# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?page=502

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**Page:** 503

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## [Continuous relative/absolute residual](https://discourse.julialang.org/t/continuous-relative-absolute-residual/22949)

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**Author:** [@Tamas\_Papp](https://discourse.julialang.org/u/Tamas_Papp)\
**Replies:** 9\
**Last updated:** [April 9, 2019, 1:33pm UTC](https://discourse.julialang.org/t/continuous-relative-absolute-residual/22949 "2019-04-09T13:33:03Z")

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This is, strictly speaking, not a Julia but a math question, but I am running into this with AD and optimization. I am solving a parametric system f(x, \\theta) = g(x, \\theta) for x given \\theta. I could implement thi…

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## [Pyplot: how to change the marker color in a plot?](https://discourse.julialang.org/t/pyplot-how-to-change-the-marker-color-in-a-plot/22599)

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**Author:** [@ale](https://discourse.julialang.org/u/ale)\
**Replies:** 3\
**Last updated:** [April 7, 2019, 5:28pm UTC](https://discourse.julialang.org/t/pyplot-how-to-change-the-marker-color-in-a-plot/22599 "2019-04-07T17:28:19Z")

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Hi, I am trying to plot two curves in the same plot by using pyplot. I would appreciate if the 2 different curves had different colors. When it comes to the line, I managed to change it from the default blue color to e…

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## [Unravelling 'nativized' xml to readable string format](https://discourse.julialang.org/t/unravelling-nativized-xml-to-readable-string-format/22869)

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**Author:** [@hustf](https://discourse.julialang.org/u/hustf)\
**Replies:** 2\
**Last updated:** [April 7, 2019, 5:25pm UTC](https://discourse.julialang.org/t/unravelling-nativized-xml-to-readable-string-format/22869 "2019-04-07T17:25:11Z")

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I hope for ideas or help for unravelling some probably simple obfuscation of xml files. This requires some string work intuition, and I’m just stuck. Background: Mathcad is one of those classic engineering tools we lov…

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## [pycall matplotlib non-blocking plot?](https://discourse.julialang.org/t/pycall-matplotlib-non-blocking-plot/22876)

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**Author:** [@KestutisMa](https://discourse.julialang.org/u/KestutisMa)\
**Replies:** 3\
**Last updated:** [April 7, 2019, 5:08pm UTC](https://discourse.julialang.org/t/pycall-matplotlib-non-blocking-plot/22876 "2019-04-07T17:08:21Z")

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Hello, I am wondering how to do non-blocking plot: using PyCall; plt = pyimport("matplotlib.pyplot"); plt.plot(\[1,2\]); plt.show() shows plot window, but Julia is blocked, till I close plot window; plt.show(block = fals…

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## [Deval in solve](https://discourse.julialang.org/t/deval-in-solve/22873)

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**Author:** [@11110](https://discourse.julialang.org/u/11110)\
**Replies:** 1\
**Last updated:** [April 7, 2019, 2:45pm UTC](https://discourse.julialang.org/t/deval-in-solve/22873 "2019-04-07T14:45:04Z")

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Hello everyone! Is there a function similar to the one from Matlab deval in Julia? the deval function allows to find the value of the obtained solution trajectory at any point of the specified time interval after the pr…

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## [How to define state-dependent delay in delayed differential equations solver in Julia?](https://discourse.julialang.org/t/how-to-define-state-dependent-delay-in-delayed-differential-equations-solver-in-julia/18007)

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**Author:** [@PeterXG](https://discourse.julialang.org/u/PeterXG)\
**Replies:** 1\
**Last updated:** [November 27, 2018, 7:34am UTC](https://discourse.julialang.org/t/how-to-define-state-dependent-delay-in-delayed-differential-equations-solver-in-julia/18007 "2018-11-27T07:34:20Z")

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Dear All, I’m transferring from Matlab to Julia to solve delayed differential equations. I read documentation and notice it says define state-dependent delay by prob = DDEProblem(bc\_model,u0,h,tspan; dependent\_lags = …

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## [Defining custom matrix-free operators for solving a system of equations in iterativesolvers.jl](https://discourse.julialang.org/t/defining-custom-matrix-free-operators-for-solving-a-system-of-equations-in-iterativesolvers-jl/21150)

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**Author:** [@thehalfspace](https://discourse.julialang.org/u/thehalfspace)\
**Replies:** 5\
**Last updated:** [April 7, 2019, 10:20am UTC](https://discourse.julialang.org/t/defining-custom-matrix-free-operators-for-solving-a-system-of-equations-in-iterativesolvers-jl/21150 "2019-04-07T10:20:25Z")

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I am solving elastodynamic+elastostatic equations for waves and fracture using a spectral element method in 2D. One of the steps involves solving a large system of equations. I am currently using a preconditioned conjug…

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## [Steps to create additional table on matrix](https://discourse.julialang.org/t/steps-to-create-additional-table-on-matrix/22834)

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**Author:** [@WILSON\_MASIH](https://discourse.julialang.org/u/WILSON_MASIH)\
**Replies:** 4\
**Last updated:** [April 6, 2019, 8:57pm UTC](https://discourse.julialang.org/t/steps-to-create-additional-table-on-matrix/22834 "2019-04-06T20:57:47Z")

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A=zeros(5,5) # it represent 5x5 matrix having 0 number for i in 1:5 for j in 1:5 A\[i,j\]=i+j # square bracket for indices.as indices start from 1 end end A output :5x5 Array 2.0 3.0 4.0 5.0 6.0 3.0 4…

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## [How to get value of a Dict() after optimization in Julia 1.1.0](https://discourse.julialang.org/t/how-to-get-value-of-a-dict-after-optimization-in-julia-1-1-0/22617)

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**Author:** [@yan25y](https://discourse.julialang.org/u/yan25y)\
**Replies:** 4\
**Last updated:** [April 6, 2019, 3:30pm UTC](https://discourse.julialang.org/t/how-to-get-value-of-a-dict-after-optimization-in-julia-1-1-0/22617 "2019-04-06T15:30:28Z")

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I’m using JuMP to solve an optimization problem using Julia 1.1.0. I expressed my variable in dictionary form so I can see which variable gets picked. When I do the optimization on my Mac, I’m able to see the result usin…

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## [Plotting multiple points at every instance](https://discourse.julialang.org/t/plotting-multiple-points-at-every-instance/22814)

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**Author:** [@ennvvy](https://discourse.julialang.org/u/ennvvy)\
**Replies:** 6\
**Last updated:** [April 6, 2019, 2:30pm UTC](https://discourse.julialang.org/t/plotting-multiple-points-at-every-instance/22814 "2019-04-06T14:30:53Z")

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I am trying to plot the results of my Monte-Carlo simulation. I have data of the following form, where each row corresponds to a one-time instance. b1 500-element Array{Array{Float64,1},1}: \[115.0\] \[112.0, 113.…

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## [LU Factorizations in julia](https://discourse.julialang.org/t/lu-factorizations-in-julia/22819)

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**Author:** [@WILSON\_MASIH](https://discourse.julialang.org/u/WILSON_MASIH)\
**Replies:** 3\
**Last updated:** [April 6, 2019, 5:54am UTC](https://discourse.julialang.org/t/lu-factorizations-in-julia/22819 "2019-04-06T05:54:42Z")

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PA=LU Alu=lu(A) A\\b=Alu\\b det(A)=det(Alu)

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## [Simple linear regression question](https://discourse.julialang.org/t/simple-linear-regression-question/22749)

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**Author:** [@corwin](https://discourse.julialang.org/u/corwin)\
**Replies:** 3\
**Last updated:** [April 5, 2019, 8:56pm UTC](https://discourse.julialang.org/t/simple-linear-regression-question/22749 "2019-04-05T20:56:31Z")

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Hello! I apologize for possibly a simple question. I’m new to Julia, and maybe I didn’t find something in the description of StatsModels and TimeSeries. I have DataFrame data2 with time (yyyy-mm-dd) and 2 column with d…

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## [Empty remotechannel and resizing slurm jobs](https://discourse.julialang.org/t/empty-remotechannel-and-resizing-slurm-jobs/22816)

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**Author:** [@vancleve](https://discourse.julialang.org/u/vancleve)\
**Replies:** 0\
**Last updated:** [April 5, 2019, 8:41pm UTC](https://discourse.julialang.org/t/empty-remotechannel-and-resizing-slurm-jobs/22816 "2019-04-05T20:41:17Z")

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I am using RemoteChannels and Distributed for a multicore simulation with the template provided here: https://docs.julialang.org/en/v1/manual/parallel-computing/index.html#Channels-and-RemoteChannels-1 Each process can…

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## [Error using Plot in Julia](https://discourse.julialang.org/t/error-using-plot-in-julia/22809)

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**Author:** [@ennvvy](https://discourse.julialang.org/u/ennvvy)\
**Replies:** 5\
**Last updated:** [April 5, 2019, 8:24pm UTC](https://discourse.julialang.org/t/error-using-plot-in-julia/22809 "2019-04-05T20:24:10Z")

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I get an error every time I try plotting in Julia. The code I have been using to generate the histograms is as below: using StatsBase using Plots a = reshape(intl,(500\*100)) ; plt1 = fit(Histogram,a,30:10:150) ; plo…

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## [Constant objective function is not supported on JuMP 0.19?](https://discourse.julialang.org/t/constant-objective-function-is-not-supported-on-jump-0-19/22775)

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**Author:** [@SingingKim](https://discourse.julialang.org/u/SingingKim)\
**Replies:** 3\
**Last updated:** [April 5, 2019, 6:15pm UTC](https://discourse.julialang.org/t/constant-objective-function-is-not-supported-on-jump-0-19/22775 "2019-04-05T18:15:05Z")

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Good evening! I have set my objective function as a constant to check if the constraints set is feasible and JuMP returns an error. It seems like JuMP does not allow constant objective functions. Here is an example. u…

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## [Error JuMP in Julia version 0.7](https://discourse.julialang.org/t/error-jump-in-julia-version-0-7/22804)

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**Author:** [@angeloaliano1](https://discourse.julialang.org/u/angeloaliano1)\
**Replies:** 1\
**Last updated:** [April 5, 2019, 4:45pm UTC](https://discourse.julialang.org/t/error-jump-in-julia-version-0-7/22804 "2019-04-05T16:45:12Z")

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Hello Users, I don’t know that happened, but Julia don’t recognize the Package JuMP. When I run “using JuMP” the the errors appears: julia\> Pkg.add(“JuMP”) WARNING: Base.Pkg is deprecated, run using Pkg instead in …

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## [DifferentailEquations.jl error on multiple\_shooting\_objective](https://discourse.julialang.org/t/differentailequations-jl-error-on-multiple-shooting-objective/22387)

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**Author:** [@Andre\_Mello](https://discourse.julialang.org/u/Andre_Mello)\
**Replies:** 2\
**Last updated:** [April 5, 2019, 4:06pm UTC](https://discourse.julialang.org/t/differentailequations-jl-error-on-multiple-shooting-objective/22387 "2019-04-05T16:06:41Z")

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I’m still exploring the excellent DifferentialEquations.jl and came across this error today. I wanted to compare the different objective functions created by two\_stage\_method, build\_loss\_objective and multiple\_shooting\_…

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## [Julia vs R vs Python: simple MLE problem](https://discourse.julialang.org/t/julia-vs-r-vs-python-simple-mle-problem/9012)

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**Author:** [@xiaodai](https://discourse.julialang.org/u/xiaodai)\
**Replies:** 43\
**Last updated:** [April 5, 2019, 3:55pm UTC](https://discourse.julialang.org/t/julia-vs-r-vs-python-simple-mle-problem/9012 "2019-04-05T15:55:00Z")

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This is the draft of my new post (https://www.codementor.io/zhuojiadai/draft/gnqi4njro) on Julia vs R vs Python on a simple MLE problem. Unfortunately, Julia comes out slightly worse due to long compilation times. Welco…

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## [JuMP v0.19 & Ipopt: warm start (dual)](https://discourse.julialang.org/t/jump-v0-19-ipopt-warm-start-dual/22745)

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**Author:** [@pracherla9](https://discourse.julialang.org/u/pracherla9)\
**Replies:** 4\
**Last updated:** [April 5, 2019, 12:59pm UTC](https://discourse.julialang.org/t/jump-v0-19-ipopt-warm-start-dual/22745 "2019-04-05T12:59:20Z")

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Hi Miles: This is a follow-up to our discussion yesterday regarding a warm start of the dual using JuMP+Ipopt. Could you please point me to the relevant documentation on that? (Note that I’ve already taken full advantage…

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## [Mosek w/ multiple bound SecondOrderCones](https://discourse.julialang.org/t/mosek-w-multiple-bound-secondordercones/22777)

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**Author:** [@SingingKim](https://discourse.julialang.org/u/SingingKim)\
**Replies:** 3\
**Last updated:** [April 5, 2019, 10:23am UTC](https://discourse.julialang.org/t/mosek-w-multiple-bound-secondordercones/22777 "2019-04-05T10:23:24Z")

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Good evening! I have ‘multiple bound set’ issue regarding SecondOrderCone constraints with Mosek. (JuMP 0.19 / Mosek v8.1.0.80 ) using JuMP, Mosek, MosekTools, SCS m = Model(with\_optimizer(Mosek.Optimizer)) @variables…

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## [Reading (big) ascii files](https://discourse.julialang.org/t/reading-big-ascii-files/22697)

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**Author:** [@Paul18fr](https://discourse.julialang.org/u/Paul18fr)\
**Replies:** 11\
**Last updated:** [April 5, 2019, 8:12am UTC](https://discourse.julialang.org/t/reading-big-ascii-files/22697 "2019-04-05T08:12:27Z")

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Dear All After reading an article speaking about Julia, I decided to have a look on it both to deal with huge amount of data (through hdf5 files both in I/O) and to perform different type of calculations; nevertheless I…

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## [Solving a binary quadratic problem in CPLEX](https://discourse.julialang.org/t/solving-a-binary-quadratic-problem-in-cplex/22771)

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**Author:** [@angeloaliano1](https://discourse.julialang.org/u/angeloaliano1)\
**Replies:** 3\
**Last updated:** [April 5, 2019, 3:31am UTC](https://discourse.julialang.org/t/solving-a-binary-quadratic-problem-in-cplex/22771 "2019-04-05T03:31:34Z")

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Hello colleagues, I have the code: m = Model(with\_optimizer(CPLEX.Optimizer, CPX\_PARAM\_TILIM=1800,CPX\_PARAM\_SCRIND=0,CPX\_PARAM\_EPGAP=0.01)) @variables m begin x\[i in 1:5\] \>=3, Int end @objective(m,Min,sum(x\[i\]^2 fo…

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## [Request for comment: package for scientific and mathematical constants](https://discourse.julialang.org/t/request-for-comment-package-for-scientific-and-mathematical-constants/4155)

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**Author:** [@fasiha](https://discourse.julialang.org/u/fasiha)\
**Replies:** 31\
**Last updated:** [April 4, 2019, 10:16pm UTC](https://discourse.julialang.org/t/request-for-comment-package-for-scientific-and-mathematical-constants/4155 "2019-04-04T22:16:53Z")

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I’m refactoring some of our code and am wondering what to do with a few scientific constants we use, like speed of light, permittivity of free space, and the like. I was intrigued to see a stand-alone package, Tau.jl but…

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## [Setting the zcolor palette on a single plot (Plots.jl with pyplot)](https://discourse.julialang.org/t/setting-the-zcolor-palette-on-a-single-plot-plots-jl-with-pyplot/22713)

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**Author:** [@getzze](https://discourse.julialang.org/u/getzze)\
**Replies:** 2\
**Last updated:** [April 4, 2019, 1:44pm UTC](https://discourse.julialang.org/t/setting-the-zcolor-palette-on-a-single-plot-plots-jl-with-pyplot/22713 "2019-04-04T13:44:06Z")

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I am trying using pyplot backend with Plots.jl and to change the zcolor scheme (from the default :viridis to :balance for instance) for one particular figure. It is working with the gr backend but giving an error with py…

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## [How to save a heatmap as a png?](https://discourse.julialang.org/t/how-to-save-a-heatmap-as-a-png/22738)

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**Author:** [@HenrikM](https://discourse.julialang.org/u/HenrikM)\
**Replies:** 5\
**Last updated:** [April 4, 2019, 11:54am UTC](https://discourse.julialang.org/t/how-to-save-a-heatmap-as-a-png/22738 "2019-04-04T11:54:34Z")

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I can plot a matrix as a heatmap and I can even choose my own colormap. But how can I save just the heatmap (not the plot) as a png-file? For example: using Plots gr() xs = range(-1, 1, length=30) ys = range(-1, 1, len…

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## [Using RCall](https://discourse.julialang.org/t/using-rcall/22714)

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**Author:** [@Gunter\_Faes](https://discourse.julialang.org/u/Gunter_Faes)\
**Replies:** 7\
**Last updated:** [April 4, 2019, 11:37am UTC](https://discourse.julialang.org/t/using-rcall/22714 "2019-04-04T11:37:58Z")

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Hello, I’m still trying to solve my PCA problem, so I’m trying to use R over RCall. The package can be installed, but after using RCall, R reports up, but gets stuck! That is, nothing happens more…! The behavior applies…

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## [\`back!\` was already used error in Flux](https://discourse.julialang.org/t/back-was-already-used-error-in-flux/22709)

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**Author:** [@Dipak\_Narayan](https://discourse.julialang.org/u/Dipak_Narayan)\
**Replies:** 0\
**Last updated:** [April 3, 2019, 5:45pm UTC](https://discourse.julialang.org/t/back-was-already-used-error-in-flux/22709 "2019-04-03T17:45:18Z")

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What I’m trying to do is pass a linear combination of images (lets say a1img1 + a2img2 + a3\*img3) through a neural network and I want the network to choose the best a1, a2, a3 for classification. To do this I’ve made a …

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## [State of GIS package ecosystem?](https://discourse.julialang.org/t/state-of-gis-package-ecosystem/21864)

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**Author:** [@nickeubank](https://discourse.julialang.org/u/nickeubank)\
**Replies:** 11\
**Last updated:** [April 3, 2019, 11:39am UTC](https://discourse.julialang.org/t/state-of-gis-package-ecosystem/21864 "2019-04-03T11:39:17Z")

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I’m looking to move as much of my workflow as I can into julia from R/Python, and was hoping to get a sense of what the Julia GIS ecosystem looks like (especially for vector data). Has Julia developed anything like sp i…

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## [Help with hyper-stiff ODE system](https://discourse.julialang.org/t/help-with-hyper-stiff-ode-system/22681)

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**Author:** [@jcook](https://discourse.julialang.org/u/jcook)\
**Replies:** 2\
**Last updated:** [April 3, 2019, 10:22am UTC](https://discourse.julialang.org/t/help-with-hyper-stiff-ode-system/22681 "2019-04-03T10:22:19Z")

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Dear All, I’ve come against a pretty tricky problem that I can’t find an accurate and performant solution to in Julia. There is a closed source FORTRAN code that can solve this problem quickly and accurately. So at leas…

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## [PCA not working](https://discourse.julialang.org/t/pca-not-working/22645)

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**Author:** [@Gunter\_Faes](https://discourse.julialang.org/u/Gunter_Faes)\
**Replies:** 13\
**Last updated:** [April 3, 2019, 8:38am UTC](https://discourse.julialang.org/t/pca-not-working/22645 "2019-04-03T08:38:34Z")

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Hello, I’m working on the PCA from the MultivariateStats package and get the following error message (I’m working with ATOM): julia\> PCA\_Modell = fit(PCA, PCA\_Daten) ERROR: MethodError: no method matching fit(::Type{PC…

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