Heaviside step function, signal and systems

Jncik
Messages
95
Reaction score
0

Homework Statement


given this discrete time signal

x[n] = u[n] - u[n-6]

find for which n the even part of x is 0

The Attempt at a Solution



the even part is

x' = 1/2(x[n] + x[-n]) = 1/2(u[n] - u[n-6] + u[-n] - u[6-n])

now i find that

u[n] + u[-n] is 2 for n = 0 and 1 for n != 0
u[n-6] + u[6-n] is 2 for n = 6 and 1 for n!=6

let z[n] = u[n] + u[-n]
k[n] = u[n-6] + u[6-n]

we want to find where 1/2 * (z[n] - k[n]) = 0 => z[n] - k[n] = 0

this is
0 for n != 0 and n!=6
1 for n = 0
-1 for n = 6

is this correct? I am new to this thing.. if you can please help me :)
 
Physics news on Phys.org
Your reasoning makes sense to me... is there some reason you suspect that your answer is wrong?
 
diazona said:
Your reasoning makes sense to me... is there some reason you suspect that your answer is wrong?

No not really, I just wasn't 100% sure for my answer, my book didnt really have any answers and i needed to know if i understood these simple concepts.. thanks for your help now I can move on :)
 
Thread 'Need help understanding this figure on energy levels'
This figure is from "Introduction to Quantum Mechanics" by Griffiths (3rd edition). It is available to download. It is from page 142. I am hoping the usual people on this site will give me a hand understanding what is going on in the figure. After the equation (4.50) it says "It is customary to introduce the principal quantum number, ##n##, which simply orders the allowed energies, starting with 1 for the ground state. (see the figure)" I still don't understand the figure :( Here is...
Thread 'Understanding how to "tack on" the time wiggle factor'
The last problem I posted on QM made it into advanced homework help, that is why I am putting it here. I am sorry for any hassle imposed on the moderators by myself. Part (a) is quite easy. We get $$\sigma_1 = 2\lambda, \mathbf{v}_1 = \begin{pmatrix} 0 \\ 0 \\ 1 \end{pmatrix} \sigma_2 = \lambda, \mathbf{v}_2 = \begin{pmatrix} 1/\sqrt{2} \\ 1/\sqrt{2} \\ 0 \end{pmatrix} \sigma_3 = -\lambda, \mathbf{v}_3 = \begin{pmatrix} 1/\sqrt{2} \\ -1/\sqrt{2} \\ 0 \end{pmatrix} $$ There are two ways...
Back
Top