hello
you need to "realign" your two data sets vs common x vector - in other words we need to creat a new x vector and interpolate both y datas vs this new x vector - here I opted for pchip interpolation method.
the bottom plot is your delta vector , I picked only a few values to be displayed on the top plot
hope it helps !!
load coords_mine.mat
load coords_sir.mat
% take unique only x data
[a,ia,ic] = unique(a);
b = b(ia);
[x2,ia,ic] = unique(x2);
y2 = y2(ia);
% plot
figure(1);
subplot(211),
plot(a,b ,'.g') % code 1
hold on
plot(x2,y2,'.b') % code 2
% create common x axis data
xmin = max(a(1),x2(1));
xmax = min(a(end),x2(end));
xnew = linspace(xmin,xmax,300)';
% and interpolate y data using pchip method
bnew = interp1(a,b,xnew,'pchip');
y2new = interp1(x2,y2,xnew,'pchip');
delta = abs((bnew - y2new)./y2new) * 100;
xCenter = 1:30:length(bnew); % NB decimation factor 30 vs 300 original data points => 10 values displayed
yCenter = (bnew+y2new)/2;
yCenter = yCenter(xCenter);
for k = 1 : numel(xCenter)
textLabel = sprintf('%.3f', delta(xCenter(k)));
text(xnew(xCenter(k)), yCenter(k)*1.1, textLabel, 'HorizontalAlignment', 'center')
end
plot(xnew(xCenter),yCenter,'xk','markersize',15)
subplot(212),
plot(xnew,delta,'b') %
