# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=372

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**Page:** 373

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## [Providing Objective, Gradient and Hessian to the Ipopt wrapper using a single function?](https://discourse.julialang.org/t/providing-objective-gradient-and-hessian-to-the-ipopt-wrapper-using-a-single-function/59675)

<div class="topic-metadata">

**Author:** [@dadada\_dadada](https://discourse.julialang.org/u/dadada_dadada)\
**Replies:** 12\
**Last updated:** [April 22, 2021, 1:30pm UTC](https://discourse.julialang.org/t/providing-objective-gradient-and-hessian-to-the-ipopt-wrapper-using-a-single-function/59675 "2021-04-22T13:30:23Z")

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Hello, I want to provide analytic expressions for the objective function, the gradient and the Hessian of the problem using a single function instead of three different functions. I am using Ipopt via the C wrapper in h…

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## [Annotation to figure with 2 Subplots](https://discourse.julialang.org/t/annotation-to-figure-with-2-subplots/59734)

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**Author:** [@hardy](https://discourse.julialang.org/u/hardy)\
**Replies:** 3\
**Last updated:** [April 22, 2021, 1:18pm UTC](https://discourse.julialang.org/t/annotation-to-figure-with-2-subplots/59734 "2021-04-22T13:18:20Z")

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Hello, I try to make a Plot with 2 Subplots and use the gr() backend. The first (p1) is a 3D surface plot and the 2. (p2) a 2D contour plot. The axis of both subplots are also different. I tried to put the annotation in…

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## [Nested vector variables in ODE problem definitions](https://discourse.julialang.org/t/nested-vector-variables-in-ode-problem-definitions/33417)

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**Author:** [@jonniedie](https://discourse.julialang.org/u/jonniedie)\
**Replies:** 6\
**Last updated:** [April 22, 2021, 1:05pm UTC](https://discourse.julialang.org/t/nested-vector-variables-in-ode-problem-definitions/33417 "2021-04-22T13:05:32Z")

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I am trying to define an ODE in which the state variables are nested in arrays. Here is a toy example: using DifferentialEquations function f!(du, u, p, t) du\[1\] = u\[1\] - u\[2\]\[1\] du\[2\] .= -5 \* u\[2\] return n…

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## [An example of Apache Arrow file?](https://discourse.julialang.org/t/an-example-of-apache-arrow-file/58299)

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**Author:** [@Sami](https://discourse.julialang.org/u/Sami)\
**Replies:** 7\
**Last updated:** [April 22, 2021, 11:56am UTC](https://discourse.julialang.org/t/an-example-of-apache-arrow-file/58299 "2021-04-22T11:56:53Z")

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Hello, I would like to test Julia’s support for Apache Arrow with a big file that doesn’t fit to memory (RAM). I can’t find any example of such file, could you help me with this please? I guess I need a file that is in…

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## [Importing CairoMakie prevents sampling](https://discourse.julialang.org/t/importing-cairomakie-prevents-sampling/59501)

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**Author:** [@jzr](https://discourse.julialang.org/u/jzr)\
**Replies:** 7\
**Last updated:** [April 22, 2021, 8:47am UTC](https://discourse.julialang.org/t/importing-cairomakie-prevents-sampling/59501 "2021-04-22T08:47:42Z")

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I have a script that runs fine unless I have import CairoMakie at the top. Then it hangs. How can I diagnose this? It hangs at mcmc\_with\_warmup. The same thing happens whether I have using CairoMakie or import CairoMaki…

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## [Colour plot points based on another vector](https://discourse.julialang.org/t/colour-plot-points-based-on-another-vector/59776)

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**Author:** [@SDA](https://discourse.julialang.org/u/SDA)\
**Replies:** 3\
**Last updated:** [April 22, 2021, 7:56am UTC](https://discourse.julialang.org/t/colour-plot-points-based-on-another-vector/59776 "2021-04-22T07:56:57Z")

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Hi everyone, I am trying to amend the example given here: https://discourse.julialang.org/t/plot-a-vector-of-arrays/54956, which plots a vector of arrays. The example I am working with is a 3D plot but hopefully the 2D…

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## [DiffEqFlux.sciml\_train fails with save\_idxs keyword](https://discourse.julialang.org/t/diffeqflux-sciml-train-fails-with-save-idxs-keyword/56864)

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**Author:** [@moesphere](https://discourse.julialang.org/u/moesphere)\
**Replies:** 3\
**Last updated:** [April 22, 2021, 7:39am UTC](https://discourse.julialang.org/t/diffeqflux-sciml-train-fails-with-save-idxs-keyword/56864 "2021-04-22T07:39:05Z")

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Training via DiffEqFlux fails when save\_idxs keyword is used within the loss function. Differentiation seems to be the problem. Evaluation of the loss function works fine. MWE is taken from the docs using DifferentialE…

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## [Time-period-based time series moving windows in Julia?](https://discourse.julialang.org/t/time-period-based-time-series-moving-windows-in-julia/59745)

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**Author:** [@luke](https://discourse.julialang.org/u/luke)\
**Replies:** 5\
**Last updated:** [April 22, 2021, 7:21am UTC](https://discourse.julialang.org/t/time-period-based-time-series-moving-windows-in-julia/59745 "2021-04-22T07:21:06Z")

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Looking at windowing in TimeSeries.jl, which seems to be the main package for time series data in Julia, I can’t find anything equivalent to the native time-period-based windowing offered in Pandas, which supports window…

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## [How to avoid repeating code between back-, middle-, and front-ends?](https://discourse.julialang.org/t/how-to-avoid-repeating-code-between-back-middle-and-front-ends/59697)

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**Author:** [@yakir12](https://discourse.julialang.org/u/yakir12)\
**Replies:** 5\
**Last updated:** [April 22, 2021, 7:17am UTC](https://discourse.julialang.org/t/how-to-avoid-repeating-code-between-back-middle-and-front-ends/59697 "2021-04-22T07:17:42Z")

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When building a full-stack app, I find it frustrating to define basically 3 nearly identical types: What I consider the main struct: defining the logic of the type disregarding any GUI/DB needs. This is the struct you’…

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## [Changing line weight and font in PlotlyJS](https://discourse.julialang.org/t/changing-line-weight-and-font-in-plotlyjs/59677)

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**Author:** [@mkarikom](https://discourse.julialang.org/u/mkarikom)\
**Replies:** 7\
**Last updated:** [April 22, 2021, 7:16am UTC](https://discourse.julialang.org/t/changing-line-weight-and-font-in-plotlyjs/59677 "2021-04-22T07:16:40Z")

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Thanks for reading and please see below for a MWE parcoords() with the Plotly backend. This MWE generates no errors. background I just need a parallel coordinates plot. In general, I prefer the gr() or pyplot() backen…

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## [Periodic boundary conditions for PDE system using ModellingToolkit and DiffEqBase](https://discourse.julialang.org/t/periodic-boundary-conditions-for-pde-system-using-modellingtoolkit-and-diffeqbase/51827)

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**Author:** [@archermarx](https://discourse.julialang.org/u/archermarx)\
**Replies:** 6\
**Last updated:** [April 22, 2021, 5:56am UTC](https://discourse.julialang.org/t/periodic-boundary-conditions-for-pde-system-using-modellingtoolkit-and-diffeqbase/51827 "2021-04-22T05:56:28Z")

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I’m working with ModellingToolkit and DiffEqOperators to solve a set of PDEs, and I wanted to test out a simpler problem before I jumped into a more complicated problem. I followed the heat equation example and that work…

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## [Using symmetry with TensorKit: ERROR: LoadError: MethodError: no method matching similarstructure\_from\_indices](https://discourse.julialang.org/t/using-symmetry-with-tensorkit-error-loaderror-methoderror-no-method-matching-similarstructure-from-indices/59572)

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**Author:** [@Nellatur](https://discourse.julialang.org/u/Nellatur)\
**Replies:** 1\
**Last updated:** [April 22, 2021, 2:53am UTC](https://discourse.julialang.org/t/using-symmetry-with-tensorkit-error-loaderror-methoderror-no-method-matching-similarstructure-from-indices/59572 "2021-04-22T02:53:58Z")

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I tried to utilize symmetry in tensor contraction A\[a,b\]\*B\[b,c,d\] = C\[a,c,d\] with B\[b,c,d\] = B\[b,d,c\]. Based on Tutorial · TensorKit.jl I tried the following code using TensorKit using BenchmarkTools #using Tensor…

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## [Pros and cons of using Flux directly over using MLJ/MLJFlux](https://discourse.julialang.org/t/pros-and-cons-of-using-flux-directly-over-using-mlj-mljflux/59756)

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**Author:** [@ablaom](https://discourse.julialang.org/u/ablaom)\
**Replies:** 2\
**Last updated:** [April 22, 2021, 12:07am UTC](https://discourse.julialang.org/t/pros-and-cons-of-using-flux-directly-over-using-mlj-mljflux/59756 "2021-04-22T00:07:28Z")

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The following question has been posted on slack: “Can anyone guide me on the relative merits of using MLJ with MLJFlux vs. using Flux directly?”

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## [Writing a dataframe to Excel XLSX](https://discourse.julialang.org/t/writing-a-dataframe-to-excel-xlsx/59748)

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**Author:** [@Smith](https://discourse.julialang.org/u/Smith)\
**Replies:** 5\
**Last updated:** [April 21, 2021, 9:32pm UTC](https://discourse.julialang.org/t/writing-a-dataframe-to-excel-xlsx/59748 "2021-04-21T21:32:35Z")

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Can we write a dataframe (without headers) to a specified sheet and specified cell in Excel? I have a dataframe that I want to write to a specific sheet in a spreadsheet. Consider this dataframe df = DataFrame(Name=\["aa…

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## [Derivative with Zygote/ForwardDiff of a function of multiple vectors wrt a subset of arguments](https://discourse.julialang.org/t/derivative-with-zygote-forwarddiff-of-a-function-of-multiple-vectors-wrt-a-subset-of-arguments/59560)

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**Author:** [@Albert\_Zevelev](https://discourse.julialang.org/u/Albert_Zevelev)\
**Replies:** 1\
**Last updated:** [April 21, 2021, 7:48pm UTC](https://discourse.julialang.org/t/derivative-with-zygote-forwarddiff-of-a-function-of-multiple-vectors-wrt-a-subset-of-arguments/59560 "2021-04-21T19:48:53Z")

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I can differentiate a function of one vector, but not multiple vectors using ForwardDiff, Zygote f(x) = 3.0\*x\[1\] + 5.0\*x\[2\]^2.0 fpF(x) = ForwardDiff.gradient(f,x) fpZ(x) = Zygote.forward\_jacobian(f,x)\[2\] # xx = 2.0\*o…

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## [ReverseDiff over Zygote to differentiate neural network using GalacticOptim - Dimension mismatch](https://discourse.julialang.org/t/reversediff-over-zygote-to-differentiate-neural-network-using-galacticoptim-dimension-mismatch/59744)

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**Author:** [@RynoLaubscher](https://discourse.julialang.org/u/RynoLaubscher)\
**Replies:** 2\
**Last updated:** [April 21, 2021, 7:21pm UTC](https://discourse.julialang.org/t/reversediff-over-zygote-to-differentiate-neural-network-using-galacticoptim-dimension-mismatch/59744 "2021-04-21T19:21:16Z")

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Hi All, I am struggling a bit with using GalacticOptim.AutoReverseDiff to find the gradients over a loss function which internally calculates a gradient using Zygote. Running ForwardDiff over the function works fine but …

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## [How to put numbers on top of each bar in a bar chart?](https://discourse.julialang.org/t/how-to-put-numbers-on-top-of-each-bar-in-a-bar-chart/59743)

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**Author:** [@zxjroger](https://discourse.julialang.org/u/zxjroger)\
**Replies:** 4\
**Last updated:** [April 21, 2021, 5:07pm UTC](https://discourse.julialang.org/t/how-to-put-numbers-on-top-of-each-bar-in-a-bar-chart/59743 "2021-04-21T17:07:35Z")

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I tried to make a chart like this, but I couldn’t find a way to show the numbers on top of each bar.

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## [AGP with linear predictors](https://discourse.julialang.org/t/agp-with-linear-predictors/59630)

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**Author:** [@jzr](https://discourse.julialang.org/u/jzr)\
**Replies:** 3\
**Last updated:** [April 21, 2021, 4:50pm UTC](https://discourse.julialang.org/t/agp-with-linear-predictors/59630 "2021-04-21T16:50:14Z")

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Continuing my experiments from another thread using the suggestion of @theogf, I have some code using AGP. With a single predictor I can fit: using AugmentedGaussianProcesses const AGP = AugmentedGaussianProcesses using…

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## [Print DataFrame as "less"-command style](https://discourse.julialang.org/t/print-dataframe-as-less-command-style/40667)

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**Author:** [@carlomontec](https://discourse.julialang.org/u/carlomontec)\
**Replies:** 4\
**Last updated:** [April 21, 2021, 4:01pm UTC](https://discourse.julialang.org/t/print-dataframe-as-less-command-style/40667 "2021-04-21T16:01:07Z")

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Hello, is there a way to print to screen a DataFrame in similar fashion as the “less” command in Linux? So that it displays the data that fits the current terminal size, and with the arrow keys to scroll the columns and…

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## [3D convolution, de-convolution layers in Flux for training 3D MRI data](https://discourse.julialang.org/t/3d-convolution-de-convolution-layers-in-flux-for-training-3d-mri-data/11917)

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**Author:** [@Azamat](https://discourse.julialang.org/u/Azamat)\
**Replies:** 4\
**Last updated:** [April 21, 2021, 3:54pm UTC](https://discourse.julialang.org/t/3d-convolution-de-convolution-layers-in-flux-for-training-3d-mri-data/11917 "2021-04-21T15:54:55Z")

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Are there 3D convolution, de-convolution layers in Flux.jl? Or is there any implementation that can be used with Flux.jl? To elaborate I have 3D greyscale images (MRI scans), i.e. each voxel value is a number. Now is t…

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## [Solving a constraint lasso](https://discourse.julialang.org/t/solving-a-constraint-lasso/59727)

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**Author:** [@lrnv](https://discourse.julialang.org/u/lrnv)\
**Replies:** 2\
**Last updated:** [April 21, 2021, 3:33pm UTC](https://discourse.julialang.org/t/solving-a-constraint-lasso/59727 "2021-04-21T15:33:25Z")

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Hi, Recently i had the problem of solving a constraint lasso, much like the one described in this paper. The paper refers to a julia package, ConstrainedLasso.jl, that is unfornutely not updated since julia 0.6. With so…

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## [DataFrames unique - keep last occurence](https://discourse.julialang.org/t/dataframes-unique-keep-last-occurence/59723)

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**Author:** [@Iulian.Cioarca](https://discourse.julialang.org/u/Iulian.Cioarca)\
**Replies:** 6\
**Last updated:** [April 21, 2021, 2:33pm UTC](https://discourse.julialang.org/t/dataframes-unique-keep-last-occurence/59723 "2021-04-21T14:33:40Z")

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I have the following dataframe, where :a and :b are some conditions and :c is an output: df = DataFrame(a=\[1,1,2,2,1\], b=\[1,2,1,2,1\],c=randn(5)) As you can see, the last row has the same conditions as first row (a=1, …

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## [OrdinaryDiffEq: unexpected results in DEDataArray](https://discourse.julialang.org/t/ordinarydiffeq-unexpected-results-in-dedataarray/59282)

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**Author:** [@AlexS12](https://discourse.julialang.org/u/AlexS12)\
**Replies:** 10\
**Last updated:** [April 21, 2021, 2:29pm UTC](https://discourse.julialang.org/t/ordinarydiffeq-unexpected-results-in-dedataarray/59282 "2021-04-21T14:29:26Z")

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I am trying to solve a ODE using a DEDataVector to pass and store parameters that come from evaluating functions taking the state vector as argument. After reading the documentation I expected to obtain the value of the …

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## [White noise for 'SDEs with diagonal noise'](https://discourse.julialang.org/t/white-noise-for-sdes-with-diagonal-noise/59695)

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**Author:** [@Frederic\_Gilt](https://discourse.julialang.org/u/Frederic_Gilt)\
**Replies:** 10\
**Last updated:** [April 21, 2021, 12:55pm UTC](https://discourse.julialang.org/t/white-noise-for-sdes-with-diagonal-noise/59695 "2021-04-21T12:55:02Z")

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dear all, I have a SDEs with a stochastic part as a white noise k\*N(0,1). Time step is ‘dt’ Following explanations here I don’t get why the white noise is N(0,dt) and not N(0,1/dt), which seems consitent with my resul…

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## [Flux: implementing efficient RBF layer](https://discourse.julialang.org/t/flux-implementing-efficient-rbf-layer/59402)

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**Author:** [@Rasmus\_Hoier](https://discourse.julialang.org/u/Rasmus_Hoier)\
**Replies:** 5\
**Last updated:** [April 21, 2021, 12:15pm UTC](https://discourse.julialang.org/t/flux-implementing-efficient-rbf-layer/59402 "2021-04-21T12:15:48Z")

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Hi, I am new to Flux and could use some feedback on how to optimize some code. Using the source code for the Dense layer as a reference I made a radial basis function (RBF) layer. I am able to train networks using the …

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## [PresetTimeCallback does not reach u\[1\] if save\_positions = false & using interpolations](https://discourse.julialang.org/t/presettimecallback-does-not-reach-u-1-if-save-positions-false-using-interpolations/59719)

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**Author:** [@Janssena](https://discourse.julialang.org/u/Janssena)\
**Replies:** 4\
**Last updated:** [April 21, 2021, 10:22am UTC](https://discourse.julialang.org/t/presettimecallback-does-not-reach-u-1-if-save-positions-false-using-interpolations/59719 "2021-04-21T10:22:18Z")

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Hey All, I’m trying to calculate the error of a differential equations sol object with respect to specific timepoints. The system is made up as follows: function dAdt(dA, A, p, t) CL, V1, Q, V2 = p k₁₀ = CL / …

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## [Adding a SOS2 constraint for a variable which is defined over a DenseAxisArray?](https://discourse.julialang.org/t/adding-a-sos2-constraint-for-a-variable-which-is-defined-over-a-denseaxisarray/59637)

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**Author:** [@Mastomaki](https://discourse.julialang.org/u/Mastomaki)\
**Replies:** 2\
**Last updated:** [April 21, 2021, 8:21am UTC](https://discourse.julialang.org/t/adding-a-sos2-constraint-for-a-variable-which-is-defined-over-a-denseaxisarray/59637 "2021-04-21T08:21:48Z")

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Hello! I wonder how to add a SOS2 constraint with JuMP for a variable which is defined over a DenseAxisArray or SparseAxisArray? For example: using JuMP mymod = Model(); #sets node = \["n1", "n2", "n3"\] #declare var…

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## [Adding variables with the Clp solver in MathOptInterface](https://discourse.julialang.org/t/adding-variables-with-the-clp-solver-in-mathoptinterface/59540)

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**Author:** [@leejm516](https://discourse.julialang.org/u/leejm516)\
**Replies:** 4\
**Last updated:** [April 21, 2021, 5:55am UTC](https://discourse.julialang.org/t/adding-variables-with-the-clp-solver-in-mathoptinterface/59540 "2021-04-21T05:55:11Z")

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Hi, I am trying to be familiar with MathOptInterface, in order to revise a package that has been written with MathProgBase. When I tried to add a variable into the Clp model, I got the following error. julia\> using M…

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## [Solve a routine economics PDE from an HJB w/ ModelingToolkit](https://discourse.julialang.org/t/solve-a-routine-economics-pde-from-an-hjb-w-modelingtoolkit/49718)

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**Author:** [@Albert\_Zevelev](https://discourse.julialang.org/u/Albert_Zevelev)\
**Replies:** 33\
**Last updated:** [April 21, 2021, 5:29am UTC](https://discourse.julialang.org/t/solve-a-routine-economics-pde-from-an-hjb-w-modelingtoolkit/49718 "2021-04-21T05:29:10Z")

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Consider a routine continuous time optimization problem from economics: V(t,a\_{t}) := \\max \\int\_{\\tau=t}^{\\tau = T} e^{-\\rho (\\tau -t)} u(c\_{\\tau})d\\tau \\text{ s.t. } \\dot{a}\_{t} = y + ra\_{t} - c\_{t}, a\_{0} \\text…

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## [The problem of calling “MKL pardiso” in Julia](https://discourse.julialang.org/t/the-problem-of-calling-mkl-pardiso-in-julia/25830)

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**Author:** [@FujiwaraTakumiEH](https://discourse.julialang.org/u/FujiwaraTakumiEH)\
**Replies:** 6\
**Last updated:** [April 21, 2021, 4:19am UTC](https://discourse.julialang.org/t/the-problem-of-calling-mkl-pardiso-in-julia/25830 "2021-04-21T04:19:01Z")

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Background： I have a large sparse matrix written by Julia that requires solutions, and I want to use MKL pardiso to improve speed. I’ve found the pardiso.jl page and read README. What I’ve done： Install Pardiso in Jul…

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