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Re: question relating to FFT [message #65385 is a reply to message #65373]

Mon, 02 March 2009 11:37

pgrigis
Messages: 436
Registered: September 2007

Senior Member

Hu wrote:
> Hi, there
> I try to use FFT function to smooth a curve (an array), and the code
> is like this:
>
>
> FUNCTION FOURIER,ARRAY ;*****FAST FOURIER FLITER
> FILTER=1.0/(1.0+DIST(152)/4.0)^2
> newARRAY=FFT(FFT(ARRAY,-1)*FILTER,1)
> RETURN,newARRAY
> END
>
> when I got an array X (has 152 elements) and use this function like :
>
> Y = FOURIER(X)
>
> I got an result Y with 152 elements, but all the elements are complex
> number, but How can I got an array filled with regular number, not
> complex number?

To get real number,
you can take the REAL_PART or the ABS of your array.
But you are using a very strange filter indeed...

Ciao,
Paolo

>
> I mean, I want to use the result to calculate regression relationship
> with other array.

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[Message index]

		Re: question relating to FFT By: David Fanning on Mon, 02 March 2009 15:30
		Re: question relating to FFT By: pgrigis on Mon, 02 March 2009 15:21
		Re: question relating to FFT By: Hu on Mon, 02 March 2009 14:03
		Re: question relating to FFT By: pgrigis on Mon, 02 March 2009 11:37
		Re: question relating to FFT By: pgrigis on Tue, 03 March 2009 08:14

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