# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1556

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

**Page:** 1557

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## [Can I use JuMP 0.18 with Gurobi.jl 0.9.3?](https://discourse.julialang.org/t/can-i-use-jump-0-18-with-gurobi-jl-0-9-3/51220)

<div class="topic-metadata">

**Author:** [@Wei\_Wang](https://discourse.julialang.org/u/Wei_Wang)\
**Replies:** 2\
**Last updated:** [December 3, 2020, 8:01pm UTC](https://discourse.julialang.org/t/can-i-use-jump-0-18-with-gurobi-jl-0-9-3/51220 "2020-12-03T20:01:42Z")

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For some reasons, I currently still have to use JuMP 0.18. When I updated Gurobi to the latest version 9.1 and Gurobi.jl to 0.9.3, I got some problems building my model. When I do it with model=Model(solver=GurobiSolv…

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## [Package dependency to an unregistered version of a registered package](https://discourse.julialang.org/t/package-dependency-to-an-unregistered-version-of-a-registered-package/51218)

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**Author:** [@monty](https://discourse.julialang.org/u/monty)\
**Replies:** 2\
**Last updated:** [December 3, 2020, 7:06pm UTC](https://discourse.julialang.org/t/package-dependency-to-an-unregistered-version-of-a-registered-package/51218 "2020-12-03T19:06:52Z")

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I have a module (package) that has as a dependency a forked version of a registered module. How I can specify this dependency and how I can point to the forked version of the registered module on Github in the Project.to…

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## [Help understanding use of macros over functions that return expressions](https://discourse.julialang.org/t/help-understanding-use-of-macros-over-functions-that-return-expressions/51217)

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**Author:** [@mkarikom](https://discourse.julialang.org/u/mkarikom)\
**Replies:** 1\
**Last updated:** [December 3, 2020, 6:51pm UTC](https://discourse.julialang.org/t/help-understanding-use-of-macros-over-functions-that-return-expressions/51217 "2020-12-03T18:51:50Z")

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The docs are clear about how macros execute before the enclosing code is run, but I’m still having trouble imagining where this is necessary, when we already have functions that return expressions. It’s easy to come up…

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## [Lagging while updating pkg, also adding pkg](https://discourse.julialang.org/t/lagging-while-updating-pkg-also-adding-pkg/51183)

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**Author:** [@basernapairs](https://discourse.julialang.org/u/basernapairs)\
**Replies:** 1\
**Last updated:** [December 3, 2020, 6:30pm UTC](https://discourse.julialang.org/t/lagging-while-updating-pkg-also-adding-pkg/51183 "2020-12-03T18:30:27Z")

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lagging while updating pkg, also adding pkg approx. time: hours (even a days) where this come from?

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## [Accumulating strings dynamically](https://discourse.julialang.org/t/accumulating-strings-dynamically/51209)

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**Author:** [@purplishrock](https://discourse.julialang.org/u/purplishrock)\
**Replies:** 5\
**Last updated:** [December 3, 2020, 5:34pm UTC](https://discourse.julialang.org/t/accumulating-strings-dynamically/51209 "2020-12-03T17:34:34Z")

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I have to dynamically accumulate strings and for each string simply accumulate characters in an array push!(word, c) and then using this nifty one-liner to convert to a string foldl(\*, word) I’m just wondering if tha…

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## [What does mean if memory allocations are shown on struct elements?](https://discourse.julialang.org/t/what-does-mean-if-memory-allocations-are-shown-on-struct-elements/51212)

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**Author:** [@JuergenD](https://discourse.julialang.org/u/JuergenD)\
**Replies:** 0\
**Last updated:** [December 3, 2020, 5:20pm UTC](https://discourse.julialang.org/t/what-does-mean-if-memory-allocations-are-shown-on-struct-elements/51212 "2020-12-03T17:20:55Z")

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Hi, using julia --track-allocation=user the following extract was written into a \*.mem file. What does it mean when track-allocation reports memory allocations on a specific element of the struct? Where do I need to loo…

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## [Help implementing \`copyto!\` for broadcasting](https://discourse.julialang.org/t/help-implementing-copyto-for-broadcasting/51204)

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**Author:** [@pdeffebach](https://discourse.julialang.org/u/pdeffebach)\
**Replies:** 4\
**Last updated:** [December 3, 2020, 5:04pm UTC](https://discourse.julialang.org/t/help-implementing-copyto-for-broadcasting/51204 "2020-12-03T17:04:32Z")

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I have a type DataRow. It’s goal is to act like a row of a DataFrame, but standing on its own. It’s one dimensional It’s indexable It iterates through values It stores values in a Vector{Any} internally I’m trying to …

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## [Method for counting characters in string? count("a", "batman") vs. count('a', "batman")](https://discourse.julialang.org/t/method-for-counting-characters-in-string-count-a-batman-vs-count-a-batman/51153)

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**Author:** [@bradeneliason](https://discourse.julialang.org/u/bradeneliason)\
**Replies:** 7\
**Last updated:** [December 3, 2020, 4:57pm UTC](https://discourse.julialang.org/t/method-for-counting-characters-in-string-count-a-batman-vs-count-a-batman/51153 "2020-12-03T16:57:45Z")

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It seems like there should be a valid method for a calling count with a character and a string. count("a", "batman") # returns 2 as expected count('a', "batman") # ERROR: MethodError: objects of type Char are not call…

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## [Extended function not being seen (Is explicity imported)](https://discourse.julialang.org/t/extended-function-not-being-seen-is-explicity-imported/51200)

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**Author:** [@Annie](https://discourse.julialang.org/u/Annie)\
**Replies:** 5\
**Last updated:** [December 3, 2020, 4:30pm UTC](https://discourse.julialang.org/t/extended-function-not-being-seen-is-explicity-imported/51200 "2020-12-03T16:30:22Z")

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I’ve been looking at extending functions to work with a self-defined data type. Most of them I got working no problem but I am struggling to get one of them working. I define a type mutable struct ImagTimeEvolution{N,T…

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## [Any improvements in threaded exception handling in 1.5?](https://discourse.julialang.org/t/any-improvements-in-threaded-exception-handling-in-1-5/51206)

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**Author:** [@tro3](https://discourse.julialang.org/u/tro3)\
**Replies:** 0\
**Last updated:** [December 3, 2020, 4:20pm UTC](https://discourse.julialang.org/t/any-improvements-in-threaded-exception-handling-in-1-5/51206 "2020-12-03T16:20:03Z")

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Turning back towards maintenance on ThreadPools.jl, were there any improvements in the 1.5 release around exception handling during threaded operations? Historically in 1.3, those exceptions have vanished into the ether…

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## [Spaces for "base measures"](https://discourse.julialang.org/t/spaces-for-base-measures/50594)

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**Author:** [@cscherrer](https://discourse.julialang.org/u/cscherrer)\
**Replies:** 11\
**Last updated:** [December 3, 2020, 4:01pm UTC](https://discourse.julialang.org/t/spaces-for-base-measures/50594 "2020-12-03T16:01:41Z")

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For MeasureTheory.jl, we need a nice way to represent some domains, like continuous sets ℝ, ℝ₊, and 𝕀 (unit interval) Infinite discrete sets ℤ, ℤ₊, ℤ₀₊ Also finite sets a:b, but that’s easier Eventually we’ll need to…

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## [Help using the JuMPeR package](https://discourse.julialang.org/t/help-using-the-jumper-package/51184)

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**Author:** [@RaquelSantos](https://discourse.julialang.org/u/RaquelSantos)\
**Replies:** 1\
**Last updated:** [December 3, 2020, 1:11pm UTC](https://discourse.julialang.org/t/help-using-the-jumper-package/51184 "2020-12-03T13:11:35Z")

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Could someone point me to a tutorial on using JuMPeR? Thanks!!

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## [Saving Profile data](https://discourse.julialang.org/t/saving-profile-data/51173)

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**Author:** [@paulmelis](https://discourse.julialang.org/u/paulmelis)\
**Replies:** 13\
**Last updated:** [December 3, 2020, 10:17am UTC](https://discourse.julialang.org/t/saving-profile-data/51173 "2020-12-03T10:17:48Z")

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Is there a way to save the profiling data gathered by the Profile module? I don’t see a user-facing API for it, although some methods come close, like fetch(). I’d like to capture the profiling statistics of a large batc…

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## [Broadcasting over combinations of inputs](https://discourse.julialang.org/t/broadcasting-over-combinations-of-inputs/50785)

<div class="topic-metadata">

**Author:** [@bmit](https://discourse.julialang.org/u/bmit)\
**Replies:** 5\
**Last updated:** [December 3, 2020, 9:06am UTC](https://discourse.julialang.org/t/broadcasting-over-combinations-of-inputs/50785 "2020-12-03T09:06:41Z")

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I’m looking for a design pattern that will let me broadcast a function over two input lists, returning a 2D array of the output of the function for all possible pairs from the two lists. In other words if my input array…

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## [Coordinate Transformation on mass density](https://discourse.julialang.org/t/coordinate-transformation-on-mass-density/51040)

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**Author:** [@jw3126](https://discourse.julialang.org/u/jw3126)\
**Replies:** 6\
**Last updated:** [June 3, 2026, 9:28am UTC](https://discourse.julialang.org/t/coordinate-transformation-on-mass-density/51040 "2026-06-03T09:28:18Z")

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I have a mass density, which comes from measurement and is represented by a cartesian grid and the average density over each grid cell. I need to do some computations with this density. The final computation output of t…

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## [\[ANN\] LibFaceDetection](https://discourse.julialang.org/t/ann-libfacedetection/51150)

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**Author:** [@sdanisch](https://discourse.julialang.org/u/sdanisch)\
**Replies:** 1\
**Last updated:** [December 3, 2020, 8:11am UTC](https://discourse.julialang.org/t/ann-libfacedetection/51150 "2020-12-03T08:11:28Z")

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In my quest to make it easy to extract the maximal amount of information from my photos, I wrapped libfacedetection: It works pretty well, but still needs to down sample photos (it will not recognize faces correctly on…

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## [Julia Micro-Benchmarks graph](https://discourse.julialang.org/t/julia-micro-benchmarks-graph/50005)

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**Author:** [@markcbaumann](https://discourse.julialang.org/u/markcbaumann)\
**Replies:** 10\
**Last updated:** [December 3, 2020, 6:42am UTC](https://discourse.julialang.org/t/julia-micro-benchmarks-graph/50005 "2020-12-03T06:42:57Z")

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I have a question about the graph on Julia Micro-Benchmarks What is the vertical axis of this graph? What are its units?

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## [Problem using modules](https://discourse.julialang.org/t/problem-using-modules/50960)

<div class="topic-metadata">

**Author:** [@Jakub\_Mitura](https://discourse.julialang.org/u/Jakub_Mitura)\
**Replies:** 11\
**Last updated:** [December 3, 2020, 6:07am UTC](https://discourse.julialang.org/t/problem-using-modules/50960 "2020-12-03T06:07:17Z")

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Hello I used PkgTemplates.jl to create package all works I have directory structure as below but when I try to test a package from src (using generated by a template test file) I get LoadError: ArgumentError: Packa…

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## [Flux Zygote Gradient: Understanding Mutating arrays is not supported](https://discourse.julialang.org/t/flux-zygote-gradient-understanding-mutating-arrays-is-not-supported/46324)

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**Author:** [@rakeshvar](https://discourse.julialang.org/u/rakeshvar)\
**Replies:** 21\
**Last updated:** [December 3, 2020, 5:21am UTC](https://discourse.julialang.org/t/flux-zygote-gradient-understanding-mutating-arrays-is-not-supported/46324 "2020-12-03T05:21:49Z")

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Namaste, I am trying to implement CTC loss in Flux/Zygote. And running into Error: Mutating arrays is not supported. So I cooked up the toy example below to gain better understanding. Given an input x, I perform some s…

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## [Odd syntax error with type parameter and array literal](https://discourse.julialang.org/t/odd-syntax-error-with-type-parameter-and-array-literal/51164)

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**Author:** [@hexane](https://discourse.julialang.org/u/hexane)\
**Replies:** 1\
**Last updated:** [December 3, 2020, 3:02am UTC](https://discourse.julialang.org/t/odd-syntax-error-with-type-parameter-and-array-literal/51164 "2020-12-03T03:02:13Z")

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I recently ran into a weird parsing error with Julia when defining the following function: julia\> function to\_array(val::T)::Array{T} where {T} \[val\] end ERROR: syntax: space before "\[" not allowed in "{T} \[" at REPL\[14…

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## [DataFrame in Nested Loop](https://discourse.julialang.org/t/dataframe-in-nested-loop/51046)

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**Author:** [@Rojesh](https://discourse.julialang.org/u/Rojesh)\
**Replies:** 8\
**Last updated:** [December 3, 2020, 2:53am UTC](https://discourse.julialang.org/t/dataframe-in-nested-loop/51046 "2020-12-03T02:53:23Z")

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I’m trying to append data to a dataframe through nested loop something similar to the following example, but the resulting dataframe is empty. How can I fix this ? I’ll be calling another function instead of DataFrame t…

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## [It there a way or package to solve the nonlinear mixed complementarity problem?](https://discourse.julialang.org/t/it-there-a-way-or-package-to-solve-the-nonlinear-mixed-complementarity-problem/51161)

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**Author:** [@jshengdb](https://discourse.julialang.org/u/jshengdb)\
**Replies:** 2\
**Last updated:** [December 3, 2020, 2:38am UTC](https://discourse.julialang.org/t/it-there-a-way-or-package-to-solve-the-nonlinear-mixed-complementarity-problem/51161 "2020-12-03T02:38:35Z")

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Hi Julia user: I was wondering if there was a way or package to model and solver the nonlinear mixed complementarity problem? I know now we can model the linear complementarity problem by using complement constraints in…

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## [How to use \`in\` with @where \[DataFramesMeta\]?](https://discourse.julialang.org/t/how-to-use-in-with-where-dataframesmeta/2176)

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**Author:** [@sylvaticus](https://discourse.julialang.org/u/sylvaticus)\
**Replies:** 6\
**Last updated:** [December 3, 2020, 1:36am UTC](https://discourse.julialang.org/t/how-to-use-in-with-where-dataframesmeta/2176 "2020-12-03T01:36:07Z")

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As from the title, how to use in with @where (DataFramesMeta)? e.g. @where(df, :x in \["cat1", "cat2"\]) I did already try :x .in \["cat1", "cat2"\] or .in(:x, \["cat1", "cat2"\])…

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## [Rand/logpdf semantic consistency](https://discourse.julialang.org/t/rand-logpdf-semantic-consistency/50904)

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**Author:** [@cscherrer](https://discourse.julialang.org/u/cscherrer)\
**Replies:** 12\
**Last updated:** [December 3, 2020, 1:07am UTC](https://discourse.julialang.org/t/rand-logpdf-semantic-consistency/50904 "2020-12-03T01:07:54Z")

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There’s a subtle issue I’ve mentioned before involving rand and logpdf that has gotten in the way of composability. I’m thinking in terms of Soss and MeasureTheory.jl, but I thought I’d post here since it may be helpful …

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## [How does one build Julia using git for multiple stdlibs?](https://discourse.julialang.org/t/how-does-one-build-julia-using-git-for-multiple-stdlibs/49451)

<div class="topic-metadata">

**Author:** [@tim.holy](https://discourse.julialang.org/u/tim.holy)\
**Replies:** 8\
**Last updated:** [December 3, 2020, 12:29am UTC](https://discourse.julialang.org/t/how-does-one-build-julia-using-git-for-multiple-stdlibs/49451 "2020-12-03T00:29:15Z")

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One can build Julia with make DEPS\_GIT=Pkg, which causes the Pkg stdlib to be built from a git repo of Pkg rather than downloading a tarball. But make DEPS\_GIT=(Pkg Tar) doesn’t work. Any hints about how to get two or mo…

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## [ANN: Transducers.jl 0.3. taking "zeros" seriously, type stability improvements, fusible groupby, OnlineStats, "GPU support", and more](https://discourse.julialang.org/t/ann-transducers-jl-0-3-taking-zeros-seriously-type-stability-improvements-fusible-groupby-onlinestats-gpu-support-and-more/26873)

<div class="topic-metadata">

**Author:** [@tkf](https://discourse.julialang.org/u/tkf)\
**Replies:** 29\
**Last updated:** [December 2, 2020, 10:23pm UTC](https://discourse.julialang.org/t/ann-transducers-jl-0-3-taking-zeros-seriously-type-stability-improvements-fusible-groupby-onlinestats-gpu-support-and-more/26873 "2020-12-02T22:23:00Z")

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Hi, I’m happy to announce that Transducers 0.3 is released. Let me share some highlights. If you are new to Transducers checkout the last discussion ANN: Transducers.jl, efficient and composable algorithms for map- and…

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## [Delegating efficiently iteration from one object to another](https://discourse.julialang.org/t/delegating-efficiently-iteration-from-one-object-to-another/51098)

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**Author:** [@Jean\_Michel](https://discourse.julialang.org/u/Jean_Michel)\
**Replies:** 40\
**Last updated:** [December 2, 2020, 10:17pm UTC](https://discourse.julialang.org/t/delegating-efficiently-iteration-from-one-object-to-another/51098 "2020-12-02T22:17:26Z")

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My problem occured while trying to write an efficient iterator for permutations groups: they can be efficient generated by running throught the products of some lists of permutations (some transversals). I …

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## [Constraining binary integer variables with indicator constraints](https://discourse.julialang.org/t/constraining-binary-integer-variables-with-indicator-constraints/51043)

<div class="topic-metadata">

**Author:** [@bvilmann](https://discourse.julialang.org/u/bvilmann)\
**Replies:** 9\
**Last updated:** [December 2, 2020, 10:11pm UTC](https://discourse.julialang.org/t/constraining-binary-integer-variables-with-indicator-constraints/51043 "2020-12-02T22:11:15Z")

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I want to constrain binary integer variables, x, with indicator constraints to express a change in a binary integer variable over a specific iterator, t. I thought this could be nice since the different cases are obviou…

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## [Improving speed of convolutions of same sized arrays](https://discourse.julialang.org/t/improving-speed-of-convolutions-of-same-sized-arrays/51124)

<div class="topic-metadata">

**Author:** [@heltonmc](https://discourse.julialang.org/u/heltonmc)\
**Replies:** 6\
**Last updated:** [December 2, 2020, 9:44pm UTC](https://discourse.julialang.org/t/improving-speed-of-convolutions-of-same-sized-arrays/51124 "2020-12-02T21:44:18Z")

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Hi everyone, I have been trying to improve the performance of a model that I am using to fit experimental data with LsqFit. Unfortunately, after calculating the theoretical solution it must be convolved with a same size…

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## [Dereferencing an Array of Struct Pointer](https://discourse.julialang.org/t/dereferencing-an-array-of-struct-pointer/51145)

<div class="topic-metadata">

**Author:** [@Brad\_Carman](https://discourse.julialang.org/u/Brad_Carman)\
**Replies:** 6\
**Last updated:** [December 2, 2020, 9:24pm UTC](https://discourse.julialang.org/t/dereferencing-an-array-of-struct-pointer/51145 "2020-12-02T21:24:18Z")

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I’m having trouble dereferencing a pointer to an array of structs. See the following code for an example: mutable struct Test x::Float64 end tests = \[Test(1.2), Test(3.4)\] tests\_ptr = Base.unsafe\_convert(Ptr{Test…

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