# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=535

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**Page:** 536

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## [Expression vs Constraint](https://discourse.julialang.org/t/expression-vs-constraint/11481)

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**Author:** [@rawls238](https://discourse.julialang.org/u/rawls238)\
**Replies:** 3\
**Last updated:** [June 6, 2018, 6:56pm UTC](https://discourse.julialang.org/t/expression-vs-constraint/11481 "2018-06-06T18:56:54Z")

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Hi, I’m new to using JuMP and still trying to figure out some of the quirks of JuMP. This may also arise from my ignorance of the underlying methods used by the solvers. I’m using the Ipopt solver and solving a non-line…

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## [Why JuliaDB.Table?](https://discourse.julialang.org/t/why-juliadb-table/11473)

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**Author:** [@jamii](https://discourse.julialang.org/u/jamii)\
**Replies:** 1\
**Last updated:** [June 6, 2018, 6:46pm UTC](https://discourse.julialang.org/t/why-juliadb-table/11473 "2018-06-06T18:46:38Z")

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IIRC the original JuliaDB release only had one datastructure, which was similar to the current JuliaDB.NDSparse. I’m curious why Table was added. Is this a UX thing, or so that they can dispatch differently, or some unde…

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## [Model/variable copy error in JuMP 0.18](https://discourse.julialang.org/t/model-variable-copy-error-in-jump-0-18/11449)

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**Author:** [@chkwon](https://discourse.julialang.org/u/chkwon)\
**Replies:** 3\
**Last updated:** [June 6, 2018, 1:55pm UTC](https://discourse.julialang.org/t/model-variable-copy-error-in-jump-0-18/11449 "2018-06-06T13:55:24Z")

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I created a simple model and tried to copy and modify. using JuMP, Clp m = Model(solver=ClpSolver()) set\_A = \[(1,2), (2,3)\] @variable(m, x\[(i,j) in set\_A\]\>=0) @objective(m, Max, sum(x\[(i,j)\] for (i,j) in set\_A) ) @cons…

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## [How to add user-defined nonlinear functions as constraints with JuMP?](https://discourse.julialang.org/t/how-to-add-user-defined-nonlinear-functions-as-constraints-with-jump/11436)

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**Author:** [@mrapo](https://discourse.julialang.org/u/mrapo)\
**Replies:** 3\
**Last updated:** [June 5, 2018, 8:24pm UTC](https://discourse.julialang.org/t/how-to-add-user-defined-nonlinear-functions-as-constraints-with-jump/11436 "2018-06-05T20:24:37Z")

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Is it possible to add user-defined nonlinear functions as constraints in JuMP? I couldn’t find any documentation about a case like this nor any examples where someone would have done this. I mean something like this: J…

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## [Does \`overwrite\_figure=true\` have any effect in notebook using Plots/GR?](https://discourse.julialang.org/t/does-overwrite-figure-true-have-any-effect-in-notebook-using-plots-gr/11458)

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**Author:** [@ronubi](https://discourse.julialang.org/u/ronubi)\
**Replies:** 0\
**Last updated:** [June 6, 2018, 12:49am UTC](https://discourse.julialang.org/t/does-overwrite-figure-true-have-any-effect-in-notebook-using-plots-gr/11458 "2018-06-06T00:49:01Z")

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I read somewhere that if I set the Plots attribute overwrite\_figure=true, the previous plot would not visibly erase (and the Jupyter notebook cell output would remain in position) so that I could get an animation-like ef…

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## [Plots: title -- what if I have subplots?](https://discourse.julialang.org/t/plots-title-what-if-i-have-subplots/10838)

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**Author:** [@BLI](https://discourse.julialang.org/u/BLI)\
**Replies:** 3\
**Last updated:** [June 5, 2018, 2:05pm UTC](https://discourse.julialang.org/t/plots-title-what-if-i-have-subplots/10838 "2018-06-05T14:05:49Z")

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Using Plots: if I have subplots, a title is applied to the subplot. Is there a “supertitle” that is applied for the entire plot, and not for the various subplots?

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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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