i have a problem in this code of band passing a EEG SIGNAL 8-30 hz ? can you find the error ? give a solution to this ? i have used butterworth filter ? is it a IIR FILTER OR FIR FILTER ? in the below code sampling freq =250 ,x is dataset.

x=train_data('1,:,1'); Fs=250; Ts=1/Fs; % z_1=m*Ts; % z_2=ceil(m*Ts); t=0:Ts:3.999; t=t'; Fn=Fs/2; % Stopband Frequency (Normalised) Wp = [8 30]/Fn; Ws = [7.8 31]/Fn; Rp = 3; Rs = 40; [n,Wn] = buttord(Wp,Ws,Rp,Rs); [z,p,k] = butter(n,Wn); sos = zp2sos(z,p,k); filtered_signal = filtfilt(sos,x); figure,plot(t,filtered_signal);%