Claus,
For me the plurality is not so important - but let's say it's the
wording used in all our educational books (in English) ... just dig
into any Signal Analysis book, etc., and what we're trying to name
here is exactly that, then it would be bad for Scilab to give it a
different name. Renaming something that is universally defined
otherwise is an uphill battle we cannot win.
As I implied earlier, nomenclature could hardly be right or wrong since
it is mostly arbitrary. But there could be more logical or less logical
choices.
When it is well established, it is also a battle that is not worth
fighting, especially if there is some sort of rationale behind it.
Asymmetric window functions is new to me.I googled about window
functions and found (stumbled upon):
https://journals.sagepub.com/doi/pdf/10.1260/1748-3018.9.4.389
This is another kind of asymmetry. "Periodic" window functions are only
slightly asymmetric. I don't think they qualify for the kind of windows
treated in that paper.
Asymmetric windows seem to be a good choice to smooth out the spectrum
if phase response is not important. Scilab doesn't have any asymmetric
function, but if a plan to add new windows were approved, they could be
included along with several more traditional window functions currently
not covered (such as Blackman, Blackman-Harris or a number of flat-tops).
Symmetric windows are used for FIR filter design. Periodic windows are
used for spectrum analysis.
Regards,
Federico Miyara
Conclusion: Asymmetric window functions have a purpose. When there's
asymmetric windows, then there must also be symmetric windows.
Here's a short list of symmetric window functions:
https://mathworld.wolfram.com/ApodizationFunction.html
Best regards,
Claus
On 12-04-2021 17:19, Federico Miyara wrote:
Samuel:
As a general concept, you are right ... but with nuances. The problem
is deciding when something is really wrong and when it is just a
question of opinion or personal preference. It is wrong to say the
Earth is flat, no matter how many people say it. But is it right or
wrong to call something just a conventional name?
For instance: Is it right to call the derivative of a function
"derivative"? Probably not, because "derivative" is a general concept
which seems to have no relationship with its meaning in math.
Probably in its origins it was more related to grammar than to math.
But once established for centuries, it wouldn't be convenient to
change it on the basis that it is "wrong".
By the same token, calling "periodic" a window function obtained from
periodic functions (cosines) whose period is equal to its length
doesn't seem intrinsically wrong to me. Calling it "closed" would be
worse since one immediately thinks either of a closed set, which is
not, or a closed curve, which isn't either.
But even if we found a better word, changing it would very likely
create an unnecessary cognitive dissonance to thousands or millions
of practitioners.
Anyway, if a much better and cristal-clear word (i.e., whose meaning
would be immediately obvious in its context) were found and gained
consensus, no problem to use it instead of "periodic". The important
thing in my proposal was to include in the window() function the
feature, not how we call it.
Regards,
Federico Miyara
On 12/04/2021 04:22, Dang Ngoc Chan, Christophe wrote:
Hello,
De : Federico Miyara
Envoyé : dimanche 11 avril 2021 02:08
Like it or not, I guess these keywords come from Matlab, and as Matlab
still seems to dominate the market, many people, including those
willing to quit Matlab (as I did several years ago), are quite used to
those keywords
I don't agree with this argument.
If a way of doing is wrong, then just keep on going because "everybody does so"
is just an argumentum ad populum
https://en.wikipedia.org/wiki/Argumentum_ad_populum
which is a fallacious argument.
Regards.
--
Christophe Dang Ngoc Chan
Mechanical calculation engineer
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