Questions tagged [eigendecomposition]
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39 questions
1 vote
1 answer
103 views
On the Utility of DFT-Invariant Signals and Their Closed-Form Representations
Let us consider signals (or finite sequences) that are invariant under the Discrete Fourier Transform (DFT). Suppose we are able to obtain a closed-form (explicit) formula for such invariant signals. ...
1 vote
2 answers
359 views
Computing modern spectral estimation techniques with FFTs
This question is a follow-up to this Pisarenko Harmonic Decomposition question. In the answer and comments gathered there, it appears that instead of computing the Pisarenko pseudo-spectrum using the (...
1 vote
1 answer
312 views
Mistake in Python implementation of Pisarenko's harmonic decomposition
I'm trying to implement Pisarenko's Harmonic decomposition in Python and can't get a proper pseudo spectrum revealing the three frequencies of the signal I'm analysing. I tried a few things (using <...
1 vote
0 answers
53 views
Fastest way to track dominant eigenvector of recursively updated correlation matrix
Consider a real vector time series: $\mathbf{x}_k\in{\mathbb{R}}^{N \times 1}$ where $k$ is the sample index. An associated correlation matrix is updated recursively as: $${\bf R}_k = \alpha {\bf R}_{...
2 votes
0 answers
143 views
The Discrete Fourier Transform (DFT) decomposes any signal into four orthogonal signal components
Let $F=\frac{1}{\sqrt{n}}(w^{kl})_{k,l=0}^{n-1}$ be the discrete Fourier matrix of size $n$ where $w=\exp^{-\frac{2\pi i}{n}}$. It is a well-known that $F_n^4 = I_n$ where $I_n$ represents the ...
2 votes
1 answer
170 views
Are complex exponentials the only eigenfunction for arbitrary LTI systems?
After reading a few posts, like this. I know that arbitrary LTI systems always have complex exponential eigenfunctions. And that for specific LTI systems you can also have other types of ...
1 vote
2 answers
191 views
Practical Implications of DFT Eigenvector Formulations
Different sets of eigenvectors for the Discrete Fourier Transform (DFT) are well-established. Are there any potential practical implications associated with deriving explicit formulations for these ...
4 votes
2 answers
399 views
Smallest Eigenvalue in the Derivation of the MUSIC Algorithm
I am seeking clarification on a particular step in the derivation of the MUSIC algorithm as presented in a specific paper. Here, there is an intermediate step I cannot follow and I would appreciate ...
3 votes
0 answers
74 views
Direct and numerically robust conversion from zero-pole to state-space representation
Note: this question was initially asked in a different community. Encouraged by the comments, I decided to cross-post here too. Given (z,p,k) my goal is to convert to a state-space representation (A, ...
3 votes
1 answer
109 views
Why do they say that complex exponentials are eigenfunctions of LTI systems, when there are still transient responses?
Let $$\dot{x} = Ax+Bu$$ $$y = Cx + Du$$ be a linear ODE with $x(0)=0$. Here, I am assume $A$ is invertible. As you can see, the relation $$H:u(.) \mapsto y(.),$$ where $(u(.),y(.))$ is a solution to ...
0 votes
1 answer
70 views
The benefit of Eigendecomposition of DCT and DST
I am Ph.D in pure mathematics and interested in signal processing. Theoretically, any illustration of the eigendecomposition of the discrete trigonometric transforms (DTTs) is worthwhile. Q. What real ...
0 votes
2 answers
88 views
When is the Fourier transform of a periodic discrete signal $\mathcal{F}x[k]$ the same as $x[k]$ up to a diagonal matrix
I am looking for all pairs $(x[n],q)$ where $x[n]$ is a periodic discrete signal with period $N$ and $q$ is a rational number satisfying the following identity: $$\mathcal{F}x[k]=e^{i(q-\frac{\pi k}{...
5 votes
0 answers
187 views
Subspace Methods - Eigenvalues of the Signal Subspace
Subspace frequency estimation methods like MUSIC or ESPRIT decompose the signal correlation matrix into a signal and a noise subspace. Assume the signal model is given by $$\boldsymbol{s} = \...
0 votes
1 answer
115 views
Subspace decomposition
While reading the paper "Perturbation analysis for subspace decomposition with applications in subspace-based algorithms" by Zhengyuan Xu, I came across the decomposition technique called ...
3 votes
2 answers
238 views
Why do we need to estimate eigenvalues?
I am not working in signal processing field, but recently I happen to read a paper which estimates source numbers using Gerschgorin radii, and I feel kind of confused about why we need to estimate ...