Symplectic matrix
= Symplectic matrix
{title2=$A^TJA=J$}
An invertible real matrix preserving the <standard symplectic form>. With $J=\begin{pmatrix}0&I\\-I&0\end{pmatrix}$, it satisfies $A^TJA=J$, equivalently $AJA^T=J$. The first identity describes preservation of the form; the second describes preservation of coordinate <Poisson brackets>.