Ciuban - you somehow need to use your j when updating B so that you don't overwrite previously stored data with the data from the current iteration. You could try creating a cell array of the structures as
[~,m]=size(obs);
% create an array for the structs
allData = cell(1,m);
for j=1:m;
[~,n]=size(obs(j).data);
% size B appropriately
B = repmat(struct('data',[]),1,n);
for i=1:n
A=extr(eph,obs(j).data(1,i));
B(i).data=A;
end
% assign B to allData
allData{j} = B;
end
At each iteration, the code "resets" B given the number of columns in the jth observation data vector. At the end of the inner for loop, we just assign B to the jth element of the allData cell array. Once completed, allData is a 1x2880 cell array of structures.
