[SciPy-dev] [SciPy-user] scipy.linalg.eig() returns transposed eigenvector matrix

Alan G Isaac aisaac at american.edu
Tue Nov 15 08:20:22 CST 2005


On Tue, 15 Nov 2005, Pearu Peterson apparently wrote: 
> I am not convinced that getting eigenvectors one-by-one is 
> the most common case of la.eig usage. Sometimes one needs 
> to operate with the whole matrix of eigenvectors and then 
> the mathematically "correct" representation of the 
> eigenmatrix would be more convinient. 

Even though you put "correct" in quotes,
and even though I do not have a strong position on this,
I'd like to caution against the "correct"ness argument
(assuming I have understood it).

Row vectors are perfectly valid left-eigenvectors.
http://en.wikipedia.org/wiki/Eigenvector
We are concerned with the case where left and right 
eigenvectors have the same (normalized) elements,
so we are just trying to pick a convention.

Like you I expect my eigenvectors to be columns,
and I think about them as right eigenvectors.
But others have different expectations apparently.
The problem in this case is perhaps choosing a transparent 
notation.

fwiw,
Alan Isaac





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