After set.panel is called, the graphics screen is reset to
put plots according to a m x n table. Plotting starts in
the upper left hand corner and proceeds row by row. After
m x n plots have been drawn, the next plot will erase the
window and start in the 1,1 position again. This function
is just a repackaging for specifying the mfrow argument to
par.
Setting up a panel of plots is a quick way to change the
aspect ratio of the graph (ratio of height to width) or
the size. For example, plotting 2 plots to a page produces
a useful size graph for including in a report. You can
print out the graphs at any stage without having to fill
up the entire window with plots. This function, except for the "relax"
option is equivalent to the S sequence: par( mfrow=c(m,n)).