Problem with x axis

Greetings! I'm having some trouble understanding the reason why my x-axis in a matlab plot appears the way it does. I've defined a limit for the x-axis variable(from -2 to 2) and in the plot it shows values from 0 to 4000.

This is my code:

clc;
clear all;
clf;
r=1;
ad=-2*r:0.001:2*r;
d=abs(ad);
Ai=2*r*acos(d./(2*r))-(d/2).*((4*r^2)-d.^2).^0.5;
A=Ai/(pi*r^2);
plot(A);
grid

Answer 1

[Honglei Chen]

You need to do

plot(ad,A)

otherwise the x axis is just the indices of elements in A

[Pedro]

It's working. Thanks!