How to separate a signal into 4 second segments?

Lets say I have an ECG signal and I want to separate it 4 second segments. How to do it in MATLAB?

 % MATLAB Code
load ('C:\Users\Explorer\Documents\MATLAB\PhysioNet_Database\Malignant_Ventricular_Ectopy_Database\418m.mat');
signal=val(1,:);
plot(signal)
xlabel('Time')
ylabel('Voltage')

Answer 1

[Walter Roberson]

If you have the signal processing toolbox, see buffer(), provided the signals are equally spaced in time.

[Explorer]

How to check whether ECG signal that I have attached is equally spaced in time or not?

[Star Strider]

The Physionet EKGs are all sampled at constant time intervals, but the intervals are different in different records. The sampling frequencies and other data for each record are all available in the database.

[Explorer]

Thank you guys!