Talk:Floquet theory

I'm no expert in the matter, so I'm not editing anything. Having said that, I think that the top lines can be improved; e.g., making it clear in mathematical language that $A(t+T)=A(t)$, and $A\in {R^{n\times n}}$ as well as $x\in {R^{n\times {1}}}$, or whatever applies. Regards! --Biscay (talk) 10:49, 14 July 2009 (UTC)

This article would be much more helpful if not only the existance of $Q(t)$ and $R$ was claimed but also a way to compute them from $A(t)$, or at least a Fourier mode of $A(t)$, was given.

I have added this to the first paragraph. --DavidOfIthaca — Preceding undated comment added 20:59, 17 July 2024 (UTC)

The theorem is an existence proof; it places a very strict constraint upon the form of solution. Working from the solution in normal form, there are useful proofs of stability. AFAIK there is no general method of actually finding the solution. (CHF (talk) 18:58, 16 March 2009 (UTC))

While analytic solutions are usually not available, numerically $Q$ and $R$ are found from forward integration, repeated QR decomposition and renormalization of column vectors. It is the same procedure that is used in the determination of Lyapunov exponents and Lyapunov vectors for hyperbolic dynamical systems where $A(t)$ is the Jacobian Matrix at a point $r(t)$ of some trajectory (e.g. a periodic orbit). 141.89.116.54 (talk) 08:20, 30 July 2014 (UTC)

Error...

The link to Periodic System points to the Periodic table of elements and should be corrected. I don't know how to edit wikipedia yet so someone else should do that. —Preceding unsigned comment added by Haakkineen (talk • contribs) 10:07, 3 August 2009 (UTC)

The section of applying floquet theory to mathieu functions is not in latex, and somewhat harder to read. —Preceding unsigned comment added by 206.196.164.33 (talk) 00:40, 23 October 2010 (UTC)

Fixed. TomyDuby (talk) 01:34, 25 October 2010 (UTC)

More errors

The article refers to references [1, 2] and [3] but it is not clear to which of the actual references are meant. TomyDuby (talk) 01:37, 25 October 2010 (UTC)

Section removed: copyright violation

I have removed the section Floquet's theorem applied to Mathieu equation. It was a mostly verbatim copy of text from a research article, "Wavelets for Elliptical Waveguide Problems" by Lira et al., and therefore a copyright violation. RockMagnetist(talk) 19:13, 28 July 2015 (UTC)

Different (contradicting?) renderings of a monodromy matrix

The article states that:

$\phi ^{-1}(0)\phi (T)$

constitutes the monodromy matrix. From the definitions of a fundamental matrix given in the article text and of a monodromy matrix in the monodromy-matrix article referred to by the article, I would have expected that the monodromy matrix was given as:

$\phi (T)\phi ^{-1}(0)$

Is the/a monodromy matrix equal to none, one, either or both of these matrices?Redav (talk) 15:13, 27 December 2023 (UTC)