Question

Fourier transform

Answer 1

1)let g(x)=f(ax)
find a formula for fourier transform of g(x) ->G(w) in terms of F(w)
2) find fourier transform of \[\large{x^2e^{-x^2}}\]

Answer 2

oooooooooo

Answer 3

This is a brutal question

Answer 4

I'm in Wireless Electronic Communications Eng right now, and we have q's like this...

Answer 5

I'm scared to begin helping you lol... How far into it are you?

Answer 6

well i dont want the solution in signals and systems way,,,
i want it solved the way mathematicians solve it ...
ive taken all fourier analysis,,, but i get confused when im asked to solve it like mathematicians

Answer 7

I get brain bubbles from this dark corner of mathematics... I guess what I'm asking is... Have you attempted solving it yet?

Answer 8

i tried yeah but im not getting it -.-

Answer 9

Lets see your work

Answer 10

u dont have to give me the answer, i just need like a hint or something,, or how to start,,, i never ask for the whole solution,,, if u can just explain to me how to start and give like a hint or something

Answer 11

Basically in fourier transformation your are transforming the function given into another.

Answer 12

The new function is split up into pieces called coefficients of the fourier series. Finding those coefficients themselves is the difficult part because it requires intense integrals. One tip in finding the coeffiecients is that negative functions such as sins can be canceled ( integral will be zero) because of symmetry.

Answer 13

I'm not questioning your motives, Sarah. I'm going to let Romero take it away, because honestly, I 'm not as familiar with the subject. :D (whew! Dodged a bullet there!) Thanks @Romero And thank you @Sarah.L for being a curious student!

Answer 14

@Dyiliq I'm actually not that good at it. I only know how to solve for wave functions (physics). But sara what you can do it use Euler's formula to get sin and cos as the function you are going to transform.

Answer 15

thankyou guys iwill try to do it again, i appreciate u viewing my question:)

Answer 16

Well, hang on there.

Answer 17

I'm going to give you a handful of links that help me with the 'MATH' part of my wireless course, ok? They have been beyond helpful.

Answer 18

that would be amazing:)

Answer 19

http://www.thefouriertransform.com/pairs/gaussian.php
http://en.wikipedia.org/wiki/Gaussian_function
http://www.ericweisstein.com/encyclopedias/books/FourierTransforms.html

Answer 20

Thankyouu :D:D

Answer 21

That last one is seemingly useless

Answer 22

But you can use torrents and other resources to "borrow" the books from the internet community. :D

There inlies my most powerful tools!

Answer 23

you are awesome thanks

Answer 24

http://openstudy.com/study#/groups/MIT%206.002%20Circuits%20and%20Electronics%2C%20Spring%202007

Here is another group on this site that will be better equipped to help with this question.

Answer 25

im in it , and trust me its not really helpful,, im not in mitx .. so its useless for me

Answer 26

Join it, its free.

Answer 27

Free courses, free TEXTBOOKS, free video lectures, I mean WOW about the free-ness of all of that. Canadians are so relaxed....

Answer 28

im doing telecommunication engineerin
and they have like homeworks u should do and i dont have time for it ..
but ill try to join it later

Answer 29

it's worth it, all I'm sayin... :D
You're a very enthusiastic learner. I hope to meet more people like you on this site, Sarah!

Answer 30

Tell your musician friends, if you have any, to join our Music Study group...pretty please.

Answer 31

haha ok i will let them know
:D
Thanks again and again and again :D:D hehe

Answer 32

Always, at the service of those who wish to know and do not know how.

Answer 33

\[g(x)=f(ax)\]
\[\large F(w)=\int_{-\infty}^{\infty} f(x) e^{-jwx}dx\]
now
\[\large G(w)=\int_{-\infty}^{\infty} g(x) e^{-jwx}dx\]
but g(x)=f(ax) so
\[\large G(w)=\int_{-\infty}^{\infty} f(ax) e^{-jwx}dx\]
Now
Let's substitute
\[ax=u\]
so
\[adx=du\]
\[\large G(w)=\frac{1}{a}\int_{-\infty}^{\infty} f(u) e^{-j\frac{w}{a}x}dx\]
Now
\[\large F(w/a)=\int_{-\infty}^{\infty} f(x) e^{-j\frac{w}{a}x}dx\]
so
\[\huge G(w)= \frac{1}{a} F(w)\]

Answer 34

^This is pretty!^
Thinking about this is very spiritually draining...
I'm really glad we have you here @ash2326

Answer 35

who are youuuuuuuuu :P