set terminal x11
plot [x=0:30] [-3:3] cos(x) lt 1 lw 2, 0 title "" lt 0 lw 2
set terminal postscript eps color solid 36
set output "wave.ps"
replot
set terminal x11

set samples 200
plot [x=0:100] [-3.5:5] cos(x) lt 1 lw 2, cos(1.1*x) lt 4 lw 2, cos(x)+cos(1.1*x) lt 3 lw 4, 0 title "" lt 0 lw 2
set terminal postscript eps color solid 30
set output "wave2.ps"
replot
set terminal x11

plot [0:6] [0:5] sqrt(x+1/x)
set terminal postscript eps color solid 36
set output "glass.ps"
replot
set terminal x11

plot [-5:5] [-2:5]cos(x)+cos(2*x)+cos(3*x)+cos(4*x) lt 1 lw 3
set terminal postscript eps color solid 28
set output "peak.ps"
replot
set terminal x1