# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=547

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**Page:** 548

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## [Custom formatter for a DataFrame column?](https://discourse.julialang.org/t/custom-formatter-for-a-dataframe-column/7777)

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**Author:** [@airpmb](https://discourse.julialang.org/u/airpmb)\
**Replies:** 1\
**Last updated:** [December 15, 2017, 8:57am UTC](https://discourse.julialang.org/t/custom-formatter-for-a-dataframe-column/7777 "2017-12-15T08:57:31Z")

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Is there a good way to customize the formatting of the values in particular columns of a DataFrame? I have a column that is using the types from Currencies.jl, which have great functionality but their default display for…

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## [Problem with ForwardDiff and pre-allocating vector](https://discourse.julialang.org/t/problem-with-forwarddiff-and-pre-allocating-vector/7741)

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**Author:** [@jacobcvt12](https://discourse.julialang.org/u/jacobcvt12)\
**Replies:** 6\
**Last updated:** [December 14, 2017, 8:37pm UTC](https://discourse.julialang.org/t/problem-with-forwarddiff-and-pre-allocating-vector/7741 "2017-12-14T20:37:42Z")

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I’m attempting to use ForwardDiff in a function that involves several instances of pre-allocating vectors. I’ve boiled the function down to the cause of the bug using ForwardDiff function f(x) tmp = zeros(2) …

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## [Problem with changing color map inside plot recipe](https://discourse.julialang.org/t/problem-with-changing-color-map-inside-plot-recipe/7756)

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**Author:** [@juliohm](https://discourse.julialang.org/u/juliohm)\
**Replies:** 2\
**Last updated:** [December 14, 2017, 4:36pm UTC](https://discourse.julialang.org/t/problem-with-changing-color-map-inside-plot-recipe/7756 "2017-12-14T16:36:36Z")

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Consider the following plot recipe: using RecipesBase struct DummyType end @recipe function f(dummy::DummyType) @series begin seriestype := :contourf color --\> :bluesreds \[i+j for …

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## [What is the future of time-indexed dataframes?](https://discourse.julialang.org/t/what-is-the-future-of-time-indexed-dataframes/7751)

<div class="topic-metadata">

**Author:** [@juliohm](https://discourse.julialang.org/u/juliohm)\
**Replies:** 3\
**Last updated:** [December 14, 2017, 12:39am UTC](https://discourse.julialang.org/t/what-is-the-future-of-time-indexed-dataframes/7751 "2017-12-14T00:39:49Z")

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After some research today, I came across this thread discussing the pros and cons of different approaches for handling time series data in dataframe-like format: https://github.com/JuliaStats/Roadmap.jl/issues/10 Can yo…

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## [Converting missing type into float](https://discourse.julialang.org/t/converting-missing-type-into-float/7740)

<div class="topic-metadata">

**Author:** [@Fred](https://discourse.julialang.org/u/Fred)\
**Replies:** 5\
**Last updated:** [December 13, 2017, 3:45pm UTC](https://discourse.julialang.org/t/converting-missing-type-into-float/7740 "2017-12-13T15:45:14Z")

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Hi, The new “missing” type introduced in DataFrames is a source of many errors in all the Julia programs I have made previously and I would like to find a way to remove this missing type. For example the competerank() …

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## [CSV problem reading empty string column](https://discourse.julialang.org/t/csv-problem-reading-empty-string-column/7710)

<div class="topic-metadata">

**Author:** [@Daneel](https://discourse.julialang.org/u/Daneel)\
**Replies:** 2\
**Last updated:** [December 13, 2017, 8:56am UTC](https://discourse.julialang.org/t/csv-problem-reading-empty-string-column/7710 "2017-12-13T08:56:23Z")

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How can I read a text data file with an empty string column? The file rarely, if ever, has a string in the column. data.dat 12/10/2016 00:00:00 0.004 3564172800.000 23:00:00 SPEC:NH3 time, Range\_F 1\_L 1, Zero\_F 1, Rang…

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## [Why Don't Shared Arrays Allow Non-Bit-Types?](https://discourse.julialang.org/t/why-dont-shared-arrays-allow-non-bit-types/6975)

<div class="topic-metadata">

**Author:** [@Juser](https://discourse.julialang.org/u/Juser)\
**Replies:** 5\
**Last updated:** [December 12, 2017, 7:23pm UTC](https://discourse.julialang.org/t/why-dont-shared-arrays-allow-non-bit-types/6975 "2017-12-12T19:23:43Z")

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It would be extremely useful to have shared arrays of non-bit-types. Automatic differentiation, for example, requires functions to accept \<:Real types, and this makes shared arrays difficult to use within function evalu…

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## [JuMP: Ipopt, ECOS, ErrorMsg: no method matching setvartype](https://discourse.julialang.org/t/jump-ipopt-ecos-errormsg-no-method-matching-setvartype/7705)

<div class="topic-metadata">

**Author:** [@Anton\_Hinneck](https://discourse.julialang.org/u/Anton_Hinneck)\
**Replies:** 3\
**Last updated:** [December 12, 2017, 5:31pm UTC](https://discourse.julialang.org/t/jump-ipopt-ecos-errormsg-no-method-matching-setvartype/7705 "2017-12-12T17:31:08Z")

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Hi, I have been programming a MILP for university. The model is feasible and was already solved using GLPK, CBC, Gurobi and CPLEX. The results are as expected and were carefully examined already. However, I have an issue…

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## [Knet.jl CNN Tutorial Speed](https://discourse.julialang.org/t/knet-jl-cnn-tutorial-speed/7500)

<div class="topic-metadata">

**Author:** [@rickhg12hs](https://discourse.julialang.org/u/rickhg12hs)\
**Replies:** 3\
**Last updated:** [December 12, 2017, 1:59pm UTC](https://discourse.julialang.org/t/knet-jl-cnn-tutorial-speed/7500 "2017-12-12T13:59:43Z")

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Knet’s tutorial.ipynb trains a CNN with MNIST data. I have no GPU, but my quad-core I7 has been pegged for a day stuck on cnnmodels = \[ copy(train!(wcnn, dtrn)) for epoch=1:100 \];. Is this exceptionally long training t…

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## [First-class histogram object and plotting in Plots.jl](https://discourse.julialang.org/t/first-class-histogram-object-and-plotting-in-plots-jl/7674)

<div class="topic-metadata">

**Author:** [@Tamas\_Papp](https://discourse.julialang.org/u/Tamas_Papp)\
**Replies:** 2\
**Last updated:** [December 11, 2017, 7:33am UTC](https://discourse.julialang.org/t/first-class-histogram-object-and-plotting-in-plots-jl/7674 "2017-12-11T07:33:22Z")

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I have a dataset with a large number of points, and would like to plot histograms which are costly to calculate. I would prefer if I could save the calculated histogram using JLD2, then load it in a separate script for p…

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## [Range for core function rand()](https://discourse.julialang.org/t/range-for-core-function-rand/7685)

<div class="topic-metadata">

**Author:** [@zlon](https://discourse.julialang.org/u/zlon)\
**Replies:** 1\
**Last updated:** [December 10, 2017, 10:01pm UTC](https://discourse.julialang.org/t/range-for-core-function-rand/7685 "2017-12-10T22:01:23Z")

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I couldn’t find it in docs. If X=rand(), then X comes from \[0 1\] or \[0 1) or some other variance?

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## [Set Cache Configuration using CUDAdrv or CUDAnative](https://discourse.julialang.org/t/set-cache-configuration-using-cudadrv-or-cudanative/7675)

<div class="topic-metadata">

**Author:** [@drjoke](https://discourse.julialang.org/u/drjoke)\
**Replies:** 1\
**Last updated:** [December 10, 2017, 5:38pm UTC](https://discourse.julialang.org/t/set-cache-configuration-using-cudadrv-or-cudanative/7675 "2017-12-10T17:38:20Z")

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Similar to cudaFuncSetCacheConfig(fooKernel, cudaFuncCachePreferL1) I cannot find any example on how to do this. Is it possible?

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## [Deprecated csv prefix](https://discourse.julialang.org/t/deprecated-csv-prefix/7616)

<div class="topic-metadata">

**Author:** [@juliohm](https://discourse.julialang.org/u/juliohm)\
**Replies:** 4\
**Last updated:** [December 8, 2017, 10:22pm UTC](https://discourse.julialang.org/t/deprecated-csv-prefix/7616 "2017-12-08T22:22:19Z")

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Hi, Can you please clarify the newer syntax? csv""" x, y, z 1, 2, 3 """ @csv\_str and the csv"“” syntax are deprecated. Use CSV.read(IOBuffer(…)) from the CSV package instead. Why the csv prefix was deprecated, coul…

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## [Review of presentation](https://discourse.julialang.org/t/review-of-presentation/7615)

<div class="topic-metadata">

**Author:** [@xiaodai](https://discourse.julialang.org/u/xiaodai)\
**Replies:** 12\
**Last updated:** [December 8, 2017, 9:00pm UTC](https://discourse.julialang.org/t/review-of-presentation/7615 "2017-12-08T21:00:54Z")

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I made this presentation focused on the data ecosystem in Julia. I just wanted to post it here for feedback so I can polish it. Thanks

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## [Interpolation in constraint](https://discourse.julialang.org/t/interpolation-in-constraint/7325)

<div class="topic-metadata">

**Author:** [@MaximilianJHuber](https://discourse.julialang.org/u/MaximilianJHuber)\
**Replies:** 3\
**Last updated:** [December 7, 2017, 3:59pm UTC](https://discourse.julialang.org/t/interpolation-in-constraint/7325 "2017-12-07T15:59:17Z")

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Hi, I have a conceptional question: I have 10 non-linear constraints for k=k\_1, ..., k\_{10} (that represent a discrete grid of a continuous variable) and 10 coefficients, \\theta = \\theta\_1, ... \\theta\_{10}, that are det…

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## [Memory corruption bugs in ECOS.jl and SCS.jl](https://discourse.julialang.org/t/memory-corruption-bugs-in-ecos-jl-and-scs-jl/7582)

<div class="topic-metadata">

**Author:** [@miles.lubin](https://discourse.julialang.org/u/miles.lubin)\
**Replies:** 0\
**Last updated:** [December 6, 2017, 10:26pm UTC](https://discourse.julialang.org/t/memory-corruption-bugs-in-ecos-jl-and-scs-jl/7582 "2017-12-06T22:26:50Z")

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We recently discovered and corrected memory corruption bugs in both ECOS.jl and SCS.jl. The wrappers did not properly keep a reference in Julia to the memory passed to the solvers, so if the GC fired at an inopportune t…

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## [Sorting seems to have some low hanging speed fruit for sorting by single column](https://discourse.julialang.org/t/sorting-seems-to-have-some-low-hanging-speed-fruit-for-sorting-by-single-column/7568)

<div class="topic-metadata">

**Author:** [@xiaodai](https://discourse.julialang.org/u/xiaodai)\
**Replies:** 7\
**Last updated:** [December 6, 2017, 10:21pm UTC](https://discourse.julialang.org/t/sorting-seems-to-have-some-low-hanging-speed-fruit-for-sorting-by-single-column/7568 "2017-12-06T22:21:31Z")

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I was doing some benchmarking of data.table vs DataFrames.jl. Of course, data.table is still way faster on sorting. But I found a low hanging fruit for sorting performance; it could be the backbone of a PR. Here is an MW…

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## [DifferentialEquations.jl: split differential equation with explicit propagators](https://discourse.julialang.org/t/differentialequations-jl-split-differential-equation-with-explicit-propagators/7572)

<div class="topic-metadata">

**Author:** [@antoine-levitt](https://discourse.julialang.org/u/antoine-levitt)\
**Replies:** 3\
**Last updated:** [December 6, 2017, 7:45pm UTC](https://discourse.julialang.org/t/differentialequations-jl-split-differential-equation-with-explicit-propagators/7572 "2017-12-06T19:45:03Z")

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I have a PDE that is (not exactly but close to) du/dt + v \\cdot du/dx = A(x)u, where x is 2D, u is a vector with two components and A is a 2x2 matrix. The initial data possibly has shocks (discontinuities). Right now I u…

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## [@parallel for and more complex operations](https://discourse.julialang.org/t/parallel-for-and-more-complex-operations/7562)

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**Author:** [@Ferran\_Mazzanti](https://discourse.julialang.org/u/Ferran_Mazzanti)\
**Replies:** 8\
**Last updated:** [December 6, 2017, 6:12pm UTC](https://discourse.julialang.org/t/parallel-for-and-more-complex-operations/7562 "2017-12-06T18:12:38Z")

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Hi, I’m starting to appreciate the benefits and simplicity of @parallel for in my codes… sometimes these really run fast, but I have seen that the operation you can perform on the result of each iteration in the for is …

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## [Restarting NLP solve from previous infeasible solution](https://discourse.julialang.org/t/restarting-nlp-solve-from-previous-infeasible-solution/7542)

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**Author:** [@adowling2](https://discourse.julialang.org/u/adowling2)\
**Replies:** 1\
**Last updated:** [December 6, 2017, 2:25am UTC](https://discourse.julialang.org/t/restarting-nlp-solve-from-previous-infeasible-solution/7542 "2017-12-06T02:25:13Z")

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I am solving a nasty, non-convex NLP. In some instances, Ipopt converges to a point of local infeasibility. For other problems, I observed that restarting Ipopt from such an infeasible solution can sometimes lead to an o…

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## [Symv producing incorrect results](https://discourse.julialang.org/t/symv-producing-incorrect-results/7548)

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**Author:** [@Elrod](https://discourse.julialang.org/u/Elrod)\
**Replies:** 2\
**Last updated:** [December 5, 2017, 10:02pm UTC](https://discourse.julialang.org/t/symv-producing-incorrect-results/7548 "2017-12-05T22:02:56Z")

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Can anyone reproduce the following bug? julia\> A = randn(10,20) |\> X -\> X \* X'; julia\> x = rand(10); julia\> sA = Symmetric(A); julia\> all( A .== sA ) true julia\> (A \* x)' 1×10 RowVector{Float64,Array{Float64,1}}: 1…

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## [Introducing a new Control Toolbox for Julia with Interactive root locus](https://discourse.julialang.org/t/introducing-a-new-control-toolbox-for-julia-with-interactive-root-locus/7486)

<div class="topic-metadata">

**Author:** [@Ronis\_BR](https://discourse.julialang.org/u/Ronis_BR)\
**Replies:** 13\
**Last updated:** [December 5, 2017, 12:45pm UTC](https://discourse.julialang.org/t/introducing-a-new-control-toolbox-for-julia-with-interactive-root-locus/7486 "2017-12-05T12:45:12Z")

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Hi guys! I finally decided to publish a Control Toolbox we were developing at my institution. I know that there are a few alternatives already coded in Julia, but we wanted something more specific. We wanted that the co…

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## [Incorrect Bound Error Exception](https://discourse.julialang.org/t/incorrect-bound-error-exception/7525)

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**Author:** [@tlagos](https://discourse.julialang.org/u/tlagos)\
**Replies:** 1\
**Last updated:** [December 5, 2017, 12:11pm UTC](https://discourse.julialang.org/t/incorrect-bound-error-exception/7525 "2017-12-05T12:11:24Z")

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Hello, I’m doing a enumeration of solutions in a simulation framework. As an example, I’m consulting if the k-th component in the t-th period was already visited: sum(wx\[k,1:t\])==0 The weird thing is that is throwing…

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## [Plot(twinx(), ...) creates ylabel on the wrong side of the plot (left instead of ríght)](https://discourse.julialang.org/t/plot-twinx-creates-ylabel-on-the-wrong-side-of-the-plot-left-instead-of-right/7437)

<div class="topic-metadata">

**Author:** [@LotteVictor](https://discourse.julialang.org/u/LotteVictor)\
**Replies:** 3\
**Last updated:** [December 4, 2017, 8:53am UTC](https://discourse.julialang.org/t/plot-twinx-creates-ylabel-on-the-wrong-side-of-the-plot-left-instead-of-right/7437 "2017-12-04T08:53:13Z")

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Hey all! I hope, I’m posting this in the correct category. In my question about visualization (Overlay plot with second plot with second y-axis to the right?) an issue occured that was identified as a bug by @mkborregaar…

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## [Plots: Past, Present, and Future](https://discourse.julialang.org/t/plots-past-present-and-future/7469)

<div class="topic-metadata">

**Author:** [@tbreloff](https://discourse.julialang.org/u/tbreloff)\
**Replies:** 2\
**Last updated:** [December 3, 2017, 3:57pm UTC](https://discourse.julialang.org/t/plots-past-present-and-future/7469 "2017-12-03T15:57:01Z")

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Hi all. I’ve been very passively monitoring activity in the Julia community the last few months, and I’ve noticed some confusion about Plots/JuliaPlots as well as my role in the community. I’ve been meaning to post som…

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## [TensorFlow.jl MNIST Tutorial fails.](https://discourse.julialang.org/t/tensorflow-jl-mnist-tutorial-fails/7476)

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**Author:** [@rickhg12hs](https://discourse.julialang.org/u/rickhg12hs)\
**Replies:** 0\
**Last updated:** [December 3, 2017, 2:30pm UTC](https://discourse.julialang.org/t/tensorflow-jl-mnist-tutorial-fails/7476 "2017-12-03T14:30:44Z")

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Ref: Github Issue Report Both MNIST tutorials (softmax & CNN) fail with TensorFlow.jl. I’m a ML noob and I’m not sure how to further diagnose the problem. Is this a Tensorflow.jl problem or perhaps a tutorial problem? …

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## [When shall I use \`BLAS.axpy!\` and when \`muladd\`?](https://discourse.julialang.org/t/when-shall-i-use-blas-axpy-and-when-muladd/7466)

<div class="topic-metadata">

**Author:** [@chobbes](https://discourse.julialang.org/u/chobbes)\
**Replies:** 6\
**Last updated:** [December 3, 2017, 2:22pm UTC](https://discourse.julialang.org/t/when-shall-i-use-blas-axpy-and-when-muladd/7466 "2017-12-03T14:22:03Z")

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Can’t tell much difference between the two. Any insights? Thanks.

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## [Loading/writing a single element from an array in JLD](https://discourse.julialang.org/t/loading-writing-a-single-element-from-an-array-in-jld/7414)

<div class="topic-metadata">

**Author:** [@Axel\_Gagge](https://discourse.julialang.org/u/Axel_Gagge)\
**Replies:** 3\
**Last updated:** [December 3, 2017, 3:07am UTC](https://discourse.julialang.org/t/loading-writing-a-single-element-from-an-array-in-jld/7414 "2017-12-03T03:07:56Z")

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I want to save and load data with JLD.jl (or HDF5.jl or something) which is is a 1-dimensional array of large elements (themselves large arrays). I want to be able to work with one or a few of the array elements at a tim…

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## [@parallel constructs](https://discourse.julialang.org/t/parallel-constructs/7460)

<div class="topic-metadata">

**Author:** [@TomConlin](https://discourse.julialang.org/u/TomConlin)\
**Replies:** 4\
**Last updated:** [December 2, 2017, 11:33pm UTC](https://discourse.julialang.org/t/parallel-constructs/7460 "2017-12-02T23:33:30Z")

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Hope this is the appropriate place to put this, if not please feel free to move it. I am wondering if Julia would accept a PR for additional @parallel macros optimized for Lower (and Upper) Triangular Matrices. The b…

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## [Accurate summation algorithm](https://discourse.julialang.org/t/accurate-summation-algorithm/7163)

<div class="topic-metadata">

**Author:** [@certik](https://discourse.julialang.org/u/certik)\
**Replies:** 34\
**Last updated:** [December 1, 2017, 7:45pm UTC](https://discourse.julialang.org/t/accurate-summation-algorithm/7163 "2017-12-01T19:45:05Z")

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Stefan Karpinski posted an interesting challenge in https://github.com/JuliaLang/julia/issues/24568#issuecomment-344760163: Try to find a summation algorithm whose results are always between (1-1e-14)\*s and (1+1e-14)\*s…

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