Re: Why is my Butterworth filter so noisy?

[Matthias Brennwald]

On 22.09.2008, at 18:12, Sergei Steshenko wrote:

> You might be interested in the following:
>
> http://www.nabble.com/ripple-in-Butterworth-filter-created- 
> by-'butter'-(was-"RE%3A-'long-double'-support--")- 
> td17092962.html#a17092962

Ok. So THE recommended way of using butter.m is to not return the  
filter coefficients, but the have it return the poles, zeros, and the  
gain. So I'd to the following:

[z,p,g] = butter (...)

Now, how should I use z, p and g to filter my data? I believe I  
cannot use filter.m with these data.

Matthias