$10 Array environment,examples$
$left( egin{array}{cc} 2 au & 7phi-frac5{12} \ 3psi & frac{pi}8 end{array} ight) left(egin{array}{c} x \ y end{array} ight) mbox{and} left[ egin{array}{cc|r}3 & 4 & 5 \ 1 & 3 & 729 end{array} ight]$
$f(z) = left { egin{array}{rcl} overline{overline{z^2}+cos z} & mbox{for} & |z|<3 \ 0 & mbox{for} & 3leq|z|leq5 \ sinoverline{z} & mbox{for} & |z|>5end{array} ight.$