# command file for gnuplot to show
#   diagonal matrix elements
#   and eigenvalues  
#   for the case of n=3  matrices
#
plot "eigenvals" using 1:2 with lines \
     ,"eigenvals" using 1:3 wi li\
     ,"eigenvals" using 1:4  wi li \
     ,"diagonals" using 1:2 with linespoints \
     ,"diagonals" using 1:3 with linespoints \
     ,"diagonals" using 1:4 with linespoints

# command file for gnuplot to show
#   diagonal matrix elements
#   and eigenvalues  
#   for the case of n=3  matrices
#
plot "eigenvals" using 1:2  \
     ,"eigenvals" using 1:3 \
     ,"eigenvals" using 1:4  \
     ,"diagonals" using 1:2 with lines \
     ,"diagonals" using 1:3 with lines \
     ,"diagonals" using 1:4 with lines

POSTSCRIPT
To copy the existing picture to a PostScript file:
(To produce an encapsulated postscript file)
--------------
set terminal postscript eps monochrome "Courier"  18
set output "fiename.eps"  # otherwise writes the postscript into the screen
set size 1.8,1       # for plots which have a long x-axis
replot
set terminal x11     # closes fiename.eps and comes back to X11
replot
--------------
 General Gnuplot 
  Gnuplot Task 1
  Gnuplot Task 3
  Gnuplot Task 4
  Functions in Gnuplot (and Fit) 
Index