Fourier Transform of e-x*e-(x*coswt) w.r.t Frequency

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SUMMARY

The discussion focuses on performing a Fourier Transform on the function \( e^{-x} e^{-x \cos(\omega t)} \) with respect to frequency, where \( x \) is a constant derived from the parameters \( q, b, \) and \( k \). The transformation is necessary to analyze the function's behavior in the frequency domain, particularly in the context of simple harmonic motion (SHM). The participants clarify the function's formulation and confirm the need to evaluate the integral \( \hat{F}(\omega) = \int_{-\infty}^{\infty} e^{-\frac{q^2}{bk} \sin^2(\frac{wt}{2})} e^{-i \omega t} dt \) to achieve the desired frequency representation.

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Homework Statement


it's related with SHM.its a trivial question.and it's definitely got an ans.i need to do Fourier transformation for
e(iwt) e-(q**2/bk(2sin**2(wt)/2))dt.
btw the limits -inf to +inf.whereb=kt,k=boltzmannconst.w=(k/m)**.5(k here is spring const.)do Fourier transform and get it in terms of frequency


Homework Equations


that"s the only eqnbut can be modified to e-x*e-(x*coswt) where x=const.
("though some friends say it'll result in error function")

The Attempt at a Solution



e-(q**2/bk(2sin**2(wt)/2))
=e-(q**2/bk(1-coswt)) (taking q**2/bk=const.say x)
=e-(x(1-coswt))
=e-x*e-(x*coswt)
 
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It's really hard to read the function you're trying to calculate the FT for. Are you saying that the function is

[tex]f(t) = \exp{\left(-\frac{q^2}{bk} \frac{2\sin^2(wt)}{2}\right)}[/tex]

and you want to calculate the Fourier transform?

[tex]\hat{F}(\omega) = \int_{-\infty}^{\infty} \exp{\left(-\frac{q^2}{bk} \frac{2\sin^2(wt)}{2}\right)} \exp{(-i \omega t)} dt[/tex]
 
Last edited:
cepheid said:
It's really hard to read the function you're trying to calculate the FT for. Are you saying that the function is

[tex]f(t) = \exp{\left(-\frac{q^2}{bk} \frac{2\sin^2(wt)}{2}\right)}[/tex]

and you want to calculate the Fourier transform?

[tex]\hat{F}(\omega) = \int_{-\infty}^{\infty} \exp{\left(-\frac{q^2}{bk} \frac{2\sin^2(wt)}{2}\right)} \exp{(-i \omega t)} dt[/tex]

"yes".
the given eqn is
"e-(2q^2/bk(sin^2(wt/2)))

where b=kT,T=absolute temp,k=bolzmann const. and w=(k/m)^(1/2) t=time period.

the above fn. depends on time.i have to apply Fourier transform to convert it into "w" frequency.

the alternate method i came up with is by treating "q,b,w" as const. say"x"
and converting sin^2(wt/2) as "1-coswt"

so the final eqn became e-(x(1-coswt))
((e-x)(e(xcoswt))
other wise have to Fourier transform for this eqn.
 

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