Dear Fahreddın,
I think, the norm of the eigenvectors corresponds to some generic
amplitude. But that is something you cannot extract from the solution of
the eigenvalue problem but it depends on the initial deflection or
velocities.
So I think you should be able to use the normalized values just
Aaah, thanks a lot Lennart, I knew there had to be some logic to Octave's
output, but I couldn't see it...
-=- Olivier
2011/12/21 Lennart Fricke pge08...@studserv.uni-leipzig.de
Dear Fahreddın,
I think, the norm of the eigenvectors corresponds to some generic
amplitude. But that is something
Just to be completely clear, there is no such thing as a
non-normalized eigenvector. An eigenvector is only determined *up to a
scalar normalization*, which is obvious from the eigenvalue equation:
A v = l v
where A is the matrix, l is the eigenvalue, and v is the eigenvector.
Obviously v is
According to this page eigenvectors are normalized with respect to the
second matrix. Do you guys have any idea how that's done?
http://www.kxcad.net/Altair/HyperWorks/oshelp/frequency_response_analysis.htm
If the eigenvectors are normalized with respect to the mass matrix, the
modal mass
I read it like that:
(**T is the transpose)
Let's call M the mass matrix and N the modal mass matrix. Then
X**T*M*X=N. If X (matrix of eigenvectors) is normalized with respect to
M, N is I (unity) so it just mean that X**T*M*X=I. That is what octave
and matlab give you.
For this to be true.
Howdy,
Is it possible to get non-normalized eigenvectors from scipy.linalg.eig(a,
b)? Preferably just by using numpy.
BTW, Matlab/Octave provides this with its eig(a, b) function but I would
like to use numpy for obvious reasons.
Regards,
Fahri
___
I'm probably missing something, but... Why would you want non-normalized
eigenvectors?
-=- Olivier
2011/12/20 Fahreddın Basegmez mangab...@gmail.com
Howdy,
Is it possible to get non-normalized eigenvectors from scipy.linalg.eig(a,
b)? Preferably just by using numpy.
BTW, Matlab/Octave
I am computing normal-mode frequency response of a mass-spring system. The
algorithm I am using requires it.
On Tue, Dec 20, 2011 at 8:10 PM, Olivier Delalleau sh...@keba.be wrote:
I'm probably missing something, but... Why would you want non-normalized
eigenvectors?
-=- Olivier
Hmm... ok ;) (sorry, I can't follow you there)
Anyway, what kind of non-normalization are you after? I looked at the doc
for Matlab and it just says eigenvectors are not normalized, without
additional details... so it looks like it could be anything.
-=- Olivier
2011/12/20 Fahreddın Basegmez
If I can get the same response as Matlab I would be all set.
Octave results
STIFM
STIFM =
Diagonal Matrix
102000000
0 10200000
00 1020000
00
I should include the scipy response too I guess.
scipy.linalg.eig(STIFM, MASSM)
(array([ 3937.15984097+0.j, 3937.15984097+0.j, 3937.15984097+0.j,
3923.07692308+0.j, 3923.07692308+0.j, 7846.15384615+0.j]),
array([[ 1., 0., 0., 0., 0., 0.],
[ 0., 1., 0., 0., 0., 0.],
Hmm, sorry, I don't see any obvious logic that would explain how Octave
obtains this result, although of course there is probably some logic...
Anyway, since you seem to know what you want, can't you obtain the same
result by doing whatever un-normalizing operation you are after?
-=- Olivier
I don't think I can do that. I can go to the normalized results but not
the other way.
On Tue, Dec 20, 2011 at 9:45 PM, Olivier Delalleau sh...@keba.be wrote:
Hmm, sorry, I don't see any obvious logic that would explain how Octave
obtains this result, although of course there is probably
What I don't get is that un-normalized eigenvectors can be pretty much
anything. If you care about the specific output of Matlab / Octave, it
means you understand the particular un-normalization that these programs
use. In that case you should be able to recover it from the normalized
output from
I think I am interested in the non-normalized eigenvectors not the
un-normalized ones. Once the eig function computes the generalized
eigenvectors I would like to use them as they are.
I would think this would be a common request since the normal-mode
frequency response is used in many different
Sorry about that. I don't think that terminology is commonly used. This
is what I mean.
Let's say I solve the equations and compute the eigenvalues and
eigenvectors for the given two matrices. I call these results
non-normalized. Then they can be normalized. Once they are normalized if
I
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