# Specific Domains

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

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**Page:** 537

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## [Testing if data is Gamma Distributed](https://discourse.julialang.org/t/testing-if-data-is-gamma-distributed/11198)

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**Author:** [@Torkel](https://discourse.julialang.org/u/Torkel)\
**Replies:** 7\
**Last updated:** [June 5, 2018, 10:55am UTC](https://discourse.julialang.org/t/testing-if-data-is-gamma-distributed/11198 "2018-06-05T10:55:57Z")

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I have a (large) array of data points. When plotting the histogram it looks somewhat gamma distributed. Exactly what would be the procedure for testing whenever this is the case, using Julia? I think I could fit the dat…

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## [Julia now has a native SGP4/SDP4 implementation](https://discourse.julialang.org/t/julia-now-has-a-native-sgp4-sdp4-implementation/11376)

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**Author:** [@Ronis\_BR](https://discourse.julialang.org/u/Ronis_BR)\
**Replies:** 21\
**Last updated:** [June 4, 2018, 10:47pm UTC](https://discourse.julialang.org/t/julia-now-has-a-native-sgp4-sdp4-implementation/11376 "2018-06-04T22:47:33Z")

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Hi guys! I am happy to announce that I finished the first version of the SGP4/SDP4 implementation 100% written in Julia. The source code is part of SatelliteToolbox.jl. Notice that I did not tag yet, so you need to use m…

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## [Multiple plots -- only legends on some](https://discourse.julialang.org/t/multiple-plots-only-legends-on-some/11410)

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**Author:** [@BLI](https://discourse.julialang.org/u/BLI)\
**Replies:** 5\
**Last updated:** [June 4, 2018, 8:59pm UTC](https://discourse.julialang.org/t/multiple-plots-only-legends-on-some/11410 "2018-06-04T20:59:06Z")

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I plot multiple time series in the same plot, one with nominal parameter value and the others a result of Monte Carlo runs. I only want label on the one with nominal value… I tried to do: plot(…, label="\_nolabel\_") fo…

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## [MultiJuMP AND CPLEX](https://discourse.julialang.org/t/multijump-and-cplex/11409)

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**Author:** [@UserMorocco](https://discourse.julialang.org/u/UserMorocco)\
**Replies:** 3\
**Last updated:** [June 4, 2018, 1:35pm UTC](https://discourse.julialang.org/t/multijump-and-cplex/11409 "2018-06-04T13:35:59Z")

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Hello, I have a problem with discrete and continous variable, I want to use CPLEX with MultiJuMP, but I get this error : ERROR: MethodError: no method matching NonlinearModel(::CPLEX.CplexSolver) Closest candidates ar…

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## [Best way to call an OpenCL kernel with arguments of type CLArray](https://discourse.julialang.org/t/best-way-to-call-an-opencl-kernel-with-arguments-of-type-clarray/11368)

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**Author:** [@ranocha](https://discourse.julialang.org/u/ranocha)\
**Replies:** 6\
**Last updated:** [June 4, 2018, 9:59am UTC](https://discourse.julialang.org/t/best-way-to-call-an-opencl-kernel-with-arguments-of-type-clarray/11368 "2018-06-04T09:59:45Z")

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I would like to perform some computations on GPUs using CLArrays, since these support standard array syntax. However, I would like to call some existing OpenCL kernels on these CLArrays. Some possibilities that might see…

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## [Adding cuts to a MILP prior to the solving](https://discourse.julialang.org/t/adding-cuts-to-a-milp-prior-to-the-solving/11395)

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**Author:** [@jdeboeck](https://discourse.julialang.org/u/jdeboeck)\
**Replies:** 3\
**Last updated:** [June 4, 2018, 1:25am UTC](https://discourse.julialang.org/t/adding-cuts-to-a-milp-prior-to-the-solving/11395 "2018-06-04T01:25:09Z")

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I am solving a MILP with JuMP and have a set of valid cuts for the linear relaxation. I would like to add all these inequalities as a pool of possible cuts before launching the solving and the branching procedure. The ai…

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## [Optimize() error: "Initial value and slope must be finite"](https://discourse.julialang.org/t/optimize-error-initial-value-and-slope-must-be-finite/11320)

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**Author:** [@stst](https://discourse.julialang.org/u/stst)\
**Replies:** 5\
**Last updated:** [June 2, 2018, 10:25am UTC](https://discourse.julialang.org/t/optimize-error-initial-value-and-slope-must-be-finite/11320 "2018-06-02T10:25:37Z")

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The MWE below (run with Julia 0.6.2 and Optim.jl 0.14.1) errors at an non-reproducible k with the error ERROR: Initial value and slope must be finite. Am I doing something wrong? using Optim srand(83092) n = 200 AtA = r…

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## [Converting MultivariatePolynomials output as a function to be used in JuMP](https://discourse.julialang.org/t/converting-multivariatepolynomials-output-as-a-function-to-be-used-in-jump/11262)

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**Author:** [@Ludo](https://discourse.julialang.org/u/Ludo)\
**Replies:** 7\
**Last updated:** [June 2, 2018, 9:09am UTC](https://discourse.julialang.org/t/converting-multivariatepolynomials-output-as-a-function-to-be-used-in-jump/11262 "2018-06-02T09:09:08Z")

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The objective is to solve a large system of NL equations. Equations should be obtained via polynomial operations and passed on to JuMP as user-defined function. Below is the minuaturised code for eveluating polynomials’ …

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## [Mixed integer non-linear problem + three objectives](https://discourse.julialang.org/t/mixed-integer-non-linear-problem-three-objectives/11140)

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**Author:** [@UserMorocco](https://discourse.julialang.org/u/UserMorocco)\
**Replies:** 1\
**Last updated:** [May 26, 2018, 5:08pm UTC](https://discourse.julialang.org/t/mixed-integer-non-linear-problem-three-objectives/11140 "2018-05-26T17:08:55Z")

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Hello everybody, I’m looking for a julia package to solve : mixed integer nonlinear problem with three objectives. thank you.

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## [JuMP: vector variable to user defined NLobjective](https://discourse.julialang.org/t/jump-vector-variable-to-user-defined-nlobjective/11330)

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**Author:** [@mrapo](https://discourse.julialang.org/u/mrapo)\
**Replies:** 1\
**Last updated:** [June 1, 2018, 10:53am UTC](https://discourse.julialang.org/t/jump-vector-variable-to-user-defined-nlobjective/11330 "2018-06-01T10:53:47Z")

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I I’m trying to optimize an user defined function with JuMP. The variable is a vector of length 30. I’ve tried the following two ways to define the objective, but both of them throw an error. The first way I tried with…

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## [f(t+1) in JuMP](https://discourse.julialang.org/t/f-t-1-in-jump/11241)

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**Author:** [@Guito](https://discourse.julialang.org/u/Guito)\
**Replies:** 4\
**Last updated:** [June 1, 2018, 10:03am UTC](https://discourse.julialang.org/t/f-t-1-in-jump/11241 "2018-06-01T10:03:25Z")

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Hi everyone! I am just starting with JuMP and I’m trying to solve a little battery optimization problem that I used to solve easy in GAMS. Though, I am really stuck in the SoC code because I don’t know how to write f(t+…

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## [JuMP nonlinear optimization error: unrecogniced function](https://discourse.julialang.org/t/jump-nonlinear-optimization-error-unrecogniced-function/11328)

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**Author:** [@mrapo](https://discourse.julialang.org/u/mrapo)\
**Replies:** 1\
**Last updated:** [June 1, 2018, 9:28am UTC](https://discourse.julialang.org/t/jump-nonlinear-optimization-error-unrecogniced-function/11328 "2018-06-01T09:28:42Z")

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What does the following error mean when trying to optimize a nonlinear objective function f: ERROR: LoadError: Unrecognized function "f" used in nonlinear expression. This is how I tried to use the nonlinear features o…

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## [Vcat does not append DataFrame rows as it did in 0.10](https://discourse.julialang.org/t/vcat-does-not-append-dataframe-rows-as-it-did-in-0-10/9823)

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**Author:** [@pasha](https://discourse.julialang.org/u/pasha)\
**Replies:** 77\
**Last updated:** [May 31, 2018, 11:48pm UTC](https://discourse.julialang.org/t/vcat-does-not-append-dataframe-rows-as-it-did-in-0-10/9823 "2018-05-31T23:48:23Z")

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In DataFrames 0.10, we could use vcat() as a way to append differently-shaped DataFrames, much like R’s dplyr::bind\_rows(). You could send two DataFrames with differing columns or column order and it would append the ro…

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## [Ignore comments with CSV.read(...)](https://discourse.julialang.org/t/ignore-comments-with-csv-read/11302)

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**Author:** [@e3c6](https://discourse.julialang.org/u/e3c6)\
**Replies:** 1\
**Last updated:** [May 31, 2018, 7:31pm UTC](https://discourse.julialang.org/t/ignore-comments-with-csv-read/11302 "2018-05-31T19:31:30Z")

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When reading a csv file with CSV.read(…), is it possible to ignore lines that start with a character (for example #)? In other words, I want to read a file that contains comments.

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## [JuMP.jl user-defined function has to return a scalar?](https://discourse.julialang.org/t/jump-jl-user-defined-function-has-to-return-a-scalar/11202)

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**Author:** [@floswald](https://discourse.julialang.org/u/floswald)\
**Replies:** 2\
**Last updated:** [May 31, 2018, 3:48pm UTC](https://discourse.julialang.org/t/jump-jl-user-defined-function-has-to-return-a-scalar/11202 "2018-05-31T15:48:15Z")

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I have a question related to what was asked here some time ago. I want to use JuMP and need to differentiate through a function from the BasisMatrices.jl package and I am having trouble making that work. I don’t understa…

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## [JuMP Dot Product/Norm/NLobjective](https://discourse.julialang.org/t/jump-dot-product-norm-nlobjective/11273)

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**Author:** [@Paul\_McVay](https://discourse.julialang.org/u/Paul_McVay)\
**Replies:** 4\
**Last updated:** [May 31, 2018, 3:28pm UTC](https://discourse.julialang.org/t/jump-dot-product-norm-nlobjective/11273 "2018-05-31T15:28:10Z")

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I’ve run into a number of issues with quadratic objectives in JuMP. A simple example is: m = Model(solver = CplexSolver()) @variable(m, w\[1:10\]) @expression(m, dotproduct, sum(w\[i\]\*w\[i\] for i = 1:10)) If I try to make …

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## [Automatic Differentiation Slow (Slower than Finite-Differences)](https://discourse.julialang.org/t/automatic-differentiation-slow-slower-than-finite-differences/11209)

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**Author:** [@Juser](https://discourse.julialang.org/u/Juser)\
**Replies:** 18\
**Last updated:** [May 31, 2018, 12:57pm UTC](https://discourse.julialang.org/t/automatic-differentiation-slow-slower-than-finite-differences/11209 "2018-05-31T12:57:12Z")

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I am trying to implement a statistical estimator and am having issues with both ForwardDiff and ReverseDiff taking longer to compute gradients than would simple one-sided finite differencing. Below is a minimal example …

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## [\[ANN\] Tasmanian.jl Adaptive Sparse Grid Function Approximation](https://discourse.julialang.org/t/ann-tasmanian-jl-adaptive-sparse-grid-function-approximation/11239)

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**Author:** [@floswald](https://discourse.julialang.org/u/floswald)\
**Replies:** 4\
**Last updated:** [May 29, 2018, 9:56pm UTC](https://discourse.julialang.org/t/ann-tasmanian-jl-adaptive-sparse-grid-function-approximation/11239 "2018-05-29T21:56:30Z")

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Hi, I wrapped the TASMANIAN library for julia in https://github.com/floswald/Tasmanian.jl This provides adaptive sparse grid approximations, useful for people who need to approximate high dimensional functions. The pa…

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## [Solving a simple equation in SymPy.jl fails](https://discourse.julialang.org/t/solving-a-simple-equation-in-sympy-jl-fails/11146)

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**Author:** [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Replies:** 4\
**Last updated:** [May 29, 2018, 9:02pm UTC](https://discourse.julialang.org/t/solving-a-simple-equation-in-sympy-jl-fails/11146 "2018-05-29T21:02:54Z")

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Hello, I tried to use SymPy.jl to solve a simple equation, but it fails. It eats more and more memory until the computer stalls. Two questions: a) where can I file a bug report? b) how can I solve this equation in Ju…

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## [simple example using Plots following with warnings and an error](https://discourse.julialang.org/t/simple-example-using-plots-following-with-warnings-and-an-error/11244)

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**Author:** [@Carsten](https://discourse.julialang.org/u/Carsten)\
**Replies:** 8\
**Last updated:** [May 29, 2018, 7:04pm UTC](https://discourse.julialang.org/t/simple-example-using-plots-following-with-warnings-and-an-error/11244 "2018-05-29T19:04:12Z")

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I am using Julia 0.6.2 (Windows) and the Atom editor After launching Julia and using Plots I’ve got the following warnings: WARNING: using Plots.savefig in module Main conflicts with an existing identifier. WARNING:…

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## [Frame-Heavy Gifs](https://discourse.julialang.org/t/frame-heavy-gifs/11243)

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**Author:** [@Oz\_Wilson](https://discourse.julialang.org/u/Oz_Wilson)\
**Replies:** 0\
**Last updated:** [May 29, 2018, 5:25pm UTC](https://discourse.julialang.org/t/frame-heavy-gifs/11243 "2018-05-29T17:25:32Z")

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I am trying to create a gif with 100 frames, which I assume shouldn’t be a problem if I code it correctly. However, the following code slows to a crawl, and seems to cause a memory leak. using Plots using ProgressMeter …

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## [ECONNRESET error with HTTP.jl](https://discourse.julialang.org/t/econnreset-error-with-http-jl/11228)

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**Author:** [@cstjean](https://discourse.julialang.org/u/cstjean)\
**Replies:** 1\
**Last updated:** [May 29, 2018, 1:10pm UTC](https://discourse.julialang.org/t/econnreset-error-with-http-jl/11228 "2018-05-29T13:10:12Z")

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I’m using HTTP.jl to POST data to a REST service, and every thirty minutes (it’s very regular), I’m hitting ERROR: LoadError: IOError(read: connection reset by peer (ECONNRESET) during request. Does that ring a bell to …

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## [Converting GAMS script to JuMP: Marginal values](https://discourse.julialang.org/t/converting-gams-script-to-jump-marginal-values/11199)

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**Author:** [@Libbum](https://discourse.julialang.org/u/Libbum)\
**Replies:** 2\
**Last updated:** [May 29, 2018, 12:03pm UTC](https://discourse.julialang.org/t/converting-gams-script-to-jump-marginal-values/11199 "2018-05-29T12:03:07Z")

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Hi all, Hopefully just a quick question here: I’m new to optimisation solvers in general so this may something I’ve missed. I’m converting a GAMS script into a JuMP solution (using Ipopt). After the optimisation step, …

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## [Annoucement: Algencan.jl initial release](https://discourse.julialang.org/t/annoucement-algencan-jl-initial-release/11183)

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**Author:** [@pjssilva](https://discourse.julialang.org/u/pjssilva)\
**Replies:** 6\
**Last updated:** [May 29, 2018, 12:00am UTC](https://discourse.julialang.org/t/annoucement-algencan-jl-initial-release/11183 "2018-05-29T00:00:15Z")

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After a long period planning I have finished a first rough implementation of a interface between the Algencan solver for nonlinear optimization (general NLP with constraints) for JuMP / MathProgBase that I am naming Alge…

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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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