trying to calculate the central diff approximation
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i tried multiple ways but none of them worked. kind of stuck and not sure what to do. what i'm trying to do is find current value that is equal to one ahead minus one below all divided by .2
Phase_1 = DATA(DATA(:,4)==1,:);
Vroll_avg1_1 = movsum((1/5).*Phase_1(:,3),[2 2]);
Vdi_1 = movsum(1/5.*Vroll_avg1_1,[2 2]);
---> first try: Adi_1 = [Vdi_1(2:Vdi_1+1,:)-Vdi_1(1:Vdi_1-1,:)/(2*T)];
---> second try: Adi_1 = ((Vdi_1(2:end+1) - Vdi_1(1:end-1))/(2*T)); % error says index exceeds array bounds. i understand why but how((2:end+1)) would i get it to work?
---> third try: %K = length(Vdi_1);
%Q = length(Vti_1);
%for M = 2:(length(Vdi_1)-1)
% Adi_1 = ((Vdi_1 - Vdi_1)./(2.*T));
%Adi_1 = (Vdi_1(2) - Vdi_1(1))./(2.*T);
%Adi_1(length(Vdi_1)) = (Vdi_1(K) - Vdi_1(K))./(2.*T);
really need help, please try to help me figure this out.