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Can any1 please explain me what does X= 0.01 : 0.01 : 2; and li=30/72 meant in ECG signal generation using Fourier series work done by R.KARTHIK sir. Iam new in MATLAB.Its very urgent.

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Meha Gadkari
Meha Gadkari on 16 Sep 2016
Commented: Meha Gadkari on 19 Sep 2016
x=0.01:0.01:2;
default=input('Press 1 if u want default ecg signal else press 2:\n');
if(default==1)
li=30/72;
a_pwav=0.25;
d_pwav=0.09;
t_pwav=0.16;
a_qwav=0.025;
d_qwav=0.066;
t_qwav=0.166;
a_qrswav=1.6;
d_qrswav=0.11;
a_swav=0.25;
d_swav=0.066;
t_swav=0.09;
a_twav=0.35;
d_twav=0.142;
t_twav=0.2;
a_uwav=0.035;
d_uwav=0.0476;
t_uwav=0.433;
else
rate=input('\n\nenter the heart beat rate :');
li=30/rate;
%p wave specifications
fprintf('\n\np wave specifications\n');
d=input('Enter 1 for default specification else press 2: \n');
if(d==1)
a_pwav=0.25;
d_pwav=0.09;
t_pwav=0.16;
else
a_pwav=input('amplitude = ');
d_pwav=input('duration = ');
t_pwav=input('p-r interval = ');
d=0;
end
%q wave specifications
fprintf('\n\nq wave specifications\n');
d=input('Enter 1 for default specification else press 2: \n');
if(d==1)
a_qwav=0.025;
d_qwav=0.066;
t_qwav=0.166;
else
a_qwav=input('amplitude = ');
d_qwav=input('duration = ');
t_qwav=0.166;
d=0;
end
%qrs wave specifications
fprintf('\n\nqrs wave specifications\n');
d=input('Enter 1 for default specification else press 2: \n');
if(d==1)
a_qrswav=1.6;
d_qrswav=0.11;
else
a_qrswav=input('amplitude = ');
d_qrswav=input('duration = ');
d=0;
end
%s wave specifications
fprintf('\n\ns wave specifications\n');
d=input('Enter 1 for default specification else press 2: \n');
if(d==1)
a_swav=0.25;
d_swav=0.066;
t_swav=0.09;
else
a_swav=input('amplitude = ');
d_swav=input('duration = ');
t_swav=0.09;
d=0;
end
%t wave specifications
fprintf('\n\nt wave specifications\n');
d=input('Enter 1 for default specification else press 2: \n');
if(d==1)
a_twav=0.35;
d_twav=0.142;
t_twav=0.2;
else
a_twav=input('amplitude = ');
d_twav=input('duration = ');
t_twav=input('s-t interval = ');
d=0;
end
%u wave specifications
fprintf('\n\nu wave specifications\n');
d=input('Enter 1 for default specification else press 2: \n');
if(d==1)
a_uwav=0.035;
d_uwav=0.0476;
t_uwav=0.433;
else
a_uwav=input('amplitude = ');
d_uwav=input('duration = ');
t_uwav=0.433;
d=0;
end
end
pwav=p_wav(x,a_pwav,d_pwav,t_pwav,li);
%qwav output
qwav=q_wav(x,a_qwav,d_qwav,t_qwav,li);
%qrswav output
qrswav=qrs_wav(x,a_qrswav,d_qrswav,li);
%swav output
swav=s_wav(x,a_swav,d_swav,t_swav,li);
%twav output
twav=t_wav(x,a_twav,d_twav,t_twav,li);
%uwav output
uwav=u_wav(x,a_uwav,d_uwav,t_uwav,li);
%ecg output
ecg=pwav+qrswav+twav+swav+qwav+uwav;
figure(1)
plot(x,ecg);

Answers (1)

Luuk van Oosten
Luuk van Oosten on 16 Sep 2016
X= 0.01:0.01:2;
means X-values vary from 0.01 to 2 with a step size of 0.01. So you end up with X being 200 values equally spaced (with 0.01) in the range 0.01 and 2. My best guess is that this is your time window (or whatever values you have on your X-axis for your ECG).
li=30/72
means that the value specified as 'li' has the value of 30/72, commonly known as 0.4172. The 72 refers here to heartbeat (in rest, I guess). If your heartbeat goes up, li goes down and vice versa.

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Meha Gadkari
Meha Gadkari on 16 Sep 2016
Thank you so much sir. From your answer i can conclude that "li" is the heart beat rate which could have any value. Now i only want to know what does "30" stands for? what is its significance?
Walter Roberson
Walter Roberson on 16 Sep 2016
You need to read the documentation that was provided as part of that File Exchange Submission as unfortunately there is no useful comments in the source.

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