i think it's very simple question, but i'm stuck.
$$A=LQ$$ but, why? $$(A)^{-1}\neq{Q^T}L^{-1}$$
$Q$ - Real orthogonal matrix (colums) $[m\times{n}]$, $n\le{m}$;
$L$ - lower triangular matrix $[m\times{m}]$ with comlex elements:
$$ L = \begin{pmatrix} l_{1} & 0 & 0 &\cdots & 0 \\ l_{2} & l_{1} & 0 &\cdots & 0 \\ l_{3} & l_{2} & l_{1} &\cdots & 0 \\ \vdots & \vdots & \vdots& \ddots & \vdots\\ 0 & 0 & l_{3} & l_{2} & l_{1}\\ \end{pmatrix} $$ Thank you!