Hi, The scipy.signal.iirdesign function accepts different filter types like 'butter' or 'ellip' (cf. http://docs.scipy.org/doc/scipy-0.14.0/reference/generated/scipy.signal.iird...). However, it fails with the ftype 'bessel': ValueError: bessel does not have order selection. Use iirfilter function. This error is triggered at this line of code: https://github.com/scipy/scipy/blob/master/scipy/signal/filter_design.py#L64... So in practice, the iirdesign function cannot accept the 'bessel' type. Shouldn't we remove it from the docstring ? Or is this a pedagogical error, put here on purpose ? best, Pierre
On Tue, Dec 2, 2014 at 12:52 PM, Pierre Haessig <pierre.haessig@crans.org> wrote:
Hi,
The scipy.signal.iirdesign function accepts different filter types like 'butter' or 'ellip' (cf.
http://docs.scipy.org/doc/scipy-0.14.0/reference/generated/scipy.signal.iird... ).
However, it fails with the ftype 'bessel': ValueError: bessel does not have order selection. Use iirfilter function.
This error is triggered at this line of code:
https://github.com/scipy/scipy/blob/master/scipy/signal/filter_design.py#L64...
So in practice, the iirdesign function cannot accept the 'bessel' type. Shouldn't we remove it from the docstring ? Or is this a pedagogical error, put here on purpose ?
I'm not sure what that's supposed to teach. It would be good to remove 'bessel' from the docs. Also, iirdesign() has the impressive number of zero tests. Care to send a PR for this? Cheers, Ralf
On 02/12/14 12:52, Pierre Haessig wrote:
So in practice, the iirdesign function cannot accept the 'bessel' type. Shouldn't we remove it from the docstring ? Or is this a pedagogical error, put here on purpose ?
Looking at the code, it seems the problem is that there is no 'besselord' function. Cf. buttord, cheb1ord, cheb2ord, ellipord and the filter_dict. I am not sure if this is a deliberate omission or not. Sturla
Le 04/12/2014 14:36, Sturla Molden a écrit :
Looking at the code, it seems the problem is that there is no 'besselord' function. Cf. buttord, cheb1ord, cheb2ord, ellipord and the filter_dict. I am not sure if this is a deliberate omission or not. It seems there is none in Matlab too http://www.mathworks.com/help/signal/ug/iir-filter-design.html
I'm not familiar enough with Bessel filters to know if order estimation is possible or not for this class. best; Pierre
On 05/12/14 13:20, Pierre Haessig wrote:
It seems there is none in Matlab too http://www.mathworks.com/help/signal/ug/iir-filter-design.html
I'm not familiar enough with Bessel filters to know if order estimation is possible or not for this class.
Neither am I. Sturla
On Fri, Dec 5, 2014 at 1:26 PM, Sturla Molden <sturla.molden@gmail.com> wrote:
On 05/12/14 13:20, Pierre Haessig wrote:
It seems there is none in Matlab too http://www.mathworks.com/help/signal/ug/iir-filter-design.html
I'm not familiar enough with Bessel filters to know if order estimation is possible or not for this class.
Neither am I.
Same here. Given that Matlab doesn't have it, I'd guess no though. Ralf
participants (3)
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Pierre Haessig -
Ralf Gommers -
Sturla Molden