How do I draw a set of vertical lines in gnuplot?

Question

E.g. if I have a graph and want to add vertical lines at every 10 units along the X-axis.

Answer 1

To elaborate on previous answers about the "every x units" part, here is what I came up with:

# Draw 5 vertical lines
n = 5

# ... evenly spaced between x0 and x1
x0 = 1.0
x1 = 2.0
dx = (x1-x0)/(n-1.0)

# ... each line going from y0 to y1
y0 = 0
y1 = 10

do for [i = 0:n-1] {
    x = x0 + i*dx
    set arrow from x,y0 to x,y1 nohead linecolor "blue" # add other styling options if needed
}