x <- seq(0, 10, by = 0.01)
y1 <- cos(0.4*pi*x)
y2 <- cos((8/5)*pi*x)

plot(x, y1, type = "l", lwd = 2, 
     xaxt = "n", yaxt = "n", 
     xlab = "Time", ylab = "", cex.lab = 1.7, col = 4)
lines(x, y2, lwd = 2, col = 2)

# Fix axes.
x.axis <- seq(0, 10, by = 2)
y.axis <- seq(-1, 1, by = 0.5)
axis(1, at = x.axis, labels = x.axis, cex.axis = 1.7)
axis(2, at = y.axis, labels = y.axis, cex.axis = 1.7)

dev.print(device = postscript, "18.11.eps", horizontal = TRUE)