[Numpy-discussion] Re: Dear Robert

2023-02-25 Thread Robert Kern
On Sat, Feb 25, 2023 at 8:17 PM Louis Petingi wrote: > Hi Robert > > Just a follow up. I was able (my student) to get the 1 vector from the 0 > eigenvector. Even though the normalized or this set of eigenvectors will > work we could try the two sets. Not sure if multiplying the unit vectors by >

[Numpy-discussion] Re: Dear Robert

2023-02-25 Thread Louis Petingi
Hi Robert I read somewhere that we can use the unit vector times a scalar for the Friedler eigenvector. Thus, the question is that for the first k-eigenvectors do we multiply the corresponding unit vectors them by the same scalar? That said my feeling is that when applying k-mean on the first

[Numpy-discussion] Re: Dear Robert

2023-02-25 Thread Robert Kern
On Sat, Feb 25, 2023 at 5:33 PM Louis Petingi wrote: > As you mentioned this is a generalization of the Fiedler eigenvector. When > applying spectral clustering, and you want to find the two clusters > then the Fiedler eigenvector tells you how to partition the vertices > (bipartition) so the

[Numpy-discussion] Dear Robert

2023-02-25 Thread Louis Petingi
As you mentioned this is a generalization of the Fiedler eigenvector. When applying spectral clustering, and you want to find the two clusters then the Fiedler eigenvector tells you how to partition the vertices (bipartition) so the normalized cut is minimized. The concept can be generalized to

[Numpy-discussion] Re: non normalised eigenvectors

2023-02-25 Thread Robert Kern
On Sat, Feb 25, 2023 at 4:11 PM Louis Petingi wrote: > Hi Thanks > > Very simply one of the solutions for the zero eigenvalue is the 1 > eigenvector. If I get back this 1 vector, for the 0 eigenvalue then the > other eigenvectors will be in the right format I am looking for. Once > again, the

[Numpy-discussion] Re: non normalised eigenvectors

2023-02-25 Thread Louis Petingi
Hi Thanks Very simply one of the solutions for the zero eigenvalue is the 1 eigenvector. If I get back this 1 vector, for the 0 eigenvalue then the other eigenvectors will be in the right format I am looking for. Once again, the 1 vector is the normalized eigenvector * norm. Best Louis

[Numpy-discussion] Re: non normalised eigenvectors

2023-02-25 Thread David Menéndez Hurtado
On Sat, 25 Feb 2023 at 20:09, Louis Petingi wrote: > Thank you for the reply. I am working with the Laplacian matrix of a graph > which is the Degree matrix minus the adjacency matrix. > The Laplacian is a symmetric matrix and the smallest eigenvalue is zero. > As the rows add it to 0, Lx=0x,

[Numpy-discussion] Re: non normalised eigenvectors

2023-02-25 Thread Robert Kern
On Sat, Feb 25, 2023 at 2:11 PM Louis Petingi wrote: > Thank you for the reply. I am working with the Laplacian matrix of a graph > which is the Degree matrix minus the adjacency matrix. > The Laplacian is a symmetric matrix and the smallest eigenvalue is zero. > As the rows add it to 0, Lx=0x,

[Numpy-discussion] Re: non normalised eigenvectors

2023-02-25 Thread Louis Petingi
Thank you for the reply. I am working with the Laplacian matrix of a graph which is the Degree matrix minus the adjacency matrix. The Laplacian is a symmetric matrix and the smallest eigenvalue is zero. As the rows add it to 0, Lx=0x, and 1 is the resulting vector. The normalized eigenvector is

[Numpy-discussion] Re: non normalised eigenvectors

2023-02-25 Thread Robert Kern
On Sat, Feb 25, 2023 at 11:39 AM wrote: > Dear all, > > I am not an expert in NumPy but my undergraduate student is having some > issues with the way Numpy returns the normalized eigenvectors corresponding > to the eigenvalues. We do understand that an eigenvector is divided by the > norm to get

[Numpy-discussion] Re: non normalised eigenvectors

2023-02-25 Thread Ilhan Polat
Could you elaborate a bit more about what you mean with original eigenvectors? They denote the direction hence you can scale them to any size anyways. On Sat, Feb 25, 2023 at 5:38 PM wrote: > Dear all, > > I am not an expert in NumPy but my undergraduate student is having some > issues with the

[Numpy-discussion] non normalised eigenvectors

2023-02-25 Thread louis . petingi
Dear all, I am not an expert in NumPy but my undergraduate student is having some issues with the way Numpy returns the normalized eigenvectors corresponding to the eigenvalues. We do understand that an eigenvector is divided by the norm to get the unit eigenvectors, however we do need the