There may be a better way to import the text file so the data is automatically read in as numeric values. Try using the Import Data button on the Home menu and see if you can change the settings for the data to be read in how you would like.
Post a couple lines of text file and I may be able to identify the best way to read it in.
If that doesn't work this is a way to reformat the data.
You could use regexp to split the string or the function strsplit. This will give you a cell array of the values you can then to convert to a numeric array after removing and empty values.
% split the string
sepVals = regexp(data{3, 1}, ' ', 'split');
% remove empties
sepVals = sepVals(~cellfun(@isempty, sepVals ));
% convert to numbers
numbers = str2double(sepVals);
You can then use xlswrite to write the array numbers to an excel sheet.
