Math people, can you identify these for me?

Factual Questions
1

Can you please identify this for me:

http://www.webhostingtalk.com/images/question1.png
http://www.webhostingtalk.com/images/question3.png
http://www.webhostingtalk.com/images/question2.png

Thanks alot, in advance!

2

Nevermind, thanks. Mods can ya delete?

3

or not… now I do need an answer. Bah. Now if the mods could just delete this post and the one right before it.

4

I’m not a mathematician but #1 is the Euler relation.

Number 3 is derived from #1.

cos x+jsin x = e[sup]jx[/sup]

(e[sup]jx[/sup])[sup]n[/sup] = e[sup]jnx[/sup] = cos nx + jsin nx

5

and question 3 (the second one!) looks like a discrete fourier transform

6

Well the guy got his answer, but if ya’ll want to know:

  1. euler’s identity
  2. de moivre’s theorem
  3. downsampling theorem

In the order I posted them. (Accidentally put 3 before 2… guess I shouldn’t be trying these…)