# Tagged Questions

112 views

### Fast algorithm for approximating Eigenvalue distribution of large sparse matrix

I am interested in the eigenvalue distribution of a huge $2^{16}$x$2^{16}$ Hermitian sparse matrix with spectrum contained in $[-1,1]$. That is I don't need to know all eigenvalues exactly, but rather ...
64 views

### How to quickly approximate the eigenvectors of a symmetric matrix

Given a symmetric $n \times n$ matrix $A$, is there any algorithm that can quickly approximate all of its eigenvectors? By "quickly", I mean with time complexity less than $\mathcal{O}(n^3)$.
127 views

### Computing the number of positive and negative eigenvalues

Given a $n \times n$ symmetric matrix $A$ with integers as entries I would like to compute the number of strictly negative $\rm{nn}(A)$ and positive $\rm{np}(A)$ eigenvalues of $A.$ My question is ...
154 views

### Algorithm of extract eigenvalue and eigenvector from matrix using lower triangular matrix

I want to compute the eigenvalue of a matrix with this transform: $$\text{BaseMatrix}\rightarrow \text{LowerTrangularMatrix}$$ and my algorithm of this transform is this: ...
165 views

### Determine direction of eigenvector

Suppose that $A \in \mathbb{R}^{n \times n}$ and $B \in \mathbb{R}^{n \times m}$ are integer matrices. Let $P$ be the unbounded polytope in $\mathbb{R}^n$ given by $$B \cdot x \geq 0$$ As there is no ...
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### Is the QR algorithm for computing eigenvalues efficient for today's standards?

I was looking at the QR factorization algorithm of a matrix to approach eigenvalues. At the Wikipedia page they state that it was developed in the 50's and took over the LR algorithm. They also state ...