To filter a matrix with a butterworth filter

Hi!

I've already ask a similar thing but i had some problems, probably i didn't understand or explained myself very well.

I need to filter a matrix (divided in columns) with a passband butterworth filter, 4th order with frequencies 0.1hz and 25hz. My sampling rate is 200 per second. Please type the entire code

thanks for the help Federico

Answer 1

[Jan]

Have you read the documentation of BUTTER? There you find all you need. Consider that the replied filter has the order 2*N and that Wn is normalized by the Nyquist frequency, which is the half frequency.

Just try it and post your approach here. Then the doit4me, no attempt, typeit4me tags will loose their power.

[federico valenti]

Jan i did it time ago, i wish to know if i did it right because i got strange results -_-

here my code

order=2;

f1=0.1;

f2=25;

rate=200;

[B,A] = butter(order,[f1/(rate/2) f2/(rate/2)]);

filteredMatrix=filter(B,A,matrixToFilter);

what do you think about?

thx

[Jan]

Exactly. Because the filter parameters are correct, the problem must be somewhere else.

[federico valenti]

always nice Jan thank you!