Question

I have the following data: ET = [1 3 5 7 6 4], and below is my code:

for i=1:3
    meanET(i)=ET(:,1+(2*i-2)); %//for i=1,extract ET column 1 data
    stdET(i)=ET(:,2+(2*i-2)); 
    totalET(i)=meanET(i)+stdET(i)
end

However, MATLAB display’s an error that says that in the assignment A(I)=B, the number of elements in B and I must be the same, and therefore I modified my code to this:

for i=1:3
    meanET=ET(:,1+(2*i-2));%for i=1,extract ET column 1 data
    stdET=ET(:,2+(2*i-2)); 
    totalET=meanET+stdET
end

After running the latter code, it showed meanET=6, stdET=4, and totalET=10, which means that it only stored the data for i=3 in the workspace. I want to get the result like
totalET=[4 12 10] in the workspace, corresponding to i = 1, 2, 3. How do I do that?

Answer 1

you should just declare your target array at the beginning of your code:

meanET=zeros(size(ET,1),3);
stdET=zeros(size(ET,1),3);
for i=1:3
   meanET(:,i)=ET(:,1+(2*i-2));
   stdET(:,i)=ET(:,2+(2*i-2)); 
end
totalET=meanET+stdET