# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=353

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**Page:** 354

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## [Accessing a specific layer's weights in a Flux Chain](https://discourse.julialang.org/t/accessing-a-specific-layers-weights-in-a-flux-chain/64180)

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**Author:** [@bad\_at\_math](https://discourse.julialang.org/u/bad_at_math)\
**Replies:** 1\
**Last updated:** [July 7, 2021, 1:15am UTC](https://discourse.julialang.org/t/accessing-a-specific-layers-weights-in-a-flux-chain/64180 "2021-07-07T01:15:44Z")

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In PyTorch, I can define a network like this: from torch import nn class Network(nn.Module): def \_\_init\_\_(self, ...): ... self.ln\_1 = nn.Linear(64, 32) self.ln\_2 = nn.Linear(32, 16) …

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## [Performance overhead observed variables ModelingToolkit](https://discourse.julialang.org/t/performance-overhead-observed-variables-modelingtoolkit/64164)

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**Author:** [@Elmo](https://discourse.julialang.org/u/Elmo)\
**Replies:** 1\
**Last updated:** [July 6, 2021, 9:43pm UTC](https://discourse.julialang.org/t/performance-overhead-observed-variables-modelingtoolkit/64164 "2021-07-06T21:43:51Z")

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Hi all, I am using ModelingToolkit to simulate a system and noticed that there seems to be a serious performance cost associated with using the nice observed variables functionality of ModelingToolkit. Here is a minimal …

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## [Memory Allocation JuMP constraint!](https://discourse.julialang.org/t/memory-allocation-jump-constraint/64137)

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**Author:** [@musman](https://discourse.julialang.org/u/musman)\
**Replies:** 1\
**Last updated:** [July 6, 2021, 9:25pm UTC](https://discourse.julialang.org/t/memory-allocation-jump-constraint/64137 "2021-07-06T21:25:42Z")

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Hi all, I am implementing the following constraint which is allocating around 27MB of memory. for i in 1:nLines f\_bus = nw\_lines\[i\].line\_from t\_bus = nw\_lines\[i\].line\_to idx\_t\_bus = findall(x-\>x==t\_…

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## [ODE solver fails with ForwardDiff, but works with central differences for first derivative of an input function](https://discourse.julialang.org/t/ode-solver-fails-with-forwarddiff-but-works-with-central-differences-for-first-derivative-of-an-input-function/63033)

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**Author:** [@TS-CUBED](https://discourse.julialang.org/u/TS-CUBED)\
**Replies:** 10\
**Last updated:** [July 6, 2021, 9:17pm UTC](https://discourse.julialang.org/t/ode-solver-fails-with-forwarddiff-but-works-with-central-differences-for-first-derivative-of-an-input-function/63033 "2021-07-06T21:17:35Z")

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I am modelling the human cardiovascular system and solve equations similar to the windkessel equation in the example: # The 5-element WK formulation, also 4-element parallel for Ls = 0.0 function wk5(dP,…

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## [Turing model that records objective function values](https://discourse.julialang.org/t/turing-model-that-records-objective-function-values/64167)

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**Author:** [@pthompson234](https://discourse.julialang.org/u/pthompson234)\
**Replies:** 0\
**Last updated:** [July 6, 2021, 6:22pm UTC](https://discourse.julialang.org/t/turing-model-that-records-objective-function-values/64167 "2021-07-06T18:22:17Z")

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Hi, this might be a bit of a silly question but I’m using Turing to run a Bayesian MCMC algorithm. I’m using a distribution I made up as the distribution of my response variable and I would like the chain object to store…

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## [IntervalOptimisation surprising result](https://discourse.julialang.org/t/intervaloptimisation-surprising-result/64144)

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**Author:** [@gmouts](https://discourse.julialang.org/u/gmouts)\
**Replies:** 9\
**Last updated:** [July 6, 2021, 6:11pm UTC](https://discourse.julialang.org/t/intervaloptimisation-surprising-result/64144 "2021-07-06T18:11:08Z")

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I need to find the maximiser and the maximum of functions that have a narrow bump. I had some issues with numerics, so I decided to try my luck with intervals. Here is a minimal working (?) example: using IntervalArith…

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## [Memory allocation problem with Optim + ApproxFun](https://discourse.julialang.org/t/memory-allocation-problem-with-optim-approxfun/64084)

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**Author:** [@dbennett1994](https://discourse.julialang.org/u/dbennett1994)\
**Replies:** 8\
**Last updated:** [July 6, 2021, 2:06pm UTC](https://discourse.julialang.org/t/memory-allocation-problem-with-optim-approxfun/64084 "2021-07-06T14:06:09Z")

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Hi all. I’m quite new to Julia and this is my first post. I want to optimize a functional F\[\\phi\] = \\int\_0^1 \\left\[\\frac{1}{2}\\left(\\partial\_x \\phi\\right)^2 + V(x,\\phi(x))\\right\]\\text{d}x. Of course, this can be done by…

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## [Reseting Device](https://discourse.julialang.org/t/reseting-device/63997)

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**Author:** [@Fabrice\_Rosay](https://discourse.julialang.org/u/Fabrice_Rosay)\
**Replies:** 20\
**Last updated:** [July 6, 2021, 12:30pm UTC](https://discourse.julialang.org/t/reseting-device/63997 "2021-07-06T12:30:33Z")

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Is there any way to reset device state, or at least wipe memory allocated, but keeping already compiled kernel ? I keep seeing slow down during iterated call to CUDA and those disapear if i stop and rerun the execution.…

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## [Developing a Beginner's Roadmap to Learn Julia High Performance Computing for Data Science](https://discourse.julialang.org/t/developing-a-beginners-roadmap-to-learn-julia-high-performance-computing-for-data-science/63970)

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**Author:** [@TheCedarPrince](https://discourse.julialang.org/u/TheCedarPrince)\
**Replies:** 30\
**Last updated:** [July 5, 2021, 11:53pm UTC](https://discourse.julialang.org/t/developing-a-beginners-roadmap-to-learn-julia-high-performance-computing-for-data-science/63970 "2021-07-05T23:53:19Z")

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Hi all :wave: Hope you are doing well! In alignment with both my professional and personal interests, I am slowly starting to turn my attention to the domain of High Performance Computing for the purposes of: Designin…

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## [Learning Epidemic Model With Neural Differential Equations](https://discourse.julialang.org/t/learning-epidemic-model-with-neural-differential-equations/63386)

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**Author:** [@bkuwahara](https://discourse.julialang.org/u/bkuwahara)\
**Replies:** 5\
**Last updated:** [July 5, 2021, 9:26pm UTC](https://discourse.julialang.org/t/learning-epidemic-model-with-neural-differential-equations/63386 "2021-07-05T21:26:22Z")

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I’m trying to use neural networks with DiffEqFlux to learn an SIR model with vaccination dynamics. The equations for this model are function SIRx!(du, u, p, t) β, μ, γ, a, b = Float32.(\[280, 1/50, 365/22, 100, 0.05\]…

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## [Using casadi from Julia](https://discourse.julialang.org/t/using-casadi-from-julia/63988)

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**Author:** [@adityac](https://discourse.julialang.org/u/adityac)\
**Replies:** 11\
**Last updated:** [July 5, 2021, 2:47am UTC](https://discourse.julialang.org/t/using-casadi-from-julia/63988 "2021-07-05T02:47:25Z")

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I am trying to use Casadi from Julia using the opti stack. I am trying to do this using PyCall. I get an error when I use the following code: opti = casadi.Opti(); x = opti.variable(); y = opti.variable(); opti.minimi…

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## [\`CUDA.quicksort\` is not faster than CPU radixsort](https://discourse.julialang.org/t/cuda-quicksort-is-not-faster-than-cpu-radixsort/64036)

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**Author:** [@xiaodai](https://discourse.julialang.org/u/xiaodai)\
**Replies:** 3\
**Last updated:** [July 4, 2021, 7:53pm UTC](https://discourse.julialang.org/t/cuda-quicksort-is-not-faster-than-cpu-radixsort/64036 "2021-07-04T19:53:08Z")

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Here’s my testing code using SortingAlgorithms a32 = rand(Float32, 10\_000\_000) @benchmark sort($a32, alg=RadixSort) using CUDA cua32 = cu(a32) @benchmark CUDA.@sync sort($cua32) So the on my GPU which is RT…

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## [Gnuplot.jl + Windows 10: mouse can't zoom in/out](https://discourse.julialang.org/t/gnuplot-jl-windows-10-mouse-cant-zoom-in-out/64038)

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**Author:** [@Inna](https://discourse.julialang.org/u/Inna)\
**Replies:** 4\
**Last updated:** [July 4, 2021, 6:31pm UTC](https://discourse.julialang.org/t/gnuplot-jl-windows-10-mouse-cant-zoom-in-out/64038 "2021-07-04T18:31:04Z")

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Dear all, I have Windows 10 64-bit, gnuplot Version 5.4 patchlevel 1 (terminal qt) and Julia 1.6.1 with Gnuplot.jl v1.4.0 . When i use gnuplot without julia: gnuplot\> plot sin(x) i get the plot fine. Mouse can zoom …

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## [Makie: Płot a number line](https://discourse.julialang.org/t/makie-plot-a-number-line/64032)

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**Author:** [@mschauer](https://discourse.julialang.org/u/mschauer)\
**Replies:** 1\
**Last updated:** [July 4, 2021, 2:10pm UTC](https://discourse.julialang.org/t/makie-plot-a-number-line/64032 "2021-07-04T14:10:47Z")

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I just need a number line, like so Can I free that from the Axis object?

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## [\[ANN\]: Announcing RxNav.jl interface to National Library of Medicine RxNav database](https://discourse.julialang.org/t/ann-announcing-rxnav-jl-interface-to-national-library-of-medicine-rxnav-database/64020)

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**Author:** [@wherrera](https://discourse.julialang.org/u/wherrera)\
**Replies:** 0\
**Last updated:** [July 4, 2021, 5:27am UTC](https://discourse.julialang.org/t/ann-announcing-rxnav-jl-interface-to-national-library-of-medicine-rxnav-database/64020 "2021-07-04T05:27:18Z")

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and

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## [Learning and benchmarking resources](https://discourse.julialang.org/t/learning-and-benchmarking-resources/64018)

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**Author:** [@johnh](https://discourse.julialang.org/u/johnh)\
**Replies:** 0\
**Last updated:** [July 4, 2021, 4:16am UTC](https://discourse.julialang.org/t/learning-and-benchmarking-resources/64018 "2021-07-04T04:16:30Z")

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I saw a post in the Data domain saying it was hard to get resources to learn MPI programming. First off I am not promoting the company I work for (Dell). I like to connect people and to inspire people with possibilities …

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## [ReinforcementLearning.jl I'm lost .. trying to implement an HVAC time to start system](https://discourse.julialang.org/t/reinforcementlearning-jl-im-lost-trying-to-implement-an-hvac-time-to-start-system/63941)

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**Author:** [@mackyo123](https://discourse.julialang.org/u/mackyo123)\
**Replies:** 7\
**Last updated:** [July 4, 2021, 1:31am UTC](https://discourse.julialang.org/t/reinforcementlearning-jl-im-lost-trying-to-implement-an-hvac-time-to-start-system/63941 "2021-07-04T01:31:48Z")

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I’m trying to figure out how to read in data from an HVAC system with 75 units with Zone Temperature (What the temperature is now) , Set Point(What the temperature needs to be at start time), Minutes till start time from…

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## [SCIP solver presolve](https://discourse.julialang.org/t/scip-solver-presolve/63946)

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**Author:** [@mjanun](https://discourse.julialang.org/u/mjanun)\
**Replies:** 2\
**Last updated:** [July 3, 2021, 11:34pm UTC](https://discourse.julialang.org/t/scip-solver-presolve/63946 "2021-07-03T23:34:25Z")

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SCIP presolve incorrectly returns some MILP and MINLP problems as infeasible or it gets stuck on presolving. I am trying to turn off presolve, but I am not sure which parameter to use. I have tried concurrent\_presolvebef…

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## [CUDA.rand() returns duplicate columns](https://discourse.julialang.org/t/cuda-rand-returns-duplicate-columns/63993)

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**Author:** [@jpdoane](https://discourse.julialang.org/u/jpdoane)\
**Replies:** 2\
**Last updated:** [July 3, 2021, 8:51pm UTC](https://discourse.julialang.org/t/cuda-rand-returns-duplicate-columns/63993 "2021-07-03T20:51:34Z")

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CUDA.rand() appears to return duplicate columns of complex numbers: julia\> CUDA.rand(ComplexF32, 512, 3) 512×3 CuArray{ComplexF32, 2}: 0.831271+0.460309im 0.831271+0.460309im 0.831271+0.460309im 0.0160654+0.0647…

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## [HPV disease model estimation (beginner issue)](https://discourse.julialang.org/t/hpv-disease-model-estimation-beginner-issue/63981)

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**Author:** [@Mevlut\_Cayli](https://discourse.julialang.org/u/Mevlut_Cayli)\
**Replies:** 2\
**Last updated:** [July 3, 2021, 8:41pm UTC](https://discourse.julialang.org/t/hpv-disease-model-estimation-beginner-issue/63981 "2021-07-03T20:41:21Z")

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\`Hi, I 'm trying to estimate HPV model parameters with Turing but I’m not sure about how to determine prior parameters especially with σ , so when I run the model it seems because of the bad selection of σ last parameter…

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## [Solving two sparse linear systems one is the transpose of the other](https://discourse.julialang.org/t/solving-two-sparse-linear-systems-one-is-the-transpose-of-the-other/63984)

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**Author:** [@Mohamed\_AbdElrahman](https://discourse.julialang.org/u/Mohamed_AbdElrahman)\
**Replies:** 2\
**Last updated:** [July 3, 2021, 7:02pm UTC](https://discourse.julialang.org/t/solving-two-sparse-linear-systems-one-is-the-transpose-of-the-other/63984 "2021-07-03T19:02:59Z")

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I’m solving two sparse linear systems (A^T) \* x\_1 = b\_1 and A \* x\_2 = b\_2. where A^T is the transpose of A and b\_1, b\_2 are different. With a direct LU solver. How can I factorize once and use it to solve the two li…

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## [Status of math intrinsics](https://discourse.julialang.org/t/status-of-math-intrinsics/63990)

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**Author:** [@shiroghost](https://discourse.julialang.org/u/shiroghost)\
**Replies:** 1\
**Last updated:** [July 3, 2021, 3:35pm UTC](https://discourse.julialang.org/t/status-of-math-intrinsics/63990 "2021-07-03T15:35:29Z")

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Hi all, I would like to understand what is the status of math functions in CUDA.jl. In particular: Is it neccesary to write CUDA.sin? It looks to me that this calls are converted automatically when code is executed on…

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## [Linear regression Gibbs sampler](https://discourse.julialang.org/t/linear-regression-gibbs-sampler/62817)

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**Author:** [@jzr](https://discourse.julialang.org/u/jzr)\
**Replies:** 2\
**Last updated:** [July 3, 2021, 11:06am UTC](https://discourse.julialang.org/t/linear-regression-gibbs-sampler/62817 "2021-07-03T11:06:53Z")

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I tried to copy this Python sampler Gibbs sampling for Bayesian linear regression in Python | Kieran R Campbell - blog but my Julia implementation returns unexpected numbers. What am I doing wrong? using Distributions…

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## [Modelling and Simulation: Regarding DDEs](https://discourse.julialang.org/t/modelling-and-simulation-regarding-ddes/63677)

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**Author:** [@Phonindra](https://discourse.julialang.org/u/Phonindra)\
**Replies:** 19\
**Last updated:** [July 2, 2021, 10:43pm UTC](https://discourse.julialang.org/t/modelling-and-simulation-regarding-ddes/63677 "2021-07-02T22:43:13Z")

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I was facing a problem regarding delay. For low delay e.g. tau = 0.101 the code was fine as tau increases slightly as tau = 0.104 or more it shows some error not exactly error but warning and shows no promising result. W…

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## [Training an Autoencoder with Flux](https://discourse.julialang.org/t/training-an-autoencoder-with-flux/51619)

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**Author:** [@Geoffrey](https://discourse.julialang.org/u/Geoffrey)\
**Replies:** 2\
**Last updated:** [July 2, 2021, 6:12pm UTC](https://discourse.julialang.org/t/training-an-autoencoder-with-flux/51619 "2021-07-02T18:12:28Z")

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Hi, I’m trying to train a simple Autoencoder with the objective of using it for data imputation. The idea is that I have matrix of count with zeros values that are caused by a lack of sensitivity of the detector and wan…

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## [MCMC landscape](https://discourse.julialang.org/t/mcmc-landscape/25654)

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**Author:** [@davidanthoff](https://discourse.julialang.org/u/davidanthoff)\
**Replies:** 99\
**Last updated:** [July 2, 2021, 4:04pm UTC](https://discourse.julialang.org/t/mcmc-landscape/25654 "2021-07-02T16:04:16Z")

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We have been using Klara.jl for some of our projects, and are looking for alternatives (due to that package no longer being maintained). My sense is that Mamba.jl, Turing.jl and DynamicHMC.jl are the actively maintained…

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## [(seems) a more efficient way to use diffEqOperator.jl](https://discourse.julialang.org/t/seems-a-more-efficient-way-to-use-diffeqoperator-jl/63506)

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**Author:** [@Fred\_He](https://discourse.julialang.org/u/Fred_He)\
**Replies:** 5\
**Last updated:** [July 2, 2021, 12:12pm UTC](https://discourse.julialang.org/t/seems-a-more-efficient-way-to-use-diffeqoperator-jl/63506 "2021-07-02T12:12:04Z")

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I found the derivative operators are not efficient, there seems to have a more efficient way to use. If I am wrong please tell me. For example when I have : dx = 0.01 x = dx:dx:0.3 Δ1 = UpwindDifference(1, 1, dx, lengt…

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## [Drawing and animation, package recommendation](https://discourse.julialang.org/t/drawing-and-animation-package-recommendation/63917)

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**Author:** [@Erasmo98](https://discourse.julialang.org/u/Erasmo98)\
**Replies:** 5\
**Last updated:** [July 2, 2021, 9:30am UTC](https://discourse.julialang.org/t/drawing-and-animation-package-recommendation/63917 "2021-07-02T09:30:49Z")

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A friend of mine made this awsome image by hand using Windows Paint. Which package do you recommend me for drawing it and animating it? The animation would be of transformations of the original image. I’ve read that Cair…

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## [Two Decimal Place Fixed Point Decimals a Necessary Feature](https://discourse.julialang.org/t/two-decimal-place-fixed-point-decimals-a-necessary-feature/63808)

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**Author:** [@brett\_knoss](https://discourse.julialang.org/u/brett_knoss)\
**Replies:** 18\
**Last updated:** [July 2, 2021, 8:56am UTC](https://discourse.julialang.org/t/two-decimal-place-fixed-point-decimals-a-necessary-feature/63808 "2021-07-02T08:56:20Z")

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For basic accounting in all countries that use a decimal currency, such as Dollars and Cents, all numbers are always two decimal places. For this reason, having a financial number type, that is always two decimals, woul…

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## [Controling the shadows in 3D Makie visualizations](https://discourse.julialang.org/t/controling-the-shadows-in-3d-makie-visualizations/62796)

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**Author:** [@juliohm](https://discourse.julialang.org/u/juliohm)\
**Replies:** 7\
**Last updated:** [July 2, 2021, 8:46am UTC](https://discourse.julialang.org/t/controling-the-shadows-in-3d-makie-visualizations/62796 "2021-07-02T08:46:17Z")

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I am new to 3D visualization, and wonder how people usually control the “shadows”. When I visualize the grid below the colors are too dark as if the light source was behind the cube by default: Is there a recommended …

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