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Re: time vs longitude FFT [message #56547 is a reply to message #56542]

Mon, 29 October 2007 14:52

R.G.Stockwell
Messages: 163
Registered: October 2004

Senior Member

<knielsen73@gmail.com> wrote in message
news:1193692469.369318.51960@50g2000hsm.googlegroups.com...
>> kxvalues = findgen(nx)/nx - 1./2
>> kyvalues = findgen(ny)/ny - 1./2

Note, in the above, it shows that the sampling interval is 1.
You should divide by your sampling interval there if it is not 1.

> amp = 10.
> wave_number = 2
> wavelength = float(jmax)/wave_number
> period = 6.8333333
>
> for j=0,jmax-1 do begin
> for n=0,nmax-1 do begin
> data_in[j,n] = amp*sin(2.*!pi*j/wavelength - 2.*!pi*n/period) +$
> amp*.5*cos(2.*!pi*j/wavelength - 2.*!pi*n/period)

for one thing, you are adding 2 out of phase waves here. Remove the
first term (and just use the cos).

Also, do just 1D to ensure that you are calculating the correct
period and freq.

f = 12/len
data = amp*cos(2 !pi f t)

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[Message index]

		Re: time vs longitude FFT By: Kenneth Bowman on Mon, 29 October 2007 10:41
		Re: time vs longitude FFT By: knielsen73 on Mon, 29 October 2007 17:29
		Re: time vs longitude FFT By: R.G.Stockwell on Mon, 29 October 2007 14:54
		Re: time vs longitude FFT By: R.G.Stockwell on Mon, 29 October 2007 14:52
		Re: time vs longitude FFT By: knielsen73 on Mon, 29 October 2007 14:14
		Re: time vs longitude FFT By: R.G.Stockwell on Mon, 29 October 2007 11:41

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