# \#ordinarydiffeq

**URL:** https://discourse.julialang.org/tag/ordinarydiffeq/837.md

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## [\[ANN\] SymbolicAWEModels.jl — a compiler for mechanical systems, built for Airborne Wind Energy](https://discourse.julialang.org/t/ann-symbolicawemodels-jl-a-compiler-for-mechanical-systems-built-for-airborne-wind-energy/137473)

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**Author:** [@Bart\_van\_de\_Lint](https://discourse.julialang.org/u/Bart_van_de_Lint)\
**Replies:** 2\
**Last updated:** [June 7, 2026, 8:17am UTC](https://discourse.julialang.org/t/ann-symbolicawemodels-jl-a-compiler-for-mechanical-systems-built-for-airborne-wind-energy/137473 "2026-06-07T08:17:42Z")

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Hi all, I’m happy to announce SymbolicAWEModels.jl (registered, currently v0.11.1). It’s best thought of as a compiler for flexible mechanical systems. You describe a structure — point masses, spring-damper segments…

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## [Strange error when using the FBDF solver](https://discourse.julialang.org/t/strange-error-when-using-the-fbdf-solver/136405)

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**Author:** [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Replies:** 1\
**Last updated:** [March 27, 2026, 12:58pm UTC](https://discourse.julialang.org/t/strange-error-when-using-the-fbdf-solver/136405 "2026-03-27T12:58:54Z")

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When I run the following script Tethers.jl/src/Tether\_06c.jl at main · ufechner7/Tethers.jl · GitHub on Windows with continues callbacks using the FBDF solver I get the following error: 4 ┌ Warning: \`ODESystem(args...; …

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## [Best practices for testing numerical results that are unstable across package versions](https://discourse.julialang.org/t/best-practices-for-testing-numerical-results-that-are-unstable-across-package-versions/135847)

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**Author:** [@jakobjpeters](https://discourse.julialang.org/u/jakobjpeters)\
**Replies:** 30\
**Last updated:** [March 2, 2026, 12:37pm UTC](https://discourse.julialang.org/t/best-practices-for-testing-numerical-results-that-are-unstable-across-package-versions/135847 "2026-03-02T12:37:47Z")

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My team is using OrdinaryDiffEq.jl and several other numerical packages, where we are testing a variety of solver results to be within some tolerance. On multiple occasions, some of these tests have begun to fail after u…

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## [Where to report a bug in OrdinaryDiffEqBDF](https://discourse.julialang.org/t/where-to-report-a-bug-in-ordinarydiffeqbdf/135759)

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**Author:** [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Replies:** 4\
**Last updated:** [February 21, 2026, 4:48am UTC](https://discourse.julialang.org/t/where-to-report-a-bug-in-ordinarydiffeqbdf/135759 "2026-02-21T04:48:56Z")

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KiteModels.jl precompiles successfully now with max\_order: 5, but not with max\_order: 4. This is just a workaround for the bug in OrdinaryDiffEqBDF v1.17.0. You should still report the Val(5) hardcoding bug upstream so m…

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## [Stokes solver as an ODEproblem takes time to initiate](https://discourse.julialang.org/t/stokes-solver-as-an-odeproblem-takes-time-to-initiate/135317)

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**Author:** [@Iddingsite](https://discourse.julialang.org/u/Iddingsite)\
**Replies:** 6\
**Last updated:** [January 29, 2026, 10:15am UTC](https://discourse.julialang.org/t/stokes-solver-as-an-odeproblem-takes-time-to-initiate/135317 "2026-01-29T10:15:42Z")

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Hi everyone. I wrote a small code to solve 2D linear visco-elastic Stokes using finite difference and OrdinaryDiffEq to test how that would work out. So, in this case, I only have algebraic equations and have some param…

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## [Singular BVP with integrable boundaries](https://discourse.julialang.org/t/singular-bvp-with-integrable-boundaries/135224)

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**Author:** [@NoFishLikeIan](https://discourse.julialang.org/u/NoFishLikeIan)\
**Replies:** 2\
**Last updated:** [January 26, 2026, 7:13am UTC](https://discourse.julialang.org/t/singular-bvp-with-integrable-boundaries/135224 "2026-01-26T07:13:46Z")

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I’m solving a singular first-order, two dimensional ODE arising in reputation games (Faingold & Sannikov, 2011). On \\phi \\in \[0, 1\], I have u' = \\frac{v}{\\phi(1-\\phi)} \\\\ v' = \\frac{1}{\\phi(1-\\phi)} \\left(v + 2\\rho \\f…

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## [OrdinaryDiffEq with a mass\_matrix and jac\_prototype](https://discourse.julialang.org/t/ordinarydiffeq-with-a-mass-matrix-and-jac-prototype/134462)

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**Author:** [@bmxam](https://discourse.julialang.org/u/bmxam)\
**Replies:** 4\
**Last updated:** [December 10, 2025, 5:13pm UTC](https://discourse.julialang.org/t/ordinarydiffeq-with-a-mass-matrix-and-jac-prototype/134462 "2025-12-10T17:13:08Z")

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Hi everyone, Short story : see the MWE below. Using OrdinaryDiffEq, I’m trying to solve an ODE involving a mass\_matrix that (may) evolve depending on the solution, the time, the parameters. So I set up a SciMLOperators…

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## [MTK - solve: weird error message](https://discourse.julialang.org/t/mtk-solve-weird-error-message/131638)

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**Author:** [@BLI](https://discourse.julialang.org/u/BLI)\
**Replies:** 7\
**Last updated:** [August 24, 2025, 7:28am UTC](https://discourse.julialang.org/t/mtk-solve-weird-error-message/131638 "2025-08-24T07:28:05Z")

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I’m on Julia v1.11.6 on Windows 11 64bit, using MTK v10.19.0, OrdinaryDiffEq v6.101.0. I try to use Clapeyron v0.6.15 with the code. My code worked without a flaw (except some warnings related to arrays and Clapeyron) i…

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## [Unhelpful interpolation for solution from differential equation](https://discourse.julialang.org/t/unhelpful-interpolation-for-solution-from-differential-equation/130857)

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**Author:** [@miles-1](https://discourse.julialang.org/u/miles-1)\
**Replies:** 3\
**Last updated:** [July 20, 2025, 1:40am UTC](https://discourse.julialang.org/t/unhelpful-interpolation-for-solution-from-differential-equation/130857 "2025-07-20T01:40:23Z")

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I am trying to use the solution from my differential equation to find local maxima. I am following the example found here, but am running into an issue. I have found that the interpolation of my solution is very poor. He…

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## [Combining \`SparseDiffTools.jl\` and \`OrdinaryDiffEq.jl\`](https://discourse.julialang.org/t/combining-sparsedifftools-jl-and-ordinarydiffeq-jl/130555)

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**Author:** [@DanDoe](https://discourse.julialang.org/u/DanDoe)\
**Replies:** 8\
**Last updated:** [July 9, 2025, 10:53am UTC](https://discourse.julialang.org/t/combining-sparsedifftools-jl-and-ordinarydiffeq-jl/130555 "2025-07-09T10:53:43Z")

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I managed to get the sparsity structure detection (via SparseDiffTools.j) of the rhs! function (the RHS of the ODE problem fed into OrdinaryDiffEq.jl) for our code Trixi.jl to run. Can I supply the cache = sparse\_jacob…

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## [How to reinit! an integrator in a non-allocating and consistent way?](https://discourse.julialang.org/t/how-to-reinit-an-integrator-in-a-non-allocating-and-consistent-way/127771)

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**Author:** [@Bart\_van\_de\_Lint](https://discourse.julialang.org/u/Bart_van_de_Lint)\
**Replies:** 10\
**Last updated:** [April 9, 2025, 6:37pm UTC](https://discourse.julialang.org/t/how-to-reinit-an-integrator-in-a-non-allocating-and-consistent-way/127771 "2025-04-09T18:37:47Z")

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I am trying to create a control function from a ModelingToolkit.jl model: f(x, u, p) → x\_next I want to do that by re-initializing the integrator with the current state x and input u, and then stepping the integrator: …

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## [Usage of OrdinaryDiffEqLinear.jl for non-autonomous problems](https://discourse.julialang.org/t/usage-of-ordinarydiffeqlinear-jl-for-non-autonomous-problems/127662)

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**Author:** [@ultimatile](https://discourse.julialang.org/u/ultimatile)\
**Replies:** 5\
**Last updated:** [April 5, 2025, 9:34pm UTC](https://discourse.julialang.org/t/usage-of-ordinarydiffeqlinear-jl-for-non-autonomous-problems/127662 "2025-04-05T21:34:16Z")

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I’m trying to use OrdinaryDiffEqLinear.jl 's the state-independent Magnus solvers to solve non-autonomous Linear ODEs. To confirm the usage, I’m trying to solve \\dot{\\boldsymbol{u}}(t)=\\begin{pmatrix}0&-\\alpha t\\\\\\alp…

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## [Automatic Differentiation of quantum master equation using Zygote](https://discourse.julialang.org/t/automatic-differentiation-of-quantum-master-equation-using-zygote/127715)

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**Author:** [@albertomercurio](https://discourse.julialang.org/u/albertomercurio)\
**Replies:** 14\
**Last updated:** [April 5, 2025, 7:14pm UTC](https://discourse.julialang.org/t/automatic-differentiation-of-quantum-master-equation-using-zygote/127715 "2025-04-05T19:14:43Z")

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Hello, I need to differentiate a quantum master equation over a parameter, using QuantumToolbox.jl. Under the hood it is simply an Ordinary Differential Equation involving SciMLOperators. I’m able to differentiate the …

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## [Save ODE solution for specific values of one state variable](https://discourse.julialang.org/t/save-ode-solution-for-specific-values-of-one-state-variable/126168)

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**Author:** [@afossa](https://discourse.julialang.org/u/afossa)\
**Replies:** 2\
**Last updated:** [March 27, 2025, 6:40pm UTC](https://discourse.julialang.org/t/save-ode-solution-for-specific-values-of-one-state-variable/126168 "2025-03-27T18:40:54Z")

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Hello, I am using DifferentialEquations.jl to solve a system of ordinary differential equations (an ODEProblem) of the form du = f(u, p, t) where u is a vector. One component of u, say u\[1\], is monotonically increasing…

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## [Making Enzyme.jl work with the integrator interface of OrdinaryDiffEq.jl](https://discourse.julialang.org/t/making-enzyme-jl-work-with-the-integrator-interface-of-ordinarydiffeq-jl/126186)

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**Author:** [@Rittick\_Roy](https://discourse.julialang.org/u/Rittick_Roy)\
**Replies:** 11\
**Last updated:** [February 25, 2025, 1:30pm UTC](https://discourse.julialang.org/t/making-enzyme-jl-work-with-the-integrator-interface-of-ordinarydiffeq-jl/126186 "2025-02-25T13:30:33Z")

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I’m new to using autodiff in Julia and have some issues making Enzyme.jl work with OrdinaryDiffEq.jl. I want to take the a reverse mode derivative of my differential equation solution with respect to the input parameter …

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## [ForwardDiff + Adaptive ODE Solvers: Timestep Issue Leads to Incorrect Derivatives](https://discourse.julialang.org/t/forwarddiff-adaptive-ode-solvers-timestep-issue-leads-to-incorrect-derivatives/125870)

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**Author:** [@abavoil](https://discourse.julialang.org/u/abavoil)\
**Replies:** 5\
**Last updated:** [February 14, 2025, 3:08pm UTC](https://discourse.julialang.org/t/forwarddiff-adaptive-ode-solvers-timestep-issue-leads-to-incorrect-derivatives/125870 "2025-02-14T15:08:36Z")

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Hello dear Julia community, TLDR; Passing dual numbers (ForwardDiff.jl) into an adaptative-step ODE solver (OrdinaryDiffEq.jl) affects the timestep choice, making the derivative incorrect. Let’s say we have a function …

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## [Makie recipe to plot ODESolution of DifferentialEquations.jl?](https://discourse.julialang.org/t/makie-recipe-to-plot-odesolution-of-differentialequations-jl/105879)

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**Author:** [@homocomputeris](https://discourse.julialang.org/u/homocomputeris)\
**Replies:** 11\
**Last updated:** [January 23, 2025, 12:28am UTC](https://discourse.julialang.org/t/makie-recipe-to-plot-odesolution-of-differentialequations-jl/105879 "2025-01-23T00:28:55Z")

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Related to this question. Is there a recipe to plot the DiffEq solution components against time? I tried Makie.convert\_arguments(sol::ODESolution) = (sol.t, \[\[v\[1\] for v in sol.u\], \[\[v\[2\] for v in sol.u\]\]\]) but it pl…

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## [Warning during tests](https://discourse.julialang.org/t/warning-during-tests/124796)

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**Author:** [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Replies:** 3\
**Last updated:** [January 15, 2025, 5:04pm UTC](https://discourse.julialang.org/t/warning-during-tests/124796 "2025-01-15T17:04:18Z")

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When I run the tests of KiteModels.jl I get the warning: ┌ Warning: Using a \`Bool\` for keyword argument \`autodiff\` is deprecated. Please use an \`ADType\` specifier. │ caller = \_process\_AD\_choice(ad\_alg::Bool, chunksize…

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## [Installing OrdinaryDiffEqBDF fails](https://discourse.julialang.org/t/installing-ordinarydiffeqbdf-fails/122767)

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**Author:** [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Replies:** 6\
**Last updated:** [November 18, 2024, 2:10pm UTC](https://discourse.julialang.org/t/installing-ordinarydiffeqbdf-fails/122767 "2024-11-18T14:10:42Z")

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If I try to install OrdinaryDiffEqBDF in a new, empty project I get the following error: ufechner@framework:~/repos/Ord$ julia --project="." \_ \_ \_ \_(\_)\_ | Documentation: https://docs.juliala…

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## [Using OrdinaryDiffEQ Integrator interface for split step](https://discourse.julialang.org/t/using-ordinarydiffeq-integrator-interface-for-split-step/122313)

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**Author:** [@erny123](https://discourse.julialang.org/u/erny123)\
**Replies:** 12\
**Last updated:** [November 7, 2024, 11:06pm UTC](https://discourse.julialang.org/t/using-ordinarydiffeq-integrator-interface-for-split-step/122313 "2024-11-07T23:06:20Z")

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hi all, Looking to see if someone can help me out. Currently working with Trixi.jl and it’s great. However, because it’s fairly new, there are some things that have not been implemented. For example, handling nonlinear…

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## [Installing OrdinaryEqDiff on Julia 1.10](https://discourse.julialang.org/t/installing-ordinaryeqdiff-on-julia-1-10/121780)

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**Author:** [@nicomerino](https://discourse.julialang.org/u/nicomerino)\
**Replies:** 6\
**Last updated:** [October 26, 2024, 6:19pm UTC](https://discourse.julialang.org/t/installing-ordinaryeqdiff-on-julia-1-10/121780 "2024-10-26T18:19:40Z")

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Hey there, I having trouble installing OrdinaryEqDiff and I have no clue what the problem could be. It just gets stuck forever, always in this specific part: Info Packages marked with ⌅ have new versions availa…

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## [Magnus solver slow compared with Tsitouras for linear state independent ODE](https://discourse.julialang.org/t/magnus-solver-slow-compared-with-tsitouras-for-linear-state-independent-ode/121118)

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**Author:** [@facusapienza](https://discourse.julialang.org/u/facusapienza)\
**Replies:** 5\
**Last updated:** [October 10, 2024, 10:49pm UTC](https://discourse.julialang.org/t/magnus-solver-slow-compared-with-tsitouras-for-linear-state-independent-ode/121118 "2024-10-10T22:49:44Z")

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Hi! I was playing a bit with the Magnus solvers included in the examples for linear ODEs in the docs: Non-autonomous Linear ODE / Lie Group ODE Solvers. I was particularly interesting in benchmarking the solver I am cur…

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## [Parameter estimation in biological network](https://discourse.julialang.org/t/parameter-estimation-in-biological-network/119630)

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**Author:** [@Nick1](https://discourse.julialang.org/u/Nick1)\
**Replies:** 7\
**Last updated:** [September 20, 2024, 6:55am UTC](https://discourse.julialang.org/t/parameter-estimation-in-biological-network/119630 "2024-09-20T06:55:37Z")

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I am working on a large signaling pathway and trying to get a rough estimation of the baseline parameters. I have been trying to do the fitting with the Particle Swarm Optimization from Metaheuristics.jl but it does not …

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## [Time integration in OrdinaryDiffEq.jl in Julia is slower than calling it from Python](https://discourse.julialang.org/t/time-integration-in-ordinarydiffeq-jl-in-julia-is-slower-than-calling-it-from-python/119123)

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**Author:** [@dmitry-kabanov](https://discourse.julialang.org/u/dmitry-kabanov)\
**Replies:** 12\
**Last updated:** [September 16, 2024, 7:17pm UTC](https://discourse.julialang.org/t/time-integration-in-ordinarydiffeq-jl-in-julia-is-slower-than-calling-it-from-python/119123 "2024-09-16T19:17:43Z")

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Hi, I work on the software that allows to call numerical solvers across different languages, which is implemented using libffi (Function Foreign Interface library). I was working recently on the performance study, to s…

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## [Writing parallel worker output to .out file in slurm to track progress](https://discourse.julialang.org/t/writing-parallel-worker-output-to-out-file-in-slurm-to-track-progress/119092)

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**Author:** [@pulk\_jain](https://discourse.julialang.org/u/pulk_jain)\
**Replies:** 0\
**Last updated:** [September 5, 2024, 10:21pm UTC](https://discourse.julialang.org/t/writing-parallel-worker-output-to-out-file-in-slurm-to-track-progress/119092 "2024-09-05T22:21:50Z")

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I am solving an ODE with different initial conditions using EnsembleDistributed on a cluster. I’d like to track the progress of the ensemble calculations. To do that, I wrote the following output and reduction functions: …

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## [Why does the plot of EnsembleProblem differ from the original ODEProblem?](https://discourse.julialang.org/t/why-does-the-plot-of-ensembleproblem-differ-from-the-original-odeproblem/118415)

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**Author:** [@homocomputeris](https://discourse.julialang.org/u/homocomputeris)\
**Replies:** 2\
**Last updated:** [August 29, 2024, 5:59pm UTC](https://discourse.julialang.org/t/why-does-the-plot-of-ensembleproblem-differ-from-the-original-odeproblem/118415 "2024-08-29T17:59:44Z")

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I assume that if I don’t change the problem in EnsembleProblem, the EnsembleSummary should produce the same plot as the original ODEProblem solution. Simple example: module test using Plots, StatsPlots using LinearAlg…

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## [Using derived quantities from previous time step](https://discourse.julialang.org/t/using-derived-quantities-from-previous-time-step/118642)

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**Author:** [@pulk\_jain](https://discourse.julialang.org/u/pulk_jain)\
**Replies:** 11\
**Last updated:** [August 28, 2024, 10:29pm UTC](https://discourse.julialang.org/t/using-derived-quantities-from-previous-time-step/118642 "2024-08-28T22:29:54Z")

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What is the best way to use a derived value (not part of the solution vector) from the previous time step. I was thinking of passing it like a parameter and updating at each time. I did something like: #Approach1 funct…

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## [Warning installing OrdinaryDiffEq](https://discourse.julialang.org/t/warning-installing-ordinarydiffeq/118573)

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**Author:** [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Replies:** 5\
**Last updated:** [August 24, 2024, 9:58pm UTC](https://discourse.julialang.org/t/warning-installing-ordinarydiffeq/118573 "2024-08-24T21:58:06Z")

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When installing OrdinaryDiffEq v6.88.0 I get the following warning: ┌ OrdinaryDiffEq │ WARNING: could not import OrdinaryDiffEqCore.strip\_interpolation into OrdinaryDiffEq Furthermore there seams to be a precompilatio…

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## [How to install OrdinaryDiffEq?](https://discourse.julialang.org/t/how-to-install-ordinarydiffeq/118572)

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**Author:** [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Replies:** 3\
**Last updated:** [August 24, 2024, 8:33pm UTC](https://discourse.julialang.org/t/how-to-install-ordinarydiffeq/118572 "2024-08-24T20:33:46Z")

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I heard that this package was split into many smaller packages. How can I install less solvers? I only need: DFBDF DImplicitEuler KenCarp4 Any idea?

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## [Understanding how to use adaptive solver when dt is in the equations](https://discourse.julialang.org/t/understanding-how-to-use-adaptive-solver-when-dt-is-in-the-equations/117520)

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**Author:** [@dbox](https://discourse.julialang.org/u/dbox)\
**Replies:** 2\
**Last updated:** [July 26, 2024, 3:46pm UTC](https://discourse.julialang.org/t/understanding-how-to-use-adaptive-solver-when-dt-is-in-the-equations/117520 "2024-07-26T15:46:50Z")

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Hi, I’m trying to solve a system of equations where some of the terms have explicit dependence on dt. The way round this I am using is passing dt as a parameter: params = Dict(:dt =\> dt) params = NamedTuple(params) b…

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