# here the program for rr interval, pls any one check any say correct or wrong. if it wrong, correctio

Discussion in 'MATLAB' started by nethaji anandhavalli, Apr 17, 2010.

1. ### nethaji anandhavalliGuest

clc;
clear;
y= load ('C:\Program Files\MATLAB71\work\ecg2.txt'); %load the original signal
t=load('C:\Program Files\MATLAB71\work\final1.txt');
WidthPoints=length(y)/40;
disp (WidthPoints)% Change to match approx. # of points in your peaks
SlopeThreshold=WidthPoints^-2;
disp (SlopeThreshold)% Change to match approx. # of points in your peaks
AmpThreshold=min(y)+0.05*(max(y)-min(y));
smoothwidth=round(WidthPoints/2); % SmoothWidth should be roughly equal to 1/2 the peak width (in points)
FitWidth=round(WidthPoints/2); % FitWidth should be roughly equal to 1/2 the peak widths(in points)
if FitWidth<3,FitWidth=3;end
PeakNumber=0;
smoothwidth=round(smoothwidth);
FitWidth=round(FitWidth);
d=fastsmooth(deriv(y),smoothwidth);
n=round(FitWidth/2+1);
P=[0 0 0 0];
vectorlength=length(y);
pe=1;
AmpTest=AmpThreshold;
for j=smoothwidth:length(y)-smoothwidth,
if sign(d(j)) > sign (d(j+1)), % Detects zero-crossing
if d(j)-d(j+1) > SlopeThreshold*y(j), % if slope of derivative is larger than SlopeThreshold
if y(j) > AmpTest, % if height of peak is larger than AmpThreshold
for k=1:FitWidth, % Create sub-group of points near peak
groupindex=j+k-n+1;
if groupindex<1, groupindex=1;end
if groupindex>vectorlength, groupindex=vectorlength;end
xx(k)=y(groupindex);yy(k)=t(groupindex);
end
[coef,S,MU]=polyfit(xx,log(abs(yy)),2); % Fit parabola to log10 of sub-group with centering and scaling
c1=coef(3);c2=coef(2);c3=coef(1);
PeakX=-((MU(2).*c2/(2*c3))-MU(1)); % Compute peak position and height of fitted parabola
PeakY=exp(c1-c3*(c2/(2*c3))^2);
MeasuredWidth=norm(MU(2).*2.35703/(sqrt(2)*sqrt(-1*c3)));

% if the peak is too narrow for least-squares technique to work
% well, just use the max value of y in the sub-group of points near peak.
if FitWidth<7,
PeakY=max(yy);
pindex=val2ind(yy,PeakY);
PeakX=xx(pindex(1));
end

% Construct matrix P. One row for each peak
% detected, containing the peak number, peak
% position (x-value) and peak height (y-value).
P(pe, = [round(pe) PeakX PeakY MeasuredWidth];
pe=pe+1;
end
end
end
end
val=200;
[index,closestval]=val2ind(y,200)
% Returns the index and the value of the element of vector x that is closest to val
% If more than one element is equally close, returns vectors of indicies and values
% Tom O'Haver () October 2006
% Examples: If x=[1 2 4 3 5 9 6 4 5 3 1], then val2ind(x,6)=7 and val2ind(x,5.1)=[5 9]
% [indices values]=val2ind(x,3.3) returns indices = [4 10] and values = [3 3]
dif=abs(y-val);
index=find((dif-min(dif))==0);
closestval=y(index);

nethaji anandhavalli, Apr 17, 2010

2. ### Mark ShoreGuest

Why on Earth would anyone want to try to debug Tom O'Haver's code for you, assuming that it even *needs* debugging? This is presumptuous behaviour - at best - on your part (and I'm being generous).

Mark Shore, Apr 17, 2010

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