Scilab Function
Last update : 3/11/2005

butter - BUTTERWORTH FILTER DESIGN IN Z-DOMAIN

Calling Sequence

[B,A] = butter(n,filtertype,filterfreq)

Parameters

Description

This function calculates the filter coefficients for a butterworth filter in the z-domain, so that the output value of the filter is given by:

a(1)*y(n) = b(1)*x(n) + b(2)*x(n-1) + ... + b(nb+1)*x(n-nb) - a(2)*y(n-1) - ... - a(na+1)*y(n-na)

This function emulates the MatLab Butter function from the signal toolbox. For the realization the SciLab-functions "iir", "coeff", "denom" and "numer" are used. If the filtertype is 'bp' or 'sb', then you need a vector for the argument filterfreq.

Examples

[B,A]=butter(8,'lp');
x=rand(1,300,'normal');
y=mtlb_filter(B,A,x);
t=0:1:299;
plot2d(t,x,style=3);
plot2d(t,y,style=2);
// end of example butter 

See Also

mtlb_filter ,  

Authors

Dr. Andreas Geissler geisslea@web.de