hello
I assumed that the time axis in your file is as folows : first (top value) is the oldest and last (bottom) is the newest
clc
clearvars
data = xlsread('VBC.xlsx');
% time axis supposed : first (top value) is the oldest and last (bottom) is the newest
% rate of change = (data(index) - data(index - 4))/data(index - 4)
RoC(1:4) = 0;
for ck = 5:numel(data)
RoC(ck) = (data(ck) - data(ck - 4))/data(ck - 4);
end
plot(RoC)
