0
$\begingroup$

How can I tell if a $3 \times 3$ matrix is a reflection? I know that orthogonal matrices have determinants of either $1$ or $-1$. If the determinant is $-1$, then it can possibly be a reflection. How do I prove for sure that the $3 \times 3$ matrix is a reflection?

  • 0
    A reflection matrix would either be a diagonal matrix with $\pm 1$ entries, or an elementary Hermitian (Householder) reflector...2011-11-03

2 Answers 2