If r is a number, square(r)
is a shortcut for creating a window object
representing the square
$[0,r] * [0,r]$.
It is equivalent to the command
owin(c(0,r),c(0,r)). If r is a vector of length 2, then
square(r) creates the square with x and y coordinates
ranging from r[1] to r[2].
unit.square creates the unit square
$[0,1] * [0,1]$.
It is equivalent to
square(1) or square() or owin(c(0,1),c(0,1)).
These commands are included for convenience,
and to improve the readability of some code.