load x.mat
load y.mat
slope1 = gradient(y);
slope2 = diff(y) ./ diff(x);
slope3 = gradient(y, x); % Consider x in the slope
plot(x, y, 'k-'); hold on;
plot(x, slope1, 'r-');
plot(x(2:end), slope2, 'b-');
plot(x, slope3, 'bo');
This shows, that diff(y)./diff(x) is a bestter choice except for the missing element, because diff(x) has one element less than x.
