x=1:100
y1 = x
y2 = x^(1/2)
y3 = x^(1.2)
# first plot - builds plot window
plot(x,y1,col="blue",type="l",lwd=2)
# add another line
points(x,y2,col="green",type="l",lwd=2)
# add a thid line
points(x,y3,col="orange",type="l",lwd=3)
# note that the first plot call sets the x & y axis limits.
# These may need to be adjusted.