs-web-page-giving-404-error-page-not-found/77639 "2022-03-09T15:55:30Z")

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Hi, Some of the links in: https://github.com/jump-dev/JuMP.jl/blob/master/docs/src/index.md are throwing “404 page not found” error For example: Getting started with Julia Please let me know how to get around this …

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## [Indirect Connected vertices in a digraph](https://discourse.julialang.org/t/indirect-connected-vertices-in-a-digraph/77631)

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**Author:** [@Temi-Tory](https://discourse.julialang.org/u/Temi-Tory)\
**Replies:** 5\
**Last updated:** [March 9, 2022, 2:53pm UTC](https://discourse.julialang.org/t/indirect-connected-vertices-in-a-digraph/77631 "2022-03-09T14:53:58Z")

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Hi guys, This may be an obvious or silly question but I cannot seem to figure out how to do so. I’m not sure how to do this especially for graphs with large number of vertices, where I want to check if there is a path …

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## [Flux params restrictive](https://discourse.julialang.org/t/flux-params-restrictive/77428)

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**Author:** [@cortner](https://discourse.julialang.org/u/cortner)\
**Replies:** 9\
**Last updated:** [March 9, 2022, 2:45pm UTC](https://discourse.julialang.org/t/flux-params-restrictive/77428 "2022-03-09T14:45:01Z")

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I’m working on integrating the Zygote.Params idea into my codes to simplify parameter wrangling, and I was struck by the fact that params!(p::Params, x::AbstractArray{\<:Number}, seen = IdSet()) = push!(p, x) only array…

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## [VideoIO/GLMakie setting show\_axis for scene via plot attribute not supported anymore](https://discourse.julialang.org/t/videoio-glmakie-setting-show-axis-for-scene-via-plot-attribute-not-supported-anymore/77634)

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**Author:** [@cirobr](https://discourse.julialang.org/u/cirobr)\
**Replies:** 0\
**Last updated:** [March 9, 2022, 2:35pm UTC](https://discourse.julialang.org/t/videoio-glmakie-setting-show-axis-for-scene-via-plot-attribute-not-supported-anymore/77634 "2022-03-09T14:35:08Z")

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Cheers, A basic example code from below is giving the output error as in the title of the post. SW versions as follows: Julia 1.6.5 VideoIO 1.0.0 GLMakie 0.5.4 Example code: using GLMakie using VideoIO f = VideoIO.t…

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## [Plots.jl animation issue: dyld: Library not loaded](https://discourse.julialang.org/t/plots-jl-animation-issue-dyld-library-not-loaded/77633)

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**Author:** [@gideonsimpson](https://discourse.julialang.org/u/gideonsimpson)\
**Replies:** 0\
**Last updated:** [March 9, 2022, 2:13pm UTC](https://discourse.julialang.org/t/plots-jl-animation-issue-dyld-library-not-loaded/77633 "2022-03-09T14:13:53Z")

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I’ve started having problems with animating with Plots.jl that I previously had no issues with. For the example: using Plots @userplot CirclePlot @recipe function f(cp::CirclePlot) x, y, i = cp.args n = length…

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## [Medical segmentation framework are you intrested?](https://discourse.julialang.org/t/medical-segmentation-framework-are-you-intrested/77621)

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**Author:** [@Jakub\_Mitura](https://discourse.julialang.org/u/Jakub_Mitura)\
**Replies:** 1\
**Last updated:** [March 9, 2022, 1:33pm UTC](https://discourse.julialang.org/t/medical-segmentation-framework-are-you-intrested/77621 "2022-03-09T13:33:23Z")

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Hello I developed medical image viewer plus annotator based on OpenGL \[1\] And set of CUDA accelerated medical segmentation metrics \[2\] Currently I am working on example of using those two with some user defined CUDA.jl…

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## [Cannot install Plots on Windows 10 with Julia 1.7.2](https://discourse.julialang.org/t/cannot-install-plots-on-windows-10-with-julia-1-7-2/77624)

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**Author:** [@fredrikpaues](https://discourse.julialang.org/u/fredrikpaues)\
**Replies:** 1\
**Last updated:** [March 9, 2022, 1:27pm UTC](https://discourse.julialang.org/t/cannot-install-plots-on-windows-10-with-julia-1-7-2/77624 "2022-03-09T13:27:16Z")

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Trying to install Plots.jl and got an error ERROR: Unable to automatically install 'LERC'. These issues are killing me :sob: (@v1.7) pkg\> add Plots Resolving package versions... Downloaded artifact: LERC Download…

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## [Cannot install Arpack on Windows 10 with Julia 1.7.2](https://discourse.julialang.org/t/cannot-install-arpack-on-windows-10-with-julia-1-7-2/77625)

<div class="topic-metadata">

**Author:** [@fredrikpaues](https://discourse.julialang.org/u/fredrikpaues)\
**Replies:** 5\
**Last updated:** [March 9, 2022, 1:26pm UTC](https://discourse.julialang.org/t/cannot-install-arpack-on-windows-10-with-julia-1-7-2/77625 "2022-03-09T13:26:14Z")

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Trying to install Arpack.jl and got an error ERROR: Unable to automatically install 'Arpack'. These issues are killing me :sob: (@v1.7) pkg\> add Arpack Resolving package versions... Downloaded artifact: Arpack Do…

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## [Introducing graph computing and programming in Julia](https://discourse.julialang.org/t/introducing-graph-computing-and-programming-in-julia/77629)

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**Author:** [@Yadong\_Li](https://discourse.julialang.org/u/Yadong_Li)\
**Replies:** 0\
**Last updated:** [March 9, 2022, 11:07am UTC](https://discourse.julialang.org/t/introducing-graph-computing-and-programming-in-julia/77629 "2022-03-09T11:07:03Z")

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Dear Fellow Julia Developers: I want to share the following introductory blog on graph computing and its enormous potential. Julia is the perfect language for building generic, transparent and scalable graph computin…

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## [Solve(ode, Tsit5()) throws "Possible method error" in VS Code](https://discourse.julialang.org/t/solve-ode-tsit5-throws-possible-method-error-in-vs-code/77623)

<div class="topic-metadata">

**Author:** [@spinystellate](https://discourse.julialang.org/u/spinystellate)\
**Replies:** 4\
**Last updated:** [March 9, 2022, 11:01am UTC](https://discourse.julialang.org/t/solve-ode-tsit5-throws-possible-method-error-in-vs-code/77623 "2022-03-09T11:01:28Z")

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I am new to Julia and have started implementing my project in a Jupyter notebook. As this is not great for debugging, I have now implemented the same code in VS Code. For reasons I don’t understand, the program throws an…

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## [Makie: Mixing "spaces" while plotting](https://discourse.julialang.org/t/makie-mixing-spaces-while-plotting/77581)

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**Author:** [@marcpabst](https://discourse.julialang.org/u/marcpabst)\
**Replies:** 6\
**Last updated:** [March 9, 2022, 10:24am UTC](https://discourse.julialang.org/t/makie-mixing-spaces-while-plotting/77581 "2022-03-09T10:24:57Z")

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Hi, I have a quite simple question: Is there currently a way to plot something so that you can specify x and y coordinates in different spaces (i.e. x=10 absolute units; y=0.5 relative units w.r.t. the scene/axis height)…

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## [How to project a coordinate system on an image?](https://discourse.julialang.org/t/how-to-project-a-coordinate-system-on-an-image/77467)

<div class="topic-metadata">

**Author:** [@matic\_lauko](https://discourse.julialang.org/u/matic_lauko)\
**Replies:** 9\
**Last updated:** [March 9, 2022, 10:16am UTC](https://discourse.julialang.org/t/how-to-project-a-coordinate-system-on-an-image/77467 "2022-03-09T10:16:47Z")

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Hello, I’m trying to create a graph of some cities in Europe, I have tried guessing where cities would be but without much accuracy, and got an idea to just use an image and coordinate system to get direct coordinates an…

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## [Multiple versions of Julia on local system](https://discourse.julialang.org/t/multiple-versions-of-julia-on-local-system/77622)

<div class="topic-metadata">

**Author:** [@iAnkiit](https://discourse.julialang.org/u/iAnkiit)\
**Replies:** 4\
**Last updated:** [March 9, 2022, 9:55am UTC](https://discourse.julialang.org/t/multiple-versions-of-julia-on-local-system/77622 "2022-03-09T09:55:49Z")

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Can we use two versions of julia on local system. I am using v1.7.2 and want to install 1.3. Please guide.

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## [TaskFailedException with @threads macro with Dict](https://discourse.julialang.org/t/taskfailedexception-with-threads-macro-with-dict/77564)

<div class="topic-metadata">

**Author:** [@ekbrown](https://discourse.julialang.org/u/ekbrown)\
**Replies:** 4\
**Last updated:** [March 9, 2022, 8:06am UTC](https://discourse.julialang.org/t/taskfailedexception-with-threads-macro-with-dict/77564 "2022-03-09T08:06:27Z")

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When using Julia v1.7.2, I get a TaskFailedException when trying to use the @threads macro on a for loop over a dictionary, even though a non-threaded for loop works correctly. I lock the DataFrame that is written to. Do…

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