# \#nonlinear

**URL:** https://discourse.julialang.org/tag/nonlinear/537.md

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## [\[ANN\] ResieQuasi.jl v1.0 — ReSiE: simulation and optimisation of sector-coupled energy systems](https://discourse.julialang.org/t/ann-resiequasi-jl-v1-0-resie-simulation-and-optimisation-of-sector-coupled-energy-systems/138739)

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**Author:** [@Heinstein](https://discourse.julialang.org/u/Heinstein)\
**Replies:** 1\
**Last updated:** [August 11, 2026, 5:07pm UTC](https://discourse.julialang.org/t/ann-resiequasi-jl-v1-0-resie-simulation-and-optimisation-of-sector-coupled-energy-systems/138739 "2026-08-11T17:07:54Z")

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Hello Julia community, we are happy to announce ReSiE v1.0, available as the Julia package ResieQuasi.jl. ReSiE is an open-source simulation engine for sector-coupled energy systems at building and district scale. If y…

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## [Monthly meetups kickstart: JuliaDynamics (and beyond!)](https://discourse.julialang.org/t/monthly-meetups-kickstart-juliadynamics-and-beyond/117359)

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**Author:** [@Datseris](https://discourse.julialang.org/u/Datseris)\
**Replies:** 24\
**Last updated:** [September 11, 2025, 12:20pm UTC](https://discourse.julialang.org/t/monthly-meetups-kickstart-juliadynamics-and-beyond/117359 "2025-09-11T12:20:11Z")

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Hey all! Inspired by the JuliaHealth meetings I am going to be organizing and coordinating monthly meetings for the general topic: Dynamical systems, complex systems, nonlinear dynamics, and nonlinear timeseries analysi…

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## [Quickest way to build solution sensitivity information from Ipopt (sIpopt)](https://discourse.julialang.org/t/quickest-way-to-build-solution-sensitivity-information-from-ipopt-sipopt/132144)

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**Author:** [@chensunn](https://discourse.julialang.org/u/chensunn)\
**Replies:** 1\
**Last updated:** [September 6, 2025, 7:31pm UTC](https://discourse.julialang.org/t/quickest-way-to-build-solution-sensitivity-information-from-ipopt-sipopt/132144 "2025-09-06T19:31:36Z")

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I’m trying to use JuMP and Ipopt to get sensitivity information of the optimal solution to certain parameters. This is functionality that already exists in sIpopt (doi:10.1007/s12532-012-0043-2), but I don’t believe that…

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## [Nonlinear boundary conditions in ApproxFun](https://discourse.julialang.org/t/nonlinear-boundary-conditions-in-approxfun/129504)

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**Author:** [@MingjiaYan](https://discourse.julialang.org/u/MingjiaYan)\
**Replies:** 0\
**Last updated:** [May 31, 2025, 3:43pm UTC](https://discourse.julialang.org/t/nonlinear-boundary-conditions-in-approxfun/129504 "2025-05-31T15:43:07Z")

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Hi, I’m trying to solve for the steady state solution of a one-dimensional heat equation describing a nonlinear heat conduction in a finite domain \[0,1\] using ApproxFun.jl: T\_{xx} = 0 subject to a Dirichlet boundary c…

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## [Determinant constraints in JuMP](https://discourse.julialang.org/t/determinant-constraints-in-jump/126664)

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**Author:** [@Rick](https://discourse.julialang.org/u/Rick)\
**Replies:** 1\
**Last updated:** [March 7, 2025, 6:33pm UTC](https://discourse.julialang.org/t/determinant-constraints-in-jump/126664 "2025-03-07T18:33:10Z")

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Hi! I have a question about using imposing determinant as a constraint in JuMP. Currently, I am trying to solve a problem that involve constraints of the form \\det(A) = c \\det(B), where c is a given scalar. A and B a…

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## [Constraints of type MathOptInterface.ScalarNonlinearFunction-in-MathOptInterface.LessThan{Float64} are not supported by the solver](https://discourse.julialang.org/t/constraints-of-type-mathoptinterface-scalarnonlinearfunction-in-mathoptinterface-lessthan-float64-are-not-supported-by-the-solver/126178)

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**Author:** [@leonie25](https://discourse.julialang.org/u/leonie25)\
**Replies:** 7\
**Last updated:** [February 23, 2025, 4:20am UTC](https://discourse.julialang.org/t/constraints-of-type-mathoptinterface-scalarnonlinearfunction-in-mathoptinterface-lessthan-float64-are-not-supported-by-the-solver/126178 "2025-02-23T04:20:46Z")

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I am working on an optimization problem and build a model using Gurobi Optimizer with JuMP. It has some nonlinear constraints: @constraint(model, f\[i\] + func(qe\[i\])\<= M1 \* (1 - x\[(i, j)\]) + f\[j\]) where f, qe, x are non…

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## [AC Optimal Power Flow in Various Nonlinear Optimization Frameworks](https://discourse.julialang.org/t/ac-optimal-power-flow-in-various-nonlinear-optimization-frameworks/78486)

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**Author:** [@ccoffrin](https://discourse.julialang.org/u/ccoffrin)\
**Replies:** 101\
**Last updated:** [November 7, 2024, 1:12pm UTC](https://discourse.julialang.org/t/ac-optimal-power-flow-in-various-nonlinear-optimization-frameworks/78486 "2024-11-07T13:12:00Z")

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As a follow up to my NLP modeling survey post, I am please to announce the release of the Rosetta OPF project. The goal of this project is to highlight the basic technical requirements for solving the kinds of continuous…

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## [Solving nonlinear equations using inexact Newton — seeking recommendations](https://discourse.julialang.org/t/solving-nonlinear-equations-using-inexact-newton-seeking-recommendations/119887)

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**Author:** [@mpf01](https://discourse.julialang.org/u/mpf01)\
**Replies:** 5\
**Last updated:** [September 26, 2024, 7:37pm UTC](https://discourse.julialang.org/t/solving-nonlinear-equations-using-inexact-newton-seeking-recommendations/119887 "2024-09-26T19:37:51Z")

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I’m seeking recommendations for a package for solving a large system of nonlinear equations, allowing for inexact Newton system solves using iterative linear solvers. My Jacobian is symmetric indefinite, and so I hope to…

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## [How would you solve this DAE?](https://discourse.julialang.org/t/how-would-you-solve-this-dae/119303)

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**Author:** [@martru](https://discourse.julialang.org/u/martru)\
**Replies:** 2\
**Last updated:** [September 12, 2024, 4:00pm UTC](https://discourse.julialang.org/t/how-would-you-solve-this-dae/119303 "2024-09-12T16:00:08Z")

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Hi everyone, I’m a new user and I’m struggling to solve this (pictured below) DAE system. I know next to nothing about solvers so I’d appreciate all the help I can get! So far I’ve tried: function f(out, dx, x, p, …

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## [Implicit numerical method using NLsolve.jl](https://discourse.julialang.org/t/implicit-numerical-method-using-nlsolve-jl/118525)

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**Author:** [@khaledharizb](https://discourse.julialang.org/u/khaledharizb)\
**Replies:** 3\
**Last updated:** [August 23, 2024, 11:13am UTC](https://discourse.julialang.org/t/implicit-numerical-method-using-nlsolve-jl/118525 "2024-08-23T11:13:33Z")

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I would like to implement Lobatto IIIA-IIIB which is an implicit method. To do so, a non-linear equations need to be solved. Then I used NLsolve.jl for my problem using NLsolve function NuMethod(fV::Function,fT::Func…

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## [How to solve the non linear Coupled Cluster equations using Inexact Newton with DIIS?](https://discourse.julialang.org/t/how-to-solve-the-non-linear-coupled-cluster-equations-using-inexact-newton-with-diis/115291)

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**Author:** [@Uranium238](https://discourse.julialang.org/u/Uranium238)\
**Replies:** 1\
**Last updated:** [June 16, 2024, 12:02pm UTC](https://discourse.julialang.org/t/how-to-solve-the-non-linear-coupled-cluster-equations-using-inexact-newton-with-diis/115291 "2024-06-16T12:02:09Z")

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I have been trying to solve the Coupled Cluster Amplitude Equations which are a set of non-linear equations using Julia. The aim is to find cluster amplitudes tensor T2 such that the residual tensor (defined below) is ze…

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## [Multi-core parallel support for JuMP supported solvers?](https://discourse.julialang.org/t/multi-core-parallel-support-for-jump-supported-solvers/112392)

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**Author:** [@charshaw](https://discourse.julialang.org/u/charshaw)\
**Replies:** 26\
**Last updated:** [May 8, 2024, 9:38am UTC](https://discourse.julialang.org/t/multi-core-parallel-support-for-jump-supported-solvers/112392 "2024-05-08T09:38:02Z")

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I am looking for advice on how to enable solver parallelization when using JuMP on a high performance computing cluster. I have read this very informative page, but it is mostly about running many JuMP models in parallel…

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## [How to employ nlsolve() to a function which has parameters which are difficult to calculate](https://discourse.julialang.org/t/how-to-employ-nlsolve-to-a-function-which-has-parameters-which-are-difficult-to-calculate/115126)

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**Author:** [@Uranium238](https://discourse.julialang.org/u/Uranium238)\
**Replies:** 3\
**Last updated:** [June 4, 2024, 11:31am UTC](https://discourse.julialang.org/t/how-to-employ-nlsolve-to-a-function-which-has-parameters-which-are-difficult-to-calculate/115126 "2024-06-04T11:31:58Z")

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Basically, I am trying to solve the Coupled Cluster Equations using Julia and the package NLsolve which can be used to solve such nonlinear equations. My initial strategy was to define a function as follows that accepts …

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## [Parameter bounds and confidence intervals in LsqFit.jl?](https://discourse.julialang.org/t/parameter-bounds-and-confidence-intervals-in-lsqfit-jl/113366)

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**Author:** [@PeX](https://discourse.julialang.org/u/PeX)\
**Replies:** 1\
**Last updated:** [April 23, 2024, 7:40am UTC](https://discourse.julialang.org/t/parameter-bounds-and-confidence-intervals-in-lsqfit-jl/113366 "2024-04-23T07:40:03Z")

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HI all, I’m trying to use LsqFit.jl to fit a model in the form of: model(t, p) = @. p\[1\] \* t^3 + p\[2\] \* t + p\[5\]\*sin(2\*π\*p\[3\]\*t + p\[4\]) However, I need p\[4\] to be strictly between 0 and pi. Is it possible to do it? I…

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## [Tips for Estimating Non-linear Latent SDE](https://discourse.julialang.org/t/tips-for-estimating-non-linear-latent-sde/104326)

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**Author:** [@dleather](https://discourse.julialang.org/u/dleather)\
**Replies:** 1\
**Last updated:** [April 7, 2024, 1:42pm UTC](https://discourse.julialang.org/t/tips-for-estimating-non-linear-latent-sde/104326 "2024-04-07T13:42:20Z")

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I was hoping to use Turing.jl alongside DifferentialEquations.jl to estimate a partially observable SDE via quasi-likelihood methods. Being new to continuous-time models, I was hoping to get some suggestions on the most …

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## [How can I use NonlinearSolve.jl with matrix functions?](https://discourse.julialang.org/t/how-can-i-use-nonlinearsolve-jl-with-matrix-functions/112379)

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**Author:** [@homocomputeris](https://discourse.julialang.org/u/homocomputeris)\
**Replies:** 8\
**Last updated:** [April 2, 2024, 11:06am UTC](https://discourse.julialang.org/t/how-can-i-use-nonlinearsolve-jl-with-matrix-functions/112379 "2024-04-02T11:06:52Z")

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I want to use NonlinearSolve.jl with matrix functions, something like: using NonlinearSolve using LinearAlgebra dim = 2 function f(u, p) return exp(u) - Matrix{Float64}(I(dim)) end u0 = rand(dim, dim) \* 0.01 p = n…

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## [Multiplication of matrix expression and variables leads to stack overflow and matmul error](https://discourse.julialang.org/t/multiplication-of-matrix-expression-and-variables-leads-to-stack-overflow-and-matmul-error/111760)

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**Author:** [@Rahul\_Narwar](https://discourse.julialang.org/u/Rahul_Narwar)\
**Replies:** 2\
**Last updated:** [March 18, 2024, 12:00pm UTC](https://discourse.julialang.org/t/multiplication-of-matrix-expression-and-variables-leads-to-stack-overflow-and-matmul-error/111760 "2024-03-18T12:00:10Z")

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I have an optimal orbital transfer problem: h = 2 n = 6 m = 3 model = Model(NLopt.Optimizer) set\_optimizer\_attribute(model, "algorithm", :AUGLAG) local\_optimizer = NLopt.Opt(:LD\_LBFGS, n\*(h+1) + m\*h) local\_optimizer.xt…

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## [Nonconvex and Matrix Variables](https://discourse.julialang.org/t/nonconvex-and-matrix-variables/82056)

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**Author:** [@chupin](https://discourse.julialang.org/u/chupin)\
**Replies:** 9\
**Last updated:** [March 11, 2024, 11:20pm UTC](https://discourse.julialang.org/t/nonconvex-and-matrix-variables/82056 "2024-03-11T23:20:01Z")

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Is there any way to deal with matrix variables with Nonconvex lib ? I tried something like: using Nonconvex Nonconvex.@load Ipopt f(x) = sqrt(x\[2,2\]) g(x, a, b) = (a\*x\[1,2\] + b)^3 - x\[2,1\] model = Model(f) addvar!(mo…

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## [How to solve a large quadratic programming problem](https://discourse.julialang.org/t/how-to-solve-a-large-quadratic-programming-problem/111200)

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**Author:** [@aris](https://discourse.julialang.org/u/aris)\
**Replies:** 39\
**Last updated:** [March 9, 2024, 6:10pm UTC](https://discourse.julialang.org/t/how-to-solve-a-large-quadratic-programming-problem/111200 "2024-03-09T18:10:58Z")

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Hello everyone, I was looking for the most appropriate way to solve the following minimization problem in Julia. \\arg\\min ||g-K f||^2+α||f||^2\\equiv \\arg\\min \\frac{1}{2}f^T(K^T K+αI)f-g^TKf s.t. f\\geq0 (where K,I a…

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## [Comparing non-linear least squares solvers](https://discourse.julialang.org/t/comparing-non-linear-least-squares-solvers/104752)

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**Author:** [@user664303](https://discourse.julialang.org/u/user664303)\
**Replies:** 37\
**Last updated:** [March 5, 2024, 9:34am UTC](https://discourse.julialang.org/t/comparing-non-linear-least-squares-solvers/104752 "2024-03-05T09:34:42Z")

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I’m creating this thread as a resource for people looking to solve non-linear least squares problems in Julia, so they know what tools are available, what features they have and how well they perform. UPDATE: This compa…

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## [Survey of Non-Linear Optimization Modeling Layers in Julia](https://discourse.julialang.org/t/survey-of-non-linear-optimization-modeling-layers-in-julia/78168)

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**Author:** [@ccoffrin](https://discourse.julialang.org/u/ccoffrin)\
**Replies:** 63\
**Last updated:** [February 4, 2024, 10:34pm UTC](https://discourse.julialang.org/t/survey-of-non-linear-optimization-modeling-layers-in-julia/78168 "2024-02-04T22:34:44Z")

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I am doing a survey of the NLP modeling layers in Julia to see which might be applicable to the kinds of problems that I regularly solve. I have the following basic requirements of the modeling layer, Support for non-…

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## [Modeling and solving systems of nonlinear dynamic equations](https://discourse.julialang.org/t/modeling-and-solving-systems-of-nonlinear-dynamic-equations/108556)

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**Author:** [@enzo.salvatore](https://discourse.julialang.org/u/enzo.salvatore)\
**Replies:** 11\
**Last updated:** [January 17, 2024, 3:48pm UTC](https://discourse.julialang.org/t/modeling-and-solving-systems-of-nonlinear-dynamic-equations/108556 "2024-01-17T15:48:08Z")

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I am currently a Ph.D. student in economics, and I am looking to find a way to model and solve dynamic systems of nonlinear equations. The goal is to create a dynamic Computable General Equilibrium (CGE) model in Julia. …

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## [Lsqfit Nonlinear Regression Using Two Parameters: One Parameter Is Stuck At The Initial Parameter Value](https://discourse.julialang.org/t/lsqfit-nonlinear-regression-using-two-parameters-one-parameter-is-stuck-at-the-initial-parameter-value/108001)

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**Author:** [@HNormanW](https://discourse.julialang.org/u/HNormanW)\
**Replies:** 0\
**Last updated:** [December 24, 2023, 8:53am UTC](https://discourse.julialang.org/t/lsqfit-nonlinear-regression-using-two-parameters-one-parameter-is-stuck-at-the-initial-parameter-value/108001 "2023-12-24T08:53:48Z")

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Hi, I’m trying to run a nonlinear regression fit for a perturbation function, but it seems to only fit one of my two parameters. The perturbation function is for modeling grating efficacy curves, with wavelength as the …

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## [PhD Position in Climate, Clouds, Causal Graphs with Julia](https://discourse.julialang.org/t/phd-position-in-climate-clouds-causal-graphs-with-julia/105942)

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**Author:** [@Datseris](https://discourse.julialang.org/u/Datseris)\
**Replies:** 0\
**Last updated:** [November 8, 2023, 12:50pm UTC](https://discourse.julialang.org/t/phd-position-in-climate-clouds-causal-graphs-with-julia/105942 "2023-11-08T12:50:09Z")

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Hi all, I’d like to advertise here my first ever funded PhD position. Please feel free to forward it to interested students that have some background in one of: climate, timeseries analysis, nonlinear dynamics, and prog…

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## [Speed up solution of large system of equations](https://discourse.julialang.org/t/speed-up-solution-of-large-system-of-equations/102659)

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**Author:** [@amrods](https://discourse.julialang.org/u/amrods)\
**Replies:** 18\
**Last updated:** [August 19, 2023, 3:19pm UTC](https://discourse.julialang.org/t/speed-up-solution-of-large-system-of-equations/102659 "2023-08-19T15:19:48Z")

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I have a system of equations: \\begin{aligned} & S^m\_{a\_m, e\_m}-\\mu^{0m}\_{a\_m, e\_m}=\\sum\_{a\_m=1}^{46} {\\Pi}\_{a\_m, e\_m, a\_f, e\_f}\\sqrt{S^m\_{a\_m, e\_m} S^f\_{a\_f, e\_f}} \\prod\_{k=0}^{T(a\_m, a\_f)-1}\\left(\\frac{\\mu^{0m}\_{a\_m+k…

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## [BoundaError with NLopt in JuMP with a user-defined function and its gradient](https://discourse.julialang.org/t/boundaerror-with-nlopt-in-jump-with-a-user-defined-function-and-its-gradient/99598)

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**Author:** [@naouess](https://discourse.julialang.org/u/naouess)\
**Replies:** 1\
**Last updated:** [May 30, 2023, 7:28pm UTC](https://discourse.julialang.org/t/boundaerror-with-nlopt-in-jump-with-a-user-defined-function-and-its-gradient/99598 "2023-05-30T19:28:19Z")

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Hello, I am solving an NLP in JuMP with several nonlinear user-defined functions as constraints. I provide the functions and their gradients in the following way: for j in 1:24 register(m, Symbol("myfunc\_$j"), length(…

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## [\[ANN\] Attractors.jl](https://discourse.julialang.org/t/ann-attractors-jl/97961)

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**Author:** [@Datseris](https://discourse.julialang.org/u/Datseris)\
**Replies:** 0\
**Last updated:** [April 26, 2023, 6:21pm UTC](https://discourse.julialang.org/t/ann-attractors-jl/97961 "2023-04-26T18:21:49Z")

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Hello people, I am super proud to announce Attractors.jl and the publication that accompanies the bulk of the package, which just appeared on arXiv. As eluded to in the DynamicalSystems.jl v3 announcement, Attractors.jl…

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## [Implementation of Bennetin's algorithm for Lyapunov exponents](https://discourse.julialang.org/t/implementation-of-bennetins-algorithm-for-lyapunov-exponents/97207)

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**Author:** [@Sh\_166](https://discourse.julialang.org/u/Sh_166)\
**Replies:** 1\
**Last updated:** [April 9, 2023, 5:32pm UTC](https://discourse.julialang.org/t/implementation-of-bennetins-algorithm-for-lyapunov-exponents/97207 "2023-04-09T17:32:56Z")

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I want to calculate the Lyapunov indices for a system - problem is that I can’t get DynamicalSystems.jl to work (described here). Therefore, I decided to do it a much more crude way by writing out the steps myself. Now,…

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## [Error while using DynamicalSystems.jl to solve for a complex nonlinear system](https://discourse.julialang.org/t/error-while-using-dynamicalsystems-jl-to-solve-for-a-complex-nonlinear-system/96976)

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**Author:** [@Sh\_166](https://discourse.julialang.org/u/Sh_166)\
**Replies:** 0\
**Last updated:** [April 2, 2023, 5:38pm UTC](https://discourse.julialang.org/t/error-while-using-dynamicalsystems-jl-to-solve-for-a-complex-nonlinear-system/96976 "2023-04-02T17:38:21Z")

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Hi, I was having quite a bit of trouble with DynamicalSystems.jl. In particular, I would like to implement an elastic double pendulum (so, 3 degrees of freedoms). The problem with this system is that it is nonlinear, se…

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## [Nonlinear optimization using JuMP, The solver does not support nonlinear problems (i.e., NLobjective and NLconstraint)](https://discourse.julialang.org/t/nonlinear-optimization-using-jump-the-solver-does-not-support-nonlinear-problems-i-e-nlobjective-and-nlconstraint/95978)

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**Author:** [@mosby](https://discourse.julialang.org/u/mosby)\
**Replies:** 10\
**Last updated:** [March 13, 2023, 7:30pm UTC](https://discourse.julialang.org/t/nonlinear-optimization-using-jump-the-solver-does-not-support-nonlinear-problems-i-e-nlobjective-and-nlconstraint/95978 "2023-03-13T19:30:14Z")

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I am solving a nonlinear optimization problem using Mosek, I am running the following script model = Model(Mosek.Optimizer) @variable(model, y\[1:n\]) @NLconstraint(model, sum((Ay-b)\[i\]^4 for i=1:m) \<= 1.0) # The constr…

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