MATLAB: How to count points outside the bound in scatter plot

calculation sampleMATLABplot

Dear all, I would like to count the points outside the bands as shown
in blue line which is 10% band in both side. The code is like this
ndata = length(data);
X = linspace(0, 1, ndata);%ndata is number of point
x = data/max(data); % data is normalized to 1 
y = dy/max(dy);
xL = linspace(0.1,1, ndata); xL = xL(:); % lower line of band

yL = linspace(0,0.9, ndata); yL = yL(:);
xU = linspace(0,0.9, ndata); xU = xU(:);
yU = linspace(0.1,1, ndata); yU = yU(:);
hold on
plot(x, y, '.k')
plot(X, X, '-k'); X = X(:); % 45 degree angled line
plot(xL, yL, '-B'); % lower line of band
plot(xU, yU, '-B'); % upperline of band
pnts = [x y];
d1 = sqrt((x-X).^2+(y-X).^2); % calculation of distance between points
idout = find(d1>0.10); % here is the 10% band width and finding distance greater than 0.1
xOut  = x(idout);
yOut  = y(idout);
plot(xOut, yOut, '.r'); Want to display points outside the band in red
hold off
However I got something like this
</matlabcentral/answers/uploaded_files/18174/After.png> this is not the correct one. I think there is some algorithm problem or problem in handling code. Could any one help me in this regard. In fact, I just want the number of points oun side the band rather than plot. Plot is just the confirming.
Thanks in advance.

Best Answer

I'm not exactly sure what's going on here (the link to your file does not work). However, if you want all data outside the lower/upper lines to be marked, you don't need some square root.
upperlim=y>x+0.1;
lowerlim=y<x-0.1;
plot(x(upperlim),y(upperlim),'ro')
plot(x(lowerlim),y(lowerlim),'co')
fprintf(1,'Data below limits: %d; data above limits: %d',sum(lowerlim),sum(upperlim))
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