[R] Dominant eigenvector displayed as third (Marco Visser)

[Ben Bolker]

 >
 > Marco Visser wrote:
 > > Dear R users & Experts,
 > >
 > > This is just a curiousity, I was wondering why the dominant 
eigenvetor and
eigenvalue
 > > of the following matrix is given as the third. I guess this could 
complicate
automatic selection
 > > procedures.

 > >
 > > Comment: In Matlab the the dominant eigenvetor and eigenvalue
 > > of the described matrix are given as the sixth. Again no idea why.
 > >   
 > ????
 >

  If you want the eigenvalue with the largest REAL PART to be first
(which will be "dominant" in the sense of population dynamics/stability)
then you can just reorder according to

order(-Re(eigen(mat)$values))

  About MATLAB: my guess is that it, too, is ordering
according to modulus -- since the moduli are essentially
all the same, the order will be more or less random
across programs and platforms
(on my Linux machine I got the "dominant" (=largest real part)
eigenvector/value pair 6th, too).

  Ben Bolker