I have a ecg signal, want to plot the signal between the range 20-30 samples. How can I plot? below is my given code of the given signal

D = load('16265m.mat');
  x1 = D.val;
  t = linspace(0,60, size(x1,2));
  subplot(2,1,1)
  plot(t,x1)
  axis tight
  xlabel('Samples')
  ylabel('Amplitudes')
  title('Raw ECG signal')
  [z, a]=butter(5,0.5,'low');
  x=filter(z,a,x1);
  N = length(x1);
  t = linspace(0,60, size(x,2))
  subplot(2,1,2)
  plot(t,x)
  axis tight
  xlabel('Samples')
  ylabel('Amplitudes')
  title('Filtered ECG signal')

[Star Strider]

What do you mean by ‘between the range 20-30 samples’ ?

Note that you need to define your sampling frequency in order to correctly calculate your time vector, using the sampling interval. (It is provided for the PhysioBank data for each record.)