# Stability of system of periodic delay differential equations
**URL:** https://discourse.julialang.org/t/stability-of-system-of-periodic-delay-differential-equations/68904
**Category:** General Usage
**Tags:** diffeq, numerics, differentialequation
**Created:** [September 29, 2021, 6:01am UTC](https://discourse.julialang.org/t/stability-of-system-of-periodic-delay-differential-equations/68904 "2021-09-29T06:01:56Z")
**Posts on this page:** 2
**Page:** 1
### Author:  [@ANasc](https://discourse.julialang.org/u/ANasc)
#### Post date: [September 29, 2021, 6:01am UTC](https://discourse.julialang.org/t/stability-of-system-of-periodic-delay-differential-equations/68904/1 "2021-09-29T06:01:56Z")
Hi All,
I want to analyze the stability of a system of delay differential equations. I have tried to dive into some of the literature on this but frankly it’s over my head mathematically. I have tried to implement a published numerical routine to calculate Floquet exponents for a system of DDEs, but I don’t fully trust my implementation. Does anyone know of any Julia packages that could achieve this? NEP-PACK.jl seems like it could be promising, but I thought I’d ask for some advice before I dive into that package.
I asked a similar question over at stackexchange ([numerics - Floquet theory for periodic delay differential equations: current numerical routines - Computational Science Stack Exchange](https://scicomp.stackexchange.com/questions/40131/floquet-theory-for-periodic-delay-differential-equations-current-numerical-rout)), but I understand this is a pretty niche question so I thought I’d ask here as well. Any help would be greatly appreciated.
Thanks!
---
### Author:  [@ChrisRackauckas](https://discourse.julialang.org/u/ChrisRackauckas)
#### Post date: [September 29, 2021, 10:49am UTC](https://discourse.julialang.org/t/stability-of-system-of-periodic-delay-differential-equations/68904/2 "2021-09-29T10:49:40Z")
We don’t have a method for calculating Floquent exponents in DelayDiffEq.jl, so I think you can use the solvers if you need one, but then the analysis of the solution would need to be hand-rolled.