[Scilab-users] Why window() provides only symmetric weighting?

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fmiyara fmiyara
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[Scilab-users] Why window() provides only symmetric weighting?


Dear All,

I wonder why windowing functions such as Hann, Hamming, etc., provided by window(), are only symmetric.

When used for spectral analysis by subsequent use of fft(), the periodic weighting is better than the symmetric one. The symmetric window is mainly used in the design of FIR filters, which I guess is a less frequent application than spectral analysis.

While it is true that an easy workaround to get a periodic window of length n is, for instance

w =
window("hn", n+1)(1:$-1);

a syntax such as this

w =
window("hn", n, "per");

would be easier. Setting "sym" as the default option, no backward compatibility issues would possibly arise.

Regards,

Federico Miyara

Libre de virus. www.avast.com

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fmiyara fmiyara
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Re: Why window() provides only symmetric weighting?


Dear all,

Just in case somebody finds this useful, I'm attaching a proposal of a modified version of the function window() which includes three new window functions: Blackman, Blackman-Harris and one out of many different flat-top windows. It also allows a new argument, opt, which can be either "per" for periodic option or "sym" or any other value (or no value) for triggering the default symmetric option.

If there were interest, several other windows could be easily added.

Regards,

Federico Miyara


On 11/02/2021 04:12, Federico Miyara wrote:

Dear All,

I wonder why windowing functions such as Hann, Hamming, etc., provided by window(), are only symmetric.

When used for spectral analysis by subsequent use of fft(), the periodic weighting is better than the symmetric one. The symmetric window is mainly used in the design of FIR filters, which I guess is a less frequent application than spectral analysis.

While it is true that an easy workaround to get a periodic window of length n is, for instance

w =
window("hn", n+1)(1:$-1);

a syntax such as this

w =
window("hn", n, "per");

would be easier. Setting "sym" as the default option, no backward compatibility issues would possibly arise.

Regards,

Federico Miyara

Libre de virus. www.avast.com

_______________________________________________
users mailing list
[hidden email]
http://lists.scilab.org/mailman/listinfo/users


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