Is the Data Set Real or Complex Based on DFT Output?

zak8000
Messages
69
Reaction score
0

Homework Statement


A 8-point data set is transformed with a DFT and the resulting array has values
1,2,3,4,5,6,7,8

was the data set real or complex? why?


Homework Equations





The Attempt at a Solution


kind of confused with this question all i know is the discrete Fourier transform converts a sequence into another. i did i previous question by performing the discrete Fourier transform on a signal which was sampled over a frequency but i don't understand this question.
 
Physics news on Phys.org
Have you learned any properties of the real DFT? One property is that the kth element of the output is the complex conjugate of the (N-k)th element, assuming the elements run from 0 to N-1. It's not an immediately obvious property, but you can easily prove it using the DFT equation.
 
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...

Similar threads

Back
Top