Re: [ojAlgo-user] Eigenvectors of Complex Hermitian Matrix

[Anders P. <an...@op...>]

        final Eigenvalue<ComplexNumber> tmpEvD = EigenvalueDecomposition.makeComplex(true);
        tmpEvD.compute(tmpA);
        final MatrixStore<ComplexNumber> tmpV = tmpEvD.getV();

http://ojalgo.org/generated/org/ojalgo/matrix/decomposition/Eigenvalue.html

According to the docs you cannot trust that the eigenvalues are ordered (descending) when you extract the matrices, but the matrices D and V do of course match.


/Anders


On 26 nov 2013, at 05:06, Kieran Bjergstrom <kn...@ch...> wrote:

> Dear All,
> 
> I'm am attempting to use ojAlgo to find the eigendecomposition of 
> complex hermitian matrices with corresponding eigenvectors; acquiring 
> the eigenvalues has been trivial, however I am unsure as to how to find 
> the eigenvectors.
> 
> From what I can see EigenvalueDecomposition has methods getD and getV, 
> which I expect would provide the eigenvalues with and corresponding 
> eigenvectors, however this requires explicitly instantiating 
> EigenvalueDecomposition - something which I don't understand how to do.
> 
> As it stands, I have the following test code:
> 
> -----
> //saves a bit of space
> static ComplexNumber c(double a, double b){
> 		ComplexNumber z = new ComplexNumber(a,b);
> 		return z;
> 	}
> 
> public static void main(String[] args) {
>         final ComplexNumber[][] tmpData = {{c(1),c(1,-1)},{c(1,1),c(-1)}};
>         ComplexMatrix tmpA = tmpFactory.rows(tmpData);
> 	List<ComplexNumber> s = tmpA.getEigenvalues();
> }
> 
> -----
> 
> Which finds the Eigenvalues. How would one proceed to find the 
> eigenvectors for the ComplexMatrix tmpA, and are these eigenvectors, in 
> general, ordered to correlate with the eigenvalues? If possible I would 
> appreciate a concrete piece of code, as I haven't been able to gleam 
> further understanding from the javadocs.
> 
> Thanks,
> Kieran
> 
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