The functions named above simply print the following message.
Polygon geometry computations in spatstat
(such as computing the intersection or union of two polygons)
currently depend on the package gpclib.'gpclib' has a restricted licence which explicitly forbids commercial use.
Accordingly, in spatstat (versions 1.17-1 and later)
the code which depends on gpclib can be either enabled or disabled.
By default, spatstat does NOT use gpclib.
In this mode, polygon geometry computations will be executed by
converting the polygons to binary pixel images (`masks'), so that
the result of the intersection or union will be a binary pixel mask.
If you are covered by the gpclib licence, you can enable the use
of gpclib inside spatstat by typing
spatstat.options(gpclib=TRUE).
To check whether gpclib is currently enabled or disabled, type
spatstat.options("gpclib").