T = 10;
f3[x_] := Sign[Sin[(2*\[Pi]*x)/T]]
![enter image description here](https://community.wolfram.com//c/portal/getImageAttachment?filename=52451.JPG&userId=2803344)
a) Plot[f3[x], {x, -10, 10}]
![enter image description here](https://community.wolfram.com//c/portal/getImageAttachment?filename=20511.JPG&userId=2803344)
b) `Plot[f3[x], {x, -10, 10}, Exclusions -> None]
`
But to include also the points x=-10 and x=10, i.e. the ends of the function definition interval, how can it be done?
![enter image description here](https://community.wolfram.com//c/portal/getImageAttachment?filename=102721.JPG&userId=2803344)
Thank you.
Attachments: