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2 votes
2 answers
185 views

Orthonormal solution of overdetermined linear equations

I have a two matrices $A$ and $B$ in $\mathbb{R}^{m \times n }$ ($m \gg $ n) such that there exists an orthonormal matrix $X \in \mathbb{R}^{n \times n }$, such that: $$AX = B$$ Given that $X$ is ...
user36313's user avatar
  • 123
2 votes
1 answer
3k views

Number of 5x5 matrix permutations without repetitions in rows or columns

Context In the boardgame Azul, your goal is to complete as much as possible of a $5\times5$ board by placing 25 tiles of 5 different colours (5 tiles of each colour) so that no colour appears twice in ...
ami232's user avatar
  • 123
1 vote
5 answers
639 views

Solution for $Xa + X^Tb = c$ where $X^TX = I$? [closed]

There are three known $n\times1$ vectors: $a, b, c$, along with one unknown $n\times n$ matrix: $X$. I am only interested in the $n={2,3}$ cases. $X$ is $2\times 2$ or $3\times 3$ rotation matrix ...
Kevin Welsh's user avatar
6 votes
1 answer
332 views

How can I solve an orthogonal-constrained Sylvester equation?

I am currently facing a Sylvester equation $AX+XB = C$ where $A$, $B$, $C$ are all symmetric and a special constraint here is that $X$ should be orthogonal. The Sylvester equation itself may not ...
lisi's user avatar
  • 101
2 votes
2 answers
664 views

On $XX'=I$ such that $AX=XB$ is true when $A,B\in\{0,1\}^{n\times n}$

Given real symmetric matrices $A,B\in\{0,1\}^{n\times n}$ is it true that $$AX=XB$$ has a solution of form $X$ a permutation matrix iff a solution with $XX'=I$ exists? We are over reals. It is clear ...
Turbo's user avatar
  • 13.9k