Matlab code to plot the power density spectrum for the time intervals obtained from R-R interval-

Code tused until now to find R-R interval is as follows:

clc;

load('ecg234m.mat'); %%%%%load the data into matlab

plotATM('ecg234m');

base= 1024;

gain= 200;

fs = 1000; % Sampling rate

val= (val-base)/gain; %generate a val matrix similar to the part 1 of this project

val=val(1:217000); % trmming for first 10minutesof the signal

interval=0.002777;

x=(1:size(val, 2)) * interval;

plot(x,val); % plotting the unfiltered data

xlabel('time(s)');

ylabel('amplitude');

title('ECG FOR RECORD 234');

figure;

value=(val(1:217000));

y=0.25*max(value);

[pks,locs]=findpeaks(value,'minpeakheight',y,'minpeakdistance',100);

plot(x,value,x(locs),pks,'Or')

title('QRS peaks');

QRSPEAK=x(locs); %%%%% finding for R-R interval, find the peak time

RRinterval=diff(QRSPEAK); % take the difference of consecutive peaks

avg=mean(RRinterval);

disp(avg);

plot(QRSPEAK(2:end),RRinterval)

title('R-R Interval of the Arrhythmic signal')

xlabel('time(s)')

ylabel('Duration of R-R interval ')

figure

Please explain the steps.