Benjamin - if all files are in the same directory, you could do
filenames = {'Oxygen_1keV_300K','Oxygen_1keV_300K','Oxygen_1keV_600K','Oxygen_1keV_900K'};
data = cell(1,length(filenames));
YMean = zeros(1, length(filenames));
for k=1:length(filenames)
sFilename = [fullfile('C:\Users\Ben\Desktop\', filenames{k}) '.xlsx']
data{k} = xlsread(sFilename,...);
% do your calculations on data{k}
% calculate and save the mean
YMean(k) = ...;
end
Note how we create a cell array of filenames by using the curly braces {} rather than concatenating the strings together using the square brackets []. We then iterate over each element in the filenames array and create a full filename, sFilename, which has a path to the file with the xlsx extension.
