# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1630

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

**Page:** 1631

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## [Change parameters in a model in specific time with DifferentialEquations](https://discourse.julialang.org/t/change-parameters-in-a-model-in-specific-time-with-differentialequations/36930)

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**Author:** [@askery](https://discourse.julialang.org/u/askery)\
**Replies:** 8\
**Last updated:** [September 16, 2020, 11:50am UTC](https://discourse.julialang.org/t/change-parameters-in-a-model-in-specific-time-with-differentialequations/36930 "2020-09-16T11:50:08Z")

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Guys, I am really new to Julia. I came to solve a system of ODE and want to stay. For sure my question is trivial, but I looked for similar solutions and could not find for 3 days. Suppose I am solving Lorentz equations…

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## [Interpolating into a series of matrices](https://discourse.julialang.org/t/interpolating-into-a-series-of-matrices/46635)

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**Author:** [@Raf](https://discourse.julialang.org/u/Raf)\
**Replies:** 9\
**Last updated:** [September 16, 2020, 11:06am UTC](https://discourse.julialang.org/t/interpolating-into-a-series-of-matrices/46635 "2020-09-16T11:06:09Z")

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I’m writing a package that needs to generically interpolate a matrix from a time-series of matrices. For example, maybe it’s a series of spatial matrices of monthly mean values, that I would like to interpolate to a sin…

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## [Julia 1.5, error with JuliaInterpreter but it is not installed](https://discourse.julialang.org/t/julia-1-5-error-with-juliainterpreter-but-it-is-not-installed/46644)

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**Author:** [@Olivier\_Merchiers](https://discourse.julialang.org/u/Olivier_Merchiers)\
**Replies:** 5\
**Last updated:** [September 16, 2020, 9:42am UTC](https://discourse.julialang.org/t/julia-1-5-error-with-juliainterpreter-but-it-is-not-installed/46644 "2020-09-16T09:42:50Z")

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Hello everyone, I have this weird error when loading one of my packages in Julia 1.5. In 1.4, there is no issue at all: Error: evaluation error starting at /home/omerchiers/Documents/Travail/02-Recherche/Informatique/D…

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## [Not defined error](https://discourse.julialang.org/t/not-defined-error/46685)

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**Author:** [@iHany](https://discourse.julialang.org/u/iHany)\
**Replies:** 4\
**Last updated:** [September 16, 2020, 8:58am UTC](https://discourse.julialang.org/t/not-defined-error/46685 "2020-09-16T08:58:57Z")

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Sooooo confusing using Julia :frowning: I don’t understand why the following simple codes doesn’t work at all with error message AbstractGlidingVehicle not defined. Even my other custom package is similarly written, bu…

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## [Reuse gurobi license](https://discourse.julialang.org/t/reuse-gurobi-license/46680)

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**Author:** [@Ken\_Lin](https://discourse.julialang.org/u/Ken_Lin)\
**Replies:** 1\
**Last updated:** [September 16, 2020, 3:30am UTC](https://discourse.julialang.org/t/reuse-gurobi-license/46680 "2020-09-16T03:30:38Z")

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I would like my code to reuse a single gurobi license instead of one per model. The following works for me: const GRB\_ENV = Gurobi.Env() m1 = Model(solver=GurobiSolver(GRB\_ENV)) m2 = Model(solver=GurobiSolver(GRB\_ENV))…

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## [Trouble Pre-allocating Outputs](https://discourse.julialang.org/t/trouble-pre-allocating-outputs/39610)

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**Author:** [@loki](https://discourse.julialang.org/u/loki)\
**Replies:** 9\
**Last updated:** [September 16, 2020, 3:30am UTC](https://discourse.julialang.org/t/trouble-pre-allocating-outputs/39610 "2020-09-16T03:30:26Z")

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Hello, I was hoping to get some advice regarding how to properly go about Pre-allocating outputs for a more complicated example and speeding a function. I’ve read through others’ posts and the performance guide but was s…

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## [Trying to bench two code samples and I'm getting different results @time vs @btime](https://discourse.julialang.org/t/trying-to-bench-two-code-samples-and-im-getting-different-results-time-vs-btime/46576)

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**Author:** [@conditionality](https://discourse.julialang.org/u/conditionality)\
**Replies:** 3\
**Last updated:** [September 16, 2020, 3:18am UTC](https://discourse.julialang.org/t/trying-to-bench-two-code-samples-and-im-getting-different-results-time-vs-btime/46576 "2020-09-16T03:18:50Z")

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I have a DataFrame “results” that is sorted by \_.date. I’m experimenting to see the difference between using a filter (A): results |\> @filter(\_.date \>= Dates.Date(2018,1,1) && \_.date \<= Dates.Date(2019,1,1)) vs direct …

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## [Getting started with Julia and Robotics Projects](https://discourse.julialang.org/t/getting-started-with-julia-and-robotics-projects/46670)

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**Author:** [@josiahe](https://discourse.julialang.org/u/josiahe)\
**Replies:** 3\
**Last updated:** [September 16, 2020, 3:17am UTC](https://discourse.julialang.org/t/getting-started-with-julia-and-robotics-projects/46670 "2020-09-16T03:17:32Z")

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Hello, I am a recent mechanical engineering graduate and discovered Julia online. I am interested in simulating and optimizing some custom robotics designs and wanted some input from people who are more experienced with…

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## [Converting Day to Int](https://discourse.julialang.org/t/converting-day-to-int/37582)

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**Author:** [@ultradian](https://discourse.julialang.org/u/ultradian)\
**Replies:** 5\
**Last updated:** [September 16, 2020, 2:22am UTC](https://discourse.julialang.org/t/converting-day-to-int/37582 "2020-09-16T02:22:14Z")

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I read through the docs on the Dates Module, but I can’t figure out how to convert a Day to an Int. I have an array of {Day,1}, and want to perform mean and std and so on. Also, for Plotting they seem to be treated more…

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## [Status for stacked environments](https://discourse.julialang.org/t/status-for-stacked-environments/18558)

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**Author:** [@krcools](https://discourse.julialang.org/u/krcools)\
**Replies:** 3\
**Last updated:** [September 16, 2020, 2:17am UTC](https://discourse.julialang.org/t/status-for-stacked-environments/18558 "2020-09-16T02:17:46Z")

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Is there a way to make pkg\>status show all packages available in the LOAD\_PATH stack as opposed to only those added to the topmost environment?

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## [Senior Software Engineer - SF Bay Area - Remote](https://discourse.julialang.org/t/senior-software-engineer-sf-bay-area-remote/45720)

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**Author:** [@mofi](https://discourse.julialang.org/u/mofi)\
**Replies:** 5\
**Last updated:** [September 16, 2020, 12:45am UTC](https://discourse.julialang.org/t/senior-software-engineer-sf-bay-area-remote/45720 "2020-09-16T00:45:57Z")

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Orchard Ultrasound Innovation is a well-funded startup in stealth-mode consisting of entrepreneurs, inventors, scientists, and engineers inventing new ultrasound technology to solve some of humanity’s big challenges. We …

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## [Vector of Vectors: Type Issue and Tuple Question](https://discourse.julialang.org/t/vector-of-vectors-type-issue-and-tuple-question/46640)

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**Author:** [@Nathan\_Boyer](https://discourse.julialang.org/u/Nathan_Boyer)\
**Replies:** 14\
**Last updated:** [September 15, 2020, 8:56pm UTC](https://discourse.julialang.org/t/vector-of-vectors-type-issue-and-tuple-question/46640 "2020-09-15T20:56:33Z")

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I am trying to understand the difference between the two ways I found to create a vector of vectors below. I found Option 1 in this post, which works nicely but isn’t very customizable. Option 2 also works, but it can’t …

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## [Derivative with terminate callback](https://discourse.julialang.org/t/derivative-with-terminate-callback/46409)

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**Author:** [@colinclout12](https://discourse.julialang.org/u/colinclout12)\
**Replies:** 6\
**Last updated:** [September 15, 2020, 8:47pm UTC](https://discourse.julialang.org/t/derivative-with-terminate-callback/46409 "2020-09-15T20:47:16Z")

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I’d like to program a differential equation that runs till it reaches a particular state (e.g. one of the space variables is zero), and then train the some parameters that define the equation so the system reaches the te…

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## [Upwind advection scheme with periodic boundary conditions](https://discourse.julialang.org/t/upwind-advection-scheme-with-periodic-boundary-conditions/46658)

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**Author:** [@ElOceanografo](https://discourse.julialang.org/u/ElOceanografo)\
**Replies:** 0\
**Last updated:** [September 15, 2020, 7:53pm UTC](https://discourse.julialang.org/t/upwind-advection-scheme-with-periodic-boundary-conditions/46658 "2020-09-15T19:53:41Z")

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## [Cannot load SVG files with Gtk.jl](https://discourse.julialang.org/t/cannot-load-svg-files-with-gtk-jl/46655)

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**Author:** [@xor0110](https://discourse.julialang.org/u/xor0110)\
**Replies:** 0\
**Last updated:** [September 15, 2020, 7:03pm UTC](https://discourse.julialang.org/t/cannot-load-svg-files-with-gtk-jl/46655 "2020-09-15T19:03:14Z")

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When loading a svg image inside a GtkImage widget, I get a “missing image” icon. If I load the image from within a Glade UI I also get an error message. (julia:18273): Gtk-WARNING \*\*: 21:00:53.077: Could not load image …

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## [Optimizing concatenation of data from large number of files](https://discourse.julialang.org/t/optimizing-concatenation-of-data-from-large-number-of-files/46617)

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**Author:** [@lwhitefox](https://discourse.julialang.org/u/lwhitefox)\
**Replies:** 2\
**Last updated:** [September 15, 2020, 5:05pm UTC](https://discourse.julialang.org/t/optimizing-concatenation-of-data-from-large-number-of-files/46617 "2020-09-15T17:05:26Z")

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I am trying to create a large data array from data in many input files by reading in the individual data file arrays concatenating a subset of columns to generate a large, single array The problem is that it is blazin…

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## [TCN Temporal Convolutional Networks in Julia?](https://discourse.julialang.org/t/tcn-temporal-convolutional-networks-in-julia/46188)

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**Author:** [@compleat](https://discourse.julialang.org/u/compleat)\
**Replies:** 4\
**Last updated:** [September 15, 2020, 5:01pm UTC](https://discourse.julialang.org/t/tcn-temporal-convolutional-networks-in-julia/46188 "2020-09-15T17:01:30Z")

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TCN’s are hyped to be the best new approach in ML forecasting of Financial Time Series since LSTM, and have been claimed to be superior in performance and more efficient to compute. Has anyone managed to implement TCN’…

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## [ANN: Knet 1.4.0: accelerating CuArrays](https://discourse.julialang.org/t/ann-knet-1-4-0-accelerating-cuarrays/45206)

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**Author:** [@denizyuret](https://discourse.julialang.org/u/denizyuret)\
**Replies:** 26\
**Last updated:** [September 15, 2020, 4:15pm UTC](https://discourse.julialang.org/t/ann-knet-1-4-0-accelerating-cuarrays/45206 "2020-09-15T16:15:57Z")

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I just released Knet 1.4.0, a major refactoring of the code (lots of submodules) for future improvements without any current API effects (hopefully). My first goal for this release was to fully support CuArrays without …

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## [Coordinate transformation from three known points](https://discourse.julialang.org/t/coordinate-transformation-from-three-known-points/37153)

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**Author:** [@yakir12](https://discourse.julialang.org/u/yakir12)\
**Replies:** 18\
**Last updated:** [September 15, 2020, 4:07pm UTC](https://discourse.julialang.org/t/coordinate-transformation-from-three-known-points/37153 "2020-09-15T16:07:37Z")

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I have 3 coordinates, moving\_points. I know where each of these is supposed to really be, fixed\_points. I want to transform them (and many other coordinates) to these known locations (involving translation, rotation, but…

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## [Accessing multi-dimensional arrays in 1 go](https://discourse.julialang.org/t/accessing-multi-dimensional-arrays-in-1-go/46641)

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**Author:** [@danicaratelli](https://discourse.julialang.org/u/danicaratelli)\
**Replies:** 5\
**Last updated:** [September 15, 2020, 3:46pm UTC](https://discourse.julialang.org/t/accessing-multi-dimensional-arrays-in-1-go/46641 "2020-09-15T15:46:48Z")

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I am trying to figure out if there is an easy (and quick) way of accessing elements of a multi-dimensional array according to multi-dimensional array of indices. For example: A = reshape(1:8,2,2,2); indxs = repeat(\[1\],…

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## [ArgumentError: invalid argument #4 to LAPACK call](https://discourse.julialang.org/t/argumenterror-invalid-argument-4-to-lapack-call/46455)

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**Author:** [@PhillipBC](https://discourse.julialang.org/u/PhillipBC)\
**Replies:** 7\
**Last updated:** [September 15, 2020, 3:51pm UTC](https://discourse.julialang.org/t/argumenterror-invalid-argument-4-to-lapack-call/46455 "2020-09-15T15:51:02Z")

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This problem arose using Julia 1.4.2, and I then got version 1.5.1 and the problem is still there. If I create a matrix, then get its eigenvalues, then plot the eigenvalues, then get the eigenvalues again, I get the err…

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## [Confused by "unsatisfiable requirements"](https://discourse.julialang.org/t/confused-by-unsatisfiable-requirements/46564)

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**Author:** [@scheinerman](https://discourse.julialang.org/u/scheinerman)\
**Replies:** 10\
**Last updated:** [September 15, 2020, 2:59pm UTC](https://discourse.julialang.org/t/confused-by-unsatisfiable-requirements/46564 "2020-09-15T14:59:31Z")

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I have recently upgraded my package SimpleGraphs to version 0.6.1. Other packages that depend on it now can only be used in development mode. For example, my registered package SimpleGraphAlgorithms has this problem: (@…

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## [Examples with atomic operations using CUDA.jl](https://discourse.julialang.org/t/examples-with-atomic-operations-using-cuda-jl/46084)

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**Author:** [@duanestorti](https://discourse.julialang.org/u/duanestorti)\
**Replies:** 6\
**Last updated:** [September 15, 2020, 2:31pm UTC](https://discourse.julialang.org/t/examples-with-atomic-operations-using-cuda-jl/46084 "2020-09-15T14:31:44Z")

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Can anyone point me to examples that include atomic operations using CUDA.jl? I am having some issues trying to figure out the syntax for pointers, and examples would be helpful.

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## [Gtk standalone application (PackageCompiler) cannot open images](https://discourse.julialang.org/t/gtk-standalone-application-packagecompiler-cannot-open-images/46637)

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**Author:** [@xor0110](https://discourse.julialang.org/u/xor0110)\
**Replies:** 0\
**Last updated:** [September 15, 2020, 1:27pm UTC](https://discourse.julialang.org/t/gtk-standalone-application-packagecompiler-cannot-open-images/46637 "2020-09-15T13:27:48Z")

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I have this Gkt.jl application, and I’m trying to make it stand-alone with PackageCompiler. Right now most functionality seems to work, although I have this problem at startup, when I try to load some images, which do n…

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## [Performance of creating a tuple with a for loop](https://discourse.julialang.org/t/performance-of-creating-a-tuple-with-a-for-loop/46606)

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**Author:** [@dogiv](https://discourse.julialang.org/u/dogiv)\
**Replies:** 26\
**Last updated:** [September 15, 2020, 1:11pm UTC](https://discourse.julialang.org/t/performance-of-creating-a-tuple-with-a-for-loop/46606 "2020-09-15T13:11:33Z")

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I have a function “complement” that takes two tuples of ints and does a simple comparison to generate a third tuple. I would prefer to write it so that it works for any length of tuple, but that kills the performance (10…

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## [Could I use Python Dict or convert Julia Dict to Python Dict in Julia?](https://discourse.julialang.org/t/could-i-use-python-dict-or-convert-julia-dict-to-python-dict-in-julia/46632)

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**Author:** [@Ke\_Gao](https://discourse.julialang.org/u/Ke_Gao)\
**Replies:** 2\
**Last updated:** [September 15, 2020, 12:05pm UTC](https://discourse.julialang.org/t/could-i-use-python-dict-or-convert-julia-dict-to-python-dict-in-julia/46632 "2020-09-15T12:05:17Z")

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Hi, I am writing a piece of code that need to load a Python package with PyCall. But when I transfer a Julia Dict to the package, I got an error. I think it is because the package can not identify the Julia Dict, so I …

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## [Adjusting markers in legend](https://discourse.julialang.org/t/adjusting-markers-in-legend/38042)

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**Author:** [@jamblejoe](https://discourse.julialang.org/u/jamblejoe)\
**Replies:** 4\
**Last updated:** [September 15, 2020, 11:40am UTC](https://discourse.julialang.org/t/adjusting-markers-in-legend/38042 "2020-09-15T11:40:02Z")

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Hi, I would like to adjust marker settings in the legend, e.g. size and strokewidth, ideally with the pyplot backend. In the following minimal working example I would like the markers in the legend to be the same as in …

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## [Condition in @objective](https://discourse.julialang.org/t/condition-in-objective/46526)

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**Author:** [@sogrbilja](https://discourse.julialang.org/u/sogrbilja)\
**Replies:** 5\
**Last updated:** [September 15, 2020, 10:54am UTC](https://discourse.julialang.org/t/condition-in-objective/46526 "2020-09-15T10:54:45Z")

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I want to set an if statement in @objective macro. This is how it looks like now: @variable(premex, PRODAMOUNT\[op\_k in keys(\_ORDER\_PRODUCTs\_ALL), u\_k in keys(UNITS), t in TIME\], Int, lower\_bound = 0) @o…

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## [Zygote has a problem of derivation in the loss function](https://discourse.julialang.org/t/zygote-has-a-problem-of-derivation-in-the-loss-function/46627)

<div class="topic-metadata">

**Author:** [@doli](https://discourse.julialang.org/u/doli)\
**Replies:** 6\
**Last updated:** [September 15, 2020, 10:43am UTC](https://discourse.julialang.org/t/zygote-has-a-problem-of-derivation-in-the-loss-function/46627 "2020-09-15T10:43:02Z")

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I have a problem with Flux. Unfortunately Zygote cannot derive my loss function and I am not sure what it is. It would be nice if someone could help me with this problem. My loss function looks like this: function los…

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## [Zygote unexpected broadcasting](https://discourse.julialang.org/t/zygote-unexpected-broadcasting/46476)

<div class="topic-metadata">

**Author:** [@merckxiaan](https://discourse.julialang.org/u/merckxiaan)\
**Replies:** 1\
**Last updated:** [September 15, 2020, 9:47am UTC](https://discourse.julialang.org/t/zygote-unexpected-broadcasting/46476 "2020-09-15T09:47:48Z")

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This is a MWE for a problem i’m having, I’ve adapted matrix multiplication to accept trans arguments telling whether the matrix is to be transposed. As for the adjoint definition, I looked at NNlib.batched\_mul When I t…

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