Sorry, I wasn't asking what's interesting about delta functions -- I've used them as well. I was asking about the document and what's significant about it, sinc

Sorry, I wasn't asking what's interesting about delta functions -- I've used them as well. I was asking about the document and what's significant about it, since it seems quite incomplete (?) and hardly goes into any depth (or breadth for that matter)... there are lots better ones out there so I'm confused why anyone posted this.