Re: Butter Command - Maximum Order and Cut Off Frequency - Issues

[Sergei Steshenko]

________________________________
From: Shadders <address@hidden>
To: address@hidden 
Sent: Friday, January 19, 2018 12:34 AM
Subject: Butter Command - Maximum Order and Cut Off Frequency - Issues



Hi,

I am using the butter command as follows :


[b,a] = butter(12, 0.95);


This works. 


If i increase the order to above 64, or want a cut off at the PI frequency

(fs/2), Wc=1, with a very high order, then the filter returned seems to be

in error. Example of failure :


[b,a] = butter(12, 0.99);

[b,a] = butter(128, 0.95);


I assume i have passed the limits of the Octave capability.


Currently using Fedora 26, Octave v4.2.1.


I had a quick look at sourceforge - nothing about limits of the order or the

cut off frequency. 


Any guidance gratefully received. 


Regards,

Shadders. 




--

Sent from: http://octave.1599824.n4.nabble.com/Octave-General-f1599825.html


_______________________________________________



"Example of failure"- what are the exact error messages ?

--Sergei