Open new device and set up for multiple plots, output to screen or PDF if desired.
pl(n,r,c,h,w,mar,file,title)
Number of plots per page (1-25). When specified, this parameter takes precedence and the default settings for r and c are used (the r and c options below are ignored).
Number of rows of plots.
Number of columns of plots.
Height of new page (a.k.a. "device").
Width of new page (a.k.a. "device").
A numerical vector of the form c(bottom, left, top, right) which gives the margin size specified in inches.
PDF file name, in quotes. If a file name is not designated, then the plot is output to the screen instead.
Plot title (must be in quotes)