ecg=load('ps2ex_ecg2.txt')';

sampling=300;
ww=-pi:1/sampling:pi;
w2=35/(sampling/2);
[bi,ai]=butter(2,w2,'low');
z=freqz(bi,ai,ww);
subplot(5,1,1)
plot(ww,abs(z))
fecg=filter(bi,ai,ecg)

[bn,an]=notch(10,60,sampling)
ffecg=filter(bi,ai,fecg)
zn=freqz(bn,an,ww);
subplot(5,1,2)
plot(ww,abs(zn))

subplot(5,1,3)
plot(ecg)
subplot(5,1,4)
plot(fecg)
subplot(5,1,5)
plot(ffecg)