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6 questions
2
votes
1
answer
512
views
Submatrices of matrices in $\mathrm{SL}(4, \mathbb{Z})$ with all eigenvalues equal to $1$ [closed]
This is a follow-up question to my question from Math Stackexchange (Thank you Dietrich Burde and Michael Burr for the help).
Let $M\in \mathrm{SL}(4, \mathbb{Z})$ with all eigenvalues equal to $1$ (i....
4
votes
1
answer
477
views
Are eigenvalues preserved under derived equivalence?
Let $A$ and $B$ be finite dimensional algebras such that $A$ and $B$ are derived equivalent.
Denote by $C_A$ (resp. $C_B$) the Cartan matrix of $A$ (resp. $B$).
Then does the set of eigenvalues of $...
10
votes
0
answers
237
views
Generalized eigen property of a matrix
Given a $n \times n$ invertible matrix $A$, I am interested in the set
$$
\mathcal{S}(A) = \{ D \textrm{ diagonal matrix } \mid \det(D - A) = 0 \}.
$$
Thus, for all eigenvalues $\lambda_i$, we have $...
2
votes
1
answer
799
views
Relation between LDLT and eigendecomposition of real symmetric matrices
The wikipedia page for Cholesky decomposition says:
For real matrices, the factorization has the form $A = LDL^T$ and is
often referred to as LDLT decomposition. It is
closely related to the ...
3
votes
1
answer
1k
views
The largest eigenvalue of a binary matrix with specific density
I would like to find the largest eigenvalue of an $n \times n$ binary matrix of density $p$, i.e., with $p n^{2}$ ones and $(1-p) n^{2}$ zeros. Any idea or reference is welcome.
3
votes
3
answers
357
views
Can a block matrix with at least 3 zero blocks of different size on the diagonal and 1's everywhere else have only integer eigenvalues?
Let $M=\begin{pmatrix}
\begin{array}{cccccccc}
0 & 0 & 1 & 1 & 1 & 1 & 1 &1\\
0 & 0 & 1 & 1 & 1 & 1 & 1 &1\\
1 & 1 & 0 & 0 & ...