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Re: question relating to FFT [message #65372 is a reply to message #65371]

Mon, 02 March 2009 15:21

pgrigis
Messages: 436
Registered: September 2007

Senior Member

Hu wrote:
> On Mar 2, 2:37 pm, Paolo <pgri...@gmail.com> wrote:
>> 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.
>>
>>
> Thank you ,and Why do you say it's strange? I want to denoise the
> whole curve( store as array) to make it more reasonable.

Try plot,dist(152)
Does that look like what you want?

Ciao,
Paolo

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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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