Computes the smallest rectangle containing a set of points.
vector of x coordinates of observed points,
or a 2-column matrix giving x,y coordinates,
or a list with components x,y giving coordinates
(such as a point pattern object of class "ppp".)
(optional) vector of y coordinates of observed points,
if x is a vector.
A window (an object of class "owin").
Given an observed pattern of points with coordinates
given by x and y, this function finds the smallest
rectangle, with sides parallel to the coordinate axes, that contains
all the points, and returns it as a window.