Nice job but I believe there is a small problem.
xlwrite is able to create an xlsx file with multiple worksheets which I can open with Excel but I cannot read this file with xlsread. However, if I open the xlsx file with excel and then simply hit save (ostensibly making no changes), I can then open with xlsread.
A great submission but there seems to be problems when I use xlsread to read these files. I am unable to read an xlsx workbook with multiple worksheets created with xlwrite (on a Mac). I just get "Worksheet not found".