1. The error, "Unrecognized function or variable 'Newfolder'." means that the variable 'Newfolder' is not defined in the function that's calling xlsread, at the time xlsread is called.
2. The square brackets construct a file name by horizontally concatenating the variables 'Newfolder' and 'Mono70W999'. Example:
Newfolder = 'C:\Data';
Mono70W999 = 'Project1.xlsx';
result = [Newfolder, Mono70W999]
Then that file name is passed to xlsread as the only input, so this is using the "num = xlsread(filename)" syntax.
Note that fullfile is better than square brackets for constructing file paths because it inserts directory separators between its arguments as needed. Example:
result = fullfile(Newfolder, Mono70W999)
[MATLAB Answers runs on a Linux platform,which uses slash ( / ) so that's why that's there. If you run it in Windows you'd get a backslash ( \ ) instead.]
3. The purpose of ~ is to indicate that the second output from xlsread is discarded. In this case, the ~ is unnecessary because the first output of xlsread is the same regardless of how many outputs are requested, so you'd get the same behavior with out = xlsread(filename) syntax.
Some other function besides xlsread might output different things depending on how many outputs are requested, in which case the [out1,~] = func(in) syntax might be necessary.
