Loop Rate of Change with Negative Values

Hello,

I would like to use a loop to calculate across a table a rate of change ( (Current Value - 4thValue) / 4th Value)).

I tried using "prcroc" but i doesnt work on negative values. Please see time series attached.

Thanks!

Answer 1

[Mathieu NOE]

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)

[IDN]

Thanks!