Been a while since my first degree, and I can't seem to solve this kiddy-level question. Please indulge me:
A an orthogonal matrix, D a diagonal matrix.
is it true that $A^TDA = D$ ?
(where $^T$ is the transpose operator) Thanks.
Been a while since my first degree, and I can't seem to solve this kiddy-level question. Please indulge me:
A an orthogonal matrix, D a diagonal matrix.
is it true that $A^TDA = D$ ?
(where $^T$ is the transpose operator) Thanks.
Not true, a simple example: $A=\left(\begin{matrix} 0& 1\\ 1&0 \end{matrix}\right)$, $D=\left(\begin{matrix} 1& 0\\ 0&2 \end{matrix}\right)$.