[R] weird behaviour of eigen() (actual example)

[Karim Elsawy]

Hi Thomas,
the matrix V , which produced the anomelous order,is attached as an R
object,

load("V.r")
eigen(V)$values
you'll get the eigen values in reverse order

best regards
Karim

Thomas Lumley wrote:
> 
> On Sun, 9 Nov 2003, Karim Elsawy wrote:
> 
> > I'm using R 1.7.1 under linux redhat
> > it seems that the eigen values produced by eigen() do not follow
> > a consistant order; I mean either ascending or discending
> 
> This is strange, since the source code explicitly sorts them. Can you send
> an actual example?
> 
>         -thomas
> 
> > e.g
> >
> > for one system:
> > eigenV<-eigen(V)
> > >                   print(eigenV$values)
> >  [1] -7.706828e+13 -4.702980e+13 -3.267579e+13 -1.701297e+13
> > -8.041677e+12
> >  [6] -5.707311e+12 -5.053941e+12 -4.774652e+12 -4.280423e+12
> > -3.798905e+12
> > [11] -3.422172e+12 -3.148595e+12 -2.974540e+12 -2.881025e+12
> > -2.730044e+12
> > [16] -2.476652e+12 -2.216184e+12 -1.996965e+12 -1.852241e+12
> > -1.419131e+12
> > [21] -1.307872e+12 -1.248930e+12 -1.244060e+12 -1.092555e+12
> > -1.069742e+12
> > [26] -1.064907e+12 -1.007863e+12 -9.894342e+11 -9.459110e+11
> > -8.017146e+11
> > [31] -5.619008e+11 -5.443052e+11 -3.834215e+11 -7.530864e+10
> > -2.820257e+10
> > [36] -1.757125e+10 -5.503488e+09 -2.225226e+09 -1.106936e+09
> > -1.035204e-05
> >
> > > -7.706828e+13 > -1.035204e-05
> > [1] FALSE
> >
> > for anther system:
> > eigenV<-eigen(V)
> > > print(eigenV$values)
> >  [1] -8.564110e-03 -1.486071e+08 -8.200752e+08 -2.033989e+09
> > -3.166960e+09
> >  [6] -9.511769e+09 -1.067173e+10 -1.207226e+10 -3.779904e+10
> > -6.752452e+10
> > [11] -1.717127e+11 -1.781890e+11 -1.887900e+11 -2.566200e+11
> > -2.908604e+11
> > [16] -4.027630e+11 -4.813731e+11 -5.072795e+11 -7.635460e+11
> > -8.442470e+11
> > [21] -8.938820e+11 -9.533737e+11 -1.038059e+12 -1.155368e+12
> > -1.297694e+12
> > [26] -1.502400e+12 -1.577757e+12 -1.748035e+12 -1.948777e+12
> > -2.234958e+12
> > [31] -2.586261e+12 -2.635164e+12 -2.705431e+12 -2.714573e+12
> > -3.189646e+12
> > [36] -3.313364e+12 -3.405791e+12 -4.951881e+12 -5.396912e+12
> > -5.681758e+12
> > [41] -5.964839e+12 -6.782151e+12 -7.234084e+12 -7.328940e+12
> > -7.421814e+12
> > [46] -8.129555e+12 -8.226702e+12 -9.268597e+12 -1.003589e+13
> > -1.076822e+13
> > [51] -1.136816e+13 -1.456318e+13 -1.903689e+13 -3.804764e+13
> > -6.641937e+13
> > [56] -1.547690e+14
> >
> > > -8.564110e-03 > -1.547690e+14
> > [1] TRUE
> >
> > what worries me now is that whether the order of the eigen vectors
> > follow the
> > corresponding eigen values or not?????
> > THIS IS OF PRIME IMPORTANCE.
> >
> > any help is very much appreciated
> > best regards
> > Karim
> >
> > ______________________________________________
> > R-help at stat.math.ethz.ch mailing list
> > https://www.stat.math.ethz.ch/mailman/listinfo/r-help
> >
> 
> Thomas Lumley                   Assoc. Professor, Biostatistics
> tlumley at u.washington.edu        University of Washington, Seattle