how to set an intervall to a given angle?

I have an assignment, where I have to set an intervall for a given angle x to 0<=x<=40pi? How do I do that? The answer is apparently x=0:pi/1000:40*pi, where does pi/1000 come from?

Answer 1

[John]

pi/1000 is the step size between points in the vector starting at 0 and ending at 40*pi.