design of direct form IIR Filter

[kalyan]

while designing IIR filters(dirtect form coeff) using advanced IIR filtering VIs, i hv found that for a given filter spec,the coeff generated by LV and matlab are different in some cases specially higher order filters. The direct coeff. of a 6th order butterworth bandstop filter, fL=65 Hz and fH= 222Hz, when used in matlab showed a considerably different respose than LV, and the step response when evaluated in matlab turned out to be unstable. can someone explain the discrepancy. Thanks.

[Evan]

It sounds like they are just using different algorithms. I would suggest e-mailing into the NI support, with the Matlab script and the LabVIEW VI you are using. They may be able to find out where or how the two algorithms differ.