Boud: the libraries line looks fine in makefile as:
LIBS=-lpgplot -lX11 -L"/usr/X11R6/lib"
FYI, on SUN-s in astro.uni.torun.pl domain every user gets PGPLOT env. variable set to:
PGPLOT=-L/opt/lib -lpgplot -L/usr/openwin/lib -lX11
So the compilation of PGPLOT related stuff may look as this:
f77 -o this_is_my_binary pgplot_related.f $PGPLOT
A.