# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=536

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**Page:** 537

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## [Basic Task Cooperation with Locks](https://discourse.julialang.org/t/basic-task-cooperation-with-locks/11186)

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**Author:** [@iwelch](https://discourse.julialang.org/u/iwelch)\
**Replies:** 0\
**Last updated:** [May 27, 2018, 6:36pm UTC](https://discourse.julialang.org/t/basic-task-cooperation-with-locks/11186 "2018-05-27T18:36:18Z")

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Dear Julia wizards: I understand that parallelism is still a work in progress, but I would like to know how to sketch the following code. My code wants to maintain a shared (int) vector of what each CPU core is and/or …

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## [Linearize sum of piecewise linear constraints](https://discourse.julialang.org/t/linearize-sum-of-piecewise-linear-constraints/11176)

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**Author:** [@jacob-roth](https://discourse.julialang.org/u/jacob-roth)\
**Replies:** 0\
**Last updated:** [May 27, 2018, 2:54am UTC](https://discourse.julialang.org/t/linearize-sum-of-piecewise-linear-constraints/11176 "2018-05-27T02:54:46Z")

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Cross posted here, but asking a variant on this forum. I want to write a sum of piecewise linear constraints as an LP and am hoping to compare my approach with how Convex.jl or JuMP does it. In particular, I believe th…

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## [JuMP, start the optimization with a vector](https://discourse.julialang.org/t/jump-start-the-optimization-with-a-vector/10951)

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**Author:** [@mrapo](https://discourse.julialang.org/u/mrapo)\
**Replies:** 8\
**Last updated:** [May 27, 2018, 4:00am UTC](https://discourse.julialang.org/t/jump-start-the-optimization-with-a-vector/10951 "2018-05-27T04:00:34Z")

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I’m trying to minimize a function with JuMP. The variable of the objective function is a 30 element vector x and the optimization is supposed to start from a given vector x0. How can I give vector x0 as the start? If i …

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## [Introducing the package SatelliteToolbox.jl](https://discourse.julialang.org/t/introducing-the-package-satellitetoolbox-jl/10872)

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**Author:** [@Ronis\_BR](https://discourse.julialang.org/u/Ronis_BR)\
**Replies:** 11\
**Last updated:** [May 27, 2018, 2:13am UTC](https://discourse.julialang.org/t/introducing-the-package-satellitetoolbox-jl/10872 "2018-05-27T02:13:59Z")

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Hi guys! Today, I finally made public the SatelliteToolbox.jl. This is a toolbox constructed at the Brazilian National Institute for Space Research (INPE) that contains a lot of useful algorithms for satellite simulatio…

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## [Tutor/Teacher for help to solve LP problem with column generation (PSAT and condSAT)](https://discourse.julialang.org/t/tutor-teacher-for-help-to-solve-lp-problem-with-column-generation-psat-and-condsat/11156)

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**Author:** [@Isabela\_Valonni](https://discourse.julialang.org/u/Isabela_Valonni)\
**Replies:** 1\
**Last updated:** [May 26, 2018, 3:36pm UTC](https://discourse.julialang.org/t/tutor-teacher-for-help-to-solve-lp-problem-with-column-generation-psat-and-condsat/11156 "2018-05-26T15:36:31Z")

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I am from python, and I am trying to start with Julia. I would like to find someone as a teacher for help me with a specific problem of satisfiability called PSAT and CONSAT and code it in Julia using column generation. …

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## [Recipes distinguishing plot! from plot, for Plots.jl](https://discourse.julialang.org/t/recipes-distinguishing-plot-from-plot-for-plots-jl/11143)

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**Author:** [@improbable22](https://discourse.julialang.org/u/improbable22)\
**Replies:** 1\
**Last updated:** [May 25, 2018, 8:15pm UTC](https://discourse.julialang.org/t/recipes-distinguishing-plot-from-plot-for-plots-jl/11143 "2018-05-25T20:15:07Z")

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As the title says, is there a way for a recipe to distinguish whether it was called from plot!() rather than plot()? For a trivial example, suppose p = plot(x::MyType) works out limits for axes, and normalises somehow, …

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## [Modify equality constraints in JuMP](https://discourse.julialang.org/t/modify-equality-constraints-in-jump/10982)

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**Author:** [@pierre-haessig](https://discourse.julialang.org/u/pierre-haessig)\
**Replies:** 2\
**Last updated:** [May 25, 2018, 4:12pm UTC](https://discourse.julialang.org/t/modify-equality-constraints-in-jump/10982 "2018-05-25T16:12:10Z")

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Hello, In JuMP 0.18 documentation on Problem Modification, I read that JuMP does not currently support changing constraint coefficients. For less-than and greater-than constraints, the right-hand-side can be changed. …

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## [GLVisualize - Render dynamically created and destroyed particles](https://discourse.julialang.org/t/glvisualize-render-dynamically-created-and-destroyed-particles/11125)

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**Author:** [@skleinbo](https://discourse.julialang.org/u/skleinbo)\
**Replies:** 1\
**Last updated:** [May 25, 2018, 2:08pm UTC](https://discourse.julialang.org/t/glvisualize-render-dynamically-created-and-destroyed-particles/11125 "2018-05-25T14:08:01Z")

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Hi everyone, I am looking for a way to realize the following situation with GLVisualize: Given a dynamics under which “particles” are created and destroyed. Output is a vector of positions. I would like to visualize t…

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## [Consistent plotting attributes](https://discourse.julialang.org/t/consistent-plotting-attributes/10822)

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**Author:** [@yakir12](https://discourse.julialang.org/u/yakir12)\
**Replies:** 13\
**Last updated:** [May 25, 2018, 12:47pm UTC](https://discourse.julialang.org/t/consistent-plotting-attributes/10822 "2018-05-25T12:47:52Z")

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I’m plotting the same stuff across multiple different plots. To make things look consistent I want the same things to have the same look, regardless of which plot they are in. What is the best way to accomplish that? He…

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## [\[ANN\] EmpiricalCDFs.jl registered and documented](https://discourse.julialang.org/t/ann-empiricalcdfs-jl-registered-and-documented/11127)

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**Author:** [@jlapeyre](https://discourse.julialang.org/u/jlapeyre)\
**Replies:** 0\
**Last updated:** [May 24, 2018, 12:36pm UTC](https://discourse.julialang.org/t/ann-empiricalcdfs-jl-registered-and-documented/11127 "2018-05-24T12:36:40Z")

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I have just registered EmpiricalCDFs.jl and documented it with Documenter.jl. I gave a brief description of the package a few weeks ago: I have used it in conjunction with the following, as yet unregistered, package …

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## [\[ANN\] InverseLaplace.jl](https://discourse.julialang.org/t/ann-inverselaplace-jl/11126)

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**Author:** [@jlapeyre](https://discourse.julialang.org/u/jlapeyre)\
**Replies:** 0\
**Last updated:** [May 24, 2018, 12:24pm UTC](https://discourse.julialang.org/t/ann-inverselaplace-jl/11126 "2018-05-24T12:24:47Z")

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InverseLaplace.jl provides a three methods for numerical inversion of Laplace transforms. This has been around for a while. But recently, I cleaned up the documentation and registered the package.

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## [Avoiding Plotting to dense plots, saveat not working](https://discourse.julialang.org/t/avoiding-plotting-to-dense-plots-saveat-not-working/9540)

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**Author:** [@Torkel](https://discourse.julialang.org/u/Torkel)\
**Replies:** 8\
**Last updated:** [May 24, 2018, 9:18am UTC](https://discourse.julialang.org/t/avoiding-plotting-to-dense-plots-saveat-not-working/9540 "2018-05-24T09:18:17Z")

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I am running simulations of SDEs and plotting the results. I keep having problem that Jupyter crashes, despite that the simulations shouldn’t be that intense. I think hat I have tracked the problems to the plots being to…

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## [Can we make horizontal bar plots in Plots.jl?](https://discourse.julialang.org/t/can-we-make-horizontal-bar-plots-in-plots-jl/11096)

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**Author:** [@Ali\_Vahdati](https://discourse.julialang.org/u/Ali_Vahdati)\
**Replies:** 2\
**Last updated:** [May 24, 2018, 8:15am UTC](https://discourse.julialang.org/t/can-we-make-horizontal-bar-plots-in-plots-jl/11096 "2018-05-24T08:15:29Z")

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Something similar to barh in Matplotlib. I see there is a barh function in Plots, but for gr/pyplot/plotlyjs backends, it returns the following error: The backend must not support the series type Val{:barh}, and there i…

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## [How to obtain the coefficients of linear constraints in JuMP](https://discourse.julialang.org/t/how-to-obtain-the-coefficients-of-linear-constraints-in-jump/11117)

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**Author:** [@CanLi1](https://discourse.julialang.org/u/CanLi1)\
**Replies:** 1\
**Last updated:** [May 24, 2018, 3:10am UTC](https://discourse.julialang.org/t/how-to-obtain-the-coefficients-of-linear-constraints-in-jump/11117 "2018-05-24T03:10:52Z")

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Hi folks, I constructed a linear model in JuMP by loading an .lp file. lp = Model(solver=CPLEX.CplexSolver()) lp.internalModel = MathProgBase.LinearQuadraticModel(lp.solver) MathProgBase.loadproblem!(lp.internalModel…

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## [How to get the variable value inside a JuMP model to insert it into a function?](https://discourse.julialang.org/t/how-to-get-the-variable-value-inside-a-jump-model-to-insert-it-into-a-function/11108)

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**Author:** [@cfrodriguez](https://discourse.julialang.org/u/cfrodriguez)\
**Replies:** 2\
**Last updated:** [May 24, 2018, 12:03am UTC](https://discourse.julialang.org/t/how-to-get-the-variable-value-inside-a-jump-model-to-insert-it-into-a-function/11108 "2018-05-24T00:03:39Z")

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Hi everyone! I order to avoid unnecessary variables, I need to get a JuMP variable value in each iteration from model to insert it into a function and use it in a @NLexpression. The function is function fy1(x1,x2,x3,x…

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## [Ipopt solver: no method matching setvartype!](https://discourse.julialang.org/t/ipopt-solver-no-method-matching-setvartype/11091)

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**Author:** [@tfk17lstm](https://discourse.julialang.org/u/tfk17lstm)\
**Replies:** 1\
**Last updated:** [May 23, 2018, 11:45pm UTC](https://discourse.julialang.org/t/ipopt-solver-no-method-matching-setvartype/11091 "2018-05-23T23:45:29Z")

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Dear colleagues, I was using juliabox (because for the moment I can no install solvers in my julia) and I am using the same model that I use for my model with linear costs. This is the model: #dispatch with quadratic co…

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## [Renaming columns in DataFramesMeta with spaces](https://discourse.julialang.org/t/renaming-columns-in-dataframesmeta-with-spaces/11101)

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**Author:** [@jacobcvt12](https://discourse.julialang.org/u/jacobcvt12)\
**Replies:** 2\
**Last updated:** [May 23, 2018, 7:14pm UTC](https://discourse.julialang.org/t/renaming-columns-in-dataframesmeta-with-spaces/11101 "2018-05-23T19:14:38Z")

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I’ve created the following dataset: d = DataFrame(x=randn(100)) d\[Symbol("Y 2")\] = randn(100) I can rename the second column via rename!(d, Symbol("Y 2") =\> :Y) But I would like to rename it via a DataFramesMeta chai…

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## [Higher order derivatives in Flux](https://discourse.julialang.org/t/higher-order-derivatives-in-flux/11051)

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**Author:** [@baggepinnen](https://discourse.julialang.org/u/baggepinnen)\
**Replies:** 3\
**Last updated:** [May 22, 2018, 3:08pm UTC](https://discourse.julialang.org/t/higher-order-derivatives-in-flux/11051 "2018-05-22T15:08:56Z")

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As I understand it, Flux.jl does not support the calculation of higher-order derivatives as of yet (please correct me if I’m wrong). Are there any plans to support this in the future? I opened an issue a while back Flux.…

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## [PyPlot Continuing?](https://discourse.julialang.org/t/pyplot-continuing/10557)

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**Author:** [@iwelch](https://discourse.julialang.org/u/iwelch)\
**Replies:** 21\
**Last updated:** [May 22, 2018, 2:13pm UTC](https://discourse.julialang.org/t/pyplot-continuing/10557 "2018-05-22T14:13:36Z")

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I just tried PyPlot again. macos. I wanted to recreate the contour plots in https://github.com/gizmaa/Julia\_Examples/blob/master/pyplot\_surfaceplot.jl 0.6 both the registered and master fail in 0.6.2. in the example …

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## [Piecewise Linearlization of Quadratic functions](https://discourse.julialang.org/t/piecewise-linearlization-of-quadratic-functions/10988)

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**Author:** [@tfk17lstm](https://discourse.julialang.org/u/tfk17lstm)\
**Replies:** 5\
**Last updated:** [May 22, 2018, 7:06am UTC](https://discourse.julialang.org/t/piecewise-linearlization-of-quadratic-functions/10988 "2018-05-22T07:06:29Z")

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Dear colleagues, I have managed to implement the unit commitment problem with JuMP adding the time varying constrains that I mentioned in my last post. I was using the Cbc solver and I would like to know if JuMP has a f…

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## [Constraint optimization without gradient](https://discourse.julialang.org/t/constraint-optimization-without-gradient/11040)

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**Author:** [@sarnatas](https://discourse.julialang.org/u/sarnatas)\
**Replies:** 3\
**Last updated:** [May 21, 2018, 12:23pm UTC](https://discourse.julialang.org/t/constraint-optimization-without-gradient/11040 "2018-05-21T12:23:23Z")

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Hello, I am very new in Julia, so sorry in advance for my questions. I have some issues about the optimize function from Optim.jl package. First of all, I was not able to find a complete list with description of every…

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## [Cannot solve A\\b = x with sparse matrix A - Julia V 0.6.2](https://discourse.julialang.org/t/cannot-solve-a-b-x-with-sparse-matrix-a-julia-v-0-6-2/10994)

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**Author:** [@jeertmans](https://discourse.julialang.org/u/jeertmans)\
**Replies:** 11\
**Last updated:** [May 20, 2018, 5:50am UTC](https://discourse.julialang.org/t/cannot-solve-a-b-x-with-sparse-matrix-a-julia-v-0-6-2/10994 "2018-05-20T05:50:56Z")

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Hello, I’ve been searching for a while now and I cannot find any information on an efficient way to solve sparse linear systems using Julia. It seems like no lufact method is implemented for sparse matrices as the Meth…

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## [Matrix-free linear solvers for DifferentialEquations.jl](https://discourse.julialang.org/t/matrix-free-linear-solvers-for-differentialequations-jl/10968)

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**Author:** [@tobydriscoll](https://discourse.julialang.org/u/tobydriscoll)\
**Replies:** 4\
**Last updated:** [May 18, 2018, 6:31pm UTC](https://discourse.julialang.org/t/matrix-free-linear-solvers-for-differentialequations-jl/10968 "2018-05-18T18:31:58Z")

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I’m trying to solve a DAE (mass matrix form) for a 2D spectral discretization. The number of DOF is going to be large, and the Jacobian, which I compute explicitly, is not especially sparse. I’d like to use a preconditi…

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## [LLVM LoadError: Permission Denied (EACCES)](https://discourse.julialang.org/t/llvm-loaderror-permission-denied-eacces/10941)

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**Author:** [@cuchxq](https://discourse.julialang.org/u/cuchxq)\
**Replies:** 4\
**Last updated:** [May 18, 2018, 3:04pm UTC](https://discourse.julialang.org/t/llvm-loaderror-permission-denied-eacces/10941 "2018-05-18T15:04:48Z")

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Hi, everyone, I am using Julia on a cluster. But I am having error from LLVM. Here is the steps I took: $./julia \_ \_ \_(\_)\_ | A fresh approach to technical computing (\_) | (\_) (\_) | Documentation…

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## [Juno slow to execute JumP models](https://discourse.julialang.org/t/juno-slow-to-execute-jump-models/10981)

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**Author:** [@jayce\_ram](https://discourse.julialang.org/u/jayce_ram)\
**Replies:** 4\
**Last updated:** [May 18, 2018, 11:47am UTC](https://discourse.julialang.org/t/juno-slow-to-execute-jump-models/10981 "2018-05-18T11:47:18Z")

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I have been using Atom to execute the file that contains my LP problem. However, it has been becoming too slow and usually I have to force close of Atom because it bugs. My specifications are: Windows 7 and Juno for Ju…

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## [Pushing into a dictionary by accumulating the values of JumpVariables](https://discourse.julialang.org/t/pushing-into-a-dictionary-by-accumulating-the-values-of-jumpvariables/10952)

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**Author:** [@jayce\_ram](https://discourse.julialang.org/u/jayce_ram)\
**Replies:** 3\
**Last updated:** [May 18, 2018, 9:03am UTC](https://discourse.julialang.org/t/pushing-into-a-dictionary-by-accumulating-the-values-of-jumpvariables/10952 "2018-05-18T09:03:29Z")

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I have been using Jump to model a LP. The variable in my problem can be represented as follow: x\_prod\[year, hour, site, product\] In my obj function I need something like that, for all the sites existing sum(annual\_p…

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## [Time varying constrained optimization](https://discourse.julialang.org/t/time-varying-constrained-optimization/10926)

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**Author:** [@tfk17lstm](https://discourse.julialang.org/u/tfk17lstm)\
**Replies:** 8\
**Last updated:** [May 17, 2018, 9:00am UTC](https://discourse.julialang.org/t/time-varying-constrained-optimization/10926 "2018-05-17T09:00:51Z")

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Dear Julia community, This is Edgar a completely newbie in Julia that has been looking for an alternative to R and Matlab for solving optimization problems. After reading some examples available at JuliaOpt I think that…

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## [Save DataFrame containing arrays](https://discourse.julialang.org/t/save-dataframe-containing-arrays/10927)

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**Author:** [@LaurentPlagne](https://discourse.julialang.org/u/LaurentPlagne)\
**Replies:** 4\
**Last updated:** [May 16, 2018, 12:52pm UTC](https://discourse.julialang.org/t/save-dataframe-containing-arrays/10927 "2018-05-16T12:52:51Z")

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I want to manipulate performance experiments data, store/load these data from a file. I try to use DataFrames.jl which looks OK. When I want to store my data in a csv file, it fails if my data contains arrays of floats. …

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## [LP Barrier solve times scaling badly with number of threads](https://discourse.julialang.org/t/lp-barrier-solve-times-scaling-badly-with-number-of-threads/10907)

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**Author:** [@NiclasMattsson](https://discourse.julialang.org/u/NiclasMattsson)\
**Replies:** 1\
**Last updated:** [May 16, 2018, 1:43am UTC](https://discourse.julialang.org/t/lp-barrier-solve-times-scaling-badly-with-number-of-threads/10907 "2018-05-16T01:43:23Z")

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This is probably not Julia related but could conceivably be due to an issue with CPLEX.jl, so I hope it’s OK that I ask my question here in the optimization subforum. I have a linear programming model written in JuMP tha…

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## [Pmap with in place functions](https://discourse.julialang.org/t/pmap-with-in-place-functions/10523)

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**Author:** [@gideonsimpson](https://discourse.julialang.org/u/gideonsimpson)\
**Replies:** 10\
**Last updated:** [May 15, 2018, 9:58pm UTC](https://discourse.julialang.org/t/pmap-with-in-place-functions/10523 "2018-05-15T21:58:54Z")

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I was hoping to use pmap with an in place function, but I’m finding the behavior is not as expected. This example illustrates the issue: addprocs(2); @everywhere function f!(x) @. x+= randn(); x end X = \[zeros…

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