# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1957

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

**Page:** 1958

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## [Saving an array of complex numbers](https://discourse.julialang.org/t/saving-an-array-of-complex-numbers/23653)

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**Author:** [@M.Zahirul\_ALAM](https://discourse.julialang.org/u/M.Zahirul_ALAM)\
**Replies:** 15\
**Last updated:** [July 18, 2019, 7:09pm UTC](https://discourse.julialang.org/t/saving-an-array-of-complex-numbers/23653 "2019-07-18T19:09:00Z")

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I haven’t been using Julia for a year now. And this morning I am struggling to save a two-dimensional array of complex numbers in a file in Julia so that I can open it up in Mathematica. What is the easiest way of doing …

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## [Dependency on an un-registered fork](https://discourse.julialang.org/t/dependency-on-an-un-registered-fork/23132)

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**Author:** [@tlienart](https://discourse.julialang.org/u/tlienart)\
**Replies:** 3\
**Last updated:** [July 18, 2019, 6:59pm UTC](https://discourse.julialang.org/t/dependency-on-an-un-registered-fork/23132 "2019-07-18T18:59:06Z")

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Hello, (short) I’m contributing to a package (say B) that depends upon a unregistered patched fork (fork/A) of a registered package (A). I’d like to make sure that if a user uses B, it uses fork/A and not A if by any c…

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## [Create PDF document with PGFPlotsX figures, captions, a table, and some text](https://discourse.julialang.org/t/create-pdf-document-with-pgfplotsx-figures-captions-a-table-and-some-text/26478)

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**Author:** [@yakir12](https://discourse.julialang.org/u/yakir12)\
**Replies:** 22\
**Last updated:** [July 18, 2019, 6:56pm UTC](https://discourse.julialang.org/t/create-pdf-document-with-pgfplotsx-figures-captions-a-table-and-some-text/26478 "2019-07-18T18:56:05Z")

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I’m using PGFPlotsX to create my figures, but I want to bundle them in a report with some metadata that comes with those figures (mostly some mean-error estimates in a table and comments in a paragraph of text). I want t…

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## [Capture CMD output in Julia](https://discourse.julialang.org/t/capture-cmd-output-in-julia/26503)

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**Author:** [@Ahmed\_Salih](https://discourse.julialang.org/u/Ahmed_Salih)\
**Replies:** 2\
**Last updated:** [July 18, 2019, 3:16pm UTC](https://discourse.julialang.org/t/capture-cmd-output-in-julia/26503 "2019-07-18T15:16:47Z")

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Hey guys I am trying to use Julia in connection with CMD, so that I can do some fancy stuff. I just have a bit of starting problems, since I do not understand how to capture my cmd output. For an example let us look at …

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## [Dask and Dask-cuDF Julia alternative?](https://discourse.julialang.org/t/dask-and-dask-cudf-julia-alternative/26446)

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**Author:** [@ldsands](https://discourse.julialang.org/u/ldsands)\
**Replies:** 8\
**Last updated:** [July 18, 2019, 3:03pm UTC](https://discourse.julialang.org/t/dask-and-dask-cudf-julia-alternative/26446 "2019-07-18T15:03:04Z")

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Hello everyone, TLDR: looking for information on Julia’s Dask and Dask-cuDF alternatives I’m having to analyze some data for my social science degree and it is very large. I’m using python, pandas and dask to parrellel…

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## [How to do it remake](https://discourse.julialang.org/t/how-to-do-it-remake/26500)

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**Author:** [@1112](https://discourse.julialang.org/u/1112)\
**Replies:** 2\
**Last updated:** [July 18, 2019, 2:06pm UTC](https://discourse.julialang.org/t/how-to-do-it-remake/26500 "2019-07-18T14:06:55Z")

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IssetX = function(ArX,x) indexX = true try indexX = getindex(ArX, x) catch indexX = false end indexX end ArX = Dict(542=\>1,566=\>2) IssetX(ArX,550) x may not be in ArX, I just make an exception, maybe…

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## [Chaostools tangent\_integrator stiff solvers](https://discourse.julialang.org/t/chaostools-tangent-integrator-stiff-solvers/26464)

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**Author:** [@jamblejoe](https://discourse.julialang.org/u/jamblejoe)\
**Replies:** 27\
**Last updated:** [July 18, 2019, 1:21pm UTC](https://discourse.julialang.org/t/chaostools-tangent-integrator-stiff-solvers/26464 "2019-07-18T13:21:34Z")

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Hi, I want to use the tangent\_integrator function from the ChaosTools package with solvers for stiff problems: integ = tangent\_integrator(cds, w0; alg=Rodas5(), abstol=1e-9, reltol=1e-9) step!(integ, 1.0) but this giv…

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## [Pkg3 problems, trying to clean up](https://discourse.julialang.org/t/pkg3-problems-trying-to-clean-up/26497)

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**Author:** [@tamasgal](https://discourse.julialang.org/u/tamasgal)\
**Replies:** 7\
**Last updated:** [July 18, 2019, 1:11pm UTC](https://discourse.julialang.org/t/pkg3-problems-trying-to-clean-up/26497 "2019-07-18T13:11:54Z")

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I don’t understand the following: I had a package in a project in dev mode and now I wanted to change that out to an official release. Doing an rm and then an add simply did not work as Julia somehow memoized that I am u…

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## [Help me structure my code and extend it to a working example: Using DiffEqFlux to interpolate GDP data and see if there is a singularity](https://discourse.julialang.org/t/help-me-structure-my-code-and-extend-it-to-a-working-example-using-diffeqflux-to-interpolate-gdp-data-and-see-if-there-is-a-singularity/26487)

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**Author:** [@freemint](https://discourse.julialang.org/u/freemint)\
**Replies:** 2\
**Last updated:** [July 18, 2019, 11:52am UTC](https://discourse.julialang.org/t/help-me-structure-my-code-and-extend-it-to-a-working-example-using-diffeqflux-to-interpolate-gdp-data-and-see-if-there-is-a-singularity/26487 "2019-07-18T11:52:46Z")

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Hello, i tried to solve my own toy problem for DiffEqFlux since i found the example that comes with DiffEqFlux confusing. The source is available here, frankly it is in a messy shape right now: GitHub - freemin7/GDPPr-…

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## [Segmentation fault trying to Fezzik.brute\_build\_julia() on: using Blink; w = Window()](https://discourse.julialang.org/t/segmentation-fault-trying-to-fezzik-brute-build-julia-on-using-blink-w-window/26491)

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**Author:** [@KestutisMa](https://discourse.julialang.org/u/KestutisMa)\
**Replies:** 1\
**Last updated:** [July 18, 2019, 11:47am UTC](https://discourse.julialang.org/t/segmentation-fault-trying-to-fezzik-brute-build-julia-on-using-blink-w-window/26491 "2019-07-18T11:47:04Z")

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Hi, I am trying to speed-up compilation of packages, PackageCompiler works nice, but current version uses all statements from package’s runtests.jl for creating precompiles. I think compiling only functions that I freque…

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## [Printing user defined unsigned primitive typed](https://discourse.julialang.org/t/printing-user-defined-unsigned-primitive-typed/26467)

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**Author:** [@hros](https://discourse.julialang.org/u/hros)\
**Replies:** 3\
**Last updated:** [July 18, 2019, 11:28am UTC](https://discourse.julialang.org/t/printing-user-defined-unsigned-primitive-typed/26467 "2019-07-18T11:28:01Z")

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Following the advice in this post I declared a user defined primitive type of 32 bits. This works when declared as a signed 32 bit integer: abstract type MyType \<: Signed end primitive type MyType32 \<: MyType 32 end My…

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## [Modules VS Passing arguments to functions](https://discourse.julialang.org/t/modules-vs-passing-arguments-to-functions/26477)

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**Author:** [@tiago](https://discourse.julialang.org/u/tiago)\
**Replies:** 5\
**Last updated:** [July 18, 2019, 11:03am UTC](https://discourse.julialang.org/t/modules-vs-passing-arguments-to-functions/26477 "2019-07-18T11:03:39Z")

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Hello, I developed a numerical solver for a certain PDE. In these situations it’s quite normal to test the algorithm with several different examples and have many parameters, arrays and anonymous functions that I must …

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## [Way to "encode" an object?](https://discourse.julialang.org/t/way-to-encode-an-object/26465)

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**Author:** [@tomtom](https://discourse.julialang.org/u/tomtom)\
**Replies:** 8\
**Last updated:** [July 18, 2019, 8:35am UTC](https://discourse.julialang.org/t/way-to-encode-an-object/26465 "2019-07-18T08:35:18Z")

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I have some user-defined types where the object could not be saved by JLD or JLD2. I’m wondering if there’s some way to “encode” an arbitrary object into a string, which I can then later “parse” (or “decode”) the string…

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## [Indices in file names?](https://discourse.julialang.org/t/indices-in-file-names/26376)

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**Author:** [@MuadhF](https://discourse.julialang.org/u/MuadhF)\
**Replies:** 16\
**Last updated:** [July 18, 2019, 7:51am UTC](https://discourse.julialang.org/t/indices-in-file-names/26376 "2019-07-18T07:51:32Z")

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Hi, If I’m sending data to a CSV file in a for loop function, this means that I would need multiple files for each run, but how do I ensure that the file names would be different so that overwriting is avoided? I though…

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## [Interactive plot, acting as a range slider tool for another plot?](https://discourse.julialang.org/t/interactive-plot-acting-as-a-range-slider-tool-for-another-plot/20392)

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**Author:** [@sairus7](https://discourse.julialang.org/u/sairus7)\
**Replies:** 18\
**Last updated:** [July 18, 2019, 7:34am UTC](https://discourse.julialang.org/t/interactive-plot-acting-as-a-range-slider-tool-for-another-plot/20392 "2019-07-18T07:34:27Z")

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How can I get in Julia an interactive plot with range slider for another plot? Something like this (but not necessary with the same data on both plots): https://bokeh.pydata.org/en/latest/docs/gallery/range\_tool.html …

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## [How to change font size in Plots.jl](https://discourse.julialang.org/t/how-to-change-font-size-in-plots-jl/18401)

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**Author:** [@Gregory\_Martinez](https://discourse.julialang.org/u/Gregory_Martinez)\
**Replies:** 1\
**Last updated:** [July 18, 2019, 3:04am UTC](https://discourse.julialang.org/t/how-to-change-font-size-in-plots-jl/18401 "2019-07-18T03:04:10Z")

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So, I’m trying to change the font size using Plots.jl for outputed graphs, but whatever option I use, nothing changes. I’m trying using Plots plot(flux, yscale=:log10, xlabel="wavelegth", ylabel="flux", xtickf…

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## [Fast Robust Predicates for Computational Geometry: Something in Julia?](https://discourse.julialang.org/t/fast-robust-predicates-for-computational-geometry-something-in-julia/5807)

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**Author:** [@Datseris](https://discourse.julialang.org/u/Datseris)\
**Replies:** 6\
**Last updated:** [July 18, 2019, 1:25am UTC](https://discourse.julialang.org/t/fast-robust-predicates-for-computational-geometry-something-in-julia/5807 "2019-07-18T01:25:49Z")

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Hello all, I am doing a lot of computations for a package (DynamicalBilliards.jl) where I very often compute dot products, differences, multiplications and sums of floating point numbers that are very small (order of 1e…

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## [CSP examples in Julia?](https://discourse.julialang.org/t/csp-examples-in-julia/20011)

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**Author:** [@NHDaly](https://discourse.julialang.org/u/NHDaly)\
**Replies:** 2\
**Last updated:** [July 18, 2019, 12:13am UTC](https://discourse.julialang.org/t/csp-examples-in-julia/20011 "2019-07-18T00:13:57Z")

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Golang’s concurrency primitives were originally inspired by C. A. R. Hoare’s famous 1978 paper “Communicating sequential processes”, (paper, book). Here’s a blog post where they talk about it: This git repo re-implem…

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## [Problems with Diagonal from LinearAlgebra](https://discourse.julialang.org/t/problems-with-diagonal-from-linearalgebra/26429)

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**Author:** [@cholt](https://discourse.julialang.org/u/cholt)\
**Replies:** 11\
**Last updated:** [July 17, 2019, 7:55pm UTC](https://discourse.julialang.org/t/problems-with-diagonal-from-linearalgebra/26429 "2019-07-17T19:55:06Z")

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I have been using the Diagonal function to take a vector array and produce a matrix with entries of the vector along the diagonal. It used to work fine but now instead of producing a matrix with entries along the diagona…

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## [Bumping \`Project.toml\` version number after tag](https://discourse.julialang.org/t/bumping-project-toml-version-number-after-tag/26471)

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**Author:** [@ExpandingMan](https://discourse.julialang.org/u/ExpandingMan)\
**Replies:** 8\
**Last updated:** [July 17, 2019, 7:27pm UTC](https://discourse.julialang.org/t/bumping-project-toml-version-number-after-tag/26471 "2019-07-17T19:27:55Z")

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This is a really trivial thing, but I’ve yet to find a really good workflow for it. I always forget to go into my Project.toml and bump the version number of my package after I make a tag. Worse, sometimes I make a tag…

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## [Pre-allocating output array for ArrayFire.jl function](https://discourse.julialang.org/t/pre-allocating-output-array-for-arrayfire-jl-function/26472)

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**Author:** [@Josiah\_Slack](https://discourse.julialang.org/u/Josiah_Slack)\
**Replies:** 2\
**Last updated:** [July 17, 2019, 7:04pm UTC](https://discourse.julialang.org/t/pre-allocating-output-array-for-arrayfire-jl-function/26472 "2019-07-17T19:04:30Z")

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I have a use case where it would helpful if I could allocate a cuda array prior to calling, say cholesky(), which would then be filled by the called function. Is there a straightforward way of doing this?

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## [ForwardDiff - Multiple gradient evaluations at once?](https://discourse.julialang.org/t/forwarddiff-multiple-gradient-evaluations-at-once/26473)

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**Author:** [@LudiWin](https://discourse.julialang.org/u/LudiWin)\
**Replies:** 8\
**Last updated:** [July 17, 2019, 6:59pm UTC](https://discourse.julialang.org/t/forwarddiff-multiple-gradient-evaluations-at-once/26473 "2019-07-17T18:59:20Z")

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Hi, so I’m fairly new to Julia coming from Python. I was playing around with the ForwardDiff package and stumbled upon the following ‘problem’: A 2-D Gaussian from the Distributions package can take a matrix of size =…

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## [Can I get variable value during the optimization JuMP.value?](https://discourse.julialang.org/t/can-i-get-variable-value-during-the-optimization-jump-value/26474)

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**Author:** [@faoh](https://discourse.julialang.org/u/faoh)\
**Replies:** 2\
**Last updated:** [July 17, 2019, 6:50pm UTC](https://discourse.julialang.org/t/can-i-get-variable-value-during-the-optimization-jump-value/26474 "2019-07-17T18:50:55Z")

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I want to get variables’ value and use it in objective function during the optimization. When I try JuMP.value(), it shows NoOptimizer(). But the Optimizer is defined in the main function. Is there anyway that I can ge…

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## [How to edit row values of a dataframe column based on condition using query.jl](https://discourse.julialang.org/t/how-to-edit-row-values-of-a-dataframe-column-based-on-condition-using-query-jl/26437)

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**Author:** [@vivekraj](https://discourse.julialang.org/u/vivekraj)\
**Replies:** 7\
**Last updated:** [July 17, 2019, 6:47pm UTC](https://discourse.julialang.org/t/how-to-edit-row-values-of-a-dataframe-column-based-on-condition-using-query-jl/26437 "2019-07-17T18:47:30Z")

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i have filtered unique values from a column :CarCompany from dataframe: df |\> @map(\_.CarCompany) |\> @unique() |\> collect; the output shows fields with spelling mistakes: 28-element Array{SubString{String},1}: “alfa-r…

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## [CSV ruins scientific notation](https://discourse.julialang.org/t/csv-ruins-scientific-notation/25835)

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**Author:** [@Wikunia](https://discourse.julialang.org/u/Wikunia)\
**Replies:** 10\
**Last updated:** [July 17, 2019, 5:52pm UTC](https://discourse.julialang.org/t/csv-ruins-scientific-notation/25835 "2019-07-17T17:52:41Z")

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I think it’s a bug in CSV but I’m not 100% sure that’s why I ask here first: I wrote some code to convert a txt file into a csv file (basically adding a header and commata). My code: fname = input\_name = split(split(t…

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## [New behaviour due to an update of the package CSV when using CSV.write](https://discourse.julialang.org/t/new-behaviour-due-to-an-update-of-the-package-csv-when-using-csv-write/26442)

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**Author:** [@steph\_de\_paris](https://discourse.julialang.org/u/steph_de_paris)\
**Replies:** 7\
**Last updated:** [July 17, 2019, 1:02pm UTC](https://discourse.julialang.org/t/new-behaviour-due-to-an-update-of-the-package-csv-when-using-csv-write/26442 "2019-07-17T13:02:29Z")

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Hello, When I use the code using CSV using DataFrames rm("tmp.csv",force=true) df=DataFrame(\[Float64 for k in 1:1\],\[Symbol("ps\_prev\_$k") for k in 1:1\],0); push!(df,1000.0) CSV.write("tmp.csv",df,delim=';', append=true,…

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## [Error: The applicable method may be too new: running in world age 25634, while current world is 25663](https://discourse.julialang.org/t/error-the-applicable-method-may-be-too-new-running-in-world-age-25634-while-current-world-is-25663/26445)

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**Author:** [@apattyn](https://discourse.julialang.org/u/apattyn)\
**Replies:** 10\
**Last updated:** [July 17, 2019, 5:20pm UTC](https://discourse.julialang.org/t/error-the-applicable-method-may-be-too-new-running-in-world-age-25634-while-current-world-is-25663/26445 "2019-07-17T17:20:26Z")

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Specs: $ julia \_ \_ \_ \_(\_)\_ | Documentation: https://docs.julialang.org (\_) | (\_) (\_) | \_ \_ \_| |\_ \_\_ \_ | Type "?" for help, "\]?" for Pkg help. | | | | | | |/ \_\` | | | |…

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## [How to solve large sparse LPs in Gurobi](https://discourse.julialang.org/t/how-to-solve-large-sparse-lps-in-gurobi/26402)

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**Author:** [@wenqi\_kou](https://discourse.julialang.org/u/wenqi_kou)\
**Replies:** 7\
**Last updated:** [July 17, 2019, 5:20pm UTC](https://discourse.julialang.org/t/how-to-solve-large-sparse-lps-in-gurobi/26402 "2019-07-17T17:20:00Z")

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Hi, I have a question about solving large sparse matrix LP problem. It really confused me for a long time. If I have a form like this: I have all Fi data, which are in sparse form. How can I build a LP model to solv…

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## [AD step for iterative solution](https://discourse.julialang.org/t/ad-step-for-iterative-solution/26404)

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**Author:** [@Tamas\_Papp](https://discourse.julialang.org/u/Tamas_Papp)\
**Replies:** 11\
**Last updated:** [July 17, 2019, 4:09pm UTC](https://discourse.julialang.org/t/ad-step-for-iterative-solution/26404 "2019-07-17T16:09:48Z")

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Sometimes it would be useful to AD through an iterative algorithm, eg solving a parametric problem f(x, a) = 0 which implicitly defines x(a), but in practice uses an iterative rootfinding method. The math is clear (i…

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## [Strange allocation](https://discourse.julialang.org/t/strange-allocation/26462)

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**Author:** [@TheBB](https://discourse.julialang.org/u/TheBB)\
**Replies:** 2\
**Last updated:** [July 17, 2019, 3:31pm UTC](https://discourse.julialang.org/t/strange-allocation/26462 "2019-07-17T15:31:37Z")

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I’m writing a type to represent an affine transformation (y=Ax+b), using static arrays. Here’s the code using BenchmarkTools using StaticArrays struct Affine{F, T, R} matrix :: SMatrix{T, F, R} vector :: SVecto…

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