It´s not clear what you are trying to do, but there are some bad things here:
1) when you use int command, you dont give the integration variable; i think it will be y.
2) the upper r+d is not a value, but an array. So u better write it like this:
y2= int(b,y, r,r+d(1))
( or some other selection in the array d), instead of yours :
y2= int(b,r,r+d)
By the way, you are using plot for representing 3 2D points (I hope you know that), but they cant barely be visible. You better use:
plot(d,u, 'x')
I hope this will be helpful.
