% ======================================================

% an array of regions => [xmin ymin xmax ymax]

/bounds {
8 dict begin
/a exch def

/xmax a 0 get 0 get 0 get def
/xmin xmax def
/ymax a 0 get 0 get 1 get def
/ymin ymax def

a {
{
/P exch def
/x P 0 get def
/y P 1 get def
xmax x lt {
/xmax x def
} if
xmin x gt {
/xmin x def
} if

ymax y lt {
/ymax y def
} if
ymin y gt {
/ymin y def
} if

} forall
} forall
[xmin ymin xmax ymax]
end
} def