# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=371

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**Page:** 372

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## [\[DifferentialEquations.jl\] Can't brodcast time gradients into dualcache](https://discourse.julialang.org/t/differentialequations-jl-cant-brodcast-time-gradients-into-dualcache/60007)

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**Author:** [@MatFi](https://discourse.julialang.org/u/MatFi)\
**Replies:** 4\
**Last updated:** [April 25, 2021, 10:05pm UTC](https://discourse.julialang.org/t/differentialequations-jl-cant-brodcast-time-gradients-into-dualcache/60007 "2021-04-25T22:05:38Z")

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I need to cache some data during the evaluation of an ODE. However the time gradients make it a bit difficult to me and cuse a MethodError. MWE using DiffEqBase, OrdinaryDiffEq struct rb{T} B::T end rb(n::Integer)…

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## [\`x==y\` is true but \`π^x == π^y\` is false](https://discourse.julialang.org/t/x-y-is-true-but-x-y-is-false/59976)

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**Author:** [@HJW019](https://discourse.julialang.org/u/HJW019)\
**Replies:** 8\
**Last updated:** [April 25, 2021, 5:58pm UTC](https://discourse.julialang.org/t/x-y-is-true-but-x-y-is-false/59976 "2021-04-25T17:58:25Z")

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A simple question for you CS experts: function foo() x::Float32 = 0.5 y::Float64 = 0.5 return x==y, π^x == π^y end julia\> foo() (true, false) Why x==y is true given the different numeric types? And if x==y …

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## [How to draw 2D text on top of a 3D figure with Makie](https://discourse.julialang.org/t/how-to-draw-2d-text-on-top-of-a-3d-figure-with-makie/59983)

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**Author:** [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Replies:** 4\
**Last updated:** [April 25, 2021, 4:43pm UTC](https://discourse.julialang.org/t/how-to-draw-2d-text-on-top-of-a-3d-figure-with-makie/59983 "2021-04-25T16:43:43Z")

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I have the following code: using GeometryBasics, GLMakie const SCALE = 1.2 const SEGMENTS = 7 # number of tether segments function create\_coordinate\_system(scene, points = 10, length = 10) # cre…

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## [Discretized HMC](https://discourse.julialang.org/t/discretized-hmc/59964)

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**Author:** [@ParadaCarleton](https://discourse.julialang.org/u/ParadaCarleton)\
**Replies:** 1\
**Last updated:** [April 25, 2021, 2:25pm UTC](https://discourse.julialang.org/t/discretized-hmc/59964 "2021-04-25T14:25:48Z")

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Is there any interest in implementing generalizations of HMC to discrete spaces for Turing.jl? Examples: https://www.tandfonline.com/doi/full/10.1080/01621459.2019.1585255?casa\_token=XuidyAblCZQAAAAA:FrOpfFdJWbBrG1R0-ZN…

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## [CUDA.jl tex2DLayered support?](https://discourse.julialang.org/t/cuda-jl-tex2dlayered-support/59625)

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**Author:** [@jpdoane](https://discourse.julialang.org/u/jpdoane)\
**Replies:** 2\
**Last updated:** [April 25, 2021, 1:25pm UTC](https://discourse.julialang.org/t/cuda-jl-tex2dlayered-support/59625 "2021-04-25T13:25:16Z")

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Is there a plan to integrate Layered Textures support into CUDA.jl? I am currently using a 3D texture for my application, but I suspect I am getting sub-optimal performance since my data structure really is a set of 2D …

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## [MakieGL fails after update](https://discourse.julialang.org/t/makiegl-fails-after-update/59978)

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**Author:** [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Replies:** 8\
**Last updated:** [April 25, 2021, 10:20am UTC](https://discourse.julialang.org/t/makiegl-fails-after-update/59978 "2021-04-25T10:20:23Z")

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I am using MakieGL on Ubuntu 18.04. It used to work fine, but after an update it doesn’t work any more. I updated: Julia to 1.6.1 MakieGL to latest stable version and Ubuntu updated the nvidea graphics drivers. The …

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## [Why is Optim.optimize() throwing an exception if I provide initial\_invH?](https://discourse.julialang.org/t/why-is-optim-optimize-throwing-an-exception-if-i-provide-initial-invh/59872)

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**Author:** [@marcus-waldman](https://discourse.julialang.org/u/marcus-waldman)\
**Replies:** 4\
**Last updated:** [April 25, 2021, 10:06am UTC](https://discourse.julialang.org/t/why-is-optim-optimize-throwing-an-exception-if-i-provide-initial-invh/59872 "2021-04-25T10:06:59Z")

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I’m trying to implement the EM algorithm to estimate parameters in a large model The EM algorithm requires a lot of back and forth updating some parameters of interest and then optimizing an objective function based on t…

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## [Problems with stiff solvers for MTK model](https://discourse.julialang.org/t/problems-with-stiff-solvers-for-mtk-model/59658)

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**Author:** [@ohmsweetohm1](https://discourse.julialang.org/u/ohmsweetohm1)\
**Replies:** 4\
**Last updated:** [April 25, 2021, 8:14am UTC](https://discourse.julialang.org/t/problems-with-stiff-solvers-for-mtk-model/59658 "2021-04-25T08:14:57Z")

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I have a MTK model (copy paste from docs): using ModelingToolkit, Plots, DifferentialEquations @parameters t function Pin(;name) @variables v(t) i(t) ODESystem(Equation\[\], t, \[v, i\], \[\], name=name, defaults=\[v…

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## [Error building \`Gurobi\`](https://discourse.julialang.org/t/error-building-gurobi/59852)

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**Author:** [@zlq178](https://discourse.julialang.org/u/zlq178)\
**Replies:** 6\
**Last updated:** [April 25, 2021, 7:38am UTC](https://discourse.julialang.org/t/error-building-gurobi/59852 "2021-04-25T07:38:00Z")

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I have installed Gurobi.jl(v"0.8.1"), When I build it, some wrong happened. Julia version:JuliaPro 1.5.1-1. What should I do next? Thank you for your help. julia\>ENV\["GUROBI\_HOME"\] = "C:\\\\gurobi911\\\\win64" julia\>import…

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## [Acausal modeling with ModelingToolkit.jl: Why does structural\_simplify not eliminate one more variable?](https://discourse.julialang.org/t/acausal-modeling-with-modelingtoolkit-jl-why-does-structural-simplify-not-eliminate-one-more-variable/59474)

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**Author:** [@frnkcg](https://discourse.julialang.org/u/frnkcg)\
**Replies:** 10\
**Last updated:** [April 25, 2021, 5:28am UTC](https://discourse.julialang.org/t/acausal-modeling-with-modelingtoolkit-jl-why-does-structural-simplify-not-eliminate-one-more-variable/59474 "2021-04-25T05:28:07Z")

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I know a little bit of Modelica so when I recently encountered ModelingToolkit.jl, I was excited to try it out. But I ran into some unexpected problems even for a very simple model. I created an acausal model of a simpl…

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## [Using a posterior from a previous sample as a prior](https://discourse.julialang.org/t/using-a-posterior-from-a-previous-sample-as-a-prior/59914)

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**Author:** [@pthompson234](https://discourse.julialang.org/u/pthompson234)\
**Replies:** 2\
**Last updated:** [April 25, 2021, 2:00am UTC](https://discourse.julialang.org/t/using-a-posterior-from-a-previous-sample-as-a-prior/59914 "2021-04-25T02:00:34Z")

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Sorry if this is a question that has already been asked, or if this is the wrong place for something like this - I’ve done a bit of searching and haven’t found anything that works for the Turing package. In short, what I…

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## [Why the dimension of V1 = ℤ₂Space(0=\>3,1=\>2) is 5?](https://discourse.julialang.org/t/why-the-dimension-of-v1-space-0-3-1-2-is-5/59960)

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**Author:** [@Nellatur](https://discourse.julialang.org/u/Nellatur)\
**Replies:** 0\
**Last updated:** [April 25, 2021, 12:29am UTC](https://discourse.julialang.org/t/why-the-dimension-of-v1-space-0-3-1-2-is-5/59960 "2021-04-25T00:29:48Z")

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I am not sure if this question would belong to mathematics or more suitable for mathematics stackexchange. It comes from https://jutho.github.io/TensorKit.jl/stable/man/tutorial/#Symmetries julia\> V1 = ℤ₂Space(0=\>3,1=\>2…

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## [Compute surfaces of intersection between circles in julia with LibGEOS](https://discourse.julialang.org/t/compute-surfaces-of-intersection-between-circles-in-julia-with-libgeos/59811)

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**Author:** [@Meije\_Gawinowski](https://discourse.julialang.org/u/Meije_Gawinowski)\
**Replies:** 4\
**Last updated:** [April 24, 2021, 12:55pm UTC](https://discourse.julialang.org/t/compute-surfaces-of-intersection-between-circles-in-julia-with-libgeos/59811 "2021-04-24T12:55:11Z")

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I need to compute surfaces of intersection between different circles. I am used to do it in R with the sf library and it works fine but I need to do it in Julia with the LibGEOS library and it is not as easy… My first q…

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## [Encryption/decryption package](https://discourse.julialang.org/t/encryption-decryption-package/59581)

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**Author:** [@Laco\_Kovac](https://discourse.julialang.org/u/Laco_Kovac)\
**Replies:** 9\
**Last updated:** [April 24, 2021, 10:40am UTC](https://discourse.julialang.org/t/encryption-decryption-package/59581 "2021-04-24T10:40:24Z")

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I have quite big String (~20M). It needs to be encrypted and downloaded as a file and then, eventually, uploaded back, decrypted & used. Encryption key or password belongs to the application/server (i.e. it is not specif…

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## [Filling Areas to Complete a ColorMap](https://discourse.julialang.org/t/filling-areas-to-complete-a-colormap/59851)

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**Author:** [@p.sms](https://discourse.julialang.org/u/p.sms)\
**Replies:** 3\
**Last updated:** [April 24, 2021, 5:39am UTC](https://discourse.julialang.org/t/filling-areas-to-complete-a-colormap/59851 "2021-04-24T05:39:28Z")

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Hello People, I am rather new to Julia so I would be very thankful if someone was able to help or guide me, I am trying to plot a 2D grid of 126 3-nodes triangular finite elements with color representing a main strain. …

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## [Should models revert to "unoptimized" if they are modified?](https://discourse.julialang.org/t/should-models-revert-to-unoptimized-if-they-are-modified/59627)

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**Author:** [@gleyland](https://discourse.julialang.org/u/gleyland)\
**Replies:** 4\
**Last updated:** [April 23, 2021, 9:22pm UTC](https://discourse.julialang.org/t/should-models-revert-to-unoptimized-if-they-are-modified/59627 "2021-04-23T21:22:05Z")

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If I optimize! a model with GLPK, then add a constraint, I can still access the solution: using JuMP, GLPK, Clp; M = Model(); @variable M A\[1:2\] \>= 0; @constraint M limit1 sum(a for a in A) \<= 1; @objective M Max sum(a …

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## [Calculating specific components of gradients](https://discourse.julialang.org/t/calculating-specific-components-of-gradients/59733)

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**Author:** [@schaerfo](https://discourse.julialang.org/u/schaerfo)\
**Replies:** 4\
**Last updated:** [April 23, 2021, 7:10pm UTC](https://discourse.julialang.org/t/calculating-specific-components-of-gradients/59733 "2021-04-23T19:10:17Z")

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Occasionally, I work with scalar-valued functions that take multiple vectors as arguments. A simple example is: f(\\mathbf{x}, \\mathbf{y}) = e^{-|\\mathbf{x}-\\mathbf{y}|^2} In Julia, this can be coded as: f(x, y) = exp…

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## [How to get row indices and how can I change row indices/row names in a Julia DataFrame?](https://discourse.julialang.org/t/how-to-get-row-indices-and-how-can-i-change-row-indices-row-names-in-a-julia-dataframe/59884)

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**Author:** [@shubh\_b](https://discourse.julialang.org/u/shubh_b)\
**Replies:** 7\
**Last updated:** [April 23, 2021, 5:06pm UTC](https://discourse.julialang.org/t/how-to-get-row-indices-and-how-can-i-change-row-indices-row-names-in-a-julia-dataframe/59884 "2021-04-23T17:06:21Z")

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If I take a Julia DataFrame as below julia\> using DataFrames julia\> df = DataFrame(col1 = \['α', 'β', 'γ'\], col2 = \['A', 'B', 'C'\]) 3×2 DataFrame │ Row │ col1 │ col2 │ │ │ Char │ Char │ ├─────┼──────┼──────┤ │ 1 │ …

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## [Accessing array elements too slow?](https://discourse.julialang.org/t/accessing-array-elements-too-slow/59856)

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**Author:** [@Ferran\_Mazzanti](https://discourse.julialang.org/u/Ferran_Mazzanti)\
**Replies:** 10\
**Last updated:** [April 23, 2021, 3:54pm UTC](https://discourse.julialang.org/t/accessing-array-elements-too-slow/59856 "2021-04-23T15:54:24Z")

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Hi, I think I could use some help here… As a part of a Monte Carlo code I’m developing in julia+CUDA, I have a function that takes several input parameters, performs a calculation with them, and stores the result in a C…

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## [Simple Parallel Examples for Embarrassingly Simple Problems](https://discourse.julialang.org/t/simple-parallel-examples-for-embarrassingly-simple-problems/8788)

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**Author:** [@ivo\_welch](https://discourse.julialang.org/u/ivo_welch)\
**Replies:** 29\
**Last updated:** [April 23, 2021, 3:45pm UTC](https://discourse.julialang.org/t/simple-parallel-examples-for-embarrassingly-simple-problems/8788 "2021-04-23T15:45:18Z")

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macOS, julia 0.6.2, Feb 2018, captain’s log: I have been playing around with trying to understand (the docs on) parallelism. as an early example, I just want to create, in parallel, a list of function logp1(x::Int64):…

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## [Multiple CPU threads that use Unified Memory gives a Bus Error](https://discourse.julialang.org/t/multiple-cpu-threads-that-use-unified-memory-gives-a-bus-error/59814)

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**Author:** [@barrettp](https://discourse.julialang.org/u/barrettp)\
**Replies:** 5\
**Last updated:** [April 23, 2021, 2:03pm UTC](https://discourse.julialang.org/t/multiple-cpu-threads-that-use-unified-memory-gives-a-bus-error/59814 "2021-04-23T14:03:20Z")

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I’ve have a function that calls a kernel that uses unified memory. The function allocates and frees the unified memory before and after multiple kernel invocations. I call synchronize() after each kernel call. Without sy…

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## [Makie - 3D volume rendering - using Axis3 - questions/issues](https://discourse.julialang.org/t/makie-3d-volume-rendering-using-axis3-questions-issues/59615)

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**Author:** [@Audrius-St](https://discourse.julialang.org/u/Audrius-St)\
**Replies:** 14\
**Last updated:** [April 22, 2021, 7:56pm UTC](https://discourse.julialang.org/t/makie-3d-volume-rendering-using-axis3-questions-issues/59615 "2021-04-22T19:56:52Z")

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Hello, this is my first go at using Julia and GLMakie. The goal is to display a 3D MIP CT image extracted from DICOM data. Julia 1.6 DICOM v0.10.0 AbstractPlotting v0.17.3 GLMakie v0.2.6 Windows 10 x64 Visual Stu…

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## [Handling color in Plots user recipe that produces an image, or indexed color](https://discourse.julialang.org/t/handling-color-in-plots-user-recipe-that-produces-an-image-or-indexed-color/59769)

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**Author:** [@goretkin](https://discourse.julialang.org/u/goretkin)\
**Replies:** 2\
**Last updated:** [April 22, 2021, 11:46pm UTC](https://discourse.julialang.org/t/handling-color-in-plots-user-recipe-that-produces-an-image-or-indexed-color/59769 "2021-04-22T23:46:41Z")

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I have a Grid type, and I have a way to plot it in terms of an image (Array{RBGA{...}, 2}), so I define the following user recipe: using Plots using Plots: RGBA using RecipesBase using OffsetArrays struct Grid x::O…

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## [AMPL to jump](https://discourse.julialang.org/t/ampl-to-jump/56760)

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**Author:** [@aaldik](https://discourse.julialang.org/u/aaldik)\
**Replies:** 4\
**Last updated:** [April 22, 2021, 7:31pm UTC](https://discourse.julialang.org/t/ampl-to-jump/56760 "2021-04-22T19:31:29Z")

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Dears I have a question regarding solving a problem that was written in AMPL using Jump. Is there a specific function that allows for translating an ampl file into a recognized file by jump? what is the most efficient w…

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## [Triangular Schur decomposition for a matrix with complex eigenvalues?](https://discourse.julialang.org/t/triangular-schur-decomposition-for-a-matrix-with-complex-eigenvalues/25680)

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**Author:** [@zdenek\_hurak](https://discourse.julialang.org/u/zdenek_hurak)\
**Replies:** 5\
**Last updated:** [April 22, 2021, 6:57pm UTC](https://discourse.julialang.org/t/triangular-schur-decomposition-for-a-matrix-with-complex-eigenvalues/25680 "2021-04-22T18:57:16Z")

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Is it possible to compute a (strictly) triangular Schur decomposition for a matrix with complex eigenvalues? With the code below I create such a matrix: T = rand(2,2) λ = rand() + rand()\*im D = \[real(λ) imag(λ); -imag(…

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## [Filter design: MATLAB firls (Least-squares linear-phase FIR filter design) alternative?](https://discourse.julialang.org/t/filter-design-matlab-firls-least-squares-linear-phase-fir-filter-design-alternative/45249)

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**Author:** [@ElectronicTeaCup](https://discourse.julialang.org/u/ElectronicTeaCup)\
**Replies:** 17\
**Last updated:** [April 22, 2021, 6:49pm UTC](https://discourse.julialang.org/t/filter-design-matlab-firls-least-squares-linear-phase-fir-filter-design-alternative/45249 "2021-04-22T18:49:53Z")

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Hi! I am going through a MATLAB based textbook for time frequency analysis of Neural data (MEG/EEG time series data) and got to a chapter which goes through filter construction. It’s primarily going over the usage of the…

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## [RNN is not trained](https://discourse.julialang.org/t/rnn-is-not-trained/59553)

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**Author:** [@Sunny](https://discourse.julialang.org/u/Sunny)\
**Replies:** 6\
**Last updated:** [April 22, 2021, 5:31pm UTC](https://discourse.julialang.org/t/rnn-is-not-trained/59553 "2021-04-22T17:31:10Z")

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I’m trying to reproduce this example but my model won’t train. I use only train dataset to achieve overfitting and get just a line as prediction: using Pandas using Plots using Flux df = read\_csv("airline-passengers.c…

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## [PDE Errors](https://discourse.julialang.org/t/pde-errors/59707)

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**Author:** [@Ian\_Slagle](https://discourse.julialang.org/u/Ian_Slagle)\
**Replies:** 6\
**Last updated:** [April 22, 2021, 4:36pm UTC](https://discourse.julialang.org/t/pde-errors/59707 "2021-04-22T16:36:34Z")

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I am trying to reproduce this solution to a PDE (Mathematica code located beneath tweet). https://twitter.com/matthen2/status/1378820454589292550?s=21 This is my attempt thus far. Note that with my domains I actually h…

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## [Is there an easy way to convert all data in DataFrame (or Matrix) to INT?](https://discourse.julialang.org/t/is-there-an-easy-way-to-convert-all-data-in-dataframe-or-matrix-to-int/59804)

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**Author:** [@Igor\_Douven](https://discourse.julialang.org/u/Igor_Douven)\
**Replies:** 5\
**Last updated:** [April 22, 2021, 3:58pm UTC](https://discourse.julialang.org/t/is-there-an-easy-way-to-convert-all-data-in-dataframe-or-matrix-to-int/59804 "2021-04-22T15:58:54Z")

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Hi all, I’m trying to import a .csv file with missing values (just blanks, in the file). I’m using CSV.jl together with DataFrames.jl for this. I notice that the columns containing a missing value are all of type String …

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## [Rasterizing feature data](https://discourse.julialang.org/t/rasterizing-feature-data/59594)

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**Author:** [@mihalybaci](https://discourse.julialang.org/u/mihalybaci)\
**Replies:** 17\
**Last updated:** [April 22, 2021, 12:27pm UTC](https://discourse.julialang.org/t/rasterizing-feature-data/59594 "2021-04-22T12:27:18Z")

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I have a set of WKT strings that I would like to convert into 256x256 raster images (masks, really). I read them into geometries (specifically, multipolygons) just fine with ArchGDAL.fomWKT, but ArchGDAL.unsafe\_rasterize …

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