Percentage change in the Y axix for unit change in X axis

If I have a 2D plot, how can I calculate the percentage change in the Y axix for unit change in X axis?

Answer 1

[Jonas]

if you have y data along x you can calculate diff(y)./diff(x) to get the derivate. to get the pointswise percentage value divide additionally by y(1:end-1). FInally mutiply by 100 to get percentage values

x=201:300; y=1:100;
plot(x(2:end),diff(y)./diff(x)./y(1:end-1)*100);
ylabel('change in %')